2019 Fall Meeting
ENERGY AND ENVIRONMENTM
Metal oxide- and oxyhydride-based nanomaterials for energy and environment-related applications
Metal oxide and oxyhydride nanomaterials possess many technologically important properties that can be tuned by controlling the shape and size. The aim of the symposium is to bring academic scientists, engineers, and industry to exchange their results about latest developments on the topic.
Nowadays, nanomaterials are becoming commercialized. Current theoretical and experimental studies aim to further increase the impact that the nanomaterials can play in technological advances. In recent years, new materials and devices based on transition metal oxide and oxyhydride nanomaterials, and their hybrids with organic compounds have been developed that present interest for applications in energy storage, energy harvesting, energy saving, energy conversion, and environmental technologies. Furthermore, the recent years have seen the development and improvement in synthesis and characterization techniques, computational tools and software for simulation, data analysis and fitting. This Symposium will provide an overview of the state of the art and most recent scientific and technical progress as well as market situation, identification of key areas, challenges, approaches, and technologies in this field. The symposium is multidisciplinary. It covers new advances in metal oxide and oxyhydride nanomaterials development, 2D materials, theoretical and experimental methods of synthesis and characterization. Transition metal oxides such as, e.g., Ga2O3, SnO2, GeO2, TiO2, SiO2, Bi2O3 etc., rare earth metal oxides such as, e.g., CeO2, Gd2O3, Dy2O3, etc., transition metal oxyhydrides such as e.g., LaHO, ABO3-xHx, YHO, GdHO, DyHO, etc will be under the focus of the Symposium along with the life cycle assessment, eco-toxicological assessment, risk assessment, influence of the particles on human health, applications in environmental technologies, energy production, energy storage, and energy saving.
Hot topics to be covered by the symposium:
- Metal oxide-based nanomaterials
- Transition metal oxyhydrides
- 2D materials
- Defects and impurities, functional properties and new phenomena
- Theoretical and experimental methods of research
- Applications of the nanomaterials in:
a) energy conversion devices
b) energy storage devices (batteries and super-capacitors),
c) power electronics
d) environmental applications (sensors, waste water treatment, air cleaning, photocatalytic processes)
e) superhydrophobic, anti-ice, anti-dust coatings
f) medicine and biotechnology
- Life-cycle assessment
- Risk assessment
List of invited speakers:
- Kageyama, Hiroshi, Kyoto Univ, Grad Sch Engn, Nishikyo Ku, Kyoto 6158581, Japan.
- David Rogers, Nanovation SARL, France.
- Sanjay Mathur, Institute of Inorganic Chemistry University of Cologne, Germany.
- Su Huai Wei, Beijing Computational Science Research Center, China.
- Max Wolff, University of Uppsala, Uppsala, Sweden.
- Giancarlo Salviati, Institute of Materials for Electronics and Magnetism IMEM, Parma, Italy.
- A. Subrahmanyam, Indian Institute of Technology Madras, Chennai, India.
- Aleksandra Djurisic. University of Hong Kong, Hong Kong.
- Marco Altomare, Friedrich-Alexander Universität Erlangen-Nüremberg, Germany.
- S. Balakumar, University of Madras, Chennai, India.
- Neslihan Yuca, ENWAIR AS, Istanbul, Turkey.
- Martin Eickhoff, Institute of Solid State Physics - Semiconductor Epitaxy - University of Bremen, Germany.
- Martin Albrecht, Leibniz-Institut für Kristallzüchtung, Berlin, Germany.
- Joana Rodrigues, Departamento de Física & I3N/FSCOSD, Universidade de Aveiro, Aveiro, Portugal.
- Andrej Kuznetsov, Center for Materials Science and Nanotechnology (SMN), University of Oslo, Norway.
Scientific committee members:
- Malle Krunks, Tallinn University of Technology, Tallinn, Estonia.
- Luminita Andronic, Transilvania University of Brasov, Brasov, Romania.
- Darius Milcius, Lithuanian Energy Institute, Kaunas, Lithuania.
- Jose Montero, University of Uppsala, Uppsala, Sweden.
- Esra Ozkan Zayim, Istanbul Technical University, Istanbul, Turkey.
- Vishnukanthan Venkatachalapathy, University of Oslo, Oslo, Norway.
- Larysa Khomenkova, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences, Ukraine
- Jan Grym, Institute of Photonics and Electronics, Czech Academy of Science, Czech Rep.
- Eugen Stamate, Technical University of Denmark, Roskilde, Denmark.
Selected papers will be published in two journals “Materials Letters” (Elsevier) https://ees.elsevier.com/mlblue/default.asp in the special issue “VSI:Environmental materials and open access MDPI journal “Molecules” https://www.mdpi.com/journal/molecules/special_issues/materials_solar
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|08:50||Session I. Oxyhydride and oxide nanomaterials and applications. Chairs: Malle Krunks and Smagul Karazhanov|
Authors : Hiroshi Kageyama
Affiliations : Kyoto University
Resume : The introduction of hydride (H?) into an oxide leads to interesting properties. Of particular importance is the labile nature of the hydride anion , making BaTi(O,H)3 perovskite a suitable precursor for anion-exchange reactions to access novel mixed-anion compounds that include oxynitride and oxide-nitride-hydroxide [3, 4]. An important topic in solid state ionics is to explore oxyhydrides with hydride conductivity toward the realization of all-solid-state hydride-based batteries . The hydride ability of lattice diffusion at moderate temperatures can be exploited to catalysis. We recently demonstrated a titanate oxyhydride that can catalyze ammonia synthesis without Ru or Fe metal. This is unprecedented because titanium is regarded as an inert element due to the fairly strong Ti?N bonding , suggesting that the introduction of H? to the titanium oxide can break the scaling rules. We suggest that a rare hydrogen-based Mars van Krevelen mechanism may be at play here. When Ru, Fe, and Co particles are supported onto BaTiO2.5H0.5, we observed enhanced activities and altered kinetic parameters, with the details depending on the choice of supported metals (Ru, Fe, Co) . Overall, the high activity is due to a hydrogen-based Mars?van Krevelen mechanism decreasing the hydrogen poisoning, and also as hydride functioning either as a strong electron donor. Which of these effects visibly dominates depends on the metal supported. If time allows recent results on oxyhydrides with the fluorite structure will be briefly shown [8, 9]. References  H. Kageyama et al., Nat. Commun. 2018, 9, 772.  Y. Kobayashi et al., Nat. Mater. 2012, 11, 507.  N. Masuda et al., J. Am. Chem. Soc., 2015, 137, 15315. JACS Spotlighted.  T. Yajima et al., Nat. Chem., 2015, 7, 1017.  G. Kobayashi et al., Science 2016, 351, 1314.  Y. Kobayashi J. Am. Chem. Soc. 2017, 139, 18240.  Y. Tang et al., Adv. Energ. Mater. 2018, 1801772. Highlighted in Nat. Catal.  H. Yamashita et al., J. Am. Chem. Soc. 2018, 140, 11170.  T. Broux et al., J. Am. Chem. Soc., in press.
Authors : Eric V. Sandana, David J. Rogers, Philippe Bove, Ferechteh H. Teherani
Affiliations : Nanovation, 8 route de Chevreuse, 78118 Chateaufort, France
Resume : Zinc oxide (ZnO) is a remarkable, multifunctional semiconducting material with a direct, wide bandgap (Eg ~ 3.4 eV), intrinsically high transparency over the whole visible range, and a resistivity that can be tuned from semi-insulating right through to semi-metallic by doping. It also presents one of the highest piezoelectric responses of any semiconductor and has a relatively high thermoelectric figure of merit. Moreover, it has been judged to be biocompatible and has been approved for human consumption (in products such as vitamin pills) by the U.S. Food and Drug Administration. Over the past decade ZnO has become a hot topic because of its? distinctive property set plus a number of recent breakthroughs which predispose it for use in a whole range of energy harvesting applications from solar cells, through nanowire piezogenerators to thermoelectrics. In this talk, we will give an overview of these advances and present some of the wide range of ZnO-related devices and applications being researched at the moment with illustrations from the work of the French ZnO start-up, Nanovation (www.nanovation.com).
Authors : L. Andronic 1, D. Moldarev 2,3, E. M. Baba 2,4, E. Moons 5, D. Deribew 5, S. Zh. Karazhanov 2
Affiliations : 1 Department of Product Design, Mechatronics and Environment, Transilvania University of Brasov, Brasov, Romania 2 Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway 3 Department of Materials Science, National Research Nuclear University, 115409 Moscow, Russia 4 Nanoscience & Nano Engineering Department, Istanbul Technical University, 34469 Istanbul, Turkey 5 Department of Engineering and Physics, Karlstad University, SE-65188 Karlstad, Sweden
Resume : Oxyhydrides of yttrium (YHO) and gadolinium (GdHO) belong to an emerging class of materials with oxide and hydride anions sharing the same sites in the lattice. Here we report the results of synthesis, characterization and a photocatalytic activity study of the materials for waste water treatment. By optical measurements we show that at the moment when the materials are illuminated by sunlight, they are transparent to visible light with a transparency exceeding 85% and can absorb about 10% of sunlight. However, the light absorbing properties of the materials will be increased with exposure time and in the photodarkened state, they can absorb about 40% of sunlight. Kelvin probe measurements show work function values between 2.9 and 4.2 eV for YHO and between 3.4 and 4.2 eV for GdHO depending on the H2/Ar pressure in the deposition chamber. Photocatalytic efficiency of the YHO and GdHO powders exceed 75%. However, thin films of the materials show less photocatalytic properties, because of the lower surface-to-volume ratio of thin films compared to powders. We will present also the results of a study of structural and porosity measurements.
Authors : T. ??cki 1, K. Zar?bska 1-2, M. Skompska 1-2
Affiliations : 1 Laboratory of Electrochemistry, Faculty of Chemistry, University of Warsaw, Warsaw, Poland; 2 Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, Warsaw, Poland.
Resume : The purpose of this work was to obtain a photocatalytic system based on inorganic perovskite modified by various materials or dopants to improve separation of photogenerated electron-hole pairs or obtain the system which is active under visible light. The TiO2/SrTiO3 composite reveals cascade structure. A combination of SrTiO3 with graphene quantum dots (QD) or graphitic carbon nitrate (g-C3N4) modifies the mechanism of photocatalytic process from cascade to scheme-Z. Another way of modification of SrTiO3 was doping with metal ions. Addition of Co2+, Fe3+, La2+ during synthesis facilitate obtaining photocatalytic system active under visible light. It is expected that dopant ions replace Sr2+ or Ti4+ in the lattice or generate the structural defects which on the other hand may act as the charge traps. The first step of preparation of photocatalytic TiO2/SrTiO3 system supported on the solid substrate was deposition of TiO2 layer on FTO by hydrothermal method. In the second step the TiO2 layer was converted into SrTiO3 by dissolution-precipitation process in the presence of dopant ions. Deposition of graphene QDs or g-C3N4 on the surface of modified SrTiO3 was achieved via hydrothermal method. Photoactivity of the resultant hybrid systems was examined under visible light irradiation on model pollutants: 4-chlorophenol and methyl orange. Photocatalytic systems were also investigated by means of electrochemical methods to determine charge transfer parameters, e.g. electron lifetime.
|10:45||Session II Photocatalysis and applications. Chairs: David Rogers and Luminita Andronic|
Authors : Sanjay Mathur, Thomas Fischer
Affiliations : Chair, Inorganic and Materials Chemistry University of Cologne, Greinstrasse 6, D-50939 Cologne, Germany E-mail: firstname.lastname@example.org
Resume : Metal oxide nanostructures with hetero-contacts and phase boundaries offer unique platform for designing materials architectures for energy harvesting applications. As viable alternative to water electrolysis, photoelectrochemical (PEC) water splitting has emerged as a competitive technology being capable of converting solar energy directly into chemical energy using stable and efficient photocatalysts for solar hydrogen production. Nanostructured metal oxides and composite materials are promising candidates for effective photoanodes, which are fabricated using CVD, PE-CVD and ALD techniques for producing multilayered electrodes as oxygen evolution reaction catalysts. Besides the size and surface effects, the modulation of electronic behaviour due to junction properties leads to modified surface states that promote selective decomposition of analytes and adsorbates. The growing possibilities of engineering nanostructures in various compositions (pure, doped, composites, heterostructures) and forms has intensified the research on the integration of different functional material units in a single architecture to obtain new photocatalytic materials. In addition, new concepts of enhancing charge transduction by surface functionalization are promising strategies to promote specific chemical interactions, however the challenge related to reproducible synthesis and device integration of nanomaterials persist. This talk will present how chemically grown and designed thin films and bilayers of different metal oxides unfold new material properties, which can be transformed into advanced material technologies.
Authors : Choon Yian Haw, Wee Siong Chiu, Poi Sim Khiew
Affiliations : School of Energy and Chemical Engineering, Xiamen University Malaysia, Jalan Sunsuria, Bandar Sunsuria, 43900 Sepang, Selangor Darul Ehsan, Malaysia Email: email@example.com Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia. Email: firstname.lastname@example.org Faculty of Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Email: PoiSim.Khiew@nottingham.edu.my
Resume : Title: Morphological, Structural, and Optical- Properties Analysis of Shape-Controlled Synthesis of Metal Oxide Nanomaterials for Enhanced Photocatalytic and Environmental Remedial Applications Abstract Soaring prices for raw materials and energy, coupled with the elevating environmental awareness have urged the need to exploit better solution and strategies to counteract these global issues. In response to these concerns, the research towards the optimization of nanostructured materials with different dimensions is in particular of essential especially effort to find novel, low-cost and yet environmentally benign metal oxide nanomaterials. This framework aims to provide a state-of-the-art overview of our recent works in the easily up-scalable synthesis, characterization strategies and photocatalytic application of multidimensional (0D to 3D) nanomaterials, particularly of the selected typical metal oxide TiO2, SnO2, ZnO, and Fe2O3. It is evident that these materials offer a myriad of advantages as they provide intriguing morphologies, larger surface area as well as improved intrinsic optical and transport properties, thus make them more suitable for catalytic purposes. As a feasibility test of these materials ranging in various nanodimensions, we demonstrated a series of photocatalytic studies such as selected wavelength in hydrogen generation via water splitting and degradation of pollutant in wastewater treatment as a proof of concept. Their crystallographic properties, probing the heterogeneous structure and their size density will be discussed, thanks to both experimental and numerical approaches. The separation efficiency of these nanomaterials was also further affirmed by photoluminescence (PL) studies. We found that the electron mobility and intrinsic defects in photo(electro-)catalyst lattices play a pivotal role in the functionality as well as their photocatalytic activities of these nanomaterials under the abundant sunlight.
Authors : Ana Serrano-Lotina, Karen Cruz, Pedro Ávila, Miguel A. Bañares
Affiliations : Instituto de Catálisis y Petroleoquímica (CSIC), C/ Marie Curie 2 L10, Campus Cantoblanco, 28049 Madrid, Spain
Resume : Nitrogen oxides (NOx) are among the major atmospheric pollutants that contributes to acid rain, ozone depletion and photochemical smog. Selective catalytic reduction (SCR) with NH3 has been demonstrated to be the most effective method worldwide for the treatment of flue gases from stationary sources [ ]. However, N2O, with high greenhouse and ozone layer depletion potential [ ], can be generated as undesirable secondary product. In a recent article [ ] we studied the role of sepiolite as binder in a Mn-based catalytic system over SCR. Not only did the sepiolite allow the extrusion of the material but it also modulated the NOx adsorption capacity and the acidity of the system, leading to an increase in the catalytic activity with a good selectivity to N2. Here, we will describe the influence of a second metal (Co, Fe, Ce) over the physicochemical properties of the Mn/TiO2-sepiolite system as well as their catalytic behaviour. This work was supported by the Spanish Ministry [CTM2017-82335-R]. REFERENCES [ ] Fan, J.; Lv, M.; Luo, W.; Ran, X.; Deng, Y.; Zhang, W.-X.; Yang, J.; Exposed metal oxide active sites on mesoporous titania channels: a promising design for low-temperature selective catalytic reduction of NO with NH3, Chem. Commun., 54 (2018) 3783-3786. [ ] Intergovernmental Panel on Climate Change [IPCC], Climate Change 2014: Synthesis Report. Fifth Assessment Report, Switzerland, 2014. [ ] Serrano-Lotina, A., Monte, M., Iglesias-Juez, A., Pavón-Cadierno, P., Portela, R., Ávila, P., MnOx-support interactions in catalytic bodies for selective reduction of NO with NH3, Appl. Catal. B (in press)
Authors : Kobasa I.M. 1, Kropelnytska Yu.V. 2, Kondrachuk I.V. 1, Vorobets M.M. 1, Vorobets G.I. 3
Affiliations : 1 Chemical Analysis, Expertise and Safety of Food Products Department, Institute of Biology, Chemistry and Bioresources, Yuriy Fedkovych Chernivtsi National University, 58012 Chernivtsi, Ukraine, email@example.com, firstname.lastname@example.org, email@example.com 2 Department of Medicinal and Pharmaceutical Chemistry, Bukovinian State Medical University, 58002 Chernivtsi, Ukraine, firstname.lastname@example.org 3 Computer Systems and Networks Department, Institute of Physical-Technical and Computer Sciences, Yuriy Fedkovych Chernivtsi National University, 58012 Chernivtsi, Ukraine, email@example.com
Resume : Building of the heterostructures (HS) containing of a dye (D) deposited on the semiconductor?s surface and protected from washing-off by the polymer film that does not hinder any interphase electron exchange processes is one of promising directions in development of the advanced wide-zone photocatalytic systems. Such HS exhibit rather high activity in the photocatalytic decomposition of water and oxidation of iodide ions. It seems important to evaluate the feasibility limits of the above mentioned approach and to check its applicability to synthesis of the sensitized heterosystems to be used in other redox processes. Besides, a variety of some dyes should be tested in the context of their utilization as sensitizing agents. The P25 titania by Degussa and some symmetrical cationic dyes with polymethine chains of various length were used as components for synthesis of the light sensitive HS D/TiO2. Then the reduction and oxidation potentials were determined for each dye by cyclic voltammetry. Further, these potentials were used to calculate the HOMO and LUMO energy values. These data were used to understand the scheme of processes occurring in the heterostructures and solutions of dyes under irradiation of light with different wavelengths. It has been shown that the oxidation potential of the excited dye molecule (LUMO) is higher than that of the upper edge of TiO2 conductivity band for all the dyes involved in this investigation. That is why they all can be used as effective sensitizers for TiO2. This conclusion is confirmed additionally by determination of the photocatalytic activity values of HS in the test reaction of reduction of methylene blue.
Authors : Ryan Kisslinger, Sheng Zeng, Pawan Kumar, Karthik Shankar
Affiliations : Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
Resume : Titanium dioxide (TiO2) nanotubes (TNTs) are self-organized, vertically oriented arrays of nano-cylinders formed by electrochemical anodization of Ti foils or Ti thin films . The Shankar Lab at the University of Alberta has pioneered four major innovations that advance the synthetic possibilities and application spectrum of TNTs. The first innovation consists of using specific pulse shapes to form TNTs with periodically modulated diameters and wall-thicknesses , thus resulting in the bottom-up creation of 1D photonic crystals with narrow & tuneable stopbands. The second innovation consists of the all solid-state growth of TNTs through which the use of a liquid electrolyte is eliminated, and the nanotubes are instead grown in a solid polymer electrolyte . The third innovation consists of the use of magnetic field-induced Lorentz forces to perform electro-less anodization wherein the Ti foil that is anodized is not directly connected to an electrical contact . A fourth innovation consists of the generation of preferentially oriented single crystal-like TiO2 nanotube arrays on non-native substrates . REFERENCES 1. K. Lee et al. Chem. Rev. 114, pp 9385-9454 (2014) 2. X. Zhang et al. Angew. Chem. Int. Ed. 51, pp 12732-12735 (2012) 3. A. Mohammadpour et al. J. Mater. Chem. A 2, pp 13810-13816 (2014) 4. A. Hosseini et al. J. Mater. Sci.-Mater. El. 29, pp 16590-16597 (2018) 5. R. Kisslinger et al. Nanotechnology 30 (20), Art. No. 204003 (2019)
|13:55||Session III. Oxide nanomaterials. Chairs: Maximilian Wolff and Esra Ozkan Zayim|
Authors : J. Montero (1)*, J. Thyr (1), T. G. Welearegay (1) T. Edvinsson (1) Tatjana Dedova (2) Ilona Oja Acik (2) and L. Österlund (1)
Affiliations : (1) Department of Engineering Sciences, The Ångström Laboratory, Uppsala University,P.O. Box 534, SE-751 21 Uppsala, Sweden; (2) Department of Materials and Environmental Technology, School of Engineering, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia.
Resume : In this work, bi-catalysts, based on nanoparticle heterojuctions in-between nanostructured copper oxide (CuOx) and zinc oxide (ZnO) have been prepared on glass substrates, and their photocatalytic activities determined by measuring the photodegradation rate of orange II dye in water solution using different wavelengths. The bi-catalysts were prepared by two different approaches: (i) Deposition of copper oxide with different stoichiometry by reactive DC magnetron sputtering followed by the deposition of ZnO particles by drop coating. (ii) Synthesis of CuOx decorated ZnO nanorods by advanced gas deposition. The obtained bi-catalysts, were characterized by SEM, XRD, XPS, Raman and spectrophotometry. It was found that the bi-catalysts exhibited a higher photodegradation rate than either of its constituents, CuOx and ZnO, alone. This synergetic effect is attributed to the intrinsic electric field created at the pn-junction formed at the CuOx/ZnO interface facilitating a more effective charge separation between the electron-hole pairs formed upon interband photon absorption. In order to achieve this synergetic effect the constituent catalysts must have good physical contact and appropriate electronic band edge positions. For this purpose, the CuOx films were tailored by modification of the oxygen-to-argon gas mixing ratio of the sputtering plasma during deposition as well as by post-deposition annealing processes.
Authors : Martyshov M.N., Il?in A.S., Platonov V.B., Forsh P.A., Kashkarov P.K.
Affiliations : Lomonosov Moscow State University, Moscow, Russia; National Research Center ?Kurchatov Institute?, Moscow, Russia
Resume : Metal oxides are widely used to create gas sensors, photocatalysts, photovoltaic cells, memory elements, etc. Most metal oxides are n-type semiconductors. Recently, interest in p-type metal oxides has increased, which is associated with the possibility of creating different p-n heterostructures based on metal oxides. In this work n-type (ZnO, WO3) and p-type (Co3O4, NiO) metal oxide nanofibers were investigated. Nanofibers with diameters of 100-250 nm were obtained by electrospinning technique. To study their electrical properties, thin films of the materials were deposited on a glass substrate. Gold contacts were deposited on the top of the films. The structure of the samples was studied by X-ray diffraction, scanning electron microscopy, low-temperature nitrogen adsorption and Raman spectroscopy. The conductivity type of the films was checked by hot-point probe technique. In this work the conductivity of the samples was studied in the temperature range of 300?430 K, and the activation energies of conductivity were calculated. The effect of illumination (hv = 3.2 eV) on the conductivity of the samples was studied, and the photoconductivity and photosensitivity of materials were determined. The electrical and photoelectric properties of n- and p-type metal oxides were compared. The reported study was funded by RFBR according to the research project No. 18-32-20101.
Authors : M.Taeño1, D. Maestre1, J. Ramírez-Castellanos2,A. Cremades1, Pooi See Lee3
Affiliations : 1Dpto. Física de Materiales. Fac. CC. Físicas, Universidad Complutense de Madrid, Spain 2Dpto. Química Inorgánica I, Fac. CC. Químicas, Universidad Complutense de Madrid, Spain 3School of Materials Science and Engineering, Nanyang Technological University, Singapore
Resume : Nickel oxide (NiO) is one of the few known wide band gap p-type semiconductor oxides, so far. This material has recently demonstrated potential applicability in electrochemical capacitors , , smart windows and electrochromic devices , among others, . Controlling the chemical composition, size, morphology or structural defects, is essential in order to improve and broaden the applicability of this material. In addition, the incorporation of dopants, such as Sn,, can lead to improved electrical response. In this work, NiO nanoparticles undoped and doped with Sn content between 3 and 30 atomic %, have been synthesized by a hydrothermal process, using Ni(NO3)2·9H2O and SnCl2·2H2O as starting materials. The as-grown nanoparticles, with cubic structure, show good crystallinity and homogeneity in size, in all cases. Increasing Sn content leads to a smaller particle size and finally to the stabilization of SnO2 phase with rutile structure, as confirmed by X-ray diffraction (XRD). The characterization of the samples was performed by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), Raman Spectroscopy, Cathodoluminescence (CL), Photoluminescence (PL) and X-Ray Photoelectron Spectroscopy (XPS) at the Elettra synchrotron. Finally, the electrochemical analysis was performed by Cyclic Voltammetry (CV), Chronoamperometry (CA) and impedance spectroscopy. Promising values of specific capacitance (~ 300 F/g at 1 A/g) and cycling stability can be achieved for both undoped and Sn doped NiO used as supercapacitor electrode.  G.Cai, X.Wang, M.Cui, P.Darmawan, J.Wang, A.Eh, P. See Lee. Nano Energy.12, 258-267 (2015)
Authors : Pei Loon Khoo, Takayuki Koyama, Masanobu Izaki
Affiliations : Toyohashi University of Technology
Resume : The Shockley-Queisser limit power efficiency for a single bandgap solar cell is about 30%, due to its limited absorption range determined by its bandgap energy, which is unable to sufficiently match the wide solar spectrum. In order to overcome this, multi-junction and quantum dots PV devices which consist of different bandgaps have been proposed for the purpose, and the conversion efficiency over 30% has been achieved by the three- and four-junction PV devices. Recently, copper oxide semiconductors of 2.1-eV-p- Copper(I) Oxide (Cu2O) and 1.5-eV-p- Copper(II) Oxide (CuO) have attracted increasing attention as light-absorbing photoactive layers in photovoltaic devices  and as photocathodes in water-splitting system due to their non-toxicity, abundance, and low-cost. As a strategy of including several bandgaps in a photoactive device have reported the fabrication of Cu2O/CuO layer by electrodeposition of Cu2O followed by the formation of CuO on the top surface by annealing in air.  However, it was observed that scattering defects such as pores and voids were formed during the phase change during oxidation due to the transportation of ions, and fabrication of a layer with a reversed-order was not possible by that method. Here, we report a facile and flexible method capable of not only fabricating single Cu2O, CuO layers, continuously-stacked Cu2O/CuO, CuO/Cu2O bi-layers, but also multi-stacked layers, which were fully prepared by electrochemical deposition from a single solution. The substrates used were F-doped SnO2-coated soda-lime glass substrates. ZnO layers were first deposited on the FTO substrates from an aqueous solution containing 80 mmol/L zinc nitrate hexahydrate (Zn(NO3)2?6H2O) at -0.8 V at a temperature of 336 K for 0.5 C/ cm2. The single and continuously-stacked copper oxide layers were prepared by electrochemical depositions from the copper(II)-complex aqueous solution at 323 K. Single CuO layers were electrodeposited potentiostatically in a three-electrode-cell from 0.4 to 0.7 V while the Cu2O single layers were electrodeposited from -0.4 to -0.7 V. During the continuously-stacked electrodeposition of Cu2O/CuO, Cu2O/CuO bilayers and Cu2O/CuO/Cu2O/CuO, Cu2O/CuO/Cu2O/CuO multi-stacked layers with an automatic polarization system, a high-pressure mercury lamp was used for irradiation, and the potentials were set at 0.4 V and -0.4 V for the CuO and Cu2O respectively, with total electric charges of 1 C/cm2 and -1 C/cm2 for each oxide. Chronoamperometry curves were also recorded for each electrodeposition to show the change of deposition current with time. By controlling the potential of cathodic and anodic polarization from a single Cu(II)-complex aqueous solution, fabrication of single, bilayers and multi-stacked layers of Cu2O and CuO layers were successfully fabricated with their respective characteristic cubic lattice and monoclinic lattice, revealed by the XRD analysis. The CuO layer formed during the anodic polarization was induced by oxygen generation reaction which due to decreased pH value in the vicinity of the substrate surface, and the Cu2O layer was formed by reduction of Cu ion of 2+ to 1+ followed by the reaction with water molecules. The Cu2O and CuO layers also showed characteristic bandgap energy of 2.05 eV and 1.5 eV estimated from UV-vis measurements. FESEM cross-sectional observation revealed smooth, continuously layered structure without pores or voids and distinctive heterojunctions which showed clear boundaries of the layers. Optical characterization showed absorption edges characteristic to Cu2O and CuO at 608 nm and 832 nm respectively. External quantum efficiency (EQE) starting from 832 nm was observed for Cu2O/CuO/ZnO/FTO, indicating charge collections from both the Cu2O and CuO layer. In conclusion, single and continuously-stacked 2.05-eV-CuO and 1.5-eV-CuO photoactive layers have been successfully prepared by potentially-controlled electrodeposition from a single copper(II)-complex aqueous solution, which displayed photovoltaic performances in the EQE. This proven technique which enabled not only single-layered but also the multi-layered fabrication of copper oxides may open new doors to new applications in future ultra-low cost, high-performance photoactive layer in photocathodes and photovoltaics. References:  M. Izaki, T. Shinagawa, K. Mizuno, Y. Ida, M. Inaba, A. Tasaka, J. Phys. D, 40, 3326(2007).  P.L. Khoo, K. Satou, K. Nozaki, M. Izaki. 2018 J. Phys.: Conf. Ser. 1083 012030 Acknowledgments: This work was supported partly by a Grant-in-Aid for scientific research (19H02810) from the Japanese Society for the Promotion of Science.
Authors : Malte Martens, Joshua Fragoso, Alexander Colsmann
Affiliations : Karlsruhe Institute of Technology, Light Technology Institute (LTI), Engesserstrasse 13, 76131 Karlsruhe, Germany, Karlsruhe Institute of Technology, Material Research Center for Energy Systems (MZE), Strasse am Forum 7, 76131 Karlsruhe, Germany; Karlsruhe Institute of Technology, Light Technology Institute (LTI), Engesserstrasse 13, 76131 Karlsruhe, Germany, Karlsruhe Institute of Technology, Material Research Center for Energy Systems (MZE), Strasse am Forum 7, 76131 Karlsruhe, Germany; Karlsruhe Institute of Technology, Light Technology Institute (LTI), Engesserstrasse 13, 76131 Karlsruhe, Germany, Karlsruhe Institute of Technology, Material Research Center for Energy Systems (MZE), Strasse am Forum 7, 76131 Karlsruhe, Germany
Resume : Nickel oxide (NiOx) is often employed as a transparent, charge-selective, hole-transporting layer in optoelectronic devices such as (organic) solar cells, light-emitting diodes, photodetectors or transistors. Its main advantages over organic alternatives are a higher intrinsic stability and an enhanced energetic alignment at the layer interfaces. Nickel oxide precursors are used for solution processed NiOx layers with a low roughness and thickness. On the downside, they require a substantial conversion temperature of about 300°C that is not compatible with most (mechanically flexible) substrates and roll-to-roll printing. Laser-processing is a powerful tool for the selective manipulation of such thin-films. It is the ultimate enabler for precise structuring as well as depth-selective sample heating, and hence it can be used to trigger chemical processes in the NiOx precursor layer. Here, we present the fabrication of NiOx thin-films from a nickel acetate precursor solution and their implementation in organic solar cells. To avoid high processing temperatures, we demonstrate the conversion of the precursor to NiOx thin-films using a scanning UV-laser with ns-pulses. The process parameters were optimized for fast scanning and no damage to the NiOx-layer. We applied an oxygen plasma treatment to enable the manipulation of the work function of the layer and investigated the influence of the NiOx layer thickness on the optoelectronic device properties over a range from 10 nm down to below 2 nm, producing highly efficient solar cells.
Authors : Mario Urso1, Salvatore Gianluca Leonardi2, Nicola Donato2, Giovanni Neri2, Salvatore Petralia3, Sabrina Conoci3, Francesco Priolo1 and Salvo Mirabella1
Affiliations : 1 MATIS CNR-IMM and Dipartimento di Fisica e Astronomia ?Ettore Majorana?, Università di Catania, via S. Sofia 64, 95123 Catania, Italy; 2 Dipartimento di Ingegneria, Università di Messina, Contrada Di Dio, 98166 Messina, Italy; 3 STMicroelectronics, Stradale Primosole 50, 95121 Catania, Italy.
Resume : Gas sensing is receiving increasing attention driven by the need to ensure human safety by monitoring pollutant gases in the atmosphere such as NO2. Gas sensors based on metal oxides operating at room temperature are of great interest due to their energy saving and cost effective characteristics. Among the different materials investigated so far there is NiO, even if there are only a few reports regarding the low-cost fabrication of high-performance NiO-based sensors. In this work, we designed and fabricated a novel NiO nanofoam by a low-cost approach and applied it for the detection of NO2 at room temperature. Ni(OH)2 nanowalls were directly synthesized onto interdigitated contacts by chemical bath deposition and converted into a 3D network of NiO nanoparticles (30-50 nm in size) through thermal annealing. Sensing tests showed a high response to NO2 at room temperature even for the lowest concentration of 140 ppb. In addition, the sensor presented an excellent selectivity at room temperature vs high concentrations of acetone, methane, CO, CO2, H2. A model is presented to explain the improved NO2 sensing performances at room temperature. The unique characteristics of the NiO nanofoam make it a potential candidate also for other applications such as electrochemical (bio)sensing, catalysis, energy storage.
|15:55||Session IV. Oxyhydride and oxide nanomaterials. Chairs: Hiroshi Kageyama and Sanjay Mathur|
Authors : M. Wolff
Affiliations : Department of Physics and Astronomy, The Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
Resume : The presence of light elements in transition metals often plays a decisive role in defining the properties of materials for energy application. Examples in this context are the storage of hydrogen for stationary applications or tunable optical and transport properties. This presentation will emphasis the unique potential of advanced and new nuclear scattering methods to relate composition, microscopic structure and dynamics of metal hydrides and oxi-hydrides to macroscopic functionality, like transport or optical transmission. We will exemplify these capabilities with the following two examples: Vanadium can be grown with exceptional crystalline quality in thin films as well as in artificial alloys. This property allows to study finite size and proximity effects on hydrogen loading as well as on transport and optical properties. These insights provide fundamental knowledge for the design of future energy storage materials. Transition metal oxi-hydride have demonstrated to be photochromic under ambient conditions, and have a huge potential for application as window coatings for self-regulation of the heat transfer in and out of buildings. However, an optimized manufacturing protocol as well as the mechanism of the photochromic effect in such materials has not yet been established. In-situ compositional analysis during film deposition and the correlation of the optical properties to the composition and structure provide a route forward in this context.
Authors : Stephan Eijt 1; Diana Chaykina 2; Tom de Krom 1,2; Giorgio Colombi 2; Steffen Cornelius 2; Thomas Prokscha 3; Henk Schut 4; Werner Egger 5; Marcel Dickmann 5; Christoph Hugenschmidt 6; Bernard Dam 2
Affiliations : 1 Fundamental Aspects of Materials and Energy, Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629JB Delft, The Netherlands; 2 Materials for Energy Conversion and Storage, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, NL-2629HZ Delft, The Netherlands; 3 Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland; 4 Neutron and Positron Methods for Materials, Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629JB Delft, The Netherlands; 5 Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, D-85579 Neubiberg, Germany; 6 Physics Department & Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, D-85748 Garching, Germany.
Resume : Rare-earth metal oxyhydrides, including yttrium oxyhydride (YOxHy), are promising in view of their special photochromic properties. The present work focuses on elucidating the nature and role of hydrogen and vacancies in YOxHy by muon spin rotation (?SR) and positron annihilation spectroscopy (PAS). YOxHy thin-films are synthesized by reactive magnetron sputtering where the oxygen-to-hydrogen ratio is tuned by the deposition conditions. Zero field ?SR experiments on YH2-? and photochromic YOxHy thin films indicate the formation of ?+?H- pairs, that are located at tetrahedral sites. Transverse field experiments show that neutral muonium was formed in the semiconducting YOxHy films, but not in metallic YH2-?. In-situ illumination of YOxHy films leads to a clear reduction in muonium formation, that could be induced by photo-excitation of charge carriers during photochromic darkening, relaxing slowly upon bleaching. Positron Annihilation Lifetime Spectroscopy reveals the presence of vacancies in the YOxHy films. In-situ illumination of the films leads to an increase in positron Doppler Broadening S-parameter, plausibly related to generation of additional vacancies or changes in the charge state of the vacancies. Intriguingly, the S-parameter does not relax during optical bleaching under dark conditions, indicating persistent local rearrangements of vacancies and hydrogen ions. Possible roles of hydrogen and vacancies in the mechanism of photochromism in YOxHy will be discussed.
Authors : E.M. Baba 1,2, D. Moldarev 1,3, M. V. Moro 4, M. Wolff 4, D. Primetzhofer 4, M. Taeño 5, D. Maestre 5, A. Cremades 5, J. Montero 6, E.Ö. Zayim 2,7, S. Zh. Karazhanov 1
Affiliations : 1 Solar Energy Department, Institute for Energy Technology (IFE), Kjeller, Norway 2 Nanoscience & Nano Engineering Department, Istanbul Technical University, 34469 Istanbul, Turkey 3 Department of Materials Science, National Research Nuclear University, 115409 Moscow, Russia 4 Department of Physics and Astronomy, The Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden 5Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain 6Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, SE-75121 Uppsala, Sweden 7 Istanbul Technical University Faculty of Science and Letters, Physics Department, Istanbul 34469, Turkey
Resume : We present a study of gadolinium oxyhydride thin films prepared by in-air oxidation of reactively-sputtered gadolinium hydride coatings on glass substrate. The properties of the obtained films have been studied systematically by X-ray diffraction, UV-vis spectrophotometry, and variable angle ellipsometry. Under the influence of UV and blue light, the films exhibit a reversible decrease of their transmittance, recovering their initial transparent state once the illumination has stopped. In this work, we describe the possibility of optical band gap engineering in gadolinium oxyhydride by means of hydrogenation and oxidation processes. The dependence of the optical properties on film composition has been established by comparing spectrophotometric data together with chemical composition of the films obtained by ion beam-based techniques such as Elastic Recoil Detection Analysis and Rutherford Backscattering Spectrometry. The contraction of the gadolinium oxyhydride lattice has been observed upon illumination. Micro Raman measurements have been performed to correlate the light-induced change of materials properties with the surface.
Authors : M. Krunks, T. Dedova, I. Oja Acik
Affiliations : Laboratory of Thin Films Chemical Technologies, Department of Materials and Environmental Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia
Resume : Sustainable and cost-effective technologies are required for development of materials applicable in green buildings and vehicles for improved comfort and energy savings. Technologies used to date are frequently too expensive or complicated for large-scale industrial application. Recent achievements on development of smart materials by spray pyrolysis method for solar window applications, for in-door air and water cleaning will be overviewed. Examples on technology and properties of semi-transparent solar cells based on antimony chalcogenide thin film absorbers will be introduced. TiO2 thin films as an efficient risk-free material for air cleaning from volatile organic species, as well as ZnO and NiO nanostructured layers as promising photocatalytic coatings to degrade various pollutants in water will be presented and discussed. Chemical spray pyrolysis method offers a unique resource saving and rapid approach to fabricate thin films and nanostructured layers on large substrate areas for environmental and energy related applications.
Authors : D. Moldarev 1,2, M. V. Moro 3, E. M. Baba 1,4, J. Montero 5, C. C. You 1, D. Primetzhofer 3, M. Wolff 3, S. Zh. Karazhanov 1
Affiliations : 1 Solar Energy Department, Institute for Energy Technology (IFE), 2027 Kjeller, Norway; 2 Department of Materials Science, National Research Nuclear University MEPhI, 115409 Moscow, Russia; 3 Department of Physics and Astronomy, The Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden; 4 Nanoscience & Nano Engineering Department, Istanbul Technical University, 34469 Istanbul, Turkey; 5 Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, SE-75121 Uppsala, Sweden
Resume : Yttrium oxyhydride (YHO) belongs to a new class of materials with mixed oxide and hydride anions. This material demonstrates photochromic properties at ambient conditions, i.e. reversible changing of its optical properties under light illumination, making it attractive in many technological applications . In this work, we present a systematic study of the chemical composition of YHO films by means of Ion-Beam Analysis and correlate these results with optical properties, such as transmittance, band gap and photochromic contrast . The range of compositions within which YHO exhibits photochromic properties was also established. Studying the effect of thickness of the films on their properties revealed that thicker films feature a narrower band gap and show a stronger photochromic effect, which might be related to a larger crystallite size, as observed by XRD. Obtained results show which chemical composition and thickness of YHO films give better photochromic performance of the material.  T. Mongstad et al., ?A new thin film photochromic material: Oxygen-containing yttrium hydride,? Sol. Energy Mater. Sol. Cells, vol. 95, no. 12, pp. 3596?3599, Dec. 2011.  D. Moldarev et al., ?Yttrium oxyhydrides for photochromic applications: Correlating composition and optical response,? Phys. Rev. Mater., vol. 2, no. 11, p. 115203, Nov. 2018.
Authors : R. Martínez-Casado1, M. García-Carrión1, J. García-Fernández2, A. Torres-Pardo2, J. Ramírez-Castellanos2, E. Nogales1, J.M. González-Calbet2 and B. Méndez1
Affiliations : 1 Department of Physics of Materials, Faculty of Physical Sciences, University Complutense Madrid, 28040, Madrid, Spain 2 Department of Inorganic Chemistry, Faculty of Chemical Sciences, University Complutense Madrid, 28040, Madrid, Spain
Resume : Beta-gallia-rutile (BGR) intergrowths are interesting materials because of their 1-D tunnels, which are suitable hosts for cations. This type of structure is often found in materials for electrochemical devices such as batteries, fuel cells, and sensors. The theoretical analysis of the sodium titanogallate (Na-Ti-Ga-O) compounds, corresponding to three terms of the BGR series n = 5, 6 and 7 has been assisted by the use of ab initio calculations of the structure. The oxides; represent a challenge for standard implementations of Density Functional Theory (DFT). Generalized gradient approximations (GGA) functionals often underestimate the band gap, but the use of hybrid exchange functionals provides a qualitatively correct description of the structure, energetics and electronic properties for many different materials, and in particular, for oxides . The method adopted here is DFT using the screened hybrid exchange functional HSE. The HSE functional has the advantage that, partially corrects for electronic self-interaction and so yields qualitatively correct fundamental band gaps in wide band gap semiconductors [2,3]. The structure of the three terms of sodium gallium titanate have been characterized from an experimental and theoretical point of view for the first time. DFT calculations confirms the band gap obtained experimentally.  A. V. Krakau, O. A. Vydrov, A.F. Izmaylov, and G.E. Scuseria. J. Chem. Phys. 2006, 125, 224106.  B. G. Janesko, T.M. Henderson, G.E. Scuseria. Phys. Chem. Chem. Phys. 2009, 11, 443.  P. Pernot, B. Civalleri, D. Presti, A. Savin. J. Chem. Phys. A 2015, 119, 5288
|17:40||Session V. Posters. Chairs:|
Authors : A. Torrisi(1), P. Horàk(1), A. Cannavò(1), G. Ceccio(1), J. Vacik(1), J. Fara(2), P. Fitl(2), J. Vl?ek(2), M. Vrnata(2)
Affiliations : (1)Nuclear Physics Institute, AS CR, Hlavnì 130, 25 068 Husinec-?e?, Czech Republic (2)University of Chemistry and Technology, 166 28 Prague, Czech Republic
Resume : Metal oxide based gas sensors (MOS) found a wide application as modular parts in microelectronic devices due to their technological compatibility, low cost and outstanding sensing capabilities to different chemical species. The functionality of such chemiresistors consists of changing the electric resistance/impedance of a semiconducting sensitive layer when gases with either oxidizing or reducing properties appear in the surrounding atmosphere. Earlier, the majority of the investigated chemiresistors were based on single phase, homogenous semiconductors. Combination of two different species and hence implementation of heterojunctions (HJs) to chemiresistors offer a way how to increase the sensor performance, especially the sensitivity of the sensor. In this work, chemiresistors based on CuO-TiO2 acting as p-n heterojunction were developed. The thin sensitive layers were deposited by a two-step process. Cu-Ti thin layers were prepared by ion beam sputtering using Ar ion beam and, subsequently, oxidized by the thermal annealing in air at 400 °C, for 7 h. The stoichiometry of the metallic films was analyzed by the Rutherford Back-scattering method (RBS) using 2 MeV ?-particles and the oxidation degree was studied by the Nuclear Reaction analysis (NRA) using 3.046 MeV ?-particles. The gas sensing properties of the oxidic thin films (deposited on prefabricated substrates containing interdigital electrodes) were analyzed in atmosphere containing 1000 ppm of MeOH or 10.6 ppm of NO2.
Authors : Yang Luo (a, b), Shili Zheng (a), Paul K Chu (b)
Affiliations : (a) CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China (b) Department of Physics and Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong, China
Resume : Accumulation of high-arsenic fly ash (HAFA) poses a serious environmental threat due to the toxicity. In this work, a novel graphite felt (GF) cathode modified with the nanoscale MoS2/reduced graphene oxide (rGO) heterojunction is prepared by a PTFE-bonding method for efficient oxidative dissolution of As(III) in HAFA. By taking advantage of the p-n junction characteristics of the heterojunction and appropriate hydrophobicity of the PTFE coating, the modified GF efficiently utilizes both dissolved O2 and gaseous O2 in the 2e- oxygen reduction reaction (ORR). Our theoretical results indicate that gaseous O2 adsorbs stably on sulfur vacancies and is reduced by electrons transmitted from rGO. Experimentally, the modified GF shows superior ORR catalytic activity as exemplified by a high peak current density of 8.41 mA?cm-2 and onset potential of -0.12 V vs. SCE. The ?OH generated by an autocatalysis mechanism promotes As(III) oxidization in detoxification of HAFA resulting in As removal of 96.1% in 135 min. The modified GF with excellent stability and durability has immense industrial prospect with regard to detoxification of HAFA and treatment of other types of As-containing hazardous wastes.
Authors : Martin Timusk, Triin Kangur, Martin Järvekülg
Affiliations : University of Tartu, Institute of Physics, W. Ostwaldi Str. 1, 50411 Tartu, Estonia
Resume : We describe a novel method of preparation of silica aerogel powder with uniform particle size of ~1-3 mm. The method is significantly less time-consuming and requires less solvents than any previously known method. In this method no expensive equipment nor toxic drying-control chemical additives like formamide or N-N´-dimethyl formamide are required, making it potentially the cheapest method for producing aerogel powders. This method relies on neither super- nor subcritical processing and by that opens up a new vista for aerogel synthesis. The measurements show that the aerogel powder has specific surface area of 610 m2/g (BET), average pore diameter of 12 nm and porosity of approx. 80-89%. The density of the pile of powder, if shaken to densely fill the container, is ~0.22 g/cm3 and the estimated density of the single powder particle is < 0.3 g/cm3. The material is obtained in a straightforward manner and at low cost. Aerogel powders are usable as functional additives in advanced thermal insulation composites.
Authors : Shehab A. Mansour 1,2, Ibrahim Eldafatry 2, Ragab A. Elsad 2, El-Sayed M. Farag 2
Affiliations : 1 Advanced Materials/Solar Energy and Environmental Sustainability (AMSEES) Laboratory, Menoufia University, Faculty of Engineering, Shebin El-Kom, Egypt 2 Basic Engineering Science Department, Faculty of Engineering, Menoufia University, Shebin El-Kom, Egypt
Resume : The cool pigments (PGs) based on metal oxides are promising for commercial cool painting applications, due to their high reflectance for near infrared (NIR) radiation, which considered the direct consequence of heat up in solar radiation. Indeed, the darker colors are preferred in real usage for their aesthetics. Nevertheless, the addition of the colored element to white PGs lead to limitation of their high reflectivity to NIR radiation. Many research works were done to synthesize the colored PGs based on nanostructured metal oxides to increase the number of reflectance points, which improves the scattering of radiation and compensates the limitation of reflectivity due to the addition of colored elements. In fact, amorphous materials have a high surface area due to their high-roughness surface. To date, amorphous nanosized TiO2 was not used in pigment applications. In this respect, we realized Cr:TiO2 nanosized amorphous with Cr concentrations up to 25 Cr at. % at 100oC as well as crystalline structure ones at different annealing temperatures up to 700oC. The diffuse reflectance measurement according to the ASTM (G173-03) revealed high NIR solar reflectance (R*) for the amorphous PGs in comparison to the crystalline PGs. The obtained values of R* of amorphous PGs exhibited small reduction from 81 to 72.5% with the increase of Cr concentration, However, dramatic reduction in R* from 82.1 to 20.4% and from 93.5 to 20.87% for crystalline PGs annealed at 500oC and 700oC, respectively. The obtained results will be interpreted using the variation of the surface area and porosity as well as microstructure of the investigated PGs. The obtained results enable to fabricate novel and cost effective cool-colored nanopigments based on amorphous TiO2.
Authors : 1. Junghyo Nah 2. Min Hyung Lee
Affiliations : 1. Dept. of Electrical Engineering, Chungnam National University, Daejeon, South Korea 2. Dept. of Applied Chemistry, Kyung Hee University, Yongin, South Korea
Resume : One of effective approaches to obtain high performance water splitting device is to form desirable band bending at the interface between the charge generation material and electrolyte. For this purpose, ferroelectrics materials can be promising candidate, attributed to the induced polarization by applying high electric field. In this way, the modulated band bending along with desired direction overcomes the intrinsic property of anode or cathode in water splitting. Herein, we selected semiconducting and ferroelectric zinc oxide (ZnO) nanomaterials by doping with lithium and vanadium. The modulated spontaneous polarization in doped ZnO as photoanode was systematically investigated, varying the valence band bends upward or downward at the electrolyte interface. Consequently, the solar-tohydrogen (STH) efficiency using positively-polarized photoanode improved up to up to ~200 %, thanks to the favorable band bending for the generated hole transfer to electrolyte in comparison to the negatively-polarized one. The approach introduced using ferroelectric ZnO is simple, effective, and suitable way to design the high performance photoelectrochemical device. For the future work, also, the ferroelectric ZnO in core-shell design can be easily adopted by combining desirable anode material.
Authors : Xiao Sui, Yuan Chen
Affiliations : The University of Sydney
Resume : Graphene oxide (GO) can be processed into carbon membranes with unique water permeability and molecular selectivity. Metal-organic frameworks (MOFs) have been proposed as filler materials to enhance water permeability of laminar GO-based carbon membranes. However, it remains unclear how the enhancement arises. Herein, we combined experimental and molecular simulation studies to provide critical insights into the water transport behaviors of GO/MOF composite membranes. The water permeability enhancement was found to be directly correlated to the increase in the average interlayer spacing between GO nanosheets. The simulation results indicate a slower water transport through nanochannels in MOFs than in nanochannels formed by GO nanosheets. A small amount of MOF particles only serves as a blockage in laminar GO membranes, suppressing their water permeability. In contrast, a large amount of MOF particles increases the interlayer spacing between GO nanosheets and creates very fast water transport stretches. Besides, some large gaps are formed between non-smooth MOF particles and GO nanosheets, adding supplementary water channels to deliver higher water permeability. We envision a shift in future research direction to exploit the selective adsorption capacity of MOFs other than leveraging them as fast water transport channels to realize their potential water treatment applications.
Authors : Yonghee Yoon, Soyoung Kim, Cheolhwan Jeong, Sunyoung Lee, Jaegyoung Gwon, Wonhee Lee
Affiliations : Sejong University, National Institute of Forest Science
Resume : A mechanistic study on the synthesis of mesoporous titania films with templating cellulose nanocrystals (CNCs) through a sol-gel process as influenced by CNC content and calcination temperature was made in this work. During calcination, the rutile phase of titania was transformed into the anatase phase with the use of templating CNCs. The CNCs provided heterogeneous nucleation sites for the crystallization of titania, resulting in the formation of more and smaller crystallites with sizes down to 8.8 nm. With the use of CNCs and calcination, specific surface area of titania films increased up to 221.6 m2/g, depending on actual CNC content. All titania films present a monomodal pore size distribution with the pore width varying between 2.5 to 15 nm. The average width of pores originated from the sacrificial CNCs was affected mostly by the calcination temperature rather than CNC content. The content of templating CNCs significantly affected surface area, pore volume, and crystallite size of the film. The degree of absorption in the visible light region consistently increased with increases in the CNC content, suggesting that the CNC-templated titania films can efficiently provide more photocatalytically active sites for light absorption. The morphology, porous structure, phase composition, and optical properties of titania films are controlled by manipulating the process conditions such as CNC content in precursor and calcination temperature.
Authors : Rei Hatori1, Yoshikazu Suzuki2
Affiliations : 1 Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-8573, Japan;2 Faculty of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-8573, Japan
Resume : Al2O3/3Y-ZrO2-based ceramic composites generally have very high strength and high chemical stability. Here, we focused on this composite material and aimed for the production of a microfiltration membrane that has high mechanical strength and can remove large sized viruses around several hundred nanometers. In this study, five types of mixed powders were prepared by a wet ball mill by changing the mass ratio of Al2O3 and 3Y-ZrO2. The powders were molded into a disk by uniaxial pressing, and the disk was sintered at 1200, 1300, 1400 and 1500°C to prepare a disk filter. The characteristics of the filters were evaluated by SEM, XRD, mercury intrusion method, and filtration test. Dead-end filtration was selected for the filtration test. It was found that the filter made of the Al2O3/3Y-ZrO2 composite sintered at 1200-1300°C showed much higher filtration performance than that of monolithic Al2O3. It was found that the filter performance of the composite material filter increased as the mass ratio of 3Y-ZrO2 increased.
Authors : L. Andronic 1, A. Banciu1,2, S. Zh. Karazhanov 2
Affiliations : 1 Department of Product Design, Mechatronics and Environment, Transilvania University of Brasov, Brasov, Romania 2 Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway
Resume : Although titanium dioxide exhibits excellent photocatalytic properties, it can absorb between 3-7% of the sunlight. To enhance light absorbing properties of the material one needs to dope it with impurities that create midgap states that absorb sub-bandgap photons. An alternative way is preparing composite or hybrid material by mixing TiO2 with another material with better light absorbing capability than TiO2. Photocatalytic properties of Si are not as good as that of TiO2; however, Si absorbs more than 30% of sunlight. Here we report about synthesis, characterization, and study of photocatalytic properties of TiO2/Si composite nanoparticles. We report about the structural, optical, morphological, vibrational, and photocatalytic properties of the nanoparticles. From the study of morphological properties, we have established the formation of composite nanoparticles. Structural studies showed the formation of anatase phase. From the studies of optical properties, we have found that the composites absorb not only ultraviolet but also a visible part of the sunlight. Enhancement of photocatalytic property of the composite has been reported.
Authors : Beatriz Rodríguez, Pedro Hidalgo, Bianchi Méndez and Javier Piqueras
Affiliations : Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040-Madrid, Spain
Resume : We report the rapid synthesis of MoO3 layered plates when a current flows through a molibdenum wire. The works paves the way to fast and low cost synthesis of van der Waals materials with promising applications in energy devices, among others. The results show that an electrical current of about 4.5 A, which heat the Mo wire up to 450-500 ºC, during 2 ? 4 minutes is suitable to achieve the formation of high number of plates in the central part of 5 cm length Mo wires . The structural analysis by means of Raman spectroscopy and Electron Backscattered Spectroscopy (EBSD) reveal that the plates are orthorhombic MoO3 with (010) orientation of the surface planes. The growth mechanisms are discussed in terms of the electromigration and local oxidation processes at the surface of the wire . In order to study the charge diffusion during the growth, external electric fields are applied either parallel or perpendicular to the current flow. References  A. F. Mallet, T. Cebriano, B. Méndez and J. Piqueras, Phys. Stat. Sol. (a), 215, 1800471 (2018).  S. K. Lin, Y. C. Liu, S. J. Chiu, Y. T. Liu and H. y. Lee, Sci. Rep. 7, 3082 (2017).
Authors : Yesul Jeong, Shin Kim, Min-Ouk Park, Pung-Keun Song and Jang-Hee Yoon*
Affiliations : Busan center, Korea Basic Science Institute (KBSI), Republic of Korea, Busan 46742 Pusan National University(PNU), Republic of Korea, Busan 46241
Resume : Recently, industrial wastewater is being discharged in large quantities due to the development of industry and this wastewater contains a various heavy metal ion. Exposure to high levels of trace metal ions causes a variety of health and environmental problems. These toxic species accumulated in the human body through the water source have a low rate of clearance. In generally, Ir, Au Ag and Hg electrodes have been used for heavy metal ion sensors (HMIS). However, there is still problem to be solved. For example, the Ir, Au, Ag electrodes have low sensitivity, whereas Hg electrode have toxicity and volatility. Boron-doped diamond (BDD) is now having great attention for promising electrodes because of its good electrical conductivity, low background current, long lifetime and non-toxicity. In this study, processing condition for fabrication of BDD electrodes was optimized, and consequently its electrochemical properties was investigated. The BDD electrodes, deposited by hot filament chemical vapor deposition (HFCVD) on Si substrate using optimized processing condition, results in the enhanced detection sensitivity for heavy metal ions. In addition, it was observed that pre-treatment on substrate promotes crystal growth and film uniformity of resulting BDD thin films, leading to an increase in the electrochemical performance of BDD electrodes. HMIS adopted BDD electrode was displayed high sensitive response and wide potential window range of -1.7 V to 1.6 V with the detection limit of 0.001 mg/L to 0.01 mg/L ±5 % about heavy metal ions [Cd (II), Pb (II), Cu (II)].
Authors : Javier García-Fernández, Javier Bartolomé, Alamudena Torres-Pardo, Ruth Martínez, Julio Ramirez-Castellanos, Ana Cremades, Jose María González-Calbet
Affiliations : Javier García-Fernández; Alamudena Torres-Pardo; Julio Ramirez-Castellanos; Jose María González-Calbet: Departmento de Química Inorgánica, Facultad de Químicas, Universidad Complutense de Madrid, 28040 Madrid, España Javier Bartolomé, Ruth Martínez, Ana Cremades: Departmento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, España
Resume : Transparent semiconducting oxides (TCO) constitutes a large field of research due to its applications as transparent electrodes in transistors, flat panel displays, solar cells, sensors, etc. . In this work, Zn7In2-xMxO10 (M = Ga and Al, and 0?x?0.5) materials have been prepared by the ceramic method. The microstructure of the materials was elucidated by means of X-ray diffraction (XRD), electron microscopy (HRTEM and STEM), luminescence and Raman spectroscopy. HRTEM images show that the undoped materials are formed by ordered layers of InO2- octahedra sharing edges with blocks of (InZnk)Ok+1+ composition along the c-axis, in such a way that the (001) plane of the ZnO structure and the (111) In2O3 plane are epitaxially equivalent to the (001) plane of ZnkIn2Ok+3 . The characteristic modulation of this homologous series (a zig-zag pattern due to the incorporation of indium atoms within the wurzite block) is also visualized . The effects of In3+ substitution by Ga3+ and Al3+ in the crystal structure and luminescent properties of the Zn7In2-xMxO10 (M=Ga, Al with x= 0.25, 0.5, 0.75 and 1.0) oxides are studied by Raman and luminescence spectroscopies. Advanced TEM and various diffraction techniques have been used to confirm the formation of the complex structures and to study the preferential sites for Ga3+ and Al3+ cations incorporation. The dopants induce new defect levels in the band gap of IZO structure as probed by luminescence techniques. A new emission centered at 1.9-2.1 eV has been found in the Ga3+ and Al3+ structures, and its origin and relation with this structural feature is discussed in this work, and explored by DFT simulation.
Authors : I. Hontecillas, R. Ranchal
Affiliations : Dpt. Física de Materiales, Fac. CC. Físicas, Universidad Complutense de Madrid, Madrid 28040, Spain.
Resume : Exploring new exchange-biased systems is fundamental for the development of innovative spintronic devices. There has been a great interest in the development of magnetic materials with large perpendicular magnetic anisotropy (PMA) for non-volatile random access memories. Magnetic structures with a tilted magnetic anisotropy [1-3], i.e. the anisotropy axis is tilted a certain angle with respect to the out of plane (OOP) direction, appeared as a solution to the large coercivity and switching fields typically observed in PMA systems. We propose the combination of an antiferromagnetic material with PMA and a ferromagnet with a certain OOP component of the magnetization in order to achieve a new system with tilted magnetic anisotropy. In our approach, we have magnetically coupled Cr2O3 with sputtered FeGa layers with different thickness ranging from 20 to 180 nm. Since the Neel temperature of Cr2O3 is slightly above room temperature, we have studied the phenomenon of exchange-bias at 300 K. For a proper combination of thickness, hysteresis loops are shifted in the horizontal axis when the magnetic field is applied perpendicular to the sample plane. Nevertheless, the exchange-bias is negligible when measuring in the sample plane. Therefore, despite the small OOP component of FeGa, it seems to enable some exchange-bias phenomenon.  L. You et al., PNAS 2015, 112, 10310.  I. N. Krivorotov et al., Science 2005, 307, 228.  S. I. Kiselev et al., Nature, 2003, 425, 380.
Authors : Renata Karpicz a), Katsiaryna Chernyakova b), Danielis Rutkauskas a), Igor Vrublevsky b)
Affiliations : a) Center for Physical Science and Technology, 231 Savanoriu Ave., LT-02300 Vilnius, Lithuania; b) Belarusian State University of Informatics and Radioelectronics, 6 P. Brovka Str., 220013 Minsk, Belarus
Resume : Oxide materials attract much attention due to their application as absorbents, catalyst supports, and as the parts of electronic and optical devices. ?- and ?-Al2O3 layers because of their biocompatibility and high chemical resistance are also of a great demand. Porous alumina films can be easily obtained by Al anodizing. However, the as-received samples are amorphous, and therefore, fragile and hard to handle. To improve the mechanical properties of the films the samples can be heat treated (T = 900?1400 °C), in this case crystalline alumina will be formed. In the present study by fluorescence microscopy we investigated the changes in crystalline structure of the sulfuric acid anodic alumina films during their heat treatment in O2 and Ar atmosphere. The crystallization start was detected by the appearance of the florescence peaks at 670, 690 and 710 nm. When samples were heat treated in Ar no crystallization occurred up to 1100 °C. For heat treatment in O2 the crystallization took place at 900 and 1100 °C corresponding to the formation of ?- and ?-Al2O3, respectively, that is 100 °C lower than it was determined for sulfuric acid anodic alumina. So, heat treatment of the anodic alumina in O2 promotes its crystallization.
Authors : M. Taeño, D. Maestre, and A. Cremades
Affiliations : Departmento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040, Madrid, Spain
Resume : Despite the promising application of nickel oxide (NiO) as gas sensors, electrochromic devices, supercapacitors or smart windows , less has been done so far in the fabrication of elongated micro- and nanostructures, the use of which can widen the applicability of this p-type material in optoelectronic devices. In this work, a catalyst free vapor?solid method has been used to fabricate Sn doped NiO elongated micro and nanostructures, using a controlled mixture of metallic Ni and either Sn or SnO2 as precursors. Thermal treatments at temperatures of 1400 oC under a controlled Ar flow lead to the formation of a large concentration of NiO microwires and rods with good crystallinity and lengths of tens of microns. Raman spectroscopy and X-ray diffraction (XRD) confirm that the microwires consist of NiO with cubic rock-salt structure. XPS measurements acquired at the Elettra synchrotron confirm the presence of Sn as a dopant, in a low concentration, which involves variable Ni3 /Ni2 ratio. The microwires show emissions at 2.0 eV and 2.5 eV, as measured by photoluminescence, and exhibit waveguiding behaviour.  C. Liu, C. Li, K. Ahnemd, Z. Mutlu, C.s. Ozkan and M. Ozkahn. Sci. Reports 6, 29183 (2016)
Authors : J. Dolado, P. Hidalgo and B. Méndez
Affiliations : Department of Materials Physics. Faculty of Physics, Complutense University of Madrid, E-28040 Madrid, Spain
Resume : Zn2GeO4 is a novel transparent conductive oxide material, with an ultra-wide band gap of 4.5 eV, and rather good electrical conductivity . Zn2GeO4 nano- and microwires grown by a thermal technique show two intense emission bands centered in the UV and VIS region, respectively . With the intention of better understanding the mechanisms of luminescence, we have studied the correlation between luminescence and structural properties in undoped , Mg2+ or Li1+ doped samples. The different ions could modify the optical properties by their interaction with the native defects of this semiconductor depending on the position of these ions into the crystalline lattice. But, because of these ions have a very low ionic radii, these modifications of the optical properties could be done without introducing major distortions in the lattice, providing us a very important information on the properties of native defects. Photoluminescence (PL) and photoluminiescence excitation (PLE) measurements at very low temperatures, from 4K up to RT, will provide us more information about these recombination mechanisms. In addition, optical confinement effects have been observed, what could be further exploited in the design of optical resonators. The waveguiding behavior of the microrods has been assessed using a 325 nm laser as light source and analyzing the transmitted light along the structure. References 1. Mizoguchi, H.; Kamiya, T.; Matsuishi, S.; Hosono, H., A germanate transparent conductive oxide. Nature Communications 2011, 2, 470. 2. Hidalgo, P.; López, A.; Méndez, B.; Piqueras, J., Synthesis and optical properties of Zn2GeO4 microrods. Acta Materialia 2016, 104, 84-90. 3. Dolado, J.; Hidalgo, P.; Méndez, B., Correlative study of vibrational and luminescence properties of Zn2GeO4 microrods. Physica Status Solidi (a) 2018, 215(19), 1800270.
Authors : L. Khomenkova1,2, X. Portier1, C. Labbé1, J. Cardin1, C. Frilay1, P. Marie1, F. Gourbilleau1
Affiliations : 1) CIMAP Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, 6 Boulevard Maréchal Juin, 14050 Caen Cedex 4, France; 2) V. Lashkaryov Institute of Semiconductor Physics at the NASU, 45 Pr.Nauky, 03028 Kyiv, Ukraine
Resume : In this work, the effect of annealing treatment on the structural and optical properties of thin Er2O3 films is studied. The films were grown by thermal atomic layer deposition on Si substrates kept at 300°C using Er(CpMe)3 as a precursor. Then, they were subsequently annealed at 500-1100°C in nitrogen flow for 30 min and investigated by means of spectroscopic ellipsometry, FTIR, XRD and TEM methods. As-deposited and annealed at T=500°C films were found to be amorphous. The increase of annealing temperature from 600 to 900°C stimulated the densification and crystallization of the films that is evidenced by the increasing of refractive index and film thinning as well as by the sharpening of Er-O related FTIR peaks. Further temperature rise up to 1100°C caused the decreasing of refractive index and the appearance of additional FTIR signal related to Si-O-Er vibrations. This Er silicate phase can be formed due to a diffusion of silicon atoms from underlying substrate. XRD and TEM studies of annealed films supported this conclusion. The approaches allowing to stabilize Er2O3 structure and to preventing Si diffusion in the film volume are discussed. This work was performed in the frame of LUMIERE project (Enhancement of the luminescence of rare-earth ions for photovoltaic applications), which has been funded by the Normandy Region and by the European Regional Development Fund (ERDF) (Fonds Européen de DEveloppement Régional (FEDER)).
Authors : Chang Chuan You1, Dmitrii Moldarev1,2, Smagul Zh. Karazhanov1
Affiliations : 1Department for Solar Energy, Institute for Energy Technology, NO-2027 Kjeller, Norway 2Department of Materials Science, National Research Nuclear University MEPhI, 115409 Moscow, Russia
Resume : Transparent yttrium oxyhydride (YHO) thin films exhibit photochromic effect under ambient conditions . The optical transmission in such materials can be strongly modulated upon absorption of electromagnetic radiation. The transparency of the film can be typically reduced from ? 80 ? 90 % in the clear state to 40 ? 50 % in the photodarkened state in the visible and infrared regions of the light spectrum. The photodarkened YHO film bleaches back to its initial yellow clear state upon dark annealing at room temperature and atmospheric pressure. This switchable optical property is interesting for technological applications, such as enegy-saving smart windows and sensors . In this work, we have prepared photochromic uniform, transparent YHO thin films with different thicknesses and optical energy band gaps on glass substrates by using reactive magnetron sputtering deposition. We investigate how the photochromic performance is affected when the light intensity and wavelength are varied. Analysis of the time-resolved optical transmission data show that the coloration process can be well described by a logarithmic decay function, indicating a rapid coloration speed in the beginning of the photochromic reaction followed by a slower coloration speed with increasing illumination time. Moreover, the kinetics of the bleaching process will also be discussed.  T. Mongstad et al., A new thin film photochromic material: Oxygen-containing yttrium hydride, Sol. Energy Mater. Sol. Cells. 95 (2011) 3596?3599.  P. Bamfield, Chromic phenomena: The technological applications of colour chemistry, The Royal Society of Chemistry, Cambridge, 2001.
Authors : Chengcheng Zeng, Jianhu Zhang, Feiyan Gong
Affiliations : Institute of Chemical Materials, CAEP, Mianyang, China
Resume : Poor compatibility between aluminum nanoparticles and polymeric binders and low efficiency of aluminized explosives is a basic issue we face in the study and application of aluminized explosives. Surface grafting is an effective route to improve the interfacial compatibility. However, traditional coating has a negative influence on integrity of the shells and reactivity of aluminum nanoparticles. It is difficult to deliver energy when explosives and aluminum powders separate as individual islands. Based on the construction of composite microstructure of energetic materials, the aluminum nanoparticles, which are grafted by covalent modification, will be grafted onto explosive crystal to form ordering sore-shell structures. Firstly, intermediates with specific functional groups connect energetic molecular GAP and nano-aluminum. Then, modified aluminum particles are assembled on explosive crystal HMX to prepare core-shell aluminized composites, to realize efficient release of energy. The results show that GAP shell with a thickness of about 2nm is formed on the surface of nano-aluminum particles, which makes the surface change from hydrophilic to hydrophobic, and also increases the compatibility with fluoropolymer. At the same time, the existence of GAP can effectively prevent the inactivation of aluminum powder in the granulation process with hot water, and the thickness of shell is inversely proportional to the content of aluminum powder in the reaction. Through ignition experiments, the energetic groups in GAP and the promotion of better contact with fluoropolymer can improve the reaction heat release rate and the utilization rate of aluminum powder. The core-shell aluminum-containing composite was successfully prepared by pre-modification of SEM photos. The mechanical test results indicates that the modulus of core-shell aluminum-containing composite is higher than that of physical blends under the same conditions, and the creep resistance of the composites is also better. In the ignition experiment, the ignition time of explosive particles coated with GAP-grafted aluminum shells is shorten, and the combustion stability reaction is sufficient.
Authors : Hiromi Eba, Maho Ando, Yuto Yamaguchi, Kengo Kobayashi, Chinami Suzuki
Affiliations : Tokyo City University
Resume : An electric furnace reducing slag provided by an electric arc-furnace steelmaker was treated with hydrochloric acid, separated into an insoluble component and an eluted component, and the synthesis was performed using each as a raw material. XRD measurement of the reduced slag showed that the components were mainly oxides, silicates and carbonates of Fe, Ca, Mg and Al. It was confirmed by XRF analysis that these metal ions were eluted by acid treatment. The precipitate formed by adding NaOH to the slag leaching solution was ripened at 50°C and then XRD measurement of the product was carried out. As a result, diffraction lines of Ca-Al-Cl based hydrocalumite and Ca-Al-Si based hydrogarnet (Katoite) were detected. The amount ratio of both hydroxides varied with aging time. It seems that some of Ca and Al are replaced by Mg and Fe in these crystals. The hydrocalumite is a kind of layered double hydroxide (LDH) which is known to have anion exchange ability. The solid phase remaining after treating the reduced slag with concentrated hydrochloric acid was analyzed by XRF and it was confirmed that Si was concentrated. XRD of the solid phase showed a halo pattern, that is, amorphous silica was obtained. By adding NaAlO2 and NaOH to this solid phase and conducting a hydrothermal treatment at 90°C, a Na-LSX zeolite (Na-low silica X) was obtained. SEM observation showed mesopores on the particle surface. Using this zeolite for Cs adsorption test from CsCl aqueous solution, it showed a high adsorption amount. No such pore was generated in Na-LSX synthesized from SiO2 reagent free of impurities. Therefore, it seemed that the impurities contained in the reduced slag contributed to the formation of mesopores.
Authors : Zdenek Remes (1), Yu Ying Chang (1,2), Neda Neykova (1), Maksym Buryi (1), Julia Micova (3) and Hua-Shu Hsu (4)
Affiliations : (1) Institute of Physics CAS, Cukrovarnicka 10, 16200 Praha 6, Czechia; (2) Faculty of Biomedical Engineering CTU, Nam. Sitna 3105, 27201 Kladno, Czechia; (3) Institute of Chemistry SAS, Dubravska cesta 9, 84538 Bratislava, Slovakia; (4) Department of Applied Physics, National Pingtung University, 4-18, Minsheng Road, Pingtung, 90044, Taiwan
Resume : Zinc oxide thin films and nanostructures are a subject of a broad attention due to interesting optical, electric, piezoelectric and ferromagnetic properties. The high surface-to-volume ratio and related size effects impose challenges for energy conversion or sensing applications i.e. in solar cells, optoelectronic devices, electrochemical energy storage, gas sensors and biomedical applications. In our previous work we have already shown the role of the native point defects and oxygen vacancies. In our group we grow the perpendicularly oriented ZnO nanorods under hydrothermal conditions at 90°C with and without UV ligh bias on the nominally undoped ZnO thin film deposited by laser sputtering or DC reactive magnetron sputtering of Zn target in the gas mixture of argon and oxygen plasma. The different morphological structures were visualized and analyzed by scanning electron microscopy (SEM). The crystalline configuration and the structural quality were investigated by X-ray diffraction and Raman spectroscopy. The surface properties of ZnO nanorods were examined by X-ray photoelectron spectroscopy. The defect-related photoluminescence observed as a broad band at wavelengths 550?650 nm was significantly reduced after plasma hydrogenation whereas the exciton-related peak at 378 nm increased significantly. Thus, using hydrogen plasma instead of high temperature annealing, we have achieved the defect passivation at room temperature. The strong suppression of the F+?related defects was observed after plasma hydrogenation using the electron paramagnetic resonance (EPR). This makes evidence for strong influence of the surface defects on the photoluminescence properties of the ZnO nanorods This work was supported by the Ministry of Science and Technology of Taiwan under Grant Nos. M-153-001-MY3, 107-2119-M-153 -001. This work was supported by the CSF project 19-02858J and by the Operational Programme Research, Development and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (Project No. SOLID21 - CZ.02.1.01/0.0/0.0/16_019/0000760).
Authors : S. Prucnal1, R. Gago2, D. Esteban-Mendoza2, I. Jiménez2, O. C. Aktas3, F. Faupel3, S. Zhou1
Affiliations : 1Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, 01328 Dresden, Germany; 2 Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, E-28049 Madrid, Spain; 3 Institute for Materials Science Chair for Multicomponent Materials Faculty of Engineering Christian-Albrechts-University of Kiel Kaiserstraße 2, 24143 Kiel, Germany;
Resume : Semiconducting metal oxides often exhibit high photocatalytic efficiency (PE) and, among them, the anatase-TiO2 (A-TiO2) is the most promising material for the water splitting under sun light illumination. The PE of TiO2-based materials mainly depends on the surface state density, Fermi level position, band gap and crystalline structure (anatase, rutile, brookite). Here, we present the optical, electrical and structural properties of A-TiO2 thin films made by RT magnetron sputtering followed by ms-range flash lamp annealing (FLA) in N2 ambient. X-ray diffraction (XRD), X-ray absorption near-edge structure, and Raman spectroscopies reveal the transformation from amorphous to single-phase A-TiO2 during FLA for 20 ms. The FLA energy density was in the range of 65 to 110 Jcm-2, corresponding to peak temperatures in the range of 500oC to 1100 oC, respectively. XRD and scanning electron microscopy shows that with increasing FLA energy the average crystal size of the A-TiO2 increases from a few nm?s up to ~200 nm after annealing at energy density of 110 Jcm-2. On the other hand, the optical band-gap, as determined by spectroscopic ellipsometry, remains at ~3.4 eV. The bleaching of methylene blue under irradiation with a high-intensity light-emitting-diode (4.5 W/cm2) at 365 nm has been used to test the photoactivity of the samples after FLA. The PE of the samples is enhanced with increasing the annealing temperature, which we assign to the engineering of surface states and carrier lifetime upon FLA in N2 ambient.
Authors : Yael Templeman1, Sergey Rogozhkin2,3, Artem Khomich2, Aleksander Nikitin 2,3, Malki Pinkas4, Louisa Meshi1
Affiliations : 1 Department of Materials Engineering, Ben Gurion University of the Negev, POB 653, Beer Sheva 84105, Israel; 2 Institute for Theoretical and Experimental Physics named by A.I. Alikhanov of National Research Centre «Kurchatov Institute», 117218 Moscow, Russia; 3 National Research Nuclear University «MEPhI», 115409 Moscow, Russia; 4 Nuclear Research Center-Negev, P.O. Box 9001, Beer-Sheva, Israel
Resume : Oxide dispersion strengthened (ODS) steels exhibit superior mechanical properties and irradiation resistance due to nano-sized oxides, highly dispersed in the metallic matrix. These The mechanical properties are affected dramatically by the structure, composition, size and density of the nano-sized oxides. Despite numerous reports on the characterization of these oxides, ambiguity regarding their composition, crystallographic structure, and orientation relationship with the matrix remains. In the present study, characterization of the crystallographic structure of oxide particles existing in 14%Cr ODS steel was performed using classical and novel transmission electron microscopy (TEM) methods. 3D dispersion, density and composition of these oxides were evaluated by atom probe tomography (APT). Three populations of particles were detected: highly dispersed 3-20 nm sized Fe,( Cr, Ti, Y and) O spinel, 50-150 nm YTiO3, and large (100-150 nm) particles identified as cubic TiC. The spinel-type particles displayed Bain and Kurdjumov-Sachs types orientation relationships (OR) with the ferritic matrix, similar to the known Fe/Fe2O3 and Fe/Fe3O4 relations. Applying electron diffraction tomography, the YTiO3 structure was attributed to the CaTiO3 (perovskite)-type and its lattice parameters were refined as a=5.701Å, b=7.690 Å and c=5.357 Å. Orientation relationship of the YTiO3 structure and Fe matrix were determined as Fe//oxide and (110)Fe//(002)oxide.
Authors : D. Mamedov, E. M. Baba, E. S. Marstein, S. Zh. Karazhanov
Affiliations : Department of Materials Science, National Research Nuclear University, 115409 Moscow, Russia, Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway; Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway; Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway; Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway.
Resume : Due to its advanced surface properties and many technologically important applications cerium dioxide (CeO2) has become under the focus of extensive research. This work presents a study of structural, electronic and optical properties of the material by first-principles calculations. In the first part, we have focused our research for bulk stoichiometric CeO2. Ce 4f orbitals are located inside the band gap. In ideal CeO2, the 4f orbitals they are not occupied with electrons. However, they are shielded from interactions with the surrounding environment by the full octet of electrons in the 5s2p6. Study of O vacancy showed that the Ce 4f orbitals become partially occupied with electrons. The impurities of yttrium, zirconium, silicon, titanium, and tin have also been considered. Formation energy and ionization energy of O vacancy and the above impurities have been calculated. The influence of the impurities on electronic structure and optical properties of CeO2 has been analyzed. It is found, that all mentioned impurity atoms reduce lattice parameters and decrease the fundamental band gap, which might be used for hydrophobicity enhancing of transparent windows.
Authors : Larysa Khomenkova 1, 2; Rada Savkina 1; Aleksey Smirnov 1; Nikita Voloshin 3; Iraida Demchenko 4
Affiliations : 1 V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41 Naukyav.,Kyiv 03028, UKRAINE 2 CIMAP CEA/CNRS/ENSICAEN/UCBN, 6 Blvd. MaréchalJuin, 14050 Caen Cedex 4, France 3 National Technical University of Ukraine ?Igor Sikorsky Kyiv Polytechnic Institute? 4 Faculty of Chemistry, University of Warsaw, KrakowskiePrzedmie?cie 26/28, 00-927 Warszawa, Poland
Resume : Transition metal oxides are the subject of active experimental and theoretical investigations last time due to a wide variety of magnetic, optical and catalytic properties. In particular, Hematite (iron oxide) is characterized by a suitable redox potential for photocatalytic water dissociation. But, one of the major limiting factors affecting the utilization of hematite as a photocatalysts include fast electron?hole recombination. This can be improved by the development of the built-in electric ?elds and charge carriers? separation by exploitation the band offset properties of Fe2O3/Cr2O3 structure. In this work, we present systematic studies of charge carrier relaxation processes of nanometric films of iron and chromium oxides (Fe2O3-x(0?x?1), Cr3-xO3-y (0?x?2; 0?y?2) as well as composite structures of the alternate layers Fe2O3-X(0?x?1)/Cr3-xO3-y(0?x?2; 0?y?2) synthesized on silicon substrates by reactive pulsed laser deposition. X-ray photoelectron spectroscopy and X-ray reflectometry analysis were used for nanometric films characterization. Investigation of the charge carriers? transport kinetics was carried out by surface photovoltage and impedance spectroscopy technique. It was found that effect of the iron and chromium oxide layers? combination results in the photovoltage enhancement of 500 times in the visible spectral region, demonstrates capacity-type impedanceand are characterized by more than one charge-carrier relaxation process. The effect of the long-term relaxation of the photovoltage was revealed also.
Authors : Nazir Jaber, Jos E. Boschker, Julian Stöver, Klaus Irmscher, Toni Markurt, Martin Albrecht, Jutta Schwarzkopf
Affiliations : Leibniz Institute für Institut für Kristallzüchtung - Forschungsverbund Berlin e.V. - Max-Born-Strasse 2, 12489 Berlin
Resume : Niobium dioxide (NbO2) exhibits a semiconductor-metal transition at 1080K. Together with its hysteretic and non-linear I-V characteristics it makes it interesting for electrical switching and memory devices. However, fundamental properties of NbO2 are only known for bulk materials, but rarely for thin films, which are necessary for technological devices. Due to the lack of NbO2 substrates, films have to be grown heteroepitaxially on lattice and thermally mismatched substrates. In this work, NbO2 thin films were heteroepitaxially grown by pulsed laser deposition on MgF2 and Al2O3 substrates. Atomic force microscopy and scanning electron microscopy images show a smooth surface morphology for not annealed films on both substrates. The layer peaks of X-ray diffraction in 2?-w scans clearly show Kiessig fringes indicating single-phase and high quality epitaxial NbO2 film growth. A post-annealing process leads not only to a modified crystalline quality of the films. But rather, during this process the films on MgF2 partially peel off due to the instability of the substrate at elevated temperatures. On the other hand the use of Al2O3 substrates has turned out to be more promising. A ?-scan on NbO2/Al2O3 shows six diffraction peaks from (400) NbO2 indicating three in-plane variants rotated by 120° from each other. Electrical conductivity measurements show a resistivity value of 2 ?/cm for the not annealed samples within increases to 500 ?/cm under the effect of the post-annealing process.
Authors : Yu.N. Bespalko1,2,*, V.A. Sadykov1,2, N.F. Eremeev1, A.V. Krasnov1,2, Yu.E. Fedorova1, P.I. Skriabin1
Affiliations : 1 ? Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia 2 ? Novosibirsk State University, Novosibirsk, Russia
Resume : Asymmetric supported membranes for hydrogen separation are state-of-the-art devices for hydrogen production from biofuels. In the current work nanocomposite permselective layers deposition technique is developed. NiCu alloy nanopowder was synthesized by modified Pecchini route followed by reduction in H2 stream in fluidized bed reactor. The tungstates and niobates of lanthanides were synthesized by mechanical activation. Nanocomposites was prepared by ultrasonic dispersion of powders in isopropanol. Catalytic permselective layers and 5 wt. % Ni + 1 wt. % Ru/ Sm0.15Pr0.15Ce0.35Zr0.3O2-? catalytic layer were deposited on NiAl foam substrate with graded porosity by vacuum slip casting. According to SEM, the surface has pores with diameter of 20-50 nm. NiAl alloy nanoparticles were additionally deposited to block these pores. Deposition technique allowed to reach required density of permselective nanocomposite layers. A high hydrogen permeation flux (up to 5 ml H2/(cm2min) and 1 ml H2/(cm2min) at 700 °C in hydrogen permeation and ethanol steam reforming tests, respectively) was demonstrated with effective activation energy ~10 kJ/mol. This is due to high mixed protonic-electronic conductivity of nanocomposites. Support by Russian Science Foundation (Project 16-13-00112) is gratefully acknowledged
Authors : Mahyar Mohammadnezhada, Gurpreet Singh Selopala,b *, Zhming M. Wang,b Barry Stansfield a, Haiguang Zhao c*, Federico Roseia,b
Affiliations : a Institut National de la Recherche Scientifique, Centre Énergie, Matériaux et Télécommunications, 1650 Boul. Lionel Boulet Varennes, Québec, J3X 1S2, Canada. b Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China. c College of Physics & State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, Qingdao 266071, P. R. China.
Resume : The long-term stability of Dye-Sensitized Solar Cells (DSSCs) is a critical issue which affects both their technical viability and future large-scale commercialization. Here, we compare the long-term stability of two devices made of (i) bare nanocrystalline TiO2 and (ii) multi-wall carbon nanotubes (MWCNTs)-TiO2 composite anode, exposed to continuous simulated sunlight, indoor and ultraviolet (UV) light irradiation. The DSSCs based on the composite anode showed approximately three times longer stability compared to the standard device. To understand the degradation mechanisms that underpin these changes in device performance, both devices were characterized using various techniques. The results indicate that the MWCNTs can act as strong conductive support and reinforcement of the TiO2 matrix in the photoanode, which prevents a reduction of electron lifetime and higher recombination rate. Based on UV stability measurements, MWCNTs are an efficient absorbing and blocking agent for UV light, thereby preventing degradation. The Raman spectra showed that dye desorption was decreased by the addition of MWCNTs.
Authors : Joanna Banas, Anita Trenczek-Zajac, Marta Radecka
Affiliations : AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Al. A. Mickiewicza 30, 30-059 Krakow, Poland
Resume : Copper oxides described by the general formula CuxO, where x = 2, 1 are a p-type multifunctional semiconductors which has drawn growing interest. Narrow band gap ranging between 1.5 and 2.4?eV allowing absorption of light from visible range, chemical stability and being friendly to the environment makes them predestine for applications in areas such as catalysis, photocatalysis and sensors. Additionally, heterostructures based on CuxO provides possibility for application as electrode applied in solar-to-chemical energy conversion. The aim of this work was to optimize deposition conditions of CuxO on the surface of titanium substrate. CuxO were deposited on Ti foil via electrochemical method. Firstly, Ti substrates were washed in ultrasonic cleaner. Then solutions for electrodeposition were prepared and each of them contained: CuSO4 (0.4 M), C3H6O3 (3 M), and appropriate amount of NaOH to determine pH values (3 ? 12). The electrodeposition was conducted in three-electrode cell ? Ti plate (working electrode), Pt wire (counter electrode), Ag/AgCl (reference electrode). Constant potential of -420 mV (pH = 9 and pH = 12) or -360 mV (pH = 12) was applied for time varied from 30 to 1800 s at temperature equal to 60°C. The following experimental methods were used: SEM, CLSM, Raman spectroscopy, and spectrophotometry. Analysis of the data revealed that changes in the deposition parameters influence not only morphology but also crystal and electronic structure of copper oxides.
Authors : Jutathip thaomonpun1, Jun Xiao Lin1, Chien Hua Huang1, Yaw Teng Tseng, Hua-Shu Hsu1*, Yen-Fa Liao2, and Zdenek Remes3
Affiliations : 1Department of Applied Physics, National Pingtung University, 4-18, Minsheng Road, Pingtung, 90044, Taiwan, 2National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu, 30013, Taiwan, 3Institute of Physics of the Czech Academy of Sciences, Cukrovarnicka 10, 16200 Praha 6, Czech Republic
Resume : ZnO nanostructures have been widely investigated in the photocatalytic ?eld, especially for the degradation of several environmental contaminants due to its high reactivity under UV light. Modification of ZnO catalyst with additional coating or doping transition metal elements could result in a decrease of the band gap and an increase of photoelectrons transfer to semiconductor surfaces under illumination of solar radiation. In addition, many researchers used magnetic nanoparticles coated on ZnO nanostructures for improving efficiency of photocatalytic properties by effectively inhibiting the charge recombination. Several kinds of magnetic particles have been reported for photocatalyst applications. Although there are reports that the integration of magnetic elements and photocatalysts could enhance the performance. But the study of manipulation the photocatalytic profound by applied magnetic field is rare. In our work the enhancement of photocatalytic activity by applied magnetic field has been achieved by using a deliberated Co2+: ZnO nanowires (NWs). Experimental degrades were measured by putting Co+2/ ZnO NWs into the Methylene blue (MB) solution at concentration is 5 mg/L with different UV light radiation time without and with magnetic field. The photocatalytic degradation of MB was observed by measuring the absorption. The photocatalytic performance of the bare ZnO NWs and Co2+: ZnO NWs is evaluated with respect to the degradation rate of the MB solution under the UV light irradiation. The percent of MB degradation increases gradually with the increase of radiation time. The photocatalytic properties of bare ZnO NWs do not show a clear difference without and with magnetic field H= 0.2 T. Interestingly, Co+2 / ZnO NWs could show 25% enhancement of photocatalytic degradation with applied magnetic field. This mechanism could be related to magnetic absorption (MA) effect. The absorption spectra of the Co+2 / ZnO NWs measured with and without a magnetic field are clearly separated after the onset of the absorption (~3.4 eV). The absorption change is positive while the applied magnetic- field and becomes significant after the onset of the absorption. However, no obvious MA effect has been observed for the ZnO NWs The induced magnetic coupling in the Co+2 / ZnO NWs enables new methods to lead to the MA effect and enhance the photocatalytic performance. Our results can provide new opportunities for the development of magnetically controlled photocatalytic activity applications. The authors would like to thank the Ministry of Science and Technology of Taiwan under Grant Nos. 107-2119-M-153 -001 and 108-2923-M-153 -002 -MY3 (Hua Shu Hsu). We are also thankful to the CSF project 19-02858J and by the Operational Programme Research, Development and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (Project No. SOLID21 -CZ.02.1.01/0.0/0.0/16_019/0000760) (Zdenek Remes).
Authors : A. Rydosz, K. Zakrzewska, E. Kusior, P. Krukowski, D. Kowalczyk, Z. Klusek
Affiliations : AGH University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, al. Mickiewicza 30, 30-059 Krakow, Poland; University of Lodz, Faculty of Physics and Applied Informatics, Department of Solid State Physics, ul. Pomorska 149/153, 90-236 Lodz, Poland
Resume : Thin films of molybdenum oxide have found a lot of applications in electronics , e.g. as gas sensitive layers. Recently, a big effort has been seen towards the use of MoO3/graphene electrodes in organic light emitting diodes . Molybdenum oxides of different stoichiometry and crystal structure can be obtained by sputtering of Mo target in the reactive Ar+O2 atmosphere . Two dimensional layered growth of MoO3 has been also reported  while in this work we demonstrate the hierarchical nanostructures synthesized by Glancing Angle Deposition, GLAD magnetron technique on amorphous silica substrates. Characterization of films was performed by X-ray diffraction XRD, X-ray reflectivity, XRR, X-ray photoelectron spectroscopy XPS, atomic force microscopy, AFM, scanning electron microscopy, SEM and optical spectrophotometry over uv and visible range of the light spectrum. This work concentrates on the mechanism of hierarchical growth of nanostructures and its potential implications on the film performance. National Science Centre, Poland projects 2016/21/B/ST5/00984 and 2016/23/B/ST7/00894 are acknowledged.  I. A. de Castro et al., Adv.Mater., 29 (2017) 1701619 (1-31)  J. Meyer et al., Sci. Rep., 4:5380  J.M. Pachlhofer et al., J.Vac.Sci. Technol. A, 35 (2017) 021504
Authors : Bart?omiej Szafraniak(1), ?ukasz Fu?nik(2), Pawe? Zydro?(2)
Affiliations : (1) AGH University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, al. A. Mickiewicza 30, 30-059 Krakow, Poland (2) AGH UST Faculty of Electrical Engineering, Automatics, Computer Science and Biomedical Engineering, al. A. Mickiewicza 30, 30-059 Krakow, Poland
Resume : The basic element of surge arresters are varistors made of zinc oxide (ZnO) with additions of other metal oxides, Bi2O3, CoO, MnO, Sb2O3 among others. A varistor working in an electrical circuit is exposed to a long-lasting DC or AC voltage load and to short-term, often repetitive, pulse repetitions. These types of interactions cause degradation of its electrical and material parameters. As a consequence, the leakage current increases during its operation and increases the power output. This can lead to destruction of the varistor due to the self-heating process. To improve the overvoltage protection of devices in electrical circuit and increase the capacity to absorb energy of overvoltages metal-oxide surge arrester are used in parallel. The paper presents an analysis of the relationship between the energy absorption capacity of parallel connected ZnO varistors with controlled energy exposure. The main problem is that a small difference in the voltage and current characteristics of the ZnO varistor surge arresters can cause uneven energy distribution between them. Acknowledgment This work has been financed by Polish National Center of Science, NCN, grant decision DEC-2016/23/B/ST7/00894.
Authors : Ø. S. Fjellvåg, K. H. Nygård, P. Vajeeston, A. O. Sjåstad
Affiliations : Centre for Materials Science and Nanotechnology - Department of Chemistry - University of Oslo
Resume : Oxyhydrides have emerged as a fascinating materials class due to the exotic combination of oxide and hydride anions, yielding interesting magnetic and electronic properties, as well as pure hydride anion conductivity.[1-3] The profound difficulties of synthesizing oxyhydrides originates from the reducing nature of the hydride anions, emphasized by the limited number of reported oxyhydrides. The LiCl salt flux method is recognized as one of few methods suitable for oxyhydride synthesis. We have investigated the synthesis of the La2?xNdxLiHO3 (0 ? x ? 2) oxyhydrides by the LiCl salt flux method and by operating the flux below its melting point we have obtained phase pure Nd2LiHO3 for the first time by this method. Our experiments show that oxyhydride synthesis by the salt flux method is delicately balanced between the thermal stability of the oxyhydride in question and the ionic mobility of the reactants. Based on this observation we suggest guidelines for oxyhydride synthesis by the salt flux method. Alternative eutectic salt fluxes are also investigated . 1. Hayward, M.A., et al., Science, 2002. 295(5561): p. 1882-1884. 2. Kobayashi, Y., et al., Nat. Mater., 2012. 11(6): p. 507-511. 3. Kobayashi, G., et al., Science, 2016. 351(6279): p. 1314-1317. 4. Kageyama, H., et al., Nature Commun., 2018. 9(1): p. 772-772. 5. Fjellvåg, Ø.S., et al, Chem. Commun., 2019
Authors : Yo Seph Lee; Nara Han; Won San Choi
Affiliations : Department of Chemical and Biological Engineering, Hanbat National University, 125 Dongseodaero, Yuseong-gu, Daejeon 305-719, Republic of Korea.
Resume : A lottery draw machine-inspired novel movable air filter (MAF) system is presented in which MAFs are vigorously moved or rotated to generate a high electric field and capture particulate matter (PM) particles. The MAF system purified 500 mL of a hazardous level of PM particles (2016 mg/m3 PM10 and 1040 mg/m3 PM2.5) at a high flow rate of 2.5 m/s with high removal efficiencies (99.7% and 98.8% for PM10 and PM2.5, respectively) in 1 min. The MAF system also had a small pressure drop of 3?6 Pa, which was approximately an order or orders of magnitude lower than previously reported values, even at a high flow rate of an order of magnitude higher than previously reported values. The MAF system exhibited excellent recyclability of up to 300 cycles with high removal efficiencies (99.7?98% and 98.8?96.2% for PM10 and PM2.5, respectively). Furthermore, the MAF system could effectively remove 500 mL of PM particles at extremely high concentrations (over 10 000 mg/m3 PM10 and over 3000 mg/m3 PM2.5) with very high efficiencies (over 99.8% and 99.6%, respectively) and a very low pressure drop (6 Pa), and these properties led to the conversion to clean ambient air (24 mg/m3 PM10 and 12 mg/m3 PM2.5) in 15 min.
Authors : Tuhin Kumar Maji, Debjani Karmakar, Samir Kumar Pal
Affiliations : Senior Research Fellow, Department of CBMS, S. N. Bose National Centre for Basic Sciences, Kolkata 700106,India; Assistant Professor, Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India; Senior Professor, Department of CBMS, S. N. Bose National Centre for Basic Sciences, Kolkata 700106,India.
Resume : Surface modification of inorganic nanoparticle using different ligand is well-known to enhance different functionality of the nanoparticles (NP), which improves tuning of relevant properties for suitable applications in the field of nanotechnology. As the NPs have a very high surface to volume ratio compared to its bulk counterpart, it has a higher possibility of having a surface defect. Surface defects of wide bandgap semiconductors play a crucial role in their properties. Defect-mediated recombination of photoinduced electron-hole pair in the semiconductors is very much well known. By modulating the defect state, it is possible to control the defect-mediated recombination. Herein, we present a facile synthesis of ZnO nanoparticle followed by surface modification using halide ions by simple precipitation method and demonstrate that proximity of various halide ions to the ZnO NP changes their electronic properties. This kind of surface modification shows very little impact on its surface morphology. On the other hand, the functionalization of halide on the surface of ZnO plays a significant role to modulate its electronic property. This change of electronic property influences their applications in photocatalytic activity or magnetism. The halide attached ZnO NP displays a large reduction of defect state emission. In the present work, we have investigated that for wide bandgap semiconducting oxides, use of anionic halide attachment like Cl- as surface defect healer proves to be more useful for photocatalytic application than bulk doping using cationic dopant like Mn. We have utilized various microscopic and spectroscopic tools (including picosecond resolved technique) to characterize the nanomaterial and the impact of different halide ions to regulate the light-induced charge separation in ZnO NP. Picosecond resolved fluorescence transients reveal a significant annihilation of the fluorescence decay, implying an electronic interaction between the NP and the attached halide ions. Upon attachment with a suitable halide ion, room temperature ferromagnetism can be achieved in the nanohybrid system. Finally, the photocatalytic activity of the halide-ZnO NP was carried out under UV light irradiation. To illustrate the impact of defect state and halide ion on the ZnO NP surface, we have carried out first principles DFT calculations using Vienna Ab-initio Simulation Package (VASP). It is found that ZnO nanoclusters with surface oxygen vacancy produce trap states within the band gap of the nanoclusters. These states effectively confine the photoinduced electrons and thus essentially reduce the photocatalytic yield with respect to pristine ZnO. However, upon proper halide attachment to the defect states, it is possible to reduce the trap state of the NP recovering the efficacy of reactive oxygen species (ROS) generation in the aqueous solution. We have shown both experimentally and theoretically, that attachment of certain halide ions onto ZnO NP affects its electronic structure and gives rise to a ferromagnetic behaviour even in the absence of magnetic ions. So, the particular halide-ZnO (namely Cl-ZnO) consolidate higher magnetic recovery, thus can be easily separated from the water after photocatalysis. In conclusion, modulation of surface defects using chloride can improve various properties of ZnO, demonstrating its utility for functionalization of ZnO NP.
Authors : Osman Urper1, Nilgun Baydogan1
Affiliations : 1)Energy Institute, Istanbul Technical University, Maslak, Istanbul, 34469, Turkey
Resume : Al-doped zinc oxide (ZnO) films were prepared by the sol-gel process and coated on the p-type substrate via dip coating technique with various of Al doping concentrations in various ambient gas conditions. In order to exhibit the change in resistivity and optic transmission of Al-doped zinc oxide and ZnO: Al/p-Si heterojunctions films depending on Al doping concentration and post-treatment techniques. Due to the increase of the temperature, films structure get denser and more crystalline shape. The lowest resistivity of 1.32x10-4 ? cm was obtained at 1.2 at.% (Al) concentration and at 700?C post-heat-treatment temperature under a vacuum ambient. All films had the preferential c-axis oriented texture according to the X-ray diffraction (XRD) results. Optical transmittance spectra of the films showed a high transmittance of over 85% in the visible region. The ohmic contacts were fabricated with Cu-grid by using a mask by cold spray on ZnO:/p-Si heterojunction. The diodes show rectifying behavior with a rectification ratio. The most conductive and rectifier heterojunction behavior were improved with Cu ohmic contact produced by cold spray technique at ZnO: Al/p-Si heterojunction (at 1.2 at.% Al doping concentration). At these characteristics, ZnO: Al/p-Si have the possibility to apply electronics application as a diode.
Authors : Agnese Stunda-Zujeva, Kristaps Rubenis, Janis Locs
Affiliations : Institute of General Chemical Engineering, Faculty of Materials Science and Applied Chemistry, Riga Technical University Paula Valdena street 3/7, Riga, LV-1048, Latvia
Resume : Materials with high chemical resistance and high electrical conductivity are necessary in various fields. TiO2 have high chemical resistance, but its electrical conductivity is very low. At strongly reducing conditions TiO2 can be reduced to the highly conductive titanium sub-oxides whose chemical resistance are comparable to TiO2. Titanium sub-oxides are commonly produced by reduction of TiO2 under H2 atmosphere at high temperatures, however, special furnace is necessary, as well as H2 is relatively expensive and dangerous. The aim of this work was to investigate the effect of process parameters on the vacuum carbothermal reduction of TiO2 with two different particle size. TiO2 with two different particle sizes (15 and 180 nm) were mixed with a carbon black (0 - 5 w%) and pressed into pellets. The obtained pellets were sintered under vacuum conditions in the range of 1100 to 1300 °C. The phase composition of the thermally treated pellets was analyzed by X-ray powder diffraction method. Phases with lower oxygen content was obtained with increasing amount of C in the samples. Samples with 5% C additive after thermal treatment mostly contained Ti3O5 and Ti4O7 phases. Ti4O7 was detected also in the samples containing 4% C. All samples in the concentration range of 1 - 5% contained at least two TinO2n-1 phases. Samples with 0.2, 0.5 and 1% C mostly consisted of TiO2. The research work has been supported by ERA-NET EU-LAC Health Project Hi-Water, No. ES RTD 2018/26 (PVS ID 3358)
Authors : Dan-dan Li, and Chun Cai
Affiliations : Nanjing University of Science & Technology 200 Xiaolingwei Nanjing, 210094, China
Resume : Increasing global awareness of the diminishing fossil energy reserves and global efforts to reduce greenhouse gas emissions have accelerated the study about utilization of renewable sources for sustainable development. Biofuels seem to be a propitious candidate for fossil fuel due to their availability, low cost, and lower greenhouse gas emissions than those of conventional petroleum-based gasoline. However, owing to the large amounts of oxygen components involved in biofuels, the calorific value of biofuels is relatively low, and biofuels are immiscible with conventional fuels and unstable over time, which limits its practical application. Therefore, biofuels must be upgraded to lower the oxygen content for future application. To study the upgrade process of lignin-derived pyrolysis oil, vanillin, a common component of lignin-derived pyrolysis oil, was selected as a model molecule. Vanillin is expected to be hydrogenated into 2-methoxy-4-methyl-phenol (MMP), which is a potential future biofuel in an ideal upgrade process. herein, we prepared a recyclable Pd catalyst supported on ZrO2 for efficient and selective hydrodeoxygenation (HDO) of vanillin under ambient pressure and neutral conditions. ZrO2 was chosen as the support because it appears to favor the activation of O-compounds on the support surface and to be essential for the hydrogen economy of the HDO reaction; besides, the amphoteric character of zirconia was reported to play a major role especially in preventing cok
Authors : Xiaofeng Yuan and Jun Luo
Affiliations : School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
Resume : The silica coated Fe3O4 was chosen as the support,and a Fe3O4@SiO2 nanoparticles supported copper imino-pyridine complex was successfully prepared by attaching copper acetate to a novel imino-pyridine ligand. The magnetic nanomaterials and organic compounds were characterized by 1H NMR, 13C NMR, XRD and IR and so on. And the structure of the product was determined. It was found that the Schiff base was successfully supported on Fe3O4@SiO2 nanoparticles by covalent bonds. The as-prepared catalyst Cu(Ⅱ)@MNP was found to be an efficient catalyst for synthesis of benzofurans. It was found that the activity is greater than or equal to the corresponding homogeneous catalyst. The magnetic nanocatalyst supported copper complex can be easily recovered by a magnetic field and reused for subsequent reactions for at least 3 times without noticeable deterioration in catalytic activity.
Authors : Dudz M. *(a), Wrobel W. (a), Malys M.(a), Borowska-Centkowska A.(a), Abrahams I.(b), Krok F.
Affiliations : (a) Faculty of Physics, Warsaw University of Technology, Koszykowa75, 00-662 Warszawa, Poland (b) Centre for Materials Research, School of Biological and Chemical Sciences, Queen Mary University of London e-mail: firstname.lastname@example.org
Resume : Lowering of operating temperature of solid oxide fuel cells (SOFCs) would reduce costs of materials for interconnectors, start-up times or degradation rates, but at the same time at lower temperatures kinetics of electrode processes slows down and higher interfacial polarization resistances are induced. In this paper composite cathode (CC), build of La0.8Sr0.2MnO3 (LSM) and Bi3Y0.9W0.1O6.15 (BiYWO) has been studied. LSM was prepared using cellulose-modified glycine-nitrate method. BiYWO was prepared using solid state reaction method, self-combustion method and co-precipitation method to obtain micrometric (micro composite) and nano (nano composite) grains, respectively. Composite cathodes (CC) were obtained by mixing BiYWO and LSM components of various grain sizes in various volume ratios, f, from f = 1 (BiYWO compound) to f = 0 (LSM compound). Symmetrical cells CC/YSZ/CC were prepared using screen printing method. The influence of the BiYWO grain size on the electrical properties will be discussed. In the case of BiYWO component prepared by solid state reaction total conductivity of composite is significantly smaller than the total conductivity of a composite with nano grain BiYWO phase. Nano grain composite show curvature characteristic for ionic component (BiYWO phase) of composite, whereas in the case if micro composite activation energy is typical for LSM compound.
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|08:55||Session VI. Nanomaterials, health and other applications. Chairs: Su Huai Wei and Smagul Karazhanov|
Authors : A.Subrahmanyam, Paul T Ramesh
Affiliations : Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India; Cardio Torasic Surgeon, Apollo Hospitals, Greams Road, Chennai 600006, India.
Resume : Photocatalysis is an established phenomenon in splitting water into hydrogen and oxygen. Several researchers have been working on the basic understanding, new and novel materials and a variety of conventional and emerging applications. The available literature is vast. Our laboratory has been working on the concept of generating oxygen in the human blood (lung assist device) using the principles of oxidative photocatalysis on the conventional materials : tin doped indium oxide (ITO) and titanium oxide (TiO2) nano thin films. The basic principle of the lung assist device is that when human blood is subjected to photocatalysis, with the water like content available in the blood (plasma) is split and oxygen is produced; this oxygen being in the immediate vicinity, the haemoglobin can pick up this oxygen. Several experiments conducted in our laboratory have clearly shown the proof of concept. We could enhance the oxygen saturation (SaO2) in the blood to about 6% (in about six hours) over the base level; this consistent result is a remarkable achievement and a firm first step towards a lung assist device. The most important boundary conditions of this application, which has been validated positively, are that no reactive species of the oxygen be produced by the photocatalytic process and the chemical nature of the human blood should not be affected even after subjecting for six (or more) hours of photocatalysis (with UV light of 254 nm). The important result of the experiment conducted so far is: 6% increase in SaO2 level in the human blood.
Authors : G. Salviati
Affiliations : IMEM-CNR, Parco Area delle Scienze 37/A, 43124 Parma, Italy
Resume : A partial overview of the research activity carried out at IMEM-CNR on Si(O)(C) and ZnO nanostructures chemically functionalized for energy and nanomedicine applications will be presented. As for energy applications, it will be demonstrated the outstanding electro-catalytic performance and stability of a hierarchical cobalt oxide (Co3O4)-functionalized vertically-aligned SiC NW array electrode for use in the oxygen evolution reaction of water splitting. The excellent electrochemical behavior, high specific capacitance and high areal power and energy of MnOx-decorated carbonized porous Si NW arrays are also shown. An asymmetric hybrid supercapacitor has been designed showing a large operational potential window and a good capacitance retention (>80% after 10000 CV cycles)). The effect of residual sulfur atoms on the optical properties of highly porous wurtzite ZnO for photocatalysis are reported. Sulfur related intra-gap states are found to be responsible for an optical emission at 2.36 eV, preferentially associated to substitutional sulfur atoms in oxygen position, in porous ZnO nanostructures. The nanoscale mapping of plasmons and excitons in ZnO tetrapods coupled with Au nanoparticles evidences that the Au plasmon resonance is localized at the Au/vacuum interface, rather than presenting an isotropic distribution around the nanoparticle. This result paves the way for innovative devices like e.g. hybrid solar cells. As for nanomedicine applications, it will be reported that by exciting directly the fluorescence of CeF3 NPs in CeF3-ZnO nanocomposite by UV radiation, ZnO is photo-activated in cascade, producing reactive oxygen species that are known to induce necrosis in cancer cells. Our composite nanostructure is stable in aqueous media with excellent optical coupling between the two components and presents good cell viability, with very low intrinsic cytotoxicity in dark. It will be also reported that SIC-NWs can support cardiac bioelectric propagation over distance in-vitro via an intrinsic physiological gap junction conductance. Further, in vivo injection SIC-NWs in an ischemic area favours the elimination of ventricular ectopic activities and re-instate bioelectric conduction, recovering the time interval between the beginning of the ventricular depolarization and the end of the ventricular repolarization as well as the depolarization complex of the ventricles prolongations. Finally the use of SiC/SiO2 NWs for the reconversion of medical X-rays to light to activate an in-situ deep solid tumor treatment will be presented. It will be shown how the in vivo injection of SiC/SiO2 NWs into a lung cancer improves of about 40% the efficacy of radiotherapy without NWs. The concurrent use of SiC/SiO2 NWs with an innovative monoclonal antibody- pthalocianine conjugate for pancreatic and liver cancer treatments under soft X-ray irradiation will be also illustrated.
Authors : Viktoriia Fedorenko, Daina Damberga, Igor Iatsunskyi, Emerson Coy, Rados?aw Mrówczy?ski, Roman Viter
Affiliations : Institute of Atomic Physics and Spectroscopy, University of Latvia, Jelgavas 3, Riga, Latvia, LV-1050; NanoBioMedical Centre, Adam Mickiewicz University, 85 Umultowska str., 61-614, Poznan, Poland
Resume : Development of polydopamine (PDA) based composite nanomaterials is an actual subject. PDA is a biocompatible synthetic polymer, which has strong affinity to a wide range of surfaces due to the existence of multiple functional groups (such as indole, catechol, quinone, and indolic/catecholic ?-system), which can be attached to organic and inorganic materials. Among a number of different inorganic functional materials, ZnO is well known and interesting due to its structure (different architectures), electrochemical (high isoelectric point (IEP) (pH~9.1)) and optical properties (high exciton binding energy and high PL at room temperature). The combination of ZnO with PDA layers could improve optical, electronic and sensitive properties of ZnO/PDA towards target molecules. In the present work, 1D ZnO nanowires (ZnONWs) were coated with PDA film via chemical bath deposition. PDA is derived from self-polymerization of dopamine in alkaline aqueous solutions (in our study, TRIS buffer solution was utilized). Structure, optical and electronic properties of ZnONWs/PDA core/shell nanostructures were analyzed by TEM, XRD, Raman and FTIR spectroscopy, photoluminescence measurements, and diffuse reflectance spectroscopy. The TEM measurements confirmed the conformal coating of PDA with different layer thicknesses. To confirm the PDA formation EELS was performed. Correlation between structural and optical properties of the prepared nanostructures was shown. The obtained results were discussed.
Authors : Cristiana Figus1*, Mariangela Oggianu2, Claudia Caltagirone2 , Vito Lippolis2 , Maria Laura Mercuri2 , Francesco Quochi1
Affiliations : 1Dipartimento di Fisica? Universita? degli Studi di Cagliari, S.P. Monserrato-Sestu Km 0,700, I-09042 Monserrato, Cagliari, Italy 2 Dipartimento di Scienze Chimiche e Geologiche, Universita? degli Studi di Cagliari, S.P. Monserrato-Sestu Km 0,700, I-09042 Monserrato, Cagliari, Italy
Resume : Heavy metals contamination is becoming one of the most serious problems due their toxicity for the environment and the human health, even at low concentrations. In this regard, considerable eﬀorts have been devoted to the development of a simple and inexpensive method for the selective and sensitive detection of heavy metal ions. In the present study, an optimized and finely controlled three-step approach was used to develop a fluorescent amine-modified silica-based platform for selective sensing of metal ions in aqueous solution. Silica films of controlled thickness and wettability were prepared by an optimized combination of sol-gel method and spin-coating technique. Tetraethoxysilane (TEOS) was used as silica precursor on silicon substrates. Subsequently, a monolayer of aminosilanes (APTES) was grafted on the silica surface. Finally, ﬂuorescein isothiocyanate (FITC) was covalently bonded on the surface of the amine-modified silica platform. These materials were systematically characterized by water contact angle, diffuse reflectance, atomic force microscopy (AFM), and photoluminescence spectroscopy. The stability of the silica-based functionalized platforms in water was assessed prior to sensing experiments. Photoluminescence titration experiments successfully demonstrated that this system can be used as for selective sensing of metal ions in aqueous solution.
|10:55||Session VII. Solar Cells. Chairs: Larysa Khomenkova and Eugen Stamate|
Authors : Aleksandra B. Djurisic,1 Fangzhou Liu,1 Ho Won Tam,1 Tik Lun Leung,1 Jingyang Lin,1,2, Wei Chen, 1,2 Alan Man Ching Ng, 2 Zhubing He,2
Affiliations : 1. The University of Hong Kong 2. Southern University of Science and Technology (SUSTech)
Resume : Organometallic halide perovskite solar cells (PSCs) have been attracting extensive research interests due to their excellent photovoltaic performance and potential for low cost and scale-up fabrication. In a common PSC architecture, electron and hole transport layers play an important role in achieving high power conversion efficiency besides the perovskite layer. Metal oxide semiconductors are among the most promising candidates for charge carrier transport layers due to their suitable energy alignment for charge extraction and blocking, considerable chemical stability and spectral transparency, as well as low cost and easy fabrication. Further improving the electrical properties of intrinsic metal oxides and metal-oxide/perovskite interfaces are critical to boost the overall efficiency of the PSCs. In this work we demonstrate low-temperature solution processible metal oxide transport layers for both conventional and inverted planar PSCs, including NiOx as the hole transport layer and SnO as the electron transport layer. The metal oxide layers are further optimized by doping with inorganic (Cu, Sb) or organic molecule (F6TCNNQ) dopants to enhance the charge extraction while suppress the interfacial recombination loss. Various characterization results indicate that the carrier concentration and carrier mobility of the metal oxide transport layers can be effectively increased with reduced energy level offset, which implement the achievement of highly efficient and stable PSCs.
Authors : Antonio Vázquez-López (1), Smagul Karazhanov (2), Halvard Haug (2) David Maestre(1), Julio Ramírez-Castellanos(3), Erik Marstein (2), Ana Cremades(1)
Affiliations : (1) Department of Materials Physics, Faculty of Physics, Complutense University of Madrid, 28040 Madrid, Spain; (2) Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Oslo, Norway; (3) Department of Inorganic Chemistry I, Faculty of Chemistry, Complutense University of Madrid, 28040 Madrid, Spain
Resume : Because of the high electrical conductivity and transparency to visible light, PEDOT:PSS has found applications in a number of photovoltaic devices. Incorporation of nanosized inorganic semiconductors to the polymer is suggested to enhance performance. In this work, anatase TiO2 nanoparticles have been synthesized and incorporated into PEDOT:PSS . Optical and electrical properties of TiO2 can be modified by controlling the size of the nanoparticles and by doping. Firstly anatase TiO2 nanoparticles were synthesized via hydrolysis using Ti(OBu)4 as precursor. Two different dopants, Ni and Li, in a variable cationic concentration were introduced adding NiCl2 6H2O or LiCl, respectively. Large amount of nanoparticles has been obtained with high crystallinity and homogeneity in sizes around 10 nm, as confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). Changes in the TiO2 vibrational modes and luminescence were observed as a function of the doping, as shown by Raman spectroscopy and Photoluminescence X-ray photoemission spectroscopy (XPS) shows changes on the O 1s core level due to dopant inclusion. Hybrid composites have been prepared via spin coating of PEDOT:PSS funcionalized with a variable amount of the nanoparticles, among other wettability and conduction enhancers (DMSO, EG, Triton X-100) over n-type Si substrates. Homogeneous microsized dispersion has been obtained, with layer thickness around 120 nm. Lifetime values in the range of 200-400 us were measured by PL-QSSPC.  M García-Tecedor, S. Z. Karazhanov, G. C. Vásquez, H. Haug, D. Maestre, A. Cremades, M. Taeño, J. Ramírez-Castellanos, J.M. González-Calbet, J. Piqueras, C.C. You, E. S. Marstein, Nanotechnology, 29, 035401 (2018)
Authors : Mriganka Singh, Hong-Cheu Lin, Chih-Wei Chu, and Gang Li
Affiliations : Mriganka Singh and Hong-Cheu Lin: Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan, Republic of China; Chih-Wei Chu: Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan; Gang Li: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
Resume : Metal oxide carrier transporting layers have been investigated widely in organic/inorganic lead halide perovskite solar cells (PSCs). Tin oxide (SnO2) is a promising alternative to the titanium dioxide commonly used in the electron transporting layer (ETL), due to its tunable carrier concentration, high electron mobility, amenability to low-temperature annealing processing, and large energy bandgap. In this study, a facile method was developed for the preparation of a room-temperature-processed SnO2 electron transporting material that provided a high-quality ETL, leading to PSCs displaying high power conversion efficiency (PCE) and stability. A novel physical ball milling method was first employed to prepare chemically pure ground SnO2 nanoparticles (G-SnO2), and a sol?gel process was used to prepare a compact SnO2 (C-SnO2) layer. The effects of various types of ETLs (C-SnO2, G-SnO2, composite G-SnO2/C-SnO2) on the performance of the PSCs are investigated. The composite SnO2 nanostructure formed a robust ETL having efficient carrier transport properties; accordingly, carrier recombination between the ETL and mixed perovskite was inhibited. PSCs incorporating C-SnO2, G-SnO2, and G-SnO2/C-SnO2 as ETLs provided PCEs of 16.46, 17.92, and 21.09%, respectively. In addition to their high efficiency, the devices featuring the composite SnO2 (G-SnO2/C-SnO2) nanostructures possessed excellent long-term stability?they maintained 89% (with encapsulation) and 83% (without encapsulation) of their initial PCEs after 105 days (>2500 h) and 60 days (>1400 h), respectively, when stored under dry ambient air (20 ± 5 RH %).
Authors : Giacomo Rossi (1), Daniele Catone (2), Alberto Piccioni (1), Nicola Patelli (1), Alessandra Paladini (3), Alessandra Molinari (4), Stefano Caramori (4), Lucia Amidani (5), Patrick O? Keeffe (3), Federico Boscherini (1), Luca Pasquini (1)
Affiliations : (1) - Department of Physics and Astronomy, Alma Mater Studiorum Università di Bologna, V. C. Berti-Pichat 6/2, 40127 Bologna, Italy (2) - CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit), Area della Ricerca di Roma Tor Vergata, Via del Fosso del Cavaliere 100, Rome, Italy (3) - CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit), Area della Ricerca di Roma 1, Monterotondo Scalo, Italy (4) ? Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy (5) ESRF ? The European Synchrotron, CS40220, 38043 Grenoble, France
Resume : The incorporation of dopants in metal-oxide semiconductor photocatalysts can be used to red-shift the optical absorption edge and to enhance the photocatalytic activity under solar irradiation. However, the dopant-induced energy levels and the spectral dependence of photoactivity are not yet fully understood. We tackle this problem using a combination of femtosecond-resolved transient absorption spectroscopy in the UV-visible range  and high energy resolution x-ray absorption spectroscopy under differential illumination . This last approach, recently developed within our group exploiting the unique features of high-brilliance synchrotron sources, provides the chemical sensitivity necessary to identify element-specific photoexcitation paths. The focus of our study are vanadium-doped TiO2 nanoparticles (V-TiO2 NPs) prepared by gas-phase condensation , that exhibit both photocatalytic activity for -NO2 reduction and photoelectrochemical water splitting in the visible spectral range, where undoped TiO2 NPs are completely inactive. We explain the material?s behavior, relevant to energy and environment-related applications, by determining the position of the dopant-induced intra-gap level and by studying the photoelectron excitation and trapping dynamics with elemental sensitivity.  G. Rossi et al, Appl. Catal. B ? Environmental 237, p. 603 (2018)  G. Rossi et al, Phys. Rev. B 96, p. 045303 (2017)  G. Rossi et al, J. Phys. Chem. C 120, p. 7457 (2016)
Authors : Hyelim Cho, Jae-yeoun Kim, Seran Park, Dae-Hong Ko
Affiliations : Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
Resume : Nowadays, the implementation of flexible devices and the light weight are on the rise. We attempted to implement solar cells that can be used in flexible devices by using carbon paper as a substrate. In addition, ZnO/Ag was combined as a back reflector to improve the performance. However, when carbon is used as a substrate, it can diffuse into the Ag layer in the subsequent p-i-n process range of 200 to 400 ° C. To prevent this, we added a metal oxide layer, SiO2 or SnOx, as a carbon diffusion barrier between the carbon substrate and the back reflector. Further, we confirmed the optical characteristics and the effect of preventing carbon diffusion with and without the oxide layer. Experimental results showed that the back reflector bonded to the metal oxide layer showed better performance, and the SnOx bonding showed the best performance. First, the surface of the carbon paper was cleaned, and each film was deposited using an RF magnetron sputter. The thickness of the back reflector of Ag was 350 nm and that of Zn was 100 nm. For the carbon diffusion barrier, an oxide layer of 100 nm was first deposited, followed by the back reflector layer. The optical properties were examined using ultraviolet-visible spectroscopy, and cross sections were confirmed through transmission electron microscopy. The diffusion characteristics of carbon were evaluated using time of flight-secondary ion mass spectrometry after 200?400 ? heat treatment process in a dry furnace.
|13:55||Session VIII. Synthesis and characterization. Chairs: Andrej Kuznetsov and Jose Montero|
Authors : A.Calka, and D.Wexler
Affiliations : University of Wollongong, Faculty of Engineering and Information Sciences,School of Mechanical, Materials , Mechatronics and Bioengineering, Australia,
Resume : Many functional materials are traditionally synthesized by slow reaction processes that are energy and time consuming. In the present world there is strong demand on development of modern materials and materials processing methods that could offer rapid reaction rates, energy efficiency and be environmentally safe. Complex metal oxide ceramics have found wide applications in energy storage capacitors, electromechanical transducers, piezoelectric, and ferroelectric devices. The conventional method to prepare complex metal oxide ceramics is ceramic-powder-based processing, i.e., through solid-state reaction at high temperatures. This process has several disadvantages, such as high-temperature reaction, limited degree of chemical homogeneity, and low sintering ability. Therefore, during past years, several chemical-based processing routes, including freeze-drying, spray-pyrolysis, sol? gel, spray-drying, and pyrolysis of complex compounds, have been developed to prepare powders with more homogeneous composition, improved reactivity, and sintering ability at low temperatures. Recently, non-conventional processing methods such as mechanical alloying and mechano-chemical approaches have been used to create reactions between species. However in this method the reaction kinetics is very slow and processing time long. The objective of the present study is to investigate the application of an Electro-Mechano-Chemical (EMC) technique to synthesize various metal- oxide ceramics, in particular formation of nano-phases and characterize the structural, physical, and optical properties. By using EMC, high purity single phase multi-element oxides can be formed in as little as 0.1% of the processing time required in conventional solid-state techniques. An even more important feature of EMC is that the crystallite size of the synthesized compound is able to be reduced to nanometer size, by careful selection of electrical (voltage, current, total power) and mechanical (vibration frequency and amplitude) experimental parameters. We use EMC for (i) synthesis of metal oxides from elemental powders by oxidation in oxygen plasma and for (ii) synthesis of single phase multi element oxides from pre-mixed oxides as starting materials. This presentation provides an overview of recent development of EMC method and it?s application in rapid synthesis of Perovskite ABO3 type oxide ceramics such as BaHfO3, BaTiO3, MnTiO3, PbZrO3, other complex metal oxides and metal oxyhydrides and others. References 1. A.Calka and D.Wexler, Nature, 419,(2002)147-151
Authors : Maryam Mohammad-Hosseinpour, Amin Yourdkhani, Reza Poursalehi
Affiliations : Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran, 14115
Resume : Here, we report room temperature growth of the continuous layers consisting plate-like WO3.2H2O on a large area of indium doped tin oxide (ITO) coated glass substrates with excellent adhesion by using liquid phase deposition (LPD) technique. Electrochromic properties of the continuous WO3.2H2O 350 nm thick films were evaluated by cyclic voltammetry and chronoamperometry. During cyclic voltammetry experiments at negative currents reduction process occurs via intercalation of equal numbers of protons and electrons into the film working electrode. The films change their color from colorless to dark blue. Conversely, in positive currents oxidation process occurs and the color of the films changes back to its original color via deintercalation of protons and electrons back to the electrolyte. The bleaching and coloration time were determined based on chronoamperometry experiments about 3.2 and 14.1 s. These results indicate that coloration is a slow process whereas bleaching is kinetically a fast process. The cycling performance of the film was evaluated with a two electrode system using a square wave with 1 V amplitude and 30 s period time. Visually, the film constantly was transformed to colored and bleached states within about 900 cycles which afterwards the film was detached from the substrate.
Authors : Ece Kurt, Duygu Kalkan, Esra Zayim
Affiliations : Faculty of Science and Letters, Physics Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
Resume : Electrochromic (EC) materials being among chromogenic materials have the area of usage increasing day by day. The most common areas of usage of the EC materials are glasses, sensors and display panels. With the applied potential differences, little ions such as Li+ and H+ inserted to the film and material changes its optical state. Electrochemical impedance spectroscopy (EIS) is one of the best technique to determine the electronic properties of thin films. Explication of EIS data gives useful information about electrolyte resistance, charge transfer resistance, capacitance of the sample. It is also very common to determine an equivalent circuit model to reach information about the density of states and bandgap electronic structure of thin films. In this study, organic/inorganic EC materials such as WO3 and PANI were coated on ITO with several technics such as electrodeposition, chemical bath deposition and spin coating. EC behaviors of these films were measured with the 3-electrode system and cyclic voltammetry (CV), chronoamperometry (CA) analysis was done in order to monitor its ion exchange. Electronic properties of films were obtained with the EIS measurements. Band gaps were calculated and compared with the literature and experimentally obtained.
Authors : Salih Veziroglu, Majid Hussain, Marie Ullrich, Lynn Schwaeke, Jaeho Hwang, Thomas Strunskus, Franz Faupel, Oral Cenk Aktas
Affiliations : Chair for Multicomponent Materials, Institute for Materials Science, Christian Albrechts University of Kiel, 24143 Kiel, Germany
Resume : Noble metal (Au, Ag, and Pt, etc.) micro and nanostructures (M-Ns) have being received exceptional attention during the last decades, due to their unique structural, electronic and catalytic properties. Especially, the incorporation of these M-Ns with wide-bandgap semiconductor metal oxides such as titanium oxide (TiO2) has been shown to enhance their (photo)catalytic activity in the visible and ultraviolet (UV) irradiation due to plasmonic and non-plasmonic enhancement. (Photo)catalytic properties of hybrid structures can be finely tuned by controlling the shape and size of Au M-Ns.[1,2] In the literature, there are various studies about the synthesis of M-Ns well-defined size and morphology. However, it is still a challenge to achieve good adhesion between M-Ns and metal oxide surface. Therefore, some approaches (seed-mediated growth, etc.) have been published to enhance the adhesion of Au M-Ns on metal oxide by using some binder molecules (thiols and silanes, etc.). Mostly organic molecules are used for binding Au M-Ns with a solid substrate. However, these may decrease the surface conductivity and affect the catalytic activity of the Au M-Ns. Similarly, electrodeposition methods can also be used to prepare Au M-Ns on the solid substrates. But the electrodeposition process works only on the conductive substrate such as indium tin oxide (ITO). Therefore, there is a need to prepare stable Au M-Ns on metal oxide thin films without using any organic molecules (binders) or a conductive electrode. Here, we demonstrate a novel photocatalytic deposition approach for preparing Au M-Ns on metal oxide surface by UV illumination with strong chemical adhesion. This method allows the controlling the geometry, size, and distribution of such Au M-Ns on metal oxide thin film by simply changing the deposition solution, photocatalytic activity of metal oxide, UV illumination intensity and time.  S. Veziroglu, M. Z. Ghori, M. Kamp, L. Kienle, H. G. Rubahn, T. Strunskus, J. Fiutowski, J. Adam, F. Faupel, and O. C. Aktas, Adv. Mater. Interfaces, 2018, 5, 1800465.  S. Veziroglu, M. Z. Ghori, A.-L. Obermann, K. Röder, O. Polonskyi, T. Strunskus, F. Faupel and O. C. Aktas, Phys. status solidi, 2019, 1800898.
Authors : S. Abad1, A. Prados1, A. Muñoz-Noval1, G. C. Vásquez2, L. Vines2, R. Ranchal1
Affiliations : 1Dpt. Física de Materiales, Fac. CC. Físicas, Universidad Complutense de Madrid, Madrid 28040, Spain; Centre for Materials Science and Nanotechnology, University of Oslo, N-0318 Oslo, Norway.
Resume : GaFeO3 (GFO) oxides are of great interest due to their magnetoelectric properties that can be exploited in multiferroic devices [1-3]. Pulsed laser deposition can be used to deposit high quality films, but it is difficult to be extrapolated to industrial facilities. We have explored electrodeposition and thermal oxidation as alternative growth processes. Electrodeposited layers show evidences of partial oxidation for Ga, whereas Fe seems to keep its metallic state. The electrolyte composition enables to achieve flat films, whereas the Fe/Ga ratio can be tuned by the applied growth potential. For thermal oxidation, we have monitored the evolution of sputtered uncapped Fe70Ga30 thin films with temperature. The treatment in oxygen atmosphere promotes the formation of Ga-rich aggregates at 500 °C. At 600 °C there are evidences of Ga oxidation but not for Fe, and at 700 °C Ga evaporates . A better strategy for the oxidation seems the use of Mo capping layers to reduce the formation of Ga aggregates. Annealing at lower temperatures, between 200 °C and 400 °C, also seems to decrease the surface damage. A further optimization of the thermal oxidation process is the use of appropriate substrates for the FeGa layers that are eventually oxidized.  J. Atanelov, P. Mohn, Phys. Rev. B 92 (2015) 104408.  S. Mukherjee et al., Phys. Rev. Lett. 111 (2013) 087601.  H. Niu et al., J. Am. Chem. Soc. 139 (2017) 1520.  P. Alvarez-Alvarez et al., J. Alloys Compnd. 713 (2017) 229.
|15:55||Session IX. Oxide nanomaterials. Chairs: Martynas Lelis and Alexandra Djurisic|
Authors : Andrej Kuznetsov
Affiliations : Department of Physics and Centre for Material science and Nanotechnology, University of Oslo, Pb 1048 Blindern, 0316 Oslo, Norway
Resume : Gallium oxide (Ga2O3) is an interesting wide bandgap material having either insulating or semiconducting properties depending on the concentration and type of the impurities as well as intrinsic defects. The interest to Ga2O3 is because of its exceptional fundamental properties, specifically promising for power electronics, and of potential use in a range of other applications, e.g. in solar blind photodetectors, scintillators for medical diagnostics, transparent and passivating layers in solar cells, detectors tolerating high radiation/temperature, etc. For power electronics, among other materials, Ga2O3 possess most superior properties (humbled by diamond only), as such ranking it increasingly high among other ?energy? materials. One of the issues slowing down the use of Ga2O3 is the lack of fundamental understanding and difficulties in controlling electrically active point defects and defect complexes. Indeed, starting from ?simplest? point defects, due to the low symmetry of typically used monoclinic ?-Ga2O3, there are two different configurations of Ga in the unit cell (tetragonal and octagonal, GaT and GaO, respectively) and three different environments in the O sub-lattice in ?-Ga2O3. Such complexity results in equally many different vacancy configurations and sites for extrinsic impurities to reside, provoking a number of electronic states in the bandgap. Further, taking into consideration potential extrinsic impurities and corresponding defect complexes, the result is a plethora of potential localized electronic states. Some initial understanding has been accounted recently, not least by provoking defect formation induced by irradiation. In this presentation, upon discussing the perspectives and challenges, the results of our recent investigations of electrically active levels in ?-Ga2O3 will be highlighted  and set in the context of the present understanding . Our approach is to use electron and ion irradiation for controllable introduction of the intrinsic defects into the material. In its turn, the methodological strength is in using a combination of the deep level transient spectroscopy (DLTS), secondary ion mass spectrometry (SIMS), and hybrid functional calculations for guiding the experimental work.  M.E. Ingebrigtsen, et al. APL, 112 42104(2018); M.E. Ingebrigtsen, et al., APL Mater., 112, 42104 (2019); M.E. Ingebrigtsen, et al. JAP, in press (2019).  Irmscher, K., Z. Galazka, M. Pietsch, R. Uecker, R. Fornari. J. Appl. Phys., 110 63720(2011); Zhang, Z., E. Farzana, A.R. Arehart, S.A. Ringel. Appl. Phys. Lett., 108 52105(2016); Gao, H., S. Muralidharan, N. Pronin, M.R. Karim, S.M. White, T. Asel, G. Foster, S. Krishnamoorthy, S. Rajan, L.R. Cao, M. Higashiwaki, H.v. Wenckstern, M. Grundmann, H. Zhao, D.C. Look, L.J. Brillson. Appl. Phys. Lett., 112 242102(2018).
Authors : Martin Eickhoff
Affiliations : Institute of Solid State Physics, University of Bremen, Bremen, Germany
Resume : We report on the growth of metastable (Mg,Zn)O oxide alloys and Ga2O3 polymorphs by plasma-assisted molecular beam epitaxy (PAMBE). The achievable maximum concentration of Mg in polar (Mg,Zn)O thin films is limited by the onset of phase separation into wurtzite and rock salt structure. Depending on the growth method, the substrate material and the applied growth conditions the reported incorporation limit varies between 4% and around 40%. The highest concentrations in MBE-grown layers were achieved for non-equilibrium growth conditions at low temperatures around 270°C. Thermal annealing of thin films with Mg concentrations of 28% and 38% grown on c-plane sapphire results in a transition from a pure wurtzite phase to the coexistence of wurtzite and rock salt phases. Transmission electron microscopy revealed a vertical equilibration of the (Mg,Zn)O film into a complex heterostructure, consisting of alternating rock salt and wurtzite layers. In the second part we show that the growth window of beta-Ga2O3, usually limited by the formation of volatile gallium sub-oxide in the Ga-rich regime, is expanded by the presence of tin during the growth process. By application of various analytic techniques we demonstrate that the presence of tin results in the formation of phase-pure metastable epsilon-Ga2O3 when Ga-rich growth conditions are applied. A growth model based on the oxidation of gallium sub-oxide using tin as a catalyst is suggested and the incorporation characteristics of tin are assessed. We will show that the catalytic growth process presents a promising technology platform for the synthesis of epsilon-Ga2O3 nanostructures.
Authors : M. Alonso-Orts (1), E. Nogales (1), A. M. Sánchez (2) and B. Méndez (1)
Affiliations : (1) Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040-Madrid, Spain (2) Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom
Resume : Gallium oxide is attracting a lot of interest due to both its optical and electrical properties. Its wide band gap (4.9 eV) provides applications in UV-blue photodetectors. On the other hand, the huge breakdown field (8 MV/cm) makes Ga2O3 a competitive alternative to diamond or SiC materials for power device applications. Most of the reported work is based on thin films. In this work, we report the synthesis of undoped and doped ?-Ga2O3 nanowires of high crystalline quality by thermal evaporation methods. The approach allows for shape engineering by suitable selection of impurities. Ge and Sn are used as n-type dopants and their incorporation in the monoclinic phase is discussed. In addition, the formation of branched, crossing wires and particle decorated NWs is explored. Finally, we report the luminescence and light confinement properties in Cr doped nanowires.
Authors : A. Bailly, S. Grenier, M. M. Villamayor, M. Gaudin, A. Y. Ramos, P. Bouvier, L. Magaud, L. Laversenne
Affiliations : Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
Resume : Bulk vanadium dioxide (VO2) is an archetypal strongly-correlated electron material exhibiting a first-order metal-insulator transition (MIT) at T(MIT)~68°C. This transition is characterized by a drastic resistivity change and a structural transformation from an insulating monoclinic phase at room temperature (RT) to a metallic tetragonal rutile-like phase above T(MIT). This makes VO2 an interesting candidate for integration in energy-related devices, such as passive radiators or thermochromic windows. The fact that VO2 is usually in the form of films opens the way for easily tuning its MIT characteristics directly via the synthesis conditions. We hereby present a structural and spectroscopic study of a VO2 film grown on Al2O3(0001) by reactive sputtering. We combined High-Resolution X-Ray Diffraction and Raman spectroscopy to address the crystallographic phases present during the MIT. We established two structural models to account for the possible epitaxial relationships and demonstrate that their respective signatures in reciprocal space allow to easily differentiate them by diffraction. At RT, the phase is similar to the monoclinic M1 bulk phase. Above 66°C, it transforms into a M2-like polymorph. Upon further temperature increase, this latter partially turns into the rutile R-like polymorph. The coexistence of M2 and R phases is attested well above the transition temperature, questioning the importance of interfacial strain in the M2 phase stability.
Authors : F. del Prado1, H. F. Andersen2, M. Taeño1, J. Ramirez-Castellanos3, D. Maestre1, JP. Maehlen2, S. Karazahanov4 A. Cremades1
Affiliations : 1 Facultad de C. Físicas, Universidad Complutense de Madrid, Madrid, Spain; 2 Department for Battery Technologies, Institute for Energy Technology, 2027 Kjeller, Norway; 3 Facultad de C. Químicas, Universidad Complutense de Madrid, Madrid, Spain; 4 Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway
Resume : The facile synthesis of graphene oxide (GO), which also possesses a band gap, can overcome some limitations of graphene in technological applications. On the other hand, current research mainstreams dealing with advanced luminescent materials are related to the achievement of white light emission using carbon derivatives . Different synthesis routes were used to prepare GO composites with Li doped SnO2 nanoparticles  for evaluation of its performance for applications as anodes in Li-ion batteries (LIBs) and as luminescent materials. Galvanostatic charge and discharge cycling in CR2032-type half-cells showed that SnO2-based anodes have a high capacity in the charge/discharge process up to 100 cycles, while an intermediate capacity for the GO/SnO2 composite was observed. The capacity remains stable after the 200th cycle, showing that the materials can be used as a promising alternative anode material for LIBs. The composites exhibit photoluminescence related to functional groups and surface defects in GO. As a general trend the composites with a higher amount of oxygen functional groups exhibit lower PL intensity, whereas the presence of Li as well as formation of SnO and reduced GO induces higher PL signal. Moreover, the intensity of the luminescence from the composites is larger than from pure GO, while maintaining a nearly white emission. 1. Félix del Prado, María Taeño, David Maestre, Julio Ramírez-Castellanos, José María González-Calbet and Ana Cremades, J. Phys. and Chem. of Solids 129, 133?139 (2019) 2. Félix del Prado Hurtado, Ana Cremades, David Maestre, Julio Ramirez-Castellanos, José M González-Calbet and Javier Piqueras, Journal of Material Chemistry A 6, 6299-6308 (2018)
Authors : Borisyuk P. V., Lebedinskii Yu. Yu., Vasilyev O.S.
Affiliations : National Research Nuclear University MEPhI (Moscow Engineering Physics Institute); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow Institute of Physics and Technology (State University); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute)
Resume : Modern photovoltaic energy converters based on the use of wide absorption spectrum, including near infrared range is currently of increased interest. We present a study of an original nanomaterial, namely, a thin multilayer nanostructured film consisting of metal oxide Ni or Ta nanoparticles (2-15 nm in diameter) with the spatial ordering of nanoclusters by size as a potential photovoltaic material. The system is an ensemble of densely packed metal nanoclusters with a gradient size distribution of nanoparticles deposited on the surface of silicon oxide. A key feature of the system is that the presence of the size dependence of the Fermi energy leads to the spatial redistribution of the charge in the system as a whole. That means that the average size of metal nanoparticles in the conducting system of nanoparticles in contact with each other monotonically changes in the selected direction, the potential difference is observed in the same direction. The appearance of a photoelectron in this system leads to the flow of the electron in the direction of the potential gradient. Since nanoclusters are metal, this provides the ability to detect photons of different wavelengths and provides a wide spectrum of radiation absorption. Nanocluster layers are formed using magnerton sputtering method with built-in mass filtration of nanoclusters that provide layer-by-layer formation of monodisperse layers made of different nanocluster sizes. The obtained preliminary results on the formation and study of the chemical, electron, and optical properties of the obtained multilayer nanocluster films are discussed.
Authors : Yinghong Wu (1, 2), Jingkui Qu (1), Walid A. Daoud (2), Tao Qi (1)
Affiliations : (1) Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China. (2) School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong.
Resume : With the rapid growth of wearable electronics, flexible and high-performance power sources has attracted increasing attention. Among various energy harvester, triboelectric nanogenerator (TENG) is highly promising owing to its light weight, easy fabrication, broad material selection, and high conversion efficiency. However, many traditional TENG are based on hard materials, which decreases the effective contact between the triboelectric pair and the output performance. Although more and more flexible TENG have recently been developed, they still show confined deformability and are hardly used in shape-adaptable devices. Herein, by employing graphene oxide (GO) dispersion as the liquid electrode while PDMS as the electrification layer, novel liquid single-electrode TENG (LS-TENG) with simple structure and high deformability, is firstly developed. The output performanceof this device is remarkably improved by adding a small amount of GO dispersion, where its open-circuit voltage and short-circuit current density are 123.1 V and 18.61 mA?m-2, respectively. This is much better than the reported LS-TENG based on NaCl solution and liquid metal. Moreover, Its maximum power density achieves 4.95 W?m-2 at a contact frequency of 3 Hz, which is higher than that of reported GO solid single-electrode TENG (3.13 W?m-2, 5 Hz). When palm taps the device with an electrode size of 2×2 cm2, 87 green LEDs in series can be lit up. Tests, such as robustness, durability, and repeatability, all indicate its high stability and potential in practical application. Minute body movement inputs on skin and clothes, indicate its high sensitivity and potential use in highly-flexible and highly-deformable wearable electronics.
Authors : Brahim Aïssa1,*, Amir A. Abdallah1, Maulid M. Kivambe1, Yahya Zakaria1, Ayman Samara1, Jean Cattin2, Jan Haschke2, Mathieu Boccard2 and Christophe Ballif2
Affiliations : 1 Qatar Environment and Energy Research Institute, Hamad bin Khalifa University, Qatar Foundation, P.O. Box 34110, Doha, Qatar 2 Photovoltaics and Thin-Film Electronics Laboratory (PV-lab), Institute of Microengineering, Ecole Polytechnique Fédérale de Lausanne, Rue de la Maladière 71B, CH-2002 Neuchâtel, Switzerland
Resume : Silicon heterojunction (SHJ) solar cells that combine advanced thin-film hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) technologies are a promising architecture that already demonstrated records-high values of open-circuit voltages that successfully enabled to high power conversion efficiencies even at the industrial production level . For instance, SHJ solar cells feature high open-circuit voltages, generally well above 730 mV, world-record fill factor (FF) of 84.9% and power conversion efficiency of 26.7% as demonstrated in 2017 by Kaneka Corp . Moreover, SHJ layers are typically deposited below 200 °C, which lowers considerably the thermal budget in production of the solar cell and at the same time allows for high throughput production machinery . Due to the low conductivity of a-Si:H, transparent conductive oxide (TCO) needs to be used as a front contact layer on top of a-Si:H in order to collect photogenerated currents. However, TCOs must feature simultaneously high electrical conductivity, low contact resistance with the adjacent layers, and an appropriate refractive index for maximal light in-coupling into the device. In this work, we report on the optoelectronic properties of ITO layers deposited by DC sputtering, using different oxygen to total flow ratios [r(O2) = O2/Ar, ranging from 1% to 8%], for silicon heterojunction (SHJ) solar cell application. The depth profiling of the various elements throughout the thicknesses and interfaces of the ITOs and thin films forming the SHJ device was determined by time-of-flight secondary ion mass spectrometry. Finally, the photovoltaic performance of the fabricated SHJ cells was evaluated with respect to the r(O2) into the ITO layers. Lower r(O2) was found to yield the best PV performance which is attributed to lower parasitic resistive losses.  M. Zeman, D. Zhang, ?Heterojunction Silicon Based Solar Cells. Physics and Technology of Amorphous-Crystalline Heterostructure Silicon Solar Cells,? ed: Springer, (2011).  K. Yoshikawa, H. Kawasaki, W. Yoshida, T. Irie, K. Konishi, K. Nakano, T. Uto, D. Adachi, M. Kanematsu, H. Uzu, K. Yamamoto, ?Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion effciency over 26%,? Nat. Energy 2, 17032 (2017).
Authors : 1. Junghyo Nah 2. Min Hyung Lee
Affiliations : 1. Dept. of Electrical Engineering, Chungnam National University, Daejeon, South Korea 2. Dept. of Applied Chemistry, Kyung Hee University, Yongin, South Korea
Resume : One of effective approaches to obtain high performance water splitting device is to form desirable band bending at the interface between the charge generation material and electrolyte. For this purpose, ferroelectrics materials can be promising candidate, attributed to the induced polarization by applying high electric field. In this way, the modulated band bending along with desired direction overcomes the intrinsic property of anode or cathode in water splitting. Herein, we selected semiconducting and ferroelectric zinc oxide (ZnO) nanomaterials by doping with lithium and vanadium. The modulated spontaneous polarization in doped ZnO as photoanode was systematically investigated, varying the valence band bends upward or downward at the electrolyte interface. Consequently, the solar-tohydrogen (STH) efficiency using positively-polarized photoanode improved up to up to ~200 %, thanks to the favorable band bending for the generated hole transfer to electrolyte in comparison to the negatively-polarized one. The approach introduced using ferroelectric ZnO is simple, effective, and suitable way to design the high performance photoelectrochemical device. For the future work, also, the ferroelectric ZnO in core-shell design can be easily adopted by combining desirable anode material.
Authors : Ozcan Koysuren, Hafize Nagehan Koysuren
Affiliations : Department of Energy Engineering, Ankara University, Ankara, 06830, TURKEY; Department of Environmental Engineering, Ahi Evran University, Kirsehir, 40100, TURKEY
Resume : It was aimed to study the photocatalytic activity of polyaniline (Pani)/iron doped titanium dioxide (Fe-TiO2) composites for the degradation of methylene blue under UV light irradiation. For this purpose, TiO2 nanoparticles were doped with iron ions (Fe) and the doped photocatalyst nanoparticles were introduced into Pani by using an in situ polymerization technique. Pani composites, including 10, 20 and 30 wt.% Fe-TiO2 and undoped TiO2, were prepared via this technique. FTIR, XRD, SEM, EDX and UV?Vis spectroscopies were utilized to characterize the photocatalyst and the composites. According to SEM images, both Fe-TiO2 and TiO2 nanoparticles in aggregated form were distributed homogeneously within Pani matrix. UV-Vis spectroscopy revealed that the band gap of TiO2 widened to 3.18 eV with iron doping and Pani extended the absorption of TiO2 nanoparticles to the visible light region. When compared with undoped TiO2 and its composites, Fe-TiO2 and Pani/Fe-TiO2 exhibited improved photocatalytic activity under UVC light irradiation. Doping the photocatalyst with iron ions might improve the photocatalytic activity through hindering the recombination of the photoinduced charge carriers on TiO2 nanoparticles. The highest dye removal value (28%) was obtained with Pani composite, containing 30 wt.% Fe-TiO2 nanoparticles. In addition, the discoloration rate of the model dye, methylene blue, for the composite sample was 0.0025 min-1.
Authors : Kobasa I.M. 1, Sema O.V. 1, Vorobets M.M. 1, Vorobets G.I. 2
Affiliations : 1 Chemical Analysis, Expertise and Safety of Food Products Department, Institute of Biology, Chemistry and Bioresources, Yuriy Fedkovych Chernivtsi National University, 58012 Chernivtsi, Ukraine, email@example.com, firstname.lastname@example.org, email@example.com 2 Computer Systems and Networks Department, Institute of Physical-Technical and Computer Sciences, Yuriy Fedkovych Chernivtsi National University, 58012 Chernivtsi, Ukraine, firstname.lastname@example.org
Resume : The method of sensitization of semiconductor materials, in particular TiO2, polymethine dyes, is a promising approach to the creation of high-performance photocatalytic systems with an extended range of photosensitivity. In this work, the anionic symmetrical polymethine dye 9-ezenyl-2,4,5,7-tetranitro- [2- (2,4,5,7-tetranitro-9H fluorene-9-ezenyl) ethylidene] triethylammonium 9-H- Fluorene (D), which contains three conjugate chromophores, is used to sensitize titanium dioxide. The analysis of the spectral, electrochemical and energy characteristics of the investigated dye shows the possibility of using it as an effective titanium dioxide sensitizer. The method of cyclic voltammetry has been used to determine the oxidation and renewal potentials of the dye and to calculate their redox potentials in the excited state. It is found that they are sufficient for sensitization by transferring electrons to the conduction band TiO2. New light-sensitive heterostructures D/TiO2 (HS) were created. Their photocatalytic activity in the oxidation reaction of iodide ions is determined depending on the irradiation conditions and the concentration of the dye-sensitizer. The energy diagrams of possible electronic processes caused by the action of light absorbed by both a semiconductor and a dye-sensitizer are investigated. An explanation of the found laws is offered.
Authors : M.Taeño1, D. Maestre1, J. Ramírez-Castellanos2, J.M. González Calbet2, A. Cremades1
Affiliations : 1Dpto. Física de Materiales. Fac. CC. Físicas, Universidad Complutense de Madrid, Spain 2Dpto. Química Inorgánica I, Fac. CC. Químicas, Universidad Complutense de Madrid, Spain
Resume : NiO, with cubic structure, belongs to the family of p-type wide band gap semiconductor oxides, demonstrating potential applicability in gas sensors, electrochemical supercapacitors or catalysis, among others . Using an appropriate synthesis method can lead to optimize most of these applications by reducing the size and selecting proper chemical composition. In this work, NiO nanoparticles undoped and doped with Sn content between 3 and 30% atomic, have been synthesized by a soft chemistry route based on hydrothermal process, using Ni (NO3)2·9H2O and SnCl2·2H2O as starting materials. The incorporation of Sn can modify the NiO optoelectronic response. In addition, formation of NiO/SnO2 p-n heterojunctions can be also promoted, with applications in photocatalysis or solar cells. The as-grown nanoparticles, with rock-salt structure, show good crystallinity in all cases, and homogeneity in size with dimensions between 7-15 nm. An increase in Sn content leads to a decrease in the particle size and finally to the stabilization of SnO2 phase with rutile structure, as confirmed by X-ray diffraction (XRD). The characterization of the nanoparticles was performed by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), Raman Spectroscopy, Cathodoluminescence (CL), Photoluminescence (PL) and X-Ray Photoelectron Spectroscopy (XPS) at the Elettra synchrotron. CL and PL results show two main emissions centered at 2.3 and 2.8 eV, and a weak emission around 2 eV. XPS measurements show changes in the Sn4+/Sn2+ ratio as a function of Sn content in the nanoparticles, which also involves variable Ni3+/Ni2+ ratio.  M. Wang, J.Han, Y.Hu, R. Guo, Y.Yin. App.Mat & Interf. 8, 29511-29521 (2016)
Authors : T. Shinagawa, M. Chigane, M. Izaki
Affiliations : Osaka Research Institute of Industrial Science and Technology; Toyohashi University of Technology
Resume : Solar cells are devices using renewable energy to solve global environmental problems and limited natural resources problems in recent years, and further cost reduction and higher photovoltaic performance are required for their widespread use. Oxide semiconductor-based thin-film solar cells represented by n-ZnO/p-Cu2O heterojunction type solar cells have been attracting attention as low-cost and environmentally friendly solar cells that can be manufactured by aqueous-solution processes and general purpose metals, such as Zn and Cu, as raw materials.[1-4] The aqueous-solution process that does not use a vacuum process or high temperature heat treatments enables the use of plastic substrates. The fabrication of flexible and lightweight oxide solar cells can also be expected to find new applications by taking advantage of its superior characteristics. In this study, ZnO/Cu2O heterojunction has been prepared on a conductive oxide-coated flexible plastic substrate using electrochemical deposition in aqueous solution. We adopted Al-doped ZnO as a conductive oxide and polyethylene naphthalate as a flexible substrate, and investigated the effect of ZnO/Cu2O deposition conditions on the photovoltaic performance. By controlling the deposition rate and the film thickness, photovoltaic performance comparable to that using conventional glass substrates was achieved.  M. Izaki, T. Shinagawa, K. T. Mizuno, Y. Ida, M. Inaba, A. Tasaka, J. Phys. D: Appl. Phys. 2007, 40, 3326.  A. T. Marin, D. Muñoz-Rojas, D. C. Iza, T. Gershon, K. P. Musselman, J. L. MacManus-Driscoll, Adv. Funct. Mater. 2013, 23, 3413.  T. Shinagawa, K. Shibata, O. Shimomura, M. Chigane, R. Nomura, M. Izaki, J. Mater. Chem. C 2014, 2, 2908.
Authors : J. Cardin(1), L. Dumont(1), C. Labbé(1), P.-M. Anglade(1),C. Frilay(1), S.C. Wu(2), I.-S. Yu(2), X. Portier(1), P. Marie(1), F. Gourbilleau(1)
Affiliations : (1) CIMAP, Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, 14000 Caen, France (2) Department of Materials Science and Engineering, National Dong Hwa University, Hualien, Taiwan
Resume : One of the most promising approaches to increase the Si Solar Cell (SC) efficiency is its combination with frequency conversion layers, which spectrally redistributes irradiance to obtain a larger spectral overlapping with the Si-SC absorptivity. Therefore, conversion efficiency increases at the expense of the thermalization of photogenerated carriers. Down Conversion (DC) and Down Shifting (DS) processes are achieved by means of absorption and emission Rare Earth (RE) ions, such as Tb3+-Yb3+ for DC and Tb3+ for the DS. Major disadvantages of RE ions are their low excitability and their host matrix low chemical compatibility with Si SC. We present in this paper the study of DC (DS) layers, consisting in a Si-based matrix doped with Tb3+-Yb3+ (Tb3+) ions fabricated by a sputtering approach and structurally and optically characterized. The role of RE concentration on cooperative energy transfer (CET) in rare earth ions solid solution was investigated by growing mixed RE thin film and multilayer thin film constituted of an alternation of SiNx:Yb3+ and SiNx:Tb3+ sublayers of few nanometers thick. The resulting DC (DS) conversion efficiency was investigated experimentally and by means of a Monte-Carlo model allowing to explain the role of RE ions interdistances on the CET mechanism and consequently on the efficiency of the conversion. Finally, we successfully integrated our SiNx Tb3+-Yb3+ DC layers on a silicon based SC and determined a relative efficiency improvement up to 1.34%.
Authors : Marina García1, Julio Ramírez-Castellanos 2, Emilio Nogales1, Bianchi Méndez1, Chang Chuan You3, Smagul Karazhanov3, E. S. Marstein3.
Affiliations : 1Department of Physics of Materials, Faculty of Physical Sciences, University Complutense Madrid, Spain. 2Department of Inorganic Chemistry, Faculty of Chemical Sciences, University Complutense Madrid, Spain. 3Department for Solar Energy, Institute for Energy Technology (IFE), PO BOX 40, 202, Kjeller, Norway.
Resume : In recent years the study of hybrid solar cells has increased and one of the research lines includes the incorporation of new material to enhance their properties1. Nanocrystalline transparent conductive oxides (TCO) within PEDOT:PSS are being studied for this kind of solar cells in order to improve their stability and electrical behaviour, as well as obtain enhanced tunability of their optical and electrical properties. In this work, we study the characteristics of PEDOT:PSS with embedded ?-Ga2O3 or ?-Ga2O3 nanoparticles2. Structural, morphological, optical and electrical characterization has been carried out with X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), photoluminescence excitation (PLE), cathodoluminescence (CL) and Raman spectroscopy. The effect that the ?- and ?- nanocrystals phases induce on the performance of the hybrid system will be discussed. 1. Jäckle S, Mattiza M, Liebhaber M, et al. Junction formation and current transport mechanisms in hybrid n-Si/PEDOT:PSS solar cells. Sci Rep. 2015;5:1-12. doi:10.1038/srep13008 2. García-Tecedor M, Karazhanov SZ, Vásquez GC, et al. Silicon surface passivation by PEDOT: PSS functionalized by SnO2 and TiO2 nanoparticles. Nanotechnology. 2018;29(3). doi:10.1088/1361-6528/aa9c9e
Authors : Mohammadreza Khodabakhsh(1,2), Ugur Unal(1,3), Nader Parvin(2)
Affiliations : (1) Department of Materials Science and Engineering, Graduate School of Science and Engineering, Koç University, Istanbul,Turkey. (2) Faculty of Mining and Materials Engineering, Amirkabir University of Technology, Hafez Ave, Tehran, Iran. (3) Koç University Surface Science and Technology Center (KUYTAM), Istanbul, Turkey.
Resume : In recent years, application of heterogeneous photocatalysts, especially environmentally friendly oxide semiconductors have proven to be a highly efficient and economical approach for toxic organic pollutants degradation. In this regard, many efforts have been made to modify bandgap structure and extend the range of light absorption through metal and nonmetal doping. However, Doping can reduce photocatalytic performance of semiconductor nanoparticles by introducing defects and trapping centers which increase recombination rate of photogenerated electrons and holes. Instead of the traditional idea of changing the bandgap, we have tried to enhance photocatalytic properties of Aurivillius phase layered structure Bi2SrTa2O9 through ?Exfoliation/Restacking? process. This new approach not only can increase the specific surface area of the photocatalyst, but also shorten the charge transport pathways which leads to less chance for electron-hole recombination. AFM measurements have shown that Individual nanosheets are similar in thickness (approximately 2 nm) but different in lateral dimension ranging between 200 nm to as large as one micron. Comparing data obtained from BET analysis reveals that specific surface area for restacked nanosheets is almost 13 times higher than the original layered perovskite. Besides, negatively charged surface of the nanosheets enhances adsorption of cationic dyes such as RhB on the surface of catalyst. Comparing photocatalytic activity of original layered perovskite (Bi2SrTa2O9) with that of restacked [SrTa2O7]2- nanosheets under UV light irradiation has shown significant reduction in reaction time for photocatalytic degradation of Rhodamine B from 180 min to 20 min.
Authors : Sang Hyun Ji, Ji Sun Yun
Affiliations : Energy& Environmental Division, Korea Institute of Ceramic Engineering and Technology
Resume : Lead-free piezoelectric nanofiber sheets were prepared by the electrospinning method, and then the piezoelectric nanofibers in the shell parts were twined around a conductive thread (the inner electrode layer) in the core parts. The outer electrode layers were made by braiding the core-shell piezoelectric nanofiber yarns with conductive thread, and the core-shell piezoelectric nanofiber yarns with external electrodes were then directly stitched onto the fabric. The stitching patterns of the core-shell piezoelectric yarns were optimized as long as possible with a stitching interval of 0.15 cm inside an effective area. Energy could be harvested from various garments (a glove, a guard, and a shoe insole) directly stitched with the core-shell piezoelectric yarns according to various bending and pressing body movements.
Authors : Hamid Reza Zafarani, J. Ruud van Ommen
Affiliations : Delft university of technology
Resume : Using the sun?s energy to generate hydrogen from water is probably the cleanest and most sustainable source of fuel that we can envisage. Unfortunately, catalysts that do this are currently whether too expensive or low in efficiency.In this research we employed Atomic Layer Deposition (ALD) technique to deposit Metal oxide nanocluster on TiO2 nanoparticle surface. The results show improved photocatalytic activity in the visible range and increased hydrogen evolution efficiency.
Authors : Kurelchuk Uliana N., Borisyuk Petr V., Vasiliev Oleg S.
Affiliations : National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) 115409, Russian Federation, Moscow, Kashirskoe shosse, 31.
Resume : Study of thermoelectric properties of model materials made from the d-metals nanoclusters is presented. Semiclassical thermoelectric transport coefficients was obtained from the non-empirical band structure calculated by DFT. Transport coefficients calculated in bulk limits showed coincidence with the reference ones and obeyed the Lorentz ratio for bulk metals. Up to 50 times increasing of the Seebeck coefficient was obtained numerically for nanoclustered model materials with respect to the bulk one. It stays in agreement with the experimentally observed trends of nanoclusters properties. Relationship of structural, electronic and thermoelectric properties of nanoclusters and structures, formed from it, is discussed in order to developing of highly efficient thermoelectric materials.
Authors : Antonio Vázquez-López (1), David Maestre (1) ,Julio Ramírez-Castellanos (2), Neslihan Yuca(3), Ana Cremades(1)
Affiliations : (1) Department of Materials Physics, Faculty of Physics, Complutense University of Madrid, 28040 Madrid, Spain; (2) Department of Inorganic Chemistry I, Faculty of Chemistry, Complutense University of Madrid, 28040 Madrid, Spain; (3) Enwair Enerji Teknolojileri A.? (Enwair), ITU Bee Technopolis, 34467, Sar?yer/?stanbul, Turkey;
Resume : Wide-band semiconductors as SnO2 have demonstrated potential applications  in diverse fields ranging from catalysis, optoelectronic devices or energy storaging as batteries. During the last years increasing attention has been focused on the use of SnO2 nanoparticles in ion-Lithium batteries (LiB), for which controlled morfology and size of the nanaoparticles as well as appropriate doping is necessary. In this work, rutile SnO2 nanoparticles have been synthesized by means of a hydrolysis method using SnCl2 2H2O as precursor. Ni or Li doping have been achieved adding a controlled ratio of NiCl2 6H2O or LiCl, respectively. With this method we have obtained rutile SnO2 nanoparticles with high crystallinity and sizes around 20 nm, as measured with X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The cationic concentration of the dopants, ranging from 0.1 to 3.6 at. %, has been measured with energy dispersive X-ray spectroscopy (EDX) and plasma Spectroscopy (ICP-OES). Raman spectroscopy measurements show variations in the vibrational modes as a function of the dopant. Also photoluminescence (PL) has been studied using a He-Cd (325 nm) laser as excitation source. Changes in oxygen vacancies related bands have been observed as a function of the dopant. X-ray photoemission spectroscopy (XPS) acquired at the Elettra synchrotron shows variable Ni3 /Ni2 as a function of the doping. Furthermore, undoped and Li or Ni doped SnO2 nanoparticles were used as anodes in Li ion cells showing an initial capacitance around 700 mAh/g and good stability over 100 cycles.  F. del Prado, A. Cremades, D. Maestre, J. Ramírez-Castellanos, J.M. González-Calbet and J. Piqueras, J. Mater. Chem. A, 2018, 6, 6299-6308
Authors : A. Yaseen (1), A. Vázquez-López (2), D. Maestre (2), J. Ramírez-Castellanos (3), E. S. Marstein (1), S. Z. Karazhanov (1), A. Cremades (2)
Affiliations : (1) Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Oslo, Norway (2) Departamento de Física de Materiales, Facultad de CC. Físicas, Universidad Complutense de Madrid, 28040, Madrid, Spain (3) Departamento de Química Inorgánica, Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040, Madrid, Spain
Resume : Hybrid solar cells combining organic and inorganic materials have recently become of great interest not only in photovoltaic applications , but also as sensors and in microelectronic devices. However, despite the promising efficiencies reported for hybrid composites so far, several aspects still require to be further addressed to overcome some limitations of these compounds and improve their applicability. In this work hybrid composites formed by a conductive polymer PEDOT:PSS functionalized with SnO nanoparticles (1 wt. %) have been investigated. A preliminary study of bare PEDOT:PSS and romarchite SnO nanoparticles synthesized by hydrolysis were firstly carried out. The composites were deposited on n-Si or glass substrates by spin-coating, leading to layers with a thickness around 120 nm and an average surface roughness of 3.5 +- 0.5 nm, as measured by AFM. Electrical and photoluminescence measurements were also performed in these samples. The influence of a piranha pre-treatment on the Si surface has been evaluated. Besides, the stability of the polymer under irradiation has been analyzed by Raman spectroscopy using a UV laser as excitation source. Changes in the region 1200-1500 cm-1 characteristic from the PEDOT:PSS were observed after continuous irradiation. Finally, the composites including SnO nanoparticles were used for n-Si surface passivation. Lifetime values around 350 us were measured by PL-QSSPC, which confirms good passivation behaviour even without pre-treatment of the Si substrate.  M García-Tecedor, S. Z. Karazhanov, G. C. Vásquez, H. Haug, D. Maestre, A. Cremades, M. Taeño, J. Ramírez-Castellanos, J.M. González-Calbet, J. Piqueras, C.C. You, E. S. Marstein, Nanotechnology 29, 035401 (2018)
Authors : Solbi Shin?, Jae-Yeon Lee?, Won-Suk Kim* and Kyungkon Kim*
Affiliations : Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Korea.
Resume : A novel TiO2 nanoparticles (TNP-Cat) synthesized by chelating with catechol derivatives have been demonstrated. These synthesized TNP-Cats are highly dispersive in organic solvents and form dense film with small roughness. Various analysis including X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) have been conducted to investigate physical, chemical and electrical properties of TNP-Cats. Analysis results showed that chelating the catechol derivatives on the TiO2 alter the energy level of the TiO2 nanoparticles. These TNP-Cats were utilized an electron transporting layer of organic photovoltaic (OPV) devices. In this presentation, characteristics of TNP-Cats and solar cell performances of OPV devices utilizing Cat-TPNs will be discussed.
Authors : D. Moldarev 1,2, M. Taeño 3, D. Maestre 3, A. Cremades 3, S. Zh. Karazhanov 1, E. Marstein 1
Affiliations : 1 Department for Solar Energy, Institute for Energy Technology (IFE), 2027 Kjeller, Norway; 2 Department of Materials Science, National Research Nuclear University MEPhI, 115409 Moscow, Russia; 3 Departamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
Resume : The hybrid organic-silicon solar cell concept has started to attract attention in the scientific community. This is due to an attractive combination of potentially simple device fabrication and competitive efficiency compared to other silicon-based solar cell architectures. It has recently been demonstrated that spin-coated poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (hereafter PEDOT:PSS) on silicon wafer is a promising material due to its good optical and electrical properties. However, degradation caused by atmospheric exposure and relatively poor passivation properties limit implementation of PEDOT:PSS?silicon devices. Functionalization of PEDOT:PSS by inorganic nanoparticles is a possible solutions, as was shown for TiO2 and SnO2 nanoparticles. In this work we present our study of the optical and passivation properties of PEDOT:PSS, as well as the effect of its functionalization by NiO nanoparticles on these properties and material durability. The influence of nanoparticles on the electrical properties of the heterojunction PEDOT:PSS/n-Si will be also demonstrated.
Authors : D. Beketova, M. Motola, H. Sopha, V. ?i?mancova, F. Dvo?ak, L. Hromadko, M. Stoica, J. M. Macak
Affiliations : D. Beketova1; M. Motola1; H. Sopha1,2; V. ?i?mancova1, F. Dvo?ak1, L. Hromadko1,2; M. Stoica3; J. M. Macak1,2 1. Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 530 02, Pardubice, Czech Republic 2. Central European Institute of Technology, Brno University of Technology, Purkynova 123, 612 00 Brno, Czech Republic 3. Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
Resume : In recent years, many basic principles have been developed to improve and optimize TiO2-based materials as photocatalysts. Herein, we demonstrated new solvothermal oleate approach for the fabrication of TiO2 1D anodized nanotubes decorated with Fe3O4 nanoparticles. The as-prepared samples revealed enhanced photocatalytical activity in photodegradation of methylene blue under visible light irradiation. According to recent studies [1, 2], double-walled nanotubes, containing secondary layer of electrolyte deposition, display lower degradation rate in comparison to single-walled samples. Therefore, single-walled TiO2 nanotube composites were shown to have the highest rate constants, namely, 0.41??? 10-2 and 0.48 10-2 min-1, compared to non-decorated nanotubes. Increase in concentration of the Fe3O4 nanoparticles in 3 times leads to growth of particle size from 20 to 30 nm and formation of bunches and beads. For these samples, the photocatalytic activity reduced due to unavailable surface area. Based on these data, we can conclude, that the resulted TiO2 composite materials produced with a low amount of Fe3O4 nanoparticles could perform as promising magnetically-guidable, low-cost, environmentally-friendly photocatalysts . 1. Mirabolghasemi H., Liu N., Lee K., Schmuki P. Chem. Commun. 2013, 49, 2067?2069. 2. Motola M., Sopha H., Krbal M., Hromadko L., Olmrova Zmrhalova Z., Plesch G., Macak J.M. Electrochem. Commun. 2018, 97, 1-5 3. D. Beketova et al., Ms in preparation.
Authors : Lukas Bastakys1; Fariza Kalyk1; Liutauras Marcinauskas1; Jurgita ?yvien?1; Brigita Abakevi?ien?1
Affiliations : 1 - Department of Physics, Kaunas University of Technology, Studentu str. 50, LT-51368 Kaunas, Lithuania
Resume : Thin film CeO2-based electrolytes are usually fabricated by physical and chemical vapour deposition techniques, such as electron beam evaporation, pulsed laser ablation, magnetron sputtering, spray pyrolysis, metal-organic vapour deposition, and others. It is considered that relatively low deposition rates and high equipment cost are characteristic of the vacuum deposition methods in comparison with traditional methods of ceramic layers? formation (screen printing, electrophoretic deposition, tape casting, and etc.). Despite this, vacuum methods have a number of unique advantages, where very thin and fully dense layers may be fabricated at low temperatures. In this work, gadolinia-doped ceria (GDC, Gd0,1Ce0,9O1,95) multilayer sandwich system (4 ? 12 layers) were deposited on Si (111) substrate by direct current reactive magnetron sputtering in O2/Ar gas mixture. Deposited GDC thin films were annealed at 700 °C for 1 h in air. After the deposition process GDC thin films had a columnar structure, but the dense structures were formed after the annealing process. The structural, morphological, and phase compositional properties of sputtered GDC thin films were investigated using X-Ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Phase composition results revealed the presence of fluorite microstructure. GDC thin film thickness was ~700-900 nm was evaluated from SEM results. The diffusion of Ce and Gd in multi-layered gadolinia-ceria systems was observed by Rutherford Backscattering spectroscopy (RBS).
Authors : Ece Kurt, Duygu Kalkan, Esra Zayim
Affiliations : Istanbul Technical University, Department of Physics Engineering, Maslak, Istanbul
Resume : Electrochromic (EC) materials being among chromogenic materials have the area of usage increasing day by day. The most common areas of usage of the EC materials are glasses, sensors and display panels. With the applied potential differences, little ions such as Li+ and H+ inserted to the film and material changes its optical state. Electrochemical impedance spectroscopy (EIS) is one of the best technique to determine the electronic properties of thin films. Explication of EIS data gives useful information about electrolyte resistance, charge transfer resistance, capacitance of the sample. It is also very common to determine an equivalent circuit model to reach information about the density of states and band gap electronic structure of thin films. In this study, organic/inorganic EC materials such as WO3 and PANI were coated on ITO with several techniques such as electrodeposition, chemical bath deposition and spin coating. EC behaviors of these films were measured with the 3-electrode system and cyclic voltammetry (CV), chronoamperometry (CA) analysis was done in order to monitor its ion exchange. Electronic properties of films were obtained with the EIS measurements. Band gaps were calculated and compared with the literature and experimentally obtained.
Authors : Dilek Evecan, Esra Zayim
Affiliations : Faculty of Science and Letters, Physics Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
Resume : More recently, there has been a growing interest on electrochromic devices (ECD) that is able to control the throughput of visible light into buildings that provides the control of energy efficiency by using a small electrical voltage. A great deal of previous research focused on tungsten oxide that is the most studied inorganic electrochromic material due to its better coloration efficiency. In the recent years, extensive research has been carried out on not only the inorganic chromogenic materials, but also the organic ones. This study provides a novel approach to quantifying fabrication and characterization of the all-solid-state electrochromic (EC) devices made up with different electrolytes (Nafion, gel electrolyte LiClO4-propylen carbonate- poly (LiClO4-PC-PMMA), etc) are reported in this study. Herein, organic and inorganic hybrid systems are considered to be produced. These devices consist of electrolyte, inorganic working (tungsten oxide) and organic counter electrode thin films deposited on Indium-tin oxide substrates.
Authors : Eugen Stamate, Kion Norrman, Poul Norby
Affiliations : Technical University of Denmark
Resume : Resource and cost limitations for indium, requires a timely development of new thin-film transparent conducting oxides, with aluminum doped zinc oxide (AZO) as one strong candidate. Targeted use include large-area and big-market applications, such as soar cells, touch panels, organic-LED and smart windows. Despite of intensive research, the AZO thin-film growth mechanism by magnetron sputtering is not understood, fact reflected by good optoelectronic properties limited to certain regions over the substrate surface. So far, it was demonstrated that, under certain deposition conditions, the AZO resistivity varies with more than two orders of magnitude over a substrate span below of 10 mm while the transmittance remains above 85%. This work reports on spatially resolved properties of AZO thin films by TOF-SIMS, XPS and XRD in correlation with spatially resolved plasma parameters by probes (electrical and thermal) and optical emission spectroscopy. A 2 mm in diameter gold probe is scanned at the level of substrate surface below a 2 inch sputtering cathode (RF or DC operation) to record plasma density. An optical fiber can also measure the probe surface temperature by fluorescence decay between pulses of violet radiation. The same scanning system is used to record optical emission spectra, revealing the spatial distribution of aluminum, zinc and oxygen. This work was supported by the Innovation Fund Denmark through research project no 6151-0011B: SmartCoating.
Authors : Zengjun Chen, Tatjana Dedova, Ilona Oja Acik, Malle Krunks
Affiliations : Zengjun Chen; Tatjana Dedova; Ilona Oja Acik; Malle Krunks. Laboratory of Thin Film Chemical Technologies Department of Materials and Environmental Technology Tallinn University of Technology Ehitajate tee 5, EE-19086 Tallinn, Estonia E-mail: Malle.Krunks@taltech.ee
Resume : Nickel (II) oxide (NiO) thin films were successfully synthesized via simple pneumatic spray pyrolysis method using nickel acetate precursor. The effects of deposition temperature, volume of spray solution and precursor concentration on structural, optical and photocatalytic properties of the NiO films were investigated. XRD, UV-Vis spectroscopy, water contact angle measurement and photodegradation of methyl orange (MO) under UV irradiation were used to characterize deposited films. XRD patterns reveal that independent of the technological parameters all the films are of cubic NiO. The average crystallite size changes from 2 to 8 nm varying the substrate temperature (Ts) from 260 to 400 °C. The bandgap values (direct transitions) were 3.8 eV for the films grown at Ts of 260 °C and at around 3.3 eV if grown at higher temperatures. The deposition temperature and film thickness were found to be the key parameters that influence the samples wettability and MO degradation efficiency. The water contact angles (CA) are 10° and 30°, MO degradation efficiency values are 80%/3h and 15%/3 h for the films deposited at 300 °C and 400 °C, respectively. Increasing the volume of spray solution from 25 mL to 150 mL decreases the CA values from 25 to 8? and increases degradation efficiency of MO from 32% to 80% for the films deposited at 300 °C.
Authors : D. Mamedov, C. C. You, S. Zh. Karazhanov, E. S. Marstein
Affiliations : Department of Materials Science, National Research Nuclear University, 115409 Moscow, Russia, Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway; Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway; Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway; Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway;
Resume : Hole-conducting poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is a materials receiving increasing interest for use in photovoltaic devices. In this work, we present the results of study of the degradation of the optical and electrical properties of pure PEDOT:PSS pure and PEDOT:PSS doped with Si-nanoparticles. The PEDOT:PSS has been deposited on top of Si wafers by spin coating. We found that incorporation of Si nanoparticles into PEDOT:PSS enhances the surface passivation of the surface of Si wafer by increasing the carrier lifetime measured by PL QSS-PC method from about 320 µs to 420 µs for the injection level at 2*10^15 cm^-3. The sheet resistance of PEDOT:PSS has also been increased. Analysis showed that incorporation of the Si nanoparticles does not change noticeable neither Si surface passivation nor kinetics of degradation of lifetime. We report also current-voltage dependence for Si/PEDOT:PSS.
Authors : Hao Li1, Jing Wang1, Lizhi Zhang2
Affiliations : 1. Laboratory of Advanced Analytical Technologies, Empa, Dübendorf, Switzerland 2. Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Applied & Environmental Chemistry, College of Chemistry, Central China Normal University, China
Resume : It is of a great challenge to seek for semiconductor photocatalysts with prominent reactivity to remove kinetically inert dilute NO without NO2 emission. Complete visible light NO oxidation mediated by O2 is achieved over a defect-engineered BiOCl with high selectivity. Well-designed one-electron trapped oxygen vacancies (VO´) on the prototypical (001) surface of BiOCl favors the possible formation of geometric-favorable superoxide radicals (?O2-) in a side-on bridging mode under ambient condition, which thermodynamically suppresses the terminal end-on ?O2--associated NO2 emission in case of higher temperatures, and thus selectively oxidize NO to nitrate. Differently, two-electron-trapped oxygen vacancy (VO?) on BiOCl(010) surface, a prototypical F center, accomplishes NO oxidation through a two-electron charging (VO? + O2 ? VO?-O22-) and subsequent one-electron decharging process (VO?-O22- + NO ? VO-NO3- + e-). The back-donated electron is re-trapped by oxygen vacancy to breed a new single-electron-trapped VO´, simultaneously triggering a second round of NO oxidation (VO´-O2 + NO ? VO-NO3-). These findings can help us to understand the intriguing surface chemistry of photocatalytic NO oxidation and design highly efficient NOx removal systems.
Authors : 1. T. Tom,J.M. Asensi, J. Andreu, J. Bertomeu 2. E. Ros, C. Voz, P. Ortega
Affiliations : 1. Departament de Física Aplicada, Universitat de Barcelona. email: email@example.com 2.Departament d'Enginyeria Electrònica, Universitat Politècnica de Catalunya. email: firstname.lastname@example.org
Resume : Abstract The reactive rf magnetron sputtering using H2:Ar plasma on ZnO targets leads to highly transparent and conducting films [1,2]. In this work, aluminum-doped zinc oxide (ZnO:Al) films have been deposited by rf magnetron sputtering using H2:Ar mixtures at various pressures and temperatures. Significant reduction in the resistivity and increase in the optical properties of the films is observed due to the effect of hydrogen incorporation, increase in pressure and as well as temperature. The aim is to optimize ZnO:Al layers to replace the indium tin oxide (ITO) layers, which is the most widely used transparent conductive oxide (TCO) in the market but is expensive due to indium. Analysis of ZnO:Al films with different doping concentrations of hydrogen, pressure, and temperature will be presented. Electrical characterization by four-point probe measurements and optical transmission spectroscopy are used to assess the suitability of the ZnO:Al structures as TCO, by using the Haacke figure of merit (FOM). Heterojunction silicon solar cells also will be fabricated using ZnO:Al replacing the ITO to study the increase in efficiency and open circuit voltage(Voc) of the cells. References: 1. L. Chen et al., Hydrogen-doped high conductivity ZnO films deposited by radio-frequency magnetron sputtering. Applied Physics Letters 85 (2004) 5628. 2. S.Zhong et al., Exploring co-sputtering of ZnO:Al and SiO2 for efficient electron-selective contacts on silicon solar cells. Solar Energy Materials and Solar Cells 194 (2019) 67.
Authors : K. Jurai? (1), I. Pan?i? (1), M. Boha?ek (1), V. Koji? (1), A. Gajovi? (1), M. Plodinec (2), T. Rath (3), G. Trimmel (3)
Affiliations : (1) Ru?er Bo?kovi? Institute, Bijeni?ka cesta 54, 10000 Zagreb, Croatia; (2) Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany; (3) Institute for Chemistry and Technology of Materials (ICTM), NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria;
Resume : One of the methods to improve perovskite solar cells (PSC) performance is to change the mesoporous titania (TiO2) structure to a more ordered one, e.g. to nanorod or nanotube arrays. Oriented nanorod-like materials on transparent conductive oxide (TCO) are known for their efficient charge separation and transport properties and are thus favourable for achieving good device performance. In this work vertically aligned TiO2 nanotube (NT) array thin film based electrodes were prepared and tested for application in perovskite solar cells. A two-step process was employed and optimized for TiO2 NT array thin films preparation. It the first step titanium layer was deposited on TCO (ZnO, ITO) substrate by DC magnetron sputtering using titania target and argon as working gas. In the second step, TiO2 NT array was formed by electrochemical anodization of Ti layer. Anodization process parameters were optimized to obtain transparent TiO2 NT layer. Structural, optical and electrical properties of the prepared TiO2 NT electrodes were analyzed and discussed. Influence on PSC performance was also disused. Acknowledgement: This work has been supported by Croatian Science Foundation under the project IP-2018-01-5246 ?Nanocomposites comprising perovskites for photovoltaics, photo-catalysis and sensing? and Croatia-Austria bilateral project ?Titanium dioxide nanotube array based perovskite solar cells?.
Authors : F. Annoni (1), M.Cornelli (2), E. Achilli (3), N. Armani (2), F. Trespidi (2), F. Farina (2), E. Malvisi (2), N. Castagnetti (4),M. Patrini (3), L. Andreani (3), G. Timò (2)
Affiliations : (1) IMEM CNR Parco Area delle Scienze 37/A, 43124 Parma (Italy); (2) RSE SpA Strada della Torre della Razza 29122 Piacenza (Italy); (3) Dipartimento di Fisica UNIPV via Bassi 6, 27100 Pavia (Italy); (4) Istituto per lo Studio delle Macromolecole Via Alfonso Corti 12,20133 Milano (Italy).
Resume : High-efficiency III?V based multi-junction solar cells for terrestrial concentrated photovoltaics require broadband anti-reflection coatings (ARCs) working on wide angles. For this purpose, Ta2O5 and SiO2 coatings deposited by co-sputtering and e-beam evaporation in glancing angle conditions (GLAD) have been developed and characterized by combining ellipsometry and X-ray reflectivity data. Co-sputtering of Ta2O5 and SiO2 has been applied to obtain a ?mixed-oxide? with n matching any value in the range 1.5-2.2. GLAD evaporation has been carried out to nanostructure SiO2 films, in order to reduce its effective n and improve the ARC behaviour at high incident angles. The coating developed have been eventually deposited on InGaP SJ solar cell, to be used as top cell in a MJ cell structure. The cell short circuit current has then been measured in order to compare the performance of the different coatings.
Authors : Nivin Alktash(1), Ruslan Muydinov(1), Stefan Körner(1), Natalia Maticuic(2), Danny Kojda(3), Tobias Bertram(2), Ivona Kafedjiska(2), Monoj Baskarane(1), Klaus Habicht(3), Iver Lauermann(2), Bernd Szyszka(1)
Affiliations : (1)Technische Universität Berlin, Technologie für Dünnschicht-Bauelemente, Einsteinufer 25, 10587 Berlin, Germany (2)PVcomB, Helmholtz-Zentrum Berlin für Materialien und Energie, Schwarzschildstraße 3, 12489 Berlin, Germany (3)Transport Phenomena in Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
Resume : P-type transparent conductive oxides (TCOs) to be used as membrane layers in thin film solar cells to extract holes. In this work, we considered their application in monolithic CuInxGa1-xSe2 (CIGS) / hybrid perovskites (HPs) tandem cells. Therefore, materials with energy band gap (Wg) > 1.7 eV, low optical absorption in the energy range between 1.0 and 1.7 eV (the band gap of CIGS) but with high enough concentration of free charge carriers (> 1018 cm-3) were of our primary interest. Additional challenges to solve were mostly technological, they originated from low temperature resistance (TS ? 200°C) and high roughness of CIGS films. The latter is worsened by appearance of deep grain-grooves. The following materials were investigated: Cu2O, CuInO2, NiOx. Their conductivity and charge carrier concentration were measured in the correlation with oxygen content. For the Hall-effect measurements special mask was developed to enhance the accuracy. Reactive Hollow Cathode Gas Flow Sputtering (GFS) process was improved in this work. Monte-Carlo simulations were performed to optimize distribution of gases in a reactive area. A nozzle attachment was compared to the diffuser one in terms of their impact at the frontline of a high pressure drop. Optical Emission Spectroscopy (OES) was used to determine a composition of the GFS-plasma, namely, which species appear depending on conditions, such as the art of power generation, distance from the target, pressure and gas. Additionally, their ionization degree and energy distribution were determined.
Authors : Debashrita Sarkar, Venkataramanan Mahalingam
Affiliations : Department of Chemical Sciences and Centre of Advanced Functional Materials (CAFM), Indian Institute of Science Education and Research, Kolkata, India
Resume : Bi2SiO5 is a wide band gap semiconductor belonging to the aurivillius family.1-2 However, being a wide band gap semiconductor, it is effective for photocatalytic applications under UV light only.3-4 The objective of this work is to improve the photocatalytic activity of Bi2SiO5 by lowering the bandgap so that it can absorb both, UV and visible part of the solar light. In this work narrowing of band gap has been achieved by doping halides and its effect on the electronic and optical properties has been studied. The halide-doped Bi2SiO5 photocatalyst was synthesised via a facile hydrothermal approach. The phase, morphology and surface functionalization of the doped catalysts were retained in comparison to the pristine material which was examined by powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy and UV-vis diffuse reflectance spectroscopy. The doped Bi2SiO5 nanoparticles showed improved photocatalytic activity for the degradation of both coloured as well as colourless toxic water pollutants under simulated solar light. A small amount of halide doping lowered the band gap of Bi2SiO5 nanoparticles, broadened the optical absorption towards the visible region and escalated the charge separation of generated exciton pairs leading to reduced recombination rate and enhanced photocatalytic activity. The results obtained here show a rational design of halide doped Bi2SiO5 nanoparticles with an improved photocatalytic response. References: 1. Z. Wan and G. Zhang, Synthesis and facet-dependent enhanced photocatalytic activity of Bi2SiO5/AgI nanoplate photocatalysts, J. Mater. Chem. A 3 (2015) 16737-16745. 2. J. Duan, Y. Liu, X. Pan, Zhang, J. Yu, K. Nakajim, and H. Taniguchi, High photodegradation efficiency of Rhodamine B catalysed by bismuth silicate nanoparticles, Catal. Commun. 39 (2013) 65-69. 3. D. Liu, J. Wang, M. Zhang, Y. Liu and Y. Zhu, superior photocatalytic performance of a novel Bi2SiO5 flower-like microsphere via a phase junction, Nanoscale 6 (2014) 15222-15227. 4. J. Wang, G. Zhang, J. Li, and Kai Wang, Novel Three-Dimensional Flowerlike BiOBr/Bi2SiO5 p−n Heterostructured Nanocomposite for Degradation of Tetracycline: Enhanced Visible Light Photocatalytic Activity and Mechanism, ACS Sustainable Chem. Eng. 6 (2018) 14221−14229.
Authors : Elnaz Ebrahimi, Muhammad Irfan, Yusuf kocak, Farzan Shabani, Hilmi Volkan Demir ,Emrah Ozensoy
Affiliations : Department of Chemistry ,Bilkent university, Ankara, 06800, Turkey; UNAM- National Nanotechnology Research Center; Institute of Materials Science and Nanotechnology, Bilkent university, Ankara, 06800, Turkey.
Resume : Atmospheric pollution has been recognized as one of the major threats for modern society. Among the various manmade air pollutants, nitrogen oxides (NOx) induce the ozone production in troposphere and cause acid rains. In addition, NOx, especially nitric oxide (NO) and nitrogen dioxide (NO2) severely affect respiratory and immune systems . Titanium dioxide (TiO2) is the most widely used semiconductor for the photocatalytic decomposition of gaseous and liquid-phase pollutants. Despite its favorable properties like chemical inertness, long-term stability and low cost, TiO2 has a band gap of 3.2 eV. This large band gap enables the harvesting of UV light only, which accounts for 4-5% of incoming solar energy .There have been numerous attempts to extend the photocatalytic efficiency of TiO2 in the broader solar spectrum via nonmetal doping, metal doping, and surface modifications with polymers. In this study, oleic acid capped CdSe/CdSeTe nanoplatelets (NPLs) were synthesized for the surface functionalization of TiO2. Structural characterizations were carried out by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) , ATR-Fourier-transform infrared spectroscopy, transmission electron microscopy (TEM) to confirm the formation of desired materials. These NPLs/TiO2 composites were then tested in NO photo-oxidation under UVA and visible light, showing a remarkable activity in NOx abatement and a high selectivity for nitrate species as compared to standard benchmark TiO2 photocatalyst. The improved photocatalytic property can be attributed to decrease in bandgap and enhanced photogenerated electron-hole pair separation as a result of incorporation of CdSe/CdSeTe NPLs to TiO2. The stability of composites was investigated by extension of reaction duration. Even though some decrease in photocatalytic activity and selectivity of NPLs/TiO2 composites observed, but their performance was even significantly better than pure TiO¬2¬. This facile synthesis approach in combination with a high performance present a valuable material for next generation technologies for the abatement of harmful gaseous pollutants.
Authors : M. Filipescu1, F. Andrei1, V. Ion1, I. Boerasu1, A. Calugar1,2, E. Sirjita1,2, N. Scarisoreanu1, M. Dinescu1
Affiliations : 1. The National Institute for Lasers, Plasma & Radiation Physics, 409 Atomistilor Street, Magurele, Romania 2. University of Bucharest, Faculty of Physics, 405 Atomistilor, P.O. BOX MG-11, 077125, Magurele, Romania
Resume : Nowadays, the producing of hydrogen for energy storage with low costs and high efficiency is the main concern in the research filed. The photovoltaic devices that are renewable energy sources can be used in the photovoltaic-electrolysis process to produce hydrogen. Extended studies were performed on the wide band gap semiconductor oxides for solar water splitting systems. Therefore, in this work, nanostructured metal oxides based on tungsten are studied and produced as thin films and their properties are tuned by the embedding of nitrogen ions in their contents. These thin films are produced by pulsed laser deposition. The deposition parameters such as laser wavelength, gas composition, and laser fluence influence the nanostructures physical and chemical properties. The morphological, structural, and compositional characterization of the obtained structures was performed. The testing of photocatalytic activity of WO3 and WOxNy thin layers in the photochemical decomposition reaction of the water molecule was pursued.
Authors : Ana Rovisco*, Andreia dos Santos, Rui Igreja, Rita Branquinho, Elvira Fortunato, Rodrigo Martins and Pedro Barquinha*
Affiliations : i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA Campus de Caparica, 2829-516 Caparica, Portugal *E-mail: email@example.com, firstname.lastname@example.org
Resume : Recently, metal oxide nanostructures had great development regarding their synthesis and device integration. Having in mind sustainability of materials and processes as well as multifunctionality, zinc-tin oxide nanostructures are some of the most promising oxide nanostructures being researched. The ternary oxide nature allows for impressive multifunctionality, with applications ranging from catalysis, to electronics, sensors and energy harvesting. Concerning energy harvesting applications ZnSnO3 phase is particularly interesting, due to its high piezoelectric constant. Although a pure phase of ZnSnO3 is hard to achieve due to its metastability, in this work ZnSnO3 NWs produced by a seed-layer free hydrothermal synthesis at only 200 °C are presented.1 In order to produce robust energy harvesters, a composite was fabricated mixing these NWs with a micro-structured PDMS film2. The micro-structured nature enabled a double contribution, enhancing both tribo and piezoelectric effects, resulting in a great performance regarding output voltage, current, and instantaneous power density (up to 200 µW·cm-2). As proof of concept, a demonstration of lighting up multiple LEDs by directly connecting them to the fabricated harvester is also shown, evidencing the great potential for wearables and portable electronics.3  A. Rovisco, et. al., ACS Appl. Nano Mater. 1(8), 3986 (2018)  A. dos Santos, et. al., Adv. Electron. Mater. 4(9), 1 (2018)  A. Rovisco, et. al., submitted (2019)
Authors : Rui Xu
Affiliations : College of Chemical Engineering Nanjing University of Science & Technology 200 Xiaolingwei Nanjing, 210094, China
Resume : The nanomaterials have attracted enormous attention in the catalysis applications. Particularly, we have concentrated on the synthesis of nanocomposites for an electrochemical sensor with improved electrocatalytic performance. Over the past few decades, a great number of studies have demonstrated that graphene oxide (GO) could be used successfully for the removal of Pb (II) from water. Thus, tungsten oxide (WO3) embellished on reduced graphene oxide could be applied in degradation of water for removing the waste ions in it by electrocatalysis. We report a simple and robust ultrasonic-assisted synthetical route via prepared WO3 nanoparticles decorated reduced graphene oxide nanocomposite (GO-WO3) modified electrode for nitrite detection. The composition and morphological formation were characterized by XRD, XPS, FESEM, and HRTEM. Except for valuable information about the characteristics, our results provide and mechanism of transport of adsorbed heavy metals on GO-WO3 nanomaterials in the aqueous environment and the possible environmental risks when spent GO-based heavy mental adsorbents are discharged into natural groundwater systems.
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|09:00||Plenary session (Main Hall)|
|13:55||Joint session Symposia L&M. Theory and experiment. Chairs: Martin Eickhoff and Smagul Karazhanov|
Authors : Su-Huai Wei
Affiliations : Beijing Computational Science Research Center, Beijing 100193, China
Resume : Transparent conducting oxides (TCOs), which combine high electrical conductivity and high optical transmission in the visible spectral range, are needed in many modern optoelectronic devices, such as solar cells, flat-panel displays, touch-screen sensors, light emitting diodes and transparent thin film transistors. In this talk, I will highlight our study on the band structure and doping control of TCOs. In particular, I will discuss (i) the fundamental band structures and defect properties for the TCOs; (ii) how to achieve simultaneously high transparency and conductivity in n-type TCOs; (iii) why p-type TCOs are difficult to achieve; (iv) how to modify the band structure or design new materials to achieve p-type TCOs or even bipolarly dopable TCOs. Based on the understanding above, we hope to provide useful guidelines for the rational design of novel TCOs that are critical for the development of the next-generation optoelectronic materials.
Authors : Marco Altomare
Affiliations : Department of Materials Science and Engineering WW4-LKO, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany. E-mail: email@example.com
Resume : Photocatalytic H2 evolution on virtually any pristine semiconductor surface is characterized by low efficiencies due to trapping and recombination of charge carriers, and due to a sluggish kinetics of charge transfer (1). Thus, co-catalyst metal nanoparticles are typically decorated at the semiconductor surface to reach reasonable photocatalytic yields. For this, most common strategies involve wet chemical methods, e.g. impregnation, chemical reduction or photo-deposition. An intriguing, alternative pathway is ?solid state dewetting?: as-deposited thin (nm-thick) metal films on a given surface are usually metastable and when heated to a certain temperature tend to ?dewet?, i.e. they break up and aggregate into defined metal particles (2). Factors such as the initial metal film thickness and composition, treatment temperature, atmosphere and time, can influence morphological and physicochemical features of the dewetted particles (2,3) (e.g. shape, size, dispersion, composition and crystallinity, among others) that are key for their co-catalytic ability in photocatalytic reactions. This talk discusses the use of dewetting as a precise nanostructuring tool to form functional metal nanoparticles at highly-defined TiO2 nanotube surfaces (4), namely to engineer catalyst/semiconductor platforms for light-driven reactions. In particular, we discuss how metal dewetting, steered in size, order, and composition, and synergistically combined with additional self-ordering principles (e.g. alloying, dealloying), can enable various types of functionalization of semiconductor surfaces for photocatalytic applications (5?8). (1) Takanabe, K. ACS Catal. 2017, 7 (11), 8006?8022. (2) Thompson, C. V. Annu. Rev. Mater. Res. 2012, 42 (1), 399?434. (3) Leroy, F.; Borowik, ?.; Cheynis, F.; Almadori, Y.; Curiotto, S.; Trautmann, M.; Barbé, J. C.; Müller, P. Surf. Sci. Rep. 2016, 71 (2), 391?409. (4) Yoo, J. E.; Lee, K.; Altomare, M.; Selli, E.; Schmuki, P. Angew. Chemie Int. Ed. 2013, 52 (29), 7514?7517. (5) Nguyen, N. T.; Altomare, M.; Yoo, J.; Schmuki, P. Adv. Mater. 2015, 27 (20), 3208?3215. (6) Altomare, M.; Nguyen, N. T.; Hejazi, S.; Schmuki, P. Adv. Funct. Mater. 2018, 28 (2), 1704259. (7) Spanu, D.; Recchia, S.; Mohajernia, S.; Schmuki, P.; Altomare, M. Appl. Catal. B Environ. 2018, 237 (May), 198?205. (8) Spanu, D.; Recchia, S.; Mohajernia, S.; Tomanec, O.; Kment, ?.; Zboril, R.; Schmuki, P.; Altomare, M. ACS Catal. 2018, 8 (6), 5298?5305.
Authors : Marco Arrigoni, Georg K. H. Madsen
Affiliations : Institute of Materials Chemistry, TU Wien, A-1060 Vienna, Austria
Resume : The growing interest for environmental protection and the pursuit for renewable and clean energy sources have made the TiO2-assisted photoelectrochemical water splitting a very active research area. For such application, TiO2 nanoparticles are commonly used due to their superior performances, with anatase being the most commonly observed polymorph in small particles. The study and characterization of native point defects is of paramount importance for understanding the electronic properties of the material and the impact on the photocatalytic activity. Moreover, native defects play a fundamental role also in doped systems, where they can compensate for the defect-introduced carriers. Although several first-principles studies of native point defects in TiO2 anatase exist, they are mostly consider a few of them at a time. The different levels of theory employed in the literature do not allow for a direct calculation of the equilibrium concentrations as different formation energies are often reported with different functionals and corrections schemes.In this study, we comprehensively investigate the stability of native point defects in TiO2 anatase using the GGA+U approach. All native point defects and their ionized states are considered. We systematically compare state-of-the-art methods for obtaining reliable formation energies and correcting for finite-size-errors. Equilibrium defect and carriers concentrations are then calculated with respect to different growth conditions.
Authors : J. Dolado(1), P. Hidalgo(1), A. M. Sánchez(2) and B. Méndez(1)
Affiliations : 1 Department of Materials Physics. Faculty of Physics, Complutense University of Madrid, E-28040 Madrid, Spain 2 Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom
Resume : Semiconductor oxides nanowires (NWs) are an excellent benchmark to produce complex nanostructures, which could lead to novel architectures in a NW-heterostructure morphology with enhanced physical properties. Recently, wide band gap oxides, such as Zn2GeO4, are emerging as potential candidates for applications in high power devices or in ultraviolet-solar blind photodetectors . In this work, we report the synthesis and characterization of complex nanostructures of oxide NWs in which Zn2GeO4 NWs combine with SnO2 particles, in a self-organized manner. The synthesis method is the thermal evaporation of the suitable chemical precursors on a catalyst-free basis via a vapour-solid mechanism. Electron microscopy measurements have been carried out to assess the morphology, the microstructure and determine the orientation of the NWs. The results support a model growth in which the Plateau-Rayleigh mechanism  would produce a pattern of germanium oxide amorphous particles along the Zn2GeO4 NW. In addition, under suitable kinetic conditions, these particles act as nucleation sites for well-faceted SnO2 crystals. The luminescence properties have been assessed by means of cathodoluminescence and photoluminescence techniques. In addition, optical confinement effects have been observed, what could be further exploited in the design of optical microcavities. References  H. Mizoguchi, T. Kamiya, S. Matsuishi, H. Hosono, ?A germanate transparent conductive oxide?, Nature Communications, 2, 470 (2011).  R. W. Day, M. N. Mankin, R. Gao, Y. No, S. Kim, D. C. Bell, H. Park and C. M. Lieber, ?Plateau?Rayleigh crystal growth of periodic shells on one-dimensional substrates? Nature Nanotechnology, 10, 345 (2015).
|15:55||Joint session Symposia L&M. Advanced characterization and materials properties. Chairs: Michael Heere|
Authors : Ulrike Boesenberg
Affiliations : European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
Resume : Many materials for energy storage undergo phase transformations to store and release the energy in form of hydrogen, ions or electrons involving mass transport. To understand and finally overcome the rate limiting processes detailed understanding of the systems is necessary. This includes the structure of crystalline systems, the reaction pathway with possible metastable phases as well as the mesoscale to identify inhomogeneities and long term effects. Here X-rays, especially synchrotron radiation, can provide a wide range of methods spanning from XRD to characterize the crystalline phases, spectroscopy to characterize chemical species to spatially resolved techniques (X-ray microscopy) or combinations thereof. This presentation will show some examples for different techniques and results from metal hydrides for hydrogen storage, intercalation and conversion materials for Li-ion batteries and catalyst particles. With the advance of X-ray free electron lasers the door has opened to directly study ultrafast phenomena such as i.e. nucleation also in the time domain.
Authors : Claudia Zlotea and Jorge Montero
Affiliations : Institut de Chimie et des Matériaux de Paris Est, CNRS-UPEC
Resume : Multi-Principal-Element Alloys (MPEAs) belong to a new metallurgical paradigm based on the alloying of four or more elements with equal concentrations. Most of reports concerning these alloys describe their structure, microstructure and mechanical properties, whereas functional properties such as, hydrogen sorption, are only scarcely investigated. We present here the study of hydrogen absorption properties of MPEAs based on refractory metals. The TiVZrNbX (X = Mg, Al and Ta) alloys have been synthesized by classical high temperature methods or mechanosynthesis under inert atmosphere. To directly produce hydrides we have employed the reactive ball milling under hydrogen gas starting from the pure metal powders. The properties of materials have been studied by several experimental techniques: X-ray diffraction, electron microscopy, neutron diffraction, pressure-composition-isotherm, thermal desorption spectroscopy. All the alloys are bcc single-phased and undergo one-step reaction with hydrogen. We suggest that the lattice distortion, δ, might play an important role: larger δ would favours a single-step reaction, whereas small δ would favour a two-steps phase, as encountered for conventional bcc alloys. The hydrogen absorption/desorption is completely reversible and the capacities varies between 2 and 3 wt%. In summary, this is an original research topic in the field of solid-state hydrogen storage that might open new routes for the design of multifunctional materials.
Authors : Hai-Wen Li1, Kaveh Edalati1, Ryoko Uehiro, Yuji Ikeda2,3, Hoda Emami1, Yaroslav Filinchuk4, Makoto Arita1, Xavier Sauvage5, Isao Tanaka2, Etsuo Akiba1 and Zenji Horita1
Affiliations : 1 Kyushu University, Fukuoka 819-0395, Japan 2 Kyoto University, Sakyo, Kyoto 606-8501, Japan 3 Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany 4 Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium 5 Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, 76000, Rouen, France
Resume : MgH2 is one of the most investigated solid-state hydrides as promising hydrogen storage materials due to its large hydrogen capacity of 7.6 mass% and the high abundance of Mg in Earth's crust. The high thermodynamics (-75 kJ/mol H2) of MgH2 originated from the strong Mg-H binding energy results in the serious issue of high dehydrogenation temperature, i.e. above 300°C for pure MgH2. Forming an alloy with a hydride non-forming transition metal has been approved to be a feasible approach to destabilize MgH2. For example, when alloying with Ni to form a binary Mg2Ni, the hydride transforms from MgH2 to Mg2NiH4, and the enthalpy is reduced from -75 to -64 kJ/mol H2. Ternary alloys like RMg2Ni9 and (Mg,Ca)Ni2 can further destabilize MgH2 and can absorb and desorb hydrogen at room temperature, whereas the gravimetric hydrogen capacity is limited due to the Ni-rich composition. It is hard to produce an Mg-based ternary alloy with a homogeneous elemental distribution by melting process because of the thermodynamic immiscibility of Mg in many systems. This technical issue may be solved by the application of severe plastic deformation using high-pressure torsion (HPT). In this study, a new Mg-rich ternary alloy Mg4NiPd was designed and prepared successfully by HPT. Preliminary results indicate hydrogen absorption and desorption proceed at room temperature, suggesting a new approach to design and prepare Mg-based alloys exceed the scope of known equilibrium phase diagrams for room temperature hydrogen storage.
Authors : A.G. Kvashnin, I.A. Kruglov, D.V. Semenok, A.R. Oganov
Affiliations : Skolkovo Institute of Science and Technology, Skolkovo Innovation Center 121205, 3 Nobel Street, Moscow, Russia, Moscow Institute of Physics and Technology, 141700, 9 Institutsky lane, Dolgoprudny, Russia; Dukhov Research Institute of Automatics (VNIIA), Moscow 127055, Russia, Moscow Institute of Physics and Technology, 141700, 9 Institutsky lane, Dolgoprudny, Russia; Skolkovo Institute of Science and Technology, Skolkovo Innovation Center 121205, 3 Nobel Street, Moscow, Russia; Skolkovo Institute of Science and Technology, Skolkovo Innovation Center 121205, 3 Nobel Street, Moscow, Russia; Dukhov Research Institute of Automatics (VNIIA), Moscow 127055, Russia, Moscow Institute of Physics and Technology, 141700, 9 Institutsky lane, Dolgoprudny, Russia, Northwestern Polytechnical University, Xi'an, 710072, China;
Resume : Hydrogen-rich hydrides attract great attention due to recent theoretical  and then experimental discovery of record high-temperature superconductivity in H3S (TC = 203 K at 155 GPa ). Here we perform a systematic evolutionary search for new phases in the Fe-H , Th-H , U-H  and other numerous systems under pressure  in order to predict new materials which are unique high-temperature superconductors. We predict new hydride phases at various pressures using the variable-composition search as implemented in evolutionary algorithm USPEX [7-9]. Among the Fe-H system two potentially high-TC FeH5 and FeH6 phases in the pressure range from 150 to 300 GPa were predicted and were found to be superconducting within Bardeen-Cooper-Schrieffer theory, with TC values of up to 46 K. Several new thorium hydrides were predicted to be stable under pressure using evolutionary algorithm USPEX, including ThH3, Th3H10, ThH4, ThH6, ThH7 and ThH10. Fm3 ̅mThH10 was found to be the highest-temperature superconductor with TC in the range 221-305 K at 100 GPa. Actinide hydrides show, i.e. AcH16 was predicted to be stable at 110 GPa with TC of 241 K. To continue this theoretical study, we performed an experimental synthesis of Th-H phases at high-pressures including ThH10. Obteined results can be found in Ref. . Acknowledgments: Authors thank RFBR foundation № 19-03-00100. This work was supported by RFBR foundation № 19-03-00100 and facie foundation, grant UMNIK №13408GU/2018. References  D. Duan et al., Sci. Rep. 2018, 4, 6968.  A.P. Drozdov et al. Nature. 2015, 525, 73–76.  A.G. Kvashnin at al. J. Phys. Chem. C 2018, 122 4731-4736.  A.G. Kvashnin et al. ACS Applied Materials & Interfaces 2018, 10, 43809–43816.  I.A. Kruglov et al. Sci. Adv. 2018, 4, eaat9776.  D.V. Semenok et al. J. Phys. Chem. Lett. 2018, 8, 1920-1926.  A.O. Lyakhov et al. Comp. Phys. Comm. 2013, 184, 1172-1182.  A.R. Oganov et al. J. Chem. Phys. 2006, 124, 244704.  A.R. Oganov et al. Acc. Chem. Res. 2011, 44 227-237.  D.V. Semenok et al. 2019, arXiv:1902.10206.
|18:00||Graduate Student Awards Ceremony & Reception 18:00-21:00 (Main Hall)|
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|08:55||Session XIII. Energy storage and sensing. Chairs: Marco Altomare and Esra Ozkan Zayim|
Authors : Neslihan Yuca, Bü?ra Çetin
Affiliations : 1 Enwair Energy Technologies Corporation, Istanbul, Turkey 2 Maltepe University, Istanbul, Turkey
Resume : Lithium ion batteries, which are the most widely used among the secondary battery types, have high capacities and cycling life. The most important characteristic of the batteries is that they can store electrical energy better than competing technologies, they can be used for a long time, and their energy density are better than other battery technologies. These batteries are widely used in smart devices, laptops, tablets etc. in portable devices, smart home systems, and electrical vehicles. The lithium-ion batteries are mainly composed of positive electrode (cathode), negative electrode (anode), electrolyte and separator. A positive electrode is the lithium ion source which is consisting of transition metal oxides, such as LiCoO2, LiMn2O4. The negative electrode hosts lithium ions. While the electrolyte provides ionic conductivity, the separator is used to separate the electrodes. During the charging process, Li ions are extracted from the positive electrode and form a compound on the negative electrode. The theoretical capacity of lithium ion batteries is expected to remain at the same value in each cycle without changing the ingredients. However, this does not take place as expected and lithium ions in the battery can be produced or consumed by side reactions during charging/discharging. When the capacity stability of the battery deteriorates, there is a loss of capacity and a significant decrease in the performance of the battery occurs in long cycles. Anode and cathode materials of the batteries directly affect the capacity and cycle life. Lithium rich layered metal oxides are a high energy density cathode material for new generation lithium-ion batteries (LIBs). This cathode materials have Li[Li1/3Mn2/3]O2 and LiMO2 (M: Ni, Co, Mn, Al etc.) structure and exhibit higher irreversible capacity and cycle life than conventional cathode materials. Nano-sized Li-rich layered metal oxides shorten the electronic/ionic transfer path, facilitating the diffusion of lithium ions and effectively enhancing performance. The lithium van der walls are placed in the gaps and the material has a performance exceeding 280 mAh/g capacity. The nominal voltage is ~4.2 V. There are transition metals with different properties within the structure. The lithium rich cathode material consists of lithium as well as transition metal layers such as Ni, Co and Mn, and incorporates the beneficial effects of these metals. Nickel increases capacity and Mn increases thermal stability while cobalt improves the capacity retention rate performance of the battery. Apart from this, doping of metals such as Al, Zn, Nb, Mg, Fe etc. is increased to performance. In this study, the stoichiometry of metals in the lithium rich cathode material formulation was investigated by changing Mn, Ni and Co ratios. Li1.2MnxCoyNizAl0.02 (x:0.50;0.51;0.52, y:0.14;0.16;0.18, z:0.14;0.16;0.18) formulation was used and the prepared lithium rich cathode active powders were structurally characterized by XRD and Li-rich cathodes were tested by electrochemical methods.
Authors : Kosuke Beppu, Takayuki Shimasaki, Ichiro Fujii, Takahiro Wada
Affiliations : Department of Materials Chemistry, Ryukoku University Graduate Faculty of Interdisciplinary Research, University of Yamanashi
Resume : Antiferroelectrics have been studied as energy storage capacitors due to their higher energy storage density than ferroelectrics and paraelectrics. Environmental concerns for toxic lead have focused studies on lead-free antiferroelectric materials. Recently, we reported that the 0.92NaNbO3-0.08SrZrO3 (NNSZ8) thin film was fabricated on a (110) SrTiO3 (STO) single crystal substrate by a pulsed laser deposition (PLD). The NNSZ8 film showed a double polarization-electric field (P-E) hysteresis loop. In this study, in order to increase the energy storage density, the NNSZ8 thin films were fabricated on a SrRuO3(SRO)-coated (001) STO substrates. The NNSZ8 films with a thickness of about 1.0 ?m were epitaxially grown on the SRO/(001)STO substrate. SEM observation revealed that the NNSZ8 films had flat surface morphology. X-ray reciprocal space mapping indicated that the films had antiferroelectric domains. Their insulation performance was sufficiently high. The double P-E hysteresis loop could also be observed for the NNSZ8/SRO/(001)STO film at room temperature but also at high temperature of 150 oC. The remanent polarization of the NNSZ8/SRO/(001)STO film was closer to zero. Therefore, the present NNSZ8/SRO/(001)STO film had higher energy storage density than the previously reported NNSZ8/SRO/(110)STO film.  I. Fujii, T. Shimasaki, T. Nobe, H. Adachi, and T. Wada, Jpn. J. Appl. Phys., 57, 11UF13 (2018).
Authors : Martynas Lelis, Simona Tuckute, Sarunas Varnagiris, Marius Urbonavicius, Kristina Bockute, Giedrius Laukaitis
Affiliations : Martynas Lelis, Simona Tuckute, Sarunas Varnagiris, Marius Urbonavicius: Centre for Hydrogen Energy Technologies, Lithuanian Energy institute, Breslaujos st. 3, Kaunas 44403, Lithuania. Kristina Bockute, Giedrius Laukaitis: Centre for Hydrogen Energy Technologies, Lithuanian Energy institute, Breslaujos st. 3, Kaunas 44403, Lithuania. and Department of Physics, Kaunas University of Technology, Studentu Str. 50, LT-51368 Kaunas, Lithuania.
Resume : Zinc oxide is one of the best photocatalyst for the UV-light sensitised water treatment technologies. Various dopants allow to narrow its band gap and extends its activity to the visible light spectra but for practical applications its properties must get further improvements. The main objective of the current work was to synthesise and test ZnO oxide doped with Zinc metal. For this ZnO based photocatalyst films were deposited using magnetron sputtering with in-situ control of the physical vapor phase composition. Precise monitoring and control of Zinc, Argon and oxygen content in the plasma phase allowed to identify small range of parameters which led to the formation of samples in the intermediate zone between metallic Zn and completely oxidised ZnO phase. Photocatalytic bleaching of Methylene Blue and Rhodamine B in aqueous solution has demonstrated that in such samples metallic zinc acts as a dopant and up to some extent improves the photocatalytic efficiency of ZnO oxide. The relationship between magnetron sputtering process parameters and film properties (crystal phase, elemental and chemical composition, surface roughness, optical properties) are provided and their influence to the high photocatalytic activity of the films is discussed.
Authors : P. Nowak, W. Maziarz, A. Rydosz, K. Zakrzewska, K. Kowalski, M. Zi?bka
Affiliations : AGH University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, al. Mickiewicza 30, 30-059 Krakow, Poland; AGH University of Science and Technology, Faculty of Metals Engineering and Industrial Computer Science, al. Mickiewicza 30, 30-059 Krakow, Poland; AGH University of Science and Technology, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Krakow, Poland
Resume : Nitrogen dioxide (NO2) is a highly reactive, hazardous gas and a prominent air pollutant that should be detected at very low concentrations in the ppb rather than ppm range. Low threshold, highly sensitive and selective detection of NO2 by SnO2 has lately appeared as a particularly important issue [1,2]. In this work, thin-film nano-heterostructures of SnO2/TiO2, highly sensitive to NO2, were obtained in a two-step process: (i) magnetron sputtering, MS followed by (ii) Langmuir-Blodgett, L-B, technique. Morphology, crystallographic and electronic properties of the films were studied by SEM, XRD in glancing incidence geometry, XPS, UV-VIS-NIR spectrophotometry, respectively. It was found that amorphous SnO2 thin films detected relatively low concentrations of NO2 of about 200 ppb. More than two orders of magnitude change in the electrical resistivity upon exposure to NO2 was further enhanced in SnO2/TiO2 to reach a three-fold giant gas response. The best sensor responses were obtained at the lowest operating temperatures of about 120oC which is typical for nanomaterials. National Science Centre, Poland project 2016/23/B/ST7/00894 is acknowledged.  A. Sharma et al., Sensors Actuators B. 181 (2013) 735?742  J.H. Bang, et al., Sensors Actuators B. 274 (2018) 356?369. doi:10.1016/J.SNB.2018.07.158.
Authors : Mikhail Simonov 1,2, Yulia Bespalko 1,2, Ekaterina Smal 1, Valeria Fedorova 1, Konstantin Valeev 1, Alexey Krasnov 1
Affiliations : 1. Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia; 2. Novosibirsk State University, Novosibirsk, Russia
Resume : Methane dry reforming of is a promising way to convert both greenhouse gases, as well as a model reaction to study the transformation of other fuels. Nickel based catalysts attract attention because of their high activity but the main disadvantage is the rapid deactivation due to carbonization and blocking of the Ni centers. Promising supports of Ni catalysts are oxides with high oxygen mobility for gasification of coke precursors to increase stability. Oxygen mobility and reactivity of Ce-Zr oxide can be increased by introducing additional cations. However, the synthesis of single phase mixed oxides by traditional methods (co-precipitation, Pechini) is a challenge. In this work, samples of catalysts based on Ti and Nb-doped Ce-Zr single-phase oxides were synthesized and characterized in detail. Samples of complex oxides were synthesized in supercritical alcohols in flow-through mode, followed by impregnation with Ni, drying and calcination. Samples were investigated by means of XRD, IR, Raman, TEM, XPS. The catalytic activity was studied in methane and ethanol dry reforming using fixed bed reactors. The introduction of cations changes the electronic properties of oxides, the oxidation state and the concentration of cerium and nickel on the surface. The highest catalytic activity is achieved on a sample doped with Nb, while the sample, jointly doped with Nb and Ti, exhibits the lowest deactivation rate. The study was funded by the Russian Science Foundation (Project 18-73-10167).
|10:55||Session XIV. Oxides and oxyhydrides. Chairs: Neslihan Yuca and Vishnukanthan Venkatachalapathy|
Authors : L.Khomenkova 1,2,3, D. Lehninger4, E. Agocs5, X. Portier2, P. Petrik5, T. Torchynska6, O. Meknichuk7,F. Gourbilleau2, J. Heitmann4
Affiliations : 1) V. Lashkaryov Institute of Semiconductor Physics, 45 Pr. Nauky, Kyiv 03028, Ukraine; 2) CIMAP Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, 6 Boulevard Maréchal Juin, 14050 Caen Cedex 4, France ; 3) National University ?Kyiv-Mohyla Academy?, 2 Skovorody str., Kyiv, 04170, Ukraine; 4) Institute for Technical Physics and Materials Science (MFA), Center for Energy Research (EK), Hungarian Academy of Sciences (MTA), Konkoly Thege Rd. 29-33, 1121 Budapest, Hungary; 5) Institute of Applied Physics, TU Bergakademie Freiberg, D-09596 Freiberg, Germany; 6) Instituto Politécnico Nacional - ESFM, México City, 07738, Mexico; 7)Mykola Gogol State University of Nizhyn, 2 Hrafska Str., Nizhyn 16600, Ukraine
Resume : HfO2-based thin films are mostly considered as high-k dielectrics for microelectronics. However, doped with different ions, they can offer promising optical applications. In this work, the effect of doping and processing conditions on structural and optical properties of the HfO2 films doped with different elements (Si, Ge, N) grown by radio-frequency magnetron sputtering was studied by means of spectroscopic ellipsometry, FTIR, SEM, TEM and photoluminescence (PL) methods. It was observed that the film morphology depends significantly on the deposition atmosphere. The films grown in Ar plasma showed the presence of grains with a mean size about 100?nm. Post annealing treatments result in a phase separation process and formation of tetragonal HfO2 and SiOx (or GeOx) phases. The films grown with Ar-N2 plasma were found to be denser and smoother whatever the annealing temperature. Thermal treatments stimulate the formation of tetragonal HfO2 phase as well as the SiOxNy (or GeOxNy) phases that was confirmed by FTIR spectra. The PL spectra of all annealed films showed broad PL band in the UV-visible spectral range. The shape of PL band depends on the contribution of different host defects. Their nature and the mechanism of phase separation are analyzed and discussed in details.
Authors : Maguy Abi Jaoude, Swati Sood, Ahmad Safieh, Aaesha Alnuaimi, Marco Stefancich
Affiliations : Maguy Abi Jaoude, Department of Chemistry, Khalifa University of Science and Technology, Center for Membranes & Advanced Water Technology, Abu Dhabi, UAE; Swati Sood, Department of Chemistry, Khalifa University of Science and Technology, Abu Dhabi, UAE; Ahmad Safieh, Research and Development Centre, Dubai Electricity and Water Authority (DEWA), Dubai, UAE; Aaesha Alnuaimi, Research and Development Centre, Dubai Electricity and Water Authority (DEWA), Dubai, UAE; Marco Stefancich, Research and Development Centre, Dubai Electricity and Water Authority (DEWA), Dubai, UAE;
Resume : Enhancing the performance of the omnipresent TiO2 photocatalyst by intercepting the inherent shortfalls that prompt its short-lived charge carriers and poor visible-light sensitization, is a hot topic in solar-driven oxidative water-treatment. Nanoscale heterojunction coupling of TiO2 with semiconductor metal-oxide co-catalysts may offer an advantageous way to tailor its photo-inducible energy harvesting ability and electron-transfer properties via the inclusion of synergistic quantum interactions. Both CeO2 and Bi2O3 in its alpha- and beta- polymorphs, are attractive dopant materials owing to their suitable band-gap edge positions for triggering the visible-light activity and enhancing the charge carrier separation. [1,2] CeO2 may particularly offer room-temperature oxygen storage capacity and rapidly interchangeable oxygen lattice species, through its highly active Ce3 /Ce4 redox couple, allowing thus to improve the overall degradation kinetics. In this context, we demonstrate the in-situ fabrication of novel TiO2-CeO2-Bi2O3 nano-heterojunction structures anchored in open-tubular silica capillaries, which can be simultaneously deployed as microreactors and optical light guides in continuous-flow photocatalysis. The synthesis is accomplished via sol-gel assisted solvothermal growth methodology, using titanium(IV) n-propoxide, cerium(III) and bismuth(III) nitrates as metal-oxide precursors, in addition to stabilizing and structure directing additives. Ti(IV)-rich mixtures, with fixed and varied proportions of cerium and bismuth oxide precursors respectively, are prepared in ice-bath, loaded into pre-activated hollow optical fiber silica capillaries, then subjected to solvothermal treatment at 100 °C for 24 hours, and subsequently carefully dried and calcined up to 350 °C. In this work, we particularly examine the role of the Bi(III)-dopant concentration (0.5-5 %mol) as well as the calcination temperature (300-350°C) and ramp, on tuning the microscopic morphology, crystal structure and optical absorption properties of the photocatalysts for solar-light sensitization. Initial structure-to-performance relationships of elementary photocatalytic reactors are established in correlation with the continuous-flow degradation of model chlorophenol compounds in water.  L.T.T. Tuyen et al. J. Environ. Chem. Eng. 6 (2018) 5999.  X. Xiao et al. Appl. Catal. B ? Environ. 140-141 (2013) 433.
Authors : D. Mamedov, E. M. Baba, S. Zh. Karazhanov
Affiliations : Department of Materials Science, National Research Nuclear University, 115409 Moscow, Russia, Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway; Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway; Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway;
Resume : Oxyhydrides have attracted great attention in recent years due to their photochromic, magnetic, high temperature superconducting, and photocatalytic properties. In this work, we focused on cerium oxyhidride (CeHO), which may show the same properties as other lanthanide oxyhydrides. Using Bärnighausen tree based spacegroups method, we have predicted possible crystal structures of CeHO. We report that, according to the ab initio calculations, several different structures show mechanical stability at 0K and might coexist at the same conditions. Lattice parameters and X-ray diffraction pattern have been derived. Electronic and optical properties for these stable phases are calculated by first-principles calculations within generalized gradient approximations and hybrid functional. We found that CeHO is a wide band gap material. Spin-polarized spectra detect magnetic properties existing for this oxyhydride. Distinct from CeO2 with Ce-4f located inside the band gap, the Ce-4f orbitals are inside conductive band and are less localized.
Authors : R. Magri, G. Righi
Affiliations : Dipartimento di Fisica, Informatica e Matematica (FIM) dell? Università degli Studi di Modena e Reggio Emilia, and Istituto di Nanoscienze CNR-S3 , via Campi 213/A, 41100 Modena, Italy
Resume : Single atom catalysis (SAC) is the new frontier of heterogenous catalysis where the catalyst consists of single metal atoms dispersed on a support . Reducibile oxides, such as, cerium oxides, CeO2-x, and iron oxides, Fe3O4 and ?-Fe2O3, are an explored possibility as possible supports, while the single atoms catalysts are constituted by single noble metal atoms dispersed on the oxides. Density functional calculations (DFT) have been carried out to investigate the oxide surfaces, their stability and reducibility, and the preferred configurations for the noble metal atoms in absorption, and Ce(Fe) substitutional sites. We have found the most stable reconstruction for the maghemite (001) surface, and the increased reducibility of maghemite surfaces compared to the corresponding magnetite ones. The reasons for the increased reducibility have been investigated. Also, our results show a larger stability of absorbed atoms on the surfaces of iron oxides than on ceria oxides. Finally, we have investigated single Ag catalysts for H2 dissociation on ceria, and compared them to Cu and Au. We have found that when a single nobel metal atom is adsorbed on CeO2, the activation energies drop with respect to those of pure ceria, and they are slightly lower for Ag than Au and Cu. Instead, when the noble metals substitute a Ce atom, we have calculated only for Ag a significative decrease of the barrier energy.   J. Liu, ACS Catal. 7, 34 (2017).
Authors : S. Santucci, H. Zhang, S. Sanna, N. Pryds, V. Esposito.
Affiliations : Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Frederiksborgvej 399, 4000, Roskilde, Denmark.
Resume : The recent discovery of ?non-classical? electrostriction in gadolinium-doped ceria (Ce1-xGdxO2-?) (CGO)  attracts a great interest as it opens to a novel generation of biocompatible devices with exceptional electromechanical performances. CGO is a non-piezoelectric material with an electrostriction coefficient that overcomes traditional PZT materials by several orders of magnitude, e.g. Q= 0.02 m4/C2  for Pb(Mg1/3Nb2/3)O3 versus Q= 400 m4/C2 for Ce0.8Gd0.2O2-? . Remarkably, the electromechanical effect is attributed to the oxygen vacancies in the lattice and especially to the O-Ce-Vo complexes interacting with external electric fields along the (111) cell orientation [1,4]. Moreover, grain boundaries and disorder affect the electrostriction properties in the material, heavily hindering the electromechanical performances . In this work, we show electrostriction in epitaxial (i.e. grain boundaries-free) CGO thin film in different crystal orientations and thicknesses. Thanks to highly coherent microstructure we can match theoretical principles with experimental data. We find that the electrostriction effect is highly enhanced in textured structures with exceptional values of Q? 1000 m4/C2 for thin films. References: 1. R. Korobko et al., Adv. Mater. 2012, 24, 5857?5861. 2. J. Kuwata et al., Jpn. J. Appl. Phys., 1980, 19, 2099. 3. A. Kabir et al.,Acta Materialia, 2019, 174, 53-60. 4. Y. Li et al., AIP Advances, 2016, 6, 055320.
Authors : J.Spiridonova1, I. Oja Acik1, A. Katerski1, M. Krit?evskaja2, M. Danilson3, M. Krunks1
Affiliations : 1.Laboratory of Thin Films Chemical Technologies, Department of Materials and Environmental Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn; 2. Laboratory of Environmental Technology, Department of Materials and Environmental Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn; 3. Laboratory of Optoelectronic Materials Physics, Department of Materials and Environmental Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn.
Resume : The aim of the current study was to deposit TiO2 thin films by chemical spray pyrolysis method with different titanium isopropoxide (TTIP):acetylacetone (acacH) molar ratios in the solution and determine how acacH increase in starting solution effects the morphology, structure, surface chemical composition and photocatalytic activity of the obtained TiO2 films. TTIP:acacH molar ratio in the spray solution was varied from 1:3 to 1:10. TiO2 films were deposited by the spray pyrolysis method onto the glass substrates at 350°C and heat-treated at 500°C for 1 h. TiO2 films showed the transparency of ca 80% in the visible spectral region, thickness of 400 nm and band gap of ca 3.3 eV irrespective of the TTIP:acacH molar ratio in the spray solution. According to XRD results, TiO2 films consist of anatase crystalline phase with the mean crystallite size in the range of 27-47 nm. Raman results, however, demonstrated that the films deposited from TTIP:acacH molar ratio of 1:5 show the mixture of anatase and rutile phases. Self-cleaning properties of the films were estimated using stearic acid (SA) test. Thin layer of 8.8 mM SA solution was spin coated onto the TiO2 film and the degradation rate of SA as a function of irradiation time was monitored by FTIR. It was found that with an increase in the TTIP:acacH molar ratio from 1:3 to 1:8 the k increases from 0.015 to the 0.314. The increase of SA degradation rate with the rise in acacH amount in the precursor solution will be discussed.
|13:55||Session XV. ZnO and TiO2. Chairs: Su Huai Wei|
Authors : J. Rodrigues*, F. M. Costa, T. Monteiro
Affiliations : Departamento de Física & I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
Resume : Zinc oxide (ZnO) is one of the most versatile semiconductor materials and has been extensively investigated due to its remarkable interest from the technological point of view, namely in areas as optoelectronics, biomedicine, catalysis or photovoltaics. This material has the ability to be grown by a large number of techniques, presenting one of the richest varieties of morphologies, which are known to offer different functional behaviours. Therefore, several methods have been employed to control the production of its micro and nanostructures. In this talk, the development of the laser-assisted flow deposition (LAFD) method for the production of highly crystalline ZnO crystals will be highlighted. Moreover, since the crystals produced by this technique evidence excellent optical quality, optical characterisation was selected as the ideal tool to evaluate their potential applications. In fact, luminescence-based techniques constitute a powerful way to assess the presence of defects that may have a strong influence on the performance of ZnO once applied in photovoltaic cells or as a photocatalytic agent, for instance. Additionally, the photoluminescence (PL) signal can be used as a transduction mechanism in optical-based sensors. This is an excellent method to probe material?s surface/interfaces and the PL signals are usually very sensitive to the chemical/biological species that are placed on the semiconductor?s surface, allowing to identify changes in the target analyte concentrations and providing high sensitivity and selectivity to the devices. Thus, the application of the LAFD-produced structures in the mentioned fields will be also discussed.
Authors : Grym J., ?ernohorský O., Faitová H., Ku?erová ?, Ba?inová N., Yatskiv R, Tiagulskyi S., and Vani? J.
Affiliations : Institute of Photonics and Electronics of the CAS
Resume : ZnO is a direct wide bandgap semiconductor with a broad application potential in UV light-emitting devices and detectors, field-effect transistors, solar cells, piezoelectric nanogenerators, or chemical sensors. Despite a large number of applications, the growth of ZnO from solutions is not well understood and the growth technology mostly relies on empirical results. We investigate the growth of ZnO vertical nanorod arrays on patterned substrates and seed layers in both conventional batch reactors and non-conventional continuous-flow reactors and point out the differences. Unlike the batch reactors, in continuous-flow reactors the solution supersaturation can be accurately controlled, which enables to control the growth rates, the aspect ratio, the incorporation of dopants and impurities, and the density of defects. We further report on fundamental mechanisms of nucleation and growth of the nanorods on the substrates modified by focused ion beam (FIB). Thanks to FIB processing we are able to control the nucleation and positioning of the nanorods. This method enables the nucleation to be uniform even on substrates whose morphology is originally non-uniform. Representative examples of substrates with non-uniform morphology are GaN epitaxial templates, which are commercially widely used as an alternative of expensive GaN monocrystals. Moreover, we present measurements of electronic transport in a single vertically oriented n-type ZnO nanorod on p-type GaN substrate using a nanoprobe in a scanning electron microscope.
Authors : P. Gaffuri 1 2, E. Appert 1, O. Chaix-Pluchery 1, L. Rapenne 1, E. Sarigiannidou 1, M.Salaün 2, and V. Consonni 1
Affiliations : 1 Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France. 2 Univ. Grenoble Alpes, CNRS, Institut Néel, F-38000 Grenoble, France.
Resume : ZnO nanowires (NWs) have recently been widely used in energy and environment-related devices, including gas sensors, piezoelectric nanogenerators, solar cells and UV LEDs. For those applications, intrinsically n-type ZnO nanostructures have intentionally been n-doped by incorporating metal (III) elements, mainly by vapour phase deposition techniques. However, controlling the doping during the growth of ZnO NWs by solution deposition techniques is still a major issue. Here we show that the doping of ZnO NWs, mainly with gallium, can be achieved by the low-cost, low-temperature, and easily implemented chemical bath deposition technique. Gallium nitrate and ammonia are added in various concentrations to the standard precursors , to tune not only the crystal structure of ZnO NWs and hence their morphology, but also the gallium incorporation. The formation mechanisms are thoroughly investigated and supported by thermodynamic simulations: the doping only occurs if the pH of the solution favours the formation of charged gallium hydroxide complexes. This further emphasizes the electrostatic origin of doping mechanisms in aqueous media . The incorporation of gallium is eventually investigated by energy dispersive x-ray spectroscopy using scanning TEM. Furthermore, temperature-dependent Raman spectroscopy shows the occurrence of characteristic additional modes, revealing either the doping of ZnO NWs, or the formation of compensating defects. These findings show a simple, thorough way to control the doping of ZnO NWs, which opens the way for their more efficient integration into nanoscale devices.  R. Parize et al., The Journal of Physical Chemistry C 120, 5242 (2016)  C. Verrier et al., Inorganic Chemistry 56, 3573 (2017)
Authors : M. O. Liedke (1), M. Butterling (1), A. Quintana (2), E. Menéndez (2), E. Hirschmann (1), A. G. Attallah (1), V. Sireus (2), J. Nogués (3,4), J. Sort (2,4), A. Wagner (1)
Affiliations : (1) Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany. (2) Departament de Física, Universitat Autònoma de Barcelona, Cerdanyola del Valle?s, Spain. (3) Catalan Institute of Nanoscience and Nanotechnology (ICN2), Barcelona, Spain. (4) Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
Resume : Modern magneto-electronic devices are ultimately controlled by electric currents, inherently involving a significant energy loss due to heat dissipation. Substituting electric currents by electric fields, where a voltage-induced ionic motion (magneto-ionics) is utilized for the control of magnetism is expected to provide ultra-low power consumption and could be crucial for energy-efficient applications. By means of positron annihilation spectroscopy and magnetometry techniques we have investigated the electrolyte-gated and defect-mediated oxygen and cobalt ions migration in paramagnetic Co3O4, which allows for voltage-controlled ON-OFF room temperature ferromagnetism . Applying a negative voltage reduces Co3O4 to Co (ferromagnetism; ON) and results in a graded material including Co- and O-rich regions. Subsequently, a positive bias reverses the process oxidizing Co back to Co3O4 (paramagnetism; OFF). We show, that this gate-induced O and Co transport is driven by complex vacancies (clusters consisting of both cobalt and oxygen vacancies). Moreover, the O transport is in addition assisted by grain boundaries, which may act as diffusion channels and allow for an exceedingly large incorporation of oxygen. The steady states as a function of bias as well as kinetics of defect-assisted ion migration will be discussed in detail.  A. Quintana, E. Mene?ndez, M.O. Liedke, M. Butterling, A. Wagner, et al. ACS Nano 12, 10291 (2018)
Authors : N. Alhelou1, L. Khomenkova2, C. Frilay2, C. Labbé2, J. Cardin2, F. Gourbilleau2, E. Talbot1
Affiliations : 1GPM, Normandie Univ, UNIROUEN, INSA Rouen, CNRS, Avenue de l?Université BP 12, 76801 Saint Etienne du Rouvray, France 2CIMAP, Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, 6 Boulevard Maréchal Juin 14050 Caen Cedex 4, France
Resume : For several years, the field of physics has witnessed a huge development in the methods proposed to enhance the efficiency of solar cells. The spectral response of a photovoltaic cell doesn?t match with the solar emission spectrum because of the limited absorption of silicon, the main constituent of the active layer. One of the prominent research areas of materials for photovoltaics deals with photonic conversion by optimizing the solar spectrum absorption. In this work, we focus on the feasibility of rare-earth doped oxide matrix (Er3+ in Al2O3) to be an efficient media for up-conversion. Owing to the capability of Er3+ ions to combine two or more lower energy photons into one high-energy photon, they are being considered for the enhancement of the ef?ciency of the solar cells. It has been demonstrated that the spatial distribution as well as the nanostructuring control and the concentration of the active ions have been shown to affect the energy-transfer probability in the Er-doped material. For that reason, we have investigated, using Atom Probe Tomography, the 3D spatial distribution of Er atoms in Al2O3 matrix grown by ALD process. The nanostructure will be discussed and compared to optical properties.
|15:55||Session XVI. Oxide-based bulk and nanomaterials. Chairs: Jan Grym and Martynas Lelis|
Authors : Marco Sarcletti , Dustin Vivod , Tobias Luchs , Luis Portilla , Baolin Zhao , Andreas Hirsch , Dirk Zahn , and Marcus Halik 
Affiliations :  Organic Materials & Devices, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Interdisciplinary Center for Nanostructured films (IZNF), Cauerstr. 3, 91058 Erlangen, Germany;  Computer Chemistry Center & Chair of Theoretical Chemistry, FAU, Nägelsbachstr. 25, 91052 Erlangen, Germany;  Institute of Organic Chemistry II, FAU, Nikolaus-Fiebiger-Str. 10, 91054 Erlangen, Germany.
Resume : Surface waters are steadily contaminated with hydrocarbons (HC) due to minor incidents during production, transportation, and handling of petroleum and its products as well as by major disasters like the Deepwater Horizon explosion. To date, sufficient methods for the economically efficient and ? in particular ? thorough remediation of these pollutants from water are missing. We developed a sustainable alternative to SotA oil spill response agents based on alkylphosphonic acid (PA) functionalized magnetite nanoparticles (NP). That functionalization switches NP from hydrophilic to hydrophobic/oleophilic. This oleophilicity combined with the large specific surface area, eventuates in highly selective and efficient adsorption of HC on the NP surface. The superparamagnetic nature, allows for easy extraction of oil-soaked NP by an external magnetic field. We demonstrated the efficient extraction of different crude oils and organic solvents from the water surface under various conditions. Furthermore, we confirmed the excellent re-usability without significant degradation of the developed sorbent material over several cycles, which is attributed to the strong grafting of the PA on metal oxides and its excellent stability. In addition to the efficient adsorption of surface contaminations, we are able to extract different pollutants from the water column by minor adjustments in the sorbent material.  doi.org/10.1002/adfm.201805742
Authors : M. Selvaraj, P. Vajeeston, J. Mayandi and V. Venkatachalapathy
Affiliations : Department of Physics, R.D. Govt. Arts College, Tamilnadu, Sivaganga - 630561, India Department of Materials Science, Madurai Kamaraj University, Tamilnadu, Madurai- 625 021, India; Department of Chemistry/Centre for Materials Science and Nanotechnology, University of Oslo, P.O Box 1126 Blindern, NO-0318 Oslo, Norway; Department of Materials Science, Madurai Kamaraj University, Tamilnadu, Madurai- 625 021, India. Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O Box 1048 Blindern, NO-0316 Oslo, Norway; Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O Box 1048 Blindern, NO-0316 Oslo, Norway Department of Materials Science, National Research Nuclear University ?MEPhI?, 31 Kashirskoe sh, Moscow, Russian Federation
Resume : Two low-cost chemical methods of sol?gel and hydrothermal process have been strategically combined to fabricate barium titanate (BaTiO3) nanopowders. This method was tested for various synthesis temperatures (100 °C to 250 °C) employing barium dichloride (BaCl2) and titanium tetrachloride (TiCl4) as precursors and sodium hydroxide (NaOH) as mineralizer for synthesis of BaTiO3 nanopowders. BaTiO3 nanopowders synthesized at different temperatures demonstrated stabilization of hexagonal, cubic, tetragonal, orthorhombic and rhombohedral phases. The study shows that choosing suitable precursor and optimizing pressure and temperature; different meta-stable phases of BaTiO3 can be synthesized. So far, stabilization of rhombohedral phase at room temperature is not reported. Optical, magnetic and non-linear optical properties of different meta-stable phases of BaTiO3 have been studied. In addition, the band structure, Raman and infrared vibrational modes are computed by density functional theory (DFT). Influence of post-annealing on the thermal stability and properties by different dopants such as tin (Sn(II), Sn(IV)), zinc (Zn(II)), etc on rhombohedral phase BaTiO3 was investigated. For example, increase in wt% of Sn(IV) dopant ion doping retained the rhombohedral phase of BaTiO3, while Sn(II) doping stabilized rhombohedral-orthorhombic-tetragonal phases with increase in doping wt%. Zn(II) doped BaTiO3 demonstrated superior second harmonic generation (SHG) properties.
Authors : G. Bulai (1), V. Trandafir (2), S. A. Irimiciuc (3), C. Focsa (4), S. Gurlui (2)
Affiliations : (1) Integrated Centre for Environmental Science Studies in the North-East Development Region - CERNESIM, ?Al. I. Cuza? University of Iasi, 700506 Iasi, Romania; Phone Number +40745893044 and e-mail firstname.lastname@example.org (2) Faculty of Physics, Alexandru Ioan Cuza University, Iasi, 700506 Iasi, Romania; (3) National Institute for Laser, Plasma and Radiation Physics ? NILPRP, RO-077125 Magurele-Bucharest, Romania; (4) Université de Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers, Atomes et Molécules, CERLA - Centre d?Etudes et de Recherches Lasers et Applications, Lille F-59000, France
Resume : In this study we investigated the influence of rare earth ion doping on the structural, magnetic and optical properties of CoFe2-xRExO4 (x = 0.01; 0.03; 0.05; 0.1; 0.2; 0.3) ferrite thin films obtained by pulsed laser deposition. The monocrystalline (100) Si substrate was placed at a distance of 5 cm in front of the target during the 60 min deposition. The Nd-YAG laser (532 nm) fluence was kept at 5 J/cm2. The X-ray diffraction and Raman spectroscopy results on the bulk materials, which were used as targets during deposition, revealed the formation of residual phases as the concentration of RE dopant was increased. However, the thin films presented diffraction lines and vibrational modes corresponding only to cobalt ferrite. A lower crystallinity of the deposited samples was observed when higher RE concentrations were used. Due to the substitution of Fe by RE elements which possess large ionic radii, the lattice parameter of the thin films presented a monotonous increase. The magnetic response of the nanostructures was correlated to the magnetic moment of the RE dopant and to the structural properties of the films. The optical bandgaps derived from the reflectance spectra presented an increasing trend as the Yb and Dy concentrations were augmented. Considering the high chemical stability of cobalt ferrite, the thin films analyzed in this study can be adequate for sustainable hydrogen production applications.
|16:45||Closing remarks: Smagul Karazhanov|
Fisica de Materiales, Plaza de Ciencias 1, Ciudad Universitaria, 28040 Madrid, Spaincremades@fis.ucm.es
School of Mathematical and Physical Sciences, PO Box 123, Broadway NSW 2007, AustraliaCuong.Ton-That@uts.edu.au
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