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Materials and devices for energy and environment applications


Carbon and materials for energy applications

Introduction and scope:

A symposium dedicated to the wide range of materials with a focused application in the field of renewable and sustainable energy, is much needed which can connect the theory and experimental outcome spontaneously. Our symposium will be one such attempt in the field of energy research.

Due to simple covalent bonding, carbon shows vivid properties, which can be manifested into the energy applications through different dimensionality like carbon quantum dots, fullerene, carbon nanotubes, two-dimensional graphene and Diamond. They all have enormous applications in the field of solar cells, catalysis, battery technology and hydrogen storage. The ongoing feedback between the experiment and theory concerning energy harvesting opens up new direction of scientific thrust not only in the carbon based systems, but also materials that are attaining interesting electronic, structural, optical and transport properties in order to be applied for sustainable energy resolution. Materials modelling have become equally important along with the experimental investigation to predict such properties, which can be tuned in for different energy applications in the area mentioned above. This is because the atomistic insight of a material is one of the intuitive reasons behind its different properties and this insight we can derive from electronic structure of different materials.

Our symposium will not only be limited to carbon materials, but also all other novel materials that have attracted the focus of the scientific community in the vast field of energy materials. The applications of such materials will be having a broad view in the area of solar cell, photocatalytic water splitting, battery, hydrogen storage and fuel cells. Scientists doing their research in all the above area will be getting a common platform to showcase their latest findings, that will be attached through a common string named Energy. The symposium will be a mixture of theory and experiments with a strong view of bridging the gap between them. The choice of materials is having a wide range from oxide materials to recently synthesized transition metal di-chalcogenides and dimension-wise they can be in bulk, surface, monolayer phase or in form of hetero-structures and nano-composites.

Hot topics to be covered by the symposium:

  • Carbon materials of different dimensionalities – present and next generation
  • Application of Diamond in Energy Research
  • Oxide materials and their application in energy research
  • Two-dimensional materials for energy production and storage
  • Perovskite based materials for solar cell
  • Photocatalytic materials for hydrogen production
  • Novel materials for enhanced battery performance
  • Heterostructured nano-materials and nano-composites

List of confirmed invited speakers:

  • Chris G. Van de Walle, University of California, Santa Barbara, USA
  • Davide Barreca, Padova University, Italy
  • Graig Fisher, Nanostructures Research Laboratory, Japan Fine Ceramics Center, Japan
  • Martin Wilkening, Graz University of Technology, Austria
  • Shulei Chou, University of Wollongong, Australia
  • Kisuk Kang,  Seoul National University, Seoul, Korea
  • Seokwoo Jeon, Korea Advanced Institute of Science and Technology, Korea
  • Yong-Mook Kang,  Dongguk University, Korea
  • Maurizia Palummo, University Tor Vergata Rome, Italy
  • Priya Vashishta , University of Southern California, Los Angeles, USA
  • Hari Srikanth, University of South Florida, Tampa, USA
  • Manickam Minakshi, Murdoch University, Murdoch, Australia
  • T.W. Kang,  Dongguk University,Seoul, Korea
  • Hideyuki Kamisaka, University of Tokyo,  Japan
  • Prakash C. Jha, Central University of Gujarat, Gandhinagar, India
  • Yeon Sik Jung, KAIST, South Korea
  • Hyun Suk Jung, Sungkyunkwan University, South Korea
  • Brunauer G. Christoph, Vienna University of Technology, Austria
  • Soo Young Kim, Chung Ang University, South Korea
  • Ho Won Jang, Seoul National University, South Korea
  • Ladislav Kavan, J. Heyrovsky Institute of Physical Chemistry, Czech Republic
  • Yang Yang Li, City University of Hong Kong, Hong Kong
  • Anja Bieberle-Hütter, DIFFER, The Netherlands
  • Urszula Narkiewicz,West Pomeranian University of Technology, Poland
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Authors : Kevin Sivula
Affiliations : EPFL

Resume : High-efficiency direct solar-to-fuel energy conversion can be achieved using a photoelectrochemical (PEC) device consisting of an n-type photoanode in tandem with a p-type photocathode. However, the development of robust and inexpensive photoelectrodes are needed to make PEC devices economically viable. In this presentation our laboratory’s progress in the development new materials for economically-prepared, high performance photoelectrodes will be discussed along with the application toward overall PEC water splitting tandem cells for H2 production. Specifically, this talk will focus on the application of π-conjugated organic semiconductors. In our recent work [1] we demonstrate a π-conjugated organic semiconductor for the sustained direct solar water oxidation reaction (no evidence of semiconductor oxidation was found over testing time on the order of hours). Aspects of catalysis and charge-carrier separation/transport are discussed. [1] Bornoz, P.; Prevot, M. S.; Yu, X.; Guijarro, N.; Sivula, K., J. Am. Chem. Soc. 2015, 137, 15338-15341.

Authors : Davide Barreca,1 Giorgio Carraro,2 Alberto Gasparotto,2 Chiara Maccato2
Affiliations : 1 CNR-ICMATE and INSTM, Department of Chemistry, Padova University, 35131 Padova, Italy. 2 Department of Chemistry, Padova University and INSTM, 35131 Padova, Italy.

Resume : Hydrogen production by photoelectrochemical H2O splitting activated by sunlight is a strategic option to produce carbon-neutral energy from abundant natural resources. Among the possible photoanode materials, hematite (α-Fe2O3) has been under intense scrutiny for its low cost, favorable energy gap (2.1 eV) and high stability. Nevertheless, its photoresponse is detrimentally affected by various factors, such as the very short excited state lifetimes and poor reaction kinetics. This talk will present recent advances achieved by our group in the improvement of α-Fe2O3-based photoanode performances. Tailoring of the system nano-organization, structure and composition will be discussed in relation to the following case studies: • single-phase α-Fe2O3 photoanodes, with regard to the influence of ex-situ treatment, deposit thickness and aggregate size on functional properties;1 • Pt/α-Fe2O3 nanocomposites, highlighting the interplay between Pt redox state and Fe2O3 morphology on the composite photoactivity;2 • α-Fe2O3-TiO2 nano-heterostructures with high PEC performances even in solar-activated seawater oxidation, exploiting an improved charge separation promoted by Fe2O3/TiO2 junctions.3 These encouraging results open a new avenue in the fabrication of nano-devices for energy generation from abundant and renewable natural resources. 1 ACS Appl. Mater. Interfaces, 2015, 7, 8667. 2 Phys. Chem. Chem. Phys., 2015, 17, 12899. 3 Adv. Mater. Interfaces, 2015, 2, 1500313.

Authors : Anja Bieberle-Hütter
Affiliations : Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven, the Netherlands

Resume : Photo-electrochemical (PEC) water splitting for the production of fuel is still in its infancy due to limited understanding of the solid electrode - liquid electrolyte interface [1]. From the experimental side, this interface is difficult to approach due to the liquid phase which requires sealing and due to limited access by in-situ and operando techniques; from the simulation side, the high degree of freedom of the water molecules at the interface as well as first principles software mainly designed for solid-gas interfaces make the studies complex. In our presentation, we will focus on the hematite (Fe2O3) PEC interface both experimentally as well as theoretically. We will first review experimental [e.g. 2] and theoretical [3] studies of the interface and discuss the challenges. We will then focus on the characterization of several well-defined hematite interfaces prepared by sputtering and post-deposition treatment, such as high ion flux plasma. We will show how the micro-/nanostructure of the films impacts the PEC properties. Finally, we will present simulation results [4] from our multi-scale modeling & simulation approach focusing on improved analysis of experimental PEC data. 1 van de Krol, Grätzel, Photoelectrochemical Hydrogen Production (Springer, 2012). 2 Klahr et al., Energy Environ. Sci. 5 (2012) 7626. 3 Zhang, Bieberle-Hütter, ChemSusChem Minireview, 10.1002/cssc.201600214 (2016). 4 Zhang, Klaver, van Santen, van de Sanden, Bieberle-Hütter, in preparation.

Authors : Priya Vashishta Rajiv K. Kalia, Aiichiro Nakano, Ying Li, Ken-ichi Nomura, Adarsh Shekhar, Fuyuki Shimojo, Kohei Shimamura,
Affiliations : Collaboratory for Advanced Computing and Simulations, Department of Chemical Engineering & Materials Science, Department of Physics & Astronomy, and Department of Computer Science, University of Southern California, Los Angeles, CA 90089-0242, USA Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, IL 60439, USA Department of Physics, Kumamoto University, Kumamoto 860-8555, Japan

Resume : Billion atom molecular dynamics simulations are used to investigate critical issues in the area of structural and dynamical correlations, and reactive processes in nanostructured materials under extreme conditions. Cavitation bubbles readily occur in fluids subjected to rapid changes in pressure. We use billion-atom reactive molecular dynamics simulations on a 163,840-processor BlueGene/P supercomputer to investigate chemical and mechanical damages caused by shock-induced collapse of nanobubbles in water near silica surface. Collapse of an empty nanobubble generates high-speed nanojet, resulting in the formation of a pit on the surface. The gas-filled bubbles undergo partial collapse and consequently the damage on the silica surface is mitigated. Quantum molecular dynamics (QMD) simulations are performed on 786,432-processor Blue Gene/Q to study on-demand production of hydrogen gas from water using Al nanoclusters. QMD simulations reveal rapid hydrogen production from water by an Al nanocluster. We find a low activation-barrier mechanism, in which a pair of Lewis acid and base sites on the Aln surface preferentially catalyzes hydrogen production. I will also discuss on-demand production of hydrogen gas from water using and LiAl alloy particles. Oxidation dynamics in self-healing ceramic materials is also discussed.

Authors : Chris G. Van de Walle
Affiliations : Materials Department, University of California, Santa Barbara, California, USA

Resume : The wurtzite-structure nitride semiconductors, AlN, GaN, and InN, are the key materials for energy-efficient technologies such as solid-state lighting and power electronics. BN prefers the hexagonal or zinc-blende forms; however, alloys between BN and AlN or GaN can be stabilized in the wurtzite structure. The large lattice mismatch between the constituent materials affects the stability and electronic structure of BAlN and BGaN alloys. We also determine band alignments and polarization properties [1]. Additionally, we study point defects as well as intentional and unintentional impurities. For hydrogen, we report surprising behavior, namely an unusual stability of the neutral charge state, also found in diamond [2]. Consequences for applications are discussed. Work performed in collaboration with C. E. Dreyer, A. Janotti, J. Lyons, L. Weston, and J. Shen, and supported by LEAST and NSF. [1] C. “Band alignments and polarization properties of BN polymorphs”, C. E. Dreyer, J. L. Lyons, A. Janotti, and C. G. Van de Walle, Appl. Phys. Express 7, 031001 (2014). [2] J. L. Lyons and C. G. Van de Walle, J. Phys.: Condens. Matter 28, 06LT01 (2016).

Authors : Manickam Minakshi
Affiliations : Murdoch University, Perth, WA 6150, Australia

Resume : Energy storage in rechargeable batteries and supercapacitors is the most promising prospect for ensuring consistent energy supply [1-2] therefore allowing greater penetration of renewable energy into the electricity grid. Energy storage capability also has obvious benefits in terms of greenhouse emissions. Issues such as the environment, the rapid increase in fossil fuel prices, and the increased deployment of renewable energy sources, provide a greater need for the development of electrochemical energy storage, especially for large-scale applications. Thus, materials research and computational modelling play a key role in making further progress in the field of energy storage. Energy storage devices based on sodium have been considered as an alternative to traditional lithium based systems because of the natural abundance, cost effectiveness and low environmental impact of sodium. Oxides and lithium transition metal phosphates have been researched for over two decades and many technologies based on them exist. Much less work has been done on investigating the use of sodium phosphates for energy storage. The structural and electrochemical properties of phosphate materials such as NaNiPO4, NaMnPO4, NaCoPO4 and NaNi1/3Mn1/3Co1/3PO4 will be discussed at the conference. Among the materials studied, the NaNiPO4 vs. activated carbon in 2 M NaOH exhibit the maximum specific capacitance of 125 F g-1 at 1 A g-1 showing excellent cycling stability with retention of 99 % capacity up to 2000 cycles. Sodium transition metal phosphate has served as an active electrode material for an energy storage device [3-4]. The development of sodium transition metal phosphate with special emphasis on structural changes and novel synthetic approach can underpin technological advancements in small renewable energy harvesting and power generation technologies. The characteristics of the fabricated device such as improved storage capability, cycling stability, safety and economic life - cycle cost made this an attractive alternative to conventional charge storage devices using more expensive materials. References 1. J. Zhang, J. Jiang, H. Li, and X. S. Zhao, Environ. Sci. 4 (2011) 4009. 2. C. Liu, F. Li, L.-P. Ma, M.-M. Cheng, Adv. Mater. 22 (2010) E28. 3. M. Minakshi, D. Meyrick and D. Appadoo, Energy & Fuels 27 (2013) 3516. 4. M. Minakshi, T. Watcharatharapong, S. Chakraborty, R. Ahuja, S. Duraisamy, P. T. Rao and N. Munichandraiah, Dalton Trans. 44 (2015) 20108.

Authors : Isis Maqueira-Albo, Francesca Scuratti, Giorgio Dell’Erba, Mario Caironi
Affiliations : Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Pascoli 70/3 – 20133 – Milano (Italy)

Resume : Single walled carbon nanotubes (SWNTs) are promising materials for electronic applications. Semiconducting SWNTs offer the possibilities to considerable increase the performance of field-effect transistors (FETs). However, several factors in the sample preparation interfere in gaining a complete picture of the charge carrier transport. To further push the adoption of this kind of devices in everyday life applications, high-throughput dispersion and fabrication methods must be adopted. In this work, we highlight how the process for chirality selection and dispersion of SWNT operated by polymer wrapping with poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(6,6’-{2,2’-bipyridine})] in common organic solvents may be used for the realization of printed FETs. The printing process was performed in ambient air and at room temperature. In order to obtain a sufficiently well interconnected network of SWNTs multiple subsequent layers were printed resulting in a surface coverage of ≈75%. The devices exhibit ambipolarity, with a slight prevalence of the n-type behaviour. For both, electron and hole accumulations, in linear regime 106 on-off ratios can be observed, with mobilities around 0,3 cm2V-1s-1 for both carrier types. In saturation regime mobility values up to 0,8 cm2V-1s-1 for electrons and 0,65 cm2V-1s-1 for holes are reached. The study also highlights the effects of different solvents on the SWNT network formation and FET performances with best results with those solvents that tend to form polymer pre-aggregates in the printed solution (i.e. Mesitylene, o-Xylene).

Authors : Maurizia Palummo [1], Marco Bernardi [2], Giancarlo Cicero [3], Jeffrey C. Grossman [4]
Affiliations : [1] ETSF, Dept. of Physics University of Rome “Tor Vergata” Italy and INFN, Laboratori Nazionali di Frascati, Via E. Fermi 40, I-00044 Frascati, Italy [2] Department of Applied Physics and Material Science California Institute of Technology 1200 East California Boulevard Pasadena USA [3]Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129, Italy [4] Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States

Resume : In the last years two-dimensional transition metal dichalcogenides (TMDs) have received a large amount of attention because of their peculiar and versatile physical properties [1]. The selection of transition metal and chalcogen, the high impact of strain, defects and dopants, the possibility of Van Der Waals (vdW) stacking of different mono-layers, joined to the weak dielectric screening and the strong light-matter interaction, offer a unique opportunity to engineering the electronic and optical properties for next generation ultra-thin opto-electronic devices [1,2]. In this speech I will review the current status of fundamental knowledge of the very promising electronic and opto-electronic properties of 2D-TMDs. I will show how ab-initio DFT and post-DFT calculations, based on the Many-Body Perturbation Theory (MBPT), provide a very useful scheme to explain: i) the extraordinary sunlight absorption ii) the giant electronic band-gaps renormalization iii) the presence of strongly bound but spatially delocalized excitons iv) the large variety of the excitons radiative lifetimes observed [3] and also v) the influence of the electron-phonon interaction play on the electronic and optical spectra [4] Finally the role of doping and molecular functionalization to tune all these properties will be also discussed [5]. [1] M. Bernardi, C. Ataca, M. Palummo, J. C. Grossman Journal of Nanophotonics (2016) [2] M. Bernardi, M. Palummo, J. C. Grossman, Nano Letters (2013), 13( 8), 3664 [3] M.Palummo, M. Bernardi, J.C. Grossman Nano Letters (2015) 15 (5), [4] A. Molina-Sánchez, M Palummo, A Marini, L Wirtz Physical Review B 93 (15), 155435 [5] G. Cicero, M. Palummo, J.C. Grossman in preparation

Authors : Hari Srikanth
Affiliations : Department of Physics, University of South Florida, Tampa, Florida, USA

Resume : Current research efforts in magnetic refrigeration are focused on materials that possess both large magnetocaloric effect (MCE) and large refrigerant capacity (RC). Since a magnetic material is the working body of a cooling system, it must have a large heat transfer area to provide high heat exchange efficiency. In this context, exploring magnetocaloric materials on the nanoscale and microscale can be of practical importance. Relative to their bulk counterparts, nanomaterials possess enhanced surface area, thus providing better heat transfer. Laminated high aspect ratio microwires have also been predicted to be ideal candidates from this perspective. The general trend is that saturation magnetization reduces in nanomaterials thus reducing the MCE. However in multiphase materials and composites this trend can be reversed and large MCE and RC can simultaneously be stabilized. In this talk I will feature three different strategies to demonstrate this point. We show that in mixed phase manganite nanoparticles a strong enhancement of MCE and RC and a strong reduction of thermal and field hysteresis losses can be achieved. Composites of thermoelectric clathrates Eu-Ga-Ge mixed with EuO exhibit desirable magnetocaloric properties in the liquid nitrogen range and open up the exciting possibility of dual functional thermoelectric-magnetocaloric refrigeration. Finally we show that laminated microwires of amorphous Gd-based alloys are excellent candidates with RC values than that of bulk Gd. Overall we demonstrate that tailored nanocomposites are promising materials for the realization of practical, energy-efficient magnetic refrigerators.

Authors : Mayuko Oka, Hideyuki Kamisaka, Tomoteru Fukumura, Tetsuya Hasegawa
Affiliations : The University of Tokyo; The University of Tokyo; Tohoku University; The University of Tokyo, Kanawaga Academy of Science and Technology

Resume : Oxygen ion conductors are attracting much attention as electrolytes for solid oxide fuel cells. Recently, an enormously high ionic conduction has been reported for YSZ/SrTiO3 heterostructure[1]. Several theoretical studies have investigated the origin of the increase in ionic conduction in terms of strain imposed at the interface [2]. We investigated the conduction of oxygen ions in doped ZrO2 systems under the epitaxial strain conducting ab initio molecular dynamics (MD) calculations [3]. The most stable structure of ZrO2 under the strain was identified by DFPT-based phonon calculations. Combining a series of simulations with various vacancy/dopant concentrations, we discussed three factors for the ionic conduction: lattice strain, oxygen vacancies, and dopants. Formation of the new oxygen sublattice was observed under the strain, and its deformation by oxygen vacancies played an important role for increasing the conductivity. In this presentation, we also introduce our recent study of N/F-doped ZrO2 under epitaxial strain. The effect of N/F doping was analyzed not only from the magnitude of ionic conduction but also from the dynamical motion of anion sub-lattice. We observed flipping motion of zigzag structure of oxygen sublattice, and the motion was affected by oxygen vacancies or anion dopants. Prominent enhancement of the conductivity was found for the N/F-doping under certain concentration of the oxygen vacancies. References [1] J. Garcia-Barriocanal et al., Science, 321 (2008) 676. [2] T. J. Pennycook et al., Phys. Rev. Lett. 104 (2010) 115901. [3] M. Oka et al., Phys. Chem. Chem. Phys. 17 (2015) 29057. * The computations were performed using Research Center for Computational Science, Okazaki, Japan.

Affiliations : 1Université de Lyon, IRCELyon, CNRS, UMR 5256, F-69626 Villeurbanne, France 2Université de Lyon, INL, CNRS, UMR 5270, INSA Lyon, F-69621 Villeurbanne, France 3 Lotus Synthesis SAS, F-69100 Villeurbanne, France

Resume : An overwhelming economic improvement for white LED and photovoltaic (PV) markets is based on the use of lanthanide-free phosphors that are supposed to convert UV light into visible one, thanks to down-conversion (DS) process. ZnO nanoparticles (NPs) have aroused an increasing interest since they possess a variety of intrinsic defects that provide light emission in the visible range without the introduction of any additional impurity. However, high photoluminescent quantum yield (PLQY), stable green/yellow emission and easy scale–up process are expected for industrial applications. Li-doping and polymer surface modifications of ZnO nanoparticles are mainly used in order to reach high PLQY (>30%) but PLQY decay over few days, uses of sophisticated polymers or multi-step reactions are the main issues for industrial implementation. In collaboration with the company Lotus Synthesis, we developped and patented an industry-capable and cost effective chemical solution process to get unique mesospheric self-assembly hybrid ZnO system with intense (PLQY = 40-75%) and stable visible emissions. We also demonstrate that the use of mixture of commercial polyacrylic acid-based polymers can provide large scale amounts of ZnO NPs clear water suspensions that can be dried and dispersed again in water without compromising the functional performance (e.g. transparency and PLQY) of the final DS layer. We will then address the effects of the ZnO NPs surface functionalization - such as nature, molecular weight, concentration, ratio of the PAA-based polymers and self-assembly process- on the enhancement of the efficiency of DS hybrid materials for LED and PV markets.

Authors : Hadi Sedaghat Pisheh (a); Negar Gheshlaghi (a); Hilmi Ünlü (a,b,*)
Affiliations : (a) Nanscience and Nanoengineering Programme, Institute of Science and Technology İstanbul Technical University, Maslak Istanbul 34469 TURKEY (b) Department of Physics, Faculty of Science and Letters İstanbul Technical University, Maslak Istanbul 34469 TURKEY

Resume : Colloidal semiconductor nanocrystals (NCs), also termed quantum dots (QDs), are composed of a core surrounded by different band gap material of its kind. With respect to core NCs, core/shell systems exhibit generally enhanced stability against photodegradation. So an important strategy to improve NCs’ surface passivation is their overgrowth with a shell of a second or third semiconductor, resulting in core/shell (CS) or core/shell/shell (CSS) heterostructured nanocrystals. Furthermore, by the appropriate choice of the core and shell materials, it is possible to tune the emission wavelength in a larger spectral window than with both materials alone. In this work we report a synthetic route to prepare ZnSe/Zn(Cd)S/Cd(Zn)S and CdSe/Zn(Cd)S/Cd(Zn)S Core/Shell/Shell heterostructured NCs. The synthesized nanocrystals were characterized by using high resolution TEM, x-ray diffraction (XRD) for structural properties and UV absorption and fluorescence techniques for optical properties. An ‘‘inverse’’ quantum dot quantim well (QDQW) structure has been realized with the synthesis of CdSe/ZnS/CdS and ZnSe/ZnS/CdS NCs, as here the larger-bandgap material is embedded between the lower-bandgap ones. In the case of CdSe/CdS/ZnS, CdS as a strain-reducing intermediate shell sandwiched between the core NC and the outer shell. The interest of such structures lies in the combination of low strain, provided by the intermediate layer (CdS) serving as a ‘‘lattice adapter’’ and the outer shell (ZnS) which assures efficient passivation and charge-carrier confinement. The effects of lattice mismatch induced interface strain on the first exciton energy, capped core diameter and conduction and valence band energies of the quantum dots investigated. The induced interface strain from lattice mismatch between core and shell(multishell) calculated from continuum elastic theory and included in effective mass aproximation (EMA) to calculate corresponding capped core diameter. The results compared with bare core images from TEM to evaluate squeeze (stretch) amount in core size after compressive (tensile) shell deposition. (*) Corersponding Author.

Authors : Wei Li, Dehua Xiong, Lifeng Liu*
Affiliations : International Iberian Nanotechnology Laboratory

Resume : Electrochemical water splitting is a clean and sustainable way to produce hydrogen fuel. In order to replace the costly Pt electrocatalyst in the electrolyzer, great efforts are devoted to the search for non-precious, earth-abundant catalysts. Herein, high-density cocoon-like MoS2 nanostructures have been fabricated by thermal oxidation of a metallic Mo foil, followed by a simple sulfurization process under hydrothermal conditions.[1] The MoS2 layer thickness is determined by that of the pre-formed oxide layer on Mo foils, which can be readily tuned by thermal oxidation duration. The MoS2 cocoons consist of many vertically aligned ultrathin nanosheets with preferentially exposed edges, and the MoS¬2 cocoon layer is intimately bonded to the underneath Mo substrate for samples having a small layer thickness. Electrochemical studies demonstrate that all MoS2-Mo cathodes exhibit high electrocatalytic activities, small Tafel slopes and good long-term stability for hydrogen evolution reaction (HER). The outstanding HER performance can be attributed to the existence of abundant electrocatalytically active edge sites and structural defects, and to the intimate electrical contact between MoS2 and metallic Mo and the bind-free nature of the electrode, which facilitate electron transfer. Given the high electrocatalytic performance and the easy fabrication procedure, Mo supported cocoon-like MoS2 holds substantial promise to substitute platinum for use to catalyze HER in water electrolyzers. Reference [1] Wei Li, Xiaoguang Wang, Dehua Xiong and Lifeng Liu, International Journal of Hydrogen Energy, 2016, doi:10.1016/j.ijhydene.2016.03.209.

Authors : Tae Won Kang1, Gennady N. Panin1, Wei Wang2, R. Ahuja3
Affiliations : 1Quantum-functional Semiconductor Research Center and Department of Physics, Dongguk University; 2Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology Wuhan University;3Department of Physics and Astronomy, Uppsala University

Resume : MoS2 nanosphere memristor with lateral gold electrodes was found to show a photoresistive switching. The novel device can be controlled by a charge polarization of the nanospheres and switched the resistance by an electric field in the dark and under white light illumination. The charge polarization allows to change the switching voltage of the photomemristor, providing the multi-level operation. The nanosphere structure polarized at voltage of 6V shows the sharp resistive switching under white light excitation from high resistance state (HRSL6) to low resistance state (LRSL6) with on/off ratio of 10 and the smooth resistive switching in the dark. The device polarized at the voltage of 3V shows the smooth resistive switching under white light and in the dark. Analysis of the electrical conductivity in the resistive states indicates that charging and polarization the nanospheres modulated by light could form and interrupt highly conductive filaments to switch the photoresistance. MoS2 photomemristor shows great potential as a new multifunctional device, obtained by simple solution-processing techniques.

Authors : Georgios A. Tritsaris, Sharmila N. Shirodkar, Efthimios Kaxiras, Paul Cazeaux, Mitchell Luskin, Petr Plecháč, Eric Cancès
Affiliations : Georgios A. Tritsaris; Sharmila N. Shirodkar; Efthimios Kaxiras. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA. Paul Cazeaux; Mitchell Luskin. School of Mathematics, University of Minnesota, Minneapolis, Minnesota 55455, USA. Petr Plecháč. Department of Mathematical Sciences, University of Delaware, Newark, Delaware 19716, USA. Eric Cancès. Université Paris Est, Ecole des Ponts and INRIA, 77455 Marne-la-Vallée, France.

Resume : The physics of two-dimensional systems, composed of one or several layers that have thickness of a single atom or a few atoms, is becoming ever more interesting as the realization of such nanostructures with essentially any desirable combination of materials are within grasp of experiment [1]. Atomistic materials modeling and ab initio simulation can accelerate the discovery of novel two-dimensional materials with tailored optoelectronic properties but a big challenge in this direction is the modeling of twisted assemblies or assemblies comprising layers with different in-plane lattice constants, for which naive structural models would involve exceedingly large supercells. Here, we present a simple framework for the study of the electronic properties of weakly coupled, atom-thick structures [2]. Within this framework, we calculate the electronic structure of prototypical commensurate and twisted bilayers of graphene (Gr) and hexagonal boron nitride (h-BN), and of a Gr/h-BN heterostructure, which we compare with reference full-scale density functional theory calculations. We find that for relatively large twist in the twisted assemblies, the perturbation of electronic states near the Fermi level is negligible. The capabilities of our method open the path for fast computational screening of layered assemblies of any composition or relative orientation for targeted design of advanced materials. [1] Geim A. K. and Grigorieva I. V. van der Waals heterostructures. Nature 499, 419 (2013).; [2] Tritsaris G. A., Shirodkar S. N., Kaxiras E., Cazeaux P., Luskin M., Plecháč P. and Cancès E. J. Mater. Res. 31, 959 (2016).

Authors : Siyu Yu, Hao Zhuang, Nianjun Yang*, Soumen Mandal, Oliver A. Williams and Xin Jiang*
Affiliations : Institute of Materials Engineering, University of Siegen, 57076 Siegen, Germany School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, UK

Resume : Heavily boron-doped diamond is quite promising for electrochemical capacitor applications due to its widest electrochemical potential window in all media, its longest life-time under different conditions, many easy and available approaches to produce various diamond nanostructures with high surface areas. Therefore in the first part of this presentation, the recent progress and achievements using boron-doped diamond and well as its nanostructures (e.g., nanowires, networks, etc.) for the construction of electric double layer capacitors (EDLCs) will be shown. In the second part, diamond based pseudosupercapacitors will be presented. Diamond pseudosupercapacitor constructed using MnO2 on the electrode surface will be introduced. The construction of diamond pseudosupercapacitor by use of diamond networks and redox electrolyte in the solutions will be highlighted. The performance of these capacitors (e.g., capacitance, retention of the capacitance, power and energy density, etc.) will be discussed and in details compared with those shown in literature as well.

Authors : Ji Hun Choi, Himchan Oh, Seong Hyun Kim, Su-Jae Lee, Sooji Nam
Affiliations : Electronics and Telecommunications Research Institute (ETRI)

Resume : Thermoelectric (TE) materials what can directly convert waste heat into electrical power have been broadly studied with target to the high efficiency. The most efficient TE materials are known as inorganic semiconductors, bismuth telluride, for example. Despite of its high efficiency, inorganic semiconductors have a lot of drawbacks which include high cost, toxicity, and shortage of resources. This is because many people pay big attention to organic-based TE materials like polymer. Organic-based TE materials can provide advantages such as low cost, solution-processability, ease of handling, abundance of resources, and possibility of mass production. Most of previous studies on the organic-based TE system adopt polymer thin film including conducting materials for both low thermal conductivity and reasonable electrical conductivity. In this research, we present porous organic-based TE system using electrospinning process for obtaining further lower thermal conductivity. The bunch of air holes could reduce thermal conductivity of the TE system compared to the film type organic-based TE system, and the metal nanoparticles (MN) in the polymer guarantee the sufficient electrical conductivity. This structural changes show enhanced TE system efficiency as well. Also, 4 types of organic-based TE system have been analyzed: (a) polymer film without MN, (b) porous polymer film without MN, (c) polymer film with MN, (d) porous polymer film with MN.

Authors : Joel Cabañero Jr*, Cyril Marino, Claire Villevieille
Affiliations : Paul Scherrer Institut, Electrochemistry Laboratory, CH-5232 Villigen PSI, Switzerland

Resume : Rechargeable sodium-ion battery is a potential alternative to the widely used Li-ion technology since sodium’s higher abundance compared to lithium would enable the commercialization of a cheaper energy storage system. While an array of inorganic compounds can be chosen as positive electrodes, choosing the right negative electrode remains a challenge as graphite in Li-ion batteries cannot be used in the Na-ion system. Carbonaceous materials are attractive anodes for sodium-ion batteries and their syntheses usually involve pyrolysis of polymeric precursors such as sugar and polyacrylonitrile in an inert atmosphere [1]. However, these polymeric precursors can be substituted by organic waste materials, which present an advantage of further decreasing the overall price of battery production. In this study, we report the use of nut shells from almonds as source of carbonaceous anode material for sodium-ion batteries. Optimization of the synthesis procedure consisted of varying synthesis parameters such as the number of pyrolysis cycles, type and gas flow, synthesis temperature and time. Carbonaceous materials were then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, conductivity and BET surface area measurements. Preliminary results reveal that varying the number of pyrolysis cycles allows the tuning of the carbon’s microstructure which can have a significant impact on their electrochemical performance [2]. Galvanostatic cycling in C/8 rate at room temperature showed that the almond nut shells pyrolysed once have a better specific charge (279 mAh/g) than the shells pyrolysed twice (272 mAh/g). Analysis of the Raman spectra confirmed a lower degree of graphitization for the sample pyrolised once, which explains its slightly improved electrochemical performance. Almond nut shells thus show a great potential as a cheap source of carbonaceous anode material for sodium-ion batteries considering the current state of art [3]. References: [1] E. Irisarri, A. Ponrouch, and M. R. Palacin, "Review-Hard Carbon Negative Electrode Materials for Sodium-Ion Batteries," Journal of the Electrochemical Society, vol. 162, pp. A2476-A2482, 2015. [2] Z. Biao, C. M. Ghimbeu, C. Laberty, C. Vix-Guterl, and J. M. Tarascon, "Correlation Between Microstructure and Na Storage Behavior in Hard Carbon," Advanced Energy Materials, vol. 6, pp. 1501588 (9 pp.)-1501588 (9 pp.), 7 2016. [3] A. Ponrouch, A. R. Goni, and M. R. Palacin, "High capacity hard carbon anodes for sodium ion batteries in additive free electrolyte," Electrochemistry Communications, vol. 27, pp. 85-88, Feb 2013.

Authors : Dong Young Kim, Min Choi, Tae-Ho Yoon
Affiliations : School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST)

Resume : Bacterial cellulose (BC) has received a great attention since it is an environmentally benign beside it is easily prepared by microbial fermentation process. Thus, BC has been studied for wide applications, such as porous carbon materials which can be used for filtration and electrode material for supercapacitors1. Unfortunately, it is not easy to prepare even thickness of BC via microbial fermentation process especially if thick plated is needed. Moreover, BC has to be freeze-fried prior to pyrolysis to make porous structure, which is expensive process. To solve such problems, BC pellicles are shredded and filtered to get BC disc with even thickness2. However, the porosity control of BC is still unsolved problem. In our study, we introduced water soluble polymer to shredded BC prior to filtering, which can burn during the pyrolysis, forming pores and thus expensive freeze-dry is not required. In addition, we also add few-layer-graphene (FLG) with edge-functionalized to enhance the electrical and mechanical property of electrode. The porous carbon structure from BC is characterized by SEM, and BET and conductivity are also measured, together with electrochemical properties

Authors : Atsushi Nitta1, Kazuya Kawahara2, Kazuhiro Takeda3
Affiliations : 1 Department of Electronic Control Engineering, National Institute of Technology, kagoshima College, Kirishima, Japan; 2 Advanced Mechanical and Electronic Systems Engineering, National Institute of Technology, kagoshima College, Kirishima, Japan; 3 Department of Information Engineering, National Institute of Technology, kagoshima College, Kirishima, Japan

Resume : The application of electronics manufacturing technology using printing techniques to flexible devices has recently attracted the attention of many researchers. Organic electroluminescence displays, organic solar cells, and organic transistors using organic materials have been actively studied. In these electronic devices, transparent electrodes, which transmit visible light and possess conductivity, are important components. An indium tin oxide (ITO) thin film is often used as a material for a transparent conductive film; however, because an ITO thin film contains indium, a rare metal, resource depletion and cost increases are concerns. Moreover, an ITO thin film is not suitable for flexible devices because of its fragility to bending stress. Therefore, a flexible transparent conductive film that has characteristics equal to those of an ITO thin film is required. The present study focused on poly(3,4-ethylenedioxythiophene)/ poly(styrenesulfonate) (PEDOT/PSS) as a substitute for ITO. PEDOT/PSS is a conductive polymer possessing high conductivity and transparency. We formed a PEDOT/PSS thin film on a polyethylenenaphthalate film substrate using an ink-jet printer and investigated the relationships among the post-print processing, the surface state of the thin film, and the film’s electrical and optical properties. Consequently, a solvent mixed when a conductive ink was prepared for stable film deposition adversely affected the characteristics of the thin film after printing, and no sufficient conductivity could be obtained. The effects of the removal of the solvent by annealing after film deposition and the change in the surface state of the thin film based on the aggregation of PEDOT/PSS particles on the electrical and optical properties of the thin film were elucidated. The application of a polar solvent after annealing facilitated the arrangement of PEDOT molecules, which promoted surface state homogeneity of the thin film. The surface homogeneity and electrical and optical properties of the thin film were improved by the application method. These results will help improve the manufacture of flexible devices using only ink-jet printing.

Authors : Lisha Yin1 Can Xue2
Affiliations : 1, Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (NanjingTech) 2, School of Materials Science and Engineering, Nanyang Technological University

Resume : Platinum (Pt) has been intensively applied as a cocatalyst since it works efficiently on a variety of semiconductors towards photocatalytic hydrogen generation. However, the rareness and high cost restrict the further application of Pt in large-scale photocatalytic hydrogen generation in the future. In order to reduce the Pt content whereas maintain the excellent performance, Pt was partially substituted by cobalt (Co) and the bimetallic Pt-Co alloy nanoparticles were deposited onto g-C3N4 via solvo-thermal approach. The as-prepared Pt-Co alloy deposited g-C3N4 with atomic ratio of 2.5/1 and loading amount of 1 wt% exhibited a photocatalytic hydrogen generation rate of 4.63 µmol·h-1, 1.6 times of 1 wt% Pt loaded counterpart (2.95 µmol·h-1) under the same conditions. In addition, the synthetic approach was extended to other Pt based bimetallic alloys loaded g-C3N4 composites and Pt2.5M/g-C3N4 (M=Fe, Ni) were prepared. Both Pt2.5Fe/g-C3N4 and Pt2.5Ni/g-C3N4 revealed higher or similar performance in comparison with 1 wt% Pt loaded g-C3N4. The enhancement in photocatalytic activity was further investigated by photoluminescence spectra (PL) and electrochemical impedance spectra (EIS), suggesting the enhanced activity was ascribed to more effective separation of photogenerated electron/hole pairs from g-C3N4 to the Pt2.5Co alloy. Thus, our study demonstrates great potential of Pt based bimetallic alloys as alternative cocatalysts of Pt for photocatalytic hydrogen generation.

Authors : Yuljae Cho, Byung-Sung Kim, Juwon Lee, Jung Inn Sohn, SeungNam Cha, and Jong Min Kim
Affiliations : Yuljae Cho, Byung-Sung Kim, Juwon Lee, Jung Inn Sohn, SeungNam Cha, and Jong Min Kim Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom

Resume : Polyvinylidenefluoride (PVDF)-based polymers that exhibit outstanding ferroelectric and piezoelectric characteristics have been extensively researched for next-generation energy applications due to a set of attractive characteristics, such as flexibility, cost-effectiveness, ease of processing, and environmentally-friendly nature. Their outstanding ferroelectric and piezoelectric properties are resulted from electrical dipoles that tend to form normal to the surface. As a result, the surface morphology and roughness play a key role in inducing stronger ferroelectric field which is the vector sum of the electrical dipoles on the surface. However, it has been reported that conventionally used thermal annealing (TA) tends to form extremely rough surface. This rough surface leads to induce a weak ferroelectric field on the film and end up with poor device performances. In order to attain a high ferroelectric field and consequently improved device performances, the formation of smooth and flat surface is highly required. By applying a solvent annealing (SA) method, it was possible to form a smooth and flat PVDF surface. The surface potential measurement and devices performances revealed that the SA film showed significantly improved performances compared to that of the TA one. Improved surface potential and device performances with the SA film are attributed to higher vector sum of electrical dipoles that were well-aligned on the smooth and flat SA film.

Authors : Angeloclaudio Nale, Flavio Pendolino, Amedeo Maddalena, Paolo Colombo
Affiliations : Department of Industrial Engineering, University of Padova, via Marzolo 9, 35131 Padova, Italy

Resume : Light metal borohydrides are good candidate materials for hydrogen storage but they are limited by their excessive stability. Reduced Graphene Oxide (rGO) was prepared by clean thermal treatment in hydrogen atmosphere from graphene oxide obtained by modified wet chemical synthesis. The effect on different boronhydride of rGO and Single-walled carbon nanohorns (SWNH) have been investigated with thermal programmed desorption volumetric analysis, to test the gas release in presence of the three different carbon materials. It has been observed that rGO and SWNH leads to a lower decomposition temperature and to a different gas-release profile compared to pristine borohydrides and reference mixtures with graphite. rGO shows the most pronounced impact on the gas release performance of different complex borohydride even without metal additives with catalytic properties. The comparison of XRD profiles of decomposed samples shows a different pattern for the samples with rGO compared to samples with graphite for every metal cation, suggesting a different pathway of decomposition reaction.

Authors : James A. Behan, Serban Stamatin, Md. Khairul Hoque, Joana Vasconcelos, Federico Zen, Paula E. Colavita*
Affiliations : School of Chemistry and Centre for Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), University of Dublin Trinity College, College Green, Dublin, Dublin D2, Ireland

Resume : The incorporation of Nitrogen into carbon-based materials has been suggested as a route towards new electrode materials with properties amenable to applications in electrocatalysis and biosensing. Materials based on nitrogen-incorporated carbons have been suggested for use as support materials in fuel cells due to their corrosion resistance and metal-free ORR activity. The realisation of these proposed applications requires a fundamental understanding of the effects of nitrogen incorporation on both the bulk physical properties and the surface chemistry of carbon materials. To this end we have prepared nitrogen-incorporated amorphous carbon thin films with varying N-content via DC magnetron sputtering and characterised them using a combination of optical and electrochemical techniques. We present results indicating that nitrogen-incorporation produces films with lower optical gaps and faster electron transfer kinetics to outer sphere redox couples compared to the bare carbon films. Both the chemistry of the surface and the physical properties of the bulk are discussed for the purpose of understanding how structural changes induced in carbon materials by nitrogen incorporation may be best controlled to allow for the synthesis of new materials tailored for specific electrochemical applications.

Authors : Rakibul Islam (1), Anthony N.Papathanassiou (2), Roch Chan-Yu-Kin (3)g, Frederick Roussel (1)
Affiliations : (1) University of Lille- Sciences and Technologies, Unité Matériaux et Transformations (UMET) – UMR CNRS 8207, ;France (2) National and Kapodistrian University of Athens, Physics Department, Solid State Physics section, Greece; (3) University of Science and Arts of Oklahoma, Chickasha, USA

Resume : Core-shell single wall carbon nanotubes (SWCNT)/ polyaniline (PANI) nanocomposites were chemically synthesized and their structural, morphological, and dielectric properties were investigated as a function of SWCNT content. FE-SEM and TEM images confirm the core-shell nanostructural features of the composite. Xomplex dielectric permittivity measurements on the nanocomposites were carried out. The dielectric spectrum revealed that interfacial dielectric relaxation is observed because of conducting inclusion of nanofillers (SWCNT) into matrix (PANI). Furthermore, the relaxation process, which wa analyzed within the model of the Kohlrausch-William-Watts (KWW), existed at lower nanofiller loading, while, on increasing loading, the spectra gradually resembles that of a pure conductor. Such behavior can be interpreted by charge trapping and de-trapping phenomenon at core-shell interfaces. In addition, by monitoring charge capacitance in excess of dc-electrical conduction by changing the concentration of SWCT, can find promising applications in supercapacitor or gate memory devices.

Authors : Charalampos Lampadaris, Ilias Sakellis,Anthony N. Papathanassiou
Affiliations : National and Kapodistrian University of Athens, Department of Physics, Solid State Physics Section, Athens, Greece

Resume : Nano-omposites of polyvinylpyrrolidone (PVP) hosting dispersed graphene nano-platelets (GNP) were prepared from aqueous solutions, respectively. Electric charge transport and capacitance effects were studied by employing Broadband Dielectric Spectroscopy (BDS) in the frequency region 1 mHz to 1 MHz. Complex permittivity and complex ac (dynamic) conductivity as a function of composition and temperature were measured. The concentration-dependent insulator-to-metal transition has been investigated and the critical concentration threshold was determined in different ways: through the concentration dependence of the dc conductivity, as well as, of the onset of the dispersive of the dynamic ac conductivity at room temperature and, alternatively, exploring the temperature evolution of the dielectric spectra at isothermal conditions ranging from room temperature to 15 K. Percolation in PVP/GNP nano-composites is dictated by phonon-assisted quantum penetration of the host polymer matrix operating in parallel with conduction along physical contact of GNP, in accordance with predictions for systems consisting of a semi-conducting matrix and dispersed conducting inclusions [1]. Different modes for conductivity [2] are resolved and the electric charge transport dynamics is obtained by combined composition and temperature variation. References [1] C. Grimaldi, Theory of percolation and tunneling regimes in nanogranular metal films, Phys. Rev. B 89, 214201 (2014) [2] O. A. Syurik. D .I. Ageev. B. G. Cherednichenko and A. Konoplev Non-linear conductivity dependence on temperature in graphene-based polymer nanocomposite, Carbon 63 3173 (2013)

Authors : Leticia Poras Reis de Moraes, Debora Marani, Vincenzo Esposito, Daniel Zanetti de Florio, Marie Lund Traulsen, Fabrizio Gualandris, Simone Sanna, Fabio Coral Fonseca
Affiliations : Leticia Poras Reis de Moraes; Debora Marani; Fabio Coral Fonseca, Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP) - Av. Prof. Lineu Prestes, 2242, 05508-000, São Paulo, SP, Brazil Vincenzo Esposito; Marie Lund Traulsen; Fabrizio Gualandris, Simone Sanna, Department of Energy Conversion and Storage, Technical University of Denmark (DTU) Frederiksborgvej 399, Roskilde, DK-4000, Denmark Daniel Zanetti de Florio, Universidade Federal do ABC, 09210-580 – Santo Andre, SP, Brazil

Resume : By the virtue of versatility in composition, morphology, and structure, two-dimensional (2D) layered nanomaterials have attracted in the last decade huge interest. Such materials, consisting in stacked charged nanosheets intercalated with opposite charged exchangeable anions, are of great potential for the design and fabrication of nanomaterials in many applications. Indeed, the interlayer gallery provides a flexible space to accommodate various sized molecules (e.g. pollutants) and tune specific active sites at the atomic space (e.g. catalyst materials). The interest for 2D layered nanomaterials is also associated with the possibility of obtaining via exfoliation ultra-thin nanosheets with lateral dimensions of hundreds of nanometres and thickness of few nanometres. This unique class of nanomaterials has shown many unprecedented properties mainly originating from the dimensional anisotropy and nano-confinement effects. Herein we propose novel 2D layered ceria based oxides (e.g. CGO) synthesized via the heterogeneous precipitation. CGO materials were selected because of their strategic relevance in many technological applications (e. g. catalysis and electrochemical devices). The synthesized CGO layered materials were characterized for their composition, morphology and crystallographic features. The combined experimental results indicated that the layered CGO, with tunable dopant concentration, can be obtained in different morphologies by controlling the synthesis parameters.

Authors : Ji-Hyuk Choi, Eun Hee Jo, Hankwon Chang, Hee Dong Jang
Affiliations : Rare Metals Research Division, Korea Institute of Geoscience & Mineral Resources, Deajeon 305-350, Korea; Department of Nanomaterials Science and Engineering, University of Science & Technology, Deajeon 305-350, Korea

Resume : Supercapacitors, also known as the electrochemical double layer capacitors (EDLCs), have been of great interest as one of the most attracting energy storage devices due to their high power density (>10 kW/kg), long cycle life(>105), and fast charge–discharge processes (within seconds). As new class of carbon materials, graphene has recently received rapidly growing attention in EDLCs because of its high surface specific area, great mechanical strength and high electrical conductivity. In addition, graphene can be manufactured by cost-effective chemical methods with a high yield, making them potentially promising active materials for commercial and industrial applications In this study, The effects of morphological structure on electrochemical performance of crumpled graphene balls (CGBs) for application to supercapacitors were investigated. With one-step aerosol spray pyrolysis process, the CGBs were simply prepared from a colloidal solution of graphene oxide (GO). The effect of the average particle size of the as-prepared 3D CGR on the morphological and structural properties was systematically investigated. Furthermore, the electrochemical properties of supercapacitor fabricated with 3D CGR having a controlled size were evaluated. The specific capacitance of the electrode comprising of large-sized 3D CGR is up to 156 F/g with 88% excellent rate capability. In addition, the specific energy density and power density are up to 22 Wh/kg and 4 W/kg, respectively.

Authors : Jiwon Kim(a), Na-Ri Heo(a,b), Jae-Hong Lim(a), and Nosang V. Myung(c)
Affiliations : (a) Electrochemistry Department, Korea Institute of Materials Science, Changwon 641-831, Korea (b) Department of Materials Science and Engineering, Pusan National University Geumjeong-gu, Busan 609-735, South Korea (c) Department of Chemical and Environmental Engineering and Winston Chung Global Energy Center, University of California-Riverside, Riverside, California 92521, USA

Resume : We demonstrate the best thermoelectric properties of n-type Bi2(Te-Se)3 films at room temperature by the resonant level originated from resonant impurity. It is confirmed that the impurities known to provide the excess density of states found to be in the interstitial site in the Bi2Te3 unit-cell structure and led to increase in Seebeck coefficient without reducing the electrical conductivity. Moreover, the one order of magnitude enhanced electrical conductivity obtained by optimizing the morphology of the Bi2(Te-Se)3 films resulted the synergistic enhancement in the thermoelectric performance. It was achieved by introducing the modified pulsed electrodeposition technique with a control of both constant potential during the on-time period and constant zero current during the off-time period. Thus, for pulse-plated Bi2(Te-Se)3 films with the interstitial impurities, the Seebeck coefficient increased up to -106 ?V/K with the power factor of about 2000 ?V/mK2 at room temperature which is the best score as of now at room temperature among the reported Bi2(Te-Se)3 films.

Authors : Young Min Jhon, Seong-Il Kim, F. Gamiz
Affiliations : Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea; Departamento de Electronica y Tecnologıa de los Computadores, Universidad de Granada, Avda. Fuentenueva s/n, 18071 Granada, Spain; Departamento de Electronica y Tecnologıa de los Computadores, Universidad de Granada, Avda. Fuentenueva s/n, 18071 Granada, Spain

Resume : The transfer of graphene grown by CVD to other substrates may severely affect its properties, due its two-dimensional monolayer surface is very sensitive to chemical modification. Poly-methyl methacrylate (Sigma-Aldrich, 182265, PMMA) is a flexible substrate that is easy to handle and highly soluble in organic solvents, and so it is widely used as a supporting layer for the transferring process. However, the PMMA layer can leave residues on the graphene surface which can hinder graphene’s performance. In this work, we introduce thermal annealing process for the graphene monolayers transferred from Cu to SiO2/Si substrate to remove PMMA residue. Monolayer graphene grown by CVD was transferred onto a SiO2/Si substrate and dried in a vacuum desiccator to remove water and to facilitate its attachment to the SiO2/Si substrate. The sample was thermally annealed in a tube-type vacuum chamber with a halogen lamp, under the gas ambience (H2, Ar, or mixed gas of Ar/H2), and various vacuum annealing conditions. The experimental results show that it is very difficult to obtain a clean graphene surface without any deterioration by conventional thermal annealing method because the graphene reacts with the carbon by-products from the residual polymers. Although a higher annealing temperature facilitates removal of the polymer residue on graphene surface, it may also increase the amount of amorphous carbon. In this work, we examine various annealing temperatures, vacuum pressures, and ambient gases to remove the polymer residue efficiently. A higher annealing temperature removes more PMMA but also produces more amorphous carbon. Since the decomposed PMMA from the graphene surface is thought to be the source of the amorphous carbon that is produced on the graphene during the thermal annealing, we focused finding the best annealing condition for removing PMMA without producing the amorphous carbon. The removal of polymer residues on transferred graphene is investigated with XPS and Raman spectroscopy.

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Authors : Kisuk Kang
Affiliations : Department of Materials Science and Engineering, College of Engineering, Seoul National University, Korea (ROK)

Resume : The insertion of guest species in graphite is the key feature utilized in applications ranging from energy storage and liquid purification to the synthesis of graphene. Recently, it was discovered that solvated-Naion intercalation can occur in graphite even though the insertion of Na ions alone is thermodynamically impossible; this phenomenon enables graphite to function as a promising anode for Na-ion batteries. In an effort to understand this unusual behavior, we investigate the solvated-Na-ion intercalation mechanism using in operando X-ray diffraction analysis, electrochemical titration, real-time optical observation, and density functional theory (DFT) calculations. The ultrafast intercalation is demonstrated in real time using millimeter-sized highly ordered pyrolytic graphite, in which instantaneous insertion of solvated-Na-ions occurs (in less than 2 s). The formation of various stagings with solvated-Na-ions in graphite is observed and precisely quantified for the first time. The atomistic configuration of the solvated-Na-ions in graphite is proposed based on the experimental results and DFT calculations. The correlation between the properties of various solvents and the Na ion co-intercalation further suggests a strategy to tune the electrochemical performance of graphite electrodes in Na rechargeable batteries.

Authors : Craig A. J. Fisher, Takafumi Ogawa, Akihide Kuwabara, Hiroki Moriwake, M. Saiful Islam
Affiliations : Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan; Department of Chemistry, University of Bath, Bath BA1 7AQ, UK.

Resume : The design of the next generation of efficient, high-performance secondary batteries requires an intimate understanding of the atomic-level mechanisms controlling ion migration, crystal structure stability, interface reactions, and so on. Atomic level computer simulation methods provide a powerful means of obtaining such information, and are becoming essential to many state-of-the-art studies where, in addition to helping interpret and explain experimental results, they are increasingly used to screen and search for novel battery materials prior to synthesis. In this paper, examples of computer modeling of novel Na-ion and Mg-ion conducting oxides will be presented that provide insights into fundamental phenomena pertinent to their use in secondary batteries. Examples include classical molecular dynamics simulations of NASICON-structured Na3V2(PO4)3 examining the effect of phase changes on Na-ion mobility; surface structures of olivine-structured NaFePO4; and electronic structure calculations of NaCrO2 and NaFeO2 polytypes.

Authors : Seokwoo Jeon
Affiliations : Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 335 Science Road, Dajeon, 305-701, Republic of Korea

Resume : Designing a highly efficient catalyst is essential to improve the electrochemical performance of Li-O2 batteries for long-term cycling. Furthermore, these batteries have significant capacity fading due to the irreversible reaction characteristics of the Li2O2 product. To overcome these problems, we propose a bi-functional composite catalyst composed of electrospun Co3O4 nanofibers (NF) immobilized on both sides of the non-oxidized graphene flakes (NOGFs) as an oxygen electrode in Li-O2 batteries. The NOGF-based electrodes show high discharge capacity (10500 mAh/g) and superior cyclability (>80 cycles with 1000 mAh/g) due to large surface area of Co3O4 NFs, facile electron transport via interconnected NOGFs, and fast O2 diffusion through the network formed with ultrathin NOGFs and porous Co3O4 NF. For fundamental improvement for Li-O2 battery, three-dimensional (3D) nanostructured catalyst is a very attractive candidate due to its large surface area, short electron diffusion length and effective mass transport. To realize highly efficient 3D nanostructured catalyst for Li-O2 battery, we propose a hierarchically porous, 3D nanostructured catalyst. Here we demonstrate successful fabrication of 3D nanostructured gold with hierarchical pore distribution over a large area (~1X1 inch2) via proximity field nanopatterning (PnP) and electroplating. The newly developed nanostructured material in this study is promising as an efficient electrode for Li-O2 battery.

Authors : Martin Wilkening
Affiliations : Graz University of Technology, Christian Doppler Laboratory of Lithium Batteries, and DFG Research Unit 1277 'Mobility of Lithium Ions in Solids', Institute for Chemistry and Technology of Materials, Stremayrgasse 9, A-8010 Graz, Austria

Resume : The study of diffusion processes of small ions, such as lithium, sodium or even fluorine, in crystalline and amorphous solids has a long tradition in materials science. The studies published over the past years, either motivated by fundamental interest or driven because of applications behind, have brought out some quite interesting results in terms of mechanisms, fast diffusivity as well as spatially confined or interface-controlled motion. In particular, a thorough understanding of Li ion diffusion properties is indispensable if we want to develop new and powerful electrode materials and solid electrolytes for batteries. In order to meet this challenge ion dynamics are to be studied over a broad dynamic range. This purpose can be achieved by making use of complementary techniques such as Li nuclear magnetic resonance (NMR), such as echo and relaxation techniques, and conductivity spectroscopy. While the first, excluding field gradient techniques, gives access to jump rates and activation energies of the elementary hopping processes, ac and dc conductivity measurements, if recorded at median frequencies, are sensitive to overall macroscopic (ionic and electronic) transport. The present talk will spotlight latest results of studies focusing on (i) spatially confined Li diffusion in channel-structured and layered solids, e.g., LiC6 [1], and (ii) ion dynamics in (nano-)crystalline and single crystalline oxides such as garnet-type compounds [2]. Special emphasis will be put a) on materials offering extremely fast (liquid-like) translational diffusion, Li7P3S11, Li-argyrodites [3], and b) on compounds with ultraslow Li hopping processes, such as Li2O2 or Li2ZrO3 [4]. The NMR methods of choice mainly include frequency and temperature dependent relaxation measurements, 2D exchange spectroscopy as well as stimulated echo analyses preferably using both the Li(6) (spin-1) and Li(7) (spin-3/2) isotope. As an example, ultrafast Li ion dynamics with residence times as short as 1 ns at 263 K were probed for argyrodite-type Li6PS5Br [3a]. Such fast Li exchange correspond to conductivities of ca. 10 mS around room temperature. They are needed to develop all-solid-state lithium-based batteries taking advantage of highly conducting and inherently safe ceramic electrolytes. [1] a) B. Stanje, V. Epp, S. Nakhal, M. Lerch, M. Wilkening, ACS Appl. Mater Interfaces 7 (2015) 4089; b) V. Epp, S. Nakhal, M. Lerch, M. Wilkening, J. Phys.: Condens. Matter, 25 (2013) 195402; c) J. Langer, V. Epp, P. Heitjans, F. A. Mautner, M. Wilkening, Phys. Rev. B 88 (2013) 094304. [2] P. Bottke, D. Rettenwander, W. Schmidt, G. Amthauer, and M. Wilkening, Chem. Mater. 27 (2015) 6571. [3] a) V. Epp, O. Gün, H.-J. Deiseroth, M. Wilkening, J. Phys. Chem. Lett., 4 (2013) 2118. b) D. Wohlmuth, V. Epp, and M. Wilkening, ChemPhysChem. 16 (2015) 2582. [4] a) A. Dunst, V. Epp, I. Hanzu, S. Freunberger, M. Wilkening, Energy Environ. Sci. 7 (2014) 2739; b) P. Bottke, D. Freude, M. Wilkening, J. Phys. Chem. C, 117 (2013) 8114

Authors : Yong-Mook Kang*, Mi Ru Jo, Jeongyim Shin, Junghoon Yang
Affiliations : Department of Energy and Materials Engineering, Dongguk University-Seoul

Resume : Lithium ion battery has been rapidly developed for the applications in portable devices, electric vehicles (EV), and energy storage system (ESS) due to their high energy density and durable cycle life. From the practical viewpoint of electrode, high voltage charging and fast kinetics are essential to realize not only high power density but also high energy density for EV or ESS. However, it is quite challenging to improve both properties at the same time, especially for cathode materials. Thus, no matter what we develop for new cathode material, there have been severe limitations. Therefore, we devised a typical but synergistic way to fabricate a superb hybrid material in which the drawbacks of one material are completely covered by the advantages of the other material. In this synergistic way, we could successfully enhance the kinetic properties of Li3V2PO4 that is one of the representative high voltage cathode materials for Li ion battery, and utilize a conventional cathode material, LiCoO2, above 4.3 V. The detailed contents are as follows. Phosphate (PO4)3--based materials have been attracting tremendous interests due to their competitive energy density and remarkable thermal stability. Among these phosphates, monoclinic Li3V2(PO4)3 (LVP) was proposed as a highly promising cathode material, owing to its high operating voltage and very high theoretical capacity of 197 mAh g-1 when all three lithium ions are extracted/inserted between 3.0 and 4.8 V. In particular, its three-dimensional structure framework consisting of slightly distorted VO6 octahedral and PO4 tetrahedral sharing oxygen vertex provides large interstitial space that makes lithium ions capable of moving fast inside the structure [2]. However, just like the other metal phosphates, it shows a limited electron conductivity (10-8 - 10-9 S cm-1), which makes LVP to be difficult for practical applications [2]. Here, we present a sagacious design of LVP/carbon nanofiber with a distinctive morphology where LVP nanoparticles are anchored on the surface of carbon nanofiber. In general carbon-coated LVP 1D materials, there has been a problem that the carbon coating layer additionally interferes with lithium ion diffusion into LVP bulk. However, in our structure, LVP particles can directly contact with electrolytes leading to an improved lithium ion conductivity. Furthermore, carbon nanofiber can provide fast electron transport along its 1D pathway. As a result, it was demonstrated that this unique structure is favorable for simultaneously maximizing Li ion conductivity and electronic conductivity for great electrochemical improvement of LVP materials. LiCoO2 has the hexagonal α-NaFeO2 phase consisting of the layered rock-salt structure with the order of Li+ and Co3+ on alternating (111) planes in its cubic structure. When a Li/Li1-xCoxO2 cell is typically charged within limited composition range (0 < x < 0.5, 4.2V), it shows reasonably good capacity retention. However, the discharge capacity under the cut-off voltage of 4.2 V is around only 140 mAh/g, which is much lower than the theoretical value (274 mAh/g) of LiCoO2. Unfortunately, the practical use of LiCoO2 has been limited because its stability could be rapidly deteriorated at potentials higher than 4.2 V. Some research groups have reported that the poor cycling performance above 4.2 V is caused by structural instability induced by a phase transition from hexagonal phase to a monoclinic phase, which accompanies a volume change of ~2.6 % along the c-axis. To overcome the above problems, many researchers have developed lots of surface modifications that can improve the structural stability of LiCoO2. In this study, we tried to control the interlayer distance variation (lattice parameter c) though the substitution of phosphorus for Li+ sites by a phosphidation process. As a result, the unwanted phase transition could be suppressed by the existence of PO4 framework formed on the surface of LiCoO2 dramatically improving the cycleability and rate capability of LiCoO2 even above 4.5 V. Using this approach, we could easily change the surface O2-framework of LiCoO2 to PO4-framework. Consequently, phosphidated LiCoO2 came to retain very high structural stability and a stable surface film was formed in contact with electrolyte during charging/discharging. Phosphidated LiCoO2 exhibited greater bulk and surface stability compared to pristine LiCoO2 even in high voltage range, suggesting that this methodology will be also promising for other high-voltage cathode materials in lithium ion batteries.

Authors : Shu-Lei Chou*, Weijie Li, Yunxiao Wang, Jia-Zhao Wang, Hun-Kun Liu and Shi-Xue Dou
Affiliations : Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 Australia

Resume : Sodium-ion battery is a low cost energy storage device, which are similar in some ways to lithium-ion batteries. In both systems, Na/Li ions are shuttled between the battery’s positive and negative electrodes during charging and discharging. Taking into account recent concerns about a possible lithium shortage with the spread of electric vehicles, it is urgent to search for alternative energy storage systems that could complement the existing Li-ion technology. For this purpose, Na-ion technology can be a suitable choice in terms of battery cost, safety, and raw material abundance. Due to the increased size and heavier weight of the Na atom compared to the Li atom, the volumetric energy density and specific energy density obtainable for the sodium-ion battery would be significantly less than those obtainable with the lithium-ion battery. However, Na-ion batteries would be interesting for very low cost systems for grid storage, which could make renewable energy a primary source of energy rather than just a supplemental one. There are mainly three types of anode materials for sodium-ion batteries including carbon materials, alloy-based materials such as Sn, Sb, and P and insertion type sodium metal oxide materials. Alloy-based anode materials such as Sn, Sb, and P show high theoretical capacity of 847 (Na15Sn4), 660 (Na3Sb), 2,596 (Na3P) mAh g-1 towards sodium, but with more than 300% volume expansion. The theoretical capacity and the volume expansion ratio were shown in Figure 1. It can be found that the expansion ratio for Sodium based anode materials is more serious than Lithium based anode materials due to the bigger size of Na+ ions leading to poor cycle life. Several studies have shown that this massive volume expansion can lead to poor cycle life. Capacity fade can be caused by pulverization of the active particles or degradation of the electrode coating. Based on previous experience [1], the capacity fade of alloy-based negative electrodes is very sensitive to the choice of binder [2-4]. A good binder must ideally maintain adhesion of the electrode to the current collector, maintain ionic contact, and facilitate the formation of a stable interface with the electrolyte [5]. However, great efforts have to be made to find appropriate active materials for anodes of SIBs with cheaper price and environmental friendliness. Here, we will present our work on anode materials for sodium ion battery. The materials include carbon based materials, Sn-based materials and red phosphorous based composites with high specific capacity and excellent capacity retention [6-8]. 1. S. Komaba, Y. Matsuura, T. Ishikawa, N. Yabuuchi, W. Murata, S. Kuze, Electrochem. Commun. 2012, 21, 65. 2. J. F. Qian, Y. Chen, L. Wu, Y. L. Cao, X. P. Ai, H. X. Yang, Chem. Commun. 2012, 48, 7070 – 7072. 3. A. Darwiche, C. Marino, M. T. Sougrati, B. Fraisse, L. Stievano, L. Monconduit, J. Am. Chem. Soc. 2012, 134, 20805. 4. J. F. Qian, X. Y. Wu, Y. L. Cao, X. P. Ai, H. X. Yang, Angew. Chem., Int. Ed. 2013, 52, 4633-4636. 5. Y. Kim, Y. Park, A. Choi, N. S. Choi, J. Kim, J. Lee, J. H. Ryu, S. M. Oh, K. T. Lee, Adv. Mater. 2013, 25, 3045-3049. 6. W. J. Li, S. L. Chou, J. Z. Wang, H. K. Liu, and S. X. Dou, Nano Lett. 2013, 13(11), 5480-5484. 7. W.J. Li, S. L. Chou, J. Z. Wang, J. H. Kim, H.K. Liu, S.X. Dou, Adv. Mater. 2014, 26(24), 4037–4042. 8. Y. X. Wang, Y. G. Lim, M. S. Park, S. L. Chou, J. H. Kim, H. K. Liu, S. X. Dou, Y. J. Kim, J. Mater. Chem. A 2014, 2, 529-534.

Authors : Marketa Zukalova, Barbora Laskova, Ladislav Kavan
Affiliations : J. Heyrovský Institute of Physical Chemistry, v.v.i., AS CR, Dolejškova 3, CZ-18223 Prague 8, Czech Republic

Resume : Recently, Li4Ti5O12 (LTO), used as the negative electrode material in Li-ion batteries, has also been examined for the Na-ion battery. Na insertion in Li4Ti5O12 is accompanied with development of Na-substituted LTO phase with an about 4-5% larger unit cell volume which co-exists with Li4Ti5O12 in a single particle. In our work we studied Li and Na insertion into LTO of different particle size and synthetic history. The highest capacity and charging rate both for Li and Na insertion exhibited LTO prepared by sol-gel process pioneered in our laboratory. During testing of Li insertion by galvanostatic chronopotentiometry at 1C this material exhibited excellent stability over tens of cycles with almost 100% of theoretical capacity (175mAh/g). In contrary, commercial materials exhibited a capacity drop of about 30% after 50 cycles. In case of Na insertion, the charge capacity of sol-gel made LTO was 158mAh/g in the 1st cycle, however considerable capacity drop of about 40% was observed during cycling. This is obviously the consequence of irreversible structural changes induced by Na accommodation in the lattice. The best cycling stability for Na insertion exhibited commercial LTO from Altair. After 50 cycles at 1C the charge capacity decreased from initial 105mAh/g to 85mAh/g, i. e. of about 20%. This work was supported by the Grant Agency of the Czech Republic (contract No. 15-06511S) and by the Czech Ministry of Education, Youth and Sports (contract No. 8F15003).

Authors : G. C. Brunauer, G. Walch, B. Rotter, E. Esmaeli, J. Summhammer, A. K. Opitz, K. Ponweiser, and J. Fleig
Affiliations : G. C. Brunauer; B. Rotter; E. Esmaeli; K. Ponweiser, Institute for Energy Systems and Thermodynamics, TU Wien, Getreidemarkt 9 /E302, 1060 Vienna, Austria G. Walch; A. K. Opitz; J. Fleig, Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria J. Summhammer, Institute of Atomic and Subatomic Physics, TU Wien, Stadionallee 2 /E141, 1020 Vienna, Austria G. C. Brunauer, NOVAPECC GmbH, Hildebrandgasse 28, 1180 Vienna, Austria

Resume : Photon driven electrochemical reactions may contribute to future sustainable energy supply. Many different oxides (e.g. TiO2 or Fe2O3) have been tested so far to achieve photo-(electro-)chemical water splitting. Nevertheless, efficiency and/or materials stability are still not sufficient for widespread application of systems based on aqueous electrolytes. Photo-electrochemistry using solid oxide electrolytes, on the other hand, is an almost unexplored field. In such cells, operation temperatures of several hundred °C are required to enable sufficient oxide ion conduction. Very little knowledge is available on the experimental realization of such cells and on their problems. Here, we report results on the realization of a Solid Oxide Photo-Electrochemical Cell (SOPEC) using oxide ion conductors, operating at 400-500°C. The SOPEC includes a high temperature photovoltaic cell based on SrTiO3 in contact with La0.8Sr0.2CrO3, and a solid oxide electrolyte (Y doped zirconia). The photovoltaic cell part leads to open circuit voltages up to 920 mV at 400°C. The UV induced driving force is used in the electrochemical part of the cell to pump oxygen from low to high partial pressures, i.e. to convert radiation energy to chemical energy. This demonstrates the feasibility of high temperature photo-electrochemical cells for solar energy storage. The detailed characterization of the different resistance contributions in the system by DC and AC methods reveals the parts of the cell to be optimized for finally achieving high temperature photo-electrochemical water splitting. [1] G. C. Brunauer, B. Rotter, G. Walch, A. K. Opitz, G. Ponweiser, J. Summhammer, J. Fleig, Adv. Funct. Mater., 26 (2016) 120-128.

Authors : Hyun Suk Jung
Affiliations : School of Advanced Materials Science and Engineering, Sungkyunkwan University,Suwon, Korea

Resume : All solid-state solar cells based on organometal trihalide perovskite absorbers have already achieved distinguished power conversion efficiency (PCE) to over 22% and further improvements are expected up to 25%. These novel organometal halide perovskite absorbers which possess exceptionally strong and broad light absorption enable to approach the performances of the best thin film technologies. To commercialize these great solar cells, there are many bottlenecks such as long term stability, large scale fabrication process, and environmental issues. In this presentation, we demonstrate new fabrication processes for electron extraction layers such as electro-spray coating process and a novel 3-D nanopatterning technique that combines ion-assisted aerosol lithography (IAAL) and soft lithography. These processes are fairly suitable for realizing large scale fabrication of perovskite solar cells. In addition, we introduce a recycling technology of perovskite solar cells, which will facilitate the commercialization as well as solve the environmental issues of perovskite solar cells.

Authors : Yeon Sik Jung
Affiliations : Korea Advanced Institute of Science and Technology (KAIST)

Resume : Recently, quantum dot solar cells (QDSCs) based on a depleted heterojunction structure achieved outstanding progress in power conversion efficiency (PCE). However, despite their promising potential, there are still remaining challenges to be solved for further improvement of their PEC. Here, we report that increasing the doping level of the metal oxide can significantly boost the depletion region width in the QD layer and improve the PCE of metal oxide/QD heterojunction solar cells. The performance of ZnO/PbS QDSCs with a lightly doped ZnO (n-ZnO, n ~ 1016 cm-3) film or a heavily doped ZnO (n+-ZnO, n ~ 1019 cm-3) layer was systematically characterized to elucidate the effect of the metal oxide doping level. The introduction of n+-ZnO instead of n-ZnO achieves an approximately 30% increase in the depletion region width in the QD layer from ~186 nm to ~242 nm, which was quantitatively estimated on the basis of current density-voltage (J-V) characteristics and capacitance-voltage (C-V) measurements. The optimum thickness of the QD layer therefore also increases from ~220 nm (n-ZnO device) to ~300 nm (n+-ZnO device). As a result, n+-ZnO/PbS QDSCs demonstrate a maximum PCE of 7.55% and a Jsc of 23.5 mA/cm2, which are significantly higher than those of n-ZnO/PbS QDSCs (PCE = 5.52%, and Jsc = 16.7 mA/cm2). Furthermore, the highly conductive n+-ZnO can have dual functionality as both a n-type layer and a transparent conducting oxide (TCO), and enables the successful fabrication and operation of QDSCs (PCE ~ 7.33%) without an additional bottom indium tin oxide (ITO) layer typically used as a TCO.

Authors : Ladislav Kavan
Affiliations : J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague 8, Czech Republic

Resume : Graphene and titania find significant applications in dye sensitized solar cells as electrode materials for cathode and photoanode, respectively. The generic device is a liquid-junction photoelectrochemical cell with a dye-sensitized nanocrystalline TiO2 and Co-based electrolyte solutions. An alternative of this system is the solid-state dye sensitized solar cell in which the photogenerated holes are transported by a solid conductive material. Recently, this concept developed into the perovskite solar cell, exceeding 20 % conversion efficiency. Besides perovskite scaffold, titania is used for buffer layers in electron-collecting electrode. Here, the optimum blocking function is found for the sol-gel and ALD-made layers with thicknesses down to several nm. Accommodation of Li in TiO2¬ (anatase) and monoclinic TiO2(B) is applicable to the development of anodes for Li-ion batteries. The enhanced contribution of capacitive Li-storage in nanomaterials and faradaic pseudocapacitance in monoclinic TiO2(B) are of particular interest. These studies were further upgraded by investigation of titania nanomaterials labeled by oxygen isotopes 16, 17, 18 and insertion of Li 6 and 7 isotopes. Raman spectroelectrochemistry provided useful data about phase transitions during electrochemical Li-charging/discharging. The second-order Raman scattering in rutile, and the overlapping Raman features in anatase were addressed in detail. Acknowledgement: This work was supported and by the Czech Ministry of Education, Youth and Sports (contract No. 8F15003) and by the Czech National Science Foundation (contract No. 13-07724S).

Authors : Soo Young Kim
Affiliations : Chung-Ang University

Resume : Recently, the new technologies to produce renewable, sustainable energy have been invented such as wind energy, fuel cell, nuclear power, solar cells. Among those, organic photovoltaic cells (OPVs) have drawn a great attention due to its superior properties namely flexible, light weight, high efficiency, easy-making and low cost. The organolead halide perovskites have also emerged as an exciting material in photovoltaic research fields because of its large light-absorption coefficient, high carrier mobility and long carrier diffusion length. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been widely use as hole extraction layer (HEL) in OPVs and perovskite solar cells (PSCs) on account of its suitable band gap alignment with active layer and easy-fabrication via solution process. However, its acidic and hygroscopic nature makes it inappropriate for the real product [1]. To overcome the challenges caused by PEDOT:PSS, we have tried to use two dimensional materials instead of PEDOT:PSS as HEL in OPVs and PSCs, which include graphene oxide (GO), UV/ozone treated graphene, transition metal dichalcogenides (MoS2, WS2, TaS2, TiS2) and (NH4)2WS4. GO was synthesized by using Hummers’ method [2]. Graphene and transition metal dichalcogenides were prepared by chemical vapor deposition method or sonication process [3-5]. The lifetime comparison of OPV cells with UV/ozone-treated graphene and conventional PEDOT:PSS was conducted. The lifetimes were evaluated according to the ISOS-D-3 protocol with relative humidity of 90 % and temperature of 60 oC without encapsulation. The graphene underwent 5-min UV-ozone treatment. It is shown that the power conversion efficiency (PCE) of the PEDOT:PSS-based device rapidly decreased to ~ 0 % after 14-hour exposure in humid conditions while the UV/ozone-treated device continued to operate for 26 hours. This lifetime test suggests that more stable and efficient passivation can be achieved by replacing conventional PEDOT:PSS with UV/ozone-treated graphene. The current density-voltage characteristics of PSCs based on PEDOT:PSS, MoS2, WS2, and GO HEL are compared. The PCE of PEDOT:PSS based PSCs is 9.93%. The PCEs of MoS2, WS2, and GO based PSCs are 9.53, 8.02, and 9.62 %, respectively. Although PCE of WS2 based PSC was somewhat lower than that of PEDOT:PSS based ones, the PCE of GO and MoS2 based solar cell were similar to that of PEDOT:PSS based one, suggesting that GO and MoS2 HELs can be substituted for PEDOT:PSS. Therefore, it is considered that two dimensional materials could be used as HEL in OPVs and PSCs. [Acknowledgement] This research was supported in part by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (No. 2014R1A2A1A11051098) and in part by the International Cooperative R&D program through Korea Institute for Advancement of Technology (KIAT) funded by the Ministry of Trade, Industry and Energy (MOTIE) of Korea. [REFERENCES] 1. Jørgensen M., Norrman K., Krebs F. C.: Sol. Energy Mater. Sol. Cells 92, 686 (2008). 2. Park Y., Choi K. S., Kim S. Y.: Phys. Status Solidi A 209, 1363 (2012). 3. Kwon K. C., Dong W. J., Jung G. H., Ham J., Lee J.-L., Kim S. Y.: Sol. Energy Mater. Sol. Cells 109, 148 (2013). 4. Le Q. V., Nguyen T. P., Choi K. S., Cho Y.-H., Hong Y. J., Kim, S. Y.: Phys. Chem. Chem. Phys. 16, 25468 (2014). 5. Kwon K. C., Kim C., Le Q. V., Gim S., Jeon J.-M., Ham J., Lee J.-L., Jang H. W., Kim S. Y.: ACS Nano 9, 4146 (2015).

Authors : Yang Yang Li; Jian Lu; Jie Zhang; Chris Lee; Yawen Zhan; Shanshan Zeng; Haidong Bian
Affiliations : a Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong b Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong c Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong f City University of Hong Kong Shenzhen Research Institute, 8 Yuexing 1st Road, Shenzhen Hi-Tech Industrial Park, Nanshan District, Shenzhen, China g Centre for Advanced Structural Materials, City University of Hong Kong Shenzhen Research Institute, 8 Yuexing 1st Road, Shenzhen Hi-Tech Industrial Park, Nanshan District, Shenzhen, China

Resume : We present economical and versatile approaches to achieve structural precision, good scalability and novel periodicity of nanomaterials for energy applications. These novel approaches build on the bottom-up electrochemical techniques and are applicable to a wide range of materials and functions, including 1) electrochemically fabricated nanoporous metallic films, 2) electrochemically modified metal oxides, and 3) electrochemically treated bulk metal frameworks of large surface areas. For example, a convenient method is developed for mass producing monolithic porous metallic nanostructures of high specific surface area and improved mechanical performance. Alloys are first mechanically pretreated and grain-refined using the convenient surface mechanical attrition treatment (SMAT) and then dealloyed. The reactive metal component can be effectively removed at an accelerated rate, while the inert metal component forms a finer porous structure with the undesirable “self-coarsening” effect (the undesired structure rearrangement upon long-time soaking in the etchant that results in larger structural features to reduce the material overall surface area) largely suppressed. Monolithic supercapacitor electrodes of superior performance are enabled by the Cu-based bulk frameworks fabricated using the novel method reported in this study.

Authors : Hadi Sedaghat Pisheh (a); Negar Gheshlaghi (a); Hilmi Ünlü (a,b)
Affiliations : (a) Nanscience and Nanoengineering Programme, Institute of Science and Technology İstanbul Technical University, Maslak Istanbul 34469 TURKEY (b) Department of Physics, Faculty of Science and Letters İstanbul Technical University, Maslak Istanbul 34469 TURKEY

Resume : Colloidal semiconductor nanocrystals (NCs), also termed quantum dots (QDs), are composed of a core surrounded by different band gap material of its kind. With respect to core NCs, core/shell systems exhibit generally enhanced stability against photodegradation. So an important strategy to improve NCs’ surface passivation is their overgrowth with a shell of a second or third semiconductor, resulting in core/shell (CS) or core/shell/shell (CSS) heterostructured nanocrystals. Furthermore, by the appropriate choice of the core and shell materials, it is possible to tune the emission wavelength in a larger spectral window than with both materials alone. In this work we report a synthetic route to prepare ZnSe/Zn(Cd)S/Cd(Zn)S and CdSe/Zn(Cd)S/Cd(Zn)S Core/Shell/Shell heterostructured NCs. The synthesized nanocrystals were characterized by using high resolution TEM, x-ray diffraction (XRD) for structural properties and UV absorption and fluorescence techniques for optical properties. An ‘‘inverse’’ quantum dot quantim well (QDQW) structure has been realized with the synthesis of CdSe/ZnS/CdS and ZnSe/ZnS/CdS NCs, as here the larger-bandgap material is embedded between the lower-bandgap ones. In the case of CdSe/CdS/ZnS, CdS as a strain-reducing intermediate shell sandwiched between the core NC and the outer shell. The interest of such structures lies in the combination of low strain, provided by the intermediate layer (CdS) serving as a ‘‘lattice adapter’’ and the outer shell (ZnS) which assures efficient passivation and charge-carrier confinement. The effects of lattice mismatch induced interface strain on the first exciton energy, capped core diameter and conduction and valence band energies of the quantum dots investigated. The induced interface strain from lattice mismatch between core and shell(multishell) calculated from continuum elastic theory and included in effective mass aproximation (EMA) to calculate corresponding capped core diameter. The results compared with bare core images from TEM to evaluate squeeze (stretch) amount in core size after compressive (tensile) shell deposition.

Authors : Jingwei Chen, Xu Wang, Jiangxin Wang, Pooi See Lee
Affiliations : School of Materials Science and Engineering, Nanyang Technological University, Singapore.

Resume : Supercapacitor among many energy storage devices can realize fast charge discharge and long term cycling stability, however, its practical application is greatly restricted due to low energy density caused by limited electronic and ionic conductivity of electrode materials. The layered structure of NiMn layered double hydroxide (LDH) endows it as a promising supercapacitor electrodes, but low electronic conductivity limits the performance. In this work, the NiMn LDH is sulfidized to enhance the electronic conductivity, facilitate charge transfer and promote faster reversible redox reactions, while realizing enhanced specific capacitance. During the sulfidation process, the incorporated graphite oxide (GO) in GO/NiMn LDH composites can be simultaneously reduced, leading to an enhanced electronic conductivity, subsided defects and heteroatom S doping into graphitic structure. The sulfidized composite can achieve better long term stability due to mitigated phase transformation. As a result, specific capacitance as high as 2246.63 F/g can be realized by the sulfidized GO/LDH composite at current density of 1 A/g, while at increased current density of 10 A/g capacitance of 1670.83 F/g can be retained, manifesting an excellent capacitance and rate performance in comparison to other sulfide based electrode materials. The sulfidized composite also promises an enhanced cycling retention of ~ 67 % after 1500 cycles, compared to only ~ 44 % of pure NiMn LDH.

Authors : G. A. Nemnes (1,2) , Adela Nicolaev (1) , T. L. Mitran (2) , N. Plugaru (3) , A. Manolescu (4) , S. Antohe (1)
Affiliations : (1) University of Bucharest, Faculty of Physics, MDEO Research Center, 077125 Magurele-Ilfov, Romania ; (2) Horia Hulubei National Institute for Physics and Nuclear Engineering, Str. Reactorului nr. 30, PO Box MG-6, Magurele-Ilfov, Romania ; (3) National Institute of Materials Physics, Atomistilor Str., No. 405A PO Box MG 7, 077125, Magurele, Romania ; (4) School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik, Iceland

Resume : Hybrid halide perovskite based solar cells witnessed unprecedentedly rapid development in the past few years in terms of photoconversion efficiency. In spite of the progress achieved so far, a number of issues still remain to be solved, such as long term stability, toxicity induced by the presence of lead, cost effective and robust hole transport materials (HTMs) and a better understanding of the charge transfer at the interfaces, which governs the device operation. By far the most widely used HTM is 2,2',7,7'-Tetrakis(N,N-di-4-methoxyphenylamino)-9,9'-spirobiflourene, known as spiro-MeOTAD. Although spiro-MeOTAD has certified qualities as HTM, ensuring a barrier-free hole passage from the halide perovskite to the metallic (gold) contact, it also reveals some drawbacks: it may be responsible for the degradation of the perovskite layer by forming pinholes, as organic hole conductor long term stability is questionable and it is a relatively high cost material. Recent efforts to replace spiro-MeOTAD with an more stable and less expensive inorganic HTM, include cooper based compounds such as CuI, CuSCN or copper phthalocyanine, which however partly compromise the photoconversion efficiency (PCE). A promising inorganic HTM is Cu2O, with a high carrier mobility. Solar cells based on Cu2O were reported to yield reasonable PCEs [1]. Based on these recent promising experimental results we investigate by ab initio density functional theory (DFT) calculations the band alignment and charge transfer at the Cu2O/halide perovskite interface. We identify the band offsets using the approach introduced in Ref. [2] and discuss the charge distribution in the vecinity of the interface. Electronic structure modifications induced by point defects in the Cu2O layer are investigated. In this context we assess the conditions for a reliable hole transfer. [1] S. Chatterjee and A. J. Pal, J. Phys. Chem C 120, 1428 (2016). [2] G.A. Nemnes et al., Phys. Chem. Chem Phys. 17, 301417 (2015).

Authors : Yayuan Tian 1,2,a), Chris Lee 1,2, Jian Lu 3, Yang Yang Li 1,2,b)
Affiliations : 1 Center of Super-Diamond and Advanced Films (COSDAF); 2 Department of Physics and Materials Science; 3 Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong (SAR)

Resume : Keywords: Surface Mechanical Attrition Treatment (SMAT), titanium dioxide, photocatalysis, strain-induced defects, supercapacitors. Defect-based material engineering has found a niche in bandgap modification, photocatalysis and energy storage. Using a process called surface mechanical attrition treatment (SMAT)—normally reserved for deforming the surfaces of bulk material—we propose that this process can also be applied to delicate surfaces, allowing for the creation of strain and defect-based effects through stress concentration, vacancy creation, and/or dopant injection. Furthermore, with the great diversity of processing parameters of SMAT, one can deliver tailored treatment specific to the surface being modified as well as for the functionality being desired. In this work, we illustrate this concept by implementing SMAT in the modification of titanium dioxide (TiO2) nanotube arrays, leading to improved photocatalytic efficiency under solar radiation. We also suggest that with the further inclusion of surface dopants due to SMAT—when combined with the strain induced by said process—also yield a synergistic effect in light-harvesting in the modified TiO2, which has led to additional long-term operational stability on top of improved photocatalytic behavior being observed. Finally, with the enhanced defect creation via SMAT, the capacitance of the material has been enhanced from its original performance, demonstrating the value of using SMAT as a novel step in the functionalization process, as well as an effective post-treatment on already functionalized surfaces. a) b)

Authors : Anh Tuan Pham, Anh Phuong Nguyen, Thi Thanh Huong Nguyen, Sunglae Cho
Affiliations : Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan 680 – 749, Republic of Korea

Resume : Thermoelectric are perhaps the simplest technology for direct thermal to electric energy conversion. The conversion efficiency of a thermoelectric material is related to the dimensionless figure of merit ZT. High ZT is a counter-indicated property of matter. The tin diselenide (SnSe2) layered crystals are potential candidates for thermoelectric applications because of their high Seebeck coefficient and electrical conductivity. In this work, bulk SnSe2 single crystals were synthesized by gradient temperature method. The confirmation of single crystalline and composition determination of the grown crystals have been made by using X-ray diffraction and EPMA Quantitative Analysis techniques, respectively. The layered structure was observed via FE-SEM images. Thermoelectric response including electrical conductivity, Seebeck coefficients has been investigated in wide temperature range of 20-700K by using transport properties measurement system. Carrier concentration was evaluated by the Hall effect measurement with the van der Pauw method. The power factor value show obvious temperature dependences. Specific results will be discussed.

Authors : Nguyen Thi Thanh Huong, Nguyen Anh Phuong, Pham Anh Tuan, Duong Anh Tuan, Nguyen Van Quang, Sunglae Cho
Affiliations : Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of Korea

Resume : Like other semiconductor materials in III - VI compounds group (GaTe, In2Se3), Gallium Selenide (GaSe) appears to be a promising candidate material for thermoelectric applications in the future with high beta SE index which proportional to ZT value of thermoelectric material. In this work, the GaSe single crystal was grown from the high purity Ga and Se by vertical Bridgman method. The grown crystal can be cleaved in layer by layer without difficulty, confirmed the layered structure of GaSe. Meanwhile, the X-ray diffraction (XRD) result indicates the crystalline perfection of the grown single crystal as hexagonal structure. The absorption spectra analysis revealed the energy band gap of 1.98 eV, which is comparable to the reference value of 2.03 eV. We will discuss on transport properties of annealing GaSe samples.

Authors : A. Cucu1, A.M.I. Trefilov1, A. Tiliakos1, I. Stamatin1, A. Ciocanea2
Affiliations : 1: University of Bucharest, Faculty of Physics, 3Nano-SAE Research Center, 405 Atomistilor Str., Bucharest-Magurele, MG-38, 077125, Bucharest Romania 2: University Politehnica of Bucharest, Power Engineering Faculty, Hydraulics, Hidraulic Machines and Environmental Engineering Department, 313 Spaliul Independentei Str., sector 6, 060042, Bucharest, Romania

Resume : Microbial Fuel Cells (MFCs) have been hailed as a promising technological solution for wastewater treatment in tandem with energy production. However, scaling MFC systems for high volume applications - as required in modern wastewater treatment facilities – has been impeded due to high internal resistances pertaining to the low efficiency of the oxygen reduction reaction (ORR) at the cathodic electrodes. To counter this issue, we developed a monochamber MFC employing highly conductive xerogel electrodes synthesized according to the resorcinol-formaldehyde method. Graphene oxide has been added into the precursor slurry, reducing into graphene in the xerogel matrix after thermal treatment. The cathodic electrode was treated with a strong peroxide solution to ease the ORR development; the anodic electrode was used as prepared. The MFC setup employed both electrolyte and microbiota collected from a functioning wastewater treatment facility in Romania. Finally, we characterized our system according to electrochemical activity, organic matter and nitrate removal efficiencies, as well as current and power density production.

Authors : Deepti Chaudhary, Neeraj Khare, V. D.Vankar
Affiliations : Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016, India

Resume : The photocatalytic water splitting using solar light is a potentially clean and renewable source for the hydrogen production. Among several materials, TiO2 is one of the most promising photocatalyst due to its low cost, chemical inertness and high photostability, however in natural sunlight the photocatalytic efficiency of TiO2 is very low due to its large band gap (3.2 eV). Therefore, the development of efficient visible light active photocatalysts has been an attractive research field from the viewpoint of maximum utilization of solar energy. In very recent years, plasmonic photocatalytic composites have great potential for use in applications and is one of the most promising photocatalytic systems for high solar energy utilization efficiency [1-5]. In this work, Ag/TiO2/MWCNT ternary nanocomposite with optimal properties that enhance photo electrochemical (PEC) water splitting performance and photocatalytic activity is reported. Initially, TiO2/MWCNT nanocomposite was synthesized by hydrothermal method and then Ag nanoparticles were chemically grafted over the surface of as-synthesized TiO2/MWCNT nanocomposite for the formation of ternary nanocomposite system. Photocatalytic response of the prepared nanocomposite was studied through the degradation of a methylene blue solution using a solar irradiation source. The PEC property of the ternary hybrid electrode was also characterized by the linear sweep voltammetry. The results of both the methylene blue degradation and photocurrent tests indicated that the photocatalytic and PEC activities of the Ag/TiO2/MWCNT ternary hybrid are much higher than those of bare TiO2 and binary hybrids. The photocurrent density of Ag/TiO2/MWCNT photoanode under visible light illumination (20 mW/cm2) was 1 mA/cm2 (at 1 V vs Ag/AgCl), which is about 4 times higher than binary composite. The enhanced electron transfer within the Ag/TiO2/MWCNT was also confirmed by the electrochemical impedance spectroscopy. The efficient PEC water splitting of the ternary nanocomposite can be attributed to the synergetic effect of Ag nanoparticles and MWCNT, which enhances the photoresponse property of TiO2 in the visible region based on the surface plasmon resonance (SPR) effect and enhanced charge separation ability. This work demonstrates a feasible route to improve the PEC catalytic performance of TiO2 towards water splitting under sunlight irradiation. References [1] Z. Lian, W. Wang, S. Xiao, X. Li, Y. Cui, D. Zhang, G. Li and H. Li, Scientific Reports, 5 (2015) 10461. [2] E. Liu, L. Kang, Y. Yang, T. Sun, X. Hu, C. Zhu, H. Liu, Q. Wang, X. Li and J. Fan, Nanotechnology, 25 (2014) 165401. [3] W. Jiang, S. Bai, L. Wang , X. Wang, L. Yang , Y. Li, D. Liu, X. Wang, Z. Li, J. Jiang and Y. Xiong, Small, 12 (2016) 1640–1648. [4] D. Chaudhary, M. Z. Ansari, N. Khare , V. D. Vankar, Journal of nanoscience and nanotechnology, doi:10.1166/jnn.2016.12814. [5] M. M. Guia, W. M. P. Wong, S.-P. Chai, A. R. Mohamed, Chemical Engineering Journal 278 (2015) 272–278.

Authors : Teeraphat Watcharatharapong, Sudip Chakraborty, and Rajeev Ahuja
Affiliations : Materials Theory Division, Department of Physics and Astronomy, Uppsala University, Sweden

Resume : Due to the high redox voltage, low cost and sustainability, recently synthesized sulfate-based Na-ion batteries have become quite promising as the next generation cathode materials. Fe based kröhnkite-type material Na2Fe(SO4)2·2H2O has been synthesized under low temperature, showing high Fe3 /Fe2 redox potential at 3.25 V (vs Na/Na ). However, the fundamental insight regarding this material is still with limited understanding as far the electrochemical behaviour is concerned, especially about the intercalation processes, which play a significant role in the battery performance. In this study, Density Functional Theory (DFT) based calculation using GGA U approximation were performed to theoretically investigate the electronic properties and electrochemical behavior with respective magnetic configuration. To obtain diffusion barrier, nudge elastic band calculations were also systematically envisaged. During sodium removal, the oxidation state of Fe-centre gradually changes from 3 to 2 until half-desodiation is achieved and this has been nicely corresponded to the reported experimental observation. Na channel is primarily prevailed in the (001) plane, although the Na diffusions through several pathways are slow because of the presence of water molecules. Nevertheless, according to low defect formation energy, some intrinsic defects are likely to form and might participate in Na-ion diffusion of this material.

Authors : Nishant Saini, Aadesh P. Singh, Bodh R. Mehta
Affiliations : Indian Institute of technology Delhi

Resume : Bismuth vanadate (BiVO4) thin film for water-splitting in photoelectrochemical (PEC) cell has great potential in the design of low-cost, environmental friendly solar-hydrogen production. Presently, the solar-to-hydrogen conversion efficiency through PEC route is too low for the technology to be economically feasible. Bismuth vanadate (BiVO4) is an attractive material for its use in PEC cell for generation of hydrogen because of its suitable band gap (2.4-2.6 eV), abundance, stability and cost-effectiveness. But, its performance in a PEC cell is limited by high rate of charge recombination, unfavourable bandedge position with respect to water redox level and slow electron transport. This paper reports an improved photoelectrochemical response of Bismuth vanadate thin films after depositing FeOOH co-catalyst. Bismuth vanadate thin films were prepared by RF-sputtering technique and modified by FeOOH deposited by electrodepostion technique. X-ray diffraction, Raman spectroscopy and UV-Visible spectroscopy structural, optical and surface morphological characterization. XRD studies revealed the presence of monoclinic phase of BiVO4. The UV-Visible absorption curves showed extended absorbance in the visible region. The photoelectrochemical (PEC) studies were carried out in 0.1M Na2SO4 electrolyte in three electrode configuration. PEC results showed improvement in the photocurrent density of Bismuth vanadate from pristine and shift in onset potential (Von) for coupled photoelectrodes of BiVO4/FeOOH under visible light illumination. Detailed effect of FeOOH on surface morphology, optical absorption, electrical and photoelectrochemical properties will be discussed.

Authors : (a) Soumen Saha, (b) Kandalam V. Ramanujachary, (c) Samuel E. Lofland and (a) and (d) Ashok K. Ganguli
Affiliations : (a) Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India (b) Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States (c) Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States (d) Department of Chemistry, Indian Institute of Technology and Institute of Nano Science and Technology, Mohali, Punjab 160062

Resume : We have developed efficient nanostructures of Cu-Co-Ni alloy with varied stoichiometry as an alternative to the costly Pt-based alloys for hydrogen evolution reaction (HER). These nanoparticles were synthesized using reverse micellar method. The size of the alloy nanoparticles varied from 40-70 nm. An enhanced catalytic activity as evident from high current density was observed for these Cu-Co-Ni (111) alloys which follows the Volmer–Heyrovsky mechanism. They have excellent stability (up to 500 cycles) and significant activity in acid media which might be due to the low hydrogen binding energy.

Authors : S. Saber1,2, M. Mollar1, A.M.El Nahrawy2, N.M.Khattab2, A.A.Eid2, M. M. Abo-Aly3, B. Marí1
Affiliations : 1 Institut de Disseny i Fabricació, Universitat Politècnica de València. Camí de Vera s/n 46022 València (SPAIN) 2National Research Center, 33El Bohouth St.(former El Tahrir St.)- Dokki - Giza - Cairo (EGYPT). 3Chemistry Department, Faculty of Science, Ain Shams University, Cairo (EGYPT).

Resume : In this study CuInSe2&CuInS2 (CIS) thin films were prepared on ITO glass substrate using electrodeposition technique in aqueous solution. The electrodeposited films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). The annealing effects on electrodeposited precursors were investigated. The chalcopyrite structure of CuInSe2/CuInS2 showed an enhancement of crystallinity after selenization/sulfurization treatment in Se/S atmosphere, respectively. XRD and SEM studies reveal a dramatic improvement of the crystalline quality of CIS films after annealing treatments. Mott-Schottky measurements were used to assess the conductivity type of the films and their carrier concentration.

Authors : G.Kaptagay, A.Akilbekov
Affiliations : Kazakh State Women's Teacher Training University, L.N.Gumilev Eurasian national University

Resume : Electrochemical water splitting has attracted substantial interest in the recent years as a key process in hydrogen production from sunlight and other sources of electricity. Recent experimental studies have demonstrated that Co3O4 is high-promising anode material for electrochemical water splitting due to its high catalytic activity in the oxygen evolution reaction (OER) [1]. In this context, understanding the interaction of Co3O4 surfaces with water is an essential preliminary step that can help to shed light on the atomic scale reaction mechanisms. Our attention is focused on investigation of Co3O4 (100) surface which are the most abundantly presented in Co3O4 nanoparticles [2]. Density functional method is applied to describe thermodynamics of electrocatalytic water splitting on the Co3O4 (100) surface. We calculated free energy changes along the reaction pathway using the computational standard hydrogen electrode (SHE) allowing us to replace a proton and an electron with half a hydrogen molecule at U = 0 V vs SHE. The analysis performed for the free energies is at standard conditions (pH = 0, T = 298.15 K) and U = 0. Using accurate DFT+U calculations, we shown that water adsorbs dissociatively on Co3O4 on the (100) surface [3]. Carbon doping of Co3O4 nanoparticles drastically changes their interaction with water. In this case the over potential decreased than in case of fluorine doping. In our investigations for water splitting on Co3O4 (100) surface carbon effectively than fluorine. References 1. I. C. Man, H.-Y. Su, F. Calle-Vallejo, H. A. Hansen, J. I. Martínez, N. G. Inoglu, J. Kitchin, T. F. Jaramillo, J. K. Nørskov, and J. Rossmeisl, ChemCatChem. 3, 1159 – 1165 (2011). 2. F. Zasada, W. Piskorz, S. Cristol, J.-F. Paul, A. Kotarba, and Z. Sojka, J. Phys. Chem. C. 114, 22245–22253 (2010). 3. G.A. Kaptagay, T.M. Inerbaev, Yu.A. Mastrikov, E.A. Kotomin, A.T.Akilbekov. Solid State Ionics 277 (2015) 77–82.

Authors : Alessandro Bellucci1, Paolo Calvani1, Marco Girolami1, Stefano Orlando2, Veronica Valentini1, Riccardo Polini3, Daniele Maria Trucchi1
Affiliations : 1 CNR-ISM, Via Salaria km 29.300, 00015 Monterotondo Scalo (RM) – Italy 2 CNR-ISM, Zona Industriale Tito, 85050 Tito Scalo (PZ), Italy 3 Dip. di Scienze e Tecnologie Chimiche - Università di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy

Resume : Black diamond is obtained by a controlled nanoscale periodic texturing of CVD diamond surface performed by means of ultra-short pulse laser. Such a process represents a technologically easy process to fabricate ripples with a periodicity that depends on the laser wavelength on diamond surface, able to drastically modify the interaction with solar radiation from typical optical transparency up to solar absorptance values even higher than 90%. Here, we demonstrate that surface texturing gives rise to a strong enhancement of photo-responsivity in the visible range (up two orders of magnitude larger than the starting transparent diamond film). The operating mechanisms of black diamond is discussed and explained by disentangling the optical enhancement from an electronic increased density of states within the diamond bandgap corresponding to an actual intermediate band able to support an efficient photoelectronic conversion of sub-bandgap photons (<5.47 eV) [1]. The introduction of an intermediate band results in an enhanced external quantum efficiency up to 800 nm wavelengths, without affecting the film transport capabilities. Here, we further discuss recent results of process optimization on polyrcrystalline diamond, such as a reduced periodicity of the ripples and fabrication of 2D periodic structures [2]. This study is relevant for the developments of very well controlled periodic structures on single crystal diamond, opening the path for novel applications. [1] P. Calvani et al., "Black Diamond for Solar Energy Conversion”, Carbon 105 (2016) 401-407. [2]A. Bellucci et al., “Optimization of Black Diamond Films for Solar Energy Conversion”, Applied Surface Science (2016) in press, DOI: 10.1016/j.apsusc.2016.02.107.

Authors : J. Hulik 1,2, F. Le Normand 1, F. Antoni 1, W. Uhring 1, P. Veis 2
Affiliations : 1 ICube, MaCEPV, 23 rue du Loess, 67037 Strasbourg, France; 2 Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F1, 84248 Bratislava, Slovakia

Resume : Diamond-like carbon (DLC) have been produced by pulsed-laser deposition (PLD) of highly-oriented pyrolytic graphite (HOPG) target on transparent substrates, like quartz or glass, in order to use DLC as a buffer layer to obtain graphene-like films on top of the multilayer structure of DLC by thermal annealing process performed in Ultra High Vacuum (UHV) chamber using temperatures as high as 1373 K. The process of DLC production by PLD has been investigated using several techniques. The plasma dynamics have been studied by the Camille iCCD camera by Photonetics equipped with internal filter wheel using several optical filters and different time delays. The optical emission spectroscopy (OES) has been used for the spectral analysis of the plasma and the determination of the plasma parameters under different deposition conditions (e.g. laser fluence, laser wavelength). The Andor Mechelle ME 5000 OES spectrometer equipped with iCCD camera Andor iStar has been used for this purpose.

Authors : A.Tencha1,2, K. Shavanova1,2, Y. Ruban1,2, N. Starodub2, Rositsa Yakimova1 and V. Khranovskyy1
Affiliations : 1Linköping University, Department of Physics, Chemistry, and Biology (IFM), 583 81, Linköping, Sweden 2National University of Life and Environmental Sciences of Ukraine15, Heroyiv Oborony st., 03041, Kyiv, Ukraine

Resume : Graphene has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Furthermore, graphene oxide and graphene based nanocomposites with transition metal oxides nanoparticles (G-MOx NPs and GOx-MOx NPs) are considered as novel prospective materials for energy storage in batteries and supercapacitors. To make an essential impact toward sustainable development, the fabrication technologies of G-MOx NPs and GOx-MOx NPs should be as eco-friendly as possible. We report on the “green” chemical synthesis of graphene via i) chemical treatment of graphite by conventional modified Hummers method (MHM) followed by ii) eco-friendly reduction of obtained graphene oxide by several “green” reducers: ascorbic acid (vitamin C), caffeic acid, D-glucose and anthocyanine containing berries extract. The prepared graphene and its predeceasing oxide were mixed by combinatorial approach with nanoparticles of transition metal oxides (Co3O4, Fe2O3, ZnO, TiO2). The microstructure and crystal structure of the nanocomposited were investigated by Scanning Electron microscopy and X-ray Diffraction, while the electrochemical characterization of nanocomposites electrodes was performed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results obtained are discussed in terms of modern advance in energy storage devices.

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Authors : Petra E. de Jongh, Peter L. Bramwell, Peter Ngene, Krijn P. de Jong
Affiliations : Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, The Netherlands

Resume : Carbon-supported light metal hydrides are relevant for a range of applications including reversible hydrogen storage, batteries (in electrodes and solid state electrolytes), and ammonia capture. Nanosizing of light metal hydrides has in general yielded significant improvements to their functionality, such as enhanced Li+ ionic conductivity, or largely enhanced reversibility and sorption kinetics in hydrogen storage.[1,2] We highlight in this presentation carbon supported LiH nanoparticles which have been very little studied so far, most likely due to the fact that common preparation techniques cannot readily be applied to LiH. We identified for the first time a procedure to prepare supported LiH nanoparticles [3]. Impregnation of a porous carbon material with a butyllithium solution followed by reaction with hydrogen and driving off the solvent yielded carbon-supported LiH particles ranging in size from 2 nm to micrometer scale. The impact of particle size and the type of carbon support on the hydrogen storage properties was studied in detail [3,4]. The optimized preparation of the LiH/C gives a nanocomposite that begins hydrogen release as low as 100 °C and 10.4 wt% (wrt LiH) is released. Most remarkably hydrogen release was reversible: uptake of up to 5.2 wt% can be performed at 200 °C and as low as 0.1 bar H2 pressure, while full uptake can occur within 5 minutes at 26 bar. This unprecedented behaviour can be attributed to optimization of the preparation procedure as well as a specific interaction with the carbon support [3,4]. [1] de Jongh and Adelhelm, ChemSusChem, 3 (2010), 1332. [2] Blanchard et al., Adv. Funct. Mater. 25 (2015), 182. [3] Bramwell et al, submitted. [4] Ngene et al., Nano Energy 22 (2016), 169.

Authors : Maksym V. Kovalenko, Marc Walter, Meng He, Kostiantyn Kravchyk
Affiliations : ETH Zürich, Department of Chemistry and Applied Biosciences, CH-8093, Zurich, Switzerland and Empa-Swiss Federal Laboratories for Materials Science and Technology, CH-8600, Dübendorf, Switzerland

Resume : Due to limited natural abundance of lithium, novel battery technologies are needed for large-scale, stationary storage of electricity. Such batteries can then be combined with renewable sources of electricity, for the best integration of a variety of sources into electrical grid. We will discuss the utility of nanoscale inorganic materials as cathode and anode materials in Mg-ion batteries. In particular, the focus will be on a balance between the performance, material’s synthesis costs and natural abundance of the constituting elements. Owing to the reduced diffusivity of Mg-ions in most materials, nanostructuring has been identified to be of drastically higher importance than in the case of alkali-ion (Li, Na) batteries. The cathodic side of a battery remains the bottleneck. In this regard, we present several metal sulfides, delivering capacities of up to160 mAh g-1, with plateau voltages of 1.1-1.2V. On the anode side, we present Bi nanostructures as convenient anodes for research purposes. In particular, Bi-based anodes operate in a variety of electrolytes, in which metallic Mg is non-operational due to oxidative passivation.

Authors : Antonio Gutierrez-Pardo, Aurora Gomez-Martin, Julian Martinez-Fernandez, Joaquin Ramirez-Rico
Affiliations : Departamento Física de la Materia Condensada - ICMS (Universidad de Sevilla-CSIC), Avda. Reina Mercedes S/N, 41012 Seville, Spain.

Resume : Carbon obtained by pyrolysis of natural cellulosic precursors is hard or non-graphitizing as no subsequent heat process leads to ordered graphitic materials. However, the addition of a transition metal to the precursor induces graphitization within solid carbon materials during the pyrolysis at moderate temperatures in a single processing step. Catalytic graphitization has been intensively employed to produce graphitic materials, but the complex catalytic process by transition metals is not completely understood despite the intense research activity. In previous research, graphitic carbon monoliths from pyrolyzed wood were successfully obtained and this graphitization step was shown to enhance the electrochemical storage capacity and thermal conductivity of the material. In this work we perform a kinetic and structural characterization of the graphitization reaction in-situ through differential scanning calorimetry coupled with mass spectrometry in situ during the pyrolysis and x-ray diffraction, evaluating the intermediate compounds formed during the process and the temperature differences in the onset of graphitization to understand the mechanism and optimize the desirable characteristics of the graphitic material.

Authors : I. Shchedrina 1, C. Corbel 1, O. Cavani1, J-P. Renault 2, M. Perdicakis 3, N.Ollier 1, H. Randriamahazaka 4, J. Ghilane 4
Affiliations : 1 LSI, Ecole Polytechnique, CEA, CNRS, Université Paris-Saclay, 91128, Palaiseau, France 2 NIMBE, CEA Saclay, IRAMIS, 91191 Gif sur Ivette, France 3 LCPME, Université de Lorraine, Villers-Les-Nancy, France 4 ITODYS, Université Diderot, Paris, France

Resume : The reactivity of carbonaceous surfaces and its homogeneity are expected to be strongly dependent on the chemical and structural defects that, as reported in literature, can be induced by various treatments, including irradiation [1-4]. The present work is focused on surface properties and heterogeneity changes in carbonaceous materials induced by irradiation and investigated by Raman and photoluminescence (PL) spectrometry at the micro scale. The aim is to investigate more specifically the evolution of the Raman and PL spectra before and after different types of irradiation and their correlation. Irradiation tests are performed in dry conditions for different types of carbonaceous materials: graphene single layer on different substrates, highly oriented pyrolytic graphite (HOPG), carbon filled polyvinylidene fluorid (BMA5 (PVDF)). For HOPG and BMA5 in the as-received state, the Raman and PL spectra depend on the carbonaceous material nature. The spectra evolution shows that the concentration of defects increases during the electron irradiation. After UV irradiation, the evolution of spectra reveals a strong dependence on the irradiation conditions (UV light wavelength, flux and dose) and on defect concentration. Moreover, for the graphene single layer on Ni after 1 hour of UV irradiation, the Raman and the PL spectra vary independently with the increase in UV flux intensity. Keywords: graphene, carbon filled polyvinylidene fluorid, irradiation, UV, Raman spectroscopy, photoluminescence. References: 1. Teweldebrhan D. et al. Appl. Phys. Lett., 94,013101–013103, (2009) 2. Kotakoski J. et al. PRL 106, 105505 (2011) 3. Giannazzo F. et al. Nanoscale Research Letters (2011) 4. Pimenta M ;A. et al. Phys. Chem. Chem. Phys., 9, 1276-1290 (2007)

Authors : M. Mohammed (1), D. Selli (2), I. Baburin (3), D. Ceresoli (4), D. Proserpio (5), S. Leoni (1)
Affiliations : (1) Cardiff University, School of Chemistry, CF10 3AT, UK (2) Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, Germany (3) TU Dresden, Institut für Physikalische Chemie, 01062 Dresden, Germany (4) CNR-ISTM, Institute of Molecular Sciences and Technologies, Milan, Italy (5) Dipartimento di Chimica Strutturale e Stereochimica Inorganica (DCSSI), Università di Milano, 20133 Milano, Italy

Resume : Research on novel carbon allotropes never loses momentum. The expectation of a larger variety than what is known so far is motivated by its ability to form tetrahedral sp3 compounds like diamond, as well as planar sp2 graphite. Between those two limiting geometries a manifold of intermediate cases is known, from fullerenes to nanotubes, from hyperbolic Schwarzites to carbon foams. While the planar sp2 unit implies layers of merged six-rings, as regular triangles tile the Euclidean plane, this is not necessarily true for structures based on sp3 centres. Diamond consists of adamantane-like cages of fused six-rings in chair conformation. On the other hand 3D structures with planar six-rings and tetrahedral centres seem to be intrinsically a problem, unless there is a certain amount of odd rings in the structure. Combination of odd and even rings is key to hard and transparent carbon materials, while entangling 1D nanotubes in regular pattern produces superior hydrogen storage materials. Dirac fermions appears in single sheet graphene, while electronic properties can be further tuned in few-layers gaphites. In the attempt to expand the catalogue of carbons, we have found novel graphenoid strcutures, based on sp2 centers, which nonetheless are not planar, i.e. they represent 3D gaphenes. They define a novel class of compounds, that can be derived from generalised graphite compounds, whereby different tilings of the plane can be used. Along this way, different graphites as well as graphenoid carbons can be obtained, which hosts interesting electronic properties. The chirality of some of them may represent the starting point towards pure carbon 3D Weyl fermion materials, which so far could be realised in exotic materials only. The possibility of experimentally accessing these materials from suitable precursors is also part of this study.

Authors : Che-Ning Yeh (1), Kalyan Raidongia (1), Jiaojing Shao (1,2), Quan-Hong Yang (2,3), and Jiaxing Huang* (1)
Affiliations : 1. Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA; 2. Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China; 3. Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China

Resume : Assemblies of graphene oxide (GO) sheets into macroscopic membranes are of great interest because of their promising applications in energy conversion, gas separation, molecular filtration, nanofluidic system and so on. In particular, GO membranes have been demonstrated to have excellent mechanical properties and their extraordinary stability in water has been noted, which is a prerequisite for their membrane applications in solution. However, this is counterintuitive because GO sheets become negatively charged on hydration and the electrostatic repulsion between the sheets should make the membrane disintegrate. In this study, we have discovered a long-overlooked reason behind this apparent contradiction. Our findings show that while neat GO membranes do, indeed, readily disintegrate in water, the films become stable if they are crosslinked by multivalent cationic metal contaminants. Such metal contaminants can be introduced unintentionally during the synthesis and processing of GO. This new insight improves the understanding of interlayer interaction in GO membranes and their durability, which is crucial for proper use of GO thin films. Strategies to avoid and mitigate metal contamination are discussed. We also demonstrate that we can take advantage of the crosslinking effect for synthesizing layered oxide materials. This simple and versatile synthetic strategy holds great potential to prepare hybrid materials for energy applications including Li-ion batteries, supercapacitors, and photocatalysis. The finding has wide implications in interpreting the processing–structure–property relationships of GO and other lamellar membranes and opens up new opportunities to study wet-chemical reactions confined in the few nanometers of space between layers.

Authors : Aadesh P. Singh and Bodh R. Mehta
Affiliations : Department of Physics, Indian Institute of Technology Delhi, New Delhi-110016

Resume : The photoelectrochemical (PEC) splitting of water for scalable and sustainable production of hydrogen (chemical fuel) requires a semiconductor to absorb light and generate electron?hole pairs, and a catalyst to enhance the kinetics of electron transfer between the semiconductor and solution. Therefore, building on high catalytic active hematite thin films based on oxygen evolution catalysts (OECs) are promising compounds as a high-performance Earth-abundant catalyst for photoelectrochemical hydrogen production. Here we present an experimental study on surface modification of hematite thin films with OECs to get enhanced PEC water splitting under visible light irradiation. We demonstrate that a dual modification, hydrogen treatment and OEC loading can achieve a considerably higher photocurrent density and more negative shift in the onset potential with respect to the pristine ?-Fe2O3 and exhibit long term stability under visible light illumination. The enhancement in PEC performance in OEC photoanode can be attributed due to the high electrocatalytic performance of OEC that facilitate the photo-generated electron mobilization which increases the amount of photo-generated holes involved in the water oxidation reaction and accelerates the kinetics of water oxidation.

Authors : Showkat H. Mir, Sudip Chakraborty, Prakash C. Jha, and Rajeev Ahuja
Affiliations : a Centre for Nano Science, Central University of Gujarat, Gandhinagar-382030, India b Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Box -516, Sweden c School of Applied Material Sciences, Central University of Gujarat, Gandhinagar-382030, India

Resume : Steam reforming are two processes which are used for the hydrogen and oxygen evolution reaction for production of energy. A large number of studies can be found in the literature regarding the production of new catalysts for steam reforming through copper-based and group 8?10 metal-based catalysts. Knowing that the boron sheet is the lightest 2D material and therefore exploring the catalytic activity of such monolayer system would be quite interesting, we use computational approach to explore the possibility for the same. Functionalization of the boron sheet with different elemental dopants has been explored and also determined the adsorption energy for each case. Thereafter, free energy calculated from the individual adsorption energy for each functionalized boron sheet subsequently guides us to predict which case of functionalization serves better for HER or OER. This in principle pave the way of extensive research in energy production using photocatalytic water splitting through oxygen and hydrogen evolution.

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Authors : Ho Won Jang
Affiliations : Department of Materials Science and Engieering, Seoul National University

Resume : The solar water splitting is the third generation of solar energy utilizing technology for future energy problem. Through the past years, the technology has been amazingly meliorated, and theoretical basis has been enormously progressed. In recent days, much endeavor has been dedicated to enhancing solar water splitting efficiency. For further improvement, we need to deeply reflect a perspective of charge generation and transport in photoelectrodes and at interfaces between the electrodes and water. One of the most appropriate strategies for this concept would be grafting plasmonics to the photoelectrodes generally based on oxide semiconductors. We present photoelectrochemical properties of TiO2 thin films and TiO2 nanorods with 0-dimensional (0D) plasmonic Au nanoparticles. Our results clearly reveal the substantial enhancement of photoactivity in TiO2 by incorporating Au plasmonic nanoparticles. We show that the enhancement is strongly dependent on the shape of the 0D Au nanoparticles, suggesting that the localized surface plamonic resonances with high electromagnetic fields act as really effective hydrogen evolution catalysts on oxide-based photoanodes. Another appropriate strategy to develop efficient and stable water splitting photoelectrodes is the utilization of a surface protection layer which prevents photocorrosion of semiconductor photoelectrodes such as Si. We show that solution-processed 1D TiO2 nanorods can be used as protection and antireflective layer for Si photocathodes. It is also shown that 1D TiO2 nanorods themselves have catalytic effect to split water. Using the 1D TiO2 nanorods, we demonstrate the state-of-the-art performance of Si photocathodes. Finally, we are going to show chemical vapor deposition method to grow wafer-scale 2D transition metal disulfides (TMDs) such as MoS2 and WS2. We transfer large-area thin films composed of 2D TMDs to Si substrate to prepare efficient and stable photocathodes for solar water splitting. Atomically thin TMD films play important roles in hydrogen evolution reaction. We show the catalytic effect of 2D TMDs to dramatically lower charge transfer resistances at the semiconductor (p-Si)/electrolyte (water) interfaces. Compared with a bare Si photocathode, substantially enhanced stability of TMD/p-Si photocathodes is also presented.

Authors : Benedicte Vertruyen, Magali Brisbois, Nicolas Eshraghi, Claude Karegeya, Abdelfattah Mahmoud, Frederic Boschini
Affiliations : GREENMAT, Department of Chemistry B6, University of Liège, B-4000 Liège, Belgium

Resume : Since the success story of lithium iron phosphate, other phosphate-based compounds have attracted a lot of interest as promising candidates for positive electrodes in lithium-ion or sodium-ion batteries. Their electronic conductivity usually has to be improved through the preparation of composite powders ensuring intimate contact between the active material and conductive carbon. We report on the one-step synthesis of composite precursors using spray-drying or hydrothermal synthesis routes, two techniques which offer easy scaling-up of production. We show that addition of a solid carbon source (carbon black or carbon nanotubes) into the solution has a strong influence on the powder microstructure and is very effective in improving the battery cycling performance, taking our recent results on phosphates [Fex(PO4)(OH)y.zH2O)] and fluorophosphates [Na2FePO4F, Na3V2(PO4)2F3] as examples. We also compare this approach with the addition of the carbon source as a soluble precursor (such as ascorbic acid or citric acid) where the in situ formation of carbon is achieved by a heat treatment in inert atmosphere (typically argon).

Authors : Osvalds Verners, Angelo Simone
Affiliations : Osvalds Verners, Angelo Simone: Faculty of Civil Engineering and Geosciences Delft University of Technology

Resume : Structural batteries have emerged as a possible solution for reducing weight and volume of structures for a variety of applications [1], ranging from portable devices to space and electric vehicles. In view of multifunctional structural composite applications, this talk reports the findings of a reactive molecular dynamics study. The study explores the dependence of structural failure in SiO2- or Al2O3-coated Si nanotube anodes on Li concentration. In particular, the relation between the anode’s interface-debonding failure mechanisms and Li content at different battery charging levels is investigated. On microscale level, the effect of Li content is quantified in terms of the interface mechanical failure strains and stresses. Further considering the anode’s failure resistance properties, the size range for observable nanoscale size effects is estimated. The latter objective is achieved by comparing the failure responses of 3-D-periodic slab interface structures. Within the scope of the study, we anticipate that Al2O3/SiO2 softening due to Li charging [2, 3] may contribute to an improved failure resistance. Similarly, we also expect that a reduction in Si stiffness due to amorphization that occurs during Li charging [4] would result in larger deformations than those corresponding to crystalline phases and, as a result, Li concentration dependent structural response. References: [1] L. E. Asp and E. S. Greenhalgh. “Structural power composites”. In: Composites Science and Technology 101 (2014), pp. 41–61. [2] S.-Y. Kim et al. “Self-generated concentration and modulus gradient coating design to protect Si nano-wire electrodes during lithiation”. In: Phys. Chem. Chem. Phys. 18 (5 2016), pp. 3706–3715. [3] A. Ostadhossein et al. “Atomic Insight into the Lithium Storage and Diffusion Mechanism of SiO2/Al2O3 Electrodes of Lithium Ion Batter- ies: ReaxFF Reactive Force Field Modeling”. In: The Journal of Phys- ical Chemistry A 120.13 (2016), pp. 2114–2127. [4] Z. I. Popov et al. “A theoretical study of lithium absorption in amor- phous and crystalline silicon”. In: Journal of Structural Chemistry 52.5 (2011), pp. 861–869.

Authors : Sarang Park, Tae-Hyung Kang, In-Suk Choi, Woong-Ryeol Yu
Affiliations : Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of KOREA; Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of KOREA; High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, Republic of KOREA; Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of KOREA

Resume : Due to their excellent mechanical properties and electrical conductivities, carbon nanofibers (CNFs) have been suggested for many applications including lithium ion battery electrodes. Since the specific capacity of electrode materials in nanoscale can approach to the theoretical values, macroscopic forms of these nanomaterials have been vastly researched that can have excellent properties in nanoscale at macroscale. In this study, CNF yarns were manufactured through a yarning process of composite CNFs (i.e., CNFs containing silicon (Si) nanoparticles or lithium iron phosphate (LFP) nanoparticles) for lithium ion battery microfiber electrodes. First, poly(acrylonitrile) (PAN) nanofibers containing Si or LFP nanoparticles were spun by coaxial electrospinning process. Then, PAN microfibers were pulled from the electrospun PAN nanofiber web and twisted. The PAN microfiber was hot-stretched to align PAN nanofibers and calcined into carbon nanocomposite yarns. The nanocomposite yarns were coated with polymer electrolytes by dip-coating method. The mechanical tests were carried out to quantitatively characterize the strength, stiffness, and flexibility of the carbon nanocomposite yarns and their electrochemical characterizations were carried out using freestanding yarns without conducting additives or binders.

Authors : Youbin Kwon, Tae-Hyung Kang, Woong-Ryeol Yu
Affiliations : Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of KOREA; Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of KOREA; Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of KOREA

Resume : Increasing demand in small, flexible electronic devices have promoted research and development of flexible electrodes. The fiber is the most promising form for flexible electrodes due to its flexibility and strength and applicability to textile fabrics. On the other hand, graphenes have excellent mechanical, thermal and electrical properties in nano-scale, being considered as preferred candidate of building blocks for such fiber electrodes. Due to the inertness of graphene, however, it is not routine to disperse and assemble them into a fiber. Instead, graphene oxide (GO) has been used for fiber manufacturing because it can form liquid crystals, which is important to make fibers through wet-spinning. This research is aimed to explore an efficient manufacturing method of strong GO fibers and their potential applications to flexible electrodes. In this study, GO fibers are manufactured via liquid crystal wet spinning process. First, liquid crystal GO spinning dope is prepared in aqueous solution and spun into rotating coagulation bath. During wet spinning process, GO is aligned in flow direction, forming into a bundle structure. Spun GO bundles are gathered, combined, and twisted into GO yarns. The GO yarns are expected to have enhanced strength due to densification and lateral pressure of GO fibers inside yarns. Finally, the mechanical and electrochemical properties of GO yarns are characterized to investigate their applicability to flexible electrodes.

Authors : H. Comas Rojas, S Bellani, F. Fumagalli, M. Schreier, A. Mezzetti, S. Leonardi, M. Meyer, L. Meda, G. Lanzani, M. Graetzel, F. Di Fonzo, M. R. Antognazza
Affiliations : Center for Nano Science and Technology, Italian Institute of Technology, Via Pascoli 70/3, 20133 Milano, IT Institut des Sciences et Ingénierie Chimiques, EPFL, CH-1015 Lausanne, CH Eni S.p.A. Istituto ENI Donegani, via G. Fauser 4, 28100 Novara, IT

Resume : The direct conversion of solar energy into fuels, H2 in particular, at a simple and low cost semiconductor/water junction is still a challenge. Despite the theoretical simplicity of such a device, limitations in suitable semiconductor materials have hindered its development. Recently, few authors started exploring the potential of organic and hybrid organic-inorganic semiconductors, as an alternative to the usual transition metal oxides or more costly III-V semiconductors, in photoelectrochemical systems. Most reports described performances in the order of 1 mA/cm2 at the reversible hydrogen electrode potential (RHE), relatively low onset potentials and limited stability. Here we report our recent results on the optimization of a hybrid organic-inorganic photocathode for the direct conversion of solar light into chemical energy. Starting from a prototypical P3HT:PCBM blend as photoactive element, we focused our attention on different interfacial layers and their influence on the photocathode performances. The photocatalytic activity and long-term stability of a simple, catalysed, bulk heterojunction is proven and the specific effect on hydrogen generation performances of electron- and hole- selective contacts is investigated. The relevance of our findings can be summarized in few key points: (i) high performances with a maximum photocurrent of 8 mA/cm2 at RHE and 50% IPCE; (ii) optimal process stability with 100% faradaic efficiency along the whole electrode’s lifetime; (iii) excellent energetics with onset potential as high as +0.7 V vs RHE; (iv) promising operational activity of several tens of hours and (vi) by-design compatibility for implementation in a tandem architecture. In addition, we realized a large area, all-solution processed device as the first proof of concept of the high versatility and up-scaling potential of our approach. Collectively, this set of features establish the hybrid architecture we developed well ahead of existing reports on organic photoelectrochemical systems and suggest the potential of the hybrid organic-inorganic photoelectrochemical (HOPEC) concept as real contender to the traditional inorganic counterpart.

Authors : A. Mukhtarova, S. Valdueza-Felip, L. Redaelli, C. Durand, C. Bougerol, E. Monroy, and J. Eymery
Affiliations : University Grenoble Alpes, 38000 Grenoble, France; CEA-Grenoble, INAC-PHELIQS, 17 av. des Martyrs, 38000 Grenoble, France; CNRS-Institut Néel, 25 av. des Martyrs, 38000 Grenoble, France

Resume : InGaN semiconductors are promising for hybrid tandem solar cells due to their intrinsic properties and tuneable direct bandgap in the visible spectrum. Best solar cell efficiencies are obtained in structures with an active region consisting of InGaN/GaN multiple quantum-wells (MQWs), which delays the onset of misfit relaxation. However, to further improve the photovoltaic (PV) characteristics, it is necessary to optimize the active region design. In this work, we investigate the dependence of the PV performance of In0.1Ga0.9N/GaN (1.3/8.7 nm) MQW solar cells as a function of the number of wells (5-100, i.e. active region thickness of 50-1000 nm). The In content and QW/barrier thicknesses were chosen so as to limit the strain relaxation and the formation of structural defects. Increasing the number of wells from 5 to 40 significantly improves the PV characteristics (Voc and Jsc) under 1 sun of AM1.5 illumination, resulting in a 10 fold enhancement of the conversion efficiency (0.9%; maximum peak external quantum efficiency of 38% at 380 nm). A saturation of Jsc (and hence of the efficiency) is measured for cells with active regions above 40 MQWs. This feature is attributed to carrier collection losses and increased recombination in the MQW region associated with its incomplete depletion. A hole diffusion length in the MQW region of 48±6 nm is estimated from diffusion and drift current equations, taking into account the depletion width value extracted from capacitance measurements.

Authors : Thi Xuan Huong Le, Martin Drobek, Mikhael Bechelany, Sophie Tingry, Marc Cretin
Affiliations : IEM (Institut Européen des Membranes), UMR 5635 (CNRS-ENSCM-UM), Université de Montpellier, Place E. Bataillon, F- 34095, Montpellier, France

Resume : Scarcity of pure water worldwide is dramatically affecting the economic development of Third Countries but also the industrial growth of others. Electrochemical Advanced Oxidation Processes (EAOPs) are clean technologies for water recycling and reuse thanks to the production of hydroxyl radicals by electrolysis (i.e. needing an external energy source). We propose here an autonomous electrochemical cell fed by the direct green electrical energy coming from an abiotic electrode for glucose oxidation at gold anode (CF@Au) and oxygen reduction (Eq. 1) at a novel (Carbon Felt (CF)/porous Carbon (pC)) cathode. In this concept, electrons coming from glucose oxidation allow oxygen reduction, formation of hydrogen peroxide and then hydroxyl radicals generation through the Fenton reaction in presence of added iron (Eq. 2): O2 + 2H+ + 2e- → H2O2 (1) Fe2+ + H2O2 + H+ → Fe3+ + •OH + H2O (2) The highly active cathode is fabricated by an attractive route combining Atomic Layer Deposition (ALD) of metal oxide (ZnO) on commercial carbon felts (CF) followed by its subsequent solvothermal conversion to corresponding MOFs (ZIF-8). The as-prepared composite material was further calcined at high temperatures under controlled atmosphere forming porous carbon-based (pC) supports with high specific surface area and enhanced conductivity. The morphology, thickness and homogeneity of the obtained composite materials (CF/pC) were studied at different locations, using a high resolution scanning electron microscope (FESEM, Hitachi S-4800). X-ray diffraction analysis has been performed to investigate materials crystallinity. The N2 sorption-desorption isotherms of the virgin CF and porous carbon coated CF were measured. TGA, FTIR and XPS measurements of the as prepared composite materials were also conducted. Degradation kinetics of Acid Orange 7 (AO7) at CF/pC cathode by •OH radicals, a powerful oxidant, from Fenton reaction (Eq. 1), was monitored by UV-Vis spectrophotometry, HPLC and TOC analysis to prove the efficiency of the composite material for the mineralization of these bio-refractory model molecules. On the other hand, to supply electrons for the oxygen reduction reaction (ORR) into oxygen peroxide (Eq. 1), power was generated from glucose electro-oxidation at the anode manufactured by electrodeposition of gold particles, an efficient electrocatalyst for glucose oxidation. The CF@Au electrode was chosen because of its large electrochemical surface area, its excellent chemical stability, its high conductivity and the biocompatibility of the nanostructured gold films. The catalytic properties of both anode and cathode induce a stable output power maintained for at least one month. From that, pollutants are degraded efficiently, showing the high potential of this Fuel Cell-Fenton based system as a promising green technology for both environmental and energy areas. [1] Thi Xuan Huong Le, Mikhael Bechelany, Joffrey Champavert and Marc Cretin, A Highly Active Based Graphene Cathode for Electro-Fenton Reaction, RSC Advances, 2015, 5, 42536 – 42539

Authors : Barun Chakrabarti, Vladimir Yufit, Farid Tariq, Javier Rubio-Garcia, Dany Nir, Anthony Kucernak, Nigel Brandon
Affiliations : (Chakrabarti, Yufit, Tariq, Nir, Brandon) Department of Earth Science Engineering, Royal School of Mines, Imperial College London, South Kensington, London SW7 2AZ, U.K.; (Rubio-Garcia, Kucernak) Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K.

Resume : The application of fuel cell grade gas diffusion layer carbon paper (CP) electrodes in the all­ vanadium redox flow battery (VRFB) has allowed the maximum power density to be achieved for the system [1]. Up till today, the possible performance loss mechanisms of the electrodes due to poor micro-­structurally related mass transport of the electrolyte have not been understood nor been studied in much detail. In this work, time resolved 3D /4D imaging was used to study in-­situ the infiltration mechanism of the vanadium-­based electrolytes at four different concentrations. The wetting mechanisms have been analysed and the influence of respective parameters are discussed. The same CP electrodes are later subjected to electrophoresis in N,N'­dimethylformamide (DMF) consisting of reduced graphene oxide (rGO). EPD is conducted at a voltage of 300 V and an inter­-electrode distance of 15 mm. Thermal post­ treatment of the CP worsens electrochemical performance (measured in terms of cyclic voltammetry and electrochemical impedance spectroscopy). X­ ray computerized tomography (XCT) confirms an increase in the electrochemical surface area with rGO. Furthermore, XCT confirms that the deposition also penetrates into the substrate. Raman analysis shows that the rGO deposited is more amorphous than the CP electrode. An enhancement in the electrochemistry of the all­-vanadium redox flow battery catholyte is also observed when employing the modified samples for cyclic voltammetry and impedance tests. Polarisation tests show some marginal improvement of peak power densities in an all­vanadium redox flow battery after depositing rGO on the CP electrodes. Too much compression tends to clog up the pores of the CP by the deposited rGO and thus a torque of 4 Nm was used in most cases. Round­-trip efficiencies showed further improvements than peak power densities. Reference ======== [1] Q. H. Liu, G. M. Grim, A. B. Papandrew, A. Turhan, T. A. Zawodzinski and M. M. Mench. High Performance Vanadium Redox Flow Batteries with Optimized Electrode Configuration and Membrane Selection. Journal of the Electrochemical Society 159 (2012) A1246-­A1252.

Authors : Dr. Navnita Kumari, Professor Bodh Raj Mehta
Affiliations : IIT Delhi

Resume : One pot synthesis of MoS2 nanoflakes: Effect of temperature on structural & optical properties Navnita kumari1*, B. R. Mehta1 1Department of Physics, IIT Delhi, New Delhi Corresponding Author E mail:- Abstract In family of Transition Metal Chalcogenides (TMDs), Molybdenum disulfide (MoS2) is a highly capable material for energy harvesting applications such as lithium ion batteries (LIBs), photocatalysis, photoelectrochemical as well as electronic device etc. MoS2 nanoflakes and nanoflowers were prepared by one step hydrothermal route with uniform morphology in temperature range 150-220°C. From XRD and HRTEM it has been clearly observed that grown nanoflakes have hexagonal primitive structure. Orientation of grown nanoflakes and flowers shows at (002) plane with interplanar spacing 0.61 nm and (100) plane having 0.32 nm which confirmed growth of MoS2 in desired pattern and signature of hexagonal arrangement. Temperature affects the formation of nanoflakes conversion towards 3D nanoflowers. FTIR transmission spectrum shows the vibrational bonding around wave number 467 cm-1 which is signature peaks of bonding between S-Mo-S with different morphology its showing shift in nature which may be due to another bonding of Mo-O at around 451 cm-1 which is grown at temperature 220°C. In Raman spectra prepared nanostructure shows a difference between two consecutive peaks is the range of 18 cm-1 to 24 cm-1 which indicates its change towards monolayer to few layers. The distance between two consecutive peaks is around 19 cm-1 which is clear signature of momolayer formation. Conversion of indirect band gap to direct band gap in monolayer structure has been confirmed by photoluminescence (PL) studies. This monolayer to few layers structures potentially important for different device application point of view.

Authors : Jiwon Kim(a), Jae-Hong Lim(a), and Nosang V. Myung(b)
Affiliations : (a)Electrochemistry Department, Korea Institute of Materials Science, Changwon 641-831, Korea (b)Department of Chemical and Environmental Engineering and Winston Chung Global Energy Center, University of California-Riverside, Riverside, California 92521, USA

Resume : Augmented thermoelectric performance of p-type Sb2Te3 films is investigated by introducing the interfacial energy-barrier scattering (i.e., barrier heights) occurring at both grain boundaries and interfaces between embedded second-phases. It’s postulated that the barrier heights filter the low energy carriers, thus favoring a high Seebeck coefficient. The Sb2Te3 nanocomposite films were formed via solid-state phase transition using amorphous Sb-Te electrodeposits as the starting materials. The initial composition and post-annealing profiles are varied to control the formation of the γ-SbTe and Te second nanophase. Electrical and thermoelectric properties are correlated with the physical properties, where the enhanced Seebeck coefficient at a given carrier concentration is interpreted that the energy-dependent carrier filtering effect is at play. The barrier height was indirectly manifested by measuring their difference in the valence band, advocating the possibility of a strong energy dependent charge scattering. On a promising note, the formation of the γ-SbTe/Sb2Te3 and Te/Sb2Te3 nanocomposites readily produces an effect on the interfacial energy-barrier scatterings along with the enhanced power factor – making it a candidate as a promising p-type thermoelectric material for room-temperature operational micro-thermoelectric power generator.

Authors : Shuen Liang, Yalin Zhu, Keping Chen, Chunrong Tian, Jianhua Wang
Affiliations : 1 Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang, China 2 College of Material Science and Engineering, Southwest University of Science and Technology of China, Mianyang, China

Resume : Due to limited conventional fossil energy and increasing greenhouse gas emission, highly efficient utilization of energy and developing new energy storage materials become more and more important. PCMs (Phase change materials) can provide high energy storage density and near isothermal heat storage, and contribute to more environmentally friendly energy use. As shell materials of encapsulated PCMs, organic–inorganic hybrids can combine the advantages of both organic and inorganic materials. In this work, we nanoencapsulated n-octadecane with PS–SiO2 (polystyrene–silica) hybrid shell in miniemulsion. FT-IR spectroscopy and XRD analysis were used to verify the chemical composition and crystallinity of the as-prepared nanocapsules, respectively. SEM and TEM results demonstrated that these nanocapsules possess regular bowl-like morphology (diameter: 320–440 nm) and well-defined core-shell structure. Phase change properties of the nanocapsules were characterized by DSC analysis, revealing that high melting enthalpies (79.5–126.0 J/g) and encapsulation ratios (37.3–59.1%) have been achieved. The crystallizing behaviors were clarified by means of temperature-dependent XRD measurements. TGA results revealed that the thermal stability of the nanocapsules is improved largely, compared with that of pristine n-octadecane. After 1000 melting/solidifying thermal cycles, the chemical structure, morphology, and phase change enthalpies of the nanocapsules were maintained perfectly, and supercooling behavior was mitigated obviously.

Authors : Yalin Zhu, Shuen Liang, Chunrong Tian,* Jianhua Wang
Affiliations : 1 Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang, China 2 College of Material Science and Engineering, Southwest University of Science and Technology of China, Mianyang, China

Resume : RPU (Rigid polyurethane) foams possess low thermal conductivity, high mechanical and chemical stability and high durability, and their thermoregulation property can be enhanced markedly by incorporation of various encapsulated PCMs (phase change materials). As a result, they can be used as ideal heat-insulated building materials, to enhance the energy efficiency and sustainability of buildings. The significant development of NanoPCMs (nanoencapsulated phase change materials) in recent years, especially that with inorganic shell materials, might offer new opportunity for the fabrication of advanced thermoregulated composite materials. Herein, thermoregulated RPU foams containing silica shelled NanoPCMs were fabricated, in order to improve their thermal energy storage capacity and mitigate the adverse effect of fillers on the morphology and mechanical properties. Chemical composition and morphology of the composite foams were characterized by FT-IR and SEM, respectively. Thermal properties of the composite foams were evaluated by DSC, TGA, and DMTA (dynamic mechanical thermal analysis) methods. The NanoPCMs are homogeneously dispersed in polyurethane matrix. Higher NanoPCMs contents in the composite foams lead to slightly increased cell size, minor decrease of glass transition temperature (Tg), and higher phase change enthalpies. The composite foams exhibit good thermal reliability, reasonable thermoregulation property, and fairly high compressive properties. In addition, the compressive property-density relationship for the composite foams agrees well with the Gibson-Ashby’s power law.

Authors : E. Lust, H. Kurig, M. Russina, M. Siebenbürger, E. Härk, R. Jäger, K. Vaarmets, S. Sepp, T. Thomberg, I. Tallo, A. Jänes, T. Romann
Affiliations : Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia; Helmholtz Zentrum Berlin, 14109 Berlin, Germany

Resume : The structure of nanoporous carbon has a strong effect on the electrochemical characteristics of the devices like supercapacitors, polymer electrolyte fuel cells and electrolysers, Li-ion and Na-ion batteries. For that reason, it is crucial to have a good understanding of the porosity and structure of used carbon materials. As a standard method, the nitrogen adsorption measurements and various analysis theories (e.g Brunauer-Emmett-Teller and non-local density functional theory) are used. However, these models need the pore shape as an input parameter for detailed calculations and often the slit-shaped pore model is assumed without additional verification. This assumption is also very often transferred to the behaviour of carbon materials in different applications leading to some serious misinterpretations. Our research focuses on determining the pore shape and size in three carbide-derived carbon materials using various rather standardized methods, like nitrogen adsorption measurements, Raman spectra analysis etc., combined with small-angle neutrons scattering. The results obtained are compared to the behaviour of these materials in different energy storage/conversion related devices like supercapacitors and polymer electrolyte fuel cells. As a result, the importance of hierarchical porous structure and pore shape along with pore size of used carbon materials in these applications will be addressed and demonstrated.

Authors : Michal Dusza (1, 2), Pawel Gluchowski (1), Filip Granek (2), Wieslaw Strek (1)
Affiliations : (1) Institute of Low Temperature and Structure Research, Polish Academy of Science, Okolna 2, 50-422 Wroclaw, Poland; (2) Wroclaw Research Centre EIT+, Stablowicka 147, 54-066 Wroclaw, Poland

Resume : Dominant technology of fabrication high quality of single layer graphene on large area is Chemical Vapor Deposition (CVD). The best results are obtained for metal substrates (Ni, Ci or MoNi). Much more sophisticated is graphene fabrication on the semiconductor and isulating substrates, which are commonly used in electronic and optoelectronic devices. Technology of graphene transfer on the arbitrary substrates will open wide range of new application. Combining the low-cost metal oxides thin films with single graphene layers allows to obtain multilayer structures with improve optoelectronic properties. Zinc oxide layers were obtained using decomposition of Zn(acac)2 hydrate method. Graphene layer was transferred from the copper foil on the zinc oxide layer by low temperature wet transfer method, using the PMMA as a temporary carrier medium. Etching processes of copper foil and PMMA were optimized to obtain the high quality of graphene on the zinc oxide surface without residuals of PMMA. Presence of graphene on the surface was confirmed using the Raman spectroscopy (2D peak at 2699 cm-1 and G peak at 1592 cm-1). Intensity of 2D peak was two times higher than for G peak. Optical and electrical properties of graphene single layer/ZnO structure were investigated. Combining of the transparent conductive oxide and electron transport layers for potential applications in organic photovoltaics are presented.

Authors : M.P. Gurrola1, E. Ortiz-Ortega2, J. Ledesma-García2, L.G. Arriaga1*
Affiliations : 1 Centro de Investigación y Desarrollo Tecnológico en Electroquímica, Pedro Escobedo, Qro., C.P. 76703, México. 2 Facultad de Ingeniería, División de Investigación y Posgrado, Universidad Autónoma de Querétaro, Centro Universitario Cerro de las Campanas, Querétaro, Qro., C.P. 76010, México

Resume : Burning fossil fuels that are in finite reserves globally triggers problems because of the emission of CO2 and other air pollutants. These issues have stimulated interest in hydrogen as a clean energy source. In these sense, the water electrolysis is a cost-effective method to produce hydrogen and environment-friendly. However, the design of oxygen electrodes is the main limiting factor, so the use of an electrocatalyst support different to conventional carbon support is an important aspect to study of this systems. For this reason, in this work we present the physicochemical and electrochemical characterization of Sb-doped SnO2 (ATO) synthesized by Sol-Gel method and assisted by microwave as a support for H2 production. Morphology, composition, crystallinity and surface area were investigated by SEM, EDS, XRD and BET. The results showed that the ATO has a homogeneous distribution and crystal sizes 5-6 nm with a preferential planes (110) and (101) corresponding to the tetrahedral rutile structure. The electrochemical characterization was evaluated for H2 production at E=1.8 V vs. NHE during 7 days of continuous operation and compared with Vulcan Carbon in a membraneless water microfluidic electrolyzer. The results show improved chemical stability when the ATO is subjected to these conditions, whereas Vulcan Carbon is corroded easily. As a perspective, this system can be integrated with a microfluidic fuel cell to supply energy to low-power devices.

Authors : J. Hulik 1,4, F. Le Normand 1, F. Antoni 1, F. Aweke 1, D. Muller 1, S. Zafeiratos 2, W. Luo 2, P. Pfeiffer 3, P. Veis 4
Affiliations : 1 ICube, MaCEPV, 23 rue du Loess, 67037 Strasbourg, France; 2 ICPEES, ECPM, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France; 3 ICube/IPP, Pôle API, 300, Boulevard Sébastien Brant, 67412 Illkirch, France; 4 Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F1, 84248 Bratislava, Slovakia

Resume : Graphene thin films on Diamond-like carbon (DLC) films have been obtained on transparent substrates like quartz or glass by pulse laser deposition (PLD) of carbon at ambient temperature followed by either thermal annealing performed in Ultra High Vacuum condition up to 1273 K. The surface formation of a graphene-like film on top of the DLC, soon experimentally shown in Appl. Phys. A, Materials Science & Processing, 71, 433–439 (2000), has been investigated as a function of many parameters of the PLD and post-PLD processes (like laser fluence, DLC thickness, annealing temperature). The roughness of the films was find lower than 1 nm set over a rather large surface area. The density of the carbon has been measured both by XPS and Nuclear Reaction Analyses (NRA). The formation of graphene films on top of DLC have been characterized by X-ray photoemission (XPS) and Raman scattering. Under optimized conditions these films can exhibit high surface conductivity, optical transmission and work function performances, so that it can be achieved a high figure of merit (conductivity of transparency) as transparent conductors.

Authors : Zakaria Saadi, Vlad Stolojan, José V. Anguita, and S. Ravi P. Silva
Affiliations : University of Surrey, Advanced Technology Institute

Resume : Thermoelectric (TE) materials are devices capable of converting energy from waste heat into an electrical potential when a temperature gradient is induced between the two ends of a material. The wide application range of TE materials includes the sectors of automotive, wearable electronics and power stations. However, current TE devices are composed of semiconductor materials which tend to be toxic, inorganic and expensive to manufacture such as Bismuth Telluride, thus, making the production of these devices into real-world applications challenging. In this project, carbon nanotubes (CNT) are shown to be an alternative TE material with properties that include mechanical flexibility, low manufacturing cost and non-toxicity. The process of functionalizing CNTs and doping them to n-type and p-type semiconductors is investigated. An efficient TE device should translate to a high figure of merit (ZT) which requires a high power factor and a low thermal conductivity. The latter is investigated and we reveal that nano-defects and phonon scattering in low dimensional structures can result in a low thermal conductivity by the inclusion of various concentrations of Polyethylenimine (PEI) which reduces the phonon mean free path without significantly affecting the power factor. The thermal conductivity of the synthesised CNT/PEI composites were measured and calculated to be as low as 20 W/mK at a temperature of 50°C.

Authors : Sandeep Kumar,a,b M. Thirumal,b Ashok K. Ganguli,a,c
Affiliations : a. Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India b. Department of Chemistry, University of Delhi, Delhi 110007, India c. Institute of Nano Science & Technology, Habitat Centre, Phase- X, Sector – 64, Mohali, Punjab – 160062, India

Resume : An outstanding challenge in the realm of photocatalysis is the development of nanomaterials functional under visible region; to tackle the present plight of environment. Our work unfolds the design of core/shell nanostructures manifesting an appreciable photoelectrochemical water splitting and photocatalytic degradation of methylene blue, a noxious organic pollutant of dye waste water under visible light. Using core/shell geometry and the apposite sensitizer, we have tuned the absorption of NaNbO3 nanostructures to the visible region. The NaNbO3 core/shell nanostructures with the expanded light harvesting range are utilized for the destructive oxidation of noxious organic pollutants with the goal to ameliorate the environment. The remarkably enhanced photocatalytic activity of core/shell nanostructures could be interpreted in terms of efficient charge separation owing to core/shell geometry and resulting type-II band alignment between NaNbO3 and the sensitizer, which creates a step-like radial potential favoring the localization of one of the carriers in the core and the other in the shell.1 Our work unfolds the importance of core/shell nanostructures in leading toward new paradigms for developing highly efficient and reusable photocatalysts for the mitigation of noxious organic pollutants. Keywords: Photocatalysis, core/shell, NaNbO3, type-II band alignment, sensitizer 1. Kumar, S.; Singh, A. P.; Bera, C.; Thirumal, M.; Mehta, B. R.; Ganguli, A. K. Visible Light Driven Photoelectrochemical and Photocatalytic Performance of NaNbO3/Ag2S Core/Shell Heterostructure ChemSusChem, 2016 (Accepted)

Authors : T.-P. Fellinger*, Yuanqin Chang, Jonas Pampel and Markus Antonietti
Affiliations : Max Planck Institute of Colloids and Interfaces, Potsdam/Germany

Resume : Porous carbon materials are known for their applicability in important areas such as electrochemistry (e.g. fuel cell catalysts, where a lot of interest aroused due to possible coupling of advantageous structural properties and unique chemistry. The preparation of high content doped and conductive graphitic carbons can be achieved e.g. by employing ionic liquids (ILs) as precursors. We and others have shown that mesoporous carbon with structurally integrated nitrogen acts as an inexpensive and highly active metal-free catalyst in the oxygen reduction reaction (ORR).[1-3] A key-drawback was still the necessity of using silica templates and their hazardous removal to obtain porous high surface area materials. Our recent research focuses first on the porosity development in alternative fashion and second on the employment of naturally abundant carbon precursors, both for the perspective of large scale synthesis.[4, 5] Materials with very high surface areas and total pore volumes are accessible using alternative templates and molten salt syntheses and even completely new carbon morphologies are obtained throughout a carbonization from the wet state.[6, 7] The performance as non-noble electrocatalysts for the oxygen reduction reaction and the role of porosity will be discussed [1] W. Yang, T.-P. Fellinger, M. Antonietti, J. Am. Chem. Soc. 2011, 133, 206. [2] R. Liu, D. Wu, X. Feng, K. Müllen, Angew. Chem. Int. Ed. 2010, 49, 2565. [3] T.-P. Fellinger, F. Hasché, P. Strasser, M. Antonietti, J. Am. Chem. Soc. 2012, 134, 4072-4075. [4] N. Fechler, T.-P. Fellinger, M. Antonietti, Adv. Mater. 2013, 25, 75-79. [5] K. Elumeeva, N. Fechler, T.-P. Fellinger, M. Antonietti, Mater. Hor. 2014, 1, 588-594. [6] Y. Chang, M. Antonietti, T.-P. Fellinger, Angew. Chem. 2015, 54, 5507-5512. [7] J. Zhu, K. Sakaushi, G. Clavel, M. Shalom, M. Antonietti, T.-P. Fellinger, J. Am. Chem. Soc. 2015, 137, 5480-5485.

Authors : Dickon Ng, Jia Li
Affiliations : Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China; School of Material Science and Engineering, University of Jinan, Jinan, China

Resume : With the rapid growth of industrialization, huge amounts of dye effluents are often disposed into the environment causing significant pollution in water. Microwave (MW) irradiation in water treatment has gained attention due to its rapid and selective heating of materials. In this study, we have developed a two-step method involving impregnation and calcinations processes for the controllable synthesis of a porous Cu-Ni/C catalyst by using organic tissue paper as template. The sample was mesoporous and it exhibited macoporous networks composing of interwoven carbon fibers loaded with Cu-Ni nano-particles. The surface area of the sample was determined to be 538 m2/g. The product also exhibited high catalytic activity in the degradation of acid fuchsin dye during the microwave induced catalytic oxidation (MWICO) process. The degradation of acid fuchsin was a fast process under MW irritation. Not only in the chromophore group, but the naphthalene ring and benzene ring could also be destroyed. The presence of Ni had a significant effect on the degradation because it enhanced the formation of the hydroxyl radicals (•OH) under MW irritation. This outcome is important, not only because a hierarchically porous catalyst with high active sites has been developed using a simple bio-template route, it advanced the understanding of the roles of transition metals and activated carbon in dye degradation in water treatment under electromagnetic wave irradiation.

Authors : Gabriel Casano, Yue Lin, Suelen Barg, Ian Kinloch, Brian Derby.
Affiliations : School of Materials, University of Manchester; Cambridge Graphene Centre, University of Cambridge; School of Materials, University of Manchester; School of Materials, University of Manchester; School of Materials, University of Manchester.

Resume : Graphene is a promising material for supercapacitor applications, both in electric double layer capacitors and as a conductive support for incorporating materials with large pseudocapacitance. Aerogels represent an attractive way to fabricate 3D graphene structures with large and accessible specific surface area suitable for supercapacitor electrodes. Freeze casting is a versatile route for aerogel fabrication that is scalable and has a relatively low production cost. However, most prior work on freeze casting graphene aerogels used graphene oxide (GO) as the source material because of the need to disperse it in water prior to freezing and vacuum sublimation. The resulting GO aerogel must be reduced to form the electrically conductive reduced graphene oxide (rGO) before it can be used as an electrode. Here we present a method to fabricate pristine graphene aerogels for supercapacitors using phenol as a room temperature sublimeable vehicle, without the need for a reduction step. These materials have electrical conductivity values reaching 0.9 S/cm, which is greater than equivalent rGO aerogels with similar densities produced by aqueous freeze casting. Alternative solvent systems have been identified using a solubility parameter approach and examples of aerogels fabricated with these materials that are more suitable for larger scale manufacture will be presented.

Authors : S. Valdueza-Felip, A. Mukhtarova, L. Redaelli, A. Ajay, E. Bellet-Amalric, S. Pouget, C. Durand, J. Eymery, A. Núñez-Cascajero, C. Bougerol, M.-P. Chauvat, P. Ruterana, K. Lorenz, E. Alves, L. Grenet, E. Sarigiannidou and E. Monroy
Affiliations : University Grenoble Alpes, 38000 Grenoble, France; CEA-Grenoble, INAC, 17 av. des Martyrs, 38000 Grenoble, France; University of Alcalá, Mdr-Bcn Road km 33.6, 28871 Alcalá de Henares, Spain; CNRS-Institut Néel, 17 av. des Martyrs, 38000 Grenoble, France; CIMAP, CNRS-ENSICAEN-CEA-UCBN, 6 Blvd. Maréchal Juin, 14050 Caen, France; IPFN-IST-CTN, Estrada Nacional 10, P-2695-066, Bobadela LRS, Portugal; CEA-Grenoble, LITEN, 17 av. des Martyrs, 38000 Grenoble, France; INP-Minatec, 17 av. des Martyrs, 38000 Grenoble, France

Resume : InGaN alloys are promising semiconductors for hybrid tandem solar cells due to their tuneable direct bandgap within the visible spectrum. Best solar cell efficiencies are obtained in structures grown by metalorganic vapour phase epitaxy (MOVPE) with active regions including InGaN/GaN multiple quantum-wells (MQWs). However, to further improve the photovoltaic characteristics the In content should be increased, being then the plasma-assisted molecular beam epitaxy (PAMBE) the most suitable growth technique. In this work we present results on solar cells based on InGaN/GaN MQWs grown by MOVPE and In-rich InGaN junctions grown by PAMBE. The design of the active region including QW, barrier and total thicknesses, and In mole fraction is critical for the success of the solar cells. We investigate the dependence of the photovoltaic performance on these parameters to limit the strain relaxation and the formation of structural defects while improving the conversion efficiency. Regarding In-rich InGaN devices, the PAMBE growth mechanisms that control the strain relaxation and In incorporation in thick layers is discussed. We demonstrate that the presence of Mg does not disturb the In incorporation and leads to a reduction of the stacking fault density in p-doped InGaN. The electrical characterization of p-i-n InxGa1-xN homojunctions (x = 0.10.4) is presented, which peak external quantum efficiency is 14±2% in the blue-to-orange spectral region with a cut-off from 465 nm to 600 nm.

Authors : D. Pontiroli, D. D'Alessio, M. Gaboardi, G. Magnani, M. Riccò, C. Milanese, S. G. Duyker, V. K. Peterson, N. Sharma
Affiliations : Carbon Nanostructures Lab, Department of Physics and Earth Sciences, University of Parma, Parma, Italy; Pavia Hydrogen Lab, C.S.G.I. & Chemistry Department, University of Pavia, Pavia, Italy; The Bragg Institute, Australian Nuclear Science and Technology Organisation, Kirrawee DC, Australia; School of Chemistry, University of New South Wales (UNSW), Sydney, Australia

Resume : Ammonia has been proposed as an efficient indirect hydrogen carrier, as it contains a large fraction of H2 (up to 18 wt% in liquid NH3) and it can be directly used as a fuel in SOFCs to produce energy, without greenhouse emissions. Nowadays, infrastructure for NH3 production, handling and transportation are well-established and developed, but the identification of a system for solid-state ammonia-storage would allow to further reduce hazards at a level below those of gasoline. Here we investigated the ability of lithium intercalated fullerides LixC60 (x = 3, 6, 12) to absorb large amount of ammonia, forming novel hyper-ammoniated phases, by letting react the fulleride with liquid NH3 at low T. The ammonia release from these compounds was investigated using high intensity neutron powder diffraction, in-situ/ex-situ manometric analyses and differential scanning calorimetry. We found that in (ND3)yLixC60 ammonia molecules are stored in their neutral state inside the inter-fullerene interstices and are coordinated to the intercalated Li ions, forming Li–ND3 clusters. In particular, Li6C60 was found to absorb up to 36.8 wt% ND3, corresponding to 14 ammonia molecules per C60. Ammonia desorption takes place in two main steps, at 350–410 K and 500–540 K, respectively, corresponding to two clear 1st order structural phase transitions, and absorption process is partially reversible. These findings suggest that these systems could be good candidates for ammonia-storage applications.

Authors : Rui P. P. L. Ribeiro, Bárbara C. R. Camacho, Andriy Lyubchyk, Isabel A. A. C. Esteves, Fernando J. A. L. Cruz, Jose P. B. Mota
Affiliations : LAQV-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal (R. Ribeiro, B. Camacho, I. Esteves, F. Cruz, J. Mota); CEMOP-UNINOVA, CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal (A. Lyubchyk)

Resume : The adsorption equilibria of ethane (C2H6) and ethylene (C2H4) in the MIL-53(Al) metal organic framework are characterized using a self-consistent procedure combining experimental measurements and molecular simulation. Experimental single-component adsorption equilibrium data for C2H6 at 303 K, 323 K, 353 K, and 0–8 bar, and for C2H4 at 323 K, 353 K, 373 K, and 0–1.7 bar, are successfully interpreted using classical thermodynamics and statistical mechanics. An analysis of the experimental results shows that the large-pore form of the tested MIL-53(Al) sample is thermodynamically favoured in the pressure and temperature ranges spanned in the experiments. The adsorption equilibria of the two adsorbates are studied is detail by Monte Carlo (MC) simulation in the Canonical (NVT) and Grand-Canonical (GC) ensembles using the TraPPE united-atom force field to describe both the fluid–fluid and solid–fluid interactions. The good agreement between the GCMC results and experimental measurements shows that the adopted force field provides a good description of the dispersive solid–fluid interactions in MIL-53(Al). The molecular configuration of the confined ethylene molecules at different loadings is studied in the NVT ensemble and the preferential positions and orientations of the C2H4 molecules are determined. Binary C2H6/C2H4 adsorption equilibrium in the pressure and temperature ranges of the single-component experiments is predicted by GCMC using the validated force field. The ideal behaviour of the binary adsorbed mixture is demonstrated using the Ideal Adsorbed Solution Theory (IAST) and the multicomponent extension of the Toth isotherm model.


Symposium organizers
Aadesh PRATAP SINGHIndian Institute of Technology, Delhi

Hauz Khas, New Delhi 110016, India
Joanna K. BENDYNAMintres B.V.

De Nieuwe Erven 8 5431 NT Cuijk, The Netherlands
Rajeev AHUJA (Main Organizer)Department of Physics and Astronomy, Uppsala University

Box-516 SE-75120 Uppsala, Sweden
Sudip CHAKRABORTYApplied Materials Physics, Royal Institute of Technology (KTH) Stockholm

SE-10044 Stockholm, Sweden