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Materials for a sustainable transition


Modelling and characterization of novel functional materials for green energy, sensing, and catalysis applications

This symposium covers:
(i) Materials Theory and Methods: Recent advances in molecular dynamics, multi-scale models, statistical / machine learning-based studies, time-dependent processes.
(ii) Materials Characterization: Advanced characterization techniques
(iii) Applications: Nanophotonics, nanoelectronics, catalysis, energy, sensing


Various theoretical and computational methods have been developed and utilized to understand and design novel functional materials and nanostructures in the past years, revealing several fascinating physical effects with diverse potential technological applications.

This symposium aims to gather scientists developing and combining various theoretical, computational, and experimental characterization approaches to study and design functional materials for their potential in green energy, sensing and catalysis applications. It addresses researchers from computational and experimental materials science and engineering, condensed matter physics, quantum chemistry, applied mathematics and high-performance scientific computing. We encourage abstracts in the areas of methodology development and material applications. The materials theory and methods category includes the modelling from ab initio methods (e.g., quantum chemistry, density functional theory (DFT), time-dependent DFT and non-adiabatic molecular dynamics), semi-classical and classical approaches (and their combinations with quantum approaches), machine-learning assisted approaches, etc. The structure modelling includes bulk semiconductors, transition metals and transparent conducting oxides, polymers and perovskites, thermoelectrics, low dimensional materials (carbon nanotubes, graphene, transition metal dichalcogenides and other nanoflakes and single-molecule films). Physical processes involving coupled-electron-ion dynamics will be covered, going beyond the Born-Oppenheimer approximation.

The materials characterization category includes the latest developments in the synthesis and characterization of nanomaterials (such as nanocrystals, nanoparticles, thin films) whose combined physical and chemical properties foster clean energy production, conversion and storage, sensing and catalysis. In particular, contributions dealing with self-assembly approaches, characterization methodologies, applications of structurally and/or chemically functional-designed nanomaterials combined with computational approaches.

Hot topics to be covered by the symposium:

  • Coupled electron-ion dynamics
  • High-harmonic generation
  • Dynamics of the excited state
  • Excitons in van der Waals heterostructures
  • Many-body perturbation theory
  • Multiscale and machine learning approaches
  • Combinations of different nanomaterial classes in rationale-designed nanocomposites
  • Cutting-edge characterization techniques for morphological, structural, compositional, optical, and electrical nanostructure properties
  • Nanomaterials for
    - energy production, conversion, and storage
    - hydrogen energy
    - sensing (optical and chemoresistive)
    - plasmonic solar cells and catalysis
    - new generation batteries, fuel cells and thermoelectrics

List of invited speakers (confirmed):

  • Abhishek Mishra, University of Petroleum and Energy Studies, India
  • Andrea Marini, National Research Council, Italy
  • Anurag Srivastava, ABV-Indian Institute of Information Technology and Management, India
  • Chawki Awada, King Faisal University, Saudi Arabia 
  • Chiara Milanese, Università di Pavia, Italy
  • Hemant Kumar Kashyap, Indian Institute of Technology Delhi, India
  • Isodiana Crupi, Universit di Palermo, India
  • Katarzyna Grochowska, Polish Academy of Sciences, Poland 
  • Mariachiara Pastore, CNRS & Université de Lorraine, France
  • Matthieu J Verstraete, Université de Liège, Belgium 
  • Piotr Kowalski, Forschungszentrum Juelich GmbH, Germany
  • Pooja Goddard, Loughborough University, UK
  • Rosaria Anna Puglisi, Consiglio Nazionale delle Ricerche (CNR), Italy
  • Sanjai Singh, Indian Institute of Information Technology-Allahabad, India
  • Søren Peder Madsen, Aarhus University, Denmark


Call for papers – Invitation to authors

E-MRS 2022 Fall Meeting Symposium N: Special Issue in physica status solidi (b)

Modelling and characterization of novel functional materials for green energy, sensing, and catalysis applications

Guest Editors

Jost Adam, Francesco Ruffino, Biplab Sanyal, and Sangeeta Sharma

Submission Deadline: November 30th, 2022

Submission at

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Modelling and characterization of novel functional materials – E-MRS Fall 2022 Symp N


Dear E-MRS 2022 presenters,

Related to the forthcoming Symposium N of the E-MRS 2022 Fall Meeting it is planned to publish a special issue in pss (b) – basic solid state physics. These will follow the established tradition of similar symposia publications in our journal see (

In collaboration with the Guest Editors, the Meeting Organizers and the pss Editorial Office we cordially invite you to contribute a Research Article based on your oral or poster presentation. Invited speakers will have the opportunity to submit Review Articles.

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Moreover, pss (b) is a hybrid Open Access (OA)/subscription journal. The Open Access option is compliant with national or funder mandates, supported by an ever increasing number of countries and institutions. For details see Wiley Author Services and contact us with questions.

Please refer to the guidelines received from the symposium organizers and the author instructions available on our homepage ® Author Guidelines (including Word template and LaTeX style files and the link to online submission through Editorial Manager). You should mention the symposium in your cover letter and select the appropriate topical section/category Modelling and characterization of novel functional materials – E-MRS Fall 2022 Symp N during online submission to expedite handling.

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Jost Adam, Francesco Ruffino, Biplab Sanyal, and Sangeeta Sharma (Guest Editors) and Stefan Hildebrandt (pss Editor-in-Chief)


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Materials for Energy Conversion I : B. Sanyal, J. Adam
Authors : Andrea Marini
Affiliations : Istituto di Struttura della Materia, National Research Council, Italy

Resume : The concept of optical exciton, a photo-excited bound electron-hole pair within a crystal, is routinely used to interpret and model a wealth of excited-state phenomena in semiconductors. Beside originating sub-band gap signatures in optical spectra, optical excitons have also been predicted to condensate, diffuse, recombine, relax. However, all these phenomena are rooted on a theoretical definition of the excitonic state based on the following simple picture: “excitons” are actual particles that both appear as peaks in the linear absorption spectrum and also behave as well-defined quasiparticles. In this work we show, instead, that the electron-phonon interaction decomposes the initial optical (i.e., “reducible”) excitons into elemental (i.e., “irreducible”) excitons, the latter being a different kind of bound electron-hole pairs lacking the effect caused by the induced, classical, electric field. This is demonstrated within a real-time, many-body perturbation theory approach starting from the interacting electronic Hamiltonian including both electron--phonon and electron-hole interactions. We then apply the results on two realistic and paradigmatic systems, monolayer MoS$_2$ (where the lowest--bound \opte is optically inactive) and monolayer MoSe2 (where it is optically active), using first-principles methods to compute the exciton-phonon coupling matrix elements. Among the consequences of optical-elemental decomposition, we point to a homogeneous broadening of absorption peaks occurring even for the lowest-bound \opte, and we provide a lower bound for the exciton linewidths. More generally, our findings suggest that the optical excitons gradually lose their initial structure and evolve as elemental excitons. These states can be regarded as the real intrinsic excitations of the interacting system, the ones that survive when the external perturbation and the induced electric fields have vanished.

Authors : Pooja Goddard*, Peter Hatton, Michael J. Watts, John M. Walls, Ali Abbas, Roger Smith
Affiliations : Department of Chemistry, Loughborough University

Resume : The conversion efficiency of as-deposited, CdTe solar cells is poor and typically less than 5%. A CdCl2 activation treatment increases this to up to 22%. Studies have shown that stacking faults (SFs) are removed and the grain boundaries (GBs) are decorated with chlorine. Thus, SF removal and device efficiency are strongly correlated but whether this is direct or indirect has not been established. Here we explain [1] the passivation responsible for the increase in efficiency but also crucially elucidate the associated SF removal mechanism [2]. The effect of chlorine on a model system containing a SF and two GBs is investigated using density functional theory. The proposed SF removal mechanisms are feasible at the 400oC treatment temperature. It is concluded that the efficiency increase is due to electronic effects in the GBs while SF removal is a by-product of the saturation of the GB with chlorine but is a key signal that sufficient chlorine is present for passivation to occur. [1] Watts et al., Phys. Rev. Materials, 2021, 5(3), 035403 [2] Hatton et al, Nature Communications, 2021, 12(1), 4938

Authors : Miquel Casademont-Viñas a, Martí Gibert-Roca a, Quan Liu b, Koen Vandewal b, Alejandro R. Goñi a, c, Mariano Campoy-Quiles a.
Affiliations : a Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Spain, Campus UAB, Bellaterra, Spain b U Hasselt – Hasselt University, Institute for Materials Research (IMO-IMOMEC), BE, Agoralaan – Building D, Diepenbeek, Belgium c Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluïs Companys, 23, 08010, Barcelona, Spain

Resume : Single-junction organic solar cells (OSC) nowadays reach a power conversion efficiency of 19%.[1] In principle, multi-junction devices promise a reduction of thermalization losses and thus higher efficiencies. Nevertheless, state-of-the-art multi-junction OSC, leaded by the tandem approach in which two single junction devices are stacked on top of each other, exhibit, thus far, similar efficiency values.[2] This is attributed to the challenges that arise when solution processing stackable layers, as well as the need for either a current matching or an extra transparent electrode.[2] In this talk, we will present a new multi-junction in-plane spectral splitting geometry that we call Rainbow solar cells. In this geometry, a series of sub-cells are placed next to each other laterally, avoiding the limitations arising from stacking cells in a vertical tandem. The fabricated n-terminal devices are capable of extracting the maximum power of each sub-cell without the need for any current matching. First, we will present the advantages and disadvantages of Rainbow OSCs with respect to other organic and inorganic multi-junction approaches. Then, we use device simulations to provide design rules for increased efficiency in a Rainbow configuration. Finally experimental results are shown for different organic blends, as high and low band-gap sub-cells. The results, in agreement with simulations, demonstrate that an increase of around 40% with respect to the best single junction device can be achieved with the Rainbow geometry. References: [1] Cui, Y., Xu, Y., Yao, H., Bi, P., Hong, L., Zhang, J., Zu, Y., Zhang, T., Qin, J., Ren, J., Chen, Z., He, C., Hao, X., Wei, Z., Hou, J., Single-Junction Organic Photovoltaic Cell with 19% Efficiency. Adv. Mater. [2] Di Carlo Rasi, D., Janssen, R. A. J., Adv. Mater. 2019, 31, 1806499.

Authors : Léo Choubrac, Eugène Berlin, Nicolas Barreau
Affiliations : Nantes Université, CNRS, Institut des matériaux de Nantes Jean Rouxel, IMN, F-44000 Nantes, France

Resume : Despite recent advances, the efficiency gap between copper-indium-gallium sulfide (CIGS) and selenide (CIGSe) solar cells efficiency remains significant (16 vs 23%) due to the higher open-circuit voltages(VOC) losses. Two phenomena are involved in those losses: interface and bulk recombinations. The severity of each loss depends on the composition, the structure, and the optoelectronic properties of the CIGS phase as well as on the presence of secondary phases. The bandgap value is primarily determined by the In/Ga ratio and thus is easily set to an optimum ≈1.65 eV value. Hence, the remaining key factors are related to the Cu content and the synthesis parameters. In particular, a key to achieving high-efficiency selenide cells is known to be a well-designed alkali (especially Na) supply, which is known to affect grains growth, the formation of secondary phases, and suppresses the formation of a VOC-killer electronical defect. To speed up the investigation of the role of Cu content and Na-supply while avoiding problems related to process reproducibility, we embarked on a combinatorial study of CIGS material and solar cells. CIGS layers were synthesized via co-evaporation with a tilted Cu-source resulting in a lateral Cu-gradient of about 20%(max to min). From a single deposition, we then obtain a series of 84 samples with varying Cu content. Na-supply is controlled by substrate nature (Na-free or not) as well as NaF evaporation at different stages of the process. After calibration with EDX and XRD, the composition and phases present in each sample are determined by Raman spectroscopy and intrinsic bulk properties (related to bulk recombination) by photoluminescence. Solar cells are finally prepared and characterized using IV and EQE, which provides us experimental VOC and allows us to analyze interface losses. Stability over time and illumination was investigated as well. The key parameters of all produced samples (>500) are finally compiled in a database which enables us to shine light on the role of Cu and Na on phases formation, optoelectronic properties, and ultimately devices performance and stability.

Authors : Ivona Kafedjiska, Vincent M. Le Corre, Rutger Schlatmann, Iver Lauermann
Affiliations : Helmholtz-Zentrum Berlin (HZB), Competence Centre Photovoltaics (PVcomB), Berlin, Germany; University of Erlangen-Nuremberg (Friedrich-Alexander-Universität Erlangen-Nürnberg), Erlangen, Germany; Helmholtz-Zentrum Berlin (HZB), Competence Centre Photovoltaics (PVcomB), Berlin, Germany and Faculty 1 - Energy and Information, Hochschule für Technik und Wirtschaft Berlin, Germany; Helmholtz-Zentrum Berlin (HZB), Competence Centre Photovoltaics (PVcomB), Berlin, Germany.

Resume : We simulate experimentally-measured JV curves of fresh and 14-days aged p-i-n single-junction perovskite solar cells with four hole-transporting layers (HTLs): NiOx, NiOx:Cu, NiOx+SAM, and NiOx:Cu+SAM, where SAM was the MeO-2PACz self-assembled monolayer. The aging is performed in a N2 environment, at 25 C, and under constant illumination. During the aging period, a JV curve is measured every 24 hours. The simulation is performed via a coupled ion and steady-state drift-diffusion model at open-circuit conditions. The model considers experimentally measured values like VBM, mobility, and thickness of the HTL and varies only the concentration of ions and numbers of surface traps on the HTL-perovskite interface. By comparing the simulated and experimentally-measured JV curves of both the fresh and the aged cells, we analyze the band alignment, the QFLS-Voc offset, the density of interface and bulk traps, and the recombination rates and current densities for both the fresh and the aged cells. We find that NiOx has a poor energy alignment to the perovskite, yielding a non-negligible QFLS-Voc offset. Additionally, NiOx exhibits strong trapping of electrons and increased Shockley-Read-Hall (SRH) recombination at the NiOx-perovskite interface, as also confirmed by transient surface photovoltage (tr-SPV) measurements. As the cells with NiOx age, the bulk trap density and the bulk SRH recombination current density increase by a factor of 35 and 10, respectively, resulting in a 15% loss in PCE as the cells age. NiOx:Cu, NiOx+ SAM, and NiOx:Cu+ SAM all improve the band alignment at the NiOx-perovskite interface, yielding a Voc of 1.12 V. These three HTLs also suppress the NiOx’s trapping of electrons at the NiOx-perovskite interface, and exhibit a less pronounced increase in the bulk trap density as the cells age. This also translates into more stable devices, with NiOx:Cu maintaining >92%, and NiOx(:Cu)+SAM maintaining around 88% of their initial PCE. One possible reason for the more pronounced degradation of the NiOx could be a 2-5 times higher ion concentration compared to the remaining HTLs. Therefore, the degradation of the NiOx-based cells is most likely amplified by the ions migration into the bulk of the perovskite absorber, causing an increase in the bulk trap density and bulk trap-assisted recombination. According to literature, the mobile ions are most likely I- ions from the PbI2 contribution in the perovskite absorber. In conclusion, this modeling of the solar cells aims at providing a deeper understanding of the influence of the HTL not only on the performance of the solar cells, but also on the ions, interface and bulk traps, and recombination mechanisms that affect the stability of the perovskite solar cells. As such, they provide valuable insight how to fine-tune the HTL-perovskite interface and obtain superior solar-cell performance and stability, both of which are of paramount importance for the future upscaling of the solar cells.

11:00 Coffee Break    
Advanced Characterization I : J. Adam
Authors : V. Iacono (1,2), L. Bruno (1,2), E. Bruno (1,2), F. Ruffino (1,2), S. Mirabella (1,2)
Affiliations : (1) Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, via S. Sofia 64, 95123 Catania, Italy; (2) CNR-IMM (Catania Università), via S. Sofia 64, 95123 Catania, Italy;

Resume : Today, achieving a sustainable energy supply is very challenging. Water splitting can be a scalable solution; however, still critical materials are typically used as catalysts. In particular, highly efficient oxygen evolution reaction (OER) is achieved with Ir and Ru based catalysis [1]. Transition metals (e.g. Ni, Fe) have been attracted lot of attention due to their natural abundance, low cost and good chemical stability. Among them, Ni-based nanostructures have shown excellent catalytic performance for OER. Typically, Ni-based structures are synthesized by harsh chemical methods (hydrothermal, solvothermal). Here we present the catalytic performance of Ni/Ni(OH)2 nanoparticles (NP) obtained by pulsed laser ablation in liquid (PLAL) with a nanosecond pulsed Nd:YAG laser using the fundamental wavelength . A large amount of NP is produced in few minutes of ablation. The NPs morphological and compositional properties have been analysed by Scanning Electron Microscopy, Energy Dispersive X-ray techniques, Rutherford Backscattering Spectrometry, X-Ray Diffraction analysis and X-Ray Photoelectron Spectroscopy. We tested anodes fabricated through drop-casting and spin coating of Ni-based NP onto graphene paper (GP) substrate. Rutherford Backscattering Spectrometry measurements have been performed in order to evaluate the catalyst loading and the distribution of the catalyst over the substrate. The OER features were tested via electrochemical techniques (cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy) under alkaline conditions (1 M KOH). An overpotential of 311 mV at 10 mA cm−2 was measured with a Tafel slope of 43 mV dec−1. Also, the highest Turn Over Frequency (TOF) value was of 2.4 s-1 at the overpotential for lower mass loaded sample spin-coated. These results are promising for the fabrication of low-cost Ni-based nanostructures for high-efficiency and sustainable electrocatalysts. [1] J. Kibsgaard, I. Chorkendorff, Considerations for the scaling-up of water splitting catalysts, Nature Energy 2019, 4, 430.

Authors : Ioannis Kochylas, Anastasios Dimitriou, Maria-Christina Skoulikidou, Lampros Patsiouras, Maria-Athina Apostolaki, Georgia Geka, Anastasia Kanioura, Panagiota Petrou, Nikolaos. Papanikolaou, Vlassis Likodimos, Spiros Gardelis
Affiliations : Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 15 784, Greece; Institute of Nanoscience and Nanotechnology, National Center for Scientific Research ?Demokritos?, 15341 Aghia Paraskevi, Athens, Greece; Institute of Nuclear & Radiological Sciences & Technology, Safety & Energy, National Center for Scientific Research ?Demokritos?,15341 Agia Paraskevi, Athens, Greece

Resume : Surface-Enhanced Raman scattering (SERS) is a technique commonly used nowadays in which inelastic scattering by molecules is significantly enhanced when molecules are absorbed onto metallic nanostructured surfaces such as silver or gold nanoparticles. It is a well-proven powerful technique for quantifying and detecting biological, chemical and other analytes. Silicon nanowires (SiNWs) can produce 3D surfaces and thus offer a high surface-to-volume ratio with various different applications in photonics. In the present work, SiNWs were developed by the metal-assisted chemical etching (MACE) technique and were decorated with silver nanoparticles in order to explore their potential as active substrates for sensitive molecule detection by SERS taking advantage of the excitation of localized surface plasmons that lead to significantly high enhancement factors. Selecting the proper laser excitation wavelength and the type of the metal nanoparticles is of great importance as they could determine the optimal enhancement of the Raman signal as the plasmonic resonance should overlap with the laser wavelength. The performance of our active substrates was evaluated through SERS measurements using Rhodamine 6G (R6G) and Crystal Violet (CV) as probe analytes in a self-constructed Raman spectroscopy experimental set up that has the ability to perform measurements by selecting between two lasers colors (green -532 nm and red- 660 nm) for excitation. The exciting laser is focused by an objective lens and the various analyte Raman lines were collected and separated with a monochromator and a CCD camera. The substrates can produce strong SERS, allowing the detection of analytes even at low concentrations. With the use of a multivariate calibration method based on Principal Components Analysis (PCA) and Hybrid Least Squares (HLS) algorithm, the analysis of the measured Raman spectra and the prediction of the analyte concentration is also possible. Our results show that the Ag decorated Si nanowire substrates fabricated with MACE offer a very promising SERS substrate that can be used for the detection of different analytes. References: [1] I. Kochylas, S. Gardelis,V. Likodimos, K.P. Giannakopoulos, P. Falaras, A.G. Nassiopoulou,Nanomaterials 11 (2021) 1760. [2]Q. Fu, D. Zhang, Y. Chen, X. Wang, L. Han, L. Zhu, P. Wang, H. Ming, Appl. Phys. Let. 103 (2013) 041122. [3]D. Van de Sompel, E. Garai, C. Zavaleta, S. Sam Gambhir, PLoS ONE 7 (2012) e38850

Authors : Jon Serrano-Sevillano1, Marine Reynaud1, Montse Casas-Cabanas1,2
Affiliations : 1.Centro de Investigación Cooperativa de Energías Alternativas (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Parque Tecnológico de Alava, Albert Einstein 48, 01510 Vitoria-Gasteiz, España; 2. IKERBASQUE, Basque Foundation for Science, María Díaz de Haro 3, 48013, Bilbao, Spain

Resume : Defects usually play an important role in the physicochemical properties of materials but faulted structures are often challenging to characterize. Stacking faults can eventually be detected with HR-STEM images, but as it is a local technique, it is not easy to extrapolate it to the bulk. In contrast, XRD offers an average general overview of the structure, so extracting information from the XRD patterns can give a more accurate description of the structure. However, the models used in most of the characterization techniques commonly reproduce ideal structures, so if the real model is far from the ideal one due to a large amount of stacking faults, the refinement results can be poor. Consequently, these are often ignored from the structural characterization, which can lead to a misunderstanding of the structure-properties correlations. In this work, the structural characterization of a series of faulted materials is presented. 1,2 HR-STEM images have detected stacking faults in all the samples, which have an impact on their XRD patterns. For an accurate description of the structure, the information from the XRD patterns has been extracted using the FAULTS software. 3,4 This software builds the structure using a set of layers and stacking vectors and probabilities, meaning that stacking faults can be included in the representation and refined. The information obtained from these refinements has been used to correlate the structure with the electrochemical performance. 1- H. Zhang, B. et al., Chem. Mater., 2018, 30, 692–699. 2- J. Serrano-Sevillano, et al., Phys. Chem. Chem. Phys., 2018, 20, 23112–23122. 3- M. Casas-Cabanas, et al., Zeitschrift fur Krist. Suppl., 2006, 1, 243–248. 4- M. Casas-Cabanas, et al. Appl. Crystallogr., 2016, 49, 2259–2269.

Authors : Deepti Raj (a), Gabriele Barrera (b), Federica Celegato (b), Aliona Nicolenco (c), Federico Scaglione (a), Jordi Sort (c,d), Eva Pellicer (c), Paola Tiberto (b), Paola Rizzi (a)
Affiliations : (a) Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125 Torino, Italy; (b) Istituto Nazionale di Ricerca Metrologica (INRIM), Str. delle Cacce 91, 10135 Torino, Italy; (c) Universitat Autònoma de Barcelona, Campus de la UAB, Plaça Cívica, 08193, Bellaterra, Barcelona, Spain; (d) ICREA, Pg. Lluís Companys 23, E-08010 Barcelona, Spain

Resume : Successful fabrication of dense and mesoporous FePd nanowires (NWs) of different diameters and compositions (ranging from Fe29Pd71 to Fe60Pd40) has been achieved employing template- and micelle-assisted pulsed potentiostatic electrodeposition method. The NWs were electrodeposited into nanoporous anodic alumina (AAO) and polycarbonate (PC) templates of varying pore sizes. An FePd electrolyte was utilized to obtain dense NWs while in the case of mesoporous NWs a block copolymer, P123, was added to this electrolyte as the micelle-forming surfactant. The as-prepared NWs possess a face-centered cubic structure exhibiting a range of length, from 3.1 µm to 7.1 µm. PC-derived dense NWs are longer and more continuous compared to their AAO-derived counterparts. The mesoporous NWs have a Pd-rich composition and reveal a core-shell structure where the porosity is only witnessed in the internal volume of the nanowire while the outer surface remains solid and non-porous. At more negative potentials Fe incorporation was favoured and some dependence of composition on pore size was also observed. Then, the NWs partially embedded in the AAO template were examined as active substrates for Surface-enhanced Raman Spectroscopy (SERS). Strong SERS effect has been displayed by the NWs for 4,4?-bipyridine probe molecule credited to the presence of multiple hotspots. Impressively low detection limit of < 10-12 M has also been recorded. Hence, the excellent SERS performance of the reported NWs holds remarkable promise for their application in the field of life science and ultrasensitive instrumentation.

Authors : Jose M. Sojo-Gordillo, P. Olivier Chapuis, Séverine Gomes, Alex Morata, Albert Tarancón
Affiliations : Catalonia Institute for Energy Research (IREC), Jardins de Les Dones de Negre 1, 08930, Sant Adrià de Besòs, Barcelona, Spain Centre for Energy and Thermal Sciences of Lyon (CETHIL), CNRS-INSA Lyon-UCBL, Villeurbanne, France Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010, Barcelona, Spain

Resume : Currently employed materials in Thermoelectric Generators (TEGs) such as bismuth telluride or lead telluride are scarce, expensive, toxic, and environmentally harmful. In recent years, the thermoelectrics paradigm has changed mainly due to the introduction of low-dimensional materials able to reduce the thermal conductivity by phonon scattering. Semiconductor nanowires have demonstrated fascinating properties with application in various fields, including energy and information technologies. In particular, increasing attention has been focused on Si nanowires (NWs) for application in thermoelectric generation after recent successful implementation in miniaturized devices. Despite this interest, a proper evaluation of such nanostructures' thermal conductivity still represents a great challenge, especially when the characterization of the device-integrated nanowire is desired. Scanning Thermal Microscopy (SThM) offers an alternative for spatially-resolved, non-destructive, and flexible evaluation of individual nanostructures' thermal conductivity. However, a big challenge remains for micro and nanostructures presenting high aspect ratios, such as the here studied suspended NWs integrated into micro platforms. In those cases, the background change along the abrupt topography of the nanostructures can be of the same order of magnitude as the signal of the nano/microstructure of interest, and thus the signal extraction is often challenging to perform. In this work, we present an alternative approach to currently existing intricate techniques for precisely measuring the mechanical and thermal properties of integrated 1D NWs. The procedure consists in performing a series of z scan approaches over the studied sample using the conductance contrast mode of the SThM. In order to achieve nanometer precision while working into a vacuum environment, the used custom-made SThM was inserted into a Scanning Electron Microscope (SEM). By correlating the force-z and the probe current-z curves, the heat change produced in the contact can be accounted for and used to compute the thermal conductivity whereas deflection is used for the mechanical assessment. This approach eliminates the need for background subtraction. As a case study, the thermal conductivities of a Si NWs integrated in silicon microdevices were measured. Thermal conductivity values of 14.2 W/m·K were estimated for Si NWs. Indeed, up to our knowledge, this is the first-time reported use of a combined SEM-SThM in order to assess the thermal conductivity of a device-integrated 1D nanostructure. Finally, the range of applicability according to the sample thermal conductance and associated errors are discussed to establish the potential of the novel approach [1]. The results presented here show the remarkable utility of combined SEM-SThM for the challenging thermal characterization of integrated nanostructures and the development of multiple devices such as thermoelectric generators or photovoltaic cells.

Authors : Haydn Francis(a,b), Dr. Zachary Ruff (a,b), Dr. Zenon Toprakcioglu(a), Prof. Clare Grey (a,b), Prof. Hugo Bronstein(a,b,c)
Affiliations : a: Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK; b: The Faraday Institution, Didcot, Oxford, UK; c: The Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK

Resume : Molecular ionophores have been identified as promising candidates for the next generation of Li-ion selective sensors. Colorimetric, fluorescence and electrochemical based systems have been shown to produce sensors of greater specificity and selectivity than the current alternatives to ionophore-based systems. Integration of these kinds of sensing frameworks onto solid supports (e.g. optodes and optical fibres) has emerged as a strong avenue for passive, in-situ and real-time sensing of metal ions in a number of applications. Li-ion sensing using optical techniques is especially desirable for in-situ measurements in Li-ion batteries. In theory, these systems could be used to monitor lithium depletion and concentration gradients in battery electrolytes in-situ, which are both associated with performance loss. The current options for monitoring these processes involve techniques, which are not likely to be used for batteries in the field due to the size and cost of equipment and the need for bespoke cell designs. Solution state fluorescent molecular sensors have been used to measured Li-ion diffusion in conditions comparable to common electrolytes, but would likely result in contamination of the electrolyte and alteration of battery chemistry if applied in-situ. Immobilisation of sensing molecules will likely be a requirement for any device that can be used in-situ in Li-ion batteries and could be used to create probes that are small, low cost and easily integrated into commercial batteries. We present a new fluorescence Li+-sensing platform based on a single-step functionalisation of mesoporous silica glass with a new fluorescent dye. The sensing functions based on a fluorophore-ionophore couple between a naphthalene diimide core and an aza-crown ionophore, displaying altered absorbance properties and “turn-on” fluorescence in the presence of Li+. Functionalization of the dye with a trialkoxysilane group enabled covalent grafting to silica in a single step. This process was used to create Li+-selective optodes ca-pable of sensing over a wide concentration range (10-7 - 1 M). Fluorescence microscopy on the optodes was employed to track Li+ concentrations with spatial resolution in a commercial solvent-salt system for Li-ion batteries. This is the first example of spatial Li+ tracking using a solid-supported optical sensor and represents a key proof of concept in moving towards using fluorescence methods for in-situ measurements of Li+ concentration in Li-ion batteries.

13:00 Lunch Break    
Advanced Sensor Materials I : J. Adam
Authors : Abhishek Kumar Mishra, Kamal Kumar
Affiliations : University of Petroleum and Energy Studies (UPES)

Resume : Experimentally it has been found that copper oxide surfaces consist of mixed Cu2O and CuO moieties, and there is therefore a need to identify an appropriate value for the U parameter, which can describe adequately both CuO and Cu2O in terms of experimental properties. Recently, we determined such a U parameter, through systematic investigation of structural, magnetic, and electronic properties of both the copper oxides [1]. We have employed DFT with this Hubbard U correction to explore CO2 adsorption on different non-polar stoichiometric terminations of the (111), (110), and (001) surfaces of Cu2O [2]. CO2 hydrogenation to useful chemical products such as formic acid and methanol is of great interest and we recently found Cu2O as a suitable catalyst for CO2 conversion to formate and formic acid under mild conditions. We used DFT+U methodology to investigate CO2 hydrogenation to formic acid and fuels formation on copper oxide. Different routes have been investigated towards formic acid formation and results show that carboxyl intermediate is more favourable compared to formate intermediate on CuO(111), which is contrast to hydrogenation on Cu2O(111) surface, where formate route was found to be energetically favoured [3]. Density functional theory (DFT) based calculations were carried out on CO2 hydrogenation processes on the CuO surfaces and compared with the experimental results to suggest the potential mechanisms of formate formation and subsequent CO/CH4 conversion with the observed catalyst phases [4]. Transition metal carbides (MXenes) with formula Mn+1CnTx (n = 2 and 3) have been emerging as a new family of two-dimensional (2D) materials that have great potential in electronic applications and CO2 conversion catalysts. Herein, we systematically study the effect of the different types of structural defects on the structural stability, electronic behavi or, and electrochemical properties of ordered Mo2TiC2Tx terminated with the specific surface functional groups of fluorine, oxygen, and hydroxide. The calculated defect formation energies imply that the formation of defects is dependent on the surface terminations, where the O-terminated MXenes demand more energy than the F- and OH-terminated MXenes. We found that defect formation is more feasible in the outer molybdenum layers than in the inner titanium layer. Our results predicted that the CO2 molecule adsorbs on the defective surfaces through a spontaneous and exothermic process that is critical to its capture, while the perfect surface weakly attracts the molecule through a nonspontaneous and endothermic process. Thus, our study predicts that the electronic and electrochemical properties of Mo2TiC2Tx can be tuned by forming specific defects and these MXenes could be promising materials for CO2 adsorption and conversion [5]. Hybrid metal oxide nano- and microstructures exhibit novel properties, which make them promising candidates for a wide range of applications, including gas sensing. Calculations based on density functional theory (DFT) have been carried out to model different active surfaces of different metal doped ZnO based tetrapods [6-8]. 1. “CuO Surfaces and CO2 activation : A dispersion corrected DFT+U study”, Abhishek Kumar Mishra, Alberto Roldan, and Nora H. de Leeuw, J. Phys. Chem. C, 120 (4), 2198 (2016). 2. “Density Functional Theory Study of the Adsorption Behaviour of CO2 on Cu2O Surfaces”, Abhishek Kumar Mishra, A. Roldan and N. H. de Leeuw, J. Chem. Phys. 145, 044709-13 (2016). 3. “Mechanistic insights into the Cu(I) Oxide-catalyzed conversion of CO2 to fuels and chemicals: A DFT Approach” Abhishek Kumar Mishra, and Nora H. de Leeuw, Journal of CO2 Utilization, 15, 96-106 (2016). 4. “A combined EXAFS, XRD, DRIFTS and DFT study of nano copper-based catalysts for CO2 hydrogenation”, Kalyani Gupta, Marco Bersani, Abhishek Kumar Mishra, S.F. Rebecca Taylor, Husn-Ubayda Islam, Nathan H. Hollingsworth, Christopher Hardacre, Nora H. de Leeuw, Jawwad A. Darr, ACS Catal., 6, 5823 -5833 (2016). 5. Atomic defects in monolayer ordered double transition metals carbide (Mo2TiC2Tx) MXene and CO2 Activation”, Rasoul Khaledialidusti, Abhishek Kumar Mishra and Afrooz Barnoush , J. Mater. Chem. C,8, 4771-4779 (2020). 6. Multifunctional Materials: A Case Study of the Effects of Metal Doping on ZnO Tetrapods with Bismuth and Tin Oxides”, O. Lupan, V. Postica, A. K. Mishra, Nora H. de Leeuw, J. F. C. Carreira, J. Rodrigues, N. Ben Sedrine, M. R. Correia, T. Monteiro,V. Cretu,I. Tighineanu, D. Smazna, Y. K. Mishra, R. Adelung, Advanced Functional Materials, 27, 1604676-15 (2017). 7. “Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications”, O. Lupan, V. Postica, J. Gröttrup, A. K. Mishra, N. H. de Leeuw, J. F. C. Carreira, J. Rodrigues, N. Ben Sedrine, M. R. Correia, T. Monteiro , V. Cretu, I. Tiginyanu, D. Smazna, Y. K. Mishra , and R. Adelung, ACS-Applied Material Interface, 9 (4), 4084–4099 (2017). 8. “Pd-Functionalized ZnO:Eu Columnar Films for Room-Temperature Hydrogen Gas Sensing: A Combined Experimental and Computational Approach” Cristian Lupan, Rasoul Khaledialidusti, Abhishek Kumar Mishra, Vasile Postica, Maik-Ivo Terasa, Nicolae Magariu, Thierry Pauporté, Bruno Viana, Jonas Drewes, Alexander Vahl, Franz Faupel, and Rainer Adelung, ACS Appl. Mater. Interfaces 12, 22, 24951–24964 (2020).


Resume : In this work, a MEMS-based micro DMFC structure of 1cm2 is proposed. It was fabricated using 3D printing technology. Pt-Sn/C was identified as the novel catalyst in DMFC technology which offers good current density. Pt-Sn/C was synthesized by the microwave-assisted chemical route and the nanoparticle of the same was derived. The MEA with the electrolyzer of Nafion membrane was fabricated with the acting anode medium of Pt-Sn/C and the cathode catalyst of pure Pt. The MEA of 1 cm2 was attached with the DMFC cell and the experimentation was carried out for the methanol of different concentrations. Methanol vapour was allowed for the anodic oxidation at Pt-Sn/C where the air was pumped at the cathodic end for the reduction reaction. The produced current was amplified and the sensor’s minimal detection ability of methanol was tested and results are presented.

Authors : Sang-Joon Park, Jun-Young Jeon, Tae-Jun Ha
Affiliations : Department of Electronic Materials Engineering, Kwangwoon University, Seoul 01897, Republic of Korea

Resume : Many studies to demonstrate chemical sensors detecting ultralow concentrations (ppb-level) of nitrogen oxide (NOx) gas molecules which are one of biomarkers in respiratory inflammation have been reported for breath analysis [1]. Nanostructured metal-oxide semiconductors or low-dimensional nanomaterials have been investigated for active sensing materials owing to their superb electrical characteristics, good thermodynamic stability, and large surface-to-volume ratio [2]. However, their requirements of high operating temperatures and complicated processes can limit their potential for chemiresistive-type gas sensors [3]. Recently, ionic liquids (ILs) exhibiting excellent mechanical flexibility, outstanding thermal and chemical stability, and high ionic conductivity have been of great scientific and technological interests in ionotronic applications [4]. In this presentation, we will demonstrate polymerized ILs incorporated with 3D polymer networks which immobilize the ILs while maintaining distinctive IL properties. We will also demonstrate chemiresistive-type wearable gas sensors, which can detect NOx gas molecules down to ppb-level. Excellent operational stability under various environmental and mechanical conditions such as humidity, temperature, and physical deformation will be discussed for practical breath analysis. References: 1) W. Z. Li, M. R. Wu, C. Y. Tung, C. Y. Huang, C. S. Tan, Y. S. Huang, L. J. Chen and R. H. Horng, ACS Appl. Electron. Mater., 2, 1365-1372 (2020), 2) S. G. Chatterjee, S. Chatterjee, A. K. Ray and A. K. Chakraborty, Sensors Actuators, B Chem., 221, 1170-1181 (2015), 3) A. T. T. Do, H. T. Giang, T. T. Do, N. Q. Pham and G. T. Ho, Beilstein J. Nanotechnol., 5, 1261-1267 (2014), 4) L. Liang, X. Chen, W. Yuan, H. Chen, H. Liao and Y. Zhang, ACS Appl. Mater. Interfaces, 13, 25410-25420 (2021).

Authors : Paula González1,2, Roberto Fernandez3, María Isabel Arriortua3, Ana Catarina Lopes2
Affiliations : 1Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, 1505 Franklin Boulevard, Eugene 97403, OR, USA 2Macromolecular Chemistry Research Group (LABQUIMAC), Dept. of Physical Chemistry. Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Spain 3BCMaterials, Basque Center for Materials, Applications and Nanostructures, Bldg. Martina Casiano, UPV/EHU Science Park, Barrio Sarriena s/n, 48940 Leioa, Spain

Resume : The monitoring of different harmful gases such as volatile organic compounds (VOCs) is essential to ensure the air quality and population security. Therefore, the development of rapid, cheap and accurate sensing devices is a key to enable continuous monitoring of the air quality. On this matter, magnetoelastic sensors have become an interesting alternative to the current sensing systems because, besides exhibiting a fast response and be very cheap, they present a wireless sensing capacity. Despite their potentials there are some keys issues to be improved on then such as their mass sensitivity as well as their functionalization with active layers with high adsorption capacities and selectivity toward a specific analyte. In this context, this work explore the improve of these parameters. First, different resonators geometries are explored to improve the sensitivity of the magnetoelastic system. FEM simulations are employed to understand the behaviour of the different shapes and their expected behaviour which is further confirmed experimentally. Results show that when using a rhombic resonator instead of a rectangular one the sensitivity improve considerably. After that, the functionalization of the resonator with highly porous metal–organic frameworks (MOFs) active layers to endows it with the desired adsorption capacity and selectivity to detect VOCs is explored. After that first approaches, the performance of a rhombic magnetoelastic Metglas 2826 MB resonator functionalized with a high-toluene adsorption capacity MOF layer (i.e. UiO66-NH2) is explored for its wireless detection. Results confirm the feasibility of the Metglas/MOF system for fast and reversible toluene detection, being key the control of the active layer mass to improve its sensitivity as well as the resonator geometry. Finally, the sensor selectivity was evaluated through the analysis of the sensor response to different atmospheres (water, acetone, ethanol and toluene) observing that the sensor presents an enhanced selectivity towards toluene. Given the structural diversity and chemical tunability of MOF materials, their use as active sorbent layers in resonator systems together with the possibility to further optimize the resonator geometry to improve the sensitivity, opens the possibility for the facile and straightforward designing of future wireless sensors for any kind of environmentally hazardous substance.

15:30 Coffee Break    
Advances in Plasmonic Materials I : F. Ruffino
Authors : Isodiana Crupi1, Seweryn Morawiec2 and Manuel J. Mendes3
Affiliations : 1 Engineering Department, University of Palermo, Viale delle Scienze, Ed. 9, I-90128 Palermo, Italy 2 Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziadzka 5, 87-100 Torun, Poland 3 CENIMAT-i3N, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa and CEMOP/ UNINOVA, Caparica, Portugal

Resume : Sunlight collection in a thin film solar cell can be enhanced exploiting localized surface plasmon resonances in metallic nanoparticles (NPs). This effect is particularly pronounced in NPs made of noble metals, if the incident wavelength matches the resonance condition of the surface plasmon. However, metallic NPs themselves can have a significant undesirable light absorption. The challenge is to properly design NPs so that they maximize the scattering power and minimize the parasitic absorption. In this work, the properties of two differently self-assembled NPs, made either by the solid state de-wetting process of a thin silver film or by colloidal deposition of gold, are examined. After exploring the correlation between structural and optical properties of NPs synthetized with both techniques, we identified the fabrication conditions in which desirable NPs are obtained. The plasmonic nanostructures were then integrated into the so-called plasmonic back reflectors (PBR) to interact only with the long-wavelength light, which is not absorbed in the first pass through the cell material. PBRs formed with both approaches, a physical method based in solid-state de-wetting and a chemical method based in colloidal self-assembly, have shown similarly pronounced broadband photocurrent enhancement, relative to flat reference devices without particles, when integrated on the back of thin-film silicon cells. However, their strengths and weaknesses for practical application are quite complementary. As such, the choice between the two approach only depends on the advantages that can be explored, and disadvantages that have to be avoided, for each particular application.

Authors : Giovanni Borgh; Antonino La Magna; Giovanni Mannino; Alireza Shabani; Salvatore Patanè; Jost Adam; Rosaria A. Puglisi
Affiliations : Department of Mathematics and Computer Science, Physics and Earth Science (MIFT), University of Messina, Viale F. Stagno d’Alcontres, 31, 98166 Messina, Italy; SDU Centre for Photonics Engineering University of Southern Denmark (SDU) Campusvej 55, 5230 Odense-M, Denmark; Institute for Microelectronics and Microsystems (IMM), National Research Council (CNR), Strada Ottava 5, Zona Industriale, 95121 Catania, Italy.

Resume : Silicon nanowires (SiNWs) have represented the subject of an extensive literature since decades now. Their fascinating physical properties and their many applications in diverse field of technology - from the energy production, conversion, and storage to the sensing, photovoltaics and catalysis - make them interesting both scientifically and industrially. Some of their properties however, although intriguing, are still not deeply investigated for the difficulties related to the limits of the standard characterization techniques, and for the difficulty to interpret the experimental data. When irradiated with an electromagnetic radiation at a certain frequency the valence electrons inside the SiNW start to collectively oscillate in phase, generating the plasmonic resonances (PR). In literature discrete patterns of the PRs in SiNWs, have been mainly observed by electron energy loss spectroscopy and in structures as large as 100 nm. Thanks to the use of a cutting-edge technique based on the use of a high-resolution STEM coupled with EELS in situ, recently they have also been directly observed in SiNWs as small as 30 nm [1]. To deeply understand the plasmonic resonance in such small nanostructures and fully interpret their experimental behaviour, the work has been supported by numerical simulations on the optical dispersion data. In this talk, we will present the results of this investigation compared with new data obtained by changing SiNW sizes.

Authors : Ioannis Kochylas, Anastasios Dimitriou, Lampros Patsiouras, Maria-Athina Apostolaki, Georgia Geka, Anastasia Kanioura, Panagiota Petrou, Nikolaos Papanikolaou, Vlassis Likodimos, Spiros Gardelis
Affiliations : Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 15 784, Greece; Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, 15341 Agia Paraskevi, Athens, Greece; Institute of Nuclear & Radiological Sciences & Technology, Safety & Energy, National Center for Scientific Research “Demokritos”,15341 Agia Paraskevi, Athens, Greece

Resume : The local enhancement of the electromagnetic field induced by the excitation of surface plasmons near metallic nanostructured surfaces is utilized in many applications ranging from biosensing to cell-imaging, drug delivery and solar cells. We developed silicon nanowire (SiNWs) substrates decorated with Ag and Au nanoparticles that support particle-plasmon resonances and evaluated their performance in the detection of analytes by Photoluminescence (PL) spectroscopy, a non-invasive technique for the evaluation of material properties. In the present work, we demonstrate highly sensitive active substrates consisting of Ag decorated SiNWs fabricated by Metal Assisted Chemical Etching (MACE) on flat as well as on lithographically defined micropatterend Si substrates in a grating configuration. The Ag nanostructures were formed by applying the MACE process on Si substrates. This method included immersion of Si in an AgNO3\HF aqueous solution resulting in the formation of SiNWs decorated by silver dendrites [2]. Two types of active substrates were investigated: In the first approach, single-step MACE was performed where silver dendrites were developed inside the chemical solution through the MACE process. In the second approach a two-step MACE was performed where we first obtained SiNWs, by removing the silver dendrites formed during growth in aqueous HNO3 solution, and in a second step, silver aggregates were grown mainly on top of the SiNWs, by re-immersion in the same AgNO3/HF aqueous solution. Additional Au nanoparticles were placed on top of silver nanostructures leading to significantly higher Enhancement factors. PL was detected in two different experimental setups with a 405 nm laser beam excitation providing different spatial resolution. In the first one, the beam focused onto the samples by means of an optical fiber where the signal was obtained from a sample-area of few mm. The uniformity of the substrates was also investigated performing Micro-PL measurements where the beam was focused on the substrates by an objective lens allowing illumination of a small area of few μm and thus choosing regions with strong PL signal (hot-spots). The performance of the different substrates was evaluated with the use of aqueous solutions of Rhodamine 6G (R6G) in various concentrations. PL was more enhanced on surfaces with Ag and Au nanoparticles, compared to the base SiNWs while hot-spots with diameters of few tens of microns, observed with the Micro-PL, showed even stronger PL enhancement. Surfaces with dendritic Ag nanostructures showed somewhat better Limit of Detection (LOD). These results indicate that micropatterend, Ag-decorated MACE substrates could be used for the detection of low concentrations of fluorescent dyes. References: [1] I. Leontis, M.A.Botzakaki,S.N. Georga, A.G. Nassiopoulou , ACS Omega 3 (2018), 10898–10906. [2] I. Kochylas, S. Gardelis,V. Likodimos , K.P. Giannakopoulos ,P. Falaras and A. G. Nassiopoulou, Nanomaterials 11 (2021), 11, 1760.

Authors : Thomas Vasileiadis [1,2]; Adnane Noual [3]; Yuchen Wang [4]; Bartlomiej Graczykowski [1,2]; Bahram Djafari-Rouhani [5]; Shu Yang [4]; George Fytas [2].
Affiliations : [1] Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland. [2] Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany. [3] LPMR, Département de Physique, Faculté des Sciences, Université Mohammed Premier, Oujda, 60000, Morocco. [4] Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, 19104, PA, United States. [5] IEMN, UMR-CNRS 8520, Département de Physique, Université de Lille, Villeneuve d'Ascq, 59655, France.

Resume : Metallic nanostructures host charge oscillations, termed plasmons, which can be exploited to develop ultrasensitive chemical sensors, efficient photocatalysts, and novel types of signal-processing devices. In the so-called acoustoplasmonic devices, the various functionalities are imparted by the interaction of plasmons with acoustic excitations. In this presentation, we will discuss novel experimental and theoretical studies of the interaction of plasmons with confined acoustic vibrations in gold nanorod (NR)-polymer nanocomposites. Brillouin Light Scattering (BLS) experiments at various photon energies, combined with detailed optomechanical calculations, reveal an energy-dependent confinement of plasmons close to the tips of NR aggregates, which generates BLS hot-spots. Our work paves the way for the establishment of plasmon-enhanced BLS and promotes nanoparticle-polymer nanocomposites for acoustoplasmonic applications.

Symposium N - Poster Session : B. Sanyal, F. Ruffino, S. Sharma, J. Adam
Authors : Zhuravlev V.S., Stetsyuk T.V.
Affiliations : Frantsevich Institute for Problems of Materials Science of NAS of Ukraine

Resume : Brazing of non-metallic materials based on Al2O3, ZrO2, Si3N4, etc. with filler metal is used in instrument making, mechanical engineering, HF and IR devices, etc. Filler metal for brazing non-metallized non-metals must contain additives of capillary-active metals (Ti, Zr, Nb). The preparation of such alloy compositions and the production of foils from them is extremely difficult. In this regard, directions are being developed when the alloying of the filler metal base, which is not active towards the non-metal, is carried out by an activator during the brazing process.The activator is applied to the non-metal in the form of a paste of powders, sprayed or friction. Fusion of the solder base with the applied layer occurs during the soldering process. The purpose of this report is to consider the methods of rubbing (metallization), equipment, plating and brazing modes described in the literature, structural features of the brazing joint and properties of new brazing joints compared to traditional ones. The report also presents our results on the friction of Al2O3 with titanium and niobium. Rubbing was performed with a thin (0,1 mm) Ti or Nb disc with linear rotation speed of ~ 1 m/s. The coating thickness is 1-3 m. Wetting of coatings with Ag-Cu and Cu-Ni solders in vacuum is close to wetting with pre-activated solders. This technique significantly reduces the cost of obtaining brazing joint.

Authors : Dennis Berends, Patrick Schwager, Kai Gehrke, Martin Vehse
Affiliations : German Aerospace Center (DLR) Institute of Networked Energy Systems

Resume : Black titanium dioxide is a promising new candidate for solar water splitting due to its broad band absorption of light compared to conventional wide band gap titanium dioxide. So far, black titanium dioxide is mainly produced by hydrogenation of nanocrystalline titanium dioxide and rarely by fabricating a complete thin film. Here we show that modified magnetron sputtering can be used to deposit black titanium dioxide thin films with high photoelectrochemical water splitting activity without the need to add hydrogen to the process gas. We use bipolar reactive sputtering from two metallic titanium targets in combination with an in-situ residual gas monitoring for process feedback of the oxygen partial pressure. We change the power distribution between the two targets while keeping the oxygen partial pressure constant. As a result, one target shifts more towards the metallic regime, while the other target shifts into the oxide regime. We show that the asymmetric distribution increases the absorption of the thin films while the electrical resistivity decreases. Moreover, the band gap derived by Tauc Plot is modified towards smaller values. This process allows fine control of the optoelectronic and structural properties of the black titanium dioxide samples. Furthermore, these changes lead to an increased photoelectrochemical water splitting activity compared to samples without the modification of the power distribution. Hereby one of the samples achieves a band gap of 1.8 eV and a photocurrent density of 0.6 mA/cm^2 (at 1.5 V vs Ag/AgCl reference electrode, 560W/m^2 halogen lamp) for a power distribution of 75 % and an oxygen partial pressure of 16 ∙ 10^(-6) mbar. The results are discussed on the basis of optical, electrical and micro-structural analysis of the thin films.

Authors : Young Ki Park, Jung Jin Lee, Woosung Lee
Affiliations : Advanced Textile R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea; Department of Fiber System Engineering, Dankook University, Yongin 16890, Korea

Resume : Volatile acids such as hydrogen chloride, acetic acid, and formic acid are used in various industries including food, chemical manufacturing, and pickling. However, despite their usefulness, chemical leaks can cause great harm to the environment as well as the human body. Thus, there is a need for a device capable of detecting gas leaks simply and promptly. For this purpose, colorimetric textile sensors based on halochromic dyes that can detect chemical gas leaks with the naked eye are attracting attention. However, poor dyeability and washfastness of commercial halochromic dyes on nylon fibers are limiting their applications. Here, we introduce a UV-induced photografting method to dye nylon 6 fabrics in an eco-friendly manner and to improve the dyeability and wash fastness of halochromic dyes. In this UV photografting method, a radical-sensitive group of dye and the fiber were covalently bonded to greatly reduce dye leaching. In this study, a styrene moiety as a radical sensitive group was introduced into a rhodamine derivative with excellent pH sensitivity, and the textile sensors were fabricated via UV-induced photografting. Subsequently, the eco-friendliness of the photografting method, the gas detection performance, and washfastness of the fabricated textile sensors were investigated. Due to its low solvent and energy consumption, and the relatively short dyeing time, this UV-induced photografting method is more environmentally friendly than the conventional dip dyeing method. Furthermore, the fabricated sensors exhibited rapid and distinctive color change under acidic conditions, in addition to an outstanding washfastness. Therefore, our results indicate that textile sensors fabricated using the UV-induced photografting method are promising candidates for acid gas sensors in a wide range of applications.

Authors : Zahra Shahrbabaki, Professor Fariba Dehghani
Affiliations : School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW 2006, Australia

Resume : CO2 detection plays an important role in different fields such as air quality monitoring, medical research, marine and environmental studies, and smart food packaging. Conventionally, CO2 is detected via fluorescence, gas chromatography, and infrared spectrometry. Although these detection methods are highly selective and sensitive, the instrumentation is bulky, requires a large power supply during operation, and is relatively expensive, limiting their more widespread use in everyday applications, e.g., in-situ food monitoring. Therefore, CO2 sensors have been introduced as promising alternatives to the traditional methods for CO2 measurements. Although much progress has been made in the development of CO2 sensors, most of them suffer from some limitations such as bulkiness, high power, and energy requirement, and high cost. Thus, there is a demand for miniaturized, easy-to-implement, low-power, and inexpensive CO2 sensors. In this study, we aim to develop a cost-effective and flexible polymer-based CO2 sensor. To this end, an amine-functionalized polymer (AFP), poly(N-[3-(dimethylamino)propyl] methacrylamide) (pDMAPMAm), is selected. The AFPs-based CO2 sensors work based on the change in polymers’ electrical properties induced by the interaction between CO2 molecules and polymers’ functional group. pDMAPMAm is a CO2-responsive polymer that can be readily prepared by free radical polymerization from a commercially available and inexpensive monomer, i.e., DMAPMAm. This polymer has been used for CO2 capturing, CO2-switchable latexes, and CO2-switchable drying agents, but to the best of our knowledge, it has not been employed as a CO2-responsive polymer in the structure of sensors. A flexible chemiresistive CO2 sensor based on the pDMAPMAm is designed by 3D printing of the polymer ink along with conductive electrodes on a polyethylene terephthalate substrate enabling scalable and low-cost production. The electrical response of the fabricated sensors to CO2 is evaluated by DC resistance measurement. pDMAPMAm resistance demonstrates an interesting and unique behavior in both aqueous and solid phases. It decreases during the early stages of exposure to CO2 and then increases over time in both phases (concave upward profile); however, this behavior change is slower in the solid phase compared to the aqueous phase. The in-situ monitoring of pH suggests that there is a strong correlation between pDMAPMAm resistance, pH, and degree of protonation (DOP) of the tertiary amine groups in the presence of CO2. This two-region response of pDMAPMAm is based on a proton-hopping mechanism and a change in the number of free amines when pDMAPMAm is exposed to various levels of CO2. From these results, it can be concluded that DOP and exposure time are the key factors to be considered for designing a solid-state CO2 sensor based on pDMAPMAm. This sensor will have potential applications where the CO2 concentration increases over time like those of food packaging.

Authors : Ermes Peci, Michele Magnozzi, Lorenzo Ramò, Marzia Ferrera, Domenica Convertino, Simona Pace, Giorgio Orlandini, Apoorva Sharma, Ilya Milekhin, Georgeta Salvan, Camilla Coletti, Dietrich R.T. Zahn, Francesco Bisio, Maurizio Canepa
Affiliations : OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy; OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy and INFN, Sezione di Genova, via Dodecaneso 33, 16146 Genova, Italy; OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy; OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy; Center for Nanotechnology Innovation IIT@NEST, Piazza San Silvestro 12, 56127 Pisa, Italy and Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Center for Nanotechnology Innovation IIT@NEST, Piazza San Silvestro 12, 56127 Pisa, Italy and Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Center for Nanotechnology Innovation IIT@NEST, Piazza San Silvestro 12, 56127 Pisa; Physics Department, Technische Universität Chemnitz, Reichenhainer Straße 70, 09126 Chemnitz, Germany; Physics Department, Technische Universität Chemnitz, Reichenhainer Straße 70, 09126 Chemnitz, Germany and Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Rosenbergstraße 6, 09126 Chemnitz, Germany; Physics Department, Technische Universität Chemnitz, Reichenhainer Straße 70, 09126 Chemnitz, Germany; Center for Nanotechnology Innovation IIT@NEST, Piazza San Silvestro 12, 56127 Pisa, Italy and Graphene Labs, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Physics Department, Technische Universität Chemnitz, Reichenhainer Straße 70, 09126 Chemnitz, Germany; CNR-SPIN, corso Perrone 24, 16152 Genova, Italy; OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy.

Resume : The opto-electronic properties of two-dimensional tungsten disulfide can be manipulated via its inclusion in tailored van der Waals (vdW) multilayer heterostacks. In this work, we present a spectroscopic ellipsometry (SE) investigation of several vdW heterostacks featuring WS2 in monolayer configuration, 2H and 3R bilayer stacking, and WS2/MoS2 vertical heterostructure. Exploiting a parametric optical model, a Kramers-Kronig consistent dielectric function is extracted for each system, which allows to precisely identify the A, B and C excitons, to highlight their energetic shifts (tens-of-meV) as a function of the different stacking configuration and to rationalize them based on different dielectric environments and interlayer interaction. The stacking-dependent energy shifts of the excitonic peaks observed through SE are also confirmed by transmittance spectroscopy. An exciton tunability up to 40 meV is thus demonstrated.

Authors : Ricky Kristan M. Raguindin, Candy C. Mercado
Affiliations : Department of Mining, Metallurgical, and Materials Engineering, University of the Philippines Diliman

Resume : Rapid and more environment-friendly means of gold nanoparticle synthesis is necessary in many applications, as in ion sensing. Leaf extracts have become effective and economical reducing agents for gold nanoparticle formation, however, effects of extract combinations have not been thoroughly investigated. With the exploitation of combined extract and extract amount effects, gold nanoparticles were synthesized, then functionalized and investigated to produce selected nanoparticle systems which are capable of sensing aqueous lead (II) ions. The gold nanoparticles were mostly quasi-spherical in morphology. The biosynthesis used polyphenols and acids present in the extracts in the reduction of gold ions into gold nanoparticles, and in the nanoparticle capping and stabilization. Functionalization replaced the capping agents with organosulfur compounds. Gold nanoparticle stability in aqueous systems was verified for two weeks. The investigations concluded the practicability of the gold nanoparticles in lead (II) ion sensing with selectivity initially verified of other divalent cations.

Authors : Dr. Ulrich Schürmann, Benjamin Mockenhaupt, Dr. Sebastian Mangelsen, Prof. Dr. Lorenz Kienle, Prof. Dr. Malte Behrens
Affiliations : Ulrich Schürmann, Institute of Materials Science, Kiel University, Kaiserstraße 2, 24143 Kiel, Germany; Benjamin Mockenhaupt, Institute of Inorganic Chemistry, Kiel University, Max-Eyth-Str. 2, 24118 Kiel, Germany; Sebastian Mangelsen, Institute of Inorganic Chemistry, Kiel University, Max-Eyth-Str. 2, 24118 Kiel, Germany; Lorenz Kienle, Institute of Materials Science, Kiel University, Kaiserstraße 2, 24143 Kiel, Germany; Malte Behrens, Institute of Inorganic Chemistry, Kiel University, Max-Eyth-Str. 2, 24118 Kiel, Germany

Resume : Copper / zinc oxide / aluminum oxide catalysts can be used in the methanol synthesis. Hereby, incorporation of the trivalent aluminum into the zinc oxide improves the catalytic activity. Thereby, the structural impact and the electronic properties affects the catalysis in a positive way [1,2]. To get information about the maximum amount of aluminum on the zinc sites in ZnO the precursor Hydrozincite ((Zn1-xAlx)5(OH)6(CO3)2) with different amounts of Al (up to x = 0.1) intended to substitute Zn in the structure were synthesized. The precursors and the calcinated samples were analyzed by means of X-ray diffraction (XRD), nuclear magnetic resonance spectroscopy (NMR), X-ray photoelectron spectroscopy (XPS), as well as scanning (SEM) and transmission electron microscopy (TEM) to get information about the structure and the mechanism of Al incorporation into ZnO. XRD analysis of the precursor show reflections of the Hydrozincite and an additional Al-rich phase Zaccagnaite for Al amounts larger than x = 0.02. Above 300 °C only reflections of ZnO can be found in the diffraction pattern. The NMR analysis reveals that the Al is incorporated in the ZnO on Zn sites as well as on other sites with fourfold, fivefold and sixfold coordination. SEM as well as TEM images show larger platelets growing out of the aggregates. Energy dispersive X-ray spectroscopy (EDX) results show an increased amount of Al in these larger platelets. Diffraction pattern of the ZnO shows large (> 1µm) single crystalline regions with relative diffuse reflections indicating a disordered lattice. These results in combination with the XPS results indicate that the Al is accumulated at the surface of the flakes where the ZnO lattice is very rich in defects. [1] M. Behrens et al., Phys Chem Chem Phys 2013, 15, 1374. [2] J. Schumann et al., ACS Catalysis 2015, 5, 3260.

Authors : Soomin Lee, Gwangmook Kim, Wooyoung Lee
Affiliations : Soomin Lee, Gwangmook Kim, Wooyoung Lee; Department of Material Science and Engineering, Yonsei University, 50 Yonsei-ro, Seoul 03722, Republic of Korea Gwangmook Kim; KIURI Institute, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea

Resume : Understanding the ab-/desorption behavior of metal-hydrogen system is important to design hydrogen storages and sensing devices. Specifically, mechanical strain during hydrogenation largely affects the equilibrium partial pressure of hydrogen in metal, considering that hydrogen-induced expansion of metal is mechanically constrained by the substrate. However, it is difficult to quantitatively and separately analyze the effects of the substrate-induced strain to the metal owing to experimental artifacts such as alloying effect and hydrogenation of substrate. In this study, we utilized thin film mechanics on polydimethlysiloxane as compliant substrate to quantitatively analyze the effect of substrate constraint on the behavior of the palladium-hydrogen system in terms of initial compressive strain and strain constraint ratio from substrate. We control the initial stress on palladium film through the discrepancy of thermal expansion between palladium and PDMS during sputtering process. Strain constraint ratio from substrate to palladium film was controlled through the different widths of patterned palladium thin film. We revealed that the equilibrium partial pressure of H2 to induce phase transition strongly depends on initial thermal strain on palladium and the strain constraint ratio mainly affects the maximum solubility of hydrogen. We expected that quantitative understanding of substrate constraint of metal-hydrogen system can provide efficient strategy to destabilize hydrogen storage and to extend detectable range of hydrogen sensor.

Authors : T. Paulauskas, V. Pačebutas, J. Devenson, R. Kondrotas, A. Krotkus
Affiliations : Center for Physical Sciences and Technology, Saulėtekio al. 3, Vilnius 10257, Lithuania

Resume : We investigate the emerging dilute GaAsBi alloy as a candidate for the 1.0 eV bandgap subcell in III-V multi-junction solar cells. The bismide manifests large bandgap reduction at dilute Bi concentrations, as much as 80-90 meV/Bi%. This translates to only ~0.6% lattice-mismatch at 1.0 eV with respect to GaAs lattice. Therefore, thinner and simpler buffer layers can be devised to incorporate a thick GaAsBi absorber. Our recent study demonstrated pseudomorphic high-quality GaAsBi growth on thin InGaAs buffer layers. Here, we extend this work by synthesizing heterojunction GaAsBi-InGaAs solar cells by molecular-beam epitaxy (MBE) and investigate their performace experimentally and numerically via simulations. GaAsBi-based heterojunction solar cells with bandgaps varying 0.99 eV to 1.07 eV are synthesized on thin optimized InGaAs buffer layers. Samples with 500 nm and 800 nm thick intrinsic GaAsBi absorber layers having to nominally ~5×10^15 cm-3 acceptor concentrations as well as an n-type doped with tellurium to 1×10^17 cm-3 are analyzed. Several analytical techniques are employed, including photoluminescence measurements, external quantum efficiency and reflectance measurements, scanning transmission electron microscopy, X-ray diffraction reciprocal-space mappings, I-V measurements, as well as TCAD device modelling. Among the cells, a sample with an intrinsic 800 nm 1.05 eV bandgap GaAsBi demonstrated the best performance reaching 6.2% efficiency. This is by far the highest achieved efficiency in GaAsBi-based solar cells. Silvaco TCAD software suite was employed to determine the factors limiting GaAsBi-InGaAs photovoltaic characteristics and explore ways to improve the performance. As the numerical simulations show, the open-circuit voltage (Voc) reaches 0.41 V and is principally influenced by low carrier lifetimes, which were determined to be ~0.25 ns and ~0.1 ns for electrons and holes, respectively. This appears to be the main cause for large voltage offsets ~0.6 V in thick GaAsBi solar cells. The Voc in GaAsBi cells can be raised by an additional 0.1 V by doping the bismide to a reasonable ~5×10^16 cm-3 acceptor concentration, provided that the lifetimes do not deteriorate. The simulations indicate that by increasing GaAsBi absorber layer thickness to an optimal ~1100 nm, a current density of ~14 - 15 mA/cm2 at 1-sun AM1.5G spectrum could be achieved, thus providing current matching conditions for a 3-junction solar cell. Given superior lattice-matching conditions of a 1.0 eV GaAsBi to conventional III-V high bandgap subcell alloys, the bismide offers a new route to develop the inverted configuration solar cells for space and concentrated-sun photovoltaic applications.

Authors : Prachishree Panda, Rajat K Das
Affiliations : Senior research fellow; Assistant Professor

Resume : Recently lanthanide-based materials have gained much interest in research field due to their various light harvesting applications like optical sensors, optical imaging probes etc. Here we have developed a dual physically crosslinked lanthanide-based hydrogels using metal-ligand and hydrophobic interaction. This covalently crosslinked hydrogel matrix can be utilized for sensitization of various external stimuli like pH, temperature, metal ions and mechanical strain. By tuning the metal ions ratio, a broad emission spectrum can be obtained. The mechanical properties of the gels are greatly influenced by the metal-ligand crosslinks, which makes the system kinetically labile. By using its excellent self-recovery and fatigue resistance properties, this gel can also be used as a resistive sensor.

Authors : Jinkyo Jeong1), Hyun-Sook Lee2), Wooyoung Lee2),?
Affiliations : 1)Department of Vehicle Convergence Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea 2)Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea

Resume : Recently, interest in H2 gas sensors has increased in various applications, such as safety H2 sensors and breath H2 sensors. Therefore, the demand for H2 sensors with high and fast response, and long-term stability is increasing. Metal-oxide semiconductor (MOS)-based sensors are one of possible candidates because they exhibit high response and relatively low detection limit. However, irreversibility of MOS sensors after sensing has always been a problem in terms of long-term stability of sensors. In this study, a conductive Si (100) substrate was adopted to construct a parallel resistance circuit with H2 sensing material. The Pd-SnO2 NRs were fabricated by GLAD method on the interdigitated Cr/Pt electrodes on the Si substrate. The base resistance of the conducting channel, following the intrinsic resistance-temperature properties in air, showed remarkable stability. The highly stable and reversible base resistance-temperature relationship ascribes the Schottky junction at the interface between Pt/Cr electrode layer and p-type Si substrate. As a result, the sensor showed excellent reversibility and stability for changes between -40 ? 100 ? and sensing of 3-500 ppm H2 with fast response and recovery time at the optimal operating temperature of 80 ?. Our study demonstrated that the Pd-coated SnO2 NRs supported on conductive electrode/substrate is a possible candidate especially for use as an exquisite breath H2 analyzer.

Authors : Min-Seok Jeon 1), Jae-Hoon Lee 1), Su-Bin Heo1), Dong-Gyun Kim 2), Gi-Won Hong 2)
Affiliations : 1) Korea Testing Laboratory 2) Castman Co. Ltd.

Resume : Parts cooling, weight reduction and material substitution are increasing trends in the automotive industry, especially in electric cars. Increased power of motor and battery are demanding a more powerful cooling scheme. It would appear that electric cars using liquid cooling are the obvious choice to solve these cooling challenges. Therefore, light components having internal liquid channels are being needed to solve cooling issues in electric cars. High pressure die casting (HPDC) is the conventional casting technology for the high-volume production of light alloys; it has recently found wide application in the manufacturing of critical components, such as complex and thin geometry automotive parts. However, the major restriction of this affordable technology is the difficulty to design and realize hollow sections or components with undercuts. An innovative way to further increase the competitiveness of HPDC is to form complex undercut shaped parts through the use of new lost cores that are able endure the high pressures and temperature used in HPDC. This water-soluble salt core should have an anti-humid layer on its outer surface. Humidification of surface of salt-core usually decreases its flexural strength. Therefore salt-core must have excellent humidity resistance to ensure reliable advanced manufacturing of complex shaped aluminum diecasting with undercuts or internal cavities. This study investigates the use of innovative lost cores in the production of aluminum cooling parts by HPDC used in an electric car. Principal properties were characterized to investigate the performance of the KCl-based salt-core materials and the technology features. In addition, environmental effects of relative humidity and temperature on hydration process of layer-structured salt-core was characterized. The results were used to lead to the selection of the process parameters. These analyses demonstrate the feasibility of the production of one block hollow components by HPDC using water-soluble salt-core.

Authors : Niklas Kohlmann, Luka Hansen, Cristian Lupan, Ulrich Schürmann, Armin Reimers, Fabian Schütt, Rainer Adelung, Holger Kersten, Lorenz Kienle
Affiliations : Institute for Materials Science, Kiel University, Germany; Institute of Experimental and Applied Physics, Kiel University, Germany; Center for Nanotechnology and Nanosensors, Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, Moldova; Institute for Materials Science, Kiel University, Germany; Institute for Materials Science, Kiel University, Germany; Institute for Materials Science, Kiel University, Germany; nstitute of Experimental and Applied Physics, Kiel University, Germany; nstitute for Materials Science, Kiel University, Germany

Resume : Functional nanomaterials play a major role in the transition towards sustainable future by enabling novel catalysis, energy storage as well as generation routes. As hydrogen will be a key fuel in the future the safety of any application is a critical issue. Thus, even small leaks of highly explosive H2 need to be detected fast and reliably. H2 sensors based on nanomaterials can fulfil this task excellently while possessing small dimensions allowing for device integration. In order to tailor functional materials to their diverse applications such as the aforementioned precise control over their properties is necessary. Aside from the atomic structure itself the morphology is of great importance. Morphologies with large surface to volume ratios are well suited for catalysis or sensing applications. Here, we report on a plasma etching process facilitating the formation of ZnO nanobrushes with high surface area to volume ratios (SA:V) [1]. The ZnO nanobrushes are fabricated by an asymmetric capacitively coupled H2-C2H2 plasma treatment of self-assembled ZnO microtetrapods[2] in a self-patterned etching process. Detailed structural investigations by SEM and TEM reveal the formation of crystalline ZnO nanowire arrays atop tetrapod arms leading to an overall brush-like shape. Relative etch rates of 11 nm/min are found for 1% C2H2 admixture leading to nanowire lengths of a few 100 nm for etching times of 30-60 min. Nanobrushes show an increase in SA:V of up to 13 times compared to pristine ZnO tetrapod arms. Accordingly, single nanobrush gas sensor devices show excellent H2 sensing characteristics with a tenfold increase in gas response as well as improved response and recovery times when compared to untreated ZnO nanorod sensors. The high specific surface area of the nanobrushes make them promising candidates for applications beyond sensing such as catalysis or energy generation. Keywords: nano-on-micro, nanobrush, plasma, etching,H2 nanosensor , TEM, self-patterning & assembly References: 1. Kohlmann et al. ACS Appl. Mater. Interfaces 13, 61758–61769 (2021). 2. Mishra & Adelung. Materials Today 21, no. 6 (2018).

Authors : Nathalie Saouli [1], Marc Hayoun [1], Laurence Bodelot [2], Hichem Dammak [3]
Affiliations : [1] Laboratoire des Solides Irradiés (LSI), Institut Polytechnique de Paris, CEA/DRF/IRAMIS, CNRS, Ecole polytechnique, Route de Saclay, 91128 Palaiseau, France [2] Laboratoire de Mécanique des Solides, Institut Polytechnique de Paris, CNRS, Ecole polytechnique, Route de Saclay, 91128 Palaiseau, France [3] Laboratoire Structures Propriétés et Modélisation des Solides, CentraleSupélec, CNRS, Université Paris-Saclay, F 91190 Gif-sur-Yvette, France

Resume : Magneto-sensitive elastomers are a class of smart materials that display certain behaviours when exposed to a magnetic field. More particularly, the deformation of such elastomers in the direction of the field, called magnetostriction, has been the focus of many research studies in the last decades [1,2]. Here we present a recent numerical study using mesoscopic molecular dynamics to simulate the deformation of a non-magnetic matrix filled with randomly distributed iron microparticles. In the presence of a uniform uniaxial magnetic field, the system expands in the direction of the field, while contracting in the other two directions. Qualitatively, the obtained results are in agreement with past experimental work [3]. [1] D. Ivaneyko, V. Toshchevikov, M. Saphiannikova, G. Heinrich, Mechanical properties of magneto-sensitive elastomers: unification of the continuum mechanics and microscopic theoretical approaches, Soft Matter, 2014, 10, 2213-2225 [2] Yu. L. Raĭkher, O. V. Stolbov, Magnetodeformation effect in a ferroelastic material, Technical Physics Letter, 2000, 26, 156-158 [3] L. Bodelot, J.-P. Voropaieff, T. Pössinger, Experimental investigation of the coupled magneto-mechanical response in magnetorheological elastomers, J. Experimental Mechanics, 2018, 58, 207-221

Authors : Ulzhalgas Karatayeva, Prof. Charl F.J. Faul
Affiliations : University of Bristol, School of Chemistry, Bristol, United Kingdom

Resume : Economic growth is closely linked to greenhouse gas (GHG) emissions, such as CO2, a fossil fuel combustion product. By 2022 its atmospheric concentration has reached 418 ppm, making it the most important contributor to global GHG emissions. Therefore, research and technologies for its capture, storage and conversion are under development. Porous organic polymers (POPs) are promising materials in this area, in particular, conjugated microporous polymers (CMPs); they combine π-conjugated structures with a permanent porosity and thermal and chemical stability. The polytriphenylamine (PTPA) network is an interesting CMP owing to its tunable properties, including conductivity. These polymers are suitable for catalytic applications, resulting in materials that capture CO2 and convert it into valuable products. Moreover, the introduction of heteroatoms and functional groups into the framework can increase the ability of these materials to adsorb and convert CO2. In particular, the carboxylic acid functional group shows promise owing to high binding capabilities with CO2 molecules. Here we report a novel class of carboxylic acid functionalised PTPA CMPs, synthesised by the palladium catalysed cross-coupling reaction of amines and aryl halides. The networks have been synthesised under different conditions, such as temperature, solvent, reaction time and reactant feed ratios. Solvent choice has been directed by the Bristol-Xi’an Jiaotong (BXJ) approach to tune surface area as well as pore size distributions (PSD). High levels of control can be achieved by calculating Hansen Solubility Parameters (HSPs) of the solvents and the formed polymers. Furthermore, the HSPs of the solvents were tuned using inorganic salts. Using these methods the carboxylic acid functionalised PTPA surface area was improved from 53 m2g-1 to 364 m2g-1. In addition, CO2 uptake was increased from 4.5 wt% to 7 wt%. Electrochemical reduction of CO2, using the networks as catalytic surfaces, is under investigation. Preliminary results show that carboxylic acid functionalised PTPA networks have promising electrocatalytic activity for the conversion of CO2.

Authors : Yong YOUN, Hye-Sung KIM
Affiliations : Korea Institute of Energy Research

Resume : Proton conducting oxides have been widely researched due to their variety of applications such as fuel cells, sensors, and catalysts. In particular, proton conductors operating at low temperatures have advantages such as low cost and long lifetime in comparison with oxide-ion conductors. Acceptor-doped perovskite-type oxides like Y-doped BaZrO3 are one of the most promising candidates, showing high proton conductivity. However, there are some difficulties resulting from chemical doping like sample preparation and unexpected impurity phase formation. Recently, Ba5Er2Al2ZrO13 was introduced as a new class of proton-conducting oxides with intrinsically oxygen-deficient sites. In addition, high proton conductivity was observed without chemical doping. Nonetheless, the proton conductivity is still insufficient. Therefore, we need to understand the proton conduction mechanism to find design principles to improve the performance. Here, we elucidated the proton conduction mechanism in Ba5Er2Al2ZrO13 using the density functional theory calculations. From Gibbs free energy calculations, we identified two kinds of thermodynamically stable positions of protons, oxygen-deficient layers and perovskite layers. Also, we estimated the proton migration barriers in each layer and between layers. Our results show that the proton conduction consists of two stages: (1) the small number of protons in the perovskite layers in the early stage of hydration and (2) the majority of protons in the oxygen-deficient layers after a considerable level of hydration. We believe that these findings contribute to the development of high-performance proton conducting oxides.

Authors : Atsuhiko Ueno1, Yuki Tsuda2, Tensho Nakamura1, Tsukasa Yoshida1
Affiliations : 1: Yamagata University 2: National Institute of Advanced Industrial Science and Technology

Resume : In recent years, hybrid materials combining the functions of inorganic and organic materials have been attracting attention in the field of CO2 Reduction Reaction (CO2RR) catalysts[1]. As one method of obtaining hybrid materials, we have achieved electrochemical self-assembly (ESA) of CuSCN/organic dye hybrid thin films[2]. Furthermore, the dye loading mechanism in CuSCN/stilbazolium chromophore hybrid thin films has been found as one of the factors for controlling of ESA[3]. Currently, CuSCN/ Neutral red (NR) hybrid thin films can be converted to hybrid catalysts that show CO2RR catalytic activity by partial reduction to Cu. In this study, we focused on the compositional and structural changes of CuSCN/NR hybrid thin films and attempted to quantitatively contrast with CuSCN/ stilbazolium chromophores hybrid thin films their formation mechanism. The relationship between the NR concentration in the bath and the amount of NR precipitation in the thin films showed a steep linear slope at the low NR concentration in the bath region and a slower slope at the high NR concentration in the bath region. In the hybrid thin films were obtained at the low NR concentration in the bath region, NR was incorporated into CuSCN grains. Whereas at the high NR concentration in the bath region, NR was extracted without dissolving CuSCN by immersing the films in dimethylacetamide, confirming phase separation on the nanoscale. These results were consistent with the behavior observed for the CuSCN/ stilbazolium chromophore hybrid thin films, and changed from diffusion-limited at low NR concentrations in the bath to surface reaction limited at high NR concentrations. When CuSCN/NR hybrid thin films prepared at low NR concentration in the bath were partially reduced to Cu by constant-current electrolysis at -300 μA, exfoliation of the film occurred. On the other hand, at high NR concentration in the bath, no exfoliation occurred and the film was successfully converted to Cu. The amount of CuSCN precipitation in the hybrid thin films and the volume fraction of NR precipitation were involved from this result. Due to excessive stresses of CuSCN in the hybrid thin films during reduction under low NR concentrationin the bath, the volume fraction of CuSCN and the load on reduction were larger than that under high NR concentration in the bath. In conclusion, the dye loading mechanism in CuSCN/NR hybrid thin films was the same as that of stilbazolium chromophores, which allowed us to control the amount of NR precipitation and hybrid state in the hybrid thin films. The CO2RR catalytic performance in CuSCN/NR hybrid thin films with different hybrid states will be discussed. [1] X. Chen et al., Nat Catal., 4, 20–27 (2021) [2] Y. Tsuda et al., Microsyst Technol., 24, 715–723 (2018) [3] Y. Tsuda et al., ECS Trans., 97, 457 (2020)

Authors : Nikola Macháčová, František Karlický
Affiliations : Department of Physics, University of Ostrava, 30. dubna 22, 701 03 Ostrava, Czech Republic

Resume : Van der Waals (vdW) heterostructures of 2D materials are layered structures held together by non-covalent interactions [1]. Some heterostructures have been successfully experimentally studied, and the first devices for (nano)electronics were fabricated [2]. However, there is still no complete understanding of the theoretical background of building heterostructures with desired features. Here, we investigated the optical and electronic properties of graphene-based heterostructures using the time-dependent density functional theory (TD-DFT) method. We have previously shown that the hybrid TD-DFT method is a suitable alternative to reference many-body GW+BSE calculations of optical and excitonic properties for larger systems [3]. We created computational models of selected vdW heterostructures, identified main computational issues, and subsequently obtained its band structures and absorbance spectra of reference quality. When possible, we compared calculations to experimental results. References: [1] A.K. Geim, I.V. Grigorieva: Nature 499, 419 (2013) [2] M. Zhu, K. Wanatabe, K.S. Novoselov et al.: 2D Mater. 4, 011013 (2017) [3] T. Ketolainen, N. Machacova, F. Karlicky, J. Chem. Theory Comput., 16, 5876 (2020)

Authors : Yin-Ying Ting, Payam Kaghazchi, Piotr M. Kowalski
Affiliations : Theory and Computation of Energy Materials (IEK-13), Institute of Energy and Climate Research, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52425 Jülich, Germany Chair of Theory and Computation of Energy Materials, Faculty of Georesources and Materials Engineering, RWTH Aachen University, 52062 Aachen, Germany; Materials Synthesis and Processing (IEK-1), Institute of Energy and Climate Research, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52425 Jülich, Germany; Theory and Computation of Energy Materials (IEK-13), Institute of Energy and Climate Research, Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52425 Jülich, Germany;

Resume : Meeting the growing demand for clean energy and carbon neutrality requires efficient materials for energy storage. Cation-disordered high-entropy oxides are a class of promising high-energy-density cathode materials for Li-ion batteries [1]. Understanding the charge/discharge mechanism, redox reactions and electrochemical performance of these complex materials require a reliable description of their electronic structures. However, the complexity of ionic structures and strongly correlated character of 3d-electrons in transition metal elements (TMs) bring challenges to computational investigation of disordered TM oxide materials using first-principles. We aim to establish a methodology that will enable a realistic description of electronic and ionic structures of these materials. We will discuss the construction of thermodynamically-driven structural models of TM-oxides, produced with the Special Quasirandom Structures (SQS) method [2,3], and subsequent computation of their electronic structure with the advanced, non-standard density-functional theory method with the Hubbard U correction for strongly correlated d electrons (DFT+U). In our approach, we derive the Hubbard U parameter from first principles and apply more realistic, Wannier functions-based projectors of occupations of d orbitals of TMs [4]. The later is essential for the correct assessment of the TMs oxidation states and reliable computation of redox reactions. The computed results are validated against the experimental data, including structural and thermodynamic parameters. The development of a reliable computational methodology for mixed TM-oxides will enable an accurate, computer-aided design of durable, high-energy-density cation-disordered cathodes for Li-ion batteries. [1] Lun, Zhengyan, et al. "Design principles for high-capacity Mn-based cation-disordered rocksalt cathodes." Chem 6, 153-168 (2020). [2] Zunger, Alex, et al. "Special quasirandom structures." Physical Review Letters 65, 353 (1990). [3] Urban, Alexander, et al. "Computational design and preparation of cation‐disordered oxides for high‐energy‐density Li‐ion batteries." Advanced Energy Materials 6, 1600488 (2016). [4] Kowalski, He & Cheong. "Electrode and Electrolyte Materials from Atomistic Simulations: Properties of LixFePO4 Electrode and Zircon-Based Ionic Conductors." Front. Energ. Res 9, 653542 (2021).

Authors : Jorge Ontaneda, Keith T. Butler, Joe Briscoe
Affiliations : Jorge Ontaneda and Joe Briscoe: School of Engineering and Materials Science and Materials Research Institute, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom ; Keith T. Butler: Scientific Machine Learning Research Group, Scientific Computing Department, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot OX11 0DQ, United Kingdom

Resume : In solar energy harvesting, current photovoltaic (PV) devices (i.e., semiconductor junctions) are limited to a maximum theoretical efficiency of ~34%, referred to as the Shockley-Queisser (S-Q) limit. Semiconductors can only absorb photons with energy above the bandgap, which means that semiconductors with wide bandgaps deliver high open-circuit voltages at the cost of low currents –since they absorb less light. Conversely, systems with narrow bandgaps absorb more photons but they give low open-circuit voltages because photon energy above the bandgap is lost through thermal relaxation. Therefore, innovative technological approaches are needed to identify mechanisms that can entirely overcome this efficiency limit which might lead to drive rapid growth in renewable energy production while keeping costs low. Some ferroelectric materials can produce a photovoltaic effect without the need of a semiconductor junction, known as the bulk photovoltaic (BPV) effect which originates from the internal crystal asymmetry that gives rise to their permanent electrical polarization (P). [1–3] Most importantly, they are not subject to the S-Q limit, [4,5] and offer potential new routes to exceed current PV efficiencies. However, low photoconductivity is required for high voltage generation via the BPV effect, something that is impossible in a narrow bandgap semiconductor with efficient light harvesting. By coupling together a junction-based PV system and a BPV effect-based material in a nanocomposite thin film device, limitations of both technologies can be overcome. This idea relies on the proven ability of ferroelectrics to influence coupled materials, such as photocatalysts and organic photovoltaics. This will combine the benefits of each material, while carefully designing the system to overcome their limitations. By using the recently-developed Electronic Lattice Strain (ELS) procedure, [6] we identified the BaTiO3/hematite interface as a promising candidate for the proposed device. Screening was performed in terms of epitaxially-compatible interfaces (to minimize defects) and appropriate band alignment (to minimize charge transfer). In order to gain insights into the geometry, thermodynamics, polarization and electronic properties of the aforementioned system, Density Functional Theory (DFT) modelling is employed. To this purpose, we assume the BaTiO3 (110) surface as substrate and the hematite (100) surface is epitaxially strained to it. The epitaxial growth of hematite on the BaTiO3 substrate would result in a theoretical strain of 2.6%. Within the supercell approach, we are required to employ 5×5 surface unit cells of BaTiO3 (110) and 4×2 units of hematite (100) to reproduce the minimally strained interface. Knowledge of such an epitaxially-compatible interface will enable us to develop a model to describe and predict behavior of novel devices, validated by experiment. REFERENCES 1 K. T. Butler, J. M. Frost and A. Walsh, Energy Environ. Sci., 2015, 8, 838–848. 2 P. Lopez-Varo, L. Bertoluzzi, J. Bisquert, M. Alexe, M. Coll, J. Huang, J. A. Jimenez-Tejada, T. Kirchartz, R. Nechache, F. Rosei and Y. Yuan, Phys. Rep., 2016, 653, 1–40. 3 C. Paillard, X. Bai, I. C. Infante, M. Guennou, G. Geneste, M. Alexe, J. Kreisel and B. Dkhil, Adv. Mater., 2016, 28, 5153–5168. 4 A. Zenkevich, Y. Matveyev, K. Maksimova, R. Gaynutdinov, A. Tolstikhina and V. Fridkin, Phys. Rev. B - Condens. Matter Mater. Phys., 2014, 90, 161409. 5 J. E. Spanier, V. M. Fridkin, A. M. Rappe, A. R. Akbashev, A. Polemi, Y. Qi, Z. Gu, S. M. Young, C. J. Hawley, D. Imbrenda, G. Xiao, A. L. Bennett-Jackson and C. L. Johnson, Nat. Photonics, 2016, 10, 611–616. 6 K. T. Butler, Y. Kumagai, F. Oba and A. Walsh, J. Mater. Chem. C, 2016, 4, 1149–1158.

Authors : Shumaila Islam , Adil Alshoaibi
Affiliations : Al Bilad Bank Scholarly Chair for Food Security in Saudi Arabia, The Deanship of Scientific Research, The Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Al Ahsa, Saudi Arabia

Resume : A pH evaluation is required in numerous fields of life such as environmental monitoring, agriculture, and food science research. The chemical properties (acidity and basicity) of aqueous solutions can be determined by their pH values. Therefore, zincite-supported silica-anatase nanocomposite (ZSAC) is synthesized by the sol-gel method. Owing to the broad pH range 1–12 and fast response pH sensing characteristics, phenolphthalein is immobilized in ZSAC. FESEM analysis exhibited that both nanocomposites exhibited porous and self-assembled structures. Thermally stable ZSAC demonstrates low Ra (surface roughness) 1 nm, refractive index (n) 1.48 at 633 nm, and surface area 282 m2 /g which varied to Ra 4 nm, n around 1.5, and surface area 345 m2 /g after php immobilization. Both nanocomposites show heterogeneous chemical bonding. PZSAC revealed high pka around 11, fast color response 0.68 s in pH 12, and non-leachable behavior. Experimental findings suggested that synthesized nanocomposite has the capability for opto-chemical sensing applications.

Authors : Debolina Misra
Affiliations : Department of Physics, Indian Institute of Information Technology Design and Manufacturing Kancheepuram, Chennai, 600127, India

Resume : Electrochemical conversion of CO2 into valuable fuels has emerged as a potential solution to reduce the greenhouse gas from atmosphere and to mitigate the global warming crisis. However, activation of CO2, non-spontaneous in nature, is a major deciding factor for CO2 conversion on a catalyst surface. Recently, 2D metal-organic frameworks (MOF) possessing the same features of single atom catalysts (SACs) have gained profound interests in catalysis as they provide higher flexibility and control in terms of materials modifications than observed in materials doped with single atom catalysts. Although sizeable research in this front have been carried out by scientists on activity of metal loaded organic framework, a systematic study pertaining to the choice of metal loading is necessary for efficient application of 2D metal organic frameworks in catalysis. Employing first-principles calculations based on density functional theory (DFT), this work intends to explore the physio-chemical trend pertaining to the choice of transition metal (TM) atoms (3d, 4d, 5d) in the 2D-MOFs towards CO2 reduction reaction. As per the recent theoretical studies, nitrogen doping to graphene alters the Fermi level position, enhances the electron density and reaction properties exhibiting properties of an n-type dopant. Hence, in this work, to unravel the general activity trend in 3d, 4d and 5d TM single atoms, both pure and N-doped graphene have been used as substrates. A systematic investigation on catalytic activities of 2D organic frameworks loaded with transition metal (TM) single atoms (3d, 4d and 5d) has been carried out within the DFT framework and the reactivity order is assessed based on the CO2 adsorption energy on the catalysts in aqueous medium. The observed reactivity trend is then explained in terms of difference in charge redistribution in the material, the electron localization and valence states of TM atom species.

Authors : Ashis Ghosh, Rajat kumar Das
Affiliations : Research scholar; Assistant professor

Resume : Incorporating Fe3+- di carboxylate dynamic metal-ligand interaction along with using very small amount of chemical crosslinker, we have developed a mechanically tough and stretchable polymeric hydrogel. This polymeric hydrogel is based on poly(Acrylamide-co-maleic acid-co –butyl acrylate) copolymer that further ionically crosslinked with Fe3+ ions. This hydrogel showed high strength ( >2.5 MPa) and high stretchability (> 600% ). Along with high toughness superior flexibility, hydrogel showed good self recovery and anti fatigue properties. The strength of the hydrogel is sensitive to different stimuli like pH, metal ions, and different chemicals. By using its stimuli responsive behaviour hydrogel have been used for shape memory effect and colorimetric detection of several metal ions and organic materials. Hydrogel is highly conductive and since the conductivity is dependent on its strain, hydrogel have been used for strain sensing applications. In same way hydrogel have been used for pressure sensing applications. By attaching this hydrogel with a thermoresponsive poly(N-isopropylacrylamide) layer, a bilayer hydrogel have been formed that can detect the temperature through its actuation effect.

Authors : Lee Heedong, Yoo Namkyung, Kim Donghun, Lee Woosung
Affiliations : Advanced Textile R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea

Resume : In recent years, research on metal-organic framework(MOF) effectively adsorbing hazardous gas in the atmosphere has been actively investigated, because of its huge surface area, large pore size and surface functional groups sensitive to specific molecules. In particular, removal of aldehyde, ammonia and hydrogen sulfide gases through adsorption of MOF is of utmost interest because the gases can cause severe damage to human body. For commercialization of gas-adsorbing MOF in various fields, MOF powder needs to be combined with generally used substrates such as fabrics or polymer films. Also, suitable coating process of MOF on the fabric surface is required to maintain adsorption performance. In this study, therefore, we develop cotton fabrics containing gas-adsorbing MOF for effective adsorption of aldehyde, ammonia and hydrogen sulfide gases. To fabricate the gas-adsorbing fabrics, cotton fabrics were padded with a ligand solution and subsequently sprayed with a metal ion solution. After the process, the prepared fabrics were sealed and left at room temperature for stronger binding of MOF on the fabric surface. Adsorption test of the fabrics with formaldehyde, ammonia and hydrogen sulfide gases showed excellent adsorption performance of the developed fabrics. Owing to the coating process without use of polymer binder, the fabric exhibited comparable adsorption performance with flat and soft fabric surface. Furthermore, it was confirmed that the adsorption performance remained excellent even after washing. From the results, gas adsorption fabric is expected to be used in various places such as factories and home interiors.

Authors : Andrea Camellini, Michele Ghini, Andrea Rubino, Luca Rebecchi, Ilka Kriegel
Affiliations : Functional Nanosystems, Istituto Italiano di Tecnologia (IIT), via Morego 30, 16163, Genova, Italy

Resume : Metal oxide nanocrystals (MO NCs) are emerging as extremely versatile multi-functional nano-systems with the potential to address many of the current challenges in solar energy conversion and storage. Among all, the main challenges are related to the intermittent character of solar energy and the inevitable conversion losses that occur in current photovoltaic energy/storage systems [1]. These limitations as well as the growing demand to reduce the usage of toxic and not-Earth abundant materials [2] require completely innovative approaches. In this context, MO NCs such as Sn doped In2O3 (ITO) nanocrystals are gaining increasing attention due to their ability to accumulate multiple delocalized electrons per nanocrystal upon above-band gap light irradiation (i.e. photodoping process) [3]. In this contribution, by means of optical spectroscopy and oxidative titration tools, we provide evidence for multi-electron accumulation in ITO nanocrystal and their transfer to a widely employed electron acceptor [4] as well as their photo-charging dynamics. The unique peculiarities to store and extract multiple electrons together with their solution processability will favor the combinations of MO NCs with specifically designed hole acceptors to provide light-driven, steady-state, multiple charge accumulation into a single set of nano-materials.

Authors : Nicolò Petrini [1,2],Michele Ghini [1], Nicola Curreli [1], Ilka Kriegel [1]
Affiliations : [1]: Functional Nanosystems, Istituto Italiano di Tecnologia (IIT), via Morego 30, 16163 Genova, Italy; [2]: Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146, Genova, Italy

Resume : Doped metal oxide (MO) semiconductor nanocrystals (NCs) are being extensively studied because of their unique optical and electronic properties tunability. Specifically, the optoelectronic properties are determined by the inner carrier density profile and depletion layer forming at the surface, which can be engineered by tuning the structural composition (core-shell architectures) and the dopant concentration. Recently, depletion layer engineering has been demonstrated to be able to tailor localized surface plasmon resonance (LSPR) and charge-storage in Sn-doped Indium Oxide (ITO) NCs. [1] A suitable modeling of optical absorption spectrum can allow accessing information on the internal electronic structure without direct electrical measurements. In this work, we investigated the application of semiclassical multi-layer optical model that is able to simulate the optical response of NCs based on MO. In particular, we employed several experimental cases based on ITO NCs to validate the model, identifying the minimum set of physical parameters that allow to simulate the observed spectra. We considered both spectra evolution due to inner structural change in core-shell structure and post-synthetic modification of LSPR caused by photodoping. Moreover, we were able to model the double peak appearance and dynamics in the absorption spectra, which are related to inner electronic structure modification and charge storage. For all instances, we found that it is fundamental to take into

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Advances in Electronic, Spintronic and Photonic Materials : J. Adam
Authors : Rosaria A. Puglisi
Affiliations : Istituto per la Microelettronica e Microsistemi (IMM), Consiglio Nazionale delle Ricerche (CNR), Catania, Italy

Resume : Molecular Doping (MD) represents an efficient, low-cost alternative way to dope silicon. MD is based on the use of dopant containing molecules – typically ester molecules - dissolved in mesitylene. The solution forms a layer of molecules over the substrate to be doped through an immersion process in the liquid. After a successive annealing process, the dopant atoms are released from the molecular layer and diffuse inside Si where they are electrically active [Nanomaterials 2021, 11, 1899. https://]. Both the solute and the solvent contain carbon atoms, which during the annealing are released too, making MD not feasible for some technological applications because C can act as a charge carriers trap. Recently a new MD technique has been proposed for solution-based n-type doping, where the solution components are carbon-free. The technique is based on the use of phosphoric acid as a precursor of the dopant and water as solvent. The acid chosen is smaller than the ester molecules allowing for an improved molecules packing. The data demonstrate concentrations of about 1×1020 cm-3 carriers [Nanomaterials 2021,11, 2006.]. In this talk I will present an overview of the recent experimental and theoretical study on MD and on the C free n-type MD, showing also preliminary data on a different molecule providing p-type doping with concentrations as high as 6×1020 cm-3.

Authors : H. K. Kashyap*
Affiliations : Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India

Resume : Water-in-salt electrolytes (WiSEs) are high-concentration aqueous electrolyte with a thermodynamic voltage limit of about 3 V.1,2 A representative WiSE comprises a ~20 m aqueous solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. It has been observed that the addition of ionic liquids (ILs) improves the safety of WiSEs.3 In this talk, I shall outline the results of our molecular dynamics (MD) study4 on the structural arrangement in LiTFSI-based WiSE. I shall discuss how the addition of an IL (EmimTFSI) influences the microscopic structure of WiSE.4 Also, what is the influence of further addition of LiTFSI salt on the WiS-IL hybrid electrolyte structure? 1. Suo, L.; Borodin, O.; Gao, T.; Olguin, M.; Ho, J.; Fan, X.; Luo, C.; Wang, C.; Xu, K. Science 2015, 350, 938. 2. Tian, X.; Zhu, Q.; Xu, B. ChemSusChem 2021, 14, 2501. 3. Becker, M.; Rentsch, D.; Reber, D.; Aribia, A.; Battaglia, C.; Kühnel, R.-S. Angew. Chem., Int. Ed. 2021, 60, 14100. 4. Dhattarwal, H. S; Kashyap, H. K. J. Phys. Chem. B 2015, 126, 5291.

Authors : Riya Sadhukhan, Prof. Dipak Kumar Goswami
Affiliations : Department of Physics, IIT Kharagpur; Department of Physics, IIT Kharagpur

Resume : In biological systems, transmembrane proteins and ion channels contribute to most of the communications between cells and their environments. Ion channels either passively allow or actively control the flow of ions, typically Na+, K+, Ca2+, Cl-, and small molecules across the cell membrane. Although protons are not directly involved in neuronal action potential generation and propagation, proton (H+) transport is essential in many natural processes. One of the important examples is oxidative phosphorylation in mitochondria, in which proton gradients serve as a means to translate energy from the oxidation of glucose during the Kerb’s cycle into ATP, the biological energy currency. Other examples include the light-activated H+ pumping by archaeal bacteriorhodopsins, the activation of bioluminescence from H+ dinoflagellates, the bacterial flagellar motor activation, and the activity of antibiotic Gramicidin, etc. Artificial electronic platforms, which use electronic currents to carry charges, have an intrinsic difficulty connecting to the biological systems that rely primarily on ionic currents. We have developed an air-stable bio-protonic device to mimic the proton channel structure present in the cell membrane for studying proton transport through the ion channels. We fabricated a two-terminal device with the gelatin-SLB-gelatin structure to mimic the proton channel structure in the cell membrane. The used contacts materials are Al and Cu. Gelatin absorbs water molecules and creates protons (H+) through self-ionization. We have measured the current flow with increasing humidity conditions. The number of protons increases with the increase in relative humidity. As the number of protons increases, that will increase the current of the bio-protonic device. The I-V curves show H+ flow through the ion channels increases as we increase the relative humidity around the device.

Authors : Antonino Scandurra (1,2), Valentina Iacono (1,2), Maria Censabella (1,2), Antonino Gulino (3,4), Maria Grazia Grimaldi (1,2), Francesco Ruffino (1,2)
Affiliations : 1) Department of Physics and Astronomy ?Ettore Majorana?, University of Catania, via Santa Sofia 64, 95123 Catania, Italy. 2) Institute for Microelectronics and Microsystems of National Research Council of Italy (CNR-IMM), via Santa Sofia 64, 95123 Catania, Italy. 3) Department of Chemical Sciences, University of Catania, Viale Andrea Doria 6, 95123 Catania, Italy. 4) National Interuniversity Consortium of Materials Science and Technology, Research Unit of the University of Catania (INSTM-UdR of Catania), Viale Andrea Doria 8, 95125 Catania, Italy.

Resume : Green and sustainable production of hydrogen by water electrolysers is expected as one of the most promising ways for the industrial decarbonisation and to satisfy the ever-growing demand of renewable energy production and storage. Hydrogen evolution reaction in alkaline electrolyte is preferable as an industrial point of view, as it does not require the more expensive proton exchange membranes required in an acid environment. Unfortunately, hydrogen evolution reaction in alkaline electrolyte is still challenging, due to its slow kinetic. In this work we propose new nanoelectrode arrays for high Faradaic efficiency of the electro-sorption reaction of hydrogen in alkaline electrolyte. Platinum or palladium or bimetallic Pt80Pd20 (wt.%) nanoparticles (NPs) were fabricated by nanosecond pulsed laser ablation in aqueous environment. Nanoelectrode arrays were obtained by casting onto graphene paper the water based suspension of NPs. Moreover, this work comparatively describes the effects of 0.7 ?m thin films of perfluoro-sulfonic ionomer surrounding the NPs. The thin film of ionomer acts as inexpensive membrane between metal electro-catalyst and the electrolyte. Thin film of ionomer produces a significant modification in the material morphology, as well as in the nanoparticles dispersion and electrochemical performance. The NPs-GP systems have been characterized by field emission scanning electron microscopy, Rutherford backscattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge cycles. State of the art competitive Faradaic efficiency up to 86.6% and hydrogen storage capacity up to 6 wt.% have been obtained by the Pt80Pd20 system.

10:30 Coffee Break    
Advanced Catalytic Materials I : F. Ruffino
Authors : Clara Salvini, Michele Re Fiorentin, Francesca Risplendi, Giancarlo Cicero
Affiliations : Clara Salvini: Center for Sustainable Future Technologies, Istituto Italiano di Tecnologia, Torino 10144, Italy, Department of Applied Science and Technology, Politecnico di Torino, Torino 10129, Italy; Michele Re Fiorentin: Center for Sustainable Future Technologies, Istituto Italiano di Tecnologia, Torino 10144, Italy; Francesca Risplendi: Department of Applied Science and Technology, Politecnico di Torino, Torino 10129, Italy; Giancarlo Cicero: Department of Applied Science and Technology, Politecnico di Torino, Torino 10129, Italy.

Resume : In the last decades, the anthropogenic emission of carbon dioxide (CO2), one of the gases mainly responsible for greenhouse effects, has progressively increased to a level that has raised the worries of the international community due to its catastrophic environmental impact [1]. The scientific communities are focusing their attention on this problematic scenario, and new technologies for CO2 capture and reuse are currently at an explorative research level [2]. The electrochemical CO2 reduction is a promising strategy towards carbon recycling by CO2 dissolution in electrolytic solution, in which CO2 adsorbs and gets reduced at the cathode under the application of an external voltage [3]. However, several challenges must be overcome such as poor selectivity, considerable reaction barriers, sluggish kinetics and the high thermodynamic stability of the CO2 molecule. Tin dioxide (SnO2) is an efficient catalyst for the CO2 reduction reaction (CO2RR) to formic acid (HCOOH), since SnO2 samples typically present higher specific area and roughness. However, the comprehension of the SnO2 surface structure at working electrocatalytic conditions and the nature of catalytic active site is a current matter of debate. Operando Raman spectroscopic characterizations show that the highest selectivity towards HCOOH occurred at potentials where SnO2 should get completely reduced to metallic tin according to Pourbaix analysis [4, 5]. In this study, ab initio calculations have been performed to investigate how the selectivity and activity of SnO2 surfaces towards CO2RR changes at varying surface stoichiometry and increasing reduction degree. The employment of Density Functional Theory (DFT) combined with the theoretical electrochemistry approach [6] has been carried out with the Quantum ESPRESSO (QE) suite [7]. The free energy profiles for CO2RR to chemicals with a single carbon atom (C1), such as formic acid and carbon monoxide, has been compared with the competitive hydrogen evolution reaction (HER) and SnO2 self-reduction processes. The studied mechanisms involve two proton-electron transfers and a single intermediate step. The results reveal that the stoichiometric SnO2 surface is not intrinsically catalytically active at low applied potential and spontaneously loses oxygen species leading to tin rich metallic surfaces. The electrocatalyst becomes selective towards HCOOH product when at least a Sn bilayer is formed at the catalyst surface, while when SnO2 is completely reduced to metal the HER becomes competitive. [1] BP Statistical Review of World Energy, 2018. [2] J. Chem. Technol. Biotechnol. 2014, 89, 334–353. [3] Chem. Soc. Rev. 2013, 42, 6, 2423–2436. [4] K. Wandelt (Ed.), Encyclopedia of Interfacial Chemistry, Surface Science and Electrochemistry, Elsevier, 2018, 217-226. [5] ACS Catal. 2015, 5, 7498–7502. [6] J. Phys. Chem. B, 2004, 108 (46), 17886-17892. [7] J. Phys. Condens. Matter 2009, 21

Authors : G. Mineo1,2, M. Scuderi3, E. Bruno1,2, S. Mirabella1,2
Affiliations : 1 Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università degli Studi di Catania, via S. Sofia 64, 95123 Catania, Italy; 2 CNR-IMM (Università di Catania), via S. Sofia 64, 95123 Catania, Italy; 3 IMM-CNR, VIII strada 5, 95121 Catania, Italy;

Resume : WO3-based nanostructures have emerged as one of the most promising candidates for electrocatalytic hydrogen evolution reaction (HER) due to their low cost, electrochemical durability, and high stability in acidic environment. A powder of WO3 nanorods (400 nm long, 5 nm large) is produced by hydrothermal synthesis and thermal annealed. In depth investigation is performed involving transmission elector microscopy and electrochemical analysis with linear sweep voltammetry (LSV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The catalytic activity for hydrogen evolution reaction (HER) is investigated both for as-prepared and annealed WO3 nanorods demonstrating the peculiar HER dependence on crystalline phase, energy gap and oxygen vacancy density. The annealed nanostructures show the best performance in terms of overpotential (173 mV), Tafel slope (140 mV/dec) and turn-over frequency (TOF).

Authors : G. Di Mari (1,2), L. Bruno (1,2), G. Malandrino (3), G. Franzò (2), S. Mirabella (1,2), E. Bruno (1,2)
Affiliations : (1) Dipartimento di Fisica e Astronomia “E. Majorana”, Università degli Studi di Catania, Via S. Sofia 64, I-95123, Catania, Italy; (2) CNR-IMM, Via S. Sofia 64, I-95123, Catania, Italy. (3) Dipartimento di Scienze Chimiche, Università degli Studi di Catania, INSTM UdR Catania, Viale A. Doria 6, I-95125, Catania, Italy

Resume : With the fast depletion of fossil fuels and the increase of the environmental pollution, achieving a sustainable and non-effective energy supply has become crucial in material science field. Electrochemical transformation reactions, including water splitting, are suitable candidates to achieve such a goal, and are now one of the research focuses in renewable energy storage and conversion. Transition metal oxides (TMO) lead to an innovative direction for the development of materials for Hydrogen Evolution Reaction (HER) due to their low cost and excellent stability. Zinc oxide (ZnO), a primary TMO, represents a green choice due to its abundance and biocompatibility. Here we focus on a cost-efficient mass production of nanostars by means of Chemical Bath Deposition (CBD) in aqueous solution. Nanostars appear as 2D self-assembled bunch of crystalline ZnO nanorods (sized 1oo up to 1000 nm), with clear hexagonal symmetry on the assembly plane (building 6-point stars). These novel nanostructures are deeply characterized by X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM), Photoluminescence spectroscopy (PL) and electrochemical measurements in order to evidence their structural, morphological, optical and electrical properties. Zinc oxide nanostars annealead and as prepared, with and without a Pt nanoparticles decoration, have been evaluated as electrodes for HER in alkaline media. Battiato, S., Bruno, L., Terrasi, A. and Mirabella, S., ACS Applied Energy Materials, 2022. DOI: 10.1021/acsaem.1c03880

Authors : Arianit Gashi 1-2, Aissam Ait Lhouciane 3, Nicolas Batisse 3, Guillaume Monier 4, Roman Marsalek 2, Julien Parmentier 1 , Pierre Bonnet 3
Affiliations : 1- Institut de Science des Matériaux de Mulhouse (IS2M), Université de Strasbourg, Université de Haute-Alsace, 15 rue Jean Starcky, BP 2488, 68057 Mulhouse Cedex, France ; 2- Department of Chemistry University of Ostrava 30. Dubna 22, Ostrava, 701 03, Czech Republic ; 3 - Université Clermont Auvergne, Institut de Chimie de Clermont-Ferrand (ICCF), 24 Avenue Blaise Pascal, 63178 Aubiere, France ; 4 - Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut Pascal (IP), F-63000 Clermont-Ferrand, France

Resume : Graphitic carbon nitride (g-C3N4) has been investigated in the past years as an organic photocatalyst for potential application such as remediation (organics degradation), CO2 artificial photosynthesis and for water splitting under light irradiation (Ge et al., 2011). However, its applications are limited due to low utilization of the visible solar energy, low specific surface area and high recombination of photogenerated electron-hole pairs (Wang et al., 2015). Therefore, carbonitride-based nanocomposites with engineered heterojunction and/or doping of g-C3N4 with elements such as B, C, N, O and F have been investigated. Few studies focused on the fluorination of g-C3N4 and with limited doping using mainly hydrothermal methods with F- (via NH4F or analogues) (Wang et al., 2010). Recently, L. Sun et al have explored the F2 (diluted) gas approach to prepare fluorinated g-C3N4 (F/concentration of 7.05 at. %) with drastic structural distortion due to transformation of sp2 hybridization to sp3carbon atoms and enrichment of nitrogen defects (Sun et al., 2021). It results with the improvement of absorption in the visible range and of the photocatalytic performance. In order to extend the fluorination content and to investigate the resulting photocatalytic properties, carbonitride-base materials were fluorinated with pure F2 gas at room temperature. The pristine materials were defective carbonitrides (CN and CNO) prepared from melamine decomposition and a g-C3N4 nanocomposites embedding carbon nanodomains (CCN) derived from the melamine/carboxylic adduct route [(Gashi et al., 2022)]. The resulting highly fluorinated materials (F/C at ratio up to 0.96), after stabilization due to their explosive character, were characterized by a large panel of techniques such as X-Ray Diffraction, FTIR, XPS, diffuse reflectance spectroscopy (DRS), EPR in dark and visible mode and thermogravimetry analysis coupled with mass-spectroscopy (TG-MS). The photocatalytic properties of fluorinated materials were explored by studying the photodegradation kinetics of methyl orange using a Xe lamp. After a blue shift of the dye absorption band in the dark, probably related to an acidification of the media, a significantly higher kinetics of degradation was observed for all fluorinated materials compared to their pristine counterpart. refs: Gashi, A., Parmentier, J., Fioux, P., Marsalek, R., 2022. Tuning the C/N Ratio of C-Rich Graphitic Carbon Nitride (g-C3N4) Materials by the Melamine/Carboxylic Acid Adduct Route. Chem. – Eur. J. n/a, e202103605. Ge, L., Han, C., Liu, J., 2011. Novel visible light-induced g-C3N4/Bi2WO6 composite photocatalysts for efficient degradation of methyl orange. Appl. Catal. B Environ. 108–109, 100–107. Sun, L., Li, Y., Feng, W., 2021. Gas-Phase Fluorination of g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution. Nanomaterials 12, 37. Wang, H., Zhang, X., Xie, J., Zhang, J., Ma, P., Pan, B., Xie, Y., 2015. Structural distortion in graphitic-C 3 N 4 realizing an efficient photoreactivity. Nanoscale 7, 5152–5156. Wang Y, Di Y, Antonietti M, Li H., Chen X, Wang X, 2010. Excellent Visible-Light Photocatalysis of Fluorinated Polymeric Carbon Nitride Solid. Chem. Mater., 22, 5119–5121

Authors : Jorge Ontaneda, Ricardo Grau-Crespo, Georg Held
Affiliations : Jorge Ontaneda: School of Engineering and Materials Science and Materials Research Institute, Queen Mary University of London, Mile End Road, London E1 4NS, UK; Ricardo Grau-Crespo: Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK; Georg Held: Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0QX, UK

Resume : Most of the current knowledge in enantioselective heterogeneous catalysis refers to the hydrogenation of β-ketoester over Ni-based catalysts and the hydrogenation of α-ketoester on Pd-based systems. These reactions require a crucial step in the catalyst preparation: the adsorption of chiral modifiers onto the metal nanoparticles of the catalyst. In the case of the simplest β-ketoester, methyl acetoacetate (MAA), the hydrogenation results in a racemic mixture R- and S-methyl-3-hydroxybutyrate (MHB) when performed over an unmodified Raney Ni catalyst. The reaction, however, can be directed to a high enantiomeric excess if the Ni surface is modified with chiral α-amino acids or α-hydroxy acids. Even though the process is well-characterized in terms of macroscopic quantities, [1–4] information at molecular scale regarding the influence of chiral modifiers have on adsorption complex of MAA is missing. The understanding of this mechanism would help to achieve and optimize enantioselective behavior of Ni-based catalysts. By combining X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) with Density Functional Theory (DFT) modelling, we have been studying the adsorption complex of reactant MAA and typical chiral modifiers (e.g., alanine, aspartic acid, and tartaric acid) over Ni{111} and Ni{100} surfaces. [5–7] We have found MAA adsorbs on flat surfaces forming deprotonated enolate species with bidentate coordination, and the molecular plane of the adsorbate leans towards one side. These findings suggest that the role of modifiers in the enantioselective hydrogenation of MAA is to stabilize only one of two possible tilt directions, which would lead to the chiral product formation. REFERENCES 1 Y. Izumi, Adv. Catal., 1983, 32, 215–271. 2 M. A. Keane, Langmuir, 1994, 10, 4560–4565. 3 M. A. Keane, Langmuir, 1997, 13, 41–50. 4 T. E. Jones, A. E. Rekatas and C. J. Baddeley, J. Phys. Chem. C, 2007, 111, 5500–5505. 5 J. Ontaneda, R. E. J. Nicklin, A. Cornish, A. Roldan, R. Grau-Crespo and G. Held, J. Phys. Chem. C, 2016, 120, 27490–27499. 6 P. Tsaousis, J. Ontaneda, L. Bignardi, R. A. Bennett, R. Grau-Crespo and G. Held, J. Phys. Chem. C, 2018, 122, 6186–6194. 7 W. Quevedo, J. Ontaneda, A. Large, J. M. Seymour, R. A. Bennett, R. Grau-Crespo and G. Held, Langmuir, 2020, 36, 9399–9411.

Authors : Rafaela Maria Giappa, Apostolos Pantousas, Constantinos C. Stoumpos, George Kopidakis, Ioannis N. Remediakis
Affiliations : Department of Materials Science and Technology, University of Crete, Greece ; Department of Materials Science and Technology, University of Crete, Greece ; Department of Materials Science and Technology, University of Crete, Greece ; Department of Materials Science and Technology, University of Crete, Greece and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH) ; Department of Materials Science and Technology, University of Crete, Greece and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH)

Resume : Two urgent, interconnected problems of our times are the exhaust of conventional energy resources and the need to reduce CO2 emissions and move towards a sustainable carbon emission free economy. Environmentally-friendly reduction of CO2 to fuels might serve as a solution to both problems. The use of electrocatalysis or photocatalysis for this reaction will result in green fuel production that could rely on renewable energy sources alone. Up to now, CO2 reduction is at the forefront of catalysis science and is challenged by selectivity and stability issues in the existing catalytic materials and processes. Aiming to design optimized anode materials for electrochemical CO2 reduction to fuels, our quest on electrocatalytic CO2 reduction is twofold; we explore the catalytic properties of two classes of materials, transition metals and perovskite semiconductors, by means of first principles calculations. Our starting point is the best-known catalyst for CO oxidation towards CO2, which is gold nanoparticles. We employ Density Functional Theory (DFT) calculations and the Nudged-Elastic Band (NEB) method to locate reaction transition states and identify minimum-energy paths (MEPs) for chemical reactions on 10-atom gold nanoclusters. We discuss energetics of the reactions and provide insight into the conditions that favor one reaction over the other, thus helping improving catalyst selectivity. We compare to standard CO2 reduction catalysts such as single-crystal Cu. For the second family of materials, metal halide perovskites and their 2D structures and nanostructures have emerged in the last decade as superb semiconducting materials, mainly driven by their high output in photovoltaics. Many side applications have already branched out, with one being their applications in electrocatalytic and photocatalytic fuel cells. Due to their superior optical absorption and their ability to operate for a wide range of bandgaps depending on how one varies their chemical composition, metal halide perovskites can be tailored to the needs of each specific photoelectrocatalytic process. We mainly focus on 2D perovskites with bulky hydrophobic cations between the sheets of corner-connected octahedra. We perform DFT electronic-structure calculations for such systems and comment on their potential uses in environmentally-friendly catalytic processes. This research work was supported by the Hellenic Foundation for Research and Innovation (HFRI) under the project "MULTIGOLD" (HFRI-FM17-1303, KA 10480)

13:00 Lunch Break    
Advances in 2D and Pseudo-2D Materials : B. Sanyal
Authors : P. Melo (1), Z. Zanolli (1), F. Libbi (2), N. Marzari (2), M. Verstraete (3)
Affiliations : [1]: Utrecht University; [2]: EPFL; [3]: University of Liege

Resume : Interest in the optoelectronic properties of 2D materials has increased due to the discovery of the coupling between spin and valley degrees of freedom in transition metal dichalcogenides (TMDs), which can be manipulated experimentally using a circularly polarized laser. After excitation the newly formed carrier populations move towards the other valley until balance is reached. However, this relaxation process is not entirely understood in the literature, where the relative importance of the electron-electron and electron-phonon interactions is still a subject of debate. Using a fully ab-initio framework [1] we study the influence of the e-p interaction on MoSe2 after its excitation by a laser field. We show how phonons allow carrier relaxation and how the Kerr signal and total magnetization are affected at different temperatures, with the latter exhibiting a non-monotonic behaviour as the temperature increases [2]. By cross-correlating information from electronic transport and spectroscopy, we have shown that it is possible to recover previously inaccessible details of the valley structure[3]. An important conclusion was that long lived spin states probably reside within defects, which pushed us to consider the spectral signatures of different types of point defects in TMDs (figure). We find two main classes based on the presence of in-gap states, and estimate the experimental resolution needed to provide quantification of the defect concentration [4]. In hexagonal BN the negatively charged boron vacancy (V_B-) has been proposed as a qubit candidate for solid state quantum computing. Its photoluminescence dynamics is central to the preparation and readout of qubits, but is not well understood. Here we combine the approaches used above for electron phonon dynamics with those for defects: we use many body quantum dynamics within the Bethe Salpeter equation, and incorporate the coupling with phonons to analyse the deceptively simple photoluminescence spectrum of V_B-[5]. The localization of excitonic states around defects provides a benchmark for scanning probe characterization and sample quality control, and opens vistas for quantum computing platforms based on 2D materials. [1] P de Melo and A. Marini, Phys. Rev. B 93, 155102 (2016) [2] M Ersfeld et al. Nano Letters 19, 4083 (2019) [3] T Sohier et al. arXiv:2207.00452 (2022) [4] P de Melo et al. Adv Quant Mater 4, 2000118 (2021) [5] F Libbi et al. Physical Review Letters 128, 167401 (2022)

Authors : Anup Shrivastava, Shivani Saini, Sanjai Singh
Affiliations : Computational Nano-Materials Research Lab (CNMRL), Indian Institute of Information Technology-Allahabad,India

Resume : The rapid advancement in technologies and a surge in the global population with the swift Industrialization leads to severe challenges in fulfilling global energy demand. In the last few decades, researchers have been fiercely looking for the development of sustainable energy sources to achieve the goal of carbon neutrality and green energy generation. Among the various approaches to green energy generations, solar and thermoelectric conversions are the most lucrative. In both solar and thermoelectric means of energy generation, there is a direct conversion of sunlight and temperature gradient into useful electricity is possible without involving heavy mechanical instruments or hazardous gases, which makes it more robust and prone to environmental degradation. Despite the several advantages, solar cell and thermoelectric power generation are still suffering from the challenge of low power conversion efficiency and long-term stability. After the discovery of graphene in 2004, a new era of 2D materials are explored. Owing to their unique material properties, the family of two-dimensional materials immersed the research interest and vigorously investigated in recent years as robust and effective alternative materials for various components of solar cells, and thermoelectric power conversion applications. The electronic properties of 2D layered nanomaterials are very sensitive to structural perfection, and geometric symmetry plays a significant role in defining them. Recently, a new class of 2D families emerges called the Janus monolayers. In Janus formations, breaking mirror symmetry can lead to an agglomeration of new features. The Janus structures have been recently interested because they are expected to exhibit an ultra-low lattice thermal conductivity and an excellent visible-light photocatalyst with strong evidence of Rashba splitting. In this work, we have done an in-depth analysis of group-IV based Janus monolayers (Ge2XY, where X/Y=S/Se/Te), for their electronic, optical, and thermoelectric behaviors. The presence of tracking bands and multi-valleys in the E-k dispersion curve motivated to investigate the transport parameters with the other relevant characteristics. The key thermoelectric parameters such as power factor, Seebeck coefficient, and conductivity has calculated using the combined approach of density functional theory and semiclassical Boltzmann transport equations. Furthermore, the optical characteristics including Absorption coefficient, Dielectric-constant, refractive index, and extinction coefficients are calculated using the Kubo-Greenwood formalism. The impressive thermoelectric Figure-of-Merit and excellent optical characteristics advocate for the strong candidature of these materials for photovoltaic and thermoelectric devices, and hence a useful toolset to achieve the goal of carbon-neutrality with sustainable sources of energy.

Authors : Kaibo Zheng, Ziqi Liang
Affiliations : Department of Chemistry, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark; Department of Materials Science, Fudan University, Shanghai 200433, China

Resume : The unique sandwiched structure and favorable crystallization kinetics have endowed two-dimensional (2D) halide perovskites with excellent ambient stability and facile film formation compared to their three-dimensional counterparts. However, the heterogeneous crystallization of multiple n-value phases during solution-casting of 2D perovskite thin films, resulting in the random and disordered crystalline alignment in conjunction with numerous lattice defects, all of which ultimately impair device performance. Herein we demonstrate that the highly ordered lattice arrangements in 2D lead halide perovskites, exemplified as a paradigm phenylethylamine (PEA) spacer, can be achieved by 4,5-dicyanoimidazole (DCI) additive without any post-treatment. Electrostatic potential distribution mapping and X-ray photoelectron spectroscopy collectively confirm the Lewis acid-base interaction between -CN- units in DCI and Pb2+, which is conducive to homogeneous nucleation during perovskite crystallization. A sequence of in-situ grazing-incident wide-angle X-ray scattering and high-resolution transmission electron microscopy characterization unravel the epitaxial growth of multi-phases that gradually buffer internal lattice strain and consequently regulate lattice orientation, which markedly leads to a reduction of trap density and a prolongation of carrier lifetime. The resulting planar solar cells based on 2D PEA2MA3Pb4I13 (n = 4) deliver an outstanding efficiency of ~17.0% along with excellent operational stability.

Authors : Rafał Zbonikowski, Michalina Iwan, Jan Paczesny
Affiliations : Institute of Physical Chemistry Polish Academy of Sciences, ul. Kasprzaka 44/52 01-224 Warsaw

Resume : In recent years, the interest in nanotechnology has moved from equilibrium self-assembly toward dynamic self-assembly (DySA). Materials active in the presence of an external stimulus or requiring a constant energy supply are going to be the future of new complex nanotechnological systems. Such an approach needs the rational design of the building blocks of a nanocomposite. Our research focuses on the formulation of the interfacial (pseudo-2D) colloidal DySA systems with potential application to fabricate adjustable membranes or active and reconfigurable coatings. FexOy@SiO2 nanoparticles capped with thermo-responsive PNIPAM were synthesized and used as a building block with almost binary properties due to the two temperature regimes. We established the procedure of successful deposition of hydrophilic nanoparticles at the air/water interface (Langmuir film) and examined the behavior of the system upon temperature change, compression, and the ionic force of the subphase. The surface pressure and surface potential measurements were supported by SEM, BAM, DLS, profilometry, and theoretical calculations. We discussed the design of the nanoparticles in the context of possible interfacial phenomena. The different, controlled aggregation was observed due to certain stimuli, especially the temperature regime. The nanoparticles performed reversible self-assembly between a uniform state (high temperature) and a non-uniform state (low temperature). Short oligomer chains (ca. 5 nm) were able to control nanoparticles (65 nm or 90 nm) by “closing” and “opening” above and below the critical temperature (around 32 °C). As expected, the area occupied by a single nanoparticle on the ultra-pure water surface was decreased above 32 °C. However, the system changes its behavior significantly by increasing the concentration of KCl dissolved in the subphase. We discuss the interactions within the system to allow further development of 2D DySA designs. The research was financed by the National Science Centre within the OPUS grant according to decision number 2019/35/B/ST5/03229.

15:30 Coffee Break    
Multi-physical Materials I : P. Goddard
Authors : Søren Peder Madsen
Affiliations : Department of Mechanical and Production Engineering - Mechanics and Materials, Aarhus University, Denmark

Resume : Permanent magnets based on ferrites are a possible alternative, in several application areas, to rare-earth-based magnets. Their attractiveness lies in the large crystalline anisotropy, but the often used measure of performance, (BH)$_\textrm{max}$, is roughly 10x lower than that of high performance rare-earth magnets. There is thus a need to increase the performance of the ferrites, in order to bridge the gap to rare-earth magnets. This talk investigates strontium hexaferrite magnets using micromagnetic finite-element calculations, implemented using FEniCS in an Open Source python code. Scalable solvers enables calculations with realistic microstructure, up to the micro-meter scale, which is needed to understand and ultimately enhance the coercivity of the materials. Different microstructures are investigated and the exchange-spring mechanism is considered to enhance the (BH)$_\textrm{max}$ value.

Authors : Alireza Shabani, Dike Issu, Neda Rahmani, Jost Adam
Affiliations : 1Department of Mechanical and Electrical Engineering, University of Southern Denmark, DK-6400 Sønderborg, Denmark 2Computational Materials Group, SDU Center for Photonics Engineering, Mads Clausen Institute, University of Southern Denmark, DK-5320 Odense, Denmark; 2Computational Materials Group, SDU Center for Photonics Engineering, Mads Clausen Institute, University of Southern Denmark, DK-5320 Odense, Denmark; 1Department of Mechanical and Electrical Engineering, University of Southern Denmark, DK-6400 Sønderborg, Denmark 2Computational Materials Group, SDU Center for Photonics Engineering, Mads Clausen Institute, University of Southern Denmark, DK-5320 Odense, Denmark; 2Computational Materials Group, SDU Center for Photonics Engineering, Mads Clausen Institute, University of Southern Denmark, DK-5320 Odense, Denmark

Resume : Due to the advanced technological applications that fulfill human daily life needs, the importance of interdisciplinary research is extensively growing. In material science and engineering, employing a material possessing outstanding properties in various fields is of great interest. Among these materials, zinc oxide (ZnO) has the potential for having interesting optical, piezoelectric, and mechanical features. Despite the massive research to show the capabilities of ZnO, some of its derivatives lack investigations regarding their multi-physical properties. One of these compounds is Al-doped ZnO (AZO), well-known for its unique optical properties [1] but still unknown for mechanical features. In this work, we aim to seek the Opto-electro-mechanical properties of AZO by utilizing the ab-initio density functional theory technique. Specifically, we provide a theoretical method for calculating the elastic constant of any hexagonal crystal structure from atomic-scale simulations, including ZnO. To this end, we perform DFT energy calculations, including structural relaxation of pure and different Al atomic percentages of AZO, to find the crystal structure with minimum energy for LDA exchange-correlation functional. To calculate the elastic and mechanical characteristics, we apply a set of different strain matrices to the lattice vectors of ZnO (AZO) crystal structures. The extracted optical, electronic, and mechanical properties are compared with other experimental and theoretical works in the literature to verify the methodology used in this research. The generated optomechanical data, including optical dispersion functions and elastic constant matrices of pure and Al-doped ZnO, are suitable for larger-scale differential equation solvers such as the finite-element method for device modeling of any optomechanical system made of ZnO (AZO). In this way, we can readily predict the proposed compounds’ optomechanical functionality while avoiding existing limitations in experimental works. Keywords: DFT simulation, ZnO, Mechanical properties, Elastic constant [1] Shabani, A., Khazaei Nezhad, M., Rahmani, N., Mishra, Y.K., Sanyal, B., & Adam, J. (2021). Revisiting the optical dispersion of aluminum‐doped zinc oxide: new perspectives for plasmonics and metamaterials. Advanced Photonics Research, 2(4), [2000086].

Authors : Jamal Ahmad Khan, Jitendra Pratap Singh
Affiliations : Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India

Resume : There is a huge surge towards development of flexible thermoelectric thin films for powering wearable electronic devices. Herein, we report the fabrication of novel tilted structured silver selenide (Ag2Se) thin films by a two-step thermal evaporation method. We adopt a strategy of interface engineering at nanoscale regime to grow well oriented Ag2Se nanorod arrays. Firstly, silver nanorods were fabricated via Glancing angle deposition (GLAD) method followed by a facile selenization process to obtain Ag2Se nanocolumnar arrays. Further, by controlling the tilt angle, Ag2Se planar films were also fabricated. The thermoelectric performance of the obtained Ag2Se films was studied by varying their thickness. The tilted Ag2Se nanocolumnar arrays exhibits a high thermoelectric dimensionless figure-of-merit zT= 1.28 at room temperature. Meanwhile, a corresponding maximum power factor of ~3200 µW/m-K2 was attained at room temperature. The as-prepared Ag2Se nanorod arrays exhibits superior thermoelectric performance compared to planar Ag2Se thin films. The excellent thermoelectric properties could be attributed to the nanocolumnar design of Ag2Se that not only provides a pathway for electron transport but also enhances the phonon scattering at the interfaces, leading to reduced thermal conductivity. Besides, the elasticity of the Ag2Se nanorod arrays can be ascertained by their lower values of hardness (49.2 ± 5 MPa) and elastic modulus (1896.2 ± 20 MPa), which is several times smaller than their planar counterpart. This work opens a new path to design and optimize nanostructured thin films for next-generation flexible thermoelectric materials and devices.

Authors : M. Wencka, J. Dolin¨eka, D. Gačnika, A. Jelena, P. Ko¸elja, J. Luzara, A. Medend, P. Priputene, S. Vrtnika
Affiliations : Jo¸ef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, PL-60-179 Poznań, Poland; University of Ljubljana, Faculty of Mathematics and Physics, Jadranska 19, SI-1000 Ljubljana, Slovenia; University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna pot 113, SI-1000 Ljubljana, Slovenia; Slovak University of Technology in Bratislava, Faculty of Materials Science and Technology in Trnava, Jána Bottu 2781/25, 917 24 Trnava, Slovak Republic

Resume : In a continuous magnetization-demagnetization cycling at audio frequencies, a mechanically vibrating magnetostrictive material produces acoustic (sound) waves that can be annoying to a human ear. A zero-magnetostriction material, the opposite of the high-magnetostriction materials used for the actuators and sensors, in combination with magnetic softness could find its niche application for the production of “supersilent” (inaudible to a human ear) transformers, magnetocaloric refrigerators and other “humming” electromagnetic machinery in audio-frequency applications. Recent research of multi-component alloys composed of five or more chemical elements in near-equiatomic concentrations, termed high-entropy alloys (HEAs), has shown that ferromagnetic HEAs based on the magnetic 3d transition elements Fe, Co and Ni generally exhibit a tendency towards magnetic softness [1]. The number of magnetically soft materials that also show vanishing magnetostriction is currently small. Near-zero magnetostriction is present in permalloys with composition close to Ni80Fe20, sendust (Fe85Si10Al5) and Co-rich alloys near the glass-forming compositions M80T20 in the system T = Fe, Co, Ni and M = B, Si (an example is the amorphous a-Fe5Co70Si15B10). Vanishing small magnetostriction is also present in finmet alloys, prepared as two-phase nanocomposites of crystalline Fe–Si grains in an amorphous matrix. Here we present a study of the HEA system AlFeCoNiCux (x = 0.6 – 3.0) where the Cu-rich compositions in the range x = 2.0 – 3.0 possess a combination of good magnetic softness and vanishing magnetostriction, classifying as magnetically soft and supersilent materials for the audio-frequency AC applications. Magnetic softness and vanishing magnetostriction are both a consequence of the specific multi-phase micro- and nanostructure structure that develops in this HEA system. References [1] P. Ko¸elj, S. Vrtnik, A. Jelen, M. Krnel, D. Gačnik, G. Dra¸ić, A. Meden, M. Wencka, D. Jezer¨ek, J. Leskovec, S. Maiti, W. Steuer, J. Dolin¨ek: Discovery of a FaCoNiPdCu High-Entropy Alloy with Excellent Magnetic Softness, Adv. Eng. Mater. (2019) 1801055

Authors : Chia-Wei Huang, and Te-Hua Fang*
Affiliations : Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 80778, Taiwan

Resume : In this study, the mechanical characteristic of MoS2 on nickel substrate under nanoindentation and nanoscratch process by molecular dynamics (MD) simulation. The influences of the temperature, sliding depth, sliding speed, and indentation depth, on the deformation behavior and wear mechanism are surveyed. The results indicate that the higher sliding speed, larger sliding and indentation depth lead to a higher friction and normal force. The deformation of the MoS2 layer are affected by competing tip-to- layer and layer- to-substrate interactions.

Authors : D. Tucholski, K.-H. Heinig, H.-J. Engelmann
Affiliations : Helmholtz-Center Dresden-Rossendorf, Dresden, Germany

Resume : Si as anode material for lithium-ion batteries promises 10x the capacity of state-of-the-art graphite. However, Si anodes suffer from pulverization and electrode collapse due to large volume increase during lithiation. It has been shown that Si structures with sizes below about 200 nm remain stable [1]. Therefore, we try to understand the formation of Si nanosponge in µ-sized particles during quenching of AlSi droplets. Subsequently Al is removed from the as-produced particles by etching. Phase separation of Si and Al upon solidification of the molten AlSi alloy occurs in two stages: First nucleation and growth of primary Si grains and second formation of eutectic sponge in the Si depleted melt, with faster cooling leading to finer structures. Through modelling and simulation, the reaction pathway can be understood, allowing to optimize process parameters. For this, a model was developed, which has as initial state a fully liquid, spherical droplet with random distribution of atom species Al, Si, vacancies and oxygen impurities. A many body angular-dependent potential (ADP) has been employed which reproduces the Al-Si phase diagram quite reasonable. As the melt cools below the liquidus temperature, precipitation of primary Si takes place, followed by spinodal demixing of the melt upon reaching the eutectic. Nucleation is influenced by trace oxygen which modifies surface energies and leads to formation of sites for heteronucleation. The diffusion-reaction behavior of the species, including nucleation and/or spinodal decomposition are simulated with a 3D kinetic lattice Monte Carlo program [2] using the ADP-potential for the Al-Si system [3] with modifications added to model surface oxidation. This program enables large scale calculations by a bit-encoded lattice and lattice jumps via bit-manipulation. Our simulations qualitatively reproduce the Al-Si phase diagram, as well as composition dependent interface energies of solid Si to Al-Si melt and the nucleation behavior. The simulation results agree with the experimentally found Si nanostructures and highlight the relevance of oxygen impurities for their formation. This work is supported by the German federal ministry for economic affairs and climate protection under grant number 01221755/1. [1] Su et al., Adv. En. Mat. 4 (2014) 1300882 [2] Strobel et al., Phys. Rev. B 64 (2001) 245422 [3] Starikov et al., Comp. Mat. Sc. 184 (2020) 109891

Authors : A. Malik, H. S. Dhattarwal, H. K. Kashyap*
Affiliations : Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India

Resume : Deep eutectic solvents (DESs) have found their application as a potential class of solvents for nanotechnology, notably in developing novel carbon-based functional nanomaterials. Here, we have used molecular dynamics simulations to understand the structure of reline (choline chloride:urea in molar ratio 1:2) nanodroplets on carbon sheets with different strengths of DES–sheet interaction potentials. The simulated contact angle formed by the reline nanodroplet on the carbon surface is found to be greater than 150° at the lowest DES–sheet interaction strength, showing that the surface is supersolvophobic. The DES nanodroplet, on the other hand, wets the surface of the sheets at higher interaction potentials, generating an adlayer predominantly composed of urea molecules. When compared to chloride anions, the choline cation and urea molecules demonstrate stronger interactions with the carbon surface. The urea molecules have a larger density in the bulk of the nanodroplet at the supersolvophobic carbon surface, while the choline cation and chloride significantly contribute to the droplet's outer layers. Furthermore, urea molecules are found in the adlayer as well as the bulk of the droplets at solvophilic surfaces, whereas the reline–vapor interface is primarily composed of choline and chloride ions.

Authors : Yashpreet Kaur [1], M.Y. Swinkels [1], M. Camponovo [1], W. Kim [2], M.Lopez-Suarez [3], A. Fontcuberta i Morral [2], R. Rurali [3], I. Zardo [1]
Affiliations : [1] - Department of Physics, University of Basel, 4056 Basel, Switzerland [2] - Laboratory of Semiconductor Materials, Institute of Materials, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne, Switzerland [3] - Institute de Ciencia de Materilas de Barcelona (ICMAB-CSIC), 08193 Bellaterra, Barcelona, Spain

Resume : In this era, where nanoscale devices have made their way to industry, the problem of heat management still hinders their performances and is a limiting factor. To achieve the ultimate control over heat flow and cool down closely packed systems in current microchips, a thermal diode must be realized. A thermal diode is a device that allows heat to flow preferentially in one direction, thus, giving rectification. Efforts have been made as early as the 1930s to study heat rectification theoretically and experimentally by exploring several mechanisms including temperature dependence of thermal conductivity. Nanostructuring further helps in tuning the thermal conductivity due to phonon scattering effects, which was explored in nanowires for thermal rectification effects through molecular dynamic simulations in 2015. In this work, we have exploited the size and temperature dependence of thermal conductivity to manipulate heat flux and study thermal rectification experimentally. For this purpose, we investigate the thermal properties of nanowires with an abrupt change in diameter, also called telescopic nanowires. To perform precisely controlled thermal transport measurements on these nanowires, suspended Silicon nitride platforms with Joule heaters are used to apply thermal gradients and measure thermal conductivity. Further, to obtain a temperature profile along the axis of the nanowire, Raman thermometry is performed upon the application of a thermal gradient. Mapping the temperature of the heat channel also allows for extracting the thermal conductivity of each section of the nanowire, as well as the interface resistance. These are the first measurements to be performed on this kind of material system. So far, we have been able to measure rectification values ranging from 2 to 7% at different system temperatures with an average value of rectification increasing with an increasing temperature gradient. This is the first experimental indication of rectification in this material system. This research takes us a step closer in the direction of efficient thermal management and the development of thermal circuit elements.

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09:00 Plenary Session    
Materials for Energy Conversion II : B. Sanyal
Authors : Piotr M. Kowalski
Affiliations : Theory and Computation of Energy Materials (IEK-13), Institute of Energy and Climate Research, Forschungszentrum Juelich GmbH (Research Center Juelich), Wilhelm-Johnen-Straße, 52425 Juelich, Germany

Resume : Transition to sustainable and clean energy requires design of cost and performance effective, novel materials for energy conversion and storage. Computer-aided materials design can play a crucial role in development of energy technologies of the future. In particular, rapid increase in the supercomputers computing power allows for molecular level exploration of electrochemical phenomena with the first principles methods. Various materials features such as ionic and electronic structures, interface phenomena or electrocatalytic properties, to name but a few, can nowadays be effectively studied with the aid of density functional theory (DFT) calculations. However, the materials considered for energy transition contain elements with strongly correlated electrons (e.g. transition metals) and thus represent a computational challenge to quantum chemical methods. At IEK-13 we apply world-class high performance computing resources and state-of-the-art computational methodologies to enhance the fundamental understanding of energy materials and provide support for interpretation of the experimental data. A key to successful research in this field is a reliable and feasible computational approach. We discuss application of the parameter-free DFT+U method to various classes of energy materials [1-4]. We will demonstrate that the proper derivation of the Hubbard U parameter is crucial for the reliable computation of electrochemical phenomena. In this context we will discuss performance of the linear response method [5] for derivation of the Hubbard U parameter for d cations in different oxidation states and demonstrate the improvement in the method’s performance by selecting realistic projectors for the estimation of d orbitals occupations (e.g. Wannier-type orbitals) [1-3]. Last, but not least, we will discuss associated challenges encountered when computing mixed metal/metal-oxide systems [6]. Our key findings and methodology advancements were enabled through close cooperation with experimental partners and access to excellent data on the atomic scale properties of investigated materials [2-4]. [1] Kowalski, He & Cheong, Frontiers in Energy Research 9, 653542 (2021) [2] Murphy et al. Inorganic Chemistry 60, 2246 (2021) [3] Kvashnina et al. Chemical Communications 54, 9757 (2018) [4] Connor et al. Frontiers in Chemistry 9, 733321 (2021) [5] Cococcioni & de Gironcoli, Physical Review B 71, 035105 (2005) [6] Tesch & Kowalski, Physical Review B 105, 194153 (2022)

Authors : Sovanlal Mondal, Madhuchanda Banerjee, Suman Mandal, Ajoy Mandal, Dipak Kumar Goswami
Affiliations : School of Nano Science and Technology, IIT Kharagpur; Medinipur College, Medinipur; King Abdullah University of Science and Technology; Department of physics, IIT Kharagpur; Department of physics, IIT Kharagpur.

Resume : It is well known that microorganisms can produce fuels, such as ethanol, methane, and hydrogen, from organic matter. It is less well known that microorganisms can also convert organic matter into electricity in devices known as microbial fuel cells. However, interest in microbial fuel cells is increasing. Microbial fuel cells offer the possibility of harvesting electricity from organic waste and renewable biomass. Here we have used the Bacteria Escherichia Coli in our device to generate electrical energy. The important fact is that in our device without any applied voltage, we are getting a vast current(µA) concerning device current(nA). From Scanning Electron Microscopy(SEM), we can confirm that E. Coli has been trapped on the positively biased gold electrode due to the surface charge of E. Coli. And the novelty of this work is that it is not an Antigen-Antibody reaction as we haven’t used any antibody here. So we have also experimentally verified the Charge Transfer between E. Coli bacterial cell and electrode. So our device also can be used for water cleaning purposes.

Authors : Clara Salvini, Robert Brevik, Michele Re Fiorentin, Francesca Risplendi, Giancarlo Cicero, Hannes Jónsson
Affiliations : Clara Salvini: Center for Sustainable Future Technologies, Istituto Italiano di Tecnologia, Torino 10144, Italy, Department of Applied Science and Technology, Politecnico di Torino, Torino 10129, Italy; Robert Brevik: Science Institute and Faculty of Physical Sciences, University of Iceland, 107 Reykjavík, Iceland; Michele Re Fiorentin: Center for Sustainable Future Technologies, Istituto Italiano di Tecnologia, Torino 10144, Italy; Francesca Risplendi: Department of Applied Science and Technology, Politecnico di Torino, Torino 10129, Italy; Giancarlo Cicero: Department of Applied Science and Technology, Politecnico di Torino, Torino 10129, Italy; Hannes Jónsson: Science Institute and Faculty of Physical Sciences, University of Iceland, 107 Reykjavík, Iceland, Department of Applied Physics, Aalto University, FI-00076 Espoo, Finland.

Resume : Because of excessive anthropogenic emissions, the increasing concentration of carbon dioxide (CO2) in the atmosphere has led to an energy crisis and various disastrous environmental impacts [1]. This problematic scenario has received great attention by the scientific communities, which are committed to develop new technologies for CO2 capture and conversion into renewable fuels through clean and low-cost chemical processes [2]. Among possible strategies is the electrochemical reduction of CO2 as a step towards carbon recycling. There, CO2 is dissolved in an electrolytic solution and is reduced at the cathode under the application of an external voltage [3]. However, several challenges, such as high thermodynamic stability of the CO2 molecule, substantial reaction barriers, slow kinetics and poor selectivity, need to be overcome. The main single carbon atom products (C1) from CO2 conversion are carbon monoxide (CO) and formic acid (HCOOH). Open questions remain regarding the first step of CO2 electroreduction, which leads either to *COOH or HCOO-, which then evolve in subsequent step to CO or HCOOH, respectively. The challenge is to obtain an understanding of the structure-activity-selectivity relations in CO2 reduction at the various metal cathode surfaces. In this study, theoretical calculations aimed at gaining a better understanding of Ag, Pb and Zn low-index surface selectivity towards HCOOH and CO have been performed, analogous to the work of Van den Bossche et al. for Cu surfaces [4]. The calculations are carried out using electron density functional theory (DFT) with the Vienna Ab initio Simulation Package (VASP) [5]. The effect of the surrounding aqueous electrolyte is described by implicit solvent model in VASPsol [6, 7]. Tafel and Heyrovsky mechanisms have been considered: the reduction of CO2 occurs by transfer of an electron from the electrode and addition of adsorbed hydrogen atom or proton transfer from a H2O cluster, respectively. The activation energy barrier is found for a given applied voltage by identifying the saddle point on the corresponding energy surface representing the transition state for the reaction. While thermodynamic computational approaches can be used to estimate the free energy landscape of electrochemical processes by providing estimates of thermodynamic stabilities of CO2 reaction intermediates, it is important to address the kinetics as they can drastically affect the reaction progression. The calculations presented here show how the activation energy for the various reduction steps are lowered by the applied potential and provide insight on the different catalytic activity of the Pb, Ag and Zn electrodes. For all three electrode materials, the results show that the Tafel mechanism involves higher energy barrier than the Heyrovsky mechanism. [1] BP Statistical Review of World Energy, 2018. [2] J. Chem. Technol. Biotechnol. 2014, 89, 334–353. [3] Chem. Soc. Rev. 2013, 42, 6, 2423–2436. [4] J. Phys. Chem. C 2021, 125, 13802−13808 [5] Phys. Rev. B: Condens. Matter Mater. Phys. 1993, 47, 558− 0561 [6] J. Chem. Phys. 2014, 140, 084106. [7] J. Chem. Phys. 2019, 151, 234101.

Authors : Laurent PEDESSEAU (1), Pingping JIANG (1), Boubacar TRAORE (2), Mikael KEPENEKIAN (2), Claudine KATAN (2), George VOLONAKIS (2), and Jacky EVEN (1)
Affiliations : (1) Univ Rennes, INSA Rennes, CNRS, Institut FOTON - UMR 6082, F-35000 Rennes, France (2) Univ Rennes, ENSCR, INSA Rennes, CNRS, ISCR- UMR 6226, F-35000 Rennes, France

Resume : Over the last decade, the halide perovskites have emerged in the photovoltaic field as third generation of absorber materials for high-efficiency and low-cost solar cells. Today, the amazing progression of the power conversion efficiency is pushed back to 25.7% for single cells and to 29.8% for tandem cells of Perovskite/Si. Additionally, halide perovskites show interesting potentials for various applications such as Lasers, LEDs, Photodetectors, Photocatalysis. Actually, the toxicity of halide perovskites, the stability and upscaling of the related devices are still under debate even though low manufacturing costs, short payback time and abundant material resources for eventual industrialization are promising. Researchers are therefore still working on finding alternative materials1,2 based on lead-free perovskites and compatible with inkjet-printing based technologies to tackle simultaneously these 3 issues. Recent theoretical3 studies based on the Density Functional Theory focused on understanding and controlling the surface and interface functionalizations after the assembly with charge transport layer (CTL) which are the most critical parts of the device architectures4,5. Thus, the influence of the material surface termination on the properties of the interfaces with CTL, including intermediate work function calculations on free-standing slabs, has been thoroughly investigated. This clarifies "where and how" optimizing interfacial charge transport can be possible for instance by surface dipole tuning. This DROP-IT project6 has received funding from the European Union’s Horizon 2020 research and innovation Program under the grant agreement No 862656. The information and views set out in the abstracts and presentations are those of the authors and do not necessarily reflect the official opinion of the European Union. Neither the European Union institutions and bodies nor any person acting on their behalf may be held responsible for the use which may be made of the information contained herein. References: 1. Li, J. et al. Review on recent progress of lead-free halide perovskites in optoelectronic applications. Nano Energy 80, 105526 (2021). 2. Dong, Q. et al. Electron-hole diffusion lengths>175 μm in solution-grown CH3NH3PbI3 single crystals. Science 347, 967–970 (2015). 3. Traoré, B. et al. A Theoretical Framework for Microscopic Surface and Interface Dipoles, Work Functions, and Valence Band Alignments in 2D and 3D Halide Perovskite Heterostructures. ACS Energy Lett. 7, 349–357 (2022). 4. Shao, S. & Loi, M. A. The role of the interfaces in perovskite solar cells. Adv. Mater. Interfaces 7, 1901469 (2020). 5. Lin, R. et al. All-perovskite tandem solar cells with improved grain surface passivation. Nature (2022) doi:10.1038/s41586-021-04372-8. 6. DROPIT.

Authors : Neda Rahmani, Alireza Shabani, and Jost Adam
Affiliations : 1Department of Mechanical and Electrical Engineering, University of Southern Denmark, DK-6400 Sønderborg, Denmark 2Computational Materials Group, SDU Center for Photonics Engineering, Mads Clausen Institute, University of Southern Denmark, DK-5320 Odense, Denmark; 1Department of Mechanical and Electrical Engineering, University of Southern Denmark, DK-6400 Sønderborg, Denmark 2Computational Materials Group, SDU Center for Photonics Engineering, Mads Clausen Institute, University of Southern Denmark, DK-5320 Odense, Denmark; 2Computational Materials Group, SDU Center for Photonics Engineering, Mads Clausen Institute, University of Southern Denmark, DK-5320 Odense, Denmark

Resume : Searching for novel functional materials has attracted significant interest for the breakthrough in photovoltaics to tackle the prevalent energy crisis. Through density functional calculations, we evaluate the structural, electronic, magnetic, and optical properties of new double perovskites Sn2MnTaO6 and Sn2FeTaO6 for potential photovoltaic applications. Our structural optimizations reveal a non-centrosymmetric distorted triclinic structure for the compounds. Using total energy calculations, antiferromagnetic and ferromagnetic orderings are predicted as the magnetic ground states for Sn2MnTaO6 and Sn2FeTaO6, respectively. The empty d orbitals of Ta5+-3d0 and partially filled d orbitals of Mn/Fe are the origins of ferroelectricity and magnetism in these double perovskites resulting in the potential multiferroicity. The studied double perovskites have semiconducting nature and possess narrow band gaps of approximately 1.00 eV. The absorption coefficient (α) calculations showed that the value of α in the visible region is in the order of 10^5 cm-1. The structural stability, suitable band gap, and high absorption coefficient values of proposed compounds suggest they could be good candidates for photovoltaic applications. Keywords: Density functional calculations, Double perovskites, Multiferroicity, Photovoltaic applications

15:30 Coffee Break    
Advanced Sensor Materials II : J.adam
Authors : Anurag Srivastava
Affiliations : Advanced Materials Research Group, Computational Nanoscience and Technology Lab, ABV-Indian Institute of Information Technology and Management, Gwalior (M.P.) 474010

Resume : Detection of minor gas leaks in a hazardous work environment has been a challenging research problem for many decades as it involves health, safety and environmental risks. The past decade has shown enormous research contribution in terms of publication to achieve high quality sensor. A report of the World Health Organisation has revealed Gwalior is the most polluted city in India in terms of air pollution along with other 12 cities of India. The report also suggests that the Indian population living outside Kashmir and the Himalayan belt are exposed to air pollution beyond the WHO safe limits. Meanwhile, Delhi, touted as the most polluted city in the world, doesn’t feature in the list of cities with highest air pollution levels. Also, no other metro city features in the notorious list. Both experimentalists as well as theoreticians have attempted their level best to design and miniaturize sensor materials. Some of them got well recognition but still the goal to achieve quality sensor is far apart. Conventional sensors based on semiconducting metal oxide thin films, organic polymeric materials, silicon and carbon black-polymer composites have been preceded by nanostructure sensor for past decade. In this race, carbon nanostructures have been evolved as prominent candidate due to its extraordinary chemical and physical properties. 2D-nanostructures served fascinating research prospects for scientific community in past few decades. Starting with carbon nanotube (CNT) and graphene different new 1D and 2D nanostructures have been introduced with novel chemical and physical characteristic. These nanostructures are expected as quality sensor materials and are essential for miniaturizing electronic devices. The present talk will include our group’s recent computational work on 2D nanostructures for their sensor application for Air and water pollution, using density functional theory approach. Analysis has been made in terms of electronic and transport properties.

Authors : Martin Vrazel1, Marion Baillieul1, Kada Boukerma3, Remi Courson3, Patrick Loulergue2, Anthony Szymczyk2, Abdelali Hammouti4, Loic Bodiou4, Joël Charrier4, Tomas Halenkovic1, Marek Bouska1, Petr Nemec1, Virginie Nazabal2,1
Affiliations : 1Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 53210 Pardubice, Czech Republic; 2Univ Rennes 1, CNRS, ISCR - UMR6226, F-35000 Rennes, France; 3IFREMER, Laboratoire Détection, Capteurs et Mesures, 29280 Plouzané, France; 4Univ Rennes 1, CNRS, Institut Foton - UMR 6082, F-22305 Lannion, France

Resume : Due to increasing levels of pollution in water, the need for rapid and accurate detection of life-threatening substances is becoming urgent. This work dealt with aromatic hydrocarbons due to their highly damaging carcinogenic and genotoxic properties. While a number of chemical sensors are commercially available for field measurements, they still have shortcomings due to cost, multiple detection failures, actual portability, and/or reliability. Creating a sensor that would improve on these characteristics is the main objective of this paper. Various water solutions containing pollutants were prepared, with concentrations ranging from 50 ppb to 100 ppm. The samples were measured in first approach using attenuated total reflectance, allowing a direct flow measurement of aromatic hydrocarbons in water. Two polymers were tested as possible membranes, responsible for extracting molecules from water – polyisobutylene and polyhydroxybutyrate-co-hydroxyvalerate from a family of polyhydroxyalkanoates (PHAs). The former was chosen for its hydrophobicity, easy preparation and compatibility with chalcogenide thin films and the latter for its hydrophobicity and biodegrability. Both polymer layers were prepared by spin-coating and knife-coating in different thicknesses and then tested for fabrication reproducibility, analysis time, limit of detection, long-term cycle repeatability and regeneration. For polyisobutylene, the method for reproducible fabrication was relatively quickly established. The polymer was dissolved in mixture of xylenes, followed by deposition via spin-coating. The thickness of 5 µm was chosen as a compromise between the ability to extract water and the time required to reach saturation of the membrane. The peak areas as a function of concentration showed mostly a linear increase, with a step between 30 and 50 ppm. The polymer proved its ability to measure samples repeatedly after regenerating via water cycle, reaching the same values of peak areas as on the first measurement. In addition, the detection limit was reduced to 150 ppb, which promises good results in this detection range. The next step is the transposition of pollutants detection on chalcogenide waveguide with an integrated microfluidic system. The fabrication of the microfluidic cell on the polyisobutylene coating of the chalcogenide planar waveguide has been successfully performed. PHAs films in the range of 5-10 µm was for the first time prepared via spin-coating. As the preferred solvent is chloroform, with a high evaporation rate, the obtained membrane contains air bubbles, causing an imperfect contact between the polymer and the ZnSe prism or chalcogenide waveguide surface, negatively affecting the hydrocarbon extraction capacity from water. To conclude, the polyisobutylene proved to be an appropriate material for detecting aromatic hydrocarbons in water, which is compatible with chalcogenide planar waveguide. It showed low limit of detection along with capability to regenerate and possibility to integrate microfluidic cell on its surface. While PHAs seem to be a good choice as hydrophobic membranes since they are already used for filtration and have the great advantage of being biodegradable, the problem still lies in the optimization of their deposition in 5-10 µm layers and needs further improvements.

Authors : K Govardhan* & S Muthuraja
Affiliations : K Govardhan*, Department of Micro and NanoElectronics, School of Electronics Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu, India S Muthuraja Department of Sensor and Biomedical Technology, School of Electronics Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu, India

Resume : Sensing gases find a vital role in applications and industries varying from food to production, environmental to space, and medical to material synthesis. Gas sensing chambers are very vital when developing gas sensors and studying their sensing characteristics including sensitivity, selectivity, temperature dependence studies, accuracy, repeatability, responsivity, time of response etc. To accurately characterize the behaviour of the gas sensor, it is vital to analyse the behaviour of the gas sensing chamber. Most often, the design and behavioural or operating characteristics of the sensing chamber are ignored or taken for granted by the researchers. It’s imperative to design an optimised, efficient gas sensing chamber with stable and reliable operating characteristics, which this paper aims at. A portable gas sensing chamber with a low sample requirement, optimised flow characteristics over the sensing layer to enhance the surface reaction and hence the sensitivity of the gas sensor was designed using COMSOL Multiphysics software. The chamber was designed with three inlet ports to allow three different gases to be passed into the chamber for sensing. The gas flow through these inlet ports can be individually controlled to change the mixing ratio of the gases. These gases would be mixed by passing them through baffles placed at an optimised angle in the flow path creating localised vertices and hence mixing of gases. This helps in determining the gas selectivity response of the sensor. A turbulent to laminar transition zone follows the baffles to allow the mixed gas flow to transform into a laminar flow since gas sensors have higher sensitivity toward laminar gas flow over the surface than compared to turbulent flows. The optimal placement of the substrate is very critical to achieving effective laminar flow over the substrate. The sensor mounting platform was angled at 11 degrees facing the gas flow to facilitate smooth flow over the gas sensor surface and avert the formation of a boundary layer at the sensor leading edge. The sensor mounting platform is placed on an integrated heater with a Nichrome heater coil inside a stainless-steel sheath. The heater provides a quick and localised heating zone directly below the sensor. This reduces the error in the set temperature and actual temperature at the substrate. Moreover, this also facilitates a preheating zone around the sensor heating up the gas as they flow towards the sensor. The gas inlet ports, mixing baffles, the flow chamber, sensing zone and the exhaust port are aligned along the horizontal axis to prevent the formation of turbulences or flow bottlenecks in the gas sensing chamber. The paper focuses on the complete modelling of the portable gas sensing chamber, fluid dynamic studies of the gas flow inside the chamber, optimal placement of substrate, and optimal angling of the substrate facing the gas flow.

Authors : Egit Musaev,Matteo Soprani,Emilio Sardini,Costantino de Angelis,Edoardo Cantu,Mauro Serpelloni,Camilla Baratto
Affiliations : CNR-INO, PRISM Lab, Via Branze 45, 25123 Brescia, Italy; Department of Information Engineering, University of Brescia, 25133 Brescia, Italy

Resume : Tons of unexpired food are thrown away by the supermarkets every year. According to the FUSIONS report (2016), wholesale and retail food waste takes up 5% of the overall amount of waste in the European Union (EU), which corresponds to 4.6 billion tons per year. From which 4.74% is an avoidable amount of meat food waste. One of the key causes of such waste is the problem associated with the expiration dates shown on the packaging, which were presented as a crucial safety measure to prevent the consumption by customers of products that might be unsafe. Labels on food products do not reflect the different storage conditions of the product when it is transported to the store and, eventually, to the customer's residence. The general idea is to install a cellulose-based gas sensor in the food package, which will trace food quality during spoilage. Microbiological tests were employed for benchmarking. The sensor itself is made by the pure cellulose substrate with interdigitated contacts that changes its electrical parameters when it is exposed to a humid environment like in a food packaging/container. As a result, activated by water content, cellulose fibres act as the sensor for water-soluble gases released during the degradation of protein foods. We designed a setup that harvested the data from an array of six cellulose-based gas sensors simultaneously. These six sensors coupled with humidity/temperature sensors were placed in two sealed containers kept in the climatic chamber at 25°C: one container included a fresh sample of codfish’s fillet, and another test container was filled with distilled water. The resistance signals and ambient parameters were plotted on a read-out unit like a PC. After 3-4 hours from launching the experiment, sensors in both boxes reached 100% humidification. Deterioration of the fish fillets at 25°C indicated by the cellulose sensor was in line with the one obtained by the microbiological test. The control test with pure water showed that after 4 hours the sensors’ resistance reached a steady-state, while the sensors’ resistance in the container with fish fillets continued to decrease. After stabilization, the relative difference in the resistance of the sensors in the two containers was 40 %. Therefore, the designed data acquisition system can trace food spoilage.

Authors : Adil Alshoaibi , Shumaila Islam
Affiliations : Al Bilad Bank Scholarly Chair for Food Security in Saudi Arabia, The Deanship of Scientific Research, The Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Al Ahsa, Saudi Arabia

Resume : Owing to fiber-optic pH sensing, phenolphthalein immobilized SiO2 nanoparticles (P-SNPs) and phenolphthalein immobilized SiO2–TiO2 nanoparticles (P-STNPs) are synthesized by low-temperature sol-gel route. The P-SNPs revealed hierarchical structure, surface roughness (Ra) 7 nm, surface area ~442 m2 /g, n (refractive index) 1.37 at 550 nm which is significant for pH sensing. The P-STNPs exhibited granular structure, low Ra 3 nm, surface area ~219 m2 /g, n around 1.52 at 550 nm. Both matrices are thermally stable around 250 ◦C. The P-SNPs and PSTNPs sensitivity is calculated ~22 counts/pH and 19 counts/pH with the determination coefficient (R2 ) ~ 0.99. The pka value of P-SNPs is measured ~9.5 and time response 0.11s within pH 12 without leaching which is higher than P-STNPs (9.1) and 3.9 s with leaching. Experimental findings suggested P-SNPs have the potential for practical usage in intense basic media.

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Materials for Energy Conversion III : B. Sanyal
Authors : Mariachiara PASTORE
Affiliations : Laboratoire de Physique et Chimie Théoriques (LPCT), CNRS & Université de Lorraine, Boulevard des Aiguillettes, 54506 Nancy (France)

Resume : In the context of solar energy exploitation, dye- sensitized solar cells (DSCs) and dye-sensitized photoelectrosynthetic cells (DSPECs) offer the promise of cost effective sunlight conversion and storage, respectively. Dye-functionalization of bot n- and p-type semiconductors (like TiO2 and NiO) can be either exploited to build active DS photoelectrodes or tandem DSC and DSPECs devices. Computational modelling has played a prominent role in the development of the DSC technology. Here I will discuss the recent advances concerning first principles modeling of materials, interfaces and processes of n- and p-type photoelectrodes. On the photoanode side, we will discuss the recent advances toward the development of more efficient Iron-based DSCs, addressing both the dye design and the electrolyte optimization. On the photocathode side, particular emphasis will be put on the discussion of the electronic and structural properties of the complex NiO/solvent/dye/interface, whose characterization is still poor when compared to the level of understanding reached for TiO2 sensitized photoanodes, from both the experimental and computational point of view We will discuss the problem of accurately predict the energy level alignment across the dye/semiconductor interface by state of the art DFT and large scale GW calculations and the challenging definition of a proper structural model needed to reliably capture the interface complexity.

Authors : Katarzyna Grochowska
Affiliations : Laboratory of Functional Materials, Centre of Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences Fiszera 14 st., 80-231 Gdańsk, Poland

Resume : Nanostructures that can be used in environmental applications, especially related to renewable energy, its conversion and storage, are at the heart of nowadays research world. As most of the works are focused on the solar energy, the possibility of manipulation the passage of light through material is essential. One of the nanostructures that allow to control light guiding are photonic crystals – due to their periodical architecture. Herein, the closed nanopillars from titania nanotube arrays modified by pulsed-laser treatment are proposed as an exemplary electrode material. Titanium oxide nanotubes (NTs) can be grown via electrochemical process carried out in two-electrode arrangement where Ti substrate acts as an anode. Such a fabrication approach ensures growth of highly ordered architecture of titanium oxide NTs already onto the conductive substrate. After calcination at 450 deg. C oxide NTs are treated over any area and shape by laser beam precisely guided owing to the usage of motorized X-Y stage. For the optimized geometry of nanotubes and laser working parameters, the side selective plugging of nanocylinders can be reached offering unique structure. In the exception of closing of NTs tops, the remaining architecture of oxide support remains intact providing the straight percolation path. This is supported both by the scanning and transmission electron microscopies inspection. The appearance of the interference fringes in the reflectance spectra of the proposed material can be an indicator of the photonic crystal behavior [1]. Additional modification of the titania based platform with Fe, Co, Ni and Cu magnetron deposited layers prior to the laser treatment leads to the further altering of optical properties as the metal species are accumulated at the top part of capped NTs [2]. The electrochemical investigations of prepared materials show that the intense light-matter interaction results in improved photocatalytic activity toward oxygen evolution reaction. Moreover, precise laser sealing can be also used for the selective closing of nanotubes filled in with the nanoparticles, e.g. luminescent ones and then used for unique labelling. Thus, proposed electrodes could be further utilized in photonics or electrochemical applications. Furthermore, easy upscaling can be reached since both anodization and laser treatment are well-mastered processes onto the technological scale. This work received financial support from the Polish National Science Centre: grants no 2017/26/E/ST5/00416, 2020/02/Y/ST8/00030 and 2021/41/B/ST8/01849. [1] J. Wawrzyniak, J. Karczewski, P. Kupracz, K. Grochowska, E. Coy, A. mazikowski, J. Ryl, K. Siuzdak, Scientific Reports 10 (2020) 20235 [2] J. Wawrzyniak, J. Karczewski, E. Coy, J. Ryl, K. Grochowska, K. Siuzdak, Nanotechnology 33 (2022) 205401

Authors : Dominik Moritz (a), Mohammad Amin Zare Pour (b), Azahel Ruiz (c), David Ostheimer (b), Agnieszka Paszuk (b), Bernhard Kaiser (a), Wolf Gero Schmidt (c), Thomas Hannappel (b), Jan Philipp Hofmann (a), Wolfram Jaegermann (a)
Affiliations : (a)Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, 64287 Darmstadt, Germany; (b)Grundlagen von Energiematerialien, Technical University of Ilmenau, 98693 Ilmenau, Germany; (c)Theoretische Physik, Univ. Paderborn, 33095 Paderborn, Germany

Resume : Hydrogen by photoelectrochemical (PEC) water splitting can play a key role in future energy storage systems. In the last decade, water splitting multijunction devices could reach solar-to-hydrogen efficiencies of up to 19%. However, the fundamental loss mechanisms along the device interfaces are still not fully understood and impede further efficiency improvement. In order to address the charge transfer losses at the electrochemical interface, we focus on the electronic passivation of the photoabsorber system and its interaction with molecular water. For that purpose, we investigate the surface reconstructions of p-InP(100) by low energy electron diffraction (LEED) and their electronic structure using X-ray photoemission spectroscopy (XPS) as well as monochromatic ultraviolet photoelectron spectroscopy (UPS). Subsequently, water from the gas phase is stepwise adsorbed on the surfaces at cryogenic temperatures and the evolution of the electronic structure is examined with respect to chemical composition, hydroxylation and charge transfer. Experimentally, we found a strong Fermi level pinning at the clean surface. According to our theoretical DFT calculations, Phosphorous dangling bonds lead to partially occupied mid-gap states at the surface causing the pinning level. In this study, the impact of these Phosphorous dangling bonds on the water adsorption behavior of P-rich InP is investigated. We present our model experiment of the semiconductor/electrolyte interface and compare our experimental findings to our DFT calculations.

Authors : Wenchao Yang, Safakath Karuthedath, Catherine S. P. de Castro, Julien Gorenflot, Frederic Laquai
Affiliations : King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), Thuwal 23955-6900, Kingdom of Saudi Arabia

Resume : The Long exciton diffusion length (Ld) is revealed to be a desirable feature of nonfullerene electron acceptors (NFA) utilized in organic solar cells by exciton-exciton annihilation measurements. In order to verify and explain the experimental Ld values, we employed Kinetic Monte Carlo (KMC) method to simulate the transient absorption (TA) spectroscopy kinetics in pristine NFA materials such as ITIC, IT4F and ITM. The photogenerated singlet excitons were assumed to transport through hopping in a cubic lattice with Gaussian energetic disorder, and the hopping rates given by the Forster resonant transfer mechanism. Through reproduction of the experimental TA kinetics, the hopping prefactor and the energetic disorder were determined, with which the exciton diffusion lengths were further calculated using the KMC method, and the results turn out to be able to approximate the experimental values well. It is found that the energetic disorder in all the simulated NFA materials are ubiquitously around or below 50 meV, which contributes to the long exciton diffusion length in NFA. This work also establishes a theoretical framework for predicting exciton diffusion lengths and estimating the exciton transport parameters which are difficult to determine via experimental measurements.

Authors : Sanjay Jatav,1 Marcel Herber,1 Hongxiao Xiang,1 Junying Liu,1 and Eric H. Hill 1,2
Affiliations : 1 Institute of Physical Chemistry, University of Hamburg, Hamburg 20146, Germany 2 The Hamburg Centre for Ultrafast Imaging (CUI), Hamburg 22761, Germany

Resume : Bi2MoO6 is the simplest member of the Aurivillius group and has been lately studied for its photocatalytic activity. An anionic discoidal nanoclay was organically modified and used to template the growth of Bi2MoO6. The organically-modified clay interface templated Bi2MoO6 crystal growth along the [010] direction, resulting in the formation of clay-Bi2MoO6 hybrids terminating in {100}-facets of Bi2MoO6. These {100}-faceted Bi2MoO6-clay hybrids exhibited enhanced and instantaneous adsorption of both cationic and anionic dyes from their aqueous solutions, compared to pristine Bi2MoO6 nanoparticles and other clay-based composites. These dye-laden composite particles sediment, rendering their recovery trivial. Moreover, their reuse over multiple cycles can be achieved by photocatalytically degrading the adsorbed dye. [1] Furthermore, templating growth using a cationic clay-like template, such as layered double hydroxides, provided a similar composite which selectively sequestered anionic dyes from aqueous solution. [2] Further improvements to the adsorption performance of clay-Bi2MoO6 hybrids could also be accomplished by encapsulating them with a thin shell of crosslinked polymers, in which crosslinker amount and polymer blend were optimized for ideal adsorption. The removal of dissolved molecular species under flow conditions was attained by depositing these polymer-particle composites on filtration membranes. The repeated reuse of these membranes was also rendered possible by photocatalytically degrading the adsorbed dye, showing that such materials have great promise in anti-fouling water filtration membranes. [3] In summary, surface modification and choice of template particles provided a means to tune the adsorptivity and selectivity of Bi2MoO6 composites. References [1] S. Jatav, J. Liu, M. Herber and E. H. Hill, ACS Appl. Mater. Interfaces, 2021, 13, 16, 18713-18723. [2] S. Jatav, et al., unpublished work. [3] S. Jatav, M. Herber, H. Xiang and E. H. Hill, ACS Appl. Mater. Interfaces, 2022.

Authors : Nicolas P. L. Magnard1, Andrea Kirsch1, Olivia Aalling-Frederiksen1, Baiyu Wang1, Tobias M. Nielsen1, Mikkel Juelsholt2, Kirsten M. Ø. Jensen1
Affiliations : 1. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark 2. Currently affiliated to Departments of Materials and Chemistry, University of Oxford, Parks Road, Oxford OX1 3PH, UK

Resume : Manganese oxides can adopt several stochiometries thanks to the relative stability of the Mn ion in oxidation states +2, +3 and +4, and accommodate cations of different sizes, leading to a range of different layered and tunneled crystal structures. [1, 2] On top of that, structural defects such as De Wolff disorder and micro twinning can lead to the formation of defect-driven phases such as γ-MnO2 [3] which is an intergrowth of pyrolusite β-MnO2 and ramsdellite R-MnO2. Each of these phases have distinct properties, and synthetic control of polymorph formation is crucial. Here, we use in situ X-ray total scattering and PDF analysis supported by in situ XANES to study the formation mechanism leading to different manganese oxide polymorphs during hydrothermal synthesis. PDF analysis allows to follow structural changes all the way from the precursors in solution to the final product. We show that by changing the ratio between manganese(II) salt and oxidizer, it is possible to not only select between R, γ-, β- and α-MnO2, but more importantly the formation mechanism differs as well. Furthermore, we show that these processes involve intermediate manganese oxido-clusters, structurally similar to those found in nature or in molecular magnets,[4, 5] which act as building blocks in the formation of the crystalline nanoparticles. 1. Fortunato, J., et al., Surveying manganese oxides as electrode materials for harnessing salinity gradient energy. 2020. 54(9): p. 5746-5754. 2. Robinson, D.M., et al., Photochemical water oxidation by crystalline polymorphs of manganese oxides: structural requirements for catalysis. J Am Chem Soc, 2013. 135(9): p. 3494-501. 3. Hill, L.I. and A. Verbaere, On the structural defects in synthetic γ-MnO2s. Journal of Solid State Chemistry, 2004. 177(12): p. 4706-4723. 4. Yano, J. and V.J.C.r. Yachandra, Mn4Ca cluster in photosynthesis: where and how water is oxidized to dioxygen. 2014. 114(8): p. 4175-4205. 5. Charalambous, M., et al., [Mn14] “Structural Analogues” of Well-Known [Mn12] Single-Molecule Magnets. 2018. 2018(35): p. 3905-3912.

11:00 Coffee Break    
Doped semiconductors and catalysis : F. Ruffino
Authors : Federico Giuffrida 12, Lucia Calcagno 1, Giuliana Impellizzeri 2, Sergio Battiato 1 and Massimo Zimbone 2
Affiliations : 1) Dipartimento di Fisica e Astronomia, University of Catania 2) CNR-IMM Catania University, Via S. Sofia, 64, 95124, Catania, Italy

Resume : Titanium dioxide (TiO2) is considered a reference standard material for photocatalysis: it is widely used in environmental as well as green energy field. The most important applications span from hydrogen evolution, self-cleaning surface and water/air purification. TiO2 takes also advantage of earth-abundance and low cost which make it easily available and industrially attractive. A plethora of structures or film morphologies were studied in literature running from nanotubes, nanofibers, nanoparticles and nanowires (NWs) depending on the targeted application. Anyhow, all these structures display a high surface/volume ratio, favouring the interaction with the external environment. An interesting structure to be used in the catalysis is represented by NWs because they show high activity in the decontamination of organic pollutants in water and they can be firmly anchored to a surface. In recent years, we developed a seed-assisted thermal-oxidative synthesis of TiO2-NW, in presence of Au as a co-catalyst. This technique is robust, easy, scalable and allows to realise high-quality NWs with low external contamination, as well as, easy control of film growth. The further step in tailoring the properties of the grown nanowires is the doping. In the present paper, we investigate the doping of the NWs by Fe and Cr obtained by ion implantation. Some samples were implanted with Fe and Cr ions to investigate the effect of co-doping. Due to the ionic nature of the Ti and O bound, the doping of the TiO2 is a complex process heavily influenced by the presence of vacancies, as well as temperature and environment. In our case, dopant ions were implanted into Ti layer before the oxidation process and thus before the growth of the NWs. We implanted with Fe or Cr ions and thus we also realised samples co-doped with Fe and Cr ions. The crystalline phase, surface morphology, structural and photo-electro-chemical properties of doped TiO2 NWs grown with thermal-oxidative synthesis are investigated. We paid particular attention to the wetting properties of the surface and photocatalytic activity in the oxidation of contaminants in water.

Authors : Margot Jacquet,a* Silvio Osella,b Ersan Harputlu,c Barbara Pałys,d Monika Kaczmarek,b Ewa K. Nawrocka,e Adam A. Rajkiewicz,f Marcin Kalek,f Paweł Piotr Michałowski,g Bartosz Trzaskowski,b Gokhan C. Unlu,h Wojciech Lisowski,i Marcin Pisarek,i Krzysztof Kazimierczuk,e Kasim Ocakoglu,c Agnieszka Więckowskaj and Joanna Kargula*
Affiliations : a Solar Fuels Laboratory, Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland. b Chemical and Biological Systems Simulation Lab, Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland. c Department of Engineering Fundamental Sciences, Faculty of Engineering, Tarsus University, 33400, Tarsus, Turkey. d Faculty of Chemistry, University of Warsaw, Pasteur str. 1, 02-093 Warsaw, Poland. e Laboratory of NMR Spectroscopy, Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland. f Laboratory of Chemical Synthesis Methodology, Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland. g Łukasiewicz Research Network – Institute of Microelectronics and Photonics, Aleja Lotników 32/46, 02-668 Warsaw, Poland. h Department of Biomedical Engineering, Pamukkale University, TR-20070 Denizli, Turkey. i Institute of Physical Chemistry, Polish Academy of Science, 01-224, Warsaw, Poland. j Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.

Resume : The design of robust and cost-effective smart materials requires a rational chemical nanoengineering to afford an efficient final device covering a wild range of possible applications in electronics, medicine, catalysis, photovoltaic, etc. While different strategies have been used depending on the targeted architecture, a common important factor is the development of viable and reproducible nanodevices that are easily manufactured and carry a high potential for industrial application. Recently, a powerful methodology based on the electrografting of diazonium salts has attracted a great deal of attention due to its numerous advantages, such as a rapid and efficient functionalization process, a universal approach for various materials and proven enhanced stability of the covalent bonding. Additionally, several studies on graphene-based materials reveal that the covalent attachment of aryl groups via the above approach could lead to additional beneficial properties of this versatile material including improved conductivity, asymmetric conductance and magnetism. In this context, we report in this work the development of covalently linked metalorganic wires on two transparent, cheap, and conductive materials: fluorine-doped tin oxide (FTO) and FTO/single-layer graphene (FTO/SLG). The wires are terminated with nitrilotriacetic acid (NTA) metal complexes which are universal molecular anchors to immobilize His6-tagged proteins, such as biophotocatalysts and other types of redox-active proteins of great interest in biotechnology, optoelectronics and artificial photosynthesis. We show for the first time that the covalent grafting of diazonium salt precursor on two different electron-rich surfaces leads to the formation of the molecular wires that promote the p-doping resulting in a significantly enhanced unidirectional cathodic photocurrent up to 1 µA·cm-2. Density functional theory modeling reveals that the exceptionally high photocurrent values are due to two distinct mechanisms of electron transfer originating from different orbitals/bands of the diazonium-derived wires depending on the nature of the chelating metal redox center (Co2+ or Ni2+). Importantly, the novel metalorganic interfaces reported here offer an effective means of minimizing back electron transfer, which is essential for the maximization of solar conversion efficiency.

Authors : Daniel Aguilar-Ferrer, Igor Iatsunskyi, Sergio Moya, Mikhael Bechelany and Emerson Coy
Affiliations : Daniel Aguilar-Ferrer1,2, Igor Iatsunskyi1, Sergio Moya3, Mikhael Bechelany2, Emerson Coy1 1 NanoBioMedical Centre, Adam Mickiewicz University, Wszechnicy Piastowskiej 3, 61-614, Poznan, Poland. 2 Institut Europeen des Membranes, IEM, UMR 5635, Univ Montpellier, ENSCM, CNRS, 34730 Montpellier, France 3 Centre for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo Miramon 182 C, 20014 Donostia-San Sebastian, Spain

Resume : Localised surface plasmon resonance (LSPR) presented by gold nanorods (AuNRs) has been proved to be used in different applications such as photoredox catalysis, plasmon-enhanced spectroscopy, biomedical technologies, and optoelectronic devices. Here, a hybrid nanoplatform has been synthesized by combining AuNRs and polydopamine (PDA). The synthesis process is divided in three main steps, starting from a seed-mediated growth followed by the substitution of the capping agent with poly(ethylene glycol) methyl ether thiol (PEG), and finally, by adding the PDA precursor, creation of the final PDA cover.. Several AuNRs/PDA were synthesized with average shell thicknesses going from ≈ 4 nm to ≈ 30 nm showing LSPR values in the range between 920 nm and 800 nm. The photocatalytic study was carried out for three different samples (AuNRs/PDA1, AuNRs/PDA2, and AuNRs/PDA3) towards Rhodamine 6G (Rh6G) degradation showing for all situations better performance than bare AuNRs and bare PDA nanoparticles. Within the three samples, the highest performance was achieved by AuNRs/PDA1 which presented the thicker PDA shell (30.45 ± 4.9 nm) with almost 35% of Rh6G initial concentration depleted in 1h for a relatively small concentration of the catalyst ([AuNRs] = 9815.60 µg/L). As final conclusion, different shell thickness AuNRs/PDA have been synthesized and could be used as a model for enhanced organic dye photocatalysis.

Authors : Mattia Pizzone 1,2; Maria Grazia Grimaldi 2; Antonino La Magna 1; Neda Rahmani 3; Silvia Scalese 1; Jost Adam 3; Rosaria A. Puglisi 1.
Affiliations : 1 Istituto per la Microelettronica e Microsistemi (IMM), Consiglio Nazionale delle Ricerche (CNR), Catania, Italy; 2 Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università degli Studi di Catania, Italy; 3 SDU Centre for Photonics Engineering, University of Southern Denmark (SDU), Denmark.

Resume : The Molecular Doping process is based on the deposition of a self-assembled layer of dopant-containing molecules over the surface of a semiconductor substrate. The dopant atoms are released inside the substrate during the successive drive-in annealing step. In the typical deposition conditions, the formation of the layer is in the order of the tens of minutes, allowing for a fast dopant source layer formation. Even if the process is well controlled and its doping efficiency already demonstrated [Nanomaterials 2021, 11, 1899. https://], however the early stages are very interesting to study because they reveal the micro- and nano- features of the final self-assembled layer, not known so far. Our previous works suggest that molecular clusters form during the early nucleation phase, and they successively grow into self-assembled layers on the substrate. Little is known about the nucleation kinetics influence on the molecular clusters’ morphology and the final morphological properties of the layers. In this work, we monitor the nucleation and coalescence process, in terms of molecular clusters density, size and shape, of diethyl-propyl phosphonate on silicon at different deposition conditions through a high-resolution morphological characterization. We correlate the results to the electrical characteristics of the final doped samples identifying the role of the clusters characteristics, and how these impact the electrical properties.

13:00 Lunch Break    
Advanced Characterization II : J. Adam
Authors : Chawki Awada*, Nagih Shaalan, Chahinez Dab, Francesco Ruffino
Affiliations : Department of Physics, College of Science, King Faisal University, P.O. Box: 400, Al‑Ahsa 31982, Saudi Arabia. Department de biologie, chimie et géographie, Université du Québec à Rimouski, 300 allée des Ursulines, Rimouski (Qc), Canada, G5L 3A1, Canada Dipartimento di Fisica e Astronomia “Ettore Majorana”-Università di Catania and MATIS CNR-IMM, via S. Sofia 64, 95123 Catania, Italy

Resume : SERS is more applied to study solid-state materials or liquid, i.e. solution. However, using SERS to detect molecules in the gas phase is fewest. Indeed, handling and preparing gas samples are difficult, in addition, the gas medium is more diluted even at high concentrations. The latter leads to a small cross section of collected signal. Despite these difficulties, there is more need for new sensors based on SERS to study the gas adsorption properties onto the interface gas/solid, e.g., to study the toxicity degree of some gases such NO2. NO2 is an irritant gas that will cause lachrymation, coughing, respiratory distress, increases in methemoglobin (MetHb) levels, and lung edema.16 In fact, understanding the mechanism of adsorption of NO2 will provide more insights and information on the interaction properties of NO2. That’s why a development of a new method of detection such as SERS is very important. In early studies, SERS has shown its capability to monitor the photochemical reaction of N2O gas driven by hot electron of localized surface plasmon resonances (LSPRs) on the surface of metallic nanostructures. In this work, we report for the first time a steady-state detection method of 50 ppm of nitrogen dioxide (NO2) gas in a polyethylene (PET) bag using surface-enhanced Raman spectroscopy (SERS). SERS was performed on different shapes of gold nanostructures; gold nanostars (GNS) and nanoporous gold film (NPG). In both, we detected the vibrational modes assigned to the adsorbents of NO2 molecules such as NO2, NO, NO3-, N2O3, and N2O5. The generation of the adsorbents is due to the photo-chemical reaction driven by the hot electron generated at the surface of gold nanostructures. Our funding is supported by a finite element simulation excluding the plasmon induced photo-thermal process due to the long duration of excitation compared to the duration of SERS measurement. The mechanism of NO2 photochemical reactions is explained, confirming the adsorbtion of NO2 molecules on the gold surface towards their oxygen atoms.

Authors : Stefano Boscarino 1-2, Maria Censabella 1-2, Melanie Micali 1-2, Marco Russo1, Antonio Terrasi 1-2, Maria Grazia Grimaldi 1-2, Francesco Ruffino1-2
Affiliations : 1 Dipartimento di Fisica e Astronomia “Ettore Majorana” Università di Catania, Via S. Sofia 64, 95123, Catania, Italy; 2 CNR-IMM, Via S. Sofia 64, 95123, Catania, Italy

Resume : Photovoltaics is an important and strategic topic in the field of renewable and sustainable energy. The light harvesting performance of a solar cell is a crucial factor which heavily affects its efficiency [1,2]. In this context, metal nanostructures, thanks to their unique properties related to their small physical dimension, large surface/volume ratio and surface properties, have gained increasing attention as one of the best solution to ensure sunlight absorption enhancement by surface plasmon resonance (SPR) [3]. Although many studies and scientific researches have been done in this fields, mainly with gold and silver nanostructures, one of the challenges is to integrate Cu nanostructures in solar cells in order to enhance the solar cell efficiency over NUV-visible-NIR spectrum. Herein Cu Nanostructures are obtained by solid-state dewetting of 9 nm Copper layer (dry) or by ablating Copper target, using a nanosecond pulsed laser at 1064 nm, in acetone and Isopropyl alcohol (wet). Once the Cu nanostructures were realized, they were embedded in Aluminum-doped Zinc Oxide (AZO) layer or Zirconium-doped Indium Oxide (IZrO) layer. The TCO/Cu nanostructures/TCO system were synthetized with all combinations of AZO and IZrO as top and bottom layers. Cu nanostructures morphology (shape and size) were investigated as a function of the involved method of synthesis and key parameters: In SSD process the morphology was studied as a function of the annealing temperature, ranging from 300 to 500°C in N2, while in laser ablation as a function of the used liquid environment. The electrical, optical and morphological properties of the systems were investigated by SEM, Rutherford backscattering spectrometry, image analysis processing, four-point collinear probe method, UV-Vis-NIR spectrophotometer. The aim is to compare the two fabrication methods of Cu nanostructures and select the best sequence of TCOs in order to achieve a system working in solar cell as a plasmonic and conductive interface. The main differences exhibited by wet and dry processes were in shape and size of the Cu nanostructures, dewetting in nitrogen produces faceted nanoparticles with an average size below 150 nm, while laser ablation originates spherical and smaller nanoparticles, below 50 nm. Dry system, made of only AZO, underwent to thermal annealing improves the electrical properties compared to wet system, sheet resistance of 103 vs 106 Ω/sq respectively; while dry system shows a maximum transmittance of 89,7% at 697 nm compared to wet system in acetone, 88.4% at 647 nm, and in Isopropyl alcohol, 86.9% at 686 nm. Moreover, wet systems show higher trasmittance in NUV. Dry and wet systems made of only IZrO, thanks to this TCO, improves the electrical properties until to sheet resistance lower than 200 Ω/sq; while the optical properties suffered of low transmittance in VIS range with a maximum of 70% at 800 nm. Finally, hybrid system with AZO and IZrO, showed a conductivity dominated by IZrO, with a sheet resistance of 200-400 Ω/sq, while the optical properties showed a dependence on the sequence of the top and bottom TCOs. We believe that these results, with low-cost and simple-fabricated method, supply pratical data for a better utilization of cost-effective Cu nanostructures to improve the light harvesting performance of photovoltaic devices. References 1. De Aberasturi, D. J.; Serrano-Montes, A.B.; Liz-Marzán, L.M. Modern Applications of Plasmonic Nanoparticles: From Energy to Health. Adv. Optical Mater. 2015, 3, 602-617. 2. Parveen, F.; Sannakki, B.; Mandke,M.V.; Pathan, H.M. Copper nanoparticles: Synthesis methods and its light harvesting performance. Solar Energy Materials and Solar Cells 2016, 144, 2016, Pages 371-382. 3. Liu, J.; He, H.; Xiao, D.; Yin, S.; Ji, W.; Jiang, S.; Luo, D.; Wang, B.; Liu, Y. Recent Advances of Plasmonic Nanoparticles and their Applications. Materials 2018, 11, 1833.

Authors : Haoqing Ning(1), Soham Mukherjee(2) , Donatas Zigmantas(3), Andrew J Musser(2), Artem A. Bakulin(1)
Affiliations : (1) Department of Chemistry and Centre for Processable Electronics , Imperial College London, London W12 0BZ,United Kingdom (2) Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA (3) Donatas,Zigmantas- Division of Chemical Physics and NanoLund, Lund University, P.O. Box 124, 22100 Lund, Sweden

Resume : Singlet fission is an internal conversion process in which a high-energy photoexcited singlet can degenerate into two low-energy triplets forming a triplet pair. Investigating the energy transfer pathways of the excited states during the singlet fission is important for the design of efficient fission-based solar cells. Two typical mechanisms have been proposed in the literature to describe singlet fission. One mechanism suggests a direct transition from singlet to triplet pair, while the other mechanism suggests that there is an intermediate multiexciton bounded T..T state during the transition[1]. However, multiexcitonic T..T states are considered optically dark and difficult to be directly verified by conventional spectroscopy. Here we use two-dimensional coherent electronic spectroscopy (2DES) to study singlet fission dynamics in two pentacene dimer derivatives (DP-TIPS and DP-MES). In both molecules, the population dynamics suggest the presence of the intermediate triplet pair (T..T) during the intramolecular singlet fission which happens on the timescale ~200 fs. Due to the mixing of singlet exciton and multiexcitonic T..T state[2], we can further locate the energy of the T..T state through beating maps of selected vibrational mode, and we provide Liouville pathway analysis to all beating peaks which relate to the transition from singlet to T..T pair. Our experiment demonstrates the prevalence of bound triplet pair states as an intermediate in the intramolecular singlet fission system. The result reveals a connection between the presence of multiexciton intermediate states near resonant with S and a more rapid fission rate. [1] Lukman, S. et al. Nat. Commun. 2016,7, 13622 [2] Bakulin, A. et al. Nat. Chem 2016, 8, 16?23

Authors : Hye-Ji Kim, Jin-Su Kim, Seung-Yeol Jeon, Woong-Ryeol Yu
Affiliations : Department of Materials Science and Engineering, Seoul National University; Department of Materials Science and Engineering, Seoul National University; Korea Institute of Science and Technology (KIST); Department of Materials Science and Engineering, Seoul National University

Resume : Liquid Crystal Elastomers (LCEs) are lightly crosslinked polymers incorporated with rigid and anisotropic liquid crystal molecules (mesogens). The liquid-crystalline ordering of such mesogen in nematic monodomain LCEs brings about reversible shape memory performance by the isotropic-nematic transition. Due to this reversible shape memory behavior, LCEs are used in various applications, e.g., smart fibers, 4D printing, soft robotics, biomedical engineering, smart coatings, etc. There are two main parameters that affect the anisotropic ordering of mesogens: temperature and mechanical strain. This research was aimed to investigate degree of orientation of main-chain in LCE under both varying temperature and mechanical strain via wide angle X-ray scatterings (WAXS) analysis. LCE was synthesized by two-stage thiol-acrylate Michael addition. Mesogenic acrylate monomers (RM257, excessive acrylate 2 mol%), flexible polymer chain of 1,3-propanedithiol, and PETMP crosslinker were used. WAXS analysis was carried out to observe the anisotropic orientational behavior of mesogens in prepared LCE when various temperature and mechanical force were given. WAXS analysis revealed that as the temperature approaches Ti, isotropic-nematic phase transition temperature, the change of degree of orientation becomes more influenced by thermal energy than the mechanical strain. Dynamic mechanical analysis was also carried out to identify this inflection temperature at various temperatures, finding about 70 Celsius temperature through relaxation test. Finally, the orientational behavior of mesogens in LCE was quantitatively established as a function of temperature and mechanical strain, enabling to simulate the deformation behavior of LCE considering its microstructure.

Authors : Censabella M. (1,2), Iacono V. (1,2,3), Scandurra A. (1,2), Moulaee K. (4), Neri G. (4), Ruffino F. (1,2,3), Mirabella S. (1,2,3)
Affiliations : (1) Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, via S. Sofia 64, 95123 Catania, Italy; (2) CNR-IMM (Catania Università), via S. Sofia 64, 95123 Catania, Italy; (3) CSFNSM - Centro Siciliano di Fisica Nucleare e Struttura della Materia, Via S. Sofia 64 95123 Catania; (4) Department of Engineering, University of Messina and INSTM Research Unity, C.da Di Dio, I-98166, Messina, Italy;

Resume : Fast, selective and low-cost nitric oxide (NO) sensors are highly needed due to the harmful effects of this gas. Low temperature NO detection is as requested as challenging, requiring selective and effective catalytic processes. Metal oxides (MOx) are most widely used materials for gas sensor applications [1]. Usually, n-type semiconductors require high operating temperature (>300°C) and have low sensitivities [2]. For this reason, p-type semiconductors have been extensively studied for gas sensors. Here, we present an experimentally based CuO-NO interaction model in the 50-400 °C temperature range and a promising NO detector working at 50°C based on CuO nanoparticles (NPs) realized by pulsed laser ablation in liquid environment (PLAL) technique. Ligand-free Cu/Cu2O nanostructures produced by PLAL in deionized water and were converted into CuO NPs by 400°C annealing, and analysed by X-Ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray techniques. A chemoresistive sensor is produced by drop-casting 0.1 mL of CuO NPs suspension onto an interdigitated electrode of Pt/Al2O3 and tested in a flow-controlled test chamber. Studying the sensor response toward several gas, the highest and fastest response toward NO is obtained at 50°C. It was observed that the resistance had an opposite behaviour fluxing NO at different temperatures. Below 250°C an oxidation behaviour is recorded while above 350°C reduction takes place, with a peculiar transient regime observed at 300°C. Hence, a full model of CuO-NO interaction based on Langmuir adsorption theory is proposed and kinetics barriers has been extracted by analysing the response curves in the 50-400 °C temperature range [3]. A peculiar catalytic activity of CuO NPs emerges in combination with oxygen species absorbed at different temperature, leading to effective NO detection. The ease and scalability of CuO NPs production by PLAL and the reported fast and selective NO sensor working at 50°C open promising routes towards exploitation for massive and affordable harmful gas detection. [1] R. Malik, V. K. Tomer, Y. K. Mishra and L. Lin, Functional gas sensing nanomaterials: A panoramic view, Applied Physics Reviews 2020, 7, 021301. [2] Hou, C. Zhang, L. Li, C. Du, X. Li, X. F. Kang, W. Chen, CO gas sensors based on p-type CuO nanotubes and CuO nanocubes: Morphology and surface structure effects on the sensing performance, Talanta 2018, 188, 41-49. [3] M. Censabella, V. Iacono, A. Scandurra, K. Moulaee, G. Neri, F. Ruffino, S. Mirabella, Low temperature detection of nitric oxide by CuO nanoparticles synthesized by pulsed laser ablation. Sensors and Actuators B: Chemical, 2022, 358, 131489.

15:30 Coffee Break    
Authors : G. Biffi, S. Sansotta, H. Lechner, S. Ferrara, A. L. Cortajarena, C. Barolo, G. Oberdorfer, R. Costa, P. B. Coto
Affiliations : Consejo Superior de Investigaciones Cientificas, Centro de Fisica de Materiales (Donostia-San Sebastian, Spain); Consejo Superior de Investigaciones Cientificas, Centro de Fisica de Materiales (Donostia-San Sebastian, Spain); Graz University of Technology (Graz, Austria); Technische Universität München (Munich, Germany); CICbiomaGUNE (Donostia-San Sebastian, Spain); Università di Torino (Turin, Italy); Graz University of Technology (Graz, Austria); Technische Universität München (Munich, Germany); Consejo Superior de Investigaciones Cientificas, Centro de Fisica de Materiales, Donostia International Physics Centre (Donostia-San Sebastian, Spain)

Resume : In the field of lighting, white light-emitting-diodes (WLEDs) are increasingly regarded as a replacement for inefficient incandescent light bulbs and environmentally damaging fluorescent lamps[1]. Recently, important research efforts have been devoted to the development of inorganic LEDs, in both the design of new materials exhibiting a broadband emission[2] and the implementation of devices with architectures based on the down-conversion concept[3,4]. Both approaches, however, have shown serious limitations due to toxicity and/or unavailability of either the fluorophore or the down-converting filters, which often contain heavy metals or rare-earth elements[5]. The rising costs and ecological impact (mining/refining/toxicity) put a heavy burden on the long-term sustainability of inorganic WLEDs. An innovative, sustainable and cheap alternative is offered by the bio-LED concept[6], in which the downconverting filter is made of a fluorescent protein embedded in a polymeric matrix. In this regard , we propose a fully theoretical design of a fluorophore-protein system for applications in bio-LEDs in the low energy range of the visible spectrum, using a modified NDI chromophore and a nitrobinding type protein. The study required a quantum mechanical approach for the characterisation of the excited states of the proposed chromophore and protein docking simulations for the evaluation of the possible protein-chromophore assemblies. Subsequently, quantum mechanics/molecular dynamics calculations were performed to study the stability of the system and obtain insights in to the effects of relative ortientations of the chromophore within the protein , environment and hydrogen bonds on the spectroscopic behaviour of the system. The obtained results have been compared with and corroborated by experimental spectroscopic analysis and the applicability of the designed system has been proven by a prototype device performance and stability. Bibliography 1. Cho, J. et al., Laser and Photonics Rev., 11, 1600147 (2017). 2. a) Smith, M. D. et al., Chem. Sci., 8, 6, 4497 (2017); b) Febriansyah, B. et al., J. Mater. Chem , 8, 3, 889 (2020); c) Wu, Z. et al., J. Mater. Chem. C, 6, 1171 (2018); d) Li, D. et al., Adv. Opt. Mater., 6, 1800273 (2018). 3. Mukherjee, S. and Thilagar, P. Dyes Pigm., 110, 2 (2014). 4. Fernández-Luna, V. et al., Angew. Chemie - Int. Ed. 57, 8826 (2018). 5. a) Wei, Y., et al., Chem. Soc. Rev., 48, 310 (2019); b) Xia, Z. et al., Dalton Trans., 45, 11214 (2016); c) Qin, X. et al., Chem. Rev., 117, 4488 (2017); d) Xia, Z. and Meijerink, A.., Chem. Soc. Rev., 46, 275 (2017). 6. a) Espasa, A. et al., Nat. Commun., 11, 1 (2020); b) Weber, M. D. et al., Adv. Mater., 27, 5493 (2015); c) Fernández-Luna, V. et al., Adv. Funct. Mater., 29, 1 (2019); d) Niklaus, L. et al., Mater. Horizons, 3, 340 (2016); e) Niklaus, L. et al., Adv. Funct. Mater. 27, 1601792 (2017); f) Fresta, E. et al., Adv. Funct. Mater., 28, 1 (2018).

Authors : Xia Peng, Mario Urso, Martina Ussia, Martin Pumera*
Affiliations : 1 Future Energy and Innovation Laboratory, Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic 2 Department of Medical Research, China Medical University Hospital, China Medical University, No. 91 Hsueh-Shih Road, Taichung, Taiwan, ROC 3 Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, 03722, Seoul, Korea

Resume : Nature presents collective behavior of living organisms aiming to accomplish complex tasks, inspiring the development of cooperative micro/nanorobots. Herein, the spontaneous assembly of hematite-based microrobots with different shapes is presented. Autonomous motile light-driven hematite/Pt microrobots with cubic and walnut-like shapes are prepared by hydrothermal synthesis. We characterizied the structure and composition of the microrobots. Both microrobots show a fuel-free motion ability on the basic of photocatalysis. Because of the asymmetric orientation of the dipolar moment in the crystal, cubic hematite/Pt microrobots can self-assemble into ordered microchains. The microchains exhibit different synchronized motions under light irradiation depending on the mutual orientation of the individual microrobots during the assembly, which allow them to accomplish multiple tasks, including capturing, picking up and transporting microscale objects, microplastics in water, as well as degrading polymeric materials for environmental remediation. Such novel light-powered self-assembled microchains hold great potential toward cargo capture, transport and delivery, and wastewater remediation, which may make contribute to green energy in the future.

Authors : Wei-Hsu Hu(1,2), Camilla Vael(2,3), Matthias Diethelm(1,2), Karen Strassel(1,2), Surendra B. Anantharaman(1,2), Abdessalem Aribia(4), Marco Cremona(5), Sandra Jenatsch(3), Frank Nüesch(1,2), Roland Hany(1)
Affiliations : 1. Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers, 8600 Dübendorf, Switzerland; 2. EPFL, Institute of Materials Science and Engineering, Ecole Polytechnique Fédérale de Lausanne, Station 12, 1015 Lausanne, Switzerland; 3. Fluxim AG, Katharina-Sulzer-Platz 2, 8400 Winterthur, Switzerland; 4. Empa, Swiss Federal Laboratories for Materials Science and Technology, Thin Films and Photovoltaics, 8600 Dübendorf, Switzerland; 5. PUC-Rio, Pontifical Catholic University of Rio de Janeiro, Physics Department, Optolectronic Molecular Laboratory, 224543-970, Rio de Janeiro, Brazil;

Resume : Organic upconversion devices (OUCs) consist of an organic infrared photodetector and an organic visible light-emitting diode (OLED), connected in series. OUCs directly convert photons from the infrared to the visible and are of use in applications such as process control or imaging. Many applications require a fast OUC response speed, namely the ability to accurately detect in the visible a rapidly changing infrared signal. Here, high image-contrast, solution-processed, narrowband OUCs are reported that convert near-infrared (NIR) light at close to 1000 nm with a full-width at half maximum of 130 nm into visible light. Transient photocurrent measurements show that the response speed decreases when lowering the NIR light intensity. This is contrary to conventional organic photodetectors that show the opposite speed versus light trend. It is further found that the response speed can even decrease when increasing the driving voltage. Again, this is an unexpected result because the charge drift velocity gets faster by an enhanced electric field. To understand this surprising response speed behavior, an analysis by numerical simulation is conducted. Results show that the response speed is primarily determined by the (low) electron mobility value in the OLED. Simulations confirm that the speed indeed decreases when lowering the NIR light intensity, and an increase of the applied voltage does not necessarily increase the response speed, as would intuitively be taken for granted. Our work is the first systematic study on the response speed of OUCs. A few reported single-parameter measurements show that the response speed of OUCs so far is limited to around 10 kHz. This is much lower than the speed of organic photodetectors, for which typical cut-off frequencies are above 100 kHz. We think that the main reason for this discrepancy is the low electric field in the OUC emitter layer, which results in a low charge drift velocity, and in a lower effective electron mobility value because the mobility is electric field dependent. It thus seems that the specific device architecture sets a fundamental limit to the response speed of OUCs. Reference: Wei Hsu et al., On the response speed of narrowband organic optical upconversion devices, Adv. Optical Mater. 2022, doi:10.1002/adom.202200695.

Authors : Adil Alshoaibi a, , Shumaila Islam
Affiliations : Department of Physics, College of Science, King Faisal University, Al-Hassa, P.O. Box 400, Hofuf 31982, Saudi Arabia

Resume : Zinc oxide (zincite) decorated silica-titania nanocomposite (ZST-NC) is synthesized by sol-gel method. For dynamic pH range and fast-response fibre-optic pH sensing characteristics, a blend of phenol red, bromophenol blue, phenolphthalein, and cresol red is immobilised in ZST-NC (D/ZST-NC). A fundamental analysis revealed that ZST-NC and D/ZST-NC had crack-free morphology and thermal stability at 560 ◦C. The ZST-NC exhibited a surface roughness (Ra) 0.4 nm, a crystallite size 5 nm, and a refractive index 1.48. The D/ZST-NC revealed a Ra 0.8 nm, a crystallite size 2 nm, and a refractive index 1.49. The sensitivity of the D/ZST-NC coated optic fibre is estimated to be 15.67 counts/pH at 440 nm, with a determination coefficient (R2 ) ~99%. A high pKa ~8 and a rapid response time 0.13 s at pH 12 are observed. The prepared pH sensor displays a reversible and non-leaching behaviour, which is advantageous for applied opto-chemical pH sensing purposes.


Symposium organizers
Biplab SANYALUppsala University

Department of Physics & Astronomy, Ångströmlaboratoriet, Box-516, 75120 Uppsala, Sweden

+46 18 4713624
Francesco RUFFINOUniversity of Catania

Department of Physics and Astronomy “Ettore Majorana”, via S. Sofia 64, 95124, Catania, Italy

Jost ADAM (Main Organizer)Mads Clausen Institute

Computational Materials Group, Photonics Engineering, Campusvej 55, 5230 Odense M, Denmark

+45 6550 8209
Sangeeta SHARMAMax-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy

Max-Born-Straße 2A, 12489- Berlin, Germany

+49 30 6392 1350