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Spyros N. Yannopoulos: Facile, large area growth of mono- and few-layer MX2 (M: Mo, W; X: S, Se) with high catalytic performance by controlled chalcogenation of a transition metal foil

posted 3 Aug 2016, 06:46 by info admin
Spyros N. Yannopoulos, Aspasia Antonelou, George Syrrokostas
Foundation for Research and Technology Hellas – Institute of Chemical Engineering Sciences (FORTH/ICE-HT), P.O. Box 1414, GR-26504, Rio-Patras, Greece

Two-dimensional (2D) crystals have attracted vivid research interest over the last decade owing to their unique properties in comparison to their bulk counterparts. Besides single-atom thick 2D crystals such as graphene, polyhedral thick materials whose layer thickness is dictated by the size of structural unit, i.e. transition metal di-chalcogenides, TMDCs (MoX2, WX2, etc., with X: S, Se, Te) can be prepared in mono- and few-layer thickness by various methods. 
Whilst the vast majority of the spectacular properties of TMDCs emerging as the number of monolayers decreases are so far considered adequately understood, interest is focused now on commercialization and viable applications of these materials. Essentially, the prerequisite to achieve this is the facile, reliable and low-cost preparation of substrate-wide films of controlled thickness. Here, we show that preparation of substrate-wide MoX2 is achievable with easy control down to the monolayer thickness [1]. The growth takes place via soft chalcogenation of commercially available Mo foils without any pretreatment by a process that is scalable to any substrate dimension. The quality of the prepared MX2 layers on such flexible substrates is characterized by Scanning Electron Microscopy, Raman scattering and X-ray photoelectron spectroscopy. In addition, the catalytic activity of MX2 as counter electrodes (CE) has been evaluated demonstrating outstanding performance, similar to that of the more costly Pt-based CEs.

Spyros Yannopoulos obtained his PhD from the University of Patras (1997) on the structure and dynamics of non-crystalline solids. He is currently a Principal Researcher at FORTH/ICE-HT specializing on advanced amorphous materials and nanomaterials. His research activities are focused on a molecular-based level understanding of materials’ properties and phenomena in hard and soft condensed matter employing experimental and (recently) computational methods. Main research activities include studies of disordered solids (glasses, amorphous films), photonic applications of amorphous semiconductors, nanostructured materials with specific functionalities (nanostructured oxides for nanophotonics, hydrogen evolution, energy conversion applications and gas sensing). He has been involved in the exploration of laser-assisted methods for graphene synthesis using a variety of organic and inorganic (carbides) substances. Recent activities include also the fabrication of 2-D crystals (TMDChs) and the study of their catalytic activities in solar cell devices. He has published 118 papers in peer-reviewd journals and 12 chapters in international books.