Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/111621
Title: Revisiting the Chemical Stability of Germanium Selenide (GeSe) and the Origin of its Photocatalytic Efficiency
Authors: Boukhvalov, D. W.
Nappini, S.
Vorokhta, M.
Menteş, T. O.
Piliai, L.
Panahi, M.
Genuzio, F.
De Santis, J.
Kuo, C. -N.
Lue, C. S.
Paolucci, V.
Locatelli, A.
Bondino, F.
Politano, A.
Issue Date: 2021
Publisher: John Wiley and Sons Inc
Wiley
Citation: Revisiting the Chemical Stability of Germanium Selenide (GeSe) and the Origin of its Photocatalytic Efficiency / D. W. Boukhvalov, S. Nappini, M. Vorokhta et al. // Advanced Functional Materials. — 2021. — Vol. 31. — Iss. 50. — 2106228.
Abstract: Recently, germanium selenide (GeSe) has emerged as a promising van der Waals semiconductor for photovoltaics, solar light harvesting, and water photoelectrolysis cells. Contrary to previous reports claiming perfect ambient stability based on experiments with techniques without surface sensitivity, here, by means of surface-science investigations and density functional theory, it is demonstrated that actually both: i) the surface of bulk crystals; and ii) atomically thin flakes of GeSe are prone to oxidation, with the formation of self-assembled germanium-oxide skin with sub-nanometric thickness. Surface oxidation leads to the decrease of the bandgap of stoichiometric GeSe and GeSe1−x, while bandgap energy increases upon surface oxidation of Ge1−xSe. Remarkably, the formation of a surface oxide skin on GeSe crystals plays a key role in the physicochemical mechanisms ruling photoelectrocatalysis: the underlying van der Waals semiconductor provides electron–hole pairs, while the germanium-oxide skin formed upon oxidation affords the active sites for catalytic reactions. The self-assembled germanium-oxide/germanium-selenide heterostructure with different bandgaps enables the activation of photocatalytic processes by absorption of light of different wavelengths, with inherently superior activity. Finally, it is discovered that, depending on the specific solvent-GeSe interaction, the liquid phase exfoliation of bulk crystals can induce the formation of Se nanowires. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH
Keywords: 2D MATERIALS
CATALYSIS
DENSITY FUNCTIONAL THEORY CALCULATIONS
GERMANIUM SELENIDE
SURFACE SCIENCE
CATALYTIC OXIDATION
CHEMICAL STABILITY
CRYSTALS
DENSITY FUNCTIONAL THEORY
ENERGY GAP
GERMANIUM OXIDES
LIGHT
OXIDATION
PHOTOCATALYTIC ACTIVITY
SEMICONDUCTING GERMANIUM
VAN DER WAALS FORCES
AMBIENT STABILITY
CATALYTIC REACTIONS
PHOTO-ELECTROCATALYSIS
PHOTOCATALYTIC EFFICIENCY
PHOTOCATALYTIC PROCESS
PHYSICO-CHEMICAL MECHANISMS
SURFACE OXIDATIONS
SURFACE SENSITIVITY
SELENIUM COMPOUNDS
URI: http://hdl.handle.net/10995/111621
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 85114918221
PURE ID: 29069436
ISSN: 1616-301X
metadata.dc.description.sponsorship: A.P. thanks CERIC-ERIC for the access to the NAP-XPS facility and Elettra Sincrotrone Trieste for providing access to its synchrotron radiation facilities. S.N. and F.B. acknowledge funding from EUROFEL project (RoadMap Esfri), J.D.S., V.P., and A.P. thank Maria Giammatteo for technical support in SEM experiments at Microscopy Centre of University of L'Aquila. Open access funding provided by Universita degli Studi dell'Aquila within the CRUI-CARE Agreement.
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