期刊
ADVANCED MATERIALS
卷 33, 期 14, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.202006957
关键词
catalysis; dichalcogenides; hydrogen evolution reaction; phase transitions; photoelectron spectroscopy
类别
资金
- FLAG-ERA Graphene Basic Research 2 2017 in project LaMeS DFG [400335214]
- Carl Tryggers Foundation (CTS), Sweden
- ERC [669531 EDAX]
- Projekt DEAL
Visible light is demonstrated to induce a transient metallic surface layer on p-doped 2H-MoS2, leading to a phase-transition of the surface layer. This light-induced phenomenon may increase charge mobility on the surface, enhancing photocatalytic reactions on 2H-MoS2. The discovery of this mechanism provides a new pathway for controlling surface properties of semiconductors.
Visible light is shown to create a transient metallic S-Mo-S surface layer on bulk semiconducting p-doped indirect-bandgap 2H-MoS2. Optically created electron-hole pairs separate in the surface band bending region of the p-doped semiconducting crystal causing a transient accumulation of electrons in the surface region. This triggers a reversible 2H-semiconductor to 1T-metal phase-transition of the surface layer. Electron-phonon coupling of the indirect-bandgap p-doped 2H-MoS2 enables this efficient pathway even at a low density of excited electrons with a distinct optical excitation threshold and saturation behavior. This mechanism needs to be taken into consideration when describing the surface properties of illuminated p-doped 2H-MoS2. In particular, light-induced increased charge mobility and surface activation can cause and enhance the photocatalytic and photoassisted electrochemical hydrogen evolution reaction of water on 2H-MoS2. Generally, it opens up for a way to control not only the surface of p-doped 2H-MoS2 but also related dichalcogenides and layered systems. The findings are based on the sensitivity of time-resolved electron spectroscopy for chemical analysis with photon-energy-tuneable synchrotron radiation.
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