A novel S-scheme 3D ZnIn2S4/WO3 heterostructure for improved hydrogen production under visible light irradiation

In-plane epitaxial growth of ZnIn2S4 nanosheets on the surface of hexagonal phase WO3 nanorods was achieved by a facile solvothermal method. The unique 3D heterostructure not only enlarged the specific surface area, but also red-shifted the absorption edge from 381 to 476 nm to improve the light harvesting ability, which largely enhanced the photocatalytic hydrogen evolution. The H2 pro-duction rate of the best performing ZnIn2S4/WO3 photocatalyst (ZIS-2.5/W, the material with a molar rate of ZnIn2S4 (ZIS) to WO3 (W) of 2.5) was 300 iimol center dot g-1 center dot h-1, around 417 times and 2 times higher than the rates of pristine WO3 and ZnIn2S4, respectively. The apparent quantum efficiency for ZIS-2.5/W composite was up to 2.81% at 400 nm. Based on the difference in Fermi levels between WO3 and ZnIn2S4, and the distribution of the redox active sites on WO3/ZnIn2S4 heterostructure, a S-scheme electron transfer mechanism was proposed to illustrate the improved photocatalytic activity of WO3/ZnIn2S4 heterojunction, which not only stimulated the spatial separation of the photogenerated charge carriers, but also maintained the strong reduction/oxidation ability of the photocatalyst. (c) 2022, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.