Solid-state Z-scheme assisted hydrated tungsten trioxide/ZnIn2S4 photocatalyst for efficient photocatalytic H2 production

Abstract

Efficient water splitting for H2 evolution over semiconductor photocatalysts is highly attractive in the field of clean energy. It is of great significance to construct heterojunctions, among which the direct Z-scheme nanocomposite photocatalyst provides effective separation of photo-generated carriers to boost the photocatalytic performance. Herein, Z-scheme hydrated tungsten trioxide/ZnIn2S4 is fabricated via an in-situ hydrothermal method where ZnIn2S4 nanosheets are grown on WO3⋅xH2O. The close contact between WO3⋅0.5H2O and WO3⋅0.33H2O as well as ZnIn2S4 improve the charge carrier separation and migration in the photocatalyst, where the strong reducing electrons in the conduction band of ZnIn2S4 and the strong oxidizing holes in the valence band of WO3⋅0.33H2O are retained, leading to enhanced photocatalytic hydrogen production. The obtained WO3⋅xH2O/ZnIn2S4 shows an excellent H2 production rate of 7200 μmol g−1 h−1, which is 11 times higher than pure ZnIn2S4. To the best of our knowledge, this value is higher than most of the WO3-based noble metal-free semiconductor photocatalysts. The improved stability and activity are attributed to the formation of the Z-scheme heterojunction, which can markedly accelerate the interfacial charge separation for surface reaction. This work offers a promising strategy towards the design of an efficient Z-scheme photocatalyst to suppress electron–hole recombination and optimize redox potential.