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

Abstract

Abstract Efficient water splitting for H 2 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/ZnIn 2 S 4 is fabricated via an in-situ hydrothermal method where ZnIn 2 S 4 nanosheets are grown on WO 3 ⋅ x H 2 O. The close contact between WO 3 ⋅0.5H 2 O and WO 3 ⋅0.33H 2 O as well as ZnIn 2 S 4 improve the charge carrier separation and migration in the photocatalyst, where the strong reducing electrons in the conduction band of ZnIn 2 S 4 and the strong oxidizing holes in the valence band of WO 3 ⋅0.33H 2 O are retained, leading to enhanced photocatalytic hydrogen production. The obtained WO 3 ⋅ x H 2 O/ZnIn 2 S 4 shows an excellent H 2 production rate of 7200 μ mol g −1 h −1 , which is 11 times higher than pure ZnIn 2 S 4 . To the best of our knowledge, this value is higher than most of the WO 3 -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.