Robust S-scheme hierarchical Au-ZnIn2S4/NaTaO3: Facile synthesis, superior photocatalytic H2 production and its charge transfer mechanism

Designing Step-scheme (S-scheme) heterojunction with the directional charge transfer pathway has been considered as a promising strategy for realizing effective spatial separation of photo-generated carriers in a photocatalytic system by utilizing broadband solar energy. Herein, the novel and ternary S-scheme heterojunction photocatalysts were fabricated by embedding Au nanoparticles (NPs) on the surface of ZnIn2S4/NaTaO3 composites through a facile two-step hydrothermal method for the first time. As expected, it showed an enhanced hydrogen evolution rate of 11404 μmol g-1 h-1, which was approximately 58 and 10 times higher than that of the pristine NaTaO3 nanocubes (197 μmol g-1 h-1) and ZnIn2S4 microspheres (1180 μmol g-1 h-1) under simulated sunlight irradiation, respectively. An intimate heterojunction interface as well as Au nanoparticles as electron reservoir and reactive sites, which enhanced light absorption capacity and accelerated charge carrier separation, was answerable to the huge promotion in the photocatalytic performance. Most notably, XPS, EPR analysis and density functional theory (DFT) calculation results, revealed that the presence of strong interfacial electric fields promoted superior separation efficiency in the Au-ZnIn2S4/NaTaO3 S-scheme heterojunction. This innovative work may shed light on a more appealing and meaningful approach to modify sodium tantalate for the promising application in photocatalytic hydrogen generation.