Ternary heterostructure Cu-ZnIn2S4/WO3/WS2 flower-like microspheres for highly-efficient photocatalytic hydrogen evolution under visible-light irradiation

Abstract

Developing a new composite photocatalyst is the key to achieving efficient photocatalytic decomposition of aquatic hydrogen. In this study, Cu-ZnIn2S4/WO3/WS2 nanostructures were prepared by a two-step hydrothermal method. The unique charge transfer mechanism of Cu-doped and mixed heterojunctions (Z-scheme heterojunctions and Type-I heterojunctions) significantly enhances charge transfer and separation, resulting in excellent photocatalytic hydrogen evolution performance of Cu-ZnIn2S4/WO3/WS2. The hydrogen evolution rate of Cu-ZnIn2S4/WO3/WS2 is 93032.29 µmol·g−1·h−1, 37.82 and 3.33 times that of ZnIn2S4 and Cu-ZnIn2S4, respectively, and the quantum efficiency at 430nm is 37.04 %. It is also superior to Pt-modified Cu-ZnIn2S4 (71654.39 µmol·g−1·h−1) and most reported ZnIn2S4-based photocatalysts. In addition, the density functional theory (DFT) calculation results further show that the absolute value of ΔGH* of the composite photocatalyst is significantly reduced to 0.08 eV, and the adsorption–desorption potential barrier is reduced considerably, indicating that the Cu-ZnIn2S4/WO3/WS2 photocatalytic system is more favorable to H* adsorption. This excellent performance is attributed to the unique transfer mechanism of Cu doping and mixed heterojunctions. This study provides a new idea for photocatalytic hydrogen production and can provide a valuable reference for future research on photocatalytic hydrogen production technology.