Enhanced bifunctional visible-light-driven photocatalytic production of H2 and H2O2 enabled by Ag-ZnIn2S4/C-In2O3 S-scheme heterojunction

Multifunctional photocatalysts are recognized as efficient solutions to complex energy and environmental challenges. In this study, we report the rationally-designed bifunctional photocatalysts of Ag-ZnIn₂S₄/C-In₂O₃ (AgZISCIO) with S-scheme heterojunction and defect engineering, for highly efficient production of both hydrogen and hydrogen peroxide production. The heterojunction is established by growing ZnIn₂S₄ (ZIS) nanosheets on MOF-derived C-doped In₂O₃ (CIO) nanorods, which favors the formation of built-in electric field, thus facilitating effective photogenerated charge separation. Moreover, by introducing Ag ions into ZIS lattice via a cation exchange reaction, abundant active sites would be created for inducing defects on the heterojunction surface, thereby enhancing the kinetics of oxidation–reduction processes. Under visible-light irradiation, the resultant AgZISCIO photocatalysts exhibit remarkable hydrogen and hydrogen peroxide production rates of 3.19 mmol·g⁻¹·h⁻¹ and 2.42 mmol·g⁻¹·h⁻¹, respectively, outperforming those of most In₂O₃-based photocatalysts reported recently. It is witnessed that the overall enhanced photocatalytic performance could be mainly attributed to the formed S-scheme heterojunction and defect creation for improved photogenerated charge separation and redox capabilities. This work underscores the importance of dual modulation of heterojunctions and defect engineering as an effective strategy for enhancing photocatalytic performance, providing some valuable insights for developing advanced multifunctional photocatalysts.