In-situ construction of CdS@ZIS Z-scheme heterojunction with core-shell structure: Defect engineering, enhance photocatalytic hydrogen evolution and inhibit photo-corrosion

Designing the core-shell structure and controlling defect engineering are desirable for improving the performance and stability of semiconductor photocatalysts. Herein, CdS nanorods covered with ultra-thin ZnIn₂S₄ nanosheets, named as CdS@ZnIn₂S₄-S_V (CdS@ZIS-S_V), was synthesized through the strategy of constructing core-shell structure and regulating vacancies. The core-shell structure can confine Cd²⁺ and S²⁻ locally around CdS instead of rapidly diffusing into the solution, thereby inhibiting photo-corrosion. The abundant S vacancies can capture photogenerated electrons and promote the separation of electron-hole pairs, thereby preventing the oxidation of S²⁻ by the holes. In addition, Z-Scheme heterojunction structure helps the effective separation of electron-hole pairs. Notably, the hydrogen production rate of CdS@ZIS-S_V reached 18.06 mmol g⁻¹ h⁻¹, which was 16.9 and 19.6 times than pristine CdS (1.16 mmol g⁻¹ h⁻¹) and ZIS (0.92 mmol g⁻¹ h⁻¹), respectively. Photoelectric Characterization (PEC), Scanning Kelvin Probe (SKP), UV–vis diffuse reflectance spectra (UV–Vis DRS), Finite-Difference Time-Domain (FDTD) explain the electron transfer mechanism and the reason for the enhanced photocatalytic activity. This work has guiding significance for the preparation of photo-catalysts with high activity and inhibiting photo-corrosion by adjusting S vacancies.