Hollow double-shell stacked CdS@ZnIn₂S₄ photocatalyst incorporating spatially separated dual cocatalysts for the enhanced photocatalytic hydrogen evolution and hydrogen peroxide production

Semiconductor-based photocatalytic water splitting is a promising technology to convert solar energy into chemical energy. However, the photocatalytic performance is seriously limited by the low photo-generated charge separation efficiency and high interfacial reaction resistance. Here, a hollow double-shell stacked CdS@ZnIn₂S₄ system was firstly constructed. The Pt and Co₃O₄ nanoparticles (NPs) as the hydrogen evolution and the hydrogen peroxide production cocatalysts were loaded on the inner surface and outer surface of CdS@ZnIn₂S₄ to obtain a novel Pt/CdS@ZnIn₂S₄/Co₃O₄ photocatalyst. Compared with the CdS@ZnIn₂S₄ and dual cocatalysts randomly incorporated CdS@ZnIn₂S₄/(Pt+Co₃O₄) sample, this well-designed photocatalyst shows high photocatalytic performance with hydrogen evolution rate and H₂O₂ production rate reached 8.53 mmol g⁻¹ h⁻¹ and 5.26 mmol g⁻¹ h⁻¹, respectively, which are 3.8 and 1.8 times higher than those of CdS@ZnIn₂S₄ sample. The enhanced photocatalytic performance can be attributed to the formation of compact heterojunction structure between the ultrathin double shells, which can promote the separation of electron-hole pairs due to its built-in field effect. Besides, the synergistic effect of spatially separated dual cocatalysts are beneficial to the migration of the photo-generated charges to the opposite direction and the suppression of the reverse reaction. This work would pave a way to design unique structure and high-performanced photocatalyts towards photocatalytic water splitting.