Construction of S-Scheme heterojunction Ni11(HPO3)8(OH)6/CdS photocatalysts with open framework surface for enhanced H2 evolution activity

The emerging S-scheme heterojunction shows a particular superiority in enhancing the efficiency of charge separation in photocatalyst. Herein, a Ni11(HPO3)8(OH)6/CdS heterojunctions (NiPO/CdS) are constructed for the first time by loading open framework structure NiPO on the surface of CdS nanoparticles (CdS NPs). The built-in electric field generated at the interface promotes the directional migration of photogenerated electrons from NiPO to CdS. This S-scheme pathway achieves a strong redox capacity and efficient carrier separation. More importantly, the unique triangular and hexagonal channels of NiPO facilitate the exposure of CdS active sites for proton adsorption, H2 production and escape. The hydrogen evolution rate of NiPO/CdS is 39 mmol g-1 h-1 under visible light irradiation, which is 6.5 times higher than that of pure CdS. The NiPO/CdS heterojunction also exhibits remarkable long-term stability. This study provides a new strategy for the ingenious design of S-scheme photocatalysts with excellent photocatalytic performance.