Ni(OH)₂ Nanoparticle-Modified Co₉S₈/ZnIn₂S₄ Heterojunction for Boosting Photocatalytic H₂ Production

ZnIn₂S₄ (ZIS) is an N-type direct bandgap semiconductor material with a visible light response, which exhibits excellent photocatalytic water-splitting performance. To enhance ZIS-based photocatalysts, heterojunction construction and cocatalyst loading methods have been explored extensively. In this research, a Co₉S₈/ZnIn₂S₄ (CS/ZIS) heterojunction was successfully synthesized via a solvothermal method, and then Ni(OH)₂ nanoparticles were successfully loaded on CS/ZIS by photodeposition, yielding the Ni(OH)₂/CS/ZIS photocatalyst. Our findings reveal tight coupling of ZIS nanosheets with the CS surface, establishing an effectively constructed heterojunction structure that enhances interface charge transfer and light absorption. The synergistic effect of CS and Ni(OH)₂ significantly boosts the photocatalytic hydrogen production of ZIS composites. The optimum hydrogen production rate of CS/ZIS is 10.06 mmol·h^-1·g^-1 and that of Ni(OH)₂/CS/ZIS reaches 12.92 mmol·h^-1·g^-1, a 11.9-fold increase over pure ZIS, with exceptional light stability. Furthermore, we discuss the photocatalytic reaction mechanism based on the experimental and characterization results. This work presents a novel approach to designing highly efficient photocatalysts using ZnIn₂S₄, aimed at enhancing the conversion of solar energy into chemical energy.