Operando bonding nickel thiolate with CdS as efficient photocatalyst for hydrogen evolution

Employing metallic nanoclusters as cocatalysts for semiconductor-based photocatalysts and understanding their roles in enhancing photocatalytic performance is crucial. Herein, a nickel thiolate with cyclohexanethiol as the ligands (i.e. Ni₄(S-cy)₈, cy = cyclohexyl) was synthesized and developed as the cocatalyst for CdS to promote its photocatalytic activity for hydrogen evolution. With a 5 wt% cluster loading, the obtained samples achieve a hydrogen evolution efficiency of approximately 106 mmol g_cat^-1 h^-1 under visible light irradiation, which is five times higher than that of pure CdS. The enhanced catalytic activity is attributed to the removal of ligands from the nickel clusters during photocatalysis, which allows the nickel clusters to embed themselves onto the CdS surface through Ni-S bond interactions. This process generates nickel species on the CdS surface, facilitating the generation and separation of photoinduced electron-hole pairs and thereby enhancing photocatalytic performance. This work highlights the importance of the dynamic evolution of nanoclusters during catalysis and demonstrates the potential of leveraging catalytically inert species to form highly efficient component for photocatalysis.