Synergy Between Controllable Sulfur Defect and NiS Cocatalyst Enabling Efficient Photoredox Coupling Catalysis

ABSTRACT Semiconductor‐based photoredox coupling of selective oxidation of vanillyl alcohol (VOL) to vanillin (VAL) with H 2 evolution provides a sustainable alternative to conventional industrial VAL synthesis processes, yet its performance is often hindered by rapid charge recombination and insufficient active sites. Herein, we report a facile one‐pot hydrothermal strategy to construct NiS‐decorated Zn 3 In 2 S 6 (ZIS) nanoflowers with controllable sulfur vacancies (V S ) for efficient co‐production of VAL and H 2 . Moderate concentrations of V S regulate the surface electronic structure and act as oxidation active sites to optimize VOL adsorption. Meanwhile, uniformly dispersed NiS cocatalysts serve as efficient electron relays and reduction active sites, accelerating charge migration and promoting H 2 generation. Benefiting from the interfacial synergy between V S and NiS, the optimal 1%NiS‐ZIS‐V S2 catalyst delivers an 18‐fold enhancement in both VAL and H 2 production rates relative to pristine ZIS, together with excellent stability and broad substrate versatility. This work highlights the critical role of defect‐cocatalyst synergy in designing advanced cooperative photoredox catalysts for sustainable chemical synthesis.