Synergistic sulfur vacancies and Schottky junctions boost charge separation for efficient photocatalytic hydrogen...

Efficient solar-driven hydrogen evolution remains limited by inefficient charge separation and rapid carrier recombination in semiconductor photocatalysts. Here we report a sulfur-vacancy-rich ZnIn₂S₄/NiCo₂S₄ Schottky heterojunction photocatalyst that integrates defect engineering with interfacial electronic regulation to enhance photocatalytic hydrogen production. Comprehensive structural and spectroscopic characterizations confirm the introduction of abundant sulfur vacancies in ZnIn₂S₄ and the formation of an intimate Schottky interface with metallic NiCo₂S₄. The optimized composite exhibits a hydrogen evolution rate of 16.21 mmol g^-1 h^-1 under simulated solar irradiation, representing a 10.32-fold enhancement over pristine ZnIn₂S₄, together with excellent photostability. Mechanistic studies supported by photophysical analyses and density functional theory calculations reveal that sulfur vacancies serve as electron-trapping sites to promote proton reduction, while the Schottky junction establishes a built-in electric field that drives directional electron transfer and suppresses charge recombination. The synergistic coupling of defect-mediated electron accumulation and interfacial barrier modulation substantially prolongs carrier lifetime and maximizes charge utilization. This work demonstrates an effective defect-interface engineering strategy for constructing high-performance photocatalysts for solar hydrogen production.