Enhancing Built-In Electric Field via Defect-Mediated Interfacial Chemical Bond Construction in Chalcogenide Heterojunction for Alcohol Photooxidation Coupled with H2 Production

Rationally designing nanostructures based on an adequate understanding of structure-performance relationships is key for directional charge transfer regulation in heterojunction photocatalysts. A general strategy is developed for synthesizing bifunctional Sv-chalcogenide/Ti₃C₂ Schottky junctions (Sv = sulfur vacancies, chalcogenides containing CdS, CdIn₂S₄, ZnIn₂S₄, ZnS, CuInS₂) featuring a giant built-in electric field (BIEF) via defect-mediated heterocomponent anchorage, which consists of sulfur vacancy modulation of chalcogenides and Ti₃C₂ nanoparticle anchoring at defects via interfacial Metal─Oxygen (M─O) bonds. These heterojunctions have the distinctive interface structure of semicoherent phase boundaries and a directionally aligned BIEF pointing from chalcogenides to Ti₃C₂. The enhanced BIEF creates an asymmetrical charge distribution, which not only governs the charge migration behavior by enabling charge carrier localization and delocalized electron transport continuity but also regulates the molecular catalytic behavior by optimizing pivotal intermediate adsorption/activation (^*Ar-CH(R₂)-OH in dehydrogenation and H^* in H₂ evolution) in selective alcohol photooxidation coupled with H₂ generation. Encouragingly, Sv-chalcogenide/Ti₃C₂ exhibits unprecedented performance (up to 13.34-fold higher efficiency than unmodulated chalcogenides) and good substrate compatibility for various alcohols. This work demonstrates the synergistic effects of surface electron density control and interfacial interaction modulation in regulating BIEFs, elucidating the substantial impact of reinforced BIEF on carrier transport properties and molecular catalytic behavior.