Dual-vacancy enhanced built-in electric field boosting plasmonic S-scheme photocatalysis for superior hydrogen evolution

Innovative S-scheme heterostructures face intrinsic limitations in charge separation due to insufficient interfacial driving forces. This work pioneers a dual-vacancy engineering strategy to break this bottleneck, constructing a plasmonic ZnIn2S4−x/MoO3−x (ZIS/MO) S-scheme heterojunction where oxygen and sulfur vacancies synergistically reconfigure charge transfer dynamics via dual-path modulation. Uniquely, sulfur vacancies amplify the built-in electric field (IEF) intensity by enlarging the Fermi level gap, while oxygen and sulfur dual-vacancies induce localized surface plasmon resonance (LSPR) via free-carrier concentration enhancement. Simultaneously, sulfur vacancies lower the H* adsorption barrier, and dual vacancies amplify photothermal conversion by promoting nonradiative decay, accelerating temperature elevation and kinetics. Electron dynamics confirm that this dual-vacancy synergy prolongs charge carrier lifetime by a factor of 5.23. Consequently, the optimized sulfur vacancy-rich ZnIn2S4−x/MoO3−x (R-ZIS/MO) exhibits remarkable photocatalytic hydrogen production rates of 3.60 mmol g−1 h−1 under visible light and 22.74 mmol g−1 h−1 under full-spectrum irradiation, representing 7.8-fold and 17.2-fold enhancements, respectively. This study establishes a new paradigm. Targeted dual-vacancy coordination in plasmonic heterostructures enables unprecedented IEF-LSPR co-modulation, opening avenues for high-efficiency solar energy conversion.