Oxygen Vacancy Mediated Plasmonic Bi₂S₃/W₁₈O₄₉ S-Scheme Heterojunction for Efficient Hydrogen Evolution

Solar-driven hydrogen production requires photocatalysts with broad-spectrum light harvesting and efficient charge separation. Herein, a plasmonic Bi₂S₃/W₁₈O₄₉ S-scheme heterojunction was constructed via a one-pot solvothermal strategy, with W₁₈O₄₉ nanowires grown in situ on Bi₂S₃ nanorods. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy directly revealed oxygen-vacancy-induced lattice distortion in W₁₈O₄₉, providing atomic-scale evidence of defect formation. Oxygen vacancies endow W₁₈O₄₉ with enhanced localized surface plasmon resonance (LSPR) effect, extending near-infrared absorption and improving solar utilization. The optimized heterojunction achieves an apparent quantum yield of 10.1% at 420 nm for photocatalytic H₂ evolution. Ultraviolet photoelectron spectroscopy, Mott-Schottky, and femtosecond transient absorption analyses confirm an efficient S-scheme charge-transfer pathway driven by the interfacial electric field, enabling directional carrier migration while preserving strong redox capability. This work highlights the dual role of oxygen vacancies in plasmonic light harvesting and interfacial charge transfer for efficient solar hydrogen production.