Mechanistic insights into plasmon-mediated charge transfer in Pt@BiOBr/g-C3N4 S-scheme heterojunction for solar-driven water treatment

Designing heterojunction photocatalysts with staggered band structures and optimal interfacial interactions constitutes a feasible strategy to achieve superior photocatalytic performance. Herein, we synthesized a Pt@BiOBr/g-C 3 N 4 S-scheme heterojunction via in-situ construction and photochemical deposition. Notably, Platinum nanoparticles (NPs), precisely deposited via photochemical reduction, extend light absorption into the visible-NIR spectrum through localized surface plasmon resonance (SPR) while acting as electron mediators to suppress recombination. Under simulated solar irradiation, the optimized Pt@BiOBr/g-C 3 N 4 S-scheme heterojunction demonstrates complete degradation of tetracycline hydrochloride (TC-HCl) within 10 min. Additionally, the photocatalyst showed exceptional degradation efficiency for organic dyes including methyl orange (MO) and rhodamine B (RhB). More importantly, the synergistic interplay between internal electric field (IEF) and the SPR of Pt nanoparticles collectively facilitates rapid charge separation while suppressing electron-hole recombination. This study offers a path toward highly effective photocatalysts engineered for practical applications and elucidates the activity enhancement mechanism through Pt incorporation in ternary heterojunction systems.