摘要: Photocatalytic synthesis of hydrogen peroxide (H2O2) from water and oxygen is a promising yet challenging green route, primarily limited by severe charge recombination and the inefficient activation of inert O2 molecules. To address these dual bottlenecks, this work constructs an organic/inorganic step-scheme (S-scheme) heterojunction by intimately coupling C3N4 with Bi2O3. This unique architecture, as deciphered by in-situ XPS and femtosecond transient absorption spectroscopy, drives efficient S-scheme charge transfer. This process not only achieves spatial separation of powerful photogenerated carriers but also retains their high redox potential. Crucially, density functional theory calculations reveal that the interfacial electronic coupling induces a significant electron redistribution, which dramatically enhances the adsorption and activation of O2 molecules—a finding corroborated by oxygen temperature-programmed desorption. Consequently, the optimized C3N4/Bi2O3 photocatalyst delivers a remarkably high H2O2 production rate of 4.03 g-1 h-1 under simulated sunlight. The in-situ generated H2O2 further translates into superior disinfection efficacy, achieving 99.9% inactivation of E. coli within 60 min. This work elucidates the charge dynamics at organic/inorganic S-scheme interfaces and showcases a viable pathway for designing efficient photocatalysts for coupled solar fuel production and environmental applications.