Atomic-level steering of charge flow from type-II to S-scheme in In2O3/BiOCl via vacancy–metal pairs for CO2 photoreduction

Photocatalytic CO₂ reduction is a promising route for solar fuel production, yet it is often hampered by inefficient charge separation and compromised redox power in conventional heterojunctions. Here, we report a thermal-mediated strategy that intelligently reconfigures the charge transfer pathway in In 2 O 3 /BiOCl heterojunctions from a conventional Type-II to a S-scheme. This transition is driven by the in situ formation of synergistic dual defects—oxygen vacancies and metallic bismuth—enabled by precise solvothermal control. The oxygen vacancies serve as efficient CO 2 adsorption and activation sites, while metallic Bi functions as effective electron bridges. This defect synergy collectively reconstructs the interfacial electronic structure, as directly evidenced by in situ XPS and EPR and confirmed by DFT calculations, which reveal a reversed band alignment conducive to S-scheme charge flow. The resulting S-scheme In 2 O 3 /BBC-Ov heterojunction (InBBC-4) achieves a superior CO production rate of 96.11 μmol g −1  h −1 with 96.7 % selectivity, substantially outperforming its Type-II counterpart. This work offers profound atomic-level insights and establishes a simple thermal-tuning paradigm for designing high-performance photocatalysts through defect-mediated control of charge pathways.