Interfacial engineering induced robust S-scheme heterojunction in Bi₂Sn₂O₇/BiOBr for highly efficient...

This study develops an S-scheme Bi₂Sn₂O₇/BiOBr (BBSO) heterojunction via solid-phase grinding and photo-etching to achieve efficient gas-solid photocatalytic CO₂ reduction (PCR) for enhanced carbon resource cycling. The synthesis process fosters strong interfacial interactions by establishing chemical bonds between BiOBr (BOB) and Bi₂Sn₂O₇ (BSO), resulting in a significant 39.3-fold intensification of the built-in electric field (IEF), thereby facilitating charge carrier transport and improving surface charge separation. Under simulated sunlight, BBSO-0.75 demonstrates a CO production rate of 157.9 μmol·g^-1·h^-1 with 98.4 % selectivity, outperforming pristine BOB and BSO by 14- and 22-fold, respectively, and surpassing most reported sacrificial agent-free BSO/BOB-based systems. Synchronous O₂ evolution combined with ¹³CO₂ isotopic tracing verifies artificial photosynthesis achievement while confirming CO₂ as the exclusive carbon source. Comprehensive in situ characterizations and photoelectrochemical analyses attribute the enhanced performance to defect-engineered interfacial chemical bonding that stabilizes charge-transfer channels and accelerates carrier separation/migration. This work employed defect-anchoring interfacial engineering to construct stable hetero-bonds, establishing a fundamental strategy for designing high-IEF heterojunctions to advance PCR efficiency.