Covalent interface engineering regulation of Sillen-Auivillius perovskite for boosting antibiotic photodegradation

Compromised interfacial charge delocalization and inefficient interlayer electron coupling fundamentally constrain the performance of heterojunctions. Herein, a chemically bonded Fe₂O₃/Bi₄TaO₈Br (FEBTB) S-scheme heterojunction with a strong internal electric field was successfully fabricated via an in-situ growth process. Synergistic experimental-theoretical results reveal that the in-built electric field provides a directional driving force for migrating photogenerated carriers between Bi₄TaO₈Br (BTB) and Fe₂O₃. The interfacial Fe-O covalent bridges synergistically act as an atomic-level channel for charge transport while substantially reducing charge transfer barriers, thereby accelerating S-scheme charge transfer and reaching the effective separation of space charges. Impressively, the optimized FEBTB S-scheme heterojunction manifests a significantly improved photocatalytic degradation efficiency of ofloxacin, which is 2.46 and 1.64 times higher than those of BTB and Fe₂O₃. It is worth mentioning that the FEBTB heterojunction maintained 90 % of the OFX degradation within 10 consecutive hours of operation. This study provides atomic-level insight into the interfacial charge transfer mechanism for the efficient degradation of antibiotics in aqueous environments.