Enhancing photocatalytic norfloxacin degradation: Synergistic engineering of heterojunctions and oxygen vacancies in Fe-based MIL

Constructing cost-efficient and robust Fe-MIL-based photocatalysts for efficiently photodegrading antibiotics is highly appealing, however, their intrinsic defects, particularly unsatisfied visible light harvesting efficiency and rapid recombination of charge carriers, provide significant challenges. Herein, oxygen-vacancy-rich Bi 2 WO 6 -OVs/NH 2 -MIL-88B (Fe) composites were successfully constructed via a two-step approach consisting of a hydrothermal reaction followed by NaBH 4 treatment. The chemical compositions, microstructure, morphology, as well as optical properties of the as-prepared samples were thoroughly established. The optimized Bi 2 WO 6 -OV(40)/NH 2 -MIL-88B(Fe) photocatalyst exhibited the maximum photocatalytic efficiency (95.3 %) for the photodegradation of Norfloxacin (NOR), which was considerably greater than that of the heterostructure (56.9 %). The enhancement of photocatalytic performance can be attributed to the collaborative effect between oxygen vacancies and hybrid heterojunctions, which jointly enhances photoexcited electron generation and accelerates charge transfer. Furthermore, from the perspective of practical applications, the effects of pH, NOR concentration, and photocatalyst reuse were carefully investigated. The radical trapping experiments and ESR results verified that superoxide radicals (•O 2 − ), holes (h + ), and hydroxyl radicals (•OH) were the main active species in the NOR degradation process, and the possible photocatalytic mechanism was speculated accordingly. This research provides a promising approach to fabricating Fe-MOF-based heterojunctions with surface oxygen vacancy defect modification for the photodegradation of antibiotics.