Oxygen vacancy regulation and morphological engineering: Study on the construction and synergistic mechanism of Fe-doped BiOBr/activated carbon composite photocatalysts

A bulk photocatalyst (Fe-BiOBr/AC) was constructed by loading Fe-doped BiOBr onto activated carbon (AC). The synergistic enhancement mechanism of the material structure, photoelectrical properties, and catalytic performance induced by AC introduction was systematically investigated. Characterization results revealed that AC not only served as a high-surface-area support providing nucleation sites for in situ growth of Fe-BiOBr, but also promoted the formation of defect-related sites, including oxygen vacancies, on the composite surface through structural regulation. Meanwhile, Fe doping further modulated the local chemical environment of Fe-free counterpart and contributed to improved charge-transfer behavior. The optimal sample Fe-BiOBr/AC8 demonstrated significantly superior degradation efficiency to that of Fe-BiOBr for both the typical organic dye Crystal Violet (CV) and practical wastewater. This superior performance mainly originated from the enhanced adsorption capacity and defect-related active sites provided by AC loading, while Fe doping further promoted favorable charge-transfer characteristics. Moreover, AC loading facilitated the transformation of the catalyst from a powder state to a macroscopic bulk structure, successfully overcoming the technical challenge of nanocatalysts separation and recycling within suspension systems.