Oxygen Vacancy Modulating the ·OH Yield of Bi₄O₅Br₂ for Improving the Photocatalytic Inactivation of...

As an important strategy to modulate electronic structure and carrier behavior, oxygen vacancy (OV) is important for modifying semiconductor materials to removal drug-resistant bacteria. Herein, Bi₄O₅Br₂ with abundant oxygen vacancies (OVs) (Bi₄O₅Br₂-OVs) were prepared by room temperature reduction method using L-ascorbic acid (AA) as a reducing agent. Controlled generation of ·OH radicals from the nanomaterial enabled highly efficient removal of methicillin-resistant Staphylococcus aureus (MRSA). The relationship between AA concentration/time and OV concentration was explored. The effect of OV content on the energy band structure was clarified. The equilibrium concentration of OV that can most substantially enhance the photocatalytic performance was evaluated. Under the optimal conditions with 0.15 M AA and 60 min reaction time, Bi₄O₅Br₂-OVs possessed the most suitable oxygen vacancy concentration. The removal concentration of MRSA reached 10^7.11 CFU⋅mL^-1 within 180 min. In addition, ·OH and h⁺ were explored as the main active species components by ESR experiments. It was also determined by free radical quantification experiments that the concentration of ·OH produced by Bi₄O₅Br₂-OVs was four times more than that by bare Bi₄O₅Br₂. Bi₄O₅Br₂-OVs also showed excellent removal rates for antibiotics and antibiotic resistance genes. Moreover, the photocatalysts presented excellent bactericidal ability in the chicken manure water environment. Besides, it also showed high removal rate of MRSA under real sunlight irradiation. Overall, the introduction of oxygen vacancies by room-temperature reduction improved the photocatalytic performance of Bi₄O₅Br₂, which provided a promising application value for the remediation of drug-resistant bacterial contamination in aqueous environments.