Preparation and characterization of highly efficient Z-scheme oxygen vacancy-BiOBr/CoFe2O4 heterojunction photocatalyst driven by visible light for antibiotic degradation

In this work, magnetic oxygen vacancy-BiOBr/CoFe2O4 (OV-BiOBr/CoFe2O4) composite with Z-scheme heterojunction was prepared by simple solvothermal method. The physicochemical properties of the prepared samples were characterized. The degradation rate of norfloxacin (NOR) by OV-BiOBr/CoFe2O4 under visible light irradiation can reach 94.61%. In addition, OV-BiOBr/CoFe2O4 composite also exhibits excellent photocatalytic performance for other antibiotics, it can be recovered by external magnetic field and still shows good photocatalytic activity after four consecutive times uses. Characterization and experimental results show that the improved photocatalytic performance of OV-BiOBr/CoFe2O4 can be attributed to the improvement of visible light response range, the increase of active sites and the effective separation of electron hole pairs. The results of free radical capture experiment and electron paramagnetic resonance spectra show that •O2− and h+ are the main active substance in photocatalytic degradation of NOR system. Then, combined with the band structure, a Z-scheme heterojunction electron transfer mechanism is proposed. This work enhances the photocatalytic performance of BiOBr and provides a new idea for antibiotic wastewater treatment.