Construction of flower-like Zn2+/BiOBr with enhanced visible photocatalytic activity for the degradation of levofloxacin

In this study, a series of Zn2+/BiOBr composite nanomaterials (xmol% Z-B, x = 0, 1, 3, 5, 10, 15) were prepared by the solvothermal method to improve the photocatalytic performance of BiOBr. The morphology, elemental composition and optical properties of the composites were analysed by XRD, SEM, XPS, DRS and other characterisation methods.The photocatalytic activity of xmol% Z-B under the influence of different conditions (Zn2+ doping, catalyst dosing, solution pH, pollutant concentration) was investigated. The doping position, energy band structure and density of states of Zn-doped BiOBr were calculated by DFT. Finally, the photocatalytic mechanism and catalytic stability of the composite material for the degradation of levofloxacin (LEV) were analysed in depth.The results showed that Zn2+ was successfully doped into BiOBr, the composite had a 3D flower-like structure, and the degradation efficiency of the Zn2+-doped composite was enhanced by 34.76 %. When the initial concentration of LEV was 10 mg/L, adding 50 mg of 10 %Z-B catalytic material had remarkable degradation effect on LEV, and the degradation rate can reach 97 % within 30 min. In addition, the degradation rate of the catalytic material with 10 %Z-B still reached 88.84 % after five cycles, indicating that the prepared catalytic material possesses good stability. Further analysis by radical capture experiments and electron paramagnetic resonance (EPR) revealed that the main reactive species involved in the reaction are ∙OH, h+ and ∙O2–, and suggested a possible catalytic mechanism for Zn2+/BiOBr.