Enhanced Photocatalytic Oxidation of Ofloxacin by Fe-Doped BiOCl: Role of Fe in Carrier Trapping, Band Gap Narrowing, and DFT-Calculated OFL's reaction sites

In this work, the co-precipitation method was used to prepare Fe-doped BiOCl-modified materials for visible photocatalytic degradation of ofloxacin in water by taking advantage of the property that the acidic nature of FeCl 3 ·6H 2 O dissolved in water can improve the surface structure of the materials. In order to improve the problems of BiOCl’s poor absorption of visible light and high compounding rate of electron-hole pairs, the transition atom Fe is introduced to add impurity energy levels in BiOCl, which effectively reduces the bandgap width of the material and promotes the photogenerated electron migration of the material, and it is calculated that after modification, the band gap of the material can be reduced to 2.79   eV, which is a decrease of 0.32   eV compared to the original BiOCl (3.11   eV). Fe acts as an electron trap to capture electrons in electron-hole pairs and slows down their complexation with holes, effectively enhancing the stability of carrier separation in the material. Through free radical quenching experiments and ESR assays, it is understood that superoxide radicals are one of the free radicals needed in that act in the reaction process, indicating that the efficient electron capture enables the electrons to better react with adsorbed oxygen to generate superoxide radicals, which enhances the oxidizing ability of the system. Meanwhile, the degradation ability of modified materials on ofloxacin has been studied. Compared to the original BiOCl, under the condition of adding 50   mg/100   mL, the degradation ability of modified materials on ofloxacin has significantly improved. After 100   min of light exposure, the degradation efficiency of OFL·(10   mg/L) increased from 26.10% to 88.02%.