S-scheme heterojunction construction of Fe/BiOCl/BiVO4 for enhanced photocatalytic degradation of ciprofloxacin

With the growing problem of water pollution caused by antibiotics, the development of photocatalysts with high photogenerated carrier separation efficiency is crucial. A high-efficiency microsphere Fe/BiOCl/BiVO4 with S-scheme heterojunction was synthesized by solvothermal method and its ciprofloxacin (CIP) degradation performance were investigated under visible light. XRD, FT-IR, SEM, EDS, HRTEM and XPS results show that the photocatalytic have good crystallization, morphology and the formed a microsphere. The photocatalytic performance of Fe/BiOCl/BiVO4 for CIP was superior to pure BiOCl and BiVO4 due to the microsphere and formed heterostructure between BiOCl and BiVO4. The influencing factors of CIP degradation by Fe/BiOCl/BiVO4 were investigated, and the results showed that Fe/BiOCl/BiVO4 had high degradation efficiency not only at pH 5–9, but also in the presence of inorganic Cl−, NO3− and metal ions. Under the optimal conditions, the degradation rate of CIP was up to 100% in 75 ​min. In addition to CIP, the Fe/BiOCl/BiVO4 photocatalysts degraded other organic pollutants, such as tetracycline, oxytetracycline, chlortetracycline, ofloxacin, levofloxacin, and rhodamine B, by more than 92%. The main active species were photogenerated holes (h+) and superoxide radicals (·O2−). In addition, possible intermediates and toxicity of intermediates were analyzed and five potential pathways for CIP degradation were proposed.