Z-scheme heterojunction WO3/BiOBr supported-single Fe atom for ciprofloxacin degradation via visible-light photocatalysis

Single-atom catalysts have drawn tremendous attention on account of their high activity, selectivity and stability. Z-scheme heterojunctions can effectively improve the utilization of optical energy due to the enhanced separation of photogenerated electrons and holes. In this work, several catalysts associated with single-atom Fe (FeSA) loaded on Z-scheme heterojunction WO 3 /BiOBr were prepared; their structure, morphology and photoelectric properties were analyzed; their photocatalytic degradation performance of Ciprofloxacin (CIP) was investigated; and the effects of initial pH, initial CIP concentration, catalyst dosage, light intensity , inorganic anions and humic acid on CIP removal rate were examined. Relevant results showed that the percentage of CIP removal by FeSA/WO 3 /BiOBr could reach 98.5% (120 min); the optimal conditions were pH= 9, [CIP] 0 = 10 mg/L, [FeSA] 0 = 0.8 g/L and I light = 500 W (100% degradation rate within 30 min);·O 2 - and h + were the key active species. Results of the cyclic experiments suggested good stability of the catalyst. Furthermore, the mechanism of CIP photocatalytic degradation was proposed to be a synergistic mechanism of Z-scheme heterojunction migration and valence cycling between single-atom Fe 2+ and Fe 3+ . Finally, the products and pathways of CIP degradation were analyzed.