Insight into enhanced Fenton-like degradation of antibiotics over CuFeO2 based nanocomposite: To improve the utilization efficiency of OH/O2- via minimizing its migration distance.

In Fenton or Fenton-like processes, the key step is to catalyze H2O2 and produce highly reactive OH radicals. More efforts are then focus on designing efficient heterogeneous Fenton catalysts by activating H2O2 to generate OH at the highest possible steady state concentration. In this study, using the antibiotic ofloxacin as target organic pollutant, we firstly demonstrate a point of view for improving OH utilization efficiency by regulating surface chemical reactions to minimizing its migration distance to the target pollutant. C doped g-C3N4 incorporated CuFeO2 (CCN/CuFeO2) exhibited almost ten times higher ofloxacin degradation rate constant than our previously reported CuFeO2 {012} catalyst (0.1634 vs 0.0179 min-1). Since similar amount of OH was generated, the different inhibition effect of tert-butyl alcohol and nitrobenzene on the ofloxacin degradation confirmed that the much-enhanced ofloxacin degradation was attributed to the surface Fenton reaction process. According to XPS and EXAFS characterization, the C-O-Cu bond between g-C3N4 and CuFeO2 established a closed-circuit surface Fenton reaction mechanism. H2O2 was adsorbed and decomposed into OH/O2- over ≡Cu + site in CuFeO2. The successful construction of CCN/CuFeO2 creates a negative surface potential and benefits the enrichment of target antibiotics from water, which greatly reduces the migration distance of OH/O2•- to adjacent pollutant and then increases the OH/O2- utilization efficiency by avoiding the unwanted quenching. Hence, CCN/CuFeO2 possesses superior Fenton catalytic activity and long-term stability.