Fe doped CeO2 nanosheets as Fenton-like heterogeneous catalysts for degradation of salicylic acid

Fe doped CeO2 nanosheets with various Fe/Ce ratios were synthesized by solvothermal method (ST) and catalytic performances were evaluated by the degradation of salicylic acid (SA) in the presence of H2O2 (Fenton-like oxidation). The Fe-CeO2 mixed oxides were characterized by SEM, TEM, XRD, EPR, Raman, H-2-TPR and XPS, which indicated that 2% Fe doped CeO2 nanosheets (2Fe-CeO2) showed the largest concentration of surface oxygen vacancies and the highest catalytic activity under the optimum reaction conditions due to the complex adsorption of SA and H2O2 on the surface Ce3+. DMPO spin trapping EPR studies and analysis of intermediate products by LC-MS indicated that superoxide species (O-2(center dot-)/HOO center dot) played a crucial role in the oxidation degradation process, meanwhile, the probable pathway of SA degradation was proposed. The strong adsorption of not-fully degraded low molecular weight organic acids (LMWOAs) on the active sites decreased the reusability of 2Fe-CeO2 catalyst, however, the catalytic activities could be recovered by a simple calcination treatment in air atmosphere.