FeCN/MXene as novel heterogeneous electro-Fenton catalysts for the degradation of sulfathiazole: Performance and mechanism investigation

Abstract

The present study aims to fabricate heterogeneous electro-Fenton (HEF) cathode catalysts for the in-situ generation of H₂O₂ and the degradation of organic pollutants in water. To achieve this, preparation of Fe and N co-doped MXene composites (FeCN/MXene-x, where x represents the loading content of FeCN) and construction of the HEF system for the degradation of sulfathiazole (STZ) were carried out. The characterization results showed that Fe, C and N mainly existed in the form of Fe₃C and Fe₃N in the FeCN/MXene catalysts, which were favorable for promoting the ORR reaction in the HEF system. Among them, FeCN/MXene-2 exhibited the highest redox electron transfer rate and H₂O₂ selectivity (86%). The catalytic oxidation mechanism of the FeCN/MXene-2/HEF system was investigated by free radical quenching, electron paramagnetic resonance and frontier orbital theory studies. These studies demonstrated that the main active substances for the degradation of STZ were ·OH and ¹O₂. In addition, the excellent stability and practical performance of the prepared cathodic catalysts were demonstrated by cycling experiments and real water sample tests.