Fabrication of nitrogen-doped MXene composite electrode for efficient removal of sulfadiazine in homogeneous electro-Fenton system

In this study, N-MXene-x (x denotes N loading) nanocomposites were successfully prepared by thermostatic ultrasonication and used as a cathode to construct a homogeneous electro-Fenton (EF) system for the degradation of sulphadiazine (SDZ). The characterization results that the electrocatalytic activity of the N-doped composites is significantly increased, which facilitates the two-electron oxygen reduction reaction (2e--ORR) and thus promotes the generation of hydrogen peroxide (H2O2) in the system. Experimental findings demonstrate that the N-MXene-3 cathode exhibits exceptional degradation performance for SDZ (97% removal in 60 min) during the homogeneous EF process. The catalytic oxidation mechanism of the N-MXene-3/EF system was explored by free radical quenching, electron paramagnetic resonance and frontier orbital theory studies, in which the main active substance for degrading SDZ was •OH. DFT calculations combined with the analysis of LC-MS results showed that SDZ was degraded mainly through amino oxidation, hydroxylation of heterocyclic roots, heterocyclic root ring opening, and C-S bond breaks. In addition, the N-MXene-3 cathode catalyst prepared in this study showed excellent stability through repeated experiments and also showed good performance in real water sample.