Exploration of the mechanism of levofloxacin removal by N-doped-induced interfacial micro-electric field-activated persulfate

The defects formed by N doping always coexist with pyrrole nitrogen (Po) and pyridine nitrogen (Pd), and the synergistic mechanisms of H2O2 production and PMS activation between the different Po: Pd are unknown. This paper synthesized MOF-derived carbon materials with different nitrogen-type ratios as cathode materials in an electro-Fenton system using precursors with different nitrogen-containing functional groups. Several catalysts with different Po: Pd ratios (0:4, 1:3, 2:2, 3:1, 4:0) were prepared, and the best catalyst for LEV degradation was FC-CN (Po: Pd=3:1). X-ray Photoelectron Spectroscopy (XPS) and density-functional theory (DFT) calculations show that the introduction of nitrogen creates an interfacial micro-electric field (IMEF) in the carbon layer and the metal, accelerates the electron transfer from the carbon layer to the Co atoms, and promotes cycling between the Fe3+/Co2+ redox pairs, with the electron transfer reaching a maximum at Po: Pd = 3:1. FC-CN (Po: Pd=3:1) achieved more than 95 % LEV degradation in 90 min at pH = 3–9, with a lower energy consumption of 0.11 kWh m−3 order−1. and the energy consumption of the catalyst for LEV degradation is lower than that of those catalysts reported. In addition, the degradation pathway of LEV was proposed based on UPLC-MS and Fukui function. This study offers some valuable information for the application of MOF derivatives.