Nitrogen-Doped\nCarbon Materials for Persulfate Activation\nvia Electron Transfer Pathways

The incorporation of nitrogen into carbon materials is\na strategy\nthat effectively boosts their catalytic potency. Herein, a nitrogen-enriched\ncarbon substance, designated as CN<sub>0.6</sub>, was synthesized\nfrom melamine, serving as a precursor. This substance has been established\nto act as an efficient catalyst devoid of metals for the activation\nof peroxymonosulfate (PMS). At a temperature of 25 °C, a concentration\nof 0.05 g/L CN<sub>0.6</sub> along with 1 mM PMS suffices to achieve\nthe complete degradation of concentrated tetracycline hydrochloride\n(TC) in a short period of 4 min. This enhanced catalytic performance\nis attributed to the optimal level of nitrogen doping, which elevates\nthe pyrrolic nitrogen content and introduces additional defects characterized\nby an <i>I</i><sub>D</sub>/<i>I</i><sub>G</sub> ratio of 1.02. These factors collectively augment the adsorptive\ncapacity for PMS and create a greater number of active sites to facilitate\nits activation. The dominance of a nonradical electron transfer mechanism\nin the CN<sub>0.6</sub>/PMS system has been confirmed through a series\nof analyses, including radical identification, quenching tests, and\nelectrochemical assessments. Employing high-resolution liquid chromatography\ncoupled with tandem mass spectrometry (LC-MS), the investigation identified\nthree potential degradation routes for TC. Furthermore, the intermediates\nproduced are determined to possess reduced toxicity in comparison\nto TC. The findings of this study offer a approach to the synthesis\nof highly efficient nitrogen-doped, metal-free catalysts, presenting\na promising strategy for the degradation of environmental pollutants.