Surface Nitrogen-Doped\nCarbon Decoration of Co Catalyst\nSupported on Mesoporous Carbon to Boost Peroxymonosulfate Activation\nfor Antibiotics Degradation

Abstract

Peroxymonosulfate (PMS)-based advanced oxidation process\nhas been\ndemonstrated as an effective solution to degrade antibiotics present\nin wastewater. Developing robust catalysts is the key to boost PMS\nactivation for reactive species generation. Herein, a surface nitrogen-doped\ncarbon (NC) decoration strategy is proposed to reconstruct Co catalysts\nsupported on mesoporous carbon (MC) for boosting PMS activation to\ndegrade tetracycline hydrochloride (TCH). High-resolution transmission\nelectron microscopy and N₂ sorption isotherm measurements\nconfirmed that some Co nanoparticles supported on MC could migrate\nand get stabilized on the surface of the NC layer during high-temperature\ncarbonization. X-ray photoelectron spectroscopy analysis indicates\nthe formation of various active sites (including Co–N_<i>x</i>, graphitic N, and lattice oxygen) after surface\nNC decoration. These sites facilitate PMS activation and TCH degradation.\nThe Co/MC@NC-900 catalyst (prepared at a carbonization temperature\nof 900 °C) exhibited the highest degradation performance (∼100%\nTCH removal efficiency in 12 min and apparent degradation rate constant\nof >0.25 min^–1), outperforming the control Co/MC\ncatalyst (∼55% TCH removal and degradation rate constant of\n∼0.12 min^–1). Mechanism studies confirmed\nthe coexistence of radical and nonradical degradation pathways in\nthe system under study. Particularly, Co/MC@NC-900 enables SO₄^•–, ^•OH, and ¹O₂ formation\nsimultaneously, thus exhibiting considerably improved TCH degradation\nefficiency. The proposed surface NC decoration strategy could enable\nthe development of robust catalysts toward efficient PMS activation\nfor antibiotic degradation.