Surface Nitrogen-Doped Carbon Decoration of Co Catalyst Supported on Mesoporous Carbon to Boost Peroxymonosulfate Activation for Antibiotics Degradation

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