Well-dispersed cobalt nanoparticles encapsulated on ZIF-8-derived N-doped porous carbon as an excellent peroxymonosulfate activator for sulfamethoxazole degradation

Abstract

The practical application of carbon materials supported cobalt (Co)-based heterogeneous materials as excellent peroxymonosulfate (PMS) activators has attracted wide attention in recent years because of their low particle self-agglomeration and low Co leaching. Herein, we developed a new synthetic strategy for designing Co nanoparticles (Co NPs)-encapsulated zeolitic imidazolate frameworks-8-derived porous carbon (NC) (denoted as Co-N@NC-x) by calcinating NC with a polydopamine-chelating Co coating. It was demonstrated that NC could effectively prevent Co agglomeration because it provided rich load sites for Co. Raman and X-ray photoelectron spectroscopy results indicated that the addition of Co could increase the surface defects of NC. Co-N@NC-90 (0.1 g/L) efficiently catalyzed PMS to degrade >96.91 % of sulfamethoxazole (SMX, 20 mg/L) within 90 min with an initial pH of 3.65–9.05 based on the synergistic effect between Co NPs and NC. It was demonstrated that Co NPs were the main active sites, and the defects and carbonyl (CO) group active sites also contributed to SMX degradation by catalyzing PMS. Graphitic N was an adsorption site for SMX. A singlet oxygen (1O2)-dominated non-radical mechanism has been proposed. Additionally, Co-N@NC-90 exhibited excellent stability resulting from NC encapsulation. This work provides a novel approach for the application of metal organic framework-derived carbon-supported metal catalysts in wastewater purification.