Co/N co-doped carbonaceous polyhedron as efficient peroxymonosulfate activator for degradation of organic pollutants: Role of cobalt

Abstract

• Synthesized a novel Co,N co-doped carbon material with Core-shell MOFs. • Co@N-C-2 showed superb catalytic performance and low cobalt leaching. • Nonradical way including 1 O 2 and electron transfer dominated oxidation process. • Co species regulated the structure and determined the activation mechanism. • Co@N-C-2/PMS system is resistant to the inorganic anions and NOM. In this study, Co/N co-doped polyhedron carbonaceous catalyst (Co@N-C-2) with abundant mesoporous, high graphitization degree and cobalt content was synthesized via the pyrolysis of core–shell MOFs composite (ZIF-8@ZIF-67). The two cobalt species (Co NPs and Co-N x ) coexisted in Co@N-C-2 were unveiled to play different role in PMS activation. Concretely, the Co-N x served as active sites for 1 O 2 evolution pathway, while Co NPs greatly improved the graphitization degree and thus enhanced the electron transfer pathway. Owing to the novel structure, the as-prepared Co@N-C-2 presented superior catalytic performance upon PMS activation for the removal of several organic pollutants in comparison with the catalysts derived from single MOFs (ZIF-8 and ZIF-67) and the transition metal oxides. Moreover, Co@N-C-2 could be recovered by thermal treatment, and the Co@N-C-2/PMS system also showed high resistance to inorganic anions and natural organic matter (NOM). This study reveals the crucial role of cobalt species in regulating the structure of catalyst and determining the PMS activation pathway.