Robust degradation of tetracycline via peroxymonosulfate activation over peanut-like Co4N/NC composite: Spatial confinement and heterojunction effects.

Transition metal nitrides have demonstrated potential as activators for peroxymonosulfate (PMS) in the degradation of contaminants because of their intrinsic properties. However, there is a pressing need to develop effective strategies to enhance catalyst stability and reusability across consecutive cycles. Herein, a peanut-shaped nitrogen-doped carbon framework-encapsulated cobalt nitride material (Co 4 N/NC) was successfully synthesized by directly pyrolyzing commercial ethylenediaminetetraacetic acid disodium cobalt salt in air, followed by a nitridation process. The peanut-like Co 4 N/NC structure, which features encapsulated Co 4 N functional centers and heterojunction interfaces between Co 4 N and NC, were advantageous for enhancing active centers and facilitating electron transfer, resulting in improved efficiency in degrading tetracycline hydrochloride (TCH). The Co 4 N/NC-500/PMS system exhibited an impressive TCH removal rate of 95.48 % within 20 min. Furthermore, the Co 4 N/NC-500/PMS system maintained consistent activity across varying solution pH values, in the presence of different anions and organic matter, and demonstrated high degradation efficiency after five cycles. Quenching experiments and electron paramagnetic resonance tests validated the presence of radicals, non-radicals, and direct electron transfer pathways for TCH degradation. Additionally, the degradation intermediates and pathways were elucidated, along with an assessment of the toxicity of these intermediate products. This study provides an efficient and simple strategy that leverages spatial confinement and heterojunction effects to enhance pollutant degradation through PMS activation. [ABSTRACT FROM AUTHOR]