Strong synergistic effect of Co3O4 encapsulated in nitrogen-doped carbon nanotubes on the nonradical-dominated persulfate activation

Abstract

A novel nanohybrid with nano-Co3O4 encapsulated in N-doped carbon nanotubes (Co3O4@NCNTs) was developed as a persulfate (PS) activation catalyst. Co3O4@NCNTs exhibit excellent PS activation performance for Orange G degradation with almost 100% removal efficiency within 30 min, remarkable superior to commercial nano-Co3O4, carbon nanotubes (CNTs) and concentrated acid-treated Co3O4@NCNTs. Such superior catalytic activity of Co3O4@NCNTs contributes to the strong synergistic effects between N-doped CNTs and encapsulated nano-Co3O4, which is mainly originated from Co–N sites at the heterointerface. The PS activation process by Co3O4@NCNTs is dominated by nonradical pathway involving 1O2 generation and indirect electron transfer. The detailed mechanism for the nonradical-dominated PS activation by Co3O4@NCNTs was proposed. Co3O4@NCNTs also exhibit desirable reusability, good stability and facile separability, demonstrating its feasibility for practical application. The present study provides a new strategy to construct heterostructures for environmental-friendly and efficient PS activation catalysts, and an in-depth understanding of the heterogeneous PS activation mechanism.