Facile chemical blowing synthesis of interconnected N-doped carbon nanosheets coupled with Co3O4 nanoparticles as superior peroxymonosulfate activators for p-nitrophenol destruction: Mechanisms and degradation pathways

Peroxymonosulfate (PMS)-based advanced oxidation processes are attractive candidates for removal of recalcitrant pollutants, whereas the insufficiency of simple strategies to fabricate low-cost and efficient PMS activators has interfered with the practical application of such technologies. In this study, we have synthesized three-dimensional interconnected N-doped carbon nanosheet frameworks (NCNF) coupled with uniformly distributed cobalt oxide nanoparticles (NPs) (Co3O4-NCNF) through one-pot polymer-chemical-blowing and subsequent thermal oxidation. The achieved Co3O4-NCNF exhibits a high performance toward p-nitrophenol (PNP) degradation through activating PMS with about 98% removal efficiency and apparent rate constant of 0.137 min−1. The degradation process undergoes both radical (SO4•−, •OH and O2•−) and nonradical (1O2) pathways, where SO4•− and 1O2 paly the dominant roles. The PNP degradation has two pathways including the reduction/oxidation and direct oxidation. The structural interconnectivities with highly opened freeway for mass/electron transfer, abundant active surfaces, and synergistic effect of Co3O4 NPs and NCNF in the Co3O4-NCNF provide rich reactive oxidative species for highly efficient PNP degradation. This study offers a gateway to fabricate reactive PMS activator for removal of emerging organic pollutants.