Tailoring the selective generation of high-valent cobalt-oxo by asymmetrically coordinated single-atom cobalt-activated peracetic acid for efficient water decontamination

Abstract

The novel nonradical Fenton-like oxidation based on high-valent cobalt-oxo [CoIVO] species is a promising candidate for selectively removing emerging organic contaminants (EOCs) in complex water; however, efficient and targeted generation of CoIVO is hampered by the high Co-3d orbital occupancy and high bond dissociation energy of deprotonation. Herein, an O doping strategy to construct asymmetric coordination (CoN3O) in Co single-atom catalyst (Co-SAC) is developed to steer peracetic acid (PAA) activation for selectively generating CoIVO. Theoretical calculations suggest that asymmetric coordination of CoN3O could induce significant electron delocalization around Co centers, thus promote adsorption and peroxy O–O bond cleavage of PAA. The asymmetric electronic structure also exerts an additional local electric field, which favors the cleavage of O–H bond via a proton-coupled electron transfer pathway for subsequent CoIVO generation. Consistent with the theoretical prediction, the established CoN3O/PAA system exhibits admirable Fenton-like activity in degrading various EOCs to low-toxicity intermediates through exclusive generation of CoIVO, greatly reducing potential environmental risks. Our work provides a fundamental understanding of the structure–activity–selectivity relationships at an atomic level and provides a design guide to develop advanced CoIVO-involved Fenton-like catalyst for more extensive applications.