Selective activation of peroxymonosulfate through gating heteronuclear diatomic distance for flexible generation of high-valent cobalt-oxo species or sulfate radicals

Abstract

Heteronuclear diatomic engineering has been widely applied to generate selective or nonselective active species in Fenton-like system for wastewater treatment. However, active species adapted to diverse wastewater were different, and flexible control of active species has remained elusive, often necessitating complex and repetitive atom modifications. Here, we proposed a diatomic distance gating strategy that adjusted the spintronic structure of cobalt site for flexible transformation of high-valent cobalt-oxo and sulfate radical for adapted wastewater treatment. Electron paramagnetic resonance spectra, magnetic susceptibility-temperatur curve and partial density of states revealed electron transfer from dx²−y², dz² and dyz orbitals of high-spin cobalt to peroxymonosulfate for high-valent cobalt-oxo generation at 3.8 nm, and from dz² orbital of medium-spin cobalt to peroxymonosulfate for sulfate radical generation at 2.5 nm. The Fenton-like system with 3.8 nm of diatomic distance preferentially degraded contaminants with low n-octanol/water partition constant and high ionization potential, while Fenton-like system with 2.5 nm of diatomic distance readily degraded contaminants with high Hammett substituent constant and low dissociation constant. This study elucidated the effect of diatomic distance on Fenton-like chemistry and provided a blueprint for the design of intelligent Fenton-like system for treating diverse wastewater treatment scenarios.