Abstract
In Fenton-like reactions,high-valent cobalt-oxo(CoⅣ=O)has attracted increasing interests due to high redox potential,long lifetime,and anti-interference properties,but its generation is hindered by the elec-tron repulsion between the electron rich oxo-and cobalt centers.Here,we demonstrate CoⅣ-O genera-tion from peroxymonosulfate(PMS)activation over cobalt single-atom catalysts(Co-SACs)using in-situ Co K-edge X-ray absorption spectra,and discern that CoⅣ-O generation is dependent on the support work-function(WF)due to the strong electronic metal-support interaction(EMSI).Supports with a high WF value like anatase-TiO2 facilitate the binding of PMS-terminal oxo-ligand to Co sites by extracting Co-d electrons,thus decreasing the generation barrier for the critical intermediate(Co-OOSO2-).The Co atoms anchored on anatase-TiO2(Co-TiO2)exhibited enhanced CoⅣ=O generation and superior activity for sulfamethoxazole(SMX)degradation during PMS activation.The normalized steady-state concentra-tion of CoⅣ=O in Co-TiO2/PMS system was three orders of magnitude higher than that of free radicals,and 1.3-to 11-fold higher than that generated in other Co-SACs/PMS systems.Co-TiO2/PMS sustained effi-cient removal of SMX with minimal Co2*leaching under continuous flow operation,suggesting its attrac-tive water purification potential.Overall,these results underscore the significance of support selection for enhanced generation of high-valent metal-oxo species and efficient PMS activation in supported metal SACs.
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