Support-modulated coordination environments direct divergent PMS activation pathways in Co single-atom catalysts

This study investigated the role of support-driven coordination environments in regulating peroxymonosulfate (PMS) activation by single-atom cobalt catalysts. Atomically dispersed cobalt was anchored on graphene oxide (Co/GO) and silica (Co/SiO 2 ) to compare their catalytic pathways and stability. Both catalysts enabled efficient degradation of sulfamethoxazole (SMX), achieving mineralization efficiencies of 36.4 % for Co/GO and 42.7 % for Co/SiO 2 after 60 min. Co/SiO 2 also showed superior structural stability and reduced cobalt leaching during reaction. Mechanistic studies revealed that Co/GO favored the direct formation of Co(IV)=O species, whereas Co/SiO 2 promoted surface-bound radicals, which is attributed to its higher cobalt coordination number and stronger metal-support interactions. Furthermore, both catalysts were incorporated into polyvinylidene fluoride membranes, which maintained high SMX removal efficiency during 7 days of continuous operation with real municipal wastewater. These findings underscore the crucial role of support effects in tailoring PMS activation and offer insights for designing stable single-atom catalysts for water treatment.