Phosphorus-doped CoFe-prussian blue analogues (PBA)-Derived oxide with defect engineering for efficient peroxymonosulfate activation toward SMX degradation.

In this work, phosphorus-doped cobalt ferrite nanocubes (P-FCO) were synthesized from CoFe-PBA precursors via high-temperature oxidation and phosphorus doping. The P-FCO2/PMS system achieved 99 % removal of 20 ppm sulfamethoxazole (SMX) within 10 min, with an apparent rate constant of 1.52 min-1, outperforming most reported Co-Fe catalysts. Phosphorus doping increased oxygen vacancy concentration and enriched low-valence Co2+/Fe2+ species, enhancing PMS chemisorption. The formation of M(Co/Fe)-O-P bonds modulated the electronic structure, reduced electron transfer barriers, and promoted a direct electron transfer pathway mediated by metal-PMS* complexes. PMS activation involved synergistic radical (SO4•-) and non-radical (1O2 and direct electron transfer) pathways, accelerating SMX degradation and mineralization. DFT calculations confirmed that phosphorus doping strengthened PMS adsorption, improved electron migration, and lowered the activation energy. This work integrates defect engineering and electronic modulation via heteroatom doping, establishing a direct electron transfer-dominated mechanism and offering a design strategy for high-performance water treatment catalysts.