Ultrafast Peroxymonosulfate Activation via an Easily Synthesized Cobalt Cluster for Selective Cobalt(IV)═O Generation

In Fenton-like reactions, the elevation of the spin state of transition metals enhances the redox processes of adsorbed peroxides and improves the oxidative performance. This study reports an easily accessible carbon-supported high-spin cobalt cluster, Co-NCs/C, which demonstrates enhanced kinetics through selective high-valent cobalt-oxo species (Co(IV)═O) generation for peroxymonosulfate (PMS)-induced catalytic oxidation. This catalyst achieves rapid degradation of sulfamethoxazole (SMX) within the modified kinetic rate constant (k-value) of 2001.7, surpassing all previously reported Co-based catalysts. Furthermore, combined experimental characterizations and density functional theory calculations demonstrate the stable size distribution of cobalt clusters anchored on carbon supports. Within a broad size distribution (0-6 nm), these clusters consistently retain high-spin configurations and exhibit excellent catalytic performance in SMX degradation. The tailored electronic structure of the high-spin Co sites enhances the adsorption and activation of PMS, thereby accelerating the degradation process. This work provides a practical and cost-effective strategy for designing high-efficiency catalysts for PMS-based advanced oxidation processes.