Unlocking Electro-Enhanced Peroxymonosulfate Activation Mechanism with a Single-Atom Cobalt Monolithic Electrode toward Efficient and Sustainable Water Decontamination

Electrochemical advanced oxidation processes (EAOPs) show great potential to scale across centralized and distributed treatment contexts and thus already have detailed mechanism studies and practical applications, such as the electro-oxidation and electro-Fenton techniques. However, peroxymonosulfate-based EAOPs (PMS-EAOPs), as an emerging electrochemical system in wastewater treatment, still lack the corresponding mechanisms research, particularly in terms of the deep understanding of electro-enhanced PMS activation. Herein, to establish an ideal platform for performance enhancement and mechanistic investigation of electrochemical PMS activation, we developed a self-supported single-atom cobalt electrode that couples catalytic active sites with excellent mass transfer to fully unleash its intrinsic activity. It is found that the anode electric field can create a PMS-enriched interface microenvironment, delivering a 26.6-fold activity enhancement relative to the cathodic counterpart. Meanwhile, electric field-induced electron delocalization at the cobalt site facilitates electron transfer with PMS. This dual synergistic modulation collectively lowers the physical and energetic barriers for PMS activation, achieving 100% sulfamethoxazole removal within 2 min while reducing oxidant dosage by 80-90% relative to other reported PMS-EAOP systems. This study establishes a mechanistic framework for electric field-modulated Fenton-like catalysis, highlighting the critical roles of interfacial microenvironment and electronic structure, and advances the design of PMS-based EAOPs and related electrocatalytic applications.