Selective Activation of PMS by a Single-Atom MOF in Confined Space: Hydrogen Bond-Assisted Nonradical Pathway and Continuous Flow Verification

Conventional peroxymonosulfate (PMS) activation often depends on nonselective radicals, limiting efficiency and selectivity. Precise nonradical pathways based on singlet oxygen (¹O₂) or high-valent metal oxo species under mild conditions remain difficult to realize. A single-atom cobalt-organic framework (Co SA-MOF) integrates hydrogen bonding and pollutant-mediated dual electron transfer, enabling highly efficient and selective nonradical PMS activation. Mixed cobalt valence states and N-H ligands establish an internal pathway in which isolated Co(II)/Co(III) sites with N-H ligands act as a redox engine. Density functional theory (DFT) shows that N-H groups lower the energy barriers for Co(IV)-O formation and Co(IV)-O conversion to ¹O₂, rationalizing the observed nonradical selectivity. Pollutants such as sulfadiazine serve as external electron donors in electrochemical tests, regenerating Co(III) and accelerating the Co(II)/Co(III) cycle. Molecular dynamics simulations indicate that confined pores provide PMS near bulk water diffusivity and promote pore enrichment and activation. This dual drive mechanism yields nearly complete sulfadiazine removal within 1 min, with nonradical pathways accounting for 80%, PMS utilization above 95%, and high catalytic stability. In a 10 L continuous-flow reactor, cobalt leaching remains below 2.63 μg/L, and a life cycle assessment (LCA) indicates a smaller environmental footprint than a Co₃O₄/PMS system does, providing design guidance for environmentally relevant nonradical PMS catalysts.