Source  Chemical Engineering Journal 

Published  Sep 2026 

DOI:  10.1016/j.cej.2026.182316 

IF 12.5

Abstract  Regulating the oxidation selectivity of heterogeneous high-valent Co(IV) = O remains a major challenge in non-radical Fenton-like catalysis. Here, we demonstrate that coordination engineering of Co–N_x single-atom catalysts (CoN_x/CN) provides an effective strategy to tune the formation and reactivity of Co(IV) = O. The optimized CoN₂/CN–peroxymonosulfate (PMS) system markedly enhances Co(IV) = O generation and enables rapid, selective degradation of diverse micropollutants within minutes, while exhibiting strong resistance to pH, anions, natural organic matter, and real-water matrices. A CoN₂/CN-based catalytic membrane further achieves >93.9% nicosulfuron (NIC) removal over 9 d of continuous operation with negligible Co leaching (<0.014 mg l^{−1). In-situ spectroscopy and density functional theory calculations reveal that the unsaturated Co}N₂ coordination promotes interfacial electron transfer and lowers the O—O activation barrier in the adsorbed PMS intermediate, thereby facilitating the coupled generation of Co(IV) = O and ¹O₂. This dual-species pathway enables CoN₂/CN to selectively cleave the pyridine-C–N and oxadiazine-C–O bonds of NIC, driving deeper ring-opening and producing low-toxicity intermediates, whereas CoN₄/CN and CoN₃/CN follow less selective, higher-energy routes. This work establishes a coordination-dependent reactivity framework for Co single-atom catalysts and highlights coordination engineering as a powerful strategy for developing selective, robust, and intrinsically controlled advanced oxidation systems.