Dynamic long-range electron transfer of single‑atom Mo sustains Co nanoparticles for efficient Fenton-like reaction

A hybrid catalyst coupling Co nanoparticles with neighbouring single-atom Mo on carbon carrier (Co NP Mo SA /NC) was developed to sustain peroxymonosulfate (PMS)-based Fenton-like catalysis. Co NP Mo SA /NC was synthesized by pyrolysis of Co/Mo-encapsulated ZIF-8 and characterized by X-ray absorption fine structure to resolve its coordination and valence states. Quenching, probe, and quantification experiments were used to determine the reactive oxygen species and their contributions, while density functional theory calculations elucidated the PMS activation pathways. The Co NP Mo SA /NC/PMS system degraded 99.5% sulfamethoxazole within 20 min ( k obs = 0.679 min −1 ), and maintained > 95% removal over five cycles and in a continuous-flow reactor. High-valent Co-Oxo species and sulfate radical contributed 59.89% and 35.96% to degradation. The system enhanced pharmaceutical wastewater biodegradability, increasing the ratio of biochemical oxygen demand to chemical oxygen demand from 0.309 to 0.716. Molecular transformation and substrate-explicit model showed that the pre‑oxidation step depleted sulfur‑containing organics and reduced the metabolic burden. Single-atom Mo donated electrons to Co nanoparticles via long-range electronic modulation, stabilizing Co valence states in dynamic activation, shifting the d -band centre toward the Fermi level, and lowering the O-O cleavage barrier. This work provides a long-range electron transfer strategy to overcome the kinetic imbalance and deactivation of Co-based PMS activators for water decontamination.