Single-Atom Copper@Carbon Nanospheres for Catalytic Ozonation: Parallel Dual Surface Oxidation Pathways for Broad-Spectrum Water Pollutant Removal

Heterogeneous catalytic ozonation (HCO) is a promising strategy for removing organic pollutants from wastewater, but its practical deployment is limited by the scavenging effects of coexisting constituents (e.g., inorganic anions and humic acids) on hydroxyl radicals (^•OH). Herein, we developed atomically dispersed single-atom copper@carbon nanospheres (Cu-NC-3), which effectively decompose ozone (O₃) to generate surface atomic oxygen (*O), as confirmed by the in situ Raman experiments and theoretical calculations. The *O species rapidly degrade 60% of oxalic acid (OA) within 1 min, while protonation of *O produces surface-confined hydroxyl radicals (^•OH_ad) that achieve 94.7% removal of benzoic acid (BA) and other aromatic compounds. Compared to ozonation alone, the O₃/Cu-NC-3 system enhances OA and BA removal by 34.5- and 1.5-fold, respectively. Atomic-level Cu dispersion induces carbon defects that enrich surface O₃, and Cu-N₄ coordination sites promote its conversion to *O and ^•OH_ad. This dual-oxidation mechanism effectively ensures and enables broad-spectrum pollutant removal and exceptional catalytic stability under long-term operation. Therefore, the O₃/Cu-NC-3 system offers a robust and efficient approach for treating real wastewater containing diverse interfering species.