Selective Generation of Co(IV)-Oxo Species in Catalytic Ozonation Process for Effective Decontamination of...

Heterogeneous catalytic ozonation (HCO) is widely used for degrading organic contaminants in wastewater, yet its efficiency is severely compromised in high-salinity environments due to the quenching of hydroxyl radicals (HO^•) by common background anions. Herein, we report the rational evolution from single-atom to diatomic Co catalysts (Co-DAC), which precisely regulate the adsorption configuration of O₃ and switch the dominant reactive oxygen species from nonselective HO^• to highly selective Co(IV)═O species. In contrast to the end-on O₃ adsorption on an isolated single-atom site, the adjacent dual Co atoms favor a bridge-like O₃ adsorption configuration with a more symmetric charge distribution, which facilitates homolytic O-O bond cleavage and thus promotes Co(IV)═O formation. Consequently, the Co-DAC/O₃ system exhibits exceptional resistance to high salinity (100 mM Cl^-) and achieves a record-high mass activity (0.90 mmol g^-1 min^-1) of oxalic acid removal. As a proof of concept, a carbon nanotube-supported Co-DAC membrane is equipped in a flow-through reactor to intensify convective mass transfer, yielding a 162-fold increase in the decontamination rate over a conventional batch configuration. This work not only advances the mechanistic understanding of O₃ activation on diatomic sites but also provides a scalable solution for treating refractory organic pollutants in high-salinity wastewater.