MOF-derived carbon membranes for catalytic ozonation: Site-dependent evolution of surface atomic oxygen enables efficient water purification.

Surface atomic oxygen (*O) is increasingly considered a reactive oxygen species in catalytic ozonation. However, its role as a key intermediate in ozone activation remains poorly understood, while the mechanism governing its site-dependent evolution and pathway differentiation remains unclear. Herein, a nanoconfinement-enhanced MOF-derived catalytic membrane with dual reactive centers was developed to enable site-dependent *O evolution and the coexistence of radical and nonradical pathways. ZIF-67 was in situ grown on a stainless steel-cobalt hollow fiber membrane and pyrolyzed to construct Co/NC@SSCoM. The confined membrane structure promotes pollutant enrichment and interfacial mass transfer, while pyrolysis generates Co-Nx sites and oxygen vacancies (Vo) as dual active centers. Mechanistic investigations combining experiments and DFT calculations show that ozone activation forms *O at both sites, whereas its subsequent evolution differs. At Co-Nx sites, *O conversion to •OH is more thermodynamically favorable, whereas at Vo sites, *O tends to be preferentially stabilized. This site-dependent evolution of *O enables the coexistence of radical and nonradical pathways. Consequently, rapid atrazine degradation (k = 0.34 s⁻¹) is achieved, about 1000 times faster than single ozonation, with robust performance in real water matrices. This work provides new insights into reactive oxygen intermediate evolution for rational catalytic membrane design.