Spatially Decoupled Dual-Active Sites Break the Activity–Humidity Trade-Off: Achieving Water-Promoted Ozonation of Dichloromethane

Chlorinated volatile organic compounds (CVOCs) present persistent environmental threats due to their recalcitrance to degradation and role in secondary pollution. Through the heterojunction engineering under dynamic Ostwald ripening, a cobalt–manganese oxide featuring a hollow sea urchin-like architecture was constructed. By directionally anchoring Co onto the Mn surface, the trade-off between catalytic activity and humidity tolerance in the ozone oxidation process was successfully addressed. The catalyst features spatially decoupled active centers, where Mn3+ sites mediate dichloromethane (DCM) oxidative decomposition, while adjacent Co3+ centers drive efficient water activation through proton-coupled electron transfer. This unique architecture enables exceptional performance, achieving 93% DCM conversion at 120 °C with an ultralow O3/DCM ratio of 6, which halves the ozone demand of conventional systems. Remarkably, the presence of 3 vol % H2O enhances DCM conversion to 98% and maintains >95% stability over 10 h. In situ DRIFTS and DFT calculations provide direct evidence that water not only induces favorable surface hydroxylation but also actively participates in the reaction cycle as a key reactant, generating sustained •OH/•O2– radical chains. The hierarchically porous structure further accelerates mass transport, while spatially separated active centers eliminate competitive adsorption. This work establishes a “dual-active center and multiscale transport” paradigm, providing an energy-efficient solution for industrial CVOC elimination under practical humid conditions without requiring gas-drying pretreatment.