Synergistic dual-interface engineering of hierarchical Co3O4/SiO2 nanosheets for boosted photo-ozonation of dichloromethane.

This study leverages the "dual-interface" synergy between graphene oxide (GO) and polysiloxane to directionally assemble Co3O4 along the (111) crystal plane, achieving one-step integration with mesoporous SiO2 to form a hierarchically ordered nanosheet structure. Catalytic performance tests revealed that GO-Co3O4-SiO2 achieved 67.9 % dichloromethane (DCM) removal under combined light-ozone conditions, outperforming light-only and ozone-only conditions by factors of 30.0 and 4.8, respectively, while generating substantially fewer chlorinated byproducts (methyl chloride and trichloromethane) compared with control materials. The nanosheet architecture enhanced photothermal conversion, elevating local reaction temperatures by 51.6 °C and accelerating reaction kinetics. The synergistic effects between surface-enriched Co3+ sites and oxygen vacancies facilitated dual activation: Co3+ directly activated DCM, while oxygen vacancies decomposed ozone into dominant reactive oxygen species (ROS: O• and •O2-), which drove DCM degradation. Surface photovoltage and electron spin resonance analyses confirmed that photogenerated holes mediated ozone-to-ROS conversion, rather than directly activating DCM. The findings of this study provide a "dual-interface" synergy strategy for designing efficient catalysts with high light absorption, a high density of catalytic sites, and a high specific surface area for chlorinated hydrocarbon degradation.