Oxygen-vacancy defect engineering to boost the aerobic oxidation of limonene over Co3O4 nanocubes

The heterogeneous aerobic oxidation of biomass-derived limonene under mild reaction conditions is an attractive target for the synthesis of valuable oxygenates, but qualifying catalyst represents an enormous challenge. Herein, we propose an oxygen-vacancy defect engineering strategy for steering the limonene oxidation catalysis over Co3O4 nanocubes. Comprehensive characterizations demonstrate that the incorporation of oxygen vacancy (Ov) in the Co3O4 structure triggers the redistribution of charge density and the modulation of Co chemical environment with the formation of more coordinated unsaturated Co atoms. Both the experimental findings and density functional theory (DFT) calculations explicitly evidence the boosting role of Ov in facilitating the radical initiation process, thereby substantially driving the generation of active radicals for the subsequent oxidation to proceed more feasibly. This work paves a way to structural microenvironment modulation induced by oxygenvacancy defect engineering strategy towards high-performance limonene oxidation catalysis and beyond.