Monoatomic oxygen fueled by oxygen vacancies governs the photothermocatalytic deep oxidation of toluene on Na-doped Co3O4

Abstract

Reported herein is a study of oxygen vacancies (OVs) provoking the complete mineralization of toluene with Na-doped Co3O4 as a photothermal catalyst. Doping Na+ into Co3O4 leads to distortion and charge disequilibrium in the Co3O4 lattice, which generates abundant OVs. OVs work as specific centers to convert the absorbed O2 molecules to the active oxygen species O-. Abundant O- radicals boost the outermost decomposition of toluene. Comparing the optimal Na-doped Co3O4 (3%Na-Co3O4) with the pristine Co3O4, despite almost the same removal efficiency (100%) on them, the 3%Na-Co3O4 significantly outperforms Co3O4 concerning the CO2 yield in the photothermocatalytic oxidation of toluene under full-spectrum light irradiation (425 mW/cm2; equilibrium temperature of 218 °C). A mineralization degree of 89.8% is achieved on 3%Na-Co3O4, which is 7-fold higher than that over Co3O4. The OVs also help render the high sustainability of 3%Na-Co3O4, which maintains its outstanding performance even after 10 successive runs.