Photothermal Synergy over TiO 2 -Co 3 O 4 p-n Heterojunctions with Oxygen Vacancies for Efficient Catalytic Removal of Toluene

Abstract

Photothermal catalysis, which integrates the benefits of photocatalysis and thermal catalysis, offers a promising strategy for the reduction of volatile organic compounds (VOCs). Metal oxide composites utilize their distinct interfacial properties to achieve functional traits essential for photothermal catalysis, including efficient light harvesting, cost-effectiveness, and environmental safety. Herein, we constructed a TiO2-Co3O4 p-n heterojunction with surface oxygen vacancies for the fullspectrum photothermal catalytic degradation of toluene. The TiO2-Co3O4 composite catalyst with a Ti/Co molar ratio of 5 can achieve good photothermal catalytic performances, with a stable toluene removal efficiency of 89.01% in 200 min, at a toluene feed concentration of 300 ppm, gas hourly space velocity of 7200 h -1 , and light intensity of 500 mW•cm -2 . After 4 regeneration cycles, the TiO2-Co3O4 composite catalyst can retain up to 97% of its initial activity, indicating excellent regenerability. Thermal catalysis and radical trapping experiments reveal that this composite catalyst generates some radicals under light irradiation, which is vital pathway for the light-driven photothermal catalytic oxidation removal of toluene.