Oxygen-vacancy-induced O2 activation and electron-hole migration enhance photothermal catalytic toluene oxidation

The rapid elimination of volatile organic compounds and the intermediate analysis with efficient photothermal catalysis are of great significance to the environment. Oxygen vacancies (Vo) play a crucial role in structural modification and performance improvement of heterogeneous catalysts. Accordingly, here, abundant Vo sites are introduced into Co3O4/TiO2 composite via treatment under H2 and Ar flow at 200°C, and the photothermal catalytic performance of toluene is significantly improved. The molecular oxygen (O2) adsorbed by Vo is activated to form reactive oxygen species for deep oxidation of toluene. Vo generated on the unilateral side in Co3O4/TiO2 heterojunctions serves to capture electrons and break the dynamic balance of electron-hole pairs. The excited electrons are trapped by Vo, and the direct recombination of electron-hole pairs is inhibited, thus promoting the photochemical process. Moreover, the photothermal synergy effect and the relationship between Vo evolution and intermediates transformation mechanism are systematically studied.