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

Abstract

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 Co 3 O 4 /TiO 2 composite via treatment under H 2 and Ar flow at 200°C, and the photothermal catalytic performance of toluene is significantly improved. The molecular oxygen (O 2 ) adsorbed by Vo is activated to form reactive oxygen species for deep oxidation of toluene. Vo generated on the unilateral side in Co 3 O 4 /TiO 2 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. • The oxygen-vacancy-induced O 2 adsorption and activation mechanism in photothermal catalysis is studied • Oxygen-vacancy-trapped electrons inhibit electron-hole pair recombination • Oxygen vacancies promote rapid photothermal oxidation of toluene and intermediates Oxygen vacancies are known to influence the performance of heterogeneous catalysts. Herein, Yang et al. show that oxygen vacancies in Co 3 O 4 /TiO 2 induce the activation of O 2 and migration of electron holes, with light-generated carriers promoting the generation of active radicals to catalyze the oxidation of toluene.