Calcination engineering of urchin-like CoO -CN catalysts to enhance photothermocatalytic oxidation of toluene via photo-/thermo- coupling effect

Photothermocatalysis is usually the photoinduced thermal effect to drive the catalytic reaction assisted by high-oxidizing radials from photocatalysis. Herein, a carbon nitride-induced urchin-like catalyst Co3O4-CoO-CN (abbreviated as CoOx-CN) with abundant peripheral branches is synthesized through the solvothermal reaction and calcination at different temperatures. An appropriate calcination temperature can remove partial CN structure and help to promote the light absorption, maintain the high specific surface area, and produce enough active oxygen species and active sites. CoOx-CN-300 exhibits the good catalytic activity with toluene conversion of 83.8% and CO2 yield of 79.6% under the full spectrum irradiation, where photocatalysis plays an important role in igniting catalytic reaction and light-to-thermal conversion provides high temperature to fulfil intermediates mineralization. Furthermore, light irradiation can enhance the light-driven thermocatalytic performance of CoOx-CN-300 compared to conventional thermocatalytic activity by activating more lattice oxygen and inducing the formation of more oxygen vacancies to participate in the oxidation reaction.