Enhanced Photocatalytic CO₂ Reduction with Photothermal Effect by Cooperative Effect of Oxygen Vacancy and Au Cocatalyst

CO₂ conversion into chemical fuels is a sustainable approach to the concurrent mitigation of the energy crisis and the greenhouse effect. It is still urgently desirable but quite challenging to explore a promising catalyst for CO₂ photoreduction due to the severity in the fast recombination of electron holes and the deficiency of active sites, which have a tremendous influence on the catalytic behavior. In this regard, mesoporous TiO₂ nanospheres containing oxygen vacancies (OVs) and metallic Au nanoparticles (NPs) were successfully prepared and showed markedly enhanced CO₂ reduction activity and CH₄ selectivity by the simple combination of photocatalysis with the simultaneous photothermal effect under full-spectrum irradiation. The dual introduction of OVs and a Au/TiO₂ Schottky junction can not only serve as an electron sink to significantly improve the charge separation/transfer efficiency but also show effective photothermal conversion to raise the local temperature of the catalyst, thus resulting in an enhanced shuttle of electrons and desorption of products. This study not only offers new insights into the integrated tuning of charge recombination processes but also demonstrates that the photothermocatalysis has great potential in CO₂ reduction.