Photo-induced carbon dioxide reduction on hexagonal tungsten oxide via an oxygen vacancies-involved process

Although converting the greenhouse gasses carbon dioxide (CO₂) into solar fuels is regarded as a convenient means of solar energy storage, the intrinsic mechanism on how the high chemical inertness linear CO₂ molecules is activated and converted on a semiconductor oxide is still elusive. Herein, by creating the oxygen vacancies on the typical hexagonal tungsten oxide (WO₃), we realize the continuous photo-induced CO₂ reduction to selectively produce CO under light irradiation, which was verified by isotope labeling experiment. Detailed oxygen vacancies evolution investigation indicates that light irradiation can simultaneously induce the in-situ formation of oxygen vacancies on hexagonal WO₃, and the oxygen vacancies promote the adsorption and activation of CO₂ molecules, leading to the CO₂ reduction to CO on the hexagonal WO₃ via an oxygen vacancies-involved process. Besides, the existence of water further promotes the formation of CO₂ reduction intermediate, further promote the CO₂ photoreduction. Our work provides insight on the mechanism for converting CO₂ into CO under light irradiation.