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.