Insight into the Role of Oxygen Vacancies in Metal Oxides for Carbon Dioxide Reduction

Abstract Conversion of carbon dioxide (CO 2 ) to valuable chemicals by renewable electricity offers a sustainable and attractive route for alleviating carbon footprints. Catalysts employed in the thermochemical removal of CO 2 are predominantly various transition metal oxides, where surface oxygen vacancies (OVs) on oxides often alter the chemical environment of the surface, thereby influencing the chemical reaction processes. In this study, the surface structure of common transition metal oxides under the CO 2 reduction reaction conditions is initially investigated by density functional theory calculation and CatMAP. Then, the CO 2 adsorption process and deoxygenation reaction mechanism on these actual surfaces are systematically investigated. The results indicate that OVs effectively reduce the work function of the catalyst surface, enhancing CO 2 adsorption and activation. The vacancies significantly adsorb oxygen atoms, providing enough electrons for the inert molecule. In the deoxygenation reaction, the C─O bond on one end of CO 2 is notably elongated, ultimately breaking to produce CO. This work provides new insights into the design of metal oxide catalysts with a reconstructed surface.