High-pressure TiO2-II polymorph as an active photocatalyst for CO2 to CO conversion

Rutile and anatase titanium oxide phases are widely used for photocatalytic CO2 conversion, and there have been significant attempts to improve their activity by various chemical methods. In this study, we show that the nanocrystalline high-pressure TiO2-II polymorph, synthesized by a high-pressure technique, shows higher photocurrent and better photocatalytic activity for CO2 to CO conversion compared to the anatase phase. The photocatalytic activity of material is further enhanced by thermal annihilation of oxygen vacancies generated in the bulk of TiO2-II during the high-pressure treatment. The high potential of TiO2-II phase for CO2 conversion is discussed based on the light absorbance, band structure, charge carrier mobility and CO2 adsorption.