Improving the photo‐reduction of CO2 to fuels with catalysts synthesized under high pressure: Cu/TiO2

BACKGROUND In previous studies the enhanced activity of TiO2‐based catalysts synthesized in supercritical medium for photocatalytic reduction of CO2 was proved. RESULTS In this study, Cu/TiO2 photocatalysts were synthesized by hydrothermal methods in supercritical CO2. Two titanium precursors [titanium tetraisopropoxide and diisopropoxititanium bis(acetylacetonate)], two alcohols (ethanol and isopropyl alcohol), and one metal precursor (Cu (II) acetylacetonate) were used in the synthesis. Catalysts produced showed improved properties in comparison with the commercial reference catalyst (Degussa P‐25, Evonik). CONCLUSIONS Specifically, it has been found that Cu/TiO2 catalysts may yield methane production rates 20 times larger than that of commercial TiO2 catalyst without diminishing CO production rate (about 5 times higher than that of commercial catalyst). This result has been mainly imputed to both the formation of oxygen vacancies during the synthesis in supercritical medium and the high capacity of copper to adsorb and activate CO2 molecules, while preventing CO molecules from reoxidation, and avoiding the competitive reaction of hydrogen formation.