CeO2/CuO/TiO2heterojunction photocatalysts for conversion of CO2to ethanol.

An attempt to reduce CO2emissions has led to the development of CeO2/CuO/TiO2heterojunction photocatalysts for photoconversion of CO2to useful products, e.g. ethanol. Composite photocatalysts were simply prepared by mixing TiO2(P25) with different mass ratios of CeO2(1 wt%) and CuO (2 or 3 wt%) by ball milling. The prepared photocatalysts had uniformly distributed CeO2and CuO phases, throughout the TiO2phase. The integration of CeO2and CuO into TiO2at 1 wt% CeO2and 3 wt% CuO produced a composite, with a reduced band gap of 2.88 eV, allowing absorption of lower energy light and a lower electron-hole recombination rate. The 1%CeO2/3%CuO/TiO2photocatalysts yielded ethanol at 30.5μmol gcat-1h-1, almost three times higher than the yield from pure TiO2. This improved CO2conversion efficiency was due to contributions from properties of both additives: CeO2increased light absorption, while CuO acted as an electron trap and enhanced CO2adsorption. In addition, the heterojunction at the interfaces facilitated the photogenerated charge separation, which, in turn, increased the charge participation in the catalyzed conversion reactions.