CeO 2 /CuO/TiO 2 heterojunction photocatalysts for conversion of CO 2 to ethanol

Abstract An attempt to reduce CO 2 emissions has led to the development of CeO 2 /CuO/TiO 2 heterojunction photocatalysts for photoconversion of CO 2 to useful products, e.g. ethanol. Composite photocatalysts were simply prepared by mixing TiO 2 (P25) with different mass ratios of CeO 2 (1 wt%) and CuO (2 or 3 wt%) by ball milling. The prepared photocatalysts had uniformly distributed CeO 2 and CuO phases, throughout the TiO 2 phase. The integration of CeO 2 and CuO into TiO 2 at 1 wt% CeO 2 and 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%CeO 2 /3%CuO/TiO 2 photocatalysts yielded ethanol at 30.5 μ mol g cat −1 h −1 , almost three times higher than the yield from pure TiO 2 . This improved CO 2 conversion efficiency was due to contributions from properties of both additives: CeO 2 increased light absorption, while CuO acted as an electron trap and enhanced CO 2 adsorption. In addition, the heterojunction at the interfaces facilitated the photogenerated charge separation, which, in turn, increased the charge participation in the catalyzed conversion reactions.