CeO₂/CuO/TiO₂ heterojunction photocatalysts for conversion of CO₂ to ethanol

Abstract

An attempt to reduce CO2 emissions has led to the development of CeO2/CuO/TiO2 heterojunction photocatalysts for photoconversion of CO2 to 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 CeO2 and CuO phases, throughout the TiO2 phase. The integration of CeO2 and CuO into TiO2 at 1 wt% CeO2 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%CeO2/3%CuO/TiO2 photocatalysts yielded ethanol at 30.5 μmol gcat −1 h−1, almost three times higher than the yield from pure TiO2. This improved CO2 conversion efficiency was due to contributions from properties of both additives: CeO2 increased light absorption, while CuO acted as an electron trap and enhanced CO2 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.

Soft template-assisted copper-doped sodium dititanate nanosheet/graphene oxide heterostructure for photoreduction of carbon dioxide to liquid fuels

“…This conrms the disadvantage of normal TiO 2 which can only absorb and be illuminated by UV light. 7,10,15 The energy bandgap of Ti is determined to be 3.18 eV (Fig. 6(a), right), which agrees well with the reported value of 3.2 eV.…”

“…The composite exhibited good photoactivity in reducing CO 2 to ethanol at a production rate of 233 μmol g cat −1 h −1 . P. Seeharaj and her team 7 used CeO 2 /CuO/TiO 2 heterostructure photocatalyst for CO 2 conversion. They obtained ethanol as the only product at a production rate of 30.5 μmol g cat −1 h −1 .…”

“…It is clear that with no assistance from the NaOH, TiO 2 takes the form of nanoparticles with diameter sizes ranging from 3 to 11 nm. 7,24,32 CTN (Fig. 2(d)) appears as a combination of nanosheets and nanoparticles, in which the nanoparticle has an average size of 6.4 AE 1.8 nm and nanosheets provide an average size of 51.7 AE 18.7 Â 60.1 AE 26.5 nm 2 .…”

“…The approach concerns not only the removal of CO 2 but also the generation of commodities, such as methane, 1–3 carbon monoxide, 2,3 formaldehyde, 4 methanol, 4,5 and ethanol. 6,7…”

“…The approach concerns not only the removal of CO 2 but also the generation of commodities, such as methane, 1-3 carbon monoxide, 2,3 formaldehyde, 4 methanol, 4,5 and ethanol. 6,7 Different techniques were introduced and demonstrated for CO 2 conversion, including CO 2 xation and conversion by microalgae, CO 2 hydrogenation by metal oxide catalyst, 8 and CO 2 splitting using a metal oxide electrocatalyst. 9 Photoreduction of CO 2 to liquid fuels is an attractive alternative that relies on photocatalysts such as zinc oxide (ZnO), 3,10 cadmium sulde (CdS), 2 and titanium dioxide (TiO 2 ).…”