Novel photocatalytic activity of Cu@V co-doped TiO2/PU for CO2 reduction with H2O vapor to produce solar fuels under visible light

Article abstract of DOI:10.1016/j.jcat.2016.10.030

In this study, Cu and V co-doped TiO₂ deposited on polyurethane (Cu@V-TiO₂/PU) was synthesized as a catalyst for the reduction of CO₂ with H₂O vapor to preferentially produce CH₄ as a valuable solar fuel under visible light. The Cu and V dopants defected into the TiO₂ lattice, leading to the formation of Ti³⁺ and oxygen vacancies in the lattice. The Ti³⁺ formed in the doped TiO₂ lattice created an intermediate band between the valence band and the conduction band of TiO₂, leading to an increase in the electron–hole pair separation efficiency of TiO₂. The oxygen vacancies existing on the surface of the photocatalyst could induce new adsorption sites to adsorb CO₂. The generated electrons and holes reacted with the adsorbed CO₂ and with H₂O vapor to produce CO and primarily CH₄. Therefore, the Cu@V-TiO₂/PU photocatalysts successfully utilized visible light as the energy source and H₂O vapor as a reductant to reduce CO₂ to CO and CH₄. The Cu@V-TiO₂/PU photocatalysts also supplied sufficient electrons and holes for the selective reduction of CO₂ to CH₄ rather than CO. The 2Cu@4V-TiO₂/PU photocatalyst, with Cu/TiO₂ and V/TiO₂ ratios of 2 and 4?wt.%, respectively, exhibited the highest photocatalytic activity for CO₂ conversion into solar fuels. The production rates of CH₄ and CO produced from the CO₂ reduction by the 2Cu@4V-TiO₂/PU photocatalyst under visible light were 933 and 588?μmol?g^?1?cat.?h^?1, respectively.