Effect of La as Promoter in the Photoreduction of CO 2 Over TiO 2 Catalysts

摘要

AbstractIn this work, TiO2has been modified by treating it thermally together with different proportions (0.5–15 wt%) of La2O3. The resulting materials have been extensively characterized by XRD, TEM, N2adsorption isotherms, temperature-programmed CO2desorption, Raman, UV–Vis photoluminescence and X-ray photoelectron spectroscopies. The activity tests of these materials for the gas-phase photocatalytic reduction of carbon dioxide show that the main products of the reaction are in all cases CO and CH4, together with H2from the parallel reduction of water. After the preparation procedure, La phases are best described as oxycarbonates, and lead to improved activity with respect to TiO2with La contents up to 5?wt%. Higher loadings do not, however, lead to further enhanced activity. Retarded electron–hole recombination and enhanced CO2adsorption are invoked as the key factors contributing to this activity improvement, which is optimized in the case of 0.5?wt% La leading to higher productions of CO and CH4and increased quantum efficiency with respect to titania.]]>