Photocatalytic reduction of CO2 over Sm-doped TiO2 nanoparticles

Abstract Highly efficient photocatalytic reduction of CO2 is essential for solving the greenhouse effect and energy crisis. In this paper, the Sm-TiO2 nanocomposites were successfully prepared via sol-gel method. The CO2 photoreduction activities of synthesized samples were tested under irradiation for 6 h and the results indicate that the 0.5% Sm-TiO2 catalyst has superior performance and stability. The CO and CH4 yields of 0.5% Sm-TiO2 catalyst are 55.47 and 3.82 μmol/g·cat respectively, which are 5.02 and 2.67 times the yield of TiO2. The possible mechanism of Sm doped TiO2 was investigated through comprehensive characterization and photoelectrochemical analysis. After the Sm doping, the photo-generated electrons in TiO2 could migrate to Sm 4f, and some of them can be captured by reducing Sm3+ to Sm2+, which can lower the recombination rate of electron and hole pairs. Therefore, the enhanced photocatalytic performance could be ascribed to large specific surface area, fast separation rate of electron–hole pairs and high visible light response. This report provides some meaningful attempts in researching the CO2 photocatalytic reduction.