Change of band-gap position of MTiO2 particle doped with 3d-transition metal and control of product selectivity on carbon dioxide photoreduction

This study attempted to obtain various products from carbon dioxide photoreduction using TiO2 catalysts doped with different transition metals of Mn, Fe, Co, Ni, Cu, and Zn (MTiO2). The band-gaps of MTiO2 catalysts decreased compared to pure TiO2, except for ZnTiO2. The intensities in photoluminescence curves, which can predict the recombination of excited electrons and holes, were weaker in MTiO2 catalysts than that of pure TiO2. The products obtained from carbon dioxide photoreduction were strongly related to the redox potential of carbon dioxide and the locations of band-gaps of MTiO2 catalysts. Methane was predominantly obtained in pure TiO2, FeTiO2, and NiTiO2 catalysts, and methanol and carbon monoxide were selectively produced in the CuTiO2 and ZnTiO2 catalysts, respectively. This result suggests that the desired product from carbon dioxide photoreduction can be selectively synthesized by doping certain metals.