Remarkable photoconversion of carbon dioxide into methane using Bi-doped TiO2 nanoparticles prepared by a conventional sol–gel method

Abstract Bi ions were inserted into a TiO 2 framework in order improve the CO 2 reduction. The x-mol% Bi ion-incorporated TiO 2 s were prepared by a conventional sol–gel method, and characterized by XRD, TEM, UV–visible spectroscopy, photocurrent spectroscopy, and CO 2 -TPD. The adsorption of CO 2 was significantly increased on Bi–TiO 2 s, which demonstrated superior photocatalytic behavior compared to that of pure TiO 2 . The 5.0 mol% Bi–TiO 2 produced 3400 μmol g cat −1  L −1 CH 4 gases after an 8 h reaction. The photocatalytic activity was dramatically enhanced by the improved effective CO 2 gas adsorption and by the inhibited recombination of photogenerated electron–hole pairs due to the enhanced charge separation.