A Review on Photocatalytic Conversion of CO2 Over Modified TiO2 Photocatalysts

The process of photocatalytic reduction of carbon dioxide converts clean solar energy to value-added materials, while reduces the carbon dioxide greenhouse gas. TiO2 is the most widely used semiconductor in this process. However, its large bandgap energy and high rate of electron-hole pair recombination needs to be modified. In this review article, ways to modify TiO2, such as combining with semiconductors and doping metallic and non-metallic elements, as well as the structural features and performance of modified TiO2 photocatalysts with a special focus on charge transfer behavior have been investigated. Various types of photoreactors, including fixed bed, membrane, slurry, etc., have been investigated. Doping with metal and non-metal increases the yield of the product up to 207 times. TiO2 modified by doping with precious metals have high performance. Doping cheaper materials such as g-C3N4 can be employed to achieve similar performance. Moreover, the efficiency of monolith reactors is 23 and 14 times higher than slurry and fixed bed reactors, respectively.