CO2 photocatalytic reduction: Photocatalyst choice and product selectivity

Carbon dioxide (CO2) emission is one of the most well-known causes of global warming. Conversion of CO2 into useful chemical products is an attractive approach to sequestrating CO2 as stable liquids and solids. Among sequestration methods the photocatalytic reduction of CO2 is promising. CO2 photocatalytic reduction involves radical-chain reactions that form proton and anion radicals from electron (e?-) and proton (h?+) transfer between metal oxide photocatalysts and the reactants. Therefore the product distribution of a particular photocatalytic reduction process is difficult to predict. In general, the CO2 photocatalytic reduction process is controlled by several conditions such as reactor configuration, photocatalyst type and the nature of reducing agents. Here we review the parameters that control the photocatalytic reduction activity of CO2. We lists the different photocatalysts for the reduction. All types of photocatalysts exhibit specific behaviours which lead to different product distribution. Metal and non-metal dopants improve the photoactivity of a photocatalyst. The dopants also modify the product distribution by altering the active species. Finally, we identify key factors ruling the photocatalytic activity of CO2 reduction under UV or visible light irradiation.