On the general mechanism of photocatalytic reduction of CO2

This paper is going to make a global view of the reaction mechanism of photocatalytic reduction of CO2. During the past decades, extensive studies have been conducted to identify the photocatalytic products of CO2 conversion and their reaction mechanisms. There is a need to propose a general mechanism pattern covering the results of these original researches. Among many factors affecting the redox reaction pathway, this paper focuses on the effect of reductant type as an important issue on the product diversity and selectivity of CO2 photocatalysis. We first tried to show the reaction mechanism of CO2 photocatalysis in the solitary presence of the most common reductants, H2, H2O (both gaseous and aqueous phases), CH4, and CH3OH. Then, a general mechanism has been suggested for CO2 conversion in the mixture of the reductants, based on the fact that in the photoreduction process of CO2, all of the reductants can be derived from one of them.