Exploration of the basic reactant in CO2 photoreduction: New insights from photophysics and photochemistry

Abstract Photoreduction of CO 2 as an attractive path for CO 2 conversion has drawn widespread interest. Experiments demonstrating the photoreduction of CO 2 are conducted in water solution in the excited state, and solvent molecules play a major role in the reaction mechanism. Thus, a simple gas-phase CO 2 model of the ground-state cannot fully demonstrate the characteristics of aqueous CO 2 and the mechanisms of CO 2 photoreduction in the excited state. A deep understanding of the characteristics of aqueous CO 2 as the basic reactant is the cornerstone for the development of photocatalysts. In this study, a systemic investigation involving photophysics and photochemistry was performed to determine its existential status, kinetic and thermodynamic characteristics. In the excited state, H 2 CO 3 as the main inorganic carbon in pure water should be considered in the photoreduction of CO 2 , and the development of photocatalysts should compatible with its characteristics.