Computational Exploration of the Direct Reduction of CO2 to CO Mediated by Alkali Metal and Alkaline Earth Metal Chloride Anions

We present a computational survey of the reduction of CO2 to CO by alkali metal and alkaline earth metal chloride anions in the gas phase, uncovering also mechanistic aspects on the selective tuning between oxalate and carbonate products relevant to chemical or electrochemical processes. The reduction of a single CO2 molecule is typically endothermic, whereas the corresponding disproportionation reaction involving two molecules is exothermic. Our computational results suggest consistent periodic trends with reaction energies being highest for elements toward the center of each group. The factors governing these trends are discussed, in particular, the covalent contributions to bonding in these highly ionic species.