Deciphering the Selectivity of the Electrochemical CO₂ Reduction to CO by a Cobalt Porphyrin Catalyst in Neutral Aqueous Solution: Insights from DFT Calculations.

ABSTRACT: Density functional theory (DFT) calculations were conducted to investigate the cobalt porphyrin-catalyzed electro-reduction of CO₂ to CO in an aqueous solution. The results suggest that Co^II -porphyrin (Co^II -L) undertakes a ligand-based reduction to generate the active species Co^II -L⋅^- , where the Co^II center antiferromagnetically interacts with the ligand radical anion. Co^II -L⋅^- then performs a nucleophilic attack on CO₂ , followed by protonation and a reduction to give Co^II -L-COOH. An intermolecular proton transfer leads to the heterolytic cleavage of the C-O bond, producing intermediate Co^II -L-CO. Subsequently, CO is released from Co^II -L-CO, and Co^II -L is regenerated to catalyze the next cycle. The rate-determining step of this CO₂ RR is the nucleophilic attack on CO₂ by Co^II -L⋅^- , with a total barrier of 20.7 kcal mol^-1 . The competing hydrogen evolution reaction is associated with a higher total barrier. A computational investigation regarding the substituent effects of the catalyst indicates that the CoPor-R3 complex is likely to display the highest activity and selectivity as a molecular catalyst.

SUBMITTER: Cao YC 

PROVIDER: S-EPMC9900731 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature