CO2 Reduction Mechanism on the Pb(111) Surface: Effect of Solvent and Cations

The Pb electrode is the most efficient and selective catalyst in reducing CO2 into HCOOH; however, the reaction mechanism remains elusive. Herein, we have investigated the mechanism of CO2 electroreduction to HCOOH on the Pb(111) surface using density functional theory calculations. We find that the effects of solvation and cations lead to different active intermediates for CO2 electroreduction (HCOO in gas-phase condition, both HCOO and COOH in solvent condition, and COOH in cation solution). In particular, the size and hydrophilic/hydrophobic nature of the cations are found to significantly affect the reaction selectivity and efficiency of CO2 electroreduction at different overpotentials. These findings rationalize several experimental observations and contribute to a thorough understanding of CO2 electroreduction.