Unraveling the selectivity puzzle: To reconcile the experimental and computational discrepancy of CO₂ reduction to HCOOH and CO on Pb and Ag catalyst, we have incorporated solvation effects in our combined DFT/microkinetic study. Explicit solvation has a significant impact on reaction intermediate adsorption energies, resulting in CO selectivity on Ag and HCOOH selectivity on Pb surfaces, consistent with experimental findings.

Abstract

Herein, a comprehensive computational study of the impact of solvation on the reduction reaction of CO₂ to formic acid (HCOOH) and carbon monoxide on Pb(100) and Ag(100) surfaces is presented. Results further the understanding of how solvation phenomena influence the adsorption energies of reaction intermediates. We applied an explicit solvation scheme harnessing a combined density functional theory (DFT)/microkinetic modeling approach for the CO₂ reduction reaction. This approach reveals high selectivities for CO formation at Ag and HCOOH formation on Pb, resolving the prior disparity between ab initio calculations and experimental observations. Furthermore, the detailed analysis of adsorption energies of relevant reaction intermediates shows that the total number of hydrogen bonds formed by HCOO plays a primary role for the adsorption strength of intermediates and the electrocatalytic activity. Results emphasize the importance of explicit solvation for adsorption and electrochemical reaction phenomena on metal surfaces.