Mechanistic insights into electrochemical reduction of CO ₂ over Ag using density functional theory and transport models

Significance Chemical storage of solar energy can be achieved by electrochemical reduction of CO 2 to CO and H 2 , and subsequent conversion of this mixture to fuels. Identifying optimal conditions for electrochemical cell operation requires knowledge of the CO 2 reduction mechanism and the influence of all factors controlling cell performance. We report a multiscale model for predicting the current densities for H 2 and CO formation from first principles. Our approach brings together a quantum-chemical analysis of the reaction pathway, a microkinetic model of the reaction dynamics, and a continuum model for mass transport of all species through the electrolyte. This model is essential for identifying a physically correct representation of product current densities dependence on the cell voltage and CO 2 partial pressure.