Modeling the effect of surface CO coverage on the electrocatalytic reduction of CO₂ to CO on Pd surfaces

Electrocatalytic reduction of CO2 has attracted considerable attention recently, and it was found experimentally that Pd could show activity for the electroreduction of CO2 to CO. However, theoretical studies showed that the adsorption of CO on Pd surfaces is strong and the coverage of CO is high, indicating that the interactions between the neighboring adsorbed CO and other reaction intermediates on the Pd surfaces cannot be neglected. Here, with density functional theory calculations and utilizing the Sabatier analysis method, we find that an adsorbate-adsorbate interaction is playing a crucial role in the modeling of the electrocatalytic reduction of CO2 to CO on Pd surfaces, whilst the reaction rates obtained by neglecting the interactions between the surface adsorbates are substantially lower than those reported in the experiments. Upon analyzing the interactions quantitatively and using a self-consistent iterative microkinetic modeling method, we find that the active site for CO2 electroreduction is Pd(111) at different potentials applied. Our modeling results provide a reasonable computational interpretation for the electroreduction of CO2 to CO on Pd.