Abstract
The recent demonstration of the reduced overpotential for the electrochemical conversion of CO2 to CO on the surface of oxidized copper films raised the question of possible interplay existing between the electroreduction of copper to its metallic form and the adsorption of CO2 on its surface. To study this effect and better understand the factor governing the CO2 adsorption on the surface of copper-based catalysts, we studied different copper vanadates oxides known for their ability to form metallic copper particles on their surface by electroreduction in Li+-containing salt. By controlling the vanadates framework, the potential at which metallic copper is formed can be controlled and selectively be varied around the CO2/CO standard potential. Studying the reduction behavior of these phases in CO2-saturated organic media containing Li+-salt, we demonstrate that the CO2 adsorption is correlated with the potential at which Cu particles are electrochemically formed. We further show that the CO2 adsorption is correlated with the oxidation of copper, indicating that the overpotential is controlled by the step corresponding to the formation of Cu(I)CO2− intermediate.