Effect of Underpotentially Deposited Copper on Electrochemical Carbon Dioxide Reduction

The electrochemical carbon dioxide reduction reaction (ECO2RR) activity of monolithic copper powder, copper deposited underpotentially (Cu upd ) on 20 wt.% of carbon-supported commercial platinum, and that on 20 wt.% of carbon-supported synthesized palladium have been investigated in 0.5 M NaHCO 3 solution. A complex protocol has been developed to deposit copper atoms underpotentially on carbon-supported platinum and palladium nanoparticles in acidic media and subsequent transfer to 0.5 M NaHCO 3 for ECO2RR. Furthermore, the study was extended from a full monolayer to a partial monolayer. Results show that the copper monolayer is retained on the electrode surface even after rinsing with Ar-saturated deionized water and transferring to another electrolyte solution. Electrolysis experiments were carried out at three different potentials (-1.3 V, -1.55 V, and -1.8 V vs RHE) in CO 2 -saturated 0.5 M NaHCO 3 electrolyte solution, and the Faradaic efficiencies were compared. Interestingly, results suggest that the formate generation rate is more than twice on copper monolayer on platinum compared to monolithic copper. The electrochemical characterization was supplemented by detailed physico-chemical characterization by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses, not only to confirm the presence of copper but also its oxidation state.