Copper is the only pure metal capable of electrochemically reducing carbon dioxide to hydrocarbons at significant reaction rates. It is therefore an archetypal catalyst for the electrochemical conversion of carbon dioxide to methane, ethylene, and other desirable hydrocarbons. Surface-adsorbed CO is generally considered an important on-pathway intermediate to hydrocarbons because its reduction corresponds to the potential-determining step of these reactions. To date, in situ spectroscopy of the copper/electrolyte contact has mostly been concerned with atop-bound CO, while bridge-bonded CO has received little attention. Using surface-selective infrared spectroscopy, we show for the first time that only a sub-population of the total surface-bound CO population is electrochemically active and leads to hydrocarbon formation: While atop-bound CO is readily reduced under cathodic polarization, bridge-bonded CO is stable, even at high cathodic potentials. We will further discuss the implications associated with the co-existence of the two distinct CO populations during CO reduction. Moreover, we explore the physical origins of the surprising electrochemical stability of bridge-bonded CO by DFT calculations.

Appearance of an electrochemically inert CO sub-population on Cu electrodes under CO reduction conditions in alkaline pH

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.