CO2 Reduction on Cu at Low Overpotentials with Surface-Enhanced in Situ Spectroscopy

In situ surface-enhanced spectroscopic and reactivity investigations of the electrochemical reduction of CO2 at low overpotentials (<0.7 V) was conducted on Cu surfaces. Vibrational bands corresponding to adsorbed hydrogen (H-ad) and carbon monoxide (COad) on Cu have been identified at 2090 and 2060 cm(-1), respectively. Spectroscopic investigations show that Had is capable of partially displacing COad; however, COad is unable to displace H-ad to any detectable level. The preferential adsorption of H over CO on Cu is consistent with the high selectivity toward the hydrogen evolution reaction at potentials >-0.8 V versus reversible hydrogen electrode.