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 CO 2 at low overpotentials (<0.7 V) was conducted on Cu surfaces. Vibrational bands corresponding to adsorbed hydrogen (H ad ) and carbon monoxide (CO ad ) on Cu have been identified at 2090 and 2060 cm –1, respectively. Spectroscopic investigations show that H ad is capable of partially displacing CO ad; however, CO ad 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.