Surface enhanced infrared absorption spectroscopy: a valuable technique in understanding green chemistry

Date
2016
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University of Delaware
Abstract
Green chemistry is presenting itself to be an important field in the future. In studying green electrochemical reactions, knowledge and understanding of surface adsorbed species can be vital in tuning these systems. In situ surface enhanced spectroscopic investigations were conducted on several green systems. First, in situ surface enhanced spectroscopic and reactivity investigations of the electrochemical reduction of CO2 at low overpotentials (<0.7 V) were conducted on Cu surfaces. Vibrational bands corresponding to adsorbed hydrogen (Had) and carbon monoxide (COad) on Cu have been identified at 2090 cm -1 and 2060 cm-1, respectively. Spectroscopic investigations show that Had is capable of partially displacing COad; however, COad is unable to displace Had to any detectable level. The preferential adsorption of H over CO on Cu is consistent with the high selectivity towards the hydrogen evolution reaction at potentials > -0.8 V vs. RHE. CO2 reduction was also investigated on Sn under similar conditions. COad is tentatively identified at low potentials (-0.2 to -0.7 V) at approximately 1925 cm-1. Local bulk concentrations of formate were also identified at higher potentials (0.3 V). Similarly, in situ spectroscopic techniques were used to identify and follow surface concentrations of methylfuran in the reduction of furfural on Au. At low overpotentials (-0.2 V), local concentrations of 2-methylfuran are produced persist to potentials of 1.2 V. This high local concentration may lead to low performance of furfural reduction on Au. Combined, these studies show the capabilities of surface enhanced spectroscopic studies.
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