our spectra. When comparing reference spectra of different anions, this is the only anion that displays an absorption above 1700 cm-1. Other notable absorption peaks of oxalate are observed at 1457, 1274, and 821 cm-1. While the first two peaks are likely present, their signals might be obscured due to strong overlap with (bi)carbonate peaks. The latter peak is not easily distinguishable in the spectra due to significant baseline attenuation. The formation of oxalate could potentially result from the self-coupling of the adsorbed *CO2 - species, a mechanism also proposed by Kamet et al3 over a lead electrode in acetonitrile. Formation of Formate The peak observed around 1330 cm-1 in the in-situ spectra of Figures 6.2 and 6.3 introduces a novel feature in our analysis. Among the investigated reference compounds, the only one that displayed a somewhat similar absorption near this wavelength was BMMIM HCOO (formate). The formation of this compound aligns with the NMR analysis of the solid product, which, in addition to bicarbonate, revealed the presence of formate. While the overlap of several bands assigned to bicarbonate and/or oxalate complicates the assignment of other spectral features expected for formate, the prominence of the 1330 cm-1 peak position and the NMR data provide confidence that formate is indeed generated in the reaction. The co-occurrence of oxalate, formate, and CO was also suggested by Amatore and Saveant23 in aprotic media with limited proton availability.The occurrence of oxalate, formate and CO was also argued by Amatore and Saveant 31 in aprotic media of low proton availability.
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