Electrochemical Conversion of CO2into Organic Carbonates—Products and Intermediates

In this work, we report a spectro-electrochemical study of the synthesis of organic carbonates from CO2 and methanol. The obtained spectra reveal the presence of a species with vibrational features at 1673 and 1281 cm-1 that originate from the reaction of methanol with CO from CO2 electrochemical reduction. Both methanol activation and the formation of CO from CO2 (rather than CO2•- as considered in previous literature) were necessary conditions for the formation of this product. This species was identified as an alkyl ammonium methyl carbonate and was found on three different electrode materials. Although dimethyl carbonate was not directly identified under the studied conditions, it was observed that it decomposes under an effect of the applied potential to the same alkyl ammonium methyl carbonate. Therefore, although it appears to be possible to synthesize dimethyl carbonate electrochemically from CO2 and methanol, dimethyl carbonate is not stable under the reductive conditions considered.