Organic Non-Nucleophilic Electrolyte Resists Carbonation During Selective CO2 Electroreduction

12 January 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The spontaneous reaction of CO2 with water and hydroxide to form (bi)carbonates in alkaline aqueous electrolytes com-promises the energy and carbon-efficiency of CO2 electrolyzers. We hypothesized that electrolyte carbonation could be mitigated in an aprotic solvent with low water content, by employing an exogenous non-nucleophilic acid capable of driving proton transfer without parasitic capture of CO2 by its conjugate base. However, it is unclear whether such an electrolyte design could engender high CO2 reduction selectivity and low electrolyte carbonation. We herein report selective CO2 electro-reduction on polycrystalline Au catalyst using dimethyl sulfoxide as the solvent and acetic acid / acetate as the proton donating medium with low carbonate formation. CO2 is reduced to CO with over 90% faradaic efficiency at potentials relative to the reversible hydrogen couple that are comparable to those in neutral aqueous electrolytes. 1H and 13C NMR studies demonstrate that only millimolar concentrations of bicarbonates are reversibly formed, that the proton activity of the medium is largely unaffected by exposure to CO2, and that low carbonation is maintained upon addition of 1 M water. This work demonstrates that electrolyte carbonation and efficient CO2 reduction can be decoupled from each other in an aprotic solvent, offering new electrolyte design principles for low-temperature CO2 electroreduction systems.


non-aqueous electrochemistry
aprotic solvent
carbon dioxide reduction
proton donor

Supplementary materials

Supplementary Information
Supplementary Information for "Organic Non-Nucleophilic Electrolyte Resists Carbonation During Selective CO2 Electroreduction"


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.