Electrolyte Effects on the Reduction Potential and Carbon Dioxide Binding Affinity of Quinones

Abstract

CO2 capture and concentration (CCC) is critical to carbon negative technologies and can reduce or eliminate carbon emission of current industrial processes. A popular method for electrochemically-driven CCC uses redox carriers that bind and release CO2 depending on their oxidation state. Two critical properties of redox carriers are the reduction potential required to ‘activate’ the redox carrier for CO2 capture and the CO2 binding constant. The former impacts the stability of the redox carrier towards oxidants such as O2, while the later determines the concentration levels of CO2 that can be captured. Quinones have been heavily studied as redox carriers. However, the impact of electrolyte on these properties has not been systematically explored. The reduction potential and the CO2 binding constant for 6 quinones and 3 alkylammonium hexafluorophophate electrolytes are quantified in acetonitrile. While alkylammonium cations are often considered inert and interchangeable, our studies show up to 100 mV changes in reduction potential with minimal changes to the CO2 binding constant.