Electrochemical Conversion of CO2 from Direct Air Capture Solutions

Integrating alkaline capture of CO2 from air with electrochemical conversion of the obtained (bi)carbonate solution is among the most promising strategies in carbon capture and utilization (CCU) technologies. Thus far, this approach has received little or no attention because of the challenging conversions of CO2 from bicarbonate solutions because of the parasitic hydrogen evolution reaction (HER). Very recently, thanks to the advances in reactor design and the understanding of the mechanism of bicarbonate electrolysis, promising results were obtained in terms of performance (i.e., >60% FE toward formate or CO at >50 mA cm–2) and as such provided us with the required know-how to, for the first time, construct and validate a proof-of-concept experimental setup where CO2 is captured from air, in the form of a (bi)carbonate solution, through direct air capture and then converted to formate and CO in a zero-gap flow electrolyzer. The presented results provide a new opportunity for upscaling the electrochemical conversion of CO2, since integrating the capture and the conversion steps is a crucial step to enhance the economic feasibility of the CCU technology (energy-intensive CO2 separation can be avoided) and thus increase its chances of industrial implementation.