Electrolytic Conversion of Bicarbonate into CO in a Flow Cell

Summary Electrolyzers designed to convert CO2 into carbon products typically rely on a gaseous CO2 feedstock or CO2-saturated electrolyte. We show herein that aqueous HCO3− solutions can also be electrochemically converted into CO gas at meaningful rates in a flow cell containing a bipolar membrane (BPM). Electrolysis upon a N2-saturated 3.0 M KHCO3 solution yields CO with a faradic efficiency of 81% at 25 mA cm−2 and 37% at 100 mA cm−2, outputs that are comparable to the analogous experiment where the bicarbonate solution is saturated with gaseous CO2. This electrolytic process is made possible by the membrane delivering protons for reaction with the bicarbonate feed to form electrocatalytically active CO2. This reaction pathway offers the potential to use electrolysis to bypass the thermally intensive step of extracting CO2 from HCO3− solutions generated in carbon-capture schemes.