Electrolytic Conversion of Bicarbonate Solutions to CO at >500 mA cm-2 and 2.2 V

Electrolyzers that reduce carbon dioxide (CO2) into chemicals and fuels often use high-purity gaseous CO2 feedstocks that need to be isolated from upstream carbon capture units. If CO2 were to be captured directly from air, the eluent is likely to be an aqueous solution rich in bicarbonate ions (HCO3-). This scenario provides the impetus to electrolytically reduce these bicarbonate-rich carbon capture solutions into the same products as a CO2 electrolyzer. We report here an electrolyzer configuration that couples the conversion of bicarbonate to CO at the cathode with hydrogen oxidation at an anode. This unique system is capable of reaching a commercially-relevant current density of 500 mA cm-2 at merely 2.2 V, which is >0.5 V more efficient than any other reported electrolyzer that reduces HCO3- or CO2 at these current densities.