Figure 1.

Schematics and nomenclature of prototypical CO₂ to CO electrolyzer configurations. The electrolyzer reported in this work is HOR|CEM|HCO₃^–, which uses a reactive carbon solution feedstock, a cation exchange membrane (CEM), and hydrogen oxidation at the anode to achieve low voltages and high CO₂ utilization efficiencies. The OER|AEM|CO₂ electrolyzer is a widely used architecture that uses a gaseous CO₂ feedstock. The OER|BPM|HCO₃^– electrolyzer also uses a reactive carbon solution feedstock, but the BPM needs to be optimized to achieve lower applied cell voltages. The lowest cell voltages reported in the literature for each electrolyzer architecture are indicated, but only the electrolyzers that produce j_CO >200 mA cm^–2 and CO₂ utilization efficiency >20% are considered.^9,19 The nomenclature follows “anode|membrane|cathode”.