Continuous Carbon Dioxide Electroreduction to Concentrated Multi-carbon Products Using a Membrane Electrode Assembly

Electrochemical carbon dioxide (CO2) reduction is a promising strategy to synthesize valuable multi-carbon products (C2+) while sequestering CO2 and utilizing intermittent renewable electricity. For industrial deployment, CO2 electrolyzers must remain stable while selectively producing concentrated C2+ products at high rates with modest cell voltages. Here, we present a membrane electrode assembly (MEA) electrolyzer that converts CO2 to C2+ products. We perform side-by-side comparisons of state-of-the-art electrolyzer systems and find that the MEA provides the most stable cell voltage and product selectivity. We then demonstrate an approach to release concentrated gas and liquid products from the cathode outlet. This strategy achieves ∼50% and ∼80% Faradaic efficiency for ethylene and C2+ products, respectively, with cathode outlet concentrations of ∼30% ethylene and the direct production of ∼4 wt % ethanol. We characterize stability by operating continuously for 100 h, the longest stable ethylene production at current densities >100 mA cm−2 among reported CO2 electrolyzers.