Screening Anion Exchange Membranes for CO2 Electrolysis

In membrane electrode assembly (MEA) electrolyzers for the electrochemical CO2 reduction reaction (CO2RR) using alkaline or neutral electrolytes, anion exchange membranes (AEMs) play a critical role in determining mass transfer, energy efficiency, and stability within the reaction system. In this study, we compared commercial AEMs from three brands─Piperion, Sustainion, and Fumasep─to identify the membrane that offers the best CO2RR performance. The primary differences in the effects of AEMs on the CO2RR are reflected in energy efficiency, Faradaic efficiency of products, and device stability. Among all the AEMs, Fumasep 3–50 provides the highest energy efficiency, attributed to the excellent conductivity of the organic monomers composing it. Meanwhile, Piperion A20 and Sustainion X-37 grade RT demonstrate superior Faradaic efficiency and cation barrier properties, thereby enabling long-term CO2RR operation. This work screens available commercial AEMs for CO2 electrolysis and identifies the essential parameters for the CO2RR, providing valuable insights for the electrochemical CO2 reduction field.