Fig. 2. 1D continuum modelling results of the BPMEA.

a Modelled and experimental Faradaic efficiencies of CO for catalyst layer (CL) incorporated with Sustainion (Sus-CL) or Nafion (Naf-CL) as a function of current densities. Comparison of b pH, c (bi)carbonate concentrations, and d CO₂ local concentration across CLs at 100 mA cm⁻². Profiles of e pH, f (bi)carbonate ions, and g CO₂ local concentration across CEL and Sus-CL as a function of proton transference numbers. The bipolar junction is located at x = 0 μm, and the CEL|CL is located at x = 75 μm. The concentration profiles of the CEL for c and d are presented in Supplementary Fig. S2, and not shown here for clarity.