To demonstrate the practical diagnostic value of the CCC and stoich -based electrolyzer cell performance analysis, we consider the cell data in FECO vs. CCC plots (Figure ). We qualitatively distinguish distinct regions (green, yellow, red) that we associate with distinct inplane and through-plane transport as well as distinct catalytic CO2 conversion. Operating electrolyzer conditions with CCC ~ 1 and low FECO < 60% (yellow in Figure , Figure )