By contrast, using the NiNC-PANI reference catalysts, FECO > 90% was only achieved at low currents of -50 mA cm -2 , with loading having minor impact (Figure ). The polarization curve and jCO are shown in the SI (Supplementary Figure ). We measured double layer currents at different scan rates ( Supplementary Figure ) and we found that the interfacial capacitance does correlate with the NiNC-IMI loading, yet does not for NiNC-PANI (Supplementary Figure ), further evidence for limited microporous site accessibility.