Considering the effect of increased Fe-N-C loading, the amount of Fe dissolu�on follows a linear trend over the ini�al 50 CVs (Figure ). The percentage of total Fe detected increases from 7.5±2.9% to 15.2±3.3% as catalyst loading increases from 0.05 to 0.40 mg Fe-N-C cm geo , with 11.3±5.6% at 0.20 mg Fe-N-C cm geo (Figure ). This finding appears counterintui�ve as one would expect either an equivalent percentage of Fe detected rela�ve to the loading, or even a reduced percentage of detected Fe, due to reduced ac�ve site u�liza�on with increasing thickness of the catalyst layer. It is also worth no�ng that there is a constant 130 ng Fe g FeNC -1 s -1 57 Fe concentra�on observed when held at 0.9 V RHE (Figure ), which was also the OCP of the TAP 900@ 57 Fe catalyst.