Impact of Platinum Loading and Layer Thickness on Cathode Catalyst Degradation in PEM Fuel Cells

In this work we investigate the effect of platinum loading and layer thickness on cathode catalyst degradation by a comprehensive in situ STEM-EDS characterization. To decouple from each other, experiments were categorized two sets, with loadings varying between 0.1 0.4 mg Pt cm −2 : (i) Samples constant Pt/C ratio thus thickness, (ii) samples ratios, achieved dilution bare carbon, to maintain at different loadings. Every MEA was subjected an accelerated stress test, where cell operated for 45,000 cycles 0.6 0.95 V. Regardless ratio, higher relative loss electrochemically active surface area measured lower measurements showed that mainly lost close cathode—membrane interface concentration driven 2+ ion flux into membrane. The size Pt-depletion zone has shown be independent overall hence causing low electrodes, as depletion accounts larger fraction layer.