Benefits of platinum deposited in the polymer membrane subsurface on the operational flexibility of hydrogen fuel cells

The effects of electroless Pt layers (<80 μgPt cm−2) in the membrane subsurface on hydrogen crossover, ORR kinetics, and overall fuel cell performance are closely investigated. The electroless Pt layer in the membrane subsurface reduces gas crossover for a 17 μm thick membrane in an inversely proportional relationship to the loading, yielding up to >65% reduction. High electroless Pt layer loading reduces proton conductivity and results in less optimal ORR kinetic performance. Given the relationship between kinetic performance, exchange current density, and proton concentration, the impact of electroless Pt layer loading on proton concentration is determined. This correlation sheds light on the relationship between proton concentration, proton conductivity, and Pt loading, and can be useful as a probe for proton concentration diagnostic examinations. Hydrogen fuel cell tests reveal that with an additional membrane Pt loading of <20 μgPt cm−2, the performance of GDE-based MEAs at low humidity are improved in both polarization and long-term humidity cycling tests, while the performance under wet conditions is still nearly identical to the baseline. This suggests that the addition of electroless Pt in the membrane subsurface at such loadings enhances the operational flexibility of hydrogen fuel cells and reduces hydrogen crossover effects.