Achieving High-Power PEM Fuel Cell Performance with an Ultralow-Pt-Content Core–Shell Catalyst

The high-power performance of proton exchange membrane fuel cells (PEMFC) decreases as the Pt loading or Pt surface area decreases due to oxygen transport constraints. This has limited the Pt reduction of a fuel cell below the current ∼0.2 mgPt/cm2MEA. In this paper, the performance of a Pt-monolayer core–shell catalyst (PtML/Pd/C) was studied with a particular focus on high-current-density operation. Although conventional Pt/C electrodes with low Pt loading showed a substantial voltage falloff at high current densities, PtML/Pd/C showed superior performance due to its greater Pt surface area. We show that Pt loading can be reduced to a level as low as 0.025 mgPt/cm2 without noticeable transport-related losses. This suggests considerable potential for further fuel cell cost reduction. The performance and microscopic properties of the catalyst were also studied after accelerated stability tests. The degradation mechanism and pathways for future development are also discussed.