Ultralow platinum loading and high catalytic performance at the membrane electrode assembly (MEA) level are essential for reducing the cost of proton exchange membrane fuel cells. The past decade has seen substantial progress in developing a variety of highly active platinum-based catalysts for the oxygen reduction reaction. However, these high activities are almost exclusively obtained from rotating disk electrode (RDE) measurements and have rarely translated into MEA performance. In this Review, we elucidate the intrinsic limitations that lead to a persistent failure to transfer catalysts’ high RDE activities into maximized MEA performance. We discuss catalyst-layer engineering strategies for controlling mass transport resistances at local catalyst sites, in the bulk of the catalyst layer and at the interfaces of the MEA to achieve high performance with ultralow platinum loading. We also examine promising intermediate testing methods for closing the gap between RDE and MEA experiments.

膜电极组件（MEA）级别的超低铂负载量和高催化性能对于降低质子交换膜燃料电池的成本至关重要。在过去的十年中，在开发用于氧还原反应的各种高活性铂基催化剂方面取得了实质性进展。但是，这些高活性几乎完全是通过旋转圆盘电极（RDE）测量获得的，很少转化为MEA性能。在本综述中，我们阐明了固有的局限性，这些局限性导致持续失败，无法将催化剂的高RDE活性转化为最大化的MEA性能。我们讨论了用于控制局部催化剂位置传质阻力的催化剂层工程策略，在大部分催化剂层中以及在MEA的界面处都可以实现超低铂负载的高性能。我们还研究了有希望的中间测试方法，以缩小RDE和MEA实验之间的差距。