Advances in the development of precious-group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) in fuel cell cathodes have produced active catalysts that reduce the performance gap to the incumbent Pt-based materials. However, utilization of state-of-the-art PGM-free catalysts for commercial applications is currently impeded by their relatively low durability. Methods designed to study catalyst degradation in the operation of fuel cells are therefore critical for understanding durability issues and, ultimately, their solutions. Here we report the use of Fourier-transform alternating current voltammetry as an electrochemical method for accurate quantification of the electrochemically active site density of PGM-free cathode catalysts, and to follow their degradation in situ during the operation of polymer electrolyte fuel cells. Using this method, we were able to quantify the electrochemical active site density, which will enable the elucidation of degradation mechanisms of PGM-free ORR catalysts in situ in fuel cells.

用于燃料电池阴极氧还原反应 (ORR) 的无贵族金属 (PGM-free) 催化剂的开发进展已产生活性催化剂，可缩小与现有 Pt 基材料的性能差距。然而，目前最先进的无 PGM 催化剂在商业应用中的使用受到其相对较低的耐久性的阻碍。因此，旨在研究燃料电池运行中催化剂降解的方法对于了解耐久性问题以及最终的解决方案至关重要。在这里，我们报告了使用傅里叶变换交流伏安法作为一种电化学方法，用于准确量化无 PGM 阴极催化剂的电化学活性位点密度，并在聚合物电解质燃料电池运行期间跟踪它们的原位降解。