Combining Microscopy and Synchrotron X-Ray Diagnostics to Study Catalyst Degradation in PEFCs

作者：A. Mufundirwa, Hiroyuki Iwamoto, Y. Fukunaga, Tomokazu Yamamoto, Satoru Yoshioka, Yasukazu Murakami, Takeharu Sugiyama, Noboru Ohta, Hiroshi Sekiguchi, K. Tono · 发表于：ECS Meeting Abstracts · 年份：2024 · DOI：10.1149/ma2024-02443080mtgabs

Polymer electrolyte fuel cells (PEFCs) suffer from performance degradation during operation due to transformations in the catalyst (Pt or Pt/Co particles) and their carbon support. However, nano-structural diagnostic methods are not readily applicable in the humid, high-temperature, and gas environments of PEFC operation. This hinders elucidation of the mechanisms behind catalyst property evolution (size, shape, lattice parameters), which directly affects the electrocatalytic surface area (ECSA), a critical factor in catalyst performance.1 Here, we employ a combined methodology to study the changes in catalyst particle properties using identical location scanning transmission electron microscopy (IL-STEM)2 and Operando synchrotron X-ray measurements, particularly small angle X-ray scattering technique (SAXS)3. While IL-STEM offers high-resolution imaging for estimating local particle size, shape, and lattice parameters, SAXS provides statistically reliable data on the overall particle size distribution.4 These complementary techniques, with their inherent strengths, allow for a comprehensive understanding of the mechanisms involved during particle transformation. Electrochemical cycling of the catalysts was performed using a square wave potential pattern cycling between 0.6 and 1.0 VRHE at 6 seconds/cycle. A gold STEM grid was mounted on a specially designed working electrode for electrochemical cycling, which is performed ex-situ. STEM images, of the same areas, before a...