Identical location scanning electron microscopy (IL-SEM) and transmission electron microscopy (IL-TEM) are used to follow the degradation of the cathodic catalytic Pt/C electrode layer in a real proton-exchange membrane fuel cell under operation. During an accelerated stress test, mimicking start-up/shutdown conditions, the IL-SEM analysis reveals the formation and growth of cracks in the electrode layer, which expose the underlying membrane, leading to the creation of isolated islands of the electrode layer that tend to delaminate from the membrane. This is found to correlate with a 2- to 4-fold increase of the cell resistance. Nanoscale IL-TEM imaging shows that the diameter of the primary particles of the carbon support shrinks by on average 20%. Consequently, the Pt particles on the support agglomerate and grow by 63% contributing to an observed 65% loss in the electrochemically active surface area. The corrosion of the structural weak points of the carbon support leads to structural collapse. This collapse of the porous structure and weakening of connective points within the cathodic catalyst layers coincide with increased cell and mass transport resistance, resulting in large performance losses. While similar effects have been indicated before, the IL microscopy analysis provides a deeper understanding of the underlying mechanisms and the connection between morphological changes and fuel cell performance losses.

中文翻译：

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PEMFC 中的碳支撑腐蚀，随后进行相同位置的电子显微镜检查

使用同位扫描电子显微镜 (IL-SEM) 和透射电子显微镜 (IL-TEM) 来跟踪实际运行中的质子交换膜燃料电池中阴极催化 Pt/C 电极层的降解。在模拟启动/关闭条件的加速应力测试过程中，IL-SEM 分析揭示了电极层中裂纹的形成和生长，这些裂纹暴露了下面的膜，导致电极层上形成孤岛，这些孤岛往往会导致从膜上分层。发现这与细胞电阻增加 2 至 4 倍相关。纳米级 IL-TEM 成像显示，碳载体的初级颗粒直径平均缩小了 20%。因此，载体上的 Pt 颗粒聚集并生长了 63%，导致电化学活性表面积损失了 65%。碳载体的结构薄弱点的腐蚀导致结构倒塌。多孔结构的塌陷和阴极催化剂层内连接点的弱化与电池和传质阻力的增加同时发生，导致巨大的性能损失。虽然之前已经表明了类似的影响，但 IL 显微镜分析可以更深入地了解潜在机制以及形态变化和燃料电池性能损失之间的联系。