Electrochemistry Laboratory, Paul Scherrer Institut, Villigen PSI 5232, Switzerland.
Department of Information Technology and Electrical Engineering, ETH Zürich, Zürich 8092, Switzerland.
ACS Appl Mater Interfaces. 2023 Jun 7;15(22):26538-26553. doi: 10.1021/acsami.3c00420. Epub 2023 May 25.
The complex nature of liquid water saturation of polymer electrolyte fuel cell (PEFC) catalyst layers (CLs) greatly affects the device performance. To investigate this problem, we present a method to quantify the presence of liquid water in a PEFC CL using small-angle X-ray scattering (SAXS). This method leverages the differences in electron densities between the solid catalyst matrix and the liquid water filled pores of the CL under both dry and wet conditions. This approach is validated using ex situ wetting experiments, which aid the study of the transient saturation of a CL in a flow cell configuration in situ. The azimuthally integrated scattering data are fitted using 3D morphology models of the CL under dry conditions. Different wetting scenarios are realized in silico, and the corresponding SAXS data are numerically simulated by a direct 3D Fourier transformation. The simulated SAXS profiles of the different wetting scenarios are used to interpret the measured SAXS data which allows the derivation of the most probable wetting mechanism within a flow cell electrode.
聚合物电解质燃料电池（PEFC）催化剂层（CL）中液体水饱和度的复杂性质极大地影响了器件性能。为了研究这个问题，我们提出了一种使用小角 X 射线散射（SAXS）定量分析 PEFC CL 中液体水存在的方法。该方法利用了在干燥和湿润条件下，固体催化剂基质和 CL 中充满液体水的孔之间的电子密度差异。该方法通过使用原位流动池配置中 CL 瞬态饱和度的湿态实验进行验证。使用干燥条件下 CL 的 3D 形态模型对轴向积分散射数据进行拟合。在计算机中实现不同的润湿情况，并通过直接 3D 傅立叶变换对相应的 SAXS 数据进行数值模拟。使用不同润湿情况的模拟 SAXS 轮廓来解释测量的 SAXS 数据，这允许在流动池电极内推导出最可能的润湿机制。
