Dipartimento di Ingegneria dell'Innovazione, Universita del Salento, Via Monteroni, 73100 Lecce, Italy.
ChemSusChem. 2010 Jul 19;3(7):846-50. doi: 10.1002/cssc.201000048.
Nafion contamination by ferrous-alloy corrosion products, resulting in dramatic drops of the Ohmic potential, is a suspected major failure mode of polymer electrolyte membrane fuel cells that make use of metallic bipolar plates. This study demonstrates the potential of scanning transmission X-ray microscopy combined with X-ray absorption and fluorescence microspectroscopy for exploring corrosion processes of Ni and Fe electrodes in contact with a hydrated Nafion film in a thin-layer cell. The imaged morphology changes of the Ni and Fe electrodes and surrounding Nafion film that result from relevant electrochemical processes are correlated to the spatial distribution, local concentration, and chemical state of Fe and Ni species. The X-ray fluorescence maps and absorption spectra, sampled at different locations, show diffusion of corrosion products within the Nafion film only in the case of the Fe electrodes, whereas the Ni electrodes appear corrosion resistant.
铁合金腐蚀产物污染 Nafion 会导致欧姆电势急剧下降，这是使用金属双极板的聚合物电解质膜燃料电池的一种主要失效模式。本研究表明，扫描透射 X 射线显微镜结合 X 射线吸收和荧光微光谱学在探索与水合 Nafion 薄膜接触的 Ni 和 Fe 电极的腐蚀过程方面具有潜力，该薄膜位于薄层电池中。与相关电化学过程相关的 Ni 和 Fe 电极以及周围 Nafion 膜的成像形态变化与 Fe 和 Ni 物种的空间分布、局部浓度和化学状态相关联。在不同位置采集的 X 射线荧光图谱和吸收光谱显示，只有在 Fe 电极的情况下，腐蚀产物才会在 Nafion 膜内扩散，而 Ni 电极则表现出耐腐蚀。
