Analyzing Structural Changes of Fe鈥揘鈥揅 Cathode Catalysts in PEM Fuel Cell by M枚脽bauer Spectroscopy of Complete Membrane Electrode Assemblies
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- 作者：Ulrike I. Kramm ; Michel Lef猫vre ; Peter Bogdanoff ; Dieter Schmei脽er ; Jean-Pol Dodelet
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2014
- 出版时间：November 6, 2014
- 年：2014
- 卷：5
- 期：21
- 页码：3750-3756
- 全文大小：415K
- ISSN：1948-7185
文摘
The applicability of analyzing by M枚脽bauer spectroscopy the structural changes of Fe鈥揘鈥揅 catalysts that have been tested at the cathode of membrane electrode assemblies in proton exchange membrane (PEM) fuel cells is demonstrated. The M枚脽bauer characterization of powders of the same catalysts was recently described in our previous publication. A possible change of the iron species upon testing in fuel cell was investigated here by M枚脽bauer spectroscopy, energy-dispersive X-ray cross-sectional imaging, and neutron activation analysis. Our results show that the absorption probability of 纬 rays by the iron nuclei in Fe鈥揘鈥揅 is strongly affected by the presence of Nafion and water content. A detailed investigation of the effect of an oxidizing treatment (1.2 V) of the non-noble cathode in PEM fuel cell indicates that the observed activity decay is mainly attributable to carbon oxidation causing a leaching of active iron sites hosted in the carbon matrix.