Catalyst microstructure examination of PEMFC membrane electrode assemblies vs. time

A series of single-cell, hydrogen-air proton exchange membrane fuel cells (PEMFCs) was operated for different lengths of time, namely, 200, 500, 700, and 1000 h. A group of reproducible and identical membrane electrode assemblies (MEAs) was used for those tests. Cell performance was studied by exami...

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Bibliographic Details
Published inJournal of the Electrochemical Society Vol. 151; no. 1; pp. A48 - A52
Main Authors Cheng, Xuan, Chen, Ling, Peng, Cheng, Chen, Zhiwu, Zhang, Ying, Fan, Qinbai
Format Journal Article
LanguageEnglish
Published Pennington, NJ Electrochemical Society 2004
Subjects
Applied sciences
Energy
Energy. Thermal use of fuels
Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc
Exact sciences and technology
Fuel cells
Performance evaluation
Electrocatalysis
Membrane electrode
Energetic efficiency
Electrode life
Microstructure
Current density
Proton exchange membrane fuel cells
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Summary:A series of single-cell, hydrogen-air proton exchange membrane fuel cells (PEMFCs) was operated for different lengths of time, namely, 200, 500, 700, and 1000 h. A group of reproducible and identical membrane electrode assemblies (MEAs) was used for those tests. Cell performance was studied by examining the cell polarization curves. After various lifetime tests, each MEA was cross-cut and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy, and Raman techniques to investigate any changes in catalyst structure and morphology, as well as particle size and chemical composition. The average particle size of the catalysts was calculated from XRD results and was found to increase with cell operating time. In addition, the agglomeration in nanometer-sized catalyst particles was observed from TEM analysis after prolonged cell operation. Ruthenium oxide was identified from Raman spectra of the anode catalyst from the tested MEAs, while no oxides were found on the cathode catalyst at the cell operating voltage. It is possible that the formation of metal oxides at the surface of the anode catalyst led to larger particles and ultimately resulted in the decrease of catalyst activity. This might be responsible for the slightly degraded cell performance following 700 h of operation.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
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content type line 23
ISSN:0013-4651
1945-7111
DOI:10.1149/1.1625944