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Degradation effects at the methanol inlet, outlet and center region of a stack MEA operated in DMFC

Dixon, D. and Wippermann, K. and Mergel, J. and Schoekel, A. and Zils, S. and Roth, C. (2011):
Degradation effects at the methanol inlet, outlet and center region of a stack MEA operated in DMFC.
In: Journal of Power Sources, Elsevier Science Publishing Company, pp. 5538-5545, 196, (13), ISSN 03787753,
[Online-Edition: http://dx.doi.org/10.1016/j.jpowsour.2011.02.007],
[Article]

Abstract

Ru dissolution is one of the key issues in direct methanol fuel cells (DMFC). A used DMFC stack membrane electrode assembly (MEA) was analyzed using different analytical techniques like X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM) and EDX and different regions probed in the process. Catalyst powder from e.g. like methanol inlet, outlet and center were investigated and compared with the as-received commercial electrocatalyst and the pristine MEA after manufacture. The large oxidized ruthenium fraction in the anode catalyst was found to play a significant role in particle growth and ruthenium dissolution. Crossover ruthenium from the anode side was found to be dispersed everywhere in the cathode in its oxidized form, and thus can have a significant effect on the oxygen reduction activity (ORR). Although with XRD no significant structural changes were observed for the different regions of the MEA, TEM and EDX analysis showed the preferential precipitation of the Ru at the methanol outlet.

Item Type: Article
Erschienen: 2011
Creators: Dixon, D. and Wippermann, K. and Mergel, J. and Schoekel, A. and Zils, S. and Roth, C.
Title: Degradation effects at the methanol inlet, outlet and center region of a stack MEA operated in DMFC
Language: English
Abstract:

Ru dissolution is one of the key issues in direct methanol fuel cells (DMFC). A used DMFC stack membrane electrode assembly (MEA) was analyzed using different analytical techniques like X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM) and EDX and different regions probed in the process. Catalyst powder from e.g. like methanol inlet, outlet and center were investigated and compared with the as-received commercial electrocatalyst and the pristine MEA after manufacture. The large oxidized ruthenium fraction in the anode catalyst was found to play a significant role in particle growth and ruthenium dissolution. Crossover ruthenium from the anode side was found to be dispersed everywhere in the cathode in its oxidized form, and thus can have a significant effect on the oxygen reduction activity (ORR). Although with XRD no significant structural changes were observed for the different regions of the MEA, TEM and EDX analysis showed the preferential precipitation of the Ru at the methanol outlet.

Journal or Publication Title: Journal of Power Sources
Volume: 196
Number: 13
Publisher: Elsevier Science Publishing Company
Uncontrolled Keywords: Degradation, DMFC, Ru dissolution, Area-specific, Inlet, Outlet, Stack ME
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Erneuerbare Energien
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 25 Feb 2013 12:27
Official URL: http://dx.doi.org/10.1016/j.jpowsour.2011.02.007
Identification Number: doi:10.1016/j.jpowsour.2011.02.007
Funders: Financial support of the BMBF under grant no. 03SF0324E is gratefully acknowledged.
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