Carbon supported Ru–Se as methanol tolerant catalysts for DMFC cathodes. Part II: preparation and characterization of MEAs |
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Authors: | K Wippermann B Richter K Klafki J Mergel G Zehl I Dorbandt P Bogdanoff S Fiechter S Kaytakoglu |
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Affiliation: | (1) IEF-3, Forschungszentrum Jülich GmbH, 52425 Julich, Germany;(2) Hahn-Meitner-Institut-Berlin, Glienicker Str. 100, 14109 Berlin, Germany;(3) Faculty of Engineering and Architecture, Anadolu University, Eskisehir, 26470, Turkey |
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Abstract: | Cathode catalyst layers were prepared and characterized as part of membrane electrode assemblies (MEA) and catalyst coated
membranes (CCM) on the basis of carbon supported methanol tolerant RuSe
x
catalysts. Preparation parameters varied were: catalyst loading (0.5–2 mg RuSe
x
cm−2), PTFE content (0, 6, 18 wt.%), carbon support (Vulcan XC 72 or BP2000), and fraction of RuSe
x
in the carbon supported catalysts (20, 44, 47 wt.%). The MEAs and cathode catalyst layers were electrochemically characterized
under Direct Methanol Fuel Cell (DMFC) operating conditions by recording polarization curves, galvanostatic measurements,
and impedance spectra. The morphology of the catalyst layers was investigated by means of confocal laser scan microscopy (CLSM),
scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) measurements. MEAs
with Ru(44.0 wt.%)Se(2.8 wt.%)/VulcanXC72 cathode catalyst achieved the highest performance of all RuSe
x
catalysts investigated, i.e. ∼40 mW cm−2 at 80 °C under ambient pressure and λMeOH = λair = 4. This is 40% of the value obtained with commercial platinum cathode catalyst under the same operating conditions. The
RuSe
x
catalysts investigated are stable over a period of more than 1,000 h. This was confirmed by TEM and XRD measurements, where
no increase in mean RuSe
x
particle size (∼5 nm) after fuel cell operation was found. Enhancement of specific catalyst activity, mass transport, and
active surface offer potential for a further improvement of RuSe
x
catalyst layers. |
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Keywords: | Ru-Se Methanol tolerant catalysts DMFC cathodes Surface roughness XRD CLSM SEM TEM |
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