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Structural and electrochemical investigation of binary mixtures of carbon-supported Pt and Ru catalysts for PEM fuel cells

Mazurek, Marian and Benker, Nathalie and Roth, Christina and Fuess, Hartmut (2006):
Structural and electrochemical investigation of binary mixtures of carbon-supported Pt and Ru catalysts for PEM fuel cells.
In: Fuel cells, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, pp. 208-213, 6, (3-4), [Article]

Abstract

Commercially available carbon-supported pure Pt and pure Ru catalysts were heat treated in order to modify their individual particle sizes, mixed in a mortar and tested for their suitability as anode catalysts in polymer electrolyte fuel cells (PEMFCs). The procedure chosen for mixing monometallic catalysts should bring more flexibility to the preparation of catalysts, which could thus be easily adjusted to the working conditions. The catalyst mixtures were structurally characterized using a combination of X-ray diffraction (XRD) and transmission electron microscopy (TEM), and indicated an increase in particle size with heat treatment temperature, while the size distribution remained sufficiently narrow. The particle size effect on the resulting activity of the catalyst mixtures was investigated by current-voltage measurements (U/i curves) in single cell fuel cells. A mixture of the as-received platinum and ruthenium gave the best results, which was almost comparable to a commercial Pt-Ru alloy catalyst purchased from E-TEK inc. Only a minor decrease in cell performance was seen during long term operation. Following operation, the X-ray diffraction patterns show reflections of the Pt fcc phase, but not the hcp Ru phase. This may be explained by leaching of the pure ruthenium catalysts and re-decoration on Pt nanoparticles, or by formation of an amorphous Ru oxide or, less likely, Pt-Ru alloy during operation. However, these structural changes do not seem to significantly affect the cell performance.

Item Type: Article
Erschienen: 2006
Creators: Mazurek, Marian and Benker, Nathalie and Roth, Christina and Fuess, Hartmut
Title: Structural and electrochemical investigation of binary mixtures of carbon-supported Pt and Ru catalysts for PEM fuel cells
Language: English
Abstract:

Commercially available carbon-supported pure Pt and pure Ru catalysts were heat treated in order to modify their individual particle sizes, mixed in a mortar and tested for their suitability as anode catalysts in polymer electrolyte fuel cells (PEMFCs). The procedure chosen for mixing monometallic catalysts should bring more flexibility to the preparation of catalysts, which could thus be easily adjusted to the working conditions. The catalyst mixtures were structurally characterized using a combination of X-ray diffraction (XRD) and transmission electron microscopy (TEM), and indicated an increase in particle size with heat treatment temperature, while the size distribution remained sufficiently narrow. The particle size effect on the resulting activity of the catalyst mixtures was investigated by current-voltage measurements (U/i curves) in single cell fuel cells. A mixture of the as-received platinum and ruthenium gave the best results, which was almost comparable to a commercial Pt-Ru alloy catalyst purchased from E-TEK inc. Only a minor decrease in cell performance was seen during long term operation. Following operation, the X-ray diffraction patterns show reflections of the Pt fcc phase, but not the hcp Ru phase. This may be explained by leaching of the pure ruthenium catalysts and re-decoration on Pt nanoparticles, or by formation of an amorphous Ru oxide or, less likely, Pt-Ru alloy during operation. However, these structural changes do not seem to significantly affect the cell performance.

Journal or Publication Title: Fuel cells
Volume: 6
Number: 3-4
Publisher: WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Uncontrolled Keywords: Electrocatalysts, Fuel Cells, Mixture, Nanoparticles, Non-Alloy, Pt, Ru, TEM, XRD
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Erneuerbare Energien
11 Department of Materials and Earth Sciences > Material Science > Structure Research
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 20 Nov 2008 08:25
Additional Information:

Special Issue: Novel Layer Structures for Fuel Cells

Identification Number: doi:10.1002/fuce.200600012
License: [undefiniert]
Funders: Financial support of the Deutsche Forschungsgemeinschaft (SPP “Neue Schichtstrukturen für Brennstoffzellen”) is gratefully acknowledged., M. Mazurek acknowledges a Graduiertenstipendium des Landes Hessen., The authors thank Prof. H. Wendt for helpful discussions.
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