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X-ray absorption studies on alloy formation in different carbon-supported Pt-Ru electrocatalysts

Roth, Christina and Martz, Nathalie and Morlang, Alexander and Theissmann, Ralf and Fuess, Hartmut (2004):
X-ray absorption studies on alloy formation in different carbon-supported Pt-Ru electrocatalysts.
In: Physical chemistry, chemical physics, Royal Society of Chemistry Publishing, pp. 3557-3562, 6, (13), [Article]

Abstract

Carbon-supported Pt–Ru (1 : 1) catalysts were synthesized from aqueous solutions of Pt IV and Ru IV salts by two different reduction methods and in an organic solvent according to a slightly-modified Boennemann synthesis. X-ray absorption spectroscopy was applied to characterize the in-house synthesized catalysts in comparison to a commercial carbon-supported Pt–Ru/C alloy catalyst purchased from E-TEK inc. Significant geometric differences were revealed by the conventional EXAFS analysis which are attributed to differences in particle size and alloy formation. In contrast to the commercial catalyst, which is at least partially alloyed, for the in-house synthesized catalysts a much smaller number of Pt–Ru nearest neighbours has been found pointing either towards a rather inhomogeneous alloy formation or to the formation of ruthenium oxide. These findings are in excellent agreement with the results of the ‘‘Atomic’’ XAFS; the lower the number of Pt–Ru nearest neighbour contributions the higher the R value at which the maximum of the AXAFS feature appears. The R value, however, is supposed to be directly reflective of the d band occupancy which decreases as the degree of alloy formation increases.

Item Type: Article
Erschienen: 2004
Creators: Roth, Christina and Martz, Nathalie and Morlang, Alexander and Theissmann, Ralf and Fuess, Hartmut
Title: X-ray absorption studies on alloy formation in different carbon-supported Pt-Ru electrocatalysts
Language: English
Abstract:

Carbon-supported Pt–Ru (1 : 1) catalysts were synthesized from aqueous solutions of Pt IV and Ru IV salts by two different reduction methods and in an organic solvent according to a slightly-modified Boennemann synthesis. X-ray absorption spectroscopy was applied to characterize the in-house synthesized catalysts in comparison to a commercial carbon-supported Pt–Ru/C alloy catalyst purchased from E-TEK inc. Significant geometric differences were revealed by the conventional EXAFS analysis which are attributed to differences in particle size and alloy formation. In contrast to the commercial catalyst, which is at least partially alloyed, for the in-house synthesized catalysts a much smaller number of Pt–Ru nearest neighbours has been found pointing either towards a rather inhomogeneous alloy formation or to the formation of ruthenium oxide. These findings are in excellent agreement with the results of the ‘‘Atomic’’ XAFS; the lower the number of Pt–Ru nearest neighbour contributions the higher the R value at which the maximum of the AXAFS feature appears. The R value, however, is supposed to be directly reflective of the d band occupancy which decreases as the degree of alloy formation increases.

Journal or Publication Title: Physical chemistry, chemical physics
Volume: 6
Number: 13
Publisher: Royal Society of Chemistry Publishing
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 08:19
License: [undefiniert]
Funders: Financial support from the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie is gratefully acknowledged.
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