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Potential dependence of segregation and surface alloy formation of a Ru modified carbon supported Pt catalyst

DOI: 10.1016/j.electacta.2007.02.023 DOI Help

Authors: A. Rose (University of Southampton, U.K.) , E. Crabb (Department of Chemistry, The Open University, U.K.) , Y. Qian (Department of Chemistry, The Open University, U.K.) , M. Ravikumar (Department of Chemistry, The Open University, U.K.) , P. Wells (Department of Chemistry, The Open University,) , R. Wiltshire (School of Chemistry, University of Southampton, U.K.) , J. Yao (School of Chemistry, University of Southampton, U.K.) , R. Bilsborrow (CLRC Daresbury Laboratory, U.K.) , F. Mosselmans (Diamond Light Source) , A. Russell (School of Chemistry, University of Southampton, U.K.)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Electrochimica Acta , VOL 52 (18) , PAGES 5556 - 5564

State: Published (Approved)
Published: May 2007

Abstract: Ruthenium modified carbon supported platinum catalysts have been shown to have a similar activity towards carbon monoxide oxidation as conventionally prepared bimetallic PtRu alloy catalysts. In this study the effect of the applied electrode potential and potential cycles on the location and oxidation state of the Ru species in such Ru modified Pt/C catalysts was investigated using in situ EXAFS collected at both the Ru K and Pt L3 absorption edges. The as prepared catalyst was found to consist of a Pt core with a Ru oxy/hydroxide shell. The potential dependent data indicated alloying to form a PtRu phase at 0.05 V versus RHE and subsequent dealloying to return to the Ru oxy/hydroxide decorated Pt surface at potentials greater than 0.7 V. The Ru–O distances obtained indicate that both Ru3+ and Ru4+ species are present on the surface of the Pt particles at oxidising potentials; the former is characteristic of the as prepared Ru modified Pt/C catalyst and following extensive periods at potentials above 0.7 V and the latter of the Ru oxide species on the PtRu alloy.

Journal Keywords: Ruthenium; Platinum; Fuel Cell Catalyst; EXAFS;Co Oxidation

Subject Areas: Chemistry

Facility: Daresbury Laboratory