title: Effects of composition on structure and activity of PtRu/C catalysts.
abstract: A series of carbon supported PtRu bimetallic catalysts with varying Pt:Ru ratio were prepared and characterised using ex situ and in situ XRD, in situ EXAFS at 0 V vs. RHE, ex situ XPS and monolayer CO stripping voltammetry. Although the catalysts were found to be well mixed/alloyed, with no evidence of unalloyed Ru (oxides) present, the surfaces of the electrocatalyst nanoparticles were found to be enriched with Pt compared to the nominal bulk composition. The methanol oxidation activities of the catalysts were determined in 1.0 mol dm(-3) H2SO4. In agreement with published studies of polycrystalline bulk PtRu alloys the catalyst with a 0.6 surface fraction of Pt was found to give the best methanol oxidation activity at 30 degrees C. However, at 80 degrees C a greater surface fraction of Ru could be tolerated, with some activity at low current densities found for a Pt surface fraction as low as 0.2. The results support the conclusion that a limited amount of methanol dehydrogenation occurs at Ru sites or Ru dominated surface ensembles at 80 degrees C.
authors.affiliation: School of Chemistry, University of Southampton, Highfield, Southampton, UK SO17 1BJ.
authors.forename: Richard J K
authors.initials: RJ
authors.lastname: Wiltshire
authors.forename: Colin R
authors.initials: CR
authors.lastname: King
authors.forename: Abigail
authors.initials: A
authors.lastname: Rose
authors.forename: Peter P
authors.initials: PP
authors.lastname: Wells
authors.forename: Hazel
authors.initials: H
authors.lastname: Davies
authors.forename: Martin P
authors.initials: MP
authors.lastname: Hogarth
authors.forename: David
authors.initials: D
authors.lastname: Thompsett
authors.forename: Brian
authors.initials: B
authors.lastname: Theobald
authors.forename: Fredrick W
authors.initials: FW
authors.lastname: Mosselmans
authors.forename: Mark
authors.initials: M
authors.lastname: Roberts
authors.forename: Andrea E
authors.initials: AE
authors.lastname: Russell