title: Electronic structures of Pt-Co and Pt-Ru alloys for CO-tolerant anode catalysts in polymer electrolyte fuel cells studied by EC-XPS.
abstract: CO tolerance at pure Pt, Pt-Co, and Pt-Ru alloys was investigated by X-ray photoelectron spectroscopy combined with an electrochemical cell (EC-XPS) in order to discover a hint for designing higher performance anode catalysts. After the electrochemical stabilization and/or CO adsorption, these electrodes were immediately transferred to the XPS chamber without exposure to air to avoid contamination of the surfaces. It was revealed that alloying with Co or Ru modified the electronic structures of Pt atoms, resulting in a positive core level (CL) shift of Pt 4f(7/2) which could weaken the Pt-CO interaction. For the Pt-Co alloy electrode, the Pt 4f(7/2) CL shift remained after the electrochemical stabilization despite Co dissolution and formation of a Pt skin layer. Changes in surface core level shifts (DeltaSCLSs) induced by CO adsorption were evaluated and related to the CO adsorption energy. The values of DeltaSCLS at these alloys were smaller than that of pure Pt, indicating that Ru and Co are effective elements to weaken the bond strength of Pt-CO.
authors.affiliation: Clean Energy Research Center, University of Yamanashi, Takeda 4, Kofu 400-8510, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Wakisaka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mitsui
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Hirose
authors.forename: Katsura
authors.initials: K
authors.lastname: Kawashima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Uchida
authors.forename: Masahiro
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000327:Adsorption; D000465:Algorithms; D000497:Alloys / Q000737:chemistry*; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry*; D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D004573:Electrolytes; D004583:Electrons; D010984:Platinum / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013057:Spectrum Analysis; D013499:Surface Properties
chemical_list: D000497:Alloys; D004573:Electrolytes; D011108:Polymers; D003035:Cobalt; D010984:Platinum; D002248:Carbon Monoxide; D012428:Ruthenium