Effect of Surface Segregation on the Methanol Oxidation Reaction in Carbon-Supported Pt−Ru Alloy Nanoparticles

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Abstract

Ru and Pt−Ru (Pt:Ru = 1:1) nanoparticles supported on carbon black were prepared by the borohydride reduction method using oleylamine as a stabilizer in an anhydrous ethanol solvent. We investigated the effect of Pt segregation to the surface of alloy nanoparticles on the methanol oxidation reaction (MOR). As-prepared Pt₁Ru₁/C showed a narrow size distribution and a relatively uniform particle distribution on a carbon support. However, its electrocatalytic activity toward the MOR was poor due to the high surface concentration of Ru. As duration time of heat treatment at 200 °C was increased up to 2 h, the surface composition of Pt atoms was increased without significant particle growth due to thermally induced segregation of Pt atoms, which were revealed by TEM images, X-ray photoelectron spectroscopy (XPS) analysis, changes in the potentials of zero total charge (pztc), and increase in the oxidation charge of “reduced CO₂”. In particular, from the combination of CO adlayer oxidation and “reduced CO₂” oxidation charges, the increased surface concentration of Pt of alloy catalysts was relatively quantified when compared to its as-prepared state. Cyclic voltammograms in 0.1 M HClO₄ solution with 0.5 M methanol showed that Pt₁Ru₁/C annealed for 2 h at 200 °C in a flow of mixture gas of Ar and H₂ (5 vol %) had a less positive onset potential for the MOR. These results demonstrate a definitive contribution from segregation of Pt atoms to the MOR activity.

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This article has been cited by 2 ACS Journal articles (2 most recent appear below).

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  Hierarchical Nanoporous PtFe Alloy with Multimodal Size Distributions and Its Catalytic Performance toward Methanol Electrooxidation

  Caixia Xu, Qian Li, Yunqing Liu, Jinping Wang, and Haoran Geng
  Langmuir2012 28 (3), 1886-1892

  • Hierarchical Nanoporous PtFe Alloy with Multimodal Size Distributions and Its Catalytic Performance toward Methanol Electrooxidation

    Caixia Xu, Qian Li, Yunqing Liu, Jinping Wang, and Haoran Geng
    Langmuir2012 28 (3), 1886-1892

    The hierarchical nanoporous (NP) PtFe alloy with multimodal size distributions is straightforwardly fabricated by means of mild de-alloying of the PtFeAl source alloy. This interesting NP structure consists of interconnected larger ligaments around ...

    Abstract | Full Text HTML | Hi-Res PDF | PDF w/ Links
• 

  Surface Structures and Electrochemical Activities of Pt Overlayers on Ir Nanoparticles

  Kug-Seung Lee, Sung Jong Yoo, Docheon Ahn, Tae-Yeol Jeon, Kwang Hyun Choi, In-Su Park, and Yung-Eun Sung
  Langmuir2011 27 (6), 3128-3137

  • Surface Structures and Electrochemical Activities of Pt Overlayers on Ir Nanoparticles

    Kug-Seung Lee, Sung Jong Yoo, Docheon Ahn, Tae-Yeol Jeon, Kwang Hyun Choi, In-Su Park, and Yung-Eun Sung
    Langmuir2011 27 (6), 3128-3137

    Pt overlayers were deposited on carbon-supported Ir nanoparticles with various coverages. Structural and electrochemical characterizations were performed using transmission electron microscopy (TEM), X-ray diffraction, high-resolution powder diffraction (...

    Abstract | Full Text HTML | Hi-Res PDF | PDF w/ Links

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