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  • 1995-1999  (3)
  • nanocrystalline alloys  (2)
  • PEM fuel cell
  • Pregnancy
  • Pt–Ru alloy
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 29 (1999), S. 627-635 
    ISSN: 1572-8838
    Keywords: ball-milling ; electrocatalyst ; hydrogen evolution ; leaching ; lixiviation ; nanocrystalline alloys ; sodium chlorate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Ball-milled nanocrystalline Ti3RuFe powders were mixed with 1, 2, 4, 10 and 20 equivalents of Al and the mixtures were milled again for 20 h. The amount of Al atoms dissolved into the B2 structure of Ti3RuFe does not exceed 8–9 at %, the remaining being present as elemental Al into the powder mixture. During a subsequent treatment of the composite powder in alkaline solutions, the elemental Al is leached out, while Al solutes in the B2 structure are not affected. An examination of the surface by scanning electron microscopy reveals that the leached powder has a highly porous surface structure. Surface area measurements performed by BET measurements show that there is a tenfold increase in the effective surface area. Activated electrodes made from these porous materials show a significant decrease of the cathodic overpotential for hydrogen evolution in typical chlorate electrolysis conditions of about 80 mV.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8838
    Keywords: anode ; nanocrystalline ; PEFC ; PEM fuel cell ; Pt–Ru alloy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract High energy ball milling, an industrially amenable technique, has been used to produce CO tolerant unsupported Pt–Ru based catalysts for the oxidation of hydrogen in polymer electrolyte fuel cells. Nanocrystalline Pt0.5–Ru0.5 alloys are easily obtained by ball-milling but their performances as anode catalysts are poor because nanocrystals composing the material aggregate during milling into larger particles. The result is a low specific area material. Improved specific areas were obtained by milling together Pt, Ru and a metal leacheable after the milling step. The best results were obtained by milling Pt, Ru, and Al in a 1:1:8 atomic ratio. After leaching Al, this catalyst (Pt0.5–Ru0.5 (Al4)) displays a specific area of 38 m2g−1. Pt0.5–Ru0.5 (Al4) is a composite catalyst. It consists of two components: (i) small crystallites (∼4 nm) of a Pt–Al solid solution (1–3 Al wt%) of low Ru content, and (ii) larger Ru crystallites. It shows hydrogen oxidation performance and CO tolerance equivalent to those of Pt0.5–Ru0.5 Black from Johnson Matthey, the commercial catalyst which was found to be the most CO tolerant one in this study.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-879X
    Keywords: supported catalyst ; nanocrystalline alloys ; metastable alloys ; ball milling ; mechanical alloying ; surface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The high energy ball-milling technique has been used to produce metastable Ni(Ru) alloys supported on alumina. This catalyst has potential application for the hydrogenation of the C=O bond. The active species are first formed by mechanical alloying pure Ni and Ru powders. The alumina support is ground independently until no structural transformation occurs. Finally, the supersaturated Ni(Ru) powder is milled with the alumina support to produce highly dispersed individual Ni(Ru) nanocrystals on the surface of Al2O3. This supported catalyst has been characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and thermal desorption spectroscopy.
    Type of Medium: Electronic Resource
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