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  • 1995-1999  (5)
  • ROSETTA  (2)
  • sodium chlorate  (2)
  • PEFC
  • 1
    Electronic Resource
    Electronic Resource
    Comparative study of nanocrystalline Ti2RuFe and Ti2RuFeO2 electrocatalysts for hydrogen evolution in long-term chlorate electrolysis conditions (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 551-560 
    Details
    ISSN: 1572-8838
    Keywords: ball-milling ; electrocatalyst ; hydrogen evolution ; nanocrystalline alloy ; sodium chlorate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Ti2RuFe and Ti2RuFeO2 nanocrystalline alloys were prepared by high energy ball-milling and used as cathodes for the hydrogen evolution reaction (HER) in the process of sodium chlorate synthesis. Ti2RuFe is almost single phase with the B2 structure. In contrast, Ti2RuFeO2 is made of a mixture of Ti2RuFe and TiOx phases. Tests in chlorate electrolysis conditions did not show any sign of degradation of Ti2RuFeO2 over a 300 h period, while Ti2RuFe breaks down after less than 100 h. The degradation of Ti2RuFe occurs because of hydrogen absorption and desorption during alternating hydrogen discharge and open-circuit conditions. Various hypotheses to explain the increase stability of the O containing alloy are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026441532352
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Large specific surface area nanocrystalline Ti–Ru–Fe cathode materials for sodium chlorate (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 627-635 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1026408502373
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    High energy ball-milled Pt and Pt–Ru catalysts for polymer electrolyte fuel cells and their tolerance to CO (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 951-960 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1003505123872
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Rosetta Goes to Comet Wirtanen (1999)
    Springer
    Space science reviews 90 (1999), S. 313-319 
    Details
    ISSN: 1572-9672
    Keywords: ROSETTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The International Rosetta Mission, approved by the Science Programme Committee of the European Space Agency as the Planetary Cornerstone Mission in ESA's long-term programme Horizon 2000, will rendezvous in 2011 with Comet 46P/Wirtanen close to its aphelion and will study the nucleus and the evolution of the coma for almost two years until it reaches perihelion. In addition to the investigations performed by the scientific instruments on board the orbiter, a Surface Science Package (Rosetta Lander) will be deployed onto the surface of the nucleus early during the near-nucleus study phase. On its way to Comet 46P/Wirtanen, Rosetta will fly by and study the two asteroids 4979 Otawara and 140 Siwa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005231006010
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  • 5
    Electronic Resource
    Electronic Resource
    Coma Composition and Evolution of Rosetta Target Comet 46P/Wirtanen (1999)
    Springer
    Space science reviews 90 (1999), S. 321-328 
    Details
    ISSN: 1572-9672
    Keywords: ROSETTA ; Space Mission Target Comets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Comet 46P/Wirtanen is the target comet of the ROSETTA mission. Here, we give an overview of the information currently available on this comet from remote-sensing observations. Main emphasis is put on the description of the coma in terms of morphology, composition and evolution. We also summarize the current knowledge of the basic properties of the nucleus, in particular its size and rotational properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005235122848
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    Paper (German National Licenses)
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