Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Volume 71 , Issue 8
Showing 1-14 articles out of 14 articles from the selected issue
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  • Kotaro OGURA
    2003 Volume 71 Issue 8 Pages 676-680
    Published: August 05, 2003
    Released: August 30, 2019
    JOURNALS OPEN ACCESS

    A new electrolysis system has been developed for the efficient reduction of carbon dioxide in which CO2 is selectively reduced to ethylene by the electrolysis at the three-phase (gas/liquid/solid) interface on a CuCl-confined Cu-mesh electrode. In this system, CO2 is supplied to the electrode surface from gas phase, and a high concentration of CO2 can be maintained during the electrolysis irrespective of the solubility of CO2 to solution. Maximum faradaic efficiency (about 70%) for C2H4 was obtained at −1.8V vs Ag/ AgCl, and the selectivity estimated on the basis of carbon content was about 75%. The selective reduction of CO2 to ethylene was found to be caused by the immobilized CuCl which operates as a heterogeneous catalyst by offering adsorption sites for CO and methylene radicals.

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Articles
  • Katsuhiko SHINYAMA, Yoshifumi MAGARI, Atsuhiro FUNAHASHI, Toshiyuki NO ...
    2003 Volume 71 Issue 8 Pages 686-690
    Published: August 05, 2003
    Released: August 30, 2019
    JOURNALS OPEN ACCESS

    The high-temperature characteristics of sintered nickel positive electrodes for alkaline storage batteries such as nickel-metal hydride batteries and nickel-cadmium batteries were investigated. Generally, the discharge capacity of an alkaline storage battery charged at high temperature is smaller than that charged at room temperature due to the oxygen evolution reaction. In order to enhance high-temperature characteristics, we coated sintered nickel positive electrodes with yttrium hydroxide, calcium hydroxide or cobalt hydroxide. The high-temperature characteristics of the sintered nickel positive electrodes coated with yttrium hydroxide and calcium hydroxide by immersing them in sodium hydroxide solution after immersing in nitrate solution were greatly enhanced because of the increased oxygen overvoltage.

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  • MoonYup JANG, YoungSun PARK, Yohtaro YAMAZAKI
    2003 Volume 71 Issue 8 Pages 691-694
    Published: August 05, 2003
    Released: August 30, 2019
    JOURNALS OPEN ACCESS

    Sulfonated cerium phenylphosphonate, Ce (O3PC6H4SO3H)2·3.86H2O, was synthesized to prepare thin film membrane having increased thermal stability, hydrophilicity, and improved methanol crossover resistance. The compound was characterized by X-ray diffraction, FTIR, and TG- DTA analysis. The initial weight of TGA curve extends to 180°C and results from loss of interlayer water in the amount of 10.2% or 3.86 moles. AC conductivity measurements were in-vestigated in the range of 25-200°C as a function of relative humidity. With increasing relative humidity in the range 40-100% at 175°C, the conductivity rises by 1 order of magnitude up to about 0.026 Scm−1. The activation energy of conductivity yields 0.21 eV for the 100-175°C region under PH2O/PS= 1.

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  • Shunzo SUEMATSU, Takashi ISHLKAWA, Mika HANADA, Hideaki TAKENOUCHI, Ka ...
    2003 Volume 71 Issue 8 Pages 695-702
    Published: August 05, 2003
    Released: August 30, 2019
    JOURNALS OPEN ACCESS

    Polyindole derivatives with a series of electron-withdrawing groups (-F, -Cl, -Br, -CN, -NO2) substituted via 3-, 5-, and 6-positions have been investigated for their electrochemistry and the capabilities as electrode materials for supercapacitors (redox capacitors) or proton batteries. All of the 5- and 6-substituted indoles were successfully electropolymerized to give thin electroactive films with varieties of electroactivities and molecular weights. Among the poly(5- and 6-indole)s, a poly(5-cyanoindole) exhibited the most positive E0'(1.15 V vs. Ag/ AgCl), the highest specific capacity (53 Ah kg-1) and an excellent cycleability over several thousand cycles. On the other hands, the 3-substituted indoles did not give any electroactive polymeric products. The relationship between the apparent formal potential (E0) and Hammet constants (σ) for the electroactive poly(substituted indole)s was also investigated.

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  • Yuka ITO, Yasushi IDEMOTO, Yuka TSUNODA, Nobuyuki KOURA
    2003 Volume 71 Issue 8 Pages 703-709
    Published: August 05, 2003
    Released: August 30, 2019
    JOURNALS OPEN ACCESS

    We have been studied the relation between crystal structures, electronic structures, thermodynamic stability and cycle performances of LiMn2-xZnxO4(x=0.05, 0.10) as cathode active materials for 4 V class Li secondary battery. The crystal structures are Fd-3m and the bond lengths of (Mn, Zn)-O of LiMn1. 9Zn0.lO4 decrease in comparison with that of LiMn2O4. The cycle performance improves on increasing Zn content. The heat of dissolution of the samples was measured. These samples are more stable thermodynamically with increasing Zn content. Moreover, we calculated the net charge of each atom, the bond overlap population of Li-O, Mn-O, Zn-O, the density of states, and the electron density of Li Mn1.75M0.25O4 (M=Mn, Zn) using first principles calculation by DV-Xαmethod. Li ionicity always keeps high and the covalent bonding of Mn-O in the octahedron of LiMn1.75Zn0.25O4 is stronger than that of LiMn2O4.

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