Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Volume 67 , Issue 12
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Visions
Headline
  • Kohei UOSAKI
    1999 Volume 67 Issue 12 Pages 1105-1113
    Published: December 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    A self-assembly (SA) technique has been very widely used to construct ordered molecular layers of various functionalities on a solid substrate and self-assembled monolayers (SAMs) of alkylthiols on gold have been the most well studied system. In this article, the SA process and typical functionalities of the SAMs of thiol derivatives are described mainly based on the results obtained in our group over the last 10 years. The structure and mass transport during the self-assembly process of the thiol derivatives on Au(111) were investigated by quartz crystal microbalance (QCM) measurement, polarization modulation Fourier transform infrared spectroscopy (PM-FTIR) and scanning tunneling microscopy (STM). The electrochemical characteristics and related mass transport and structural changes of the SAMs were carefully examined. The SAMs with novel functions such as uni-directional electron transfer, electrochemically generated chemiluminescence (ECL), visible light induced uphill electron transfer, and electrochemically controllable SHG activity were constructed. Finally, future prospects are presented.

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Communications
Technical Papers
  • Ruxandra VIDU, Shigeta HARA
    1999 Volume 67 Issue 12 Pages 1240-1242
    Published: December 05, 1999
    Released: November 15, 2019
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    The formation and growth of thin alloy film at underpotentials during the electrodeposition of Cd on Au(100) in 50 mM H2SO4 + 1 mM CdSO4 solution was study at room temperature by in situ atomic force microscopy (EC-AFM) and polarization experiments. It was found that the overall process at Au(100)/Cd2+ interface can not be described by a simple function of time. Estimation of the diffusion coefficients suggested that the relaxation processes at metal/electrolyte interface affect the alloy formation.

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  • Keiji WATANABE, Masatoshi SAKAIRI, Hideaki TAKAHASHI, Katsumi TAKAHIRO ...
    1999 Volume 67 Issue 12 Pages 1243-1248
    Published: December 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    Aluminum specimens were covered with zirconium oxide films by sol-gel dip coating at Th = 573 and 873 K, and then anodized galvanostatically in a neutral borate solution. The time-variation in the anode potential during anodizing was monitored, and the structure of anodic oxide films was examined by TEM, EDX, and RBS. During anodizing of specimens coated with ZrO2 at Th = 573 K, the anode potential, Ea, increased linearly with time, ta, and the slope of the Ea vs. ta curve increased with increasing the number of sol-gel coatings. An anodic oxide film, which was composed of an inner Al2O3 layer and an outer Al-Zr composite oxide layer, grew at the interface between the ZrO2 layer and metal substrate during anodizing. The thickness of the inner layer increased with ta, whereas the thickness of the outer layer showed a maximum before decreasing with ta. Specimens coated with ZrO2 at Th = 873 K showed Ea-jumps between 40 and 110 V just after the commencement of anodizing, and then a slow Ea increase. An anodic oxide film composed of a single layer of Al2O3, formed beneath the ZrO2 layer during anodizing. The mechanism of the formation of anodic oxide films on aluminum coated with ZrO2 films is discussed in terms of ion transport across the anodic oxide film.

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  • Masami TAGUCHI, Kazunori KANDA
    1999 Volume 67 Issue 12 Pages 1249-1253
    Published: December 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    In order to develop all solid state electrochemical cells, thin film PbO2/PbO/Pb solid cells were produced. All the constituents were systematically deposited on a glass substrate by reactive sputtering and vacuum evaporation. The discharge properties of the solid cells were improved by the addition of a uni-valent impurity such as sodium or potassium to the PbO electrolyte; the electromotive force of the solid cell using PbO-3.13 mass % Na2CO3 as the electrolyte reached 69% of the theoretical value during discharge. On the other hand, the presence of a tri-valent impurity such as antimony or bismuth in the electrolyte decreased the electromotive force. The electrolytes with the uni-valent impurities had a lower electronic conductivity compared with the impurity-free PbO, while the electrolytes with the tri-valent impurities had a higher one. These results were interpreted by a point defect model of oxygen ion vacancies which are the dominant defects in the PbO electrolyte; the uni-valent impurities increase the concentration of the vacancies to improve the ionic conductivity of the electrolyte. Also, the discharge reactions at both interfaces of PbO2/PbO and PbO/Pb were determined by X-ray photoelectron spectroscopy.

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  • Susumu KUWABATA, Hiroshi KANEMOTO, Daisuke OYAMATSU, Hiroshi YONEYAMA
    1999 Volume 67 Issue 12 Pages 1254-1257
    Published: December 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    In our previous studies, it was found that underpotential deposition (UPD) of Ag or Cu on an Au electrode coated with a self-assembled monolayer (SAM) of alkanethiol enhanced stability of the monolayer against its reductive desorption in an alkaline solution. Degree of the stabilization effect was higher for the Cu UPD than the Ag UPD. By utilizing such the behavior, a new method to induce partial desorption of the SAM has been developed in this study. This method enables easy changes in the ratio of thiol-free areas, and numerous pores can be generated in the monolayer when the ratio of the thiol-free areas was small.

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  • Kengo SHIMANOE, Tetsuya KIDA, Hideki KAWATE, Norio MIURA, Noboru YAMAZ ...
    1999 Volume 67 Issue 12 Pages 1258-1261
    Published: December 05, 1999
    Released: November 15, 2019
    JOURNALS OPEN ACCESS

    Potentiometric devices for which a disc of NASICON (Na+ conductor, Na3Zr2Si2PO12) was attached with an auxiliary phase of Na2CO3 (I) or Na2CO3-BaCO3 (2 : 3 in molar ratio) (II) were investigated for CO2 sensing properties and the structure of hetero-junctions involved. SEM observation combined with EPMA analysis indicated that, for device (I), a corrosion layer (20-30 µm) rich in Na content was formed inside NASICON. The corrosion layer was estimated to consist mainly of Na2ZrSiO5 and Na2ZrO3 from separate experiments using powder samples. For device (II), in contrast, such a corrosion layer was hardly formed between the carbonate and NASICON. This difference in junction structure could account well for the difference in CO2 sensing capability at lower temperature between the devices.

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