Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Volume 87 , Issue 2
Showing 1-7 articles out of 7 articles from the selected issue
  • Kumi NAITO, Kanae IIDA, Kazutake TAKADA
    2019 Volume 87 Issue 2 Pages 114-118
    Published: March 05, 2019
    Released: March 05, 2019
    [Advance publication] Released: November 23, 2018

    The reductive desorption of 2-aminoethanethiol (AET) monolayers formed on a polycrystalline gold electrode has been studied using cyclic voltammetry. Three cathodic peaks were observed and they were assigned to reductive desorption from each small domain of Au(111), (100), and (110) over the polycrystalline surface. The kinetics of adsorption were likely under the condition where the kinetic control and the diffusion control were balanced over the concentration range 5–50 μM (M = mol dm−3), whereas it was described by the kinetic control model at 100 μM. The thermodynamics of adsorption was well-described by the Langmuir isotherm. The saturation surface coverage was found to be 5.3 × 10−10 mol cm−2, which suggested that AET adsorbed lying flat on a polycrystalline gold electrode.

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  • Hiroshi TENMYO, Ryosuke SUGIHARA, Atsushi OHTA, Taisuke ASANO, Taro UE ...
    2019 Volume 87 Issue 2 Pages 119-122
    Published: March 05, 2019
    Released: March 05, 2019

    Two sizes of polyacrylonitrile beads were prepared as precursors of carbon beads by varying the reaction solvent ratio of N,N-dimethylformamide to methanol for dispersion polymerization reaction. The spherical structure of the carbon beads were maintained after carbonization and activation. Charge-discharge tests and AC-impedance analyses revealed that the electric resistance between the particles is low without conducting supplements. In addition, an appropriate pore size brought by the KOH activation of smaller carbon beads lead to a better capacitor performance at high current conditions.

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  • Hiroyuki OKAWA, Hideshi MAKI, Minoru MIZUHATA
    2019 Volume 87 Issue 2 Pages 123-133
    Published: March 05, 2019
    Released: March 05, 2019

    The influence of immersion in a hexaammineruthenium chloride ([Ru(NH3)6]Cl3) aqueous solution on the redox reaction on a polyethyleneimine (PEI) thin film modified with gold nanoparticles (AuNPs) is investigated for the electrochemical analysis of the conjugated reaction area of electronic and electrochemical conduction. The PEI thin film is electrodeposited on a glassy carbon (GC) electrode in an ethylenediamine acetonitrile solution. AuNPs were prepared by Frens’s method and loaded onto the PEI thin film on the GC (GC/PEI) electrode. The redox reaction of [Ru(NH3)6]3+ on AuNPs loads onto a PEI film on a GC (GC/PEI/AuNPs) electrode is observed by cyclic voltammetry and electrochemical impedance spectroscopy. The apparent electron transfer rate constant at a single AuNP, calculated from the charge transfer resistance and AuNP number density, increases during immersion of GC/PEI/AuNPs in the [Ru(NH3)6]3+ solution. It is suggested that the redox reaction occurs not only at the AuNPs by the tunneling effect, but also at the GC electrode due to the ionic transport of [Ru(NH3)6]3+ during the immersion in the [Ru(NH3)6]3+ solution. Care should be taken that the electrochemical reaction is measured as soon as possible when using PEI films before the electrolyte can penetrate the film completely, because the ionic conduction of the [Ru(NH3)6]3+ solution in the PEI thin film cannot be ignored during immersion in the electrolyte solution.

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  • Toshihiro TAKASHIMA, Tomohiro SUZUKI, Hiroshi IRIE
    2019 Volume 87 Issue 2 Pages 134-138
    Published: March 05, 2019
    Released: March 05, 2019

    The bimetallic alloy nanoparticle catalysts composed of Pd and Cu were synthesized for electrochemical reduction of CO2. The effect of the catalyst composition on the CO2 reduction activity and the selectivity was investigated, and at the high Pd/Cu ratio CO2 reduction to formate rather than hydrogen evolution proceeded predominantly. The combination of Pd with Cu also changed the stability of the catalyst. By using the bimetallic catalyst, stable reduction current was obtained in the long-term electrolysis while a monometallic Pd catalyst suffered from deactivation due to poisoning by CO. These improvements are attributable to the electrical interaction between Pd and Cu. The resultant lowering shift of a d-band center reduced binding strength of CO, leading to the achievement of stable reduction of CO2 with a small overpotential.

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