| Project/Area Number |
15560021
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thin film/Surface and interfacial physical properties
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
SAITOU Masatoshi Univ.of the Ryukyus, Engineering, Prof., 工学部, 教授 (00284951)
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| Co-Investigator(Kenkyū-buntansha) |
OSHIKAWA Wataru Univ.of the Ryukyus, Engineering, Asst.Prof., 工学部, 助手 (80224228)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2004: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2003: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | homogeneous charge-transfer reaction / electrochemical impedance / Helmholtz layer / multi-step technique / transient response / step growth / 交換電流密度 / 電気二重層 / 反応速度 / nsec / 核形成 / 活性化エネルギー / 電荷移動反応 / 反応速度定数 |
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| Research Abstract |
(1)Charge transfer reactions in the Helmholtz layer in electrodeposition
Electrochemical impedance spectroscopy measurements under a small alternating current density were performed to make investigations into electrochemical reactions on (110) single-crystalline nickel surfaces in nickel sulfamate electrolyte. The reaction impedance shows a power law of the ac modulation frequency and two exponents for the reaction resistance and reaction capacitance are found to agree with the values predicted by a homogeneous charge-transfer reaction model. In addition, the Nyquist diagrams exhibit the absence of inductive loops. A condition for the existence of inductive loops derived in this study suggests that the electrocrystallization of Ni^<2+> ions may take place in the slow reaction step Ni^<2+>+e^-→Ni^+_<abs> and in the fast reaction step Ni^+_<abs>+e^-→Ni.
(2)Transient process in the Helmholtz layer in electrodeposition
A method is described for the study of the kinetics of electrode reaction
… More
s on the basis of analytical solutions of three transient electrochemical processes comprising the diffusion of ions, charge-transfer reactions and a charging process of an electrochemical double-layer. Multi-pulse currents are applied to a working electrode and the potentials are recorded. The measured potential-time curves agree with those predicted by the analytical solution. The kinetic constant, exchange current density and double-layer capacitance are determined from the measured potential-time curves using the analytical solution.
(3)Surface nucleation and growth in electrodeposition
Voltage-time curves in surface growth on single crystalline nickel electrodes in nickel sulfamate have been measured under a fixed current density with a nanosecond rise-time. The transient voltage-time curves in a two-electrode system exhibit three continuous regions that correspond to the reduction of nickel ions by two-step electrochemical reactions, the crystallization process such as nucleation and growth, and steady state surface growth. The measured voltage-time curves are well consistent with the calculation results predicted by phenomenological equations proposed in this study. Less
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