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1.
Woo-Jin Lee Su-Il Pyun Tae-Hyun Yang Joong-Do Kim Young-Ho Baek Han-Gyu Kim 《Journal of Solid State Electrochemistry》1997,1(2):120-125
Hydrogen transport through a Pd-Ni alloy electrodeposited on a Pd substrate (Pd-Ni/Pd bilayer symmetric electrode) has been
investigated using cyclic voltammetry and a.c. impedance spectroscopy combined with the electrochemical hydrogen permeation
method. The permeation build-up current transients and the measured impedance spectra were analyzed using the time-lag method
for the bilayer electrode and a complex non-linear least squares data-fitting method based upon the derived Faradaic admittance
for the hydrogen absorption into and diffusion through the bilayer electrode under the permeable boundary condition, respectively.
The value of the hydrogen diffusivity in the Pd-Ni layer was lower than that in the Pd layer. Furthermore, the values of the
charge transfer resistance and equilibrium absorption constant for the Pd-Ni/Pd bilayer electrode were higher than those for
the Pd single layer electrode. From the experimental results, the role of the thin Ni(OH)2 film formed on the Pd-Ni layer surface in the hydrogen transport through the Pd-Ni/Pd bilayer electrode is discussed in terms
of its passivating effect and extremely large hydrogen solubility.
Received: 22 January 1997 / Accepted: 15 April 1997 相似文献
2.
In the present work, corrosion resistance of surface-coated galvanized steel was quantitatively determined by an analysis
of the alternating current (AC) impedance spectra measured on the salt-spray-tested specimen. To evaluate the corrosion resistance
of the surface-coated galvanized steel, AC impedance spectroscopy was performed on the salt-spray-tested specimen previously
exposed to salt-sprayed corrosive environment. From the analysis of the impedance spectra, the area fraction transient of
white rust θ
2(t) was theoretically derived from the equivalent circuit equation by using two fitting parameters. The values of the two fitting
parameters were determined by fitting the empirical transient equations to the area fraction of the resin coating layer and
to the total resistance obtained from the impedance spectra measured, respectively. From the analyses of θ
2(t) for four kinds of surface-coated galvanized steels with various resin coating layers, it is indicated that as the values
of the two fitting parameters decrease in the order of CP, GI, OD and OM (commercial trade names) specimens, the corrosion
resistance increases in that order as well. Furthermore, from the quantitative comparison of the two fitting parameters with
the polarization resistance of the upper resin coating layer R
p determined from the potentiodynamic polarization curve, it is suggested that the two fitting parameters decrease in value
as well with increasing R
p. 相似文献
3.
Dong-Won Kim Jung-Ki Park Joon-Sung Bae Su-Il Pyun 《Journal of Polymer Science.Polymer Physics》1996,34(13):2127-2137
Blend-based polymer electrolytes composed of poly(ethylene oxide), poly(oligo[oxyethylene]oxysebacoyl), and lithium salts have been prepared. These polymer electrolytes have been investigated in terms of ionic conductivity, transport number, and interfacial characteristics of the lithium electrode in contact with the polymer electrolyte. The influences of the blend composition, the salt used, and its concentration on the electrochemical behavior were studied. © 1996 John Wiley & Sons, Inc. 相似文献
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The repassivation kinetics of pure aluminium have been explored in aqueous alkaline solutions as functions of applied anodic
potential and pH by using an abrading electrode technique and a rotating disc electrode. The repassivation rate of the abraded
bare surface of pure aluminium increased with increasing applied anodic potential in aqueous alkaline solutions, while it
decreased with increasing pH. These results revealed that the growth rate of the passivating oxide film is enhanced by an
applied electric field, but it is lowered due to the chemical attack by hydroxyl ions. A potentiostatic anodic current decay
transient obtained from the abraded electrode surface showed a constant repassivation rate in neutral and weakly alkaline
solutions. In contrast, in concentrated alkaline solutions it was observed to consist of three stages: a high repassivation
rate in the initial stage due to a high formation rate of the oxide film on the abraded bare surface; a zero value of the
repassivation rate in the second stage due to the dissolution of the oxide film by the attack of OH−; a high repassivation rate in the third stage due to a lowered dissolution rate of the oxide film. The dissolution rate of
the passivating oxide film was observed to depend on the removal rate of aluminate ions from the oxide/solution interface.
Received: 1 April 1998 / Accepted: 3 July 1998 相似文献
9.
The effects of pore fractal characteristics on the kinetics of double-layer charging/discharging on a porous carbon electrode were investigated by using theoretical calculations of potentiostatic current transients (PCTs) and cyclic voltammograms (CVs). Prior to theoretical calculation, it was experimentally evidenced that pore fractality is clearly possessed by the porous carbon electrode. From the analyses of the PCTs and the CVs theoretically calculated at various values of pore fractal dimension dF,pore, inner cutoff length rmin, and outer cutoff length rmax of the pore fractality, it was found that as dF,pore increased, the absolute values of the derivatives of the logarithmic PCTs decreased to 0.5, and the current decayed more slowly with time. The rate capability gamma decreases with increasing dF,pore over the whole scan-rate range, which leads to the lower power density. As rmin increased, the current decayed more rapidly in the later stage of the PCT, which is mainly limited by the smaller pores. On the other hand, as rmax increased, the current decayed more rapidly in the earlier stage of the PCT, which is mainly determined by the larger pores. Moreover, the larger values of rmin and rmax enhance the rate capability gamma as well, but they reduce the double-layer capacitance. The beneficial contribution of the larger pores to the power density competes with the detrimental contribution of those pores to the energy density. 相似文献
10.
This paper contributes to the kinetics of hydrogen transport through the Pd foil electrode in 0.1 mol l–1 NaOH solution during the hydrogen extraction from the foil electrode under the self-discharge and potentiostatic conditions
by the analysis of open-circuit potential and anodic current transients, respectively. The hydrogen oxidation rate calculated
based upon the mixed potential theory just equals the rate of hydrogen self-discharge from the electrode during the OCP transient.
When the electrode surface is subjected even to a constant discharging potential, the hydrogen concentration gradient at the
surface is given by the Butler-Volmer equation combined with the decay in actual potential jump with time below the transition
discharging potential; however, the constant hydrogen concentration condition is satisfied at the surface above this potential.
By taking the hydrogen oxidation rate during the OCP transient and the two constraints during the anodic current transient
as the boundary condition at the surface, the hydrogen concentration profile transients have been derived during the hydrogen
extraction under the self-discharge and potentiostatic conditions, respectively.
Electronic Publication 相似文献