Showing papers on "Overpotential published in 1973"
TL;DR: In this paper, the authors measured the overpotential of the Tafel's equation (a,b ) (α, i o respectively) for the current density i (A cm −2 ) and temperature in the range of 15-75°C was measured at γ-MnO 2 and β-PbO 2 electrodes in concentrated water solutions of sodium chloride and perchlorate.
30 citations
TL;DR: In this article, the distribution of the reaction affinity among a constituent step was analyzed for the hydrogen-electrode reaction without assuming a unique rate-determining step (the case of coupled control), and it was shown that reaction affinity may be more or less evenly distributed among the steps and that the over-all rate under strong cathodic polarization obeys a rate expression for the slow discharge mechanism rather than the slow-combination or slow-ion + atom desorption mechanism.
30 citations
TL;DR: In this paper, a model for galvanostatic operation of flooded porous electrodes employing metal/metal salt couples is developed for a single, circular pore configuration which accounts for the effects of differing equivalent volumes of the solid reactants.
Abstract: The galvanostatic operation of flooded porous electrodes employing metal/metal salt couples is analyzed. A model is developed for a single, circular pore configuration which accounts for the effects of differing equivalent volumes of the solid reactants. The model also includes effects of variation in solution properties and effects of complexing of the sparingly soluble salt with the bulk electrolyte anion. The couple in concentrated aqueous potassium hydroxide and the couple in concentrated potassium chloride solutions are considered. Overpotential is computed as a function of time for solid‐ film and solution‐diffusion versions of the model. The solid film model shows a linear overpotential‐time relationship and nearly uniform current distribution. The solution‐diffusion model shows a variety of overpotential‐time curves, based on different physical parameters. In general, anodic failure is caused by blockage of pores or by complete coverage of the metal surface by product crystallites. Cathodic failure is caused by low mass transport which leads to limiting currents in the electrode. The solution‐diffusion model may generate extremely nonuniform current distributions, often with maxima inside the pore. These persistent nonuniform current distributions are important in terms of the analysis of cycling behavior.
24 citations
TL;DR: In this article, a model for the hydrogen-electrode reaction on iron in acidic solution was proposed and the hydrogen pressure equivalent to hydrogen overpotential was formulated for discharge-combination and discharge-ion + atom-desorption routes in general forms.
21 citations
TL;DR: In this paper, the ratio of disperse to compact deposit could be estimated from the results of anodic stripping coulometry, while the bet method rendered information about the specific surface area of the disperse part of the deposit.
19 citations
TL;DR: In this article, copper sulphide layers formed by anodically polarizing copper in a Na2S bath were investigated electrochemically using galvanostatic techniques, and the overpotential measurements indicated sulphide films of low porosity, deficient in Cu+ ions.
19 citations
TL;DR: In this article, the hydrogen overpotential on zinc uniformly alloyed with 500 ppm Cd, Fe, Ca, and Mn, as well as 200 ppm Hg, was measured in at room temperature.
Abstract: Hydrogen overpotential on zinc uniformly alloyed with 500 ppm Cd, Fe, Ca, and Mn, as well as 200 ppm Hg, were measured in at room temperature. Exchange current densities and transfer coefficients for each alloy for the hydrogen evolution process were obtained. Except for Cd, all the other impurities including Hg will cause zinc to be more readily corroded in alkaline medium.
15 citations
TL;DR: On the other hand, on electrodes with high hydrogen overpotential such as amalgamated sinter nickel, the heat of adsorption of hydrogen atom is not sufficiently large to split the hydrazine molecule as discussed by the authors.
12 citations
TL;DR: In this paper, it is proposed that stress-corrosion crack propagation occurs because anodic action concentrated at the crack tip supplies an additional electrochemical energy component to the elastic strain energy or else, by introducing cathodically generated hydrogen, reduces the overall energy required for fracture.
Abstract: It is proposed that stress-corrosion crack propagation occurs because anodic action concentrated at the crack tip supplies an additional electrochemical energy component to the elastic strain energy or else, by introducing cathodically generated hydrogen, reduces the overall energy required for fracture. An energy-balance equation f 1 ( K 2 ) + f 2 ( η ) = P in which K, η, and P denote stress-intensity factor, anodic overpotential, and plastic work of fracture, is briefly discussed in terms of current theories of stresscorrosion cracking.
11 citations
TL;DR: Galvanostatic transients in Cu deposition were found to exhibit maxima and the theoretically predicted dependence of tmax on i agrees with the observed behaviour; similarly, the dependence of η max on i can be quantitatively reproduced.
11 citations
TL;DR: The use of a vitreous carbon electrode as a cathode in the amperostatic coulometric titration of aqueous potassium hydrogen phthalate solution is described and it is shown that 10 mg of thephthalate can be titrated with a precision better than 0.5%.
TL;DR: In this paper, the effect of some sulfur-containing additives was found to reduce the cathode overpotential of copper electrodeposition, and the structure of the deposit at the time of the initial maximum over-potential, and after attaining steady-state condition.
TL;DR: In this article, the kinetics and mechanism of reduction of bivalent metals of the iron group at a mercury dropping electrode are examined, and the effect of pH, organic solvent, structure of the double layer, and adsorption of the depolariser on the half-wave potential and limiting currents of the wave for the reduction of cobalt(II), nickel(II, and iron(II) complexes is described.
Abstract: The kinetics and mechanism of reduction of bivalent metals of the iron group at a mercury dropping electrode are examined. The effect of the pH, organic solvent, structure of the double layer, and adsorption of the depolariser on the half-wave potential and limiting currents of the wave for the reduction of cobalt(II), nickel(II), and iron(II) complexes is described. The role of complex formation in depressing the overpotential for the discharge of these metals is considered in detail. Various viewpoints are presented on the mechanism of formation of the catalytic waves of hydrogen, which appear when doubly-charged ions of these metals and various organic substances are present in the solution simultaneously. There is a bibliography of 93 references.
TL;DR: In this article, a system for fast measurement of the hydrogen-deuterium ratio of the liberated hydrogen isotopes in argon as the sweep gas has been developed and is described in detail.
Abstract: Accurate and fast measurements of electrolytic hydrogen-deuterium separation factors are required to study short-term time effects and the effects of other variables, for example overpotential, before the cathode has suffered irreversible changes such as hydrogen embrittlement A system for fast measurement of the hydrogen-deuterium ratio of the liberated hydrogen isotopes in argon as the sweep gas has been developed and is described in detail Unique features include a modified Cartesian manostat and an automatic Toepler pump in the gas collection system, and an automatic mass spectrometer inlet system whose cycle time is about 4 min Calibration procedures are outlined The accuracy and reproducibility in the H/D ratio are ±1% and ±05% respectively, for the range 075 to 50 mol % deuterium in mixtures containing 0 to 80 vol% argon
TL;DR: In this article, the ratio of disperse to compact deposit could be estimated from the results of anodic stripping coulometry, while the bet method rendered information about the specific surface area of the disperse part of the deposit.
Abstract: Zinc has been electrodeposited from alkaline zincate solutions onto steel substrate and its properties investigated as a function of overpotential of deposition. The ratio of disperse to compact deposit could be estimated from the results of anodic stripping coulometry. Electron microscopy, stereo-scanning electron microscopy and X-ray diffraction have been used to study the morphology, crystal orientation and lattice parameters, while the bet method rendered information about the specific surface area of the disperse part of the deposit. The yield and degree of dispersion of the disperse (dendritic) deposit have been found to increase with overpotential. The lattice parameters indicate residual stress in the compact part of the deposit. In one and the same deposit the orientation of the compact part was found to be while that of the dendrites was or . This selectivity of the two types of growth for particular types of crystal nuclei is explained in terms of a much faster growth on the (1010) or (1120) plane than on the (0001) plane, favoured by the structure of the plane at which continuous formation of new layers is possible by the mechanism of unidimensional nucleation.