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The permeation of oxygen at atmospheric pressure through Nafion® 120 and NEOSEPTA® ACH‐45T ion‐exchange membranes was investigated by an electrochemical monitoring technique, which utilizes SPE composite electrodes prepared by an electroless plating method. The oxygen diffusion coefficients were almost the same false(∼10−7cm2·s−1false) for each material, but the oxygen solubility was much higher in Nafion than in NEOSEPTA. The oxygen solubility in NEOSEPTA could be explained in terms of dissolution in the aqueous component of the membrane, but the oxygen solubility in Nafion was too high for such an explanation, and was postulated to involve the role of the polytetrafluoroethylene backbone.

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Correlation of mass transfer with current distribution, for deposition and dissolution of metals, on vertical electrodes, under free convection conditions, is discussed. The equation of mass transfer and the Laplace equation, determining the concentration and potential distributions, respectively, are solved simultaneously. The results explain most features of observed current distributions.

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acid (cf. Table I and Fig. 2) might be explained by the assumption that the change of mechanism in such concentrations takes place at current densities higher than those used in this investigation.At low current densities, the Tafel lines become parallel to the log current density axis at potentials negative with respect to the reversible hydrogen potential. This behavior is similar to that of nickel in acid solutions (15) at low current densities, and is similarly attributed to the dissolution of the cathode.