Experimental and theoretical cyclic voltammograms for electronically conducting polypyrrole film are obtained from the identical conditions and compared to each other to characterize electrochemical behavior of the polymer. A comparison of the simulated and experimental cyclic voltammograms shows quantitative agreement. The profiles of the dependent variables show that the switching process is governed by the availability of the counterion to the polypyrrole electrode and the amount of electroactive sites. Sensitivity analysis shows that the double layer effects have more influence in the cyclic voltammograms than the electrokinetic effects.

The adsorption and absorption of chloride on iron in borate buffer solution have been studied using a radiotracer technique. The two processes are clearly distinguishable by their different time constants, ∼ 1 min for adsorption and ∼ 1h for absorption. The adsorpton of chloride on bare iron and passive layer surfaces follows the Tempkin type of isotherm. The free energy of adsorption of chloride on passive layer is significantly higher than that on bare iron. Partial charge transfer between adsorbed chloride ion and Fe2+ and/or Fe3+ on the passive surface has been proposed to account for this difference. The “saturation” coverage of chloride on passive layer varies with concentration and attains a value of 0.8 at higher concentrations. The absorption of chloride into the passive layer starts at about −0.1 V/NHE, followed by a linear increase with the potential. The steady‐state value of absorption of chloride at the breakdown potential varies with concentration of chloride in the solution and breakdown potential. The maximum value of absorption before breakdown occurs is θ=2.5 .

Ni‐P alloys were prepared by electrodeposition under different conditions on a rotating disk electrode. A variety of alloys were prepared ranging from Ni‐15P to Ni‐25P. An indirect reduction of species in solution involving several steps appears to be favored over the direct reduction at the electrode based on the low P content in the alloy. Energy dispersion x‐ray microanalysis was used to determine composition of the alloy. Transmission electron microscopy and x‐ray diffraction corroborated the amorphous nature of the structure. The physical and chemical homogeneity of the metallic glasses produced electrochemically is substantiated by the absence of electrochemical localized attack. Thus, a passivation mechanism is proposed which explains the formation of a broad range passive film in alkaline medium and also explains the narrow range of the passive film in acid and neutral media.

This paper reports an investigation of the adsorption of hydrogen on iron during the hydrogen evolution reaction. The solution pH was 8.4. The investigation was carried out by means of FTIR spectroscopy. Fe-H vibrations were identified at 2060 and 980 cm-'; and were compared with the values of estimates for stretching and bending vibrations in Fe-H, respectively. The peak intensities varied with electrode potential. Assuming that the area under the peak at 2060 cm -~ is proportional to the hydrogen coverage, 0s, on iron, a slope of F/6RT was obtained for the plot of 0 vs. "q where ~ is the overpotential. Corresponding experiments with D~O showed peaks which are relatable to those for hydrogen in an expected manner. An indirect estimate of the OH value suggested this to be about 0.3 at -0.9V. The results are consistent with a slow discharge-atomic combination route for hydrogen evolution.

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