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The role of the steric factors in the electrode reactions occurring on the interface covered by aliphatic alcohols and acids has been investigated, taking as an example the Cd 2+ /Cd(Hg) system. It has been shown that this process takes place inside the inner layer and the activated complex is created by the replacement of r ≠ water molecules from the surface. From studies carried out at surfactant concentrations corresponding to the plateau of the adsorption isotherm the steric factors r ≠ / r i have been determined ( r i is the number of solvent molecules replaced from the surface by one molecule of adsorbed surfactant). By comparison with investigations performed at lower coverages the magnitude of r ≠ and r i has been estimated. The influence of different factors on the experimental value of these parameters has been discussed.

The adsorption of 1,6-hexanediol at the Hg—aqueous solution interface was investigated. The differential capacity, interfacial tension and the zero charge potential were measured. Analysis of the results were carried out both at constant charge and at constant potential. Good congruence with respect to the potential and noncongruence with respect to the charge was found. It was shown that the hexanediol molecules orientate flat against the surface and the adsorption could be described equally well by the Frumkin or Flory—Huggins isotherms. Adsorption parameters for the hexanediol were compared with the literature data on adsorption of ethanediol and 1,4-butanediol. It was concluded that adsorption of diols does not affect the thickness of the inner layer. Thus, this adsorption is well described by the model of two parallel capacitors.

On gold electrodes, anodic deposition layers of NiOOH (3) were formed, reduced to the oxide Ni(OH) 2 (2) and reoxidized. Experiments in the absence or presence of the inhibitor 2-(5-aminopentyl) benzimidazole (PAB) yielded the pure NiOOH (3o) and Ni(OH) 2 (2o) or various NiOOH/PAB-layers with the inhibitor outside (3out), inside (3in) or in the total film (3tot). The formation and transformation of various layers can be distinguished by measurements of the anodic oxide growth i ( t ), the electrode capacity C ( t ) or the redox charge Q of the oxide. For 3tot, the rate of nucleation and oxide growth is retarded by PAB, but the oxide growth takes place by the same mechanism of progressive nucleation as in case of 3o. The redox process is inhibited and the charge Q decreases in presence of PAB with increasing number of cycles. This indicates a mobility of PAB within the film. Protons and hydroxyl ions can move in the film, too, since beneath the NiOOH/PAB layer, Au 2 O 3 can be formed and reduced with a small overvoltage. All layers will be electronically conducting as can be concluded from the high capacity C > 10 μF/cm 2 . XPS measurements verify the presumed distribution of PAB in the film. They show the formation of thick PAB-films ( d > 3 nm) at the oxide surface for 3out and 3tot as well as for the pure gold surface. The high PAB concentration within the film and the low intensity of the O 1S-peak for 3tot indicates the formation of NiOOH/PAB-complexes.