Differential equations were used to analyze the impedance of a spherical electrode at arbitrary equilibrium potential and finite electrode reaction rate. The influence of the indifferent electrolyte and the limits of application of equivalent circuits were discussed.
Ellipsometry was used to study the formation of adsorbed surface films in the gold-peptide-cytochrome c system for different conditions of modification of the gold electrode by dipeptides CysGly and CysGlu. It was shown that reversible redox changes of the modifier films are possible and that oxidation of cytochrome c-containing films is irreversible during cyclic or stepwise polarization of the electrode. On the basis of ellipsometric and earlier electrochemical data, a scheme was proposed for the processes occurring in the test system when using modifier solutions with different pH values.
The review presents experimental and literature data reflecting the developments in a promising version of electrochemical nitration of organic compounds where the electrochemical and chemical step are separated in space and in time. The mechanism of electrochemical generation of the active nitrating species (nitronium cations, dinitrogen pentoxide) was discussed. It was shown in a series of aromatic compounds how the electrochemical step (generation of the nitrating species) and the chemical step (nitration) can be combined.
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Relations were derived which can be used to assess on the basis of models the contribution of the electric double layer to activation energies and preexponential factors of electrode reactions determined experimentally.
The kinetics of copper electrodeposition from Cu(II) solutions containing glycine or alpha-alanine was discussed under the assumption that the rate-determining step in the consecutive transfer of electrons changes on account of destruction of a Cu2O phase layer. Current-voltage curves calculated theoretically with the surface concentrations and established values of the kinetic parameters are in satisfactory agreement with the experimental data. The method of analysis employed does not yield satisfactory results in the Cu/Cu(II), beta-alanine system, where much thicker phase films are formed at the interface.
The optimum conditions for ultrasound-enhanced copper electrodeposition from surfactant-containing acidic sulfate solutions in the channels formed by narrow metallized holes in insulating plates were established in the work. The high rate of copper deposition arises from the mutual effects of electrochemical hydrogen evolution and ultrasonic cavitation at the high surface/volume ratios (150 cm-1) in the holes. This effect was called a cavitational exaltation of the cathodic current, and can be used in hole metallizing technology for hybrid integrated circuits and multilayer printed circuit boards.
Cyclic volammetry was used to study the adsorption and electrochemical reactions of triglycine at a gold electrode. It was shown that the tripeptide is adsorbed in alkaline solutions, while its electrooxidation occurs at high anodic potentials in acidic solutions. It was suggested after a comparison with the electrochemical behavior of glycine and glycylglycine that triglycine interacts with the gold surface through its terminal amino group.
The surface state of Armco iron, 12Kh18N9 steel, and D16 alloy and the adsorption of adamantane and its derivatives were studied at E = -0.8 to +4.0 V by measurements of hardness according to Rehbinder, of contact-potential differences, and of potential decay. At iron and steel, three overlapping electrocapillary curves with E(q=0) of -0.37, +1.25, and +2.85 V (nhe) were detected. It was shown that in the potential range examined, the surface charge changes sign repeatedly, and the work of surface formation is a measure of affinity of the surface for the adsorbed organic substances, as at ideally polarizable and reversible electrodes. A connection was established between adsorption and the quality of electropolishing of the materials examined.
The general features of certain electrosynthetic processes involving organic and inorganic compounds were analyzed. The importance of electrocatalytic factors for selectivity control was discussed in the instance of dimerization and addition reactions during the oxidation of anomalous aromatic carboxylates, in the instance of oxygen and chlorine reactions during the electrolysis of dilute chloride solutions, and in the instance of oxygen evolution and sodium perborate formation during the electrolysis of borate-carbonate solutions. Attention was focused on the state of the electrode surfaces, the influence of additives on the forms of chemisorbed oxygen, and on modifying effects in electrosynthesis. New electrolytes and ways to accelerate the electrochemical production of sodium perborate were suggested. Principles of selectivity control in anodic reactions were formulated.
The kinetic laws of the individual steps of hydrogen transport through palladium membranes were studied and methods developed to accelerate the slow steps. A method was developed to deposit on palladium a strongly adhering, stable, catalytically active coating raising the rate of mass transport across the membrane by more than an order of magnitude.
