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The formation of bimetallic composites by the electrochemical codeposition of Fe(III)Cl-5,10,15,20-tetrakis(4-aminophenyl)porphyrin and Mn(III)Cl-5,10,15,20-tetrakis(4-aminophenyl)porphyrin was studied. The composites were obtained by the superoxide-assisted electrochemical deposition from mixed solutions of DMSO with equal concentrations of porphyrins. The spectral analysis of the composites showed that they were enriched in the Mn complexes of porphyrin. A comparative analysis of the morphology, electroactive surface area, and specific features of oxygen electroreduction on the films of individual porphyrins and the composites was carried out. It was shown that the catalytic activity of bimetallic composite was higher than that of the materials based on the individual metal complexes. [ABSTRACT FROM AUTHOR]

This work confirms formation of surface films of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (H2T(4-NH2Ph)P) in dimethylsulfoxide in the potential range of oxygen electroreduction. Kinetics of variation of faradaic currents and of the interface characteristics are studied at the working electrode potentials of +0.5 V (porphyrin electrooxidation), –0.9 V (oxygen electroreduction), and –1.25 V (coreduction of porphyrin and oxygen). It is shown that the working electrode surface is passivated at the potential of +0.5 V and faradaic currents decrease fast. At the potentials of –0.9 and –1.25 V, the working electrode surface passivation is less pronounced. As shown by analysis of electrode impedance spectra, a film is formed on the electrode surface under electroreduction conditions (–0.9 and –1.25 V), as opposed to electrooxidation conditions (+0.5 V). Charge transport through this film can be characterized by modeling the interface impedance. The kinetics of variation of the interface parameters allow estimating the stage mechanism of film formation and restructuring of the formed layer. [ABSTRACT FROM AUTHOR]

The electrode impedance spectroscopy technique was used to study the process of formation of a conducting polyporphyrin film on a Pt electrode from a 10 M solution of tetrakis( p-aminophenyl)porphin in dichloromethane. An equivalent circuit is suggested for simulation of interface impedance in a wide range of working electrode potentials. It is shown that regions with a different mechanism of film formation are observed at an increase in potential from 0.0 to +1.0 V. The kinetics of film formation are studied at the potentials of +0.40, +0.60, and +0.80 V. It is found that good agreement is observed between the model and experimental data when the growing film is simulated using a Warburg element with a finite diffusion length. Conductivity and the diffusion coefficient of charge carriers in it are estimated on the basis of the suggested model for a film obtained at the potential of +0.40 V. It is shown that conductivity of a polyporphyrin film grows by more than an order of magnitude at an increase in deposition potential from +0.40 to +0.80 V. [ABSTRACT FROM AUTHOR]

The system Cu/HO-CHOH-CuSO was studied in a wide range of organic component concentrations by the impedance spectroscopy method. In the studied range of ethanol concentrations the diffusion of ions to an electrode is the limiting stage of the electrode process. An increase in the ethanol concentration results in a decrease in the double electrical layer capacity, which is caused by a change in the double electrical layer structure at the electrode-solution boundary. [ABSTRACT FROM AUTHOR]

The process of electroreduction of copper from aqueous ethanol solutions of copper sulfate on a copper electrode is studied using the polarization and impedance techniques. It is shown that, at the working electrode potentials in a range of −0.6 to −0.8 V, the rate-limiting step of the process is the diffusion of copper ions to the electrode's surface. The diffusion coefficient of copper ions at an ethanol concentration of about 0.08 m. f. takes the minimum value due to the restructuring of the near-electrode layer at the given concentration of alcohol. [ABSTRACT FROM AUTHOR]

By the method of impedance spectroscopy the properties of the phase boundary of Cu|H2O + i-C3H7OH + CuSO4 system were investigated. The impedance hodographs were obtained, in the form of circles with displaced centers. The capacity values of electrical double layer, exchange currents, and resistance of the electrolyte solution depending on the mole fraction of 2-propanol were determined. The role of organic component in the formation of the electrical double layer in the studied system is elucidated. [ABSTRACT FROM AUTHOR]

A magnetic field and temperature was shown to affect disperse composition, electrophoretic behavior, and aggregation stability of synthesized magnetite particles. When synthesis proceeds, a process of the nucleation of ultramicroscopic Fe3O4 particles prevails over a process of their aggregation. Here an electrostatic factor of stability of magnetite suspension plays an important role. An application of the magnetic field decreases the aggregation stability and increases the sedimentation rate of product particles. [ABSTRACT FROM AUTHOR]

A magnetic field and temperature was shown to affect disperse composition, electrophoretic behavior, and aggregation stability of synthesized magnetite particles. When synthesis proceeds, a process of the nucleation of ultramicroscopic Fe3O4 particles prevails over a process of their aggregation. Here an electrostatic factor of stability of magnetite suspension plays an important role. An application of the magnetic field decreases the aggregation stability and increases the sedimentation rate of product particles. [ABSTRACT FROM AUTHOR]

This review is devoted to porphyrin-based film materials. Various technological and scientific applications of ones are close to surface and interface related phenomena. In the part I of review the following topics are discussed the recent progress in field of submonolayers, monolayers and multilayers films on the vapor-solid interfaces, including results on (i) conformational behavior of adsorbed molecules, (ii) aggregation and surface phases formation, (iii) on-surface coordination networks, and (iv) on-surface chemical reactions. The examples of combined approaches to developing materials and porphyrin-based film materials application are also presented., (Copyright © 2018 Elsevier B.V. All rights reserved.)