Search

Your search keyword '"Vorotyntsev, Mikhail A."' showing total 243 results
Start Over Author "Vorotyntsev, Mikhail A."
243 results on '"Vorotyntsev, Mikhail A."'

3. Electrocatalytic properties of manganese and cobalt polyporphine films toward oxygen reduction reaction

Author

Konev, Dmitry V., Istakova, Olga I., Dembinska, Beata, Skunik-Nuckowska, Magdalena, Devillers, Charles H., Heintz, Olivier, Kulesza, Pawel J., and Vorotyntsev, Mikhail A.

Subjects
Condensed Matter - Materials Science
Abstract

Novel member of polymetalloporphines, namely manganese polymetalloporphine of type I (pMnP-I) obtained by ion exchange from magnesium polyporphine of type I (pMgP-I) is reported for the first time and compared to its cobalt analogue (pCoP-I). Both polymer films have been obtained via two-step procedure: demetalation of the pMgP-I electrode film via its exposure to trifluoroacetic acid solution, resulting in formation of the metal-free polyporphine of type I (pH2P-I) followed by electrochemically induced incorporation of Co or Mn ions from the acetonitrile solution of cobalt and manganese perchlorates. A further oxidative transformation of pCoP-I, pMnP-I polymer films has led to the corresponding polyporphines of type II, pCoP-II and pMnP-II, possessing such unique features as condensed polymer structure with a very high density of active sites and high electronic conductivity within a very broad potential range including the one corresponding to the neutral (uncharged) state of the polymer matrix. Both polymers of type II also exhibit interesting electrocatalytic activity toward oxygen electroreduction in aqueous neutral (pH 6.7) and alkaline (pH 13) media which was evaluated under cyclic voltammetric and steady-state conditions. The results demonstrate that the efficiency (regardless of the electrolyte) of both polymetalloporphines is comparable to bare platinum electrode. The effect of annealing of polymer-modified electrodes on their catalytic properties has also been considered.

Published
2018

10. C-C coupling of polymer chains in thin films of oxidized polypyrrole doped by BF4− and PF6− anions: Quantum chemical modeling.

Author

Zyubina, Tatyana S., Zyubin, Alexander S., Istakova, Olga I., Talagaeva, Nataliia V., Vorotyntsev, Mikhail A., and Konev, Dmitry V.

Subjects
CHEMICAL models, COUPLING reactions (Chemistry), POLYPYRROLE, THIN films, POLYMERS, ELECTRODE potential
Abstract

Oligopyrrole-acceptor (BF4 or PF6) complexes, i.e., positively charged oligopyrrole (OPy) clusters with BF4− or PF6− doping anions, represent a model of a charged region of the polymer chain inside a polypyrrole film deposited on the electrode surface via electropolymerization of the pyrrole monomer in a non-aqueous electrolyte containing BF4− or PF6− anions. The ratio of 4 to 1 used in the calculation for the ratio of the monomer units-to-anion numbers has been chosen in accordance with the typical electronic charge of the polymer chain (about + 0.25 per monomer unit) for polypyrrole films on the electrode surface at a potential close to the polymerization one. Interaction between such oligopyrrole complexes inside polymer chains in thin films near the electrode surface is considered. Calculations have been performed for the variants: PBE/PAW, ωB97XD/6-31G(d,p), and M062X/6-311+G(2d,p), taking into account periodic conditions as well as in the cluster approximation. It has been shown that such interactions can lead to the new C–C bond formation under certain conditions. Based on calculations of IR spectra of such systems, manifestation of such structures in the form of an intense peak in the region of 1700–1740 cm−1 has been revealed. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

31. Quantum‐chemical modeling of polypyrrole structure in neutral complexes with electron density acceptors.

Author

Zyubin, Alexander S., Zyubina, Tatyana S., Istakova, Olga I., Talagaeva, Nataliia V., Zolotukhina, Ekaterina V., Vorotyntsev, Mikhail A., and Konev, Dmitry V.

Subjects
POLYPYRROLE, ELECTRON density, ELECTROPHILES, VIBRATIONAL spectra, ION energy, POLYMER structure
Abstract

Quantum chemical approach has been applied for modeling the change in the conformation of the polypyrrole (PPy) chain both in its neutral and positively charged (doped) states due to its interaction with incorporated counterions. Polymer has been modeled by oligopyrrole molecule of 9–15 monomer units. It is shown that it is energetically favorable to reorient the pyrrole rings closest to the anion from trans to cis position. This reorientation leads to the formation of meanders which include 3–5 pyrrole rings per loop. Reduction in the loop size decreases the energy of interaction with the ion while an increase in the loop size reduces the number of attached ionic species accompanied by a slight change in their interaction energy with the PPy chain. The observed effect of polymer chain structuring in the presence of anions is proposed as a possible reason explaining the experimentally recorded broadening of the electroactivity potential region and the conductive state of the polypyrrole film on the electrode surface as a result of multiple repetitions of charge/discharge cycles of the polymer chain. Vibrational spectra of oligopyrrole complexes have been calculated, and prospects for experimental detection of predicted conformational states by IR spectroscopy are assessed. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

42. Redox flow batteries: role in modern electric power industry and comparative characteristics of the main types

Author

Petrov, Mikhail M., primary, Modestov, Alexander D., additional, Konev, Dmitriy V., additional, Antipov, Anatoly E., additional, Loktionov, Pavel A., additional, Pichugov, Roman D., additional, Kartashova, Natalya V., additional, Glazkov, Artem T., additional, Abunaeva, Lilia Z., additional, Andreev, Vladimir N., additional, and Vorotyntsev, Mikhail A., additional

Published
2021
Full Text
View/download PDF

50. Time-difference impedance spectroscopy of growing films containing a single mobile charge carrier, with application to surface films on Li electrodes

Author

Vorotyntsev, Mikhail A., Levi, Mikhael D., Schechter, Alexander, and Aurbach, Doron

Subjects
Spectrum analysis -- Usage, Electrodes -- Electric properties, Lithium compounds -- Electric properties, Chemicals, plastics and rubber industries
Abstract

A new approach to analyze the electrochemical impedance spectroscopy (EIS) data for electrodes covered by passivating surface films that grow in time is reported. The time-difference impedance spectra (DIS), which is the difference between two complex impedance curves, Z(omega, T1)-Z(omega, t2) measured after different period of storage, t1and t2 as a function of frequency provide an useful tool for characterizing the nature of the growing passivating films.

Published
2001

Catalog

Books, media, physical & digital resources
See catalog results