Hydrogen-bromate flow battery: can one reach both high bromate utilization and specific power? / A. D. Modestov, D. V. Konev, A. E. Antipov, M. A. Vorotyntsev // Journal of Solid State Electrochemistry. — 2019. — Vol. 23, no. 11. — P. 3075–3088. Hydrogen-bromate flow battery is a promising hybrid current source for air-deficient environment that functions by electrocatalyzed reactions of hydrogen oxidation and aqueous LiBrO3 reduction. The flow cell consists of porous carbonaceous cathode, platinum catalyzed hydrogen oxidation gas diffusion anode, and separating proton exchange membrane. Performance of the hydrogen-bromate flow battery single cell has been optimized by varying the catholyte feed rate, LiBrO3 concentration in catholyte, hydrogen pressure, membrane thickness, amount of porous carbon at cathode, and Pt loading at anode. Shape of the I-V curve is characterized by a sharp maximum of current, which indicates passivation of one of the electrodes. Combination of conventional reference electrode and home-made thin-film Luggin capillary has been used to monitor separately the polarizations of both flow cell electrodes. Poisoning of platinum hydrogen oxidation electrocatalyst by bromine species, which permeated the membrane, is shown as a major source of performance losses of hydrogen-bromate flow battery at high power density. Hypothesis supported by experiments claims that the degree of the platinum electrocatalyst poisoning is determined by the balance between the rates of the bromine species supply to anode and their removal by liquid water that permeates the membrane. Use of thinner proton exchange membrane and thinner carbonaceous cathode is a prerequisite to achieving high power density of the cell at high current efficiency of the cathode process. At 40 oC, area-specific power reaches 0.74 W cm−2 at the level of catholyte utilization equal to 0.93. [ DOI ]
Vorotyntsev M. A., Rubashkin A. A. Uniformity ansatz for inverse dielectric function of spatially restricted nonlocal polar medium as a novel approach for calculation of electric characteristics of ion–solvent system // Chemical Physics. — 2019. — Vol. 521. — P. 14–24. Till now, calculation of the electrostatic potential distribution and other electric properties of a nonlocal polar medium occupying a restricted spatial region has been carried out within the framework of two different approaches. One of them (which may be called “unrestricted medium approximation”, UMA) disregards the existence of “external region” (where dielectric properties are different from those of the medium), i.e. it assumes that the medium occupies the whole space so that its nonlocal dielectric properties are everywhere identical to those of the bulk medium while the charges (sources of the electric field) are considered as immersed inside the medium, without creating cavities or modifying its dielectric properties. Another approach (usually called “dielectric approximation”, DA) takes into account the difference of dielectric properties between the region occupied by the medium, V, and an “external” region; as for the nonlocal dielectric function inside region V it is assumed to be identical to that of the bulk medium, even for its spatial points near the boundary of the region. The actual study has proposed a novel general procedure (called IDA) for solving the same problem. Similar to the DA one, it also takes into account the difference of dielectric properties in region V and external region(s). However, a different background relation (“uniformity ansatz”) is assumed for dielectric properties of the spatially restricted polar medium: its correlation function of polarization fluctuations has the same form (identical to that for the unrestricted medium) in all points inside spatial region V, even in the vicinity of its boundary. The same property is automatically fulfilled for the inverse dielectric function of the medium inside region V. For several important geometries of the system (e.g. half-space, spherical or cylindrical cavity, etc.) thus defined “the inverse dielectric approach” (IDA) results in simple analytical expressions for the potential and electric field distributions for any nonlocal dielectric function of the bulk polar medium as well as for any distribution of “external charges” (satisfying to the corresponding symmetry conditions). As the first application, the IDA approach has been used for analysis of the electric field and potential distributions for the spherically symmetrical system where a cavity (imitating a “solute ion”) is surrounded by a nonlocal dielectric medium (“polar solvent”). Analytical expressions for these characteristics as well as for the electrostatic contribution to the solvation energy have been derived for any spherically symmetrical distribution of the ionic charge (which may be located in the general case both inside the cavity and outside this region) and for any dielectric responses both inside the cavity and of the polar medium outside the cavity. These results are in perfect agreement with the general principles that both the potential distribution outside the cavity and the ion solvation energy are determined only by the total ionic charge inside the cavity while they are independent of the particular charge distribution in this region. Effects due to the ionic charge penetration into the polar medium are also analyzed. Results for the potential distribution and solvation energy are compared for the novel IDA approach with those for the UMA and for the DA procedures. Conclusion on substantial advantages of the IDA method has been made. [ DOI ]
ТЕОРЕТИЧЕСКИЙ АНАЛИЗ ИЗМЕНЕНИЯ СОСТАВА РАСТВОРА ПРИ АНОДНОМ ЭЛЕКТРОЛИЗЕ БРОМИДА / М. М. Петров, Д. В. Конев, А. Е. Антипов и др. // Электрохимия. — 2019. — Т. 55, № 11. — С. 1307–1317. [ DOI ]
Эволюция состава анолита при окислительном электролизе сернокислого раствора бромида натрия / М. М. Петров, П. А. Локтионов, Д. В. Конев и др. // Электрохимия. — 2019. — Т. 55. — С. 95–105. [ DOI ]
Эффективность процесса электрополимеризации пиррола в различных условиях / О. И. Истакова, Д. В. Конев, Т. О. Медведева и др. // Электрохимия. — 2019. — Т. 55. — С. 85–94. [ DOI ]
A hydrogen-bromate flow battery for air-deficient environments / A. D. Modestov, D. V. Konev, O. V. Tripachev et al. // ENERGY TECHNOLOGY. — 2018. — Vol. 6, no. 2. — P. 242–245. [ DOI ]
Vorotyntsev M. A., Rubashkin A. A., Antipov A. E. A new approach in the theory of spatially-restricted nonlocal dielectric media // Russian Journal of Electrochemistry. — 2018. — Vol. 54, no. 11. — P. 879–885. [ DOI ]
Antipov A. E., Vorotyntsev M. A. Bromate anion reduction at rotating disk electrode in steady state under excess of protons: Numerical solution of the convective diffusion equations at equal diffusion coefficients of components // Russian Journal of Electrochemistry. — 2018. — Vol. 54, no. 1. — P. 62–69. [ DOI ]
Bromate reaction on a rotating disc electrode: A new method of obtaining approximate analytical solutions for stationary regime / M. A. Vorotyntsev, A. E. Antipov, M. M. Petrov et al. // Doklady Chemistry. — 2018. — Vol. 483, no. 1. — P. 256–260. [ DOI ]
Vorotyntsev M. A., Antipov A. E. Bromate electroreduction from acidic solution at rotating disc electrode. theoretical study of the steady-state convective-diffusion transport for excess of bromate ions compared to protons // Electrochimica Acta. — 2018. — Vol. 261. — P. 113–126. [ DOI ]
Bromate electroreduction from sulfuric acid solution at rotating disk electrode: Experimental study / A. D. Modestov, D. V. Konev, A. E. Antipov et al. // Electrochimica Acta. — 2018. — Vol. 259, no. 1. — P. 655–663. Our recent theoretical analysis of the bromate reduction from acidic media at rotating disk electrode (RDE) under steady-state conditions gave astonishing predictions for the current at the plateau of the voltammogram (called “the maximal current”, jmax) which deviated cardinally from those for the previously known mechanisms of electrochemical processes. Because of the non-electroactivity of the bromate anion itself, its transformation (without an added catalyst) can only take place owing to the redox cycle composed of the rapid reduction of bromine species (which are always present in low amounts inside strongly acidic solutions of bromates) into bromide ions at the electrode and of the comproportionation reaction between bromate and bromide ions inside the solution phase which regenerates bromine molecules. According to this theory, owing to the autocatalytic features of this mechanism the dependence of the maximal current density, jmax, on the RDE revolution frequency, f, is complicated. In particular, it includes a range of relatively low frequencies where the maximal current can exceed the bromate diffusion-limited one, even for tracer amounts of bromine in the bulk solution. Another surprising conclusion of the theory is the existence of an intermediate range of frequencies (“anomalous region”) where the maximal current increases if the rotation frequency diminishes, i.e. for the weaker agitation intensity. This study presents the first experimental verification of these predictions for a series of bromate solutions of various concentrations in 2 M sulfuric acid. Qualitative analysis of these experimental data has confirmed the principal theoretical expectations, first of all the existence of the anomalous region of frequencies. At the same time it has been found that the previously published theoretical model based on the literature data for the parameters of the system (diffusion coefficients of solution components, rate constant of the comproportionation reaction, etc.) corresponding to dilute solutions is not able to provide a quantitative interpretation of experimental data. An advanced variant of the theory has been proposed that takes into account the dependence of these parameters on the solution composition, first of all on the effect of the acid concentration. Comparison of predictions of this model with experimental data has shown their quantitative agreement, i.e. the simulated plots for the dependence, jmax(f), turned out to be close to experimental data within the whole range of frequencies available experimentally. This result represents an unambiguous proof of validity both of the principles of the underlying theory of this process and of the predictions derived within its framework. [ DOI ]
Electroactive composite pd–polypyrrole and its catalytic properties in the reaction of styryl bromide cyanation / O. M. Nikitin, T. V. Magdesieva, O. V. Polyakova et al. // Russian Journal of Electrochemistry. — 2018. — Vol. 54, no. 7. — P. 608–611.
Electrocatalytic properties of manganese and cobalt polyporphine films toward oxygen reduction reaction / D. V. Konev, O. I. Istakova, B. Dembinska et al. // Journal of Electroanalytical Chemistry. — 2018. — Vol. 816. — P. 83–91. [ DOI ]
Electrochemical synthesis of polypyrrole in powder form / O. I. Istakova, D. V. Konev, A. T. Glazkov et al. // Journal of Solid State Electrochemistry. — 2018. [ DOI ]
Antipov A. E., Vorotyntsev M. A. Maximum current density in the reduction of the bromate anion on a rotating disk electrode: Asymptotic behavior at large thicknesses of the diffusion layer // Russian Journal of Electrochemistry. — 2018. — Vol. 54, no. 2. — P. 186–194. [ DOI ]
Vorotyntsev M. A., Аntipov A. E. Novel procedure towards approximate analytical description of bromate-anion reduction at rotating disk electrode under steady-state transport conditions // Electrochimica Acta. — 2018. — Vol. 289. — P. 272–282. [ DOI ]
Palladium nanoparticles–polypyrrole composite as effective catalyst for fluoroalkylation of alkenes / T. V. Gryaznova, M. N. Khrizanforov, K. V. Kholin et al. // Catalysis Letters. — 2018. — Vol. 148. — P. 3119–3125. [ DOI ]
Pd-polypyrrole nanocomposite in environmentally friendly synthesis of vinylnitriles using k4 fe(cn)6 / T. V. Magdesieva, O. M. Nikitin, O. V. Polyakova et al. // ChemistrySelect. — 2018. — Vol. 3, no. 16. — P. 4237–4243. [ DOI ]
Surprising dependence of the current density of bromate electroreduction on the microelectrode radius as manifestation of the autocatalytic redox-cycle (ec″) reaction mechanism / D. V. Konev, A. E. Antipov, M. M. Petrov et al. // Electrochemistry Communications. — 2018. — Vol. 86. — P. 76–79. Bromate reduction from strongly acidic solutions under steady-state conditions in the presence of a very small amount of bromine has been studied voltammetrically at disk microelectrodes of various radii. In conformity with theoretical predictions the intensity of the average current density depends on the electrode size in a non-monotonous manner, passing through a maximum for a certain radius. This behavior is a direct consequence of the autocatalytic character of this process where the non-electroactive bromate anion is reduced owing to the catalytic cycle based on the bromine/bromide redox-mediator couple. The experimentally observed dependence of the maximal current density, jmax, on the inverse disc radius, 1/r0, for electrodes of larger sizes approaches a straight line corresponding to the “strong current limit”, which exceeds the diffusion-limited current density for bromate ion. [ DOI ]
Плесков Ю. В., Воротынцев М. А., Давыдов А. Д. 67-е Ежегодное совещание Международного Электрохимического Общества, 21-26 августа 2016 г., Гаага, Нидерланды // Электрохимия. — 2017. — Т. 53, № 4. — С. 487–488. [ DOI ]
Vorotyntsev M. A., Antipov А. Е., Konev D. V. Bromate anion reduction: novel autocatalytic (ec") mechanism of electrochemical processes. its implication for redox flow batteries of high energy and power densities // Pure and Applied Chemistry. — 2017. — Vol. 89, no. 10. — P. 1429–1448. [ DOI ]
Vorotyntsev M. A., Antipov А. Е. Bromate electroreduction from acidic solution at rotating disk electrode. theory of steady-state convective-diffusion transport // Electrochimica Acta. — 2017. — Vol. 246. — P. 1217–1229. [ DOI ]
Vorotyntsev M. A., Antipov A. E. Bromate electroreduction from acidic solution at spherical microelectrode under steady-state conditions: theory for the redox-mediator autocatalytic (ec") mechanism // Electrochimica Acta. — 2017. — Vol. 258. — P. 544–553. [ DOI ]
Vorotyntsev M. A. Electrochemistry of electroactive materials: Weem-2015 and eem-2016 // Electrochimica Acta. — 2017. — Vol. 246. — P. 1259–1260. [ DOI ]
Vorotyntsev M. A., Rubashkin A. A. Electrostatic contribution to the ion solvation energy: cavity effects // Physics and Chemistry of Liquids. — 2017. — Vol. 55, no. 2. — P. 141–152. [ DOI ]
Antipov А. Е., Vorotyntsev M. A. Generalized nernst layer model for convective-diffusion transport. numerical solution for bromide ion electroreduction on inactive rotating disk electrode under steady state conditions // Russian Journal of Electrochemistry. — 2017. — Vol. 53, no. 10. — P. 1134–1142. [ DOI ]
Vorotyntsev M. A., Antipov А. Е. Mediator reduction of bromate anion at rotating disk electrode under steady-state conditions for high current densities // Russian Journal of Electrochemistry. — 2017. — Vol. 53, no. 9. — P. 919–931. [ DOI ]
Pd-ppy nanocomposite on the surface of carbon nanotubes: Synthesis and catalytic activity / K. V. Gor’kov, N. V. Talagaeva, J. C. Hierso et al. // SURFACE INNOVATIONS. — 2017. — Vol. 5, no. 3. — P. 121–129. Nanocomposites Pd-PPy@CNT have been synthesized via one-pot&one-step colloidal synthesis from mixed solution of inorganic salt and pyrrole monomer precursors. This method proposed in our previous papers leads to creation of nanoparticles of the inorganic component distributed inside polymer matrix. Nanocomposites Pd-PPy@CNT have been characterized as heterogeneous catalysts for reactions of direct C-C bond formation. The catalytic activity of the Pd-PPy@CNT nanocomposite was decreasing during repeated catalytic cycles with the same portion of the composite, because of Pd recrystallization inside the conducting polypyrrole matrix. The latter process occurs via specific mechanism of reaction between the solvent and the composite during C-C coupling reaction. [ DOI ]
Synthesis and electrocatalytic properties of palladium-polypyrrole nanocomposite in formaldehyde oxidation reaction / V. K. Gor'kov, E. V. Zolotukhina, E. R. Mustafina, M. A. Vorotyntsev // Russian Journal of Electrochemistry. — 2017. — Vol. 53. — P. 49–57. [ DOI ]
The importance of v. g. levich’s research in the development of modern electrochemistry / J. Ulstrup, M. A. Vorotyntsev, A. D. Davydov, B. M. Grafov // Russian Journal of Electrochemistry. — 2017. — Vol. 53, no. 9. — P. 893–896. [ DOI ]
К восьмидесятилетию О.А. Петрия / В. Н. Андреев, Е. В. Антипов, М. А. Воротынцев и др. // Электрохимия. — 2017. — Т. 53, № 10. — С. 1398–1399.
Михаил Романович Тарасевич (1936‒2017) (Некролог) / В. Н. Андреев, П. Атанасов, В. А. Богдановская и др. // Электрохимия. — 2017. — Т. 53, № 11. — С. 1475–1476.
Vorotyntsev M. A., Antipov А. Е., Tolmachev Y. V. 1d model of steady-state discharge process in hydrogen-bromate flow battery // Electrochimica Acta. — 2016. — Vol. 222. — P. 1555–1561. [ DOI ]
Antipov А. Е., Vorotyntsev M. A. Bromate anion electroreduction on inactive rde under steady-state conditions. numerical study of ion transport processes and comproportionation reaction // Russian Journal of Electrochemistry. — 2016. — Vol. 52, no. 10. — P. 925–932. [ DOI ]
Vorotyntsev M. A., Antipov А. Е. Bromate electroreduction via autocatalytic redox mediation: Ec" mechanism. theory for stationary 1d regime. current limitation by proton transport // Electrochimica Acta. — 2016. — Vol. 290. — P. 950–962. [ DOI ]
Efficient synthesis of a new electroactive polymer of co (ii) porphine by in-situ replacement of mg (ii) inside mg (ii) polyporphine film / S. D. Rolle, D. V. Konev, C. H. Devillers et al. // Electrochimica Acta. — 2016. — Vol. 204. — P. 276–286. [ DOI ]
Electrocatalytic activity of nanostructured palladium-polypyrrole composite in formaldehyde oxidation reaction / K. V. Gor'kov, E. V. Zolotukhina, E. R. Mustafina et al. // Doklady Physical Chemistry. — 2016. — Vol. 467, no. 1. — P. 37–40. [ DOI ]
Electrochemical synthesis of cobalt polyporphine films / O. I. Istakova, D. V. Konev, C. H. Devillers et al. // Doklady Physical Chemistry. — 2016. — Vol. 471, no. 1. — P. 181–184. [ DOI ]
Electrochemical route to co(ii) polyporphine / O. I. Istakova, D. V. Konev, A. S. Zyubin et al. // Journal of Solid State Electrochemistry. — 2016. — Vol. 20. — P. 3189–3197. [ DOI ]
Electrochromic properties of prussian blue-polypyrrole composite films in dependence on parameters of synthetic procedure / N. V. Talagaeva, E. V. Zolotukhina, P. A. Pisareva, M. A. Vorotyntsev // Journal of Solid State Electrochemistry. — 2016. — Vol. 20, no. 5. — P. 1235–1240. [ DOI ]
Electropolymerization of magnesium 5,15-di(n-methoxyphenyl)porphin / D. V. Konev, K. V. Lizgina, O. I. Istakova et al. // Russian Journal of Electrochemistry. — 2016. — Vol. 52, no. 12. — P. 1150–1158. [ DOI ]
Electroreduction of bromate anion in acidic solutions at the inactive rotating disc electrode under steady-state conditions: Numerical modeling of the process with bromate anions being in excess compared to protons / M. A. Vorotyntsev, A. E. Antipov, Y. V. Tolmachev et al. // Doklady Physical Chemistry. — 2016. — Vol. 468, no. 1. — P. 141–147. [ DOI ]
Rubashkin A. A., Vorotyntsev M. A. Electrostatic contribution to the ion solvation energy: Over-screening effect in the nonlocal dielectric response of the polar medium // Current Physical Chemistry. — 2016. — Vol. 6, no. 2. — P. 120–129. [ DOI ]
Generalization of the nernst layer model to take into account the difference in diffusivity between the components of the system in bromate reduction in steady-state one-dimensional mode: Current limiting by proton transport / А. Е. Antipov, M. A. Vorotyntsev, Y. V. Tolmachev et al. // Doklady Physical Chemistry. — 2016. — Vol. 471, no. 1. — P. 185–189. [ DOI ]
Vorotyntsev M. A., Antipov А. Е. Generalized nernst layer model: application to bromate anion electroreduction. theory for stationary 1d regime for proton transport limitations // ChemElectroChem. — 2016. — Vol. 3, no. 12. — P. 2227–2242. [ DOI ]
Novel electrochromic films based on prussian blue and polypyrrole / N. V. Talagaeva, E. V. Zolotukhina, P. A. Pisareva, M. A. Vorotyntsev // Mendeleev Communications. — 2016. — Vol. 26. — P. 119–120. [ DOI ]
Preparation of cobalt polyporphine and its catalytic properties in oxygen electroreduction / D. V. Konev, K. V. Lizgina, D. K. Khairullina et al. // Russian Journal of Electrochemistry. — 2016. — Vol. 52, no. 8. — P. 778–787. [ DOI ]
Vorotyntsev M. A., Antipov А. Е. Reduction of bromate anion via autocatalytic redox-mediation by br2/br- redox couple. theory for stationary 1d regime. effect of different nernst layer thicknesses for reactants // Journal of Electroanalytical Chemistry. — 2016. — Vol. 779. — P. 146–155. [ DOI ]
Spectroelectrochemical determination of the redox equivalent of magnesium porphine in the course of its electrooxidation / O. I. Istakova, D. V. Konev, M. A. Vorotyntsev et al. // Doklady Physical Chemistry. — 2016. — Vol. 466, no. 1. — P. 15–18. Рассмотрено применение спектроэлектрохимического метода к процессу электрополимеризации порфина магния с целью определения количества затрачиваемых электронов в расчете на молекулу мономера, что позволяет определить число связей между звеньями в получаемом полимере. На основании полученных результатов сделан вывод о строении макроцепей базового представителя нового семейства электроактивных материалов полипорфина магния. [ DOI ]
The method of double cathodic-anodic potential (current) pulses for synthesis of composite coatings prussian blue–polypyrrole on optically transparent electrodes / N. V. Talagaeva, P. A. Pisareva, A. K. Grebenko et al. // Russian Journal of Electrochemistry. — 2016. — Vol. 52, no. 1. — P. 46–52. [ DOI ]
Электровосстановление бромат-аниона в кислых растворах на неактивном ВДЭ в стационарных условиях. Численное моделирование процесса в условиях избытка бромат-аниона по сравнению с протонами / М. А. Воротынцев, А. Е. Антипов, Ю. В. Толмачев и др. // Доклады Академии наук. — 2016. — Т. 468, № 1. — С. 37–43. [ DOI ]
Антипов А. Е., Воротынцев М. А. Электровосстановление бромат-аниона на неактивном ВДЭ в стационарных условиях. Численное исследование процессов ионного транспорта и реакции конпропорционирования // Электрохимия. — 2016. — Т. 52, № 10. — С. 1039–1047.
65-Е ЕЖЕГОДНОЕ СОВЕЩАНИЕ МЕЖДУНАРОДНОГО ЭЛЕКТРОХИМИЧЕСКОГО ОБЩЕСТВА, 31 АВГУСТА–5 СЕНТЯБРЯ 2014 Г., ЛОЗАННА, ШВЕЙЦАРИЯ / М. А. Воротынцев, О. Л. Грибкова, А. Д. Давыдов и др. // Электрохимия. — 2015. — Т. 51, № 8. — С. 902–904. [ DOI ]
Electropolymerization of non-substituted mg(ii) porphine: effects of proton acceptor addition / D. V. Konev, C. H. Devillers, K. V. Lizgina et al. // Journal of Electroanalytical Chemistry. — 2015. — Vol. 737. — P. 235–242. in press. [ DOI ]
Vorotyntsev M. A., Konev D. V., Tolmachev Y. V. Electroreduction of halogen oxoanions via autocatalytic redox mediation by halide anions: novel ec" mechanism. theory for stationary 1d regime // Electrochimica Acta. — 2015. — Vol. 173. — P. 779–795. [ DOI ]
Energy cycle based on a high specific energy aqueous flow battery and its potential use for fully electric vehicles and for direct solar-to-chemical energy conversion / Y. V. Tolmachev, A. Pyatkivskiy, V. V. Ryzhov et al. // Journal of Solid State Electrochemistry. — 2015. — Vol. 19. — P. 2711–2722. [ DOI ]
In situ uv-visible spectroelectrochemistry in the course of oxidative monomer electrolysis as a tool to characterize the molecular structure of poly(mg(ii)porphine) / D. V. Konev, O. I. Istakova, О. А. Sereda et al. // Electrochimica Acta. — 2015. — Vol. 179. — P. 315–325. [ DOI ]
Nonlocal electrostatic theory of ion solvation: a combination of the overscreening effect in the dielectric response of the medium with a smeared ion charge distribution / A. A. Rubashkin, M. A. Vorotyntsev, E. M. Antipov, S. M. Aldoshin // Doklady Physical Chemistry. — 2015. — Vol. 464, no. 1. — P. 198–201. Abstract—Factors responsible for the considerable decrease in the solvation energy values calculated by Kornyshev and Sutmann using the “smeared Born sphere” model have been examined. The W values for the charge density distribution selected by Kornyshev and Sutmann and for the same distribution but confined within the ion cavity have been compared. This comparison enables the conclusion that charge smearing into the ion cavity leads only to an increase in solvation energy, and the predicted values can only be decreased down to the experimental ones for the dielectric response of a medium with the overscreening effect if the ion charge density is assumed to extend substantially beyond the cavity into the region occupied by the solvent. [ DOI ]
Silver/ion exchanger nanocomposites as low-temperature redox-catalysts for methanal oxidation / E. A. Sakardina, T. A. Kravchenko, E. V. Zolotukhina, M. A. Vorotyntsev // Electrochimica Acta. — 2015. — Vol. 179. — P. 364–371. [ DOI ]
Stability of prussian blue-polypyrrole (pb/ppy) composite films synthesized via one-step redox-reaction procedure / N. V. Talagaeva, E. V. Zolotukhina, I. Bezverkhyy et al. // Journal of Solid State Electrochemistry. — 2015. — Vol. 19. — P. 2701–2709.
Electrochemistry of electroactive materials / A. R. Hillman, P. Pickup, R. Seeber et al. // Electrochimica Acta. — 2014. — Vol. 122. — P. 1–2. [ DOI ]
Tolmachev Y. V., Vorotyntsev M. A. Fuel cells with chemically regenerative redox cathodes // Russian Journal of Electrochemistry. — 2014. — Vol. 50, no. 5. — P. 403–411. [ DOI ]
Zolotukhina Е. V., Bezverkhyy I. S., Vorotyntsev M. A. One-stage periodical anodic-cathodic double pulse deposition of nanocomposite materials. application to prussian blue/polypyrrole film coated electrodes // Electrochimica Acta. — 2014. — Vol. 122. — P. 247–258. [ DOI ]
Palladium nanoparticles – polypyrrole composite as an efficient catalyst for cyanation of aryl halides / T. V. Magdesieva, O. M. Nikitin, E. V. Zolotukhina, M. A. Vorotyntsev // Electrochimica Acta. — 2014. — Vol. 122. — P. 289–295. [ DOI ]
Synthesis of new electroactive polymers by ion-exchange replacement of mg(ii) by 2 h+ or zn(ii) cations inside mg(ii) polyporphine film, with their subsequent electrochemical transformation to condensed-structure materials / D. V. Konev, C. H. Devillers, K. V. Lizgina et al. // Electrochimica Acta. — 2014. — Vol. 122. — P. 3–10. [ DOI ]
Atomic force microscopy study of conducting polymer films near electrode's edge or grown on microband electrode / M. A. Vorotyntsev, D. V. Konev, U. Lange et al. // Electrochimica Acta. — 2013. — Vol. 110. — P. 452–458. [ DOI ]
Li-ion diffusion in lixnb9po25 / O. A. Drozhzhin, M. A. Vorotyntsev, S. R. Maduar et al. // Electrochimica Acta. — 2013. — Vol. 89. — P. 262–269.
One step and one pot method for synthesis of hybrid composite palladium–polypyrrole–carbon (pd/ppy/c) nanomaterials / E. V. Zolotukhina, M. A. Vorotyntsev, V. A. Zinovyeva et al. // Doklady Physical Chemistry. — 2013. — Vol. 449, no. 2. — P. 63–65. [ DOI ]
Synthesis of new polyporphines by replacing central ion in magnesium polyporphine / D. V. Konev, M. A. Vorotyntsev, C. H. Devillers et al. // Russian Journal of Electrochemistry. — 2013. — Vol. 49, no. 8. — P. 753–758.
Влияние протон-акцепторных добавок на процесс электрополимеризации незамещенного порфина магния / Д. В. Конев, М. А. Воротынцев, Ю. А. Добровольский и др. // Альтернативная энергетика и экология. — 2013. — № 15 (137). — С. 102–109.
НОВЫЙ МЕТОД ПЕРИОДИЧЕСКИХ ДВОЙНЫХ КАТОДНО-АНОДНЫХ ИМПУЛЬСОВ ДЛЯ ЕДИНОВРЕМЕННОГО ОСАЖДЕНИЯ КОМПОЗИТНЫХ ПЛЕНОК НЕОРГАНИЧЕСКИЙ КОМПОНЕНТ -ЭЛЕКТРОАКТИВНЫЙ ПОЛИМЕР ИЗ СМЕШАННОГО РАСТВОРА ИХ ПРЕКУРСОРОВ / Е. В. Золотухина, М. А. Воротынцев, Д. В. Конев и др. // Альтернативная энергетика и экология. — 2013. — № 13 (135). — С. 49–58. Предложен новый электрохимический метод одностадийного осаждения композитных пленок на поверхности электрода. Процедура включает в себя периодическую серию импульсов потенциала или тока переменных полярностей, налагаемых на электрод в контакте со смешанным раствором двух прекурсоров, один из которых способен формировать твердую фазу при электроокислении, а другой - при электровосстановлении. В качестве иллюстрации этот метод был применен для выращивания композитных пленок берлинская лазурь-полипиррол.
Composite materials based on polypyrrole and prussian blue nanoparticles designed for highly stable hydrogen peroxide sensor / E. V. Zolotukhina, M. A. Vorotyntsev, I. Bezverkhyy et al. // Doklady Physical Chemistry. — 2012. — Vol. 444, no. 2. — P. 75–78.
Composite materials based on prussian blue nanoparticles and polypyrrole for design of a highly stable sensor for hydrogen peroxide / E. V. Zolotukhina, M. A. Vorotyntsev, I. S. Bezverkhyy et al. // Doklady Physical Chemistry. — 2012. — Vol. 444. — P. 75–78. В результате редокспроцесса в смешанном рас творе соли железа(III), гексацианоферрата(III) и пиррола с фоновым хлоридным или нитратным электролитом получены композитные материалы берлинская лазурь–полипиррол. Методом просве чивающей электронной микроскопии (ПЭМ) по казано, что синтезированные композиты представ ляют собой наноразмерные частицы берлинской лазури, распределенные внутри полипиррольных глобул. Показано, что состав фонового электроли та влияет на морфологию образующихся компо зитных пленок. Исследована возможность приме нения полученного композита в качестве электро катализатора восстановления пероксида водорода в слабокислых средах (рН 6). Показано, что полу чение композита в нитратных средах приводит к формированию высококачественных пленок электрокатализатора, позволяющих создать вы сокостабильный сенсор для определения перок сида водорода, не инактивирующийся в жестких условиях непрерывной регистрации 1 мМ H2O2 в течение 150–160 мин, что в 80 раз превышает вре мя стабильного отклика электродов, модифици рованных чистой берлинской лазурью. [ DOI ]
Polypyrrole nanoparticles – catalyzed sonogashira coupling / T. V. Magdesieva, O. M. Nikitin, E. V. Zolotukhina et al. // Mendeleev Communications. — 2012. — Vol. 22. — P. 305–306.
Polypyrrole-palladium nanoparticles composite as efficient catalyst for suzuki-miyaura coupling / T. V. Magdesieva, O. M. Nikitin, O. A. Levitsky et al. // Journal of Molecular Catalysis A: Chemical. — 2012. — Vol. 353. — P. 50–57. Synthesis of a new hybrid material (Pd/PPy) composed of polypyrrole globules with uniformly incorporated Pd nanoparticles via direct redox reaction between pyrrole and Pd(NH3)(4)Cl-2 in water has been recently reported (V.A. Zinovyeva, M.A.Vorotyntsev, I. Bezverkhyy, D. Chaumont, J.-C. Hierso, Adv. Funct. Mater. 21 (2011) 1064-1075). In the actual study, this procedure has been extended to synthesize a series of Pd/PPy powders with variable palladium content and morphological parameters. Depending on the monomer-to-oxidant ratio in reaction mixture, average diameters of Pd and PPy particles may change in the ranges of 1.25-1.45 and 27-62 nm, respectively, the Pd concentration being within 33.5-42.0 wt.%. In general terms, decrease of the monomer-to-oxidant ratio led to formation of the Pd/PPy hybrid material with smaller diameters of both components and a higher Pd loading. The Pd/PPy composites have been studied in Suzuki-Miyaura coupling and showed high catalytic efficiency. Aryl iodides, bromides and chlorides are active. The reaction can be performed using arylboronic acids or tetraarylborates, both in organic solvents and in water, thus making the process ecologically friendly. The recycling of the catalyst is possible if its particles are immobilized on the graphite support. The comparison of two samples revealed that Pd/PPy nanocomposite with the diameter of PPy spheres of about 30 nm is more efficient in catalysis, as compared to the sample with bigger PPy spheres (about 60 nm), due to transport limitations for reagents inside the polypyrrole sphere in the latter case. For palladium/polypyrrole nanocomposites with the small diameter of PPy sphere, which are easily penetrable for the reagents and in which all Pd nanoparticles are active. Pd content in polypyrrole spheres does not influence the yield of biaryls: the more is the Pd content in polypyrrole spheres, the less amount of catalyst is necessary to obtain the same yield of biaryl. (C) 2011 Elsevier B.V. All rights reserved. [ DOI ]
A new strategy towards electroactive polymer-inorganic nanostructure composites. silver nanoparticles inside polypyrrole matrix with pendant titanocene dichloride complexes / M. A. Vorotyntsev, M. Skompska, A. Rajchowska et al. // Journal of Electroanalytical Chemistry. — 2011. — Vol. 662, no. 1. — P. 105–115. Proposed synthesis route is oriented towards hybrid materials, in which inorganic nanoparticles are distributed mostly inside the film of a polymer with conjugated chain far away from its external surface in contact with solution. Its principal idea is to perform the electrodeposition of these particles from a solute precursor in conditions where the electronic transport across the film is so slow that it represents a rate-determining step of the process and the reduction of precursor molecules takes place deeply inside the pores of the film. Such situation is realized in conjugated polymers functionalized by pendant redox-active centers, if the deposition process occurs in the potential range of their redox activity. Important advantage of this procedure consists in the absence of any additional surface-active or stabilizing agent which has to be used if the nanoparticles are incorporated into the growing film from their solubilized colloidal solution. Sizes of these particles may be varied in a controllable manner by the duration of the process and other parameters of the system. [ DOI ]
Electroactive polymeric material with condensed structure on the basis of magnesium(ii) polyporphine / M. A. Vorotyntsev, D. V. Konev, C. H. Devillers et al. // Electrochimica Acta. — 2011. — Vol. 56, no. 10. — P. 3436–3442. Previous publication of the authors presented evidences that electrochemical oxidation of Mg(II)porphine (fully unsubstituted porphyrin, MgP) in acetonitrile (AN) at a very low potential leads to deposition of films at electrode surface corresponding to typical electroactive polymers, with their reversible transition between the electron-conducting and insulating states depending on the electrode potential/oxidation level ("film of type I"). It is demonstrated in the actual publication that these films in contact with a monomer-free solution are subject to an irreversible transformation to quite a different material ("film of type II") under the influence of a higher positive potential (above 0.5-0.6 V vs. Ag/Ag+ in AN). Films with the same properties may also be obtained directly by electrooxidation of the monomer, MgP, at a sufficiently high potential. Films of type II possess a high redox activity and electronic conductivity within the whole potential interval of above 3 V in the width. Their grayish color is related to a constant absorption intensity within the whole range of wavelengths studied (320-1000 nm). On the basis of a combination of experimental observations (ATR IR and XPS) and literature data the molecular structure of this new material is assumed to be polymer chains of directly linked porphine units (with a partial loss of Mg cations), probably with multiple bonds (meso-meso and beta-beta types) between neighboring units. (C) 2010 Elsevier Ltd. All rights reserved. [ DOI ]
Electrochemistry of electroactive materials foreword / P. J. Kulesza, M. Skompska, V. Tsakova, M. A. Vorotyntsev // Electrochimica Acta. — 2011. — Vol. 56, no. 10. — P. 3417–3418. [ DOI ]
Scholz F., Vorotyntsev M. A. Gyorgy inzelt - a tribute on the occasion of his 65th birthday // Journal of Solid State Electrochemistry. — 2011. — Vol. 15, no. 11-12. — P. 2277–2278. [ DOI ]
Highly dispersed palladium-polypyrrole nanocomposites: In-water synthesis and application for catalytic arylation of heteroaromatics by direct c-h bond activation / V. A. Zinovyeva, M. A. Vorotyntsev, I. Bezverkhyy et al. // Advanced Functional Materials. — 2011. — Vol. 21, no. 6. — P. 1064–1075. Pd@PPy hybrid catalytic materials are synthesized in water via redox polymerization reaction of pyrrole with [Pd(NH(3))(4)Cl(2)]. The nanocomposites formed are composed of highly dispersed palladium particles which are either zerovalent or easily reducible, and are embedded in spherical polypyrrole globules. A unique combination of high palladium dispersion (NP size: 2.4 nm) and elevated palladium content (35 wt%) is obtained. The components of these novel nanocomposites are characterized by means of FTIR, XPS, XRD, SEM, and TEM microscopy techniques. The process of formation in solution is also monitored using UV-visible and DLS techniques. The application of these novel hybrid nanomaterials in the palladium-catalyzed direct arylation of heteroaromatics is reported. High efficiency in C-C bond formation is obtained using these materials. Furans and thiophenes are arylated by using bromoarenes. Pd@PPy nanocomposites can efficiently couple n-butyl furan and n-butyl thiophene with bromobenzene and bromoquinoline, as well as with activated or deactivated electron-poor and electron-rich functionalized bromoarenes. Thus, a clean reaction process is developed that combines the absence of organic ligand in catalytic reactions and easy recovery of Pd@PPy nanocomposite via simple filtration. Preliminary kinetic and post-catalysis studies suggest a molecular or colloidal soluble active species. These very active species are efficiently delivered by the nanocomposites and susceptible to a surprisingly uniform back redeposition within the polypyrrole support. [ DOI ]
Vorotyntsev M. A., Konev D. V. Primary and secondary distributions after a small-amplitude potential step at disk electrode coated with conducting film // Electrochimica Acta. — 2011. — Vol. 56, no. 25. — P. 9105–9112. The set of equations and boundary conditions for the "primary potential/current distribution" after a small-amplitude potential step has been analyzed for a film-coated disk electrode in contact with an electrolyte. The solution of these equations provides the overall short-time resistance of this system, R(tot), which is determined by the short-time resistance of the electrolyte solution in contact with the bare disk electrode, R(s), and the short-time film resistance to the current passage in the normal direction, R(f) = L(f)/kappa(f) pi r(o)(2)(r(o), disk radius; L(f), film thickness; kappa(f), its specific conductivity). The deviation of R(tot) from the sum of these resistances, R(s) + R(f), originates from a three-dimensional potential/current distribution in solution. Procedures to calculate the film resistance and its specific conductivity on the basis of the measured values of R(tot) and R(s) have been proposed. Similar analysis has also been carried out for the "secondary potential/current distribution" in the same system. The overall resistance for this regime is related to the short-time solution resistance, R(s), and to the total resistance of the electrode, equal to the sum of the resistance, R(f), and two interfacial resistances, R(m/f) and R(f/s). A method to determine the bulk-film parameters, R(f) and kappa(f), from data for the secondary distribution is discussed. Advantages and restrictions of the proposed route to transport parameters of a film at the electrode surface are analyzed, in comparison with existing methods of their determination. (C) 2011 Elsevier Ltd. All rights reserved. [ DOI ]
Vorotyntsev M. A., Zinovyeva V. A., Picquet M. Diffusional transport in ionic liquids: Stokes-einstein relation or "sliding sphere" model? ferrocene (fc) in imidazolium liquids // Electrochimica Acta. — 2010. — Vol. 55, no. 18. — P. 5063–5070. Our theoretical analysis of the transport of an "inert" (without specific interactions with the solvent) species inside a very viscous medium has led to the conclusion that the classical Stokes-Einstein description is not valid for these systems. Instead of it, the model of a perfectly sliding sphere was proposed for such systems, which results in the Sutherland formula for the diffusion coefficient, D=k(B)T/4 pi eta a. It is assumed that "the hydrodynamic radius", a, in this expression for very viscous ionic liquids (ILs) may be identified with the crystallographic radius of the species, as it is valid for the Stokes-Einstein relation, D=k(B)T/6 pi eta a, for the ferrocene (Fc) transport in "normal" (molecular) organic solvents. For experimental verification of these predictions the procedure based on combination of electrochemical and spectral measurements proposed in our previous paper [M.A. Vorotyntsev, V.A. Zinovyeva, D.V. Konev, M. Picquet, Gaillon, C. Rizzi, J. Phys. Chem. B 113 (2009) 10851 has been applied to study Fe properties for a set of its solutions in another ionic liquid (IL), [BMIM][BF(4)]. Both the Fe oxidation current in voltammetry and the maximum absorption in the visible range (at 440 nm) have found to be proportional to the concentration of the solute Fe. The extinction coefficient of the Fc + IL solution at 440 nm, 88.1 +/- 3.2 M(-1) cm(-1), is within the same narrow range of the values for Fc solutions in [BMIM][NTf(2)] and numerous molecular organic solvents. The value of the diffusion coefficient of Fe in [BMIM][BF(4)], (8.8 +/- 0.85) 10(-8) cm(2)/s, is about two times smaller than that in [BMIM][NTf(2)], (1.7 +/- 0.2) x 10(-7) cm(2)/s. The values of the product of the diffusion coefficient and the dynamic viscosity of the medium are close to one another for these two ILs and to the theoretical value of the product for the perfectly sliding sphere, k(B)T/4 pi a, thus confirming this model for Fe in ILs as well as that the Stokes-Einstein formula is not applicable for these systems. It has been proposed to calculate "the Sutherland coefficient", theta = k(B)T/pi D eta a, as the criterion of the compatibility of the experimental value of D with predictions of the general theory of "the partially sticking sphere" (including its particular cases of the sticking and sliding spheres). (C) 2010 Elsevier Ltd. All rights reserved. [ DOI ]
Electropolymerization of pyrrole in acetonitrile as affected by the nature of substitute and deposition potential / M. Graczyk-Zajac, S. Y. Vassiliev, M. A. Vorotyntsev, G. A. Tsirlina // Journal of Solid State Electrochemistry. — 2010. — Vol. 14, no. 11. — P. 2039–2048. We apply chronoamperometry and cyclic voltammetry to trace the effect of the deposition potential on morphological and redox properties of N-substituted polypyrrole films on platinum and ITO in acetonitrile solutions. The goal of these experiments is to check whether certain principle trends observed in the course of the film growth can be used to monitor the deposition process and to control the features of the fabricated polymer. We use STM for morphology characterization, and estimate the film thickness from its redox response in background solution. For titanocene-substituted pyrrole, we compare current transients data on the anodic electropolymerization and the monomer reduction, in order to estimate the mass transport contribution to the polymerization current within various time domains (0.1 ms-1,000 s). On the basis of all these observations, we conclude on the existence of four characteristic regions of deposition current transients and assign them to certain steps in the oligomers formation and the film growth. The region of the current growth is discussed as well in terms of traditional nucleation models. [ DOI ]
Magnesium(ii) polyporphine: The first electron-conducting polymer with directly linked unsubstituted porphyrin units obtained by electrooxidation at a very low potential / M. A. Vorotyntsev, D. V. Konev, C. H. Devillers et al. // Electrochimica Acta. — 2010. — Vol. 55, no. 22. — P. 6703–6714. Electrooxidation of magnesium(II) porphine, a totally unsubstituted porphyrin, in acetonitrile solution under potentiostatic or potentiodynamic regime leads to a polymer film at the electrode surface. Polymer deposition takes place at extremely low potential, several hundred mV less positive even compared to the deposition potential for pyrrole or EDOT (at identical monomer concentrations) in the same solvent. Film thickness can be controlled by the passed deposition charge. This material and its THF-soluble fraction have been characterized by various electrochemical methods as well as by UV-visible and IR spectroscopies, XPS. XRD and MALDI-TOF techniques. This analysis has allowed us to conclude that the polymer film is composed by chains of Mg porphine building blocks, with single bonds between the neighboring units. In the course of the potential sweep, this polymer film demonstrates a redox response resembling that of polythiophene-coated electrodes. Namely, the film is electroactive and electronically conducting in two potential ranges (p- and n-doping), which are separated by a broad interval where the film possesses a much higher resistance. The polymer may be switched between all these redox states repeatedly by the change of the potential. The film capacitance in the electroactive potential intervals is proportional to the deposition charge. (C) 2010 Elsevier Ltd. All rights reserved. [ DOI ]
Vorotyntsev M. A., Zinovyeva V. A., Konev D. V. Mechanisms of electropolymerization and redox activity: Fundamental aspects // Electropolymerization: concepts, materials and applications / Ed. by А. А. Карякин. — Wiley-VCH, Strauss GmBH, Morlenbach, 2010. — P. 27–50.
Mixed solutions of silver cation and chloride anion in acetonitrile: Voltammetric and eqcm study / M. Skompska, M. A. Vorotyntsev, A. Rajchowska, O. V. Levin // Physical Chemistry Chemical Physics. — 2010. — Vol. 12, no. 35. — P. 10525–10535. Electrochemical behavior of Pt and Au electrodes in acetonitrile solutions at different concentration ratios of Cl(-) and Ag(+) ions was studied by cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). The composition of the mixed silver chloride solutions, i.e. the amount of each component of the system (solid AgCl and solute species: Ag(+), Cl(-), AgCl(2)(-)), is governed by the solubility product of AgCl and the stability constant of AgCl(2)(-) complex and depends strongly on the ratio of the total concentrations of chloride and silver ions. In this work we analyze in detail the influence of the Cl(-)/Ag(+) concentration ratio on the value of equilibrium electrode potential and the shape of cyclic voltammograms. We explain the complicated shapes of the experimental curves observed at different concentration ranges, propose the mechanisms of the processes occurring at the electrode and substantiate them by EQCM data. [ DOI ]
Electrochemical and spectral properties of ferrocene (fc) in ionic liquid: 1-butyl-3-methylimidazolium triflimide, [bmim][ntf2]. concentration effects / M. A. Vorotyntsev, V. A. Zinovyeva, D. V. Konev et al. // Journal of Physical Chemistry B. — 2009. — Vol. 113, no. 4. — P. 1085–1099. Several earlier studies of the electrochemical oxidation of ferrocene (Fc) in room-temperature ionic liquids revealed an essentially nonlinear dependence of the oxidation current on the Fc concentration in its relatively dilute solutions, with its formally calculated diffusion coefficient strongly increasing with the concentration. Since no plausible mechanism leading to this very unusual finding had been proposed, our study of Fc solutions in 1-butyl-3-methylimidazolium triflimide, [BMIM][NTf2], was performed to verify whether the above observation originated from an incorrect determination of the dissolved Fc concentration. Our observations have demonstrated that reliable control of the Fc concentration in solution is complicated by factors such as the low amount of Fc used to prepare small-volume solutions or the great difficulty to dissolve completely a solid powder in a solvent with an extremely high viscosity. An unexpected additional complication is related to a sufficiently high volatility of Fc which manifests itself even at room temperature and especially at elevated temperatures or/and in the course of vacuum treatment of its solutions or its solid powder. Parallel measurements of electrochemical responses and UV-visible spectra for several series of Fc solutions of various concentrations (prepared with the use of different procedures) have shown a perfect parallelism between the peak current and the intensity of the absorption band in the range of 360-550 nm, leading us to the conclusion of a linear relationship between the oxidation current and the molecularly dissolved Fc concentration. The relations of these measured characteristics with the estimated Fc concentration in these solutions have demonstrated a much greater dispersion (attributed to the difficulty of a precise measurement of the latter) but without a significant deviation from the linearity in general. This finding has allowed us to estimate the diffusion coefficient of this species: D = (1.7 +/- 0.2) x 10(-7) cm(2)/s. The extinction coefficients for the maximum of the absorption band (at 440 nm) of Fc have been compared for a series of solvents: [BMIM][NTf2], acetonitrile, THF, heptane, CH2Cl2, ethanol, and toluene. A simple method to estimate reliably the concentration of solute Fc in ionic liquids based on spectroscopic measurements has been proposed, owing to the proximity of Fc absorption properties for a great variety of solvents. [ DOI ]
Electrochemical and spectral properties of some tantalocene derivatives with one pentamethylated cyclopentadienyl ligand: Cp*(cp-r)tacl2 , r = h, sime3 or (ch2)(3)nc4h4 / M. A. Vorotyntsev, M. Skompska, M. Graczyk et al. // Journal of Solid State Electrochemistry. — 2008. — Vol. 12, no. 4. — P. 421–435. Three tantalocene dichloride complexes, Cp*(Cp-R)Ta(IV)Cl-2, with one pentamethylated cyclopentadienyl ligand, Cp* = eta(5)-C5Me5, Me = CH3, and one monosubstituted cyclopentadienyl ligand, Cp-R, Cp = eta(5)-C5H5, R = H, SiMe3 or (CH2)(3)NC4H4, have been studied in acetonitrile solutions with cyclic voltammetry in the ranges of the Ta(IV) oxidation to Ta(V) or of its reduction to Ta(III). The former transition is reversible, while the latter one gives an irreversible wave due to the dissociation of the reduced complex with the loss of one chloride ligand. The redox transformation from the initial state of complex Cp*CpSiMe3TaCl2 to its oxidized state, Cp*CpSiMe3TaCl2+, and back was monitored by spectroelectrochemical measurements in a thin-layer acetonitrile solution. Kinetic data for the evolution of the UV-visible spectrum of the system in the course of the double potential step experiment were treated on the basis of two theoretical models as the reactant diffusion across the solution layer without or with taking into account ohmic losses. The values of the diffusion coefficients of the complex in its initial and oxidized (cationic) states have been estimated. It was demonstrated that this complex in each of two oxidation states, Ta(IV) or Ta(V), is represented by a single molecular form. An attempt to deposit a conducting polymer film by oxidation of the tantalocene complex containing a pyrrole group attached to the Cp ring, Cp*Cp(CH2)(3)PyTaCl2, led to a thin insulating layer at the electrode surface because of an inhibiting effect of chloride anions. [ DOI ]
Electrochemical properties of metallocene hydroxo and oxo complexes of ta(v): [cp*(cpr)taohc1]cl-+(-), r = h, sime3 or (ch2)(3)nc4h4, cp*(cp(ch2)(3)nc4h4)taocl - electrochemical deposition of conducting polymer film with incorporated tantalocene complexes / M. Skompska, M. A. Vorotyntsev, J. Goux et al. // Electrochimica Acta. — 2008. — Vol. 53, no. 11. — P. 3844–3853. Redox properties of three cationic tantalocene hydroxo complexes, [Cp*(CpR)(TaOHCI)-O-v](+), with one pentamethylated cyclopentadienyl ligand, Cp* =,eta(5)-C-5,Me-5, Me = CH3, and one monosubstituted cyclopentadienyl ligand, CpR, Cp = C5H4, R = H, SiMe3 or (CH2)(3)NC4 H-4, as well as of an oxo complex with the pyrrole-containing ligand, Cp*(Cp(CH2)(3)NC4H4)TaOCl, have been studied in acetonitrile solutions with cyclic voltammetry in the ranges of the Ta(V) reduction to Ta(IV) and to Th(Ill). Both transitions are irreversible due to the dissociation of reduced complexes with the loss of their chloride ligand. The mechanism of hydroxo complex reduction is discussed in terms of its reversible deprotonation/protonation equilibrium with the corresponding oxo complex, Cp*(CpR)TaOCl. The variation of the reduction potential for the Ta(V)/Ta(IV) transition in the negative direction in the series of tantalocene complexes: dichloride > hydroxo > oxo, as well as the difference in the behavior of the reduced (Ta(IV)) complexes (stable for dichloride but losing their chloride ligand for hydroxo and oxo complexes) was explained by the increase of the electronic density at the central metal in this series, correlated with the weakening of the Ta-Cl bond and its easier dissociation. The tantalocene centers were immobilized inside a polypyrrole matrix on the electrode surface by electropolymerization of the cationic complex [Cp*(Cp(CH2)(3)NC4H4)TaOHCl](+). This was possible after removal of the "free" chloride ions from the polymerization bath by their precipitation upon addition of TlPF6. The corresponding polymer, poly[Cp*(Cp(CH2)(3)NC4H4)TaOHCl], was found to be electroactive in contact with a background electrolyte, giving a redox response both in the polymer matrix and tantalocene potential ranges. The mechanism of the immobilized tantalocene complex transformation was the same as that for the same species dissolved in solution. (c) 2007 Elsevier Ltd. All fights reserved. [ DOI ]
Robert H. A., Kulesza P. J., Vorotyntsev M. A. Electrochemistry of electroactive materials - foreword // Electrochimica Acta. — 2008. — Vol. 53, no. 11. — P. 3742–3743. [ DOI ]
Vorotyntsev M. A., Vasilyeva S. V. Metallocene-containing conjugated polymers // Advances in Colloid and Interface Science. — 2008. — Vol. 139, no. 1-2. — P. 97–149. The paper gives a review of publications on polymers with conjugated matrices (PPy, PTh, PAni, hydrocarbon or mixed chains...) which incorporate metallocene complexes (Fe, Ru, Co; Ni, Ti, Zr, Ta) with two cyclopentadienyl ligands (Cp) and their derivatives, in particular with methylated cyclopentadienyl rings (Cp*), as well as hemi-metallocene complexes (Fe, Ru, Co, Mn), as pendant groups or inside the principal chain (part B). The information on related short-chain systems, monomers and oligomers, is also included. In part A, a brief overview of various conjugated polymer materials is presented, with their classification in accordance with the conductivity mechanism (ionic, electronic or mixed conductors) or with the structural type (linear-chain organic or mixed polymers, derivatization, metallopolymers, multi-dimensional structures, alternating and block copolymers with organic or mixed units, hybrid materials with a mixture of conjugated and inert polymers, polymers inside a solid matrix, conjugated polymers with incorporated nanoelements of transition metals, carbon, semiconductors etc. (C) 2008 Elsevier B.V. All rights reserved. [ DOI ]
Synthesis and characterization of palladium nanoparticle/polypyrrole composites / S. V. Vasilyeva, M. A. Vorotyntsev, I. Bezverkhyy et al. // Journal of Physical Chemistry C. — 2008. — Vol. 112, no. 50. — P. 19878–19885. In this work, a simple non-template one-step method for the synthesis of 2.0-2.5 nm palladium nanoparticles encapsulated into a polypyrrole shell via direct redox reaction between palladium(II) acetate and pyrrole in acetonitrile medium is described. Palladium nanoparticles are found to be able to self-organize into spherical Pd/PPy composites. The size of the Pd/PPy composite particles and Pd content in the composite depend strongly on the concentration of the palladium salt component. The combination of elemental CHNS and thermogravimetric (TGA) analysis was used to determine a high (similar to 40 wt %) content of palladium, which is in a good agreement with EDX data. The process of Pd/PPy composite formation was studied with the use of UV-vis spectroscopy and AFM spectroscopy. Properties of the obtained material were characterized by means of FTIR, XPS, XRD, SEM, and TEM techniques. [ DOI ]
Malev V. V., Levin O. V., Vorotyntsev M. A. Effect of interparticle interactions on the rate of injection of charge carriers into electroactive polymer films // Russian Journal of Electrochemistry. — 2007. — Vol. 43, no. 9. — P. 1016–1025. A phenomenological approach is used for deriving a difference equation for the density of reduced sites in films of electroactive polymers with conspicuous interparticle interactions. The approach involves simultaneous application of the lattice methods and Broensted's rule. This leads to generalization of equations for the surface layer that are known in theory of surface tension for nonelectrolytic solutions. Together with the Poisson equation for electric potential, the derived relationships make a complicated system of differential equations. Nevertheless, it can be solved by iterative methods. In the framework of this approach, expressions for the rates of injection of charge carriers into polymer films are obtained. Within a first approximation with regard to allowance for the forces of short-range interactions, their influence on the rates of injection of electrons and protons into a film is discussed. [ DOI ]
Polypyrrole films functionalized with pendant titanocene dichloride complexes: Ellipsometric study of the electropolymerization process / J. P. Correia, M. Graczyk, L. M. Abrantes, M. A. Vorotyntsev // Electrochimica Acta. — 2007. — Vol. 53, no. 3. — P. 1195–1205. Electrochemical and ellipsometric methods have been used to study the electropolymerization process of a functionalized monomer, Tc3Py (in which pyrrole is covalently bonded with fitanocene dichloride complex) on platinum electrode from a dilute monomer solution in acetonitrile. The deposition has been performed in the potentiodynamic regime. A new method for the acquisition and treatment of ellipsometric data has been proposed which allowed us to analyze the evolution of the film properties at each potential. The model of a single uniform layer was unable to describe the ellipsometric experimental observations with the necessary precision. A proper fitting of the data has been achieved considering a model of two layers having identical values of the refractive index but different values of the extinction coefficient (higher absorption for the outer layer). The analysis of the calculated values of the optical parameters of these layers has led to the assumption that both layers represent morphologically the same medium (i.e. that the whole polymer film is uniform) while the higher extinction coefficient of the external layer was due to a penetration into it of solute oligomers possessing an intensive absorption at the wavelength of the observation, 633 urn. The dependences of the thicknesses of each layer and of the whole film on the cycle number have been established, the increment of the growth (5.5 urn per cycle) being constant within the whole deposition procedure. The variation of the optical constants of the layers during the potential cycling was determined and interpreted. The calculated values for the extinction coefficients and the layer thicknesses have been used to estimate how the film absorbance changes during the potential cycling. Its comparison with the same characteristic measured directly in a spectroelectrochernical cell for a film deposited at the ITO electrode surface has provided an extra evidence in favor of the above hypothesis on the film being a morphologically uniform material, with incorporated solute oligomers in its outer layer. (c) 2007 Published by Elsevier Ltd. [ DOI ]
Vorotyntsev M. A., Scholz F. Special issue with contributions to the conference "international workshop on electrochemistry of electroactive materials" (weem-2006), repino, st-petersburg region, russia, 23-28 june 2006 // Journal of Solid State Electrochemistry. — 2007. — Vol. 11, no. 8. — P. 1007–1007. [ DOI ]
Electrochemically reduced titanocene dichloride as a catalyst of reductive dehalogenation of organic halides / T. V. Magdesieva, M. Graczyk, A. Vallat et al. // Electrochimica Acta. — 2006. — Vol. 52, no. 3. — P. 1265–1280. We have studied a reaction between the reduced form of titanocene dichloride (CP2TiCl2) and a group of organic halides: benzyl derivatives (4-X-C6H4,CH,Cl, X = H, NO2, CH3; 4-X-C6H4CH2Br, X = H, NO2, PhC(O); 4-X-C6H4CH2SCN, X = H, NO2) as well as three aryl halides (4-NO(2)C(6)H(4)Hal, Hal = Cl, Br; 4-CH3O-C6H4Cl). It has been shown that the electrochemical reduction Of CP2TiCl2 in the presence of these benzyl halides leads to a catalytic cycle resulting in the reductive dehalogenation of these organic substrates to yield mostly corresponding toluene derivatives as the main product. No debalogenation has been observed for aryl derivatives. Based on electrochemical data and digital simulation, possible schemes of the catalytic process have been outlined. For non-substituted benzyl halides halogen atom abstraction is a key step. For the reaction of nitrobenzyl halides the complexation of Ti(III) species with the nitro group takes place, with the electron transfer from Ti(III) to this group (owing to its highest coefficient in LUMO of the nitro benzyl halide) followed by an intramolecular dissociative electron redistribution in the course of the heterolytic C-Hal bond cleavage. The results for reduced titanocene dichloride centers immobilized inside a polymer film showed that the catalytic reductive dehalogenation of the p-nitrobenzyl chloride does occur but with a low efficiency because of the partial deactivation of the film due to the blocking of the electron charge transport between the electrode and catalytic centers. (c) 2006 Elsevier Ltd. All rights reserved. [ DOI ]
Electrosynthesis and properties of poly(3,4-ethylenedioxythiophene) films functionalized with titanocene dichloride complex / M. Skompska, M. A. Vorotyntsev, M. Refczynska et al. // Electrochimica Acta. — 2006. — Vol. 51, no. 11. — P. 2108–2119. Synthesis of a titanocene dichloride derivative functionalized with 3,4-etylenedioxythiophene group, Tc1EDOT (Cl2TiCpC5H4(CH2) (3,4-ethylenedioxythiophene)) has been described. Redox behavior of the monomer in tetrahydrofuran (THF), dichloromethane (DCM) and acetonitrile (AN) at different scan rates has been discussed in terms of different ability of these solvents to coordination with the reduced titanocene (Tc) complex and the solvation of Cl- anions. Electrooxidation of Tc1EDOT to get a conducting polymer film with immobilized titanocene dichloride centers and electrochemical properties of its polymer matrix in background acetonitrile solution have been compared with those of non-substituted PEDOT and PEDOT-methanol derivative (PEDOTMet), to elucidate the effect of substituents both on polymerization and redox potentials of the matrix. STM and AFM images of p(TclEDOT) films obtained with potentiodynamic and potentiostatic regimes are compared to illustrate that the films deposited at constant potential are better ordered and more compact than those obtained by cyclic voltammetry. A comparison of the cyclic voltammograms of p(Tc1EDOT) and poly(titinocene-propyl-pyrrole) (p(Tc3Py)) films in 0.1 TBAPF(6) in THF has shown that the electroactivity of the polymer matrix of p(TclEDOT) is extended to more negative potentials in comparison to that of p(Tc3Py). This results in the anodic shift of redox potential of Tc centers immobilized in p(Tc1EDOT) film with respect to that of the centers fixed in p(Tc3Py). (c) 2005 Elsevier Ltd. All rights reserved. [ DOI ]
Malev V. V., Levin O. V., Vorotyntsev M. A. Model treatment of double layer charging in electroactive polymer films with two kinds of charge carriers // Electrochimica Acta. — 2006. — Vol. 52, no. 1. — P. 133–151. To calculate such phenomenological parameters of the polymer film impedance theory, as charge transfer resistances and interfacial capacities, a well-known model of homogeneous electroactive films with two kinds of charge carriers is used. General representations of the electrochemical kinetics are applied to describe the injection processes of charge carriers into the films. The exchange current densities (i.e. inverse values of the charge transfer resistances) and the interfacial capacities are calculated as functions of the electrode potential and the bathing electrolyte solution concentration for films with both cationic and anionic nature of counter-ions. In both cases, the exchange current density of electrons as a function of the electrode potential may have an extremum or be monotonous, depending on particular values of the partition coefficient of electrons, while the capacity of the substrate/film inter-face is a monotonic function of the potential. On the contrary, the exchange current density of counter-ions is a monotonic function of the electrode potential, whereas the capacity of the film/solution interface might depend on the potential in a non-monotone way. The obtained results can be useful for a quantitative treatment of experimental data on the charge transfer resistance and the double layer capacity often observed in the Nyquist plots of the polymer film impedance. Some restrictions of the model used are also discussed. (c) 2006 Elsevier Ltd. All rights reserved. [ DOI ]
Application of a novel refinement method for accurate determination of chemical diffusion coefficients in electroactive materials by potential step technique / M. D. Levi, R. Demadrille, A. Pron et al. // Journal of the Electrochemical Society. — 2005. — Vol. 152, no. 2. — P. E61–E67. We describe application of a novel refinement method for an accurate determination of the chemical diffusion coefficient, D, and the generalized kinetic parameter, Lambda, from experimental potentiostatic intermittent titration technique (PITT) data suited for a variety of electrochemically doped electroactive polymers and inorganic intercalation host materials. The proposed, simple, two-step refinement procedure, based on earlier derived analytical expressions for the PITT response, is exemplified by the analysis of chronoamperometric responses to small-amplitude potential perturbation for p- and n-doped poly (fluorenonebithiophene) (PFDOBT-HH) thin film electrode. The initial p-doping and the entire region of n-doping of this polymer is characterized by a mixed kinetic control of the doping processes due to a combination of ohmic drops (in solution and in the bulk polymer), slow interfacial charge transfer, and diffusion kinetics. In these cases, the refinement procedure leads to meaningful values of the diffusion time constant, tau(d) and hence, D. It is believed that this relatively simple refinement procedure will facilitate accurate determination of the chemical diffusion coefficients of practical, composite insertion electrodes. (C) 2005 The Electrochemical Society. [ DOI ]
Mechanism of redox transformation of titanocene dichloride centers immobilized inside a polypyrrole matrix - eqcm and xps evidences / M. Skompska, M. A. Vorotyntsev, J. Goux et al. // Electrochimica Acta. — 2005. — Vol. 50, no. 7-8. — P. 1635–1641. We report electrochemical quartz crystal microbalance (EQCM) results for electrodeposition of titanocene derivatized polypyrrole p(Tc3Py) films and redox transformation of polypyrrole matrix and titanocene centers immobilized in the film. Films of p(Tc3Py), Tc3Py = Tc(CH2)(3)NC4H4 (Tc = Cl2TiCpCp', CP = C5H5, CP' = C5H4) Were obtained from acetonitrile solutions of monomer on a Pt disc or thin Au layer evaporated on 10 MHz quartz crystals. Polymerization efficiency, derived from the slope of the change of resonant frequency as a function of the deposition charge ranged from 54% to 75%. A gradual loss of redox activity of Tc centers during consecutive redox cycles of p(Tc3Py) film in TBAFP(6)/THF solutions is discussed in terms of elimination of Cl- ions from the Tc complex and accommodation of solvent molecule. The EQCM data are supported by XPS results. The preliminary studies performed in TEACl in AN solution have shown that the presence of Cl- ions in the solution markedly inhibits the loss of redox activity of Tc centers immobilized in the polymer matrix. (C) 2004 Elsevier Ltd. All rights reserved. [ DOI ]
Reductive electrocatalytic dehalogenation of nitrobenzyl halides: nitrophilic or halophilic attack? / T. V. Magdesieva, O. M. Nikitin, P. I. Dem'yanov et al. // Russian Chemical Bulletin. — 2005. — Vol. 54, no. 1. — P. 201–210. Electrochemical reduction of Cp2TiCl2 in the presence of benzylic halides results in their catalytic dehalogenation to form toluene derivatives. Possible schemes for the process were proposed on the basis of the results of electrochemical studies and digital simulation data. The catalytic scheme including the halophilic attack of the Ti-III complex to organic halide as a key step occurs for unsubstituted benzylic halides. In the case of nitro-substituted substrates, the reaction is strongly accelerated. In this case, an electron transfer from the reduced form of the catalyst to the NO2 group of organic halide is possibly accompanied by the intramolecular charge transfer to the C-Hal bond, thus facilitating its cleavage. Thus, the nitro group in the starting benzylic halide acts as a "redox antenna," transferring an electron to the C-Hal bond. The proposed scheme is supported by semiempirical calculations of the geometry of molecular complexes with the Ti-Hal or Ti-NO2 coordination. [ DOI ]
Heinze J., Vorotyntsev M. A. Special issue: Electrochemistry of electroactive materials // Electrochimica Acta. — 2005. — Vol. 50, no. 7-8. — P. 1449–1449. [ DOI ]
Skompska M., Vorotyntsev M. A. Influence of chloride anions on the electrodeposition and electroactivity of the polymer matrix in polypyrrole, poly(n-methylpyrrole) and polypyrrole derivatives functionalized by titanocene centers, in dry non-aqueous solutions // Journal of Solid State Electrochemistry. — 2004. — Vol. 8, no. 6. — P. 360–368. We report electrochemical studies on the influence of a small concentration of chloride ions on the electroactivity of the polymer matrix of polypyrrole (PPy), poly(N-methylpyrrole) [p(N-MePy)] and a poly(titanocene-propyl-pyrrole) derivative, p(Tc3Py) [Tc(CH2)(3)NC4H4; Tc=CpCp'TiCl2; Cp=C5H5; Cp'=C5H4] in acetonitrile (AN), tetrahydrofuran (THF) and N,N-dimethylformamide (DMF). The polymer films were obtained on Pt disc electrodes from AN solutions of the monomers containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF(6)) as the supporting electrolyte and then transferred to the corresponding monomer-free solution. Studies in Cl–containing solutions have shown that the p(Tc3Py) matrix is very sensitive to the presence of Cl- ions in all the above solvents, namely that it was subjected to electrochemical degradation at potentials above 0.1 V vs. a Ag/0.01 M Ag+ in AN reference electrode. Degradation of the p(Tc3Py) matrix was also observed in chloride-free DMF+TBAPF(6) solutions. Addition of chloride ions to the AN solution containing pyrrole, N-methylpyrrole or Tc3Py inhibits the deposition of the polymer films. On the other hand, we have found that PPy and p(N-MePy) matrices after their deposition in chloride-free AN solutions show much more stable redox responses in contact with chloride and/or DMF solutions. Possible mechanisms of these effects are discussed. [ DOI ]
Grafov B. M., Vannikov A. V., Vorotyntsev M. A. International conference "spectroelectrochemistry of conducting polymers" // Russian Journal of Electrochemistry. — 2004. — Vol. 40, no. 3. — P. 227–228.
Reactions of solute species at an electrode modified with titanocene functionalized polypyrrole film: ferrocene and titanocene dichloride / M. A. Vorotyntsev, M. Graczyk, A. Lisowska-Oleksiak et al. // Journal of Solid State Electrochemistry. — 2004. — Vol. 8, no. 10. — P. 818–827. We have studied for the first time the ability of a conducting polymer film, p(Tc3Py), representing a polypyrrole matrix with covalently attached titanocene dichloride (TcCl2) centers, to serve as an intermediator for the electron charge transport between the electrode and the reaction sites of solute reactants. The standard potential of the first of these electroactive species, ferrocene (Fc), is in the range where the polymer matrix is in its slightly oxidized state so that solute Fc species give a reversible response at the surface of this modified electrode. Another solute reactant, TcCl2, was studied in solutions in which it demonstrates a (quasi)reversible behavior at bare electrode surfaces, THF+TBAPF(6) and AN+TEACl. The standard redox potential of this species belongs to the range of the electroactivity of immobilized TcCl2, centers (where the matrix is in its non-conducting state) so that the electron charge has to be transported via stepwise redox reactions between neighboring centers inside the film. The combination, solute reactant+film, results in a greater CV current compared to the response of the film in background solution or of the solute species at the bare electrode surface. This current for THF solution even exceeds the sum of separate currents for the film and the reactant. This finding is attributed to a catalytic effect of solute species as redox intermediators for the transformation of immobilized electroactive centers leading to a greater degree of the film reduction. The presence of solute TcCl2 species results in a much greater stability of immobilized centers (compared to the corresponding reactant-free solution), both in the course of CV with the passage of the range of their response and in experiments with the film holding at the potential within this range. This holding leads to an almost constant current related to the reaction of solute species at the film/ solution interface. Our estimate shows that immobilized centers undergo above 10,000 reversible transformations (without an observed tendency to the degradation) to ensure the passage of this current. The conclusion has been drawn that immobilized TcCl, centers are able to serve as sufficiently stable redox intermediators for the electron charge transport across the film, a prerequisite for the catalytic applications of such films. [ DOI ]
Vorotyntsev M. A., Levi M. D., Aurbach D. Spatially limited diffusion coupled with ohmic potential drop and/or slow interfacial exchange: a new method to determine the diffusion time constant and external resistance from potential step (pitt) experiments // Journal of Electroanalytical Chemistry. — 2004. — Vol. 572, no. 2. — P. 299–307. We have analyzed chronoamperometric curves, I(t), after small-amplitude potential steps DeltaE (PITT technique) for the model of linear diffusion of a species inside an electroactive film, taking into account ohmic effects in the external media (solution and electrode) as well as a finite rate of the interfacial exchange. For its short-time interval, t much less than tau(d) (tau(d) is the diffusion time constant, corresponding to unlimited diffusion from the interface), three approximate analytical expressions have been proposed. One of these represents an interpolation formula between the value of the current at the start of the diffusion process, I(0) = DeltaE/R-ext (after the end of the EDL charging), and the Cottrell equation: I congruent to I(0)/(1 + Lambda(pit/tau(d))(1/2)), Eq. (9) where Lambda = R-d/R-ext is the ratio of diffusion and external (solution, electrode, etc.) resistances. Its comparison with the exact analytical solution derived recently by [Montella, J. Electroanal. Chem. 518 (2002) 61] shows the ability of this simple approximation to reproduce qualitatively the current-time dependence within the short-time interval for a wide range of A including the case where the external resistance is dominant. Another similar formula, Eq. (10), but with fractional exponents results in even better agreement with the exact result. Both analytical expressions enable one to evaluate the parameters, tau(d) and Lambda, of a real system by linear fitting of its experimental data in the corresponding coordinates, e.g., in coordinates, [I(t)t(1/2)](-1) vs. t(-1/2) for the above analytical expression. The treatment of experimental data in these coordinates also allows one to determine the upper limit of the "short-time range" in which the analytical approximation is applicable so that only the points for this time interval are used for the fitting procedure. We have also derived an analytical expression (11) for the same short-time interval, which reproduces the exact solution with a much higher precision. Since the use of this formula does not allow one to extract parameters of the process from experimental data by the simple linear fitting, we have proposed an original procedure of the data treatment to determine tau(d) and A without complicated calculation or optimization schemes. (C) 2003 Elsevier B.V. All rights reserved. [ DOI ]
Vorotyntsev M. A., Aoki K., Heinze J. Charging process in percolating systems // Russian Journal of Electrochemistry. — 2003. — Vol. 39, no. 2. — P. 182–191. Mass transport at a long distance in systems with percolating features is reduced to a nonlinear diffusion equation, with a zero value of the diffusion coefficient below the percolation threshold. Two simple models for the concentration dependence of the diffusion coefficient are exploit above this value. The corresponding nonstationary concentration profiles after a stepwise increase of me boundary concentration have been analyzed for two initial conditions, a completely exhausted medium or with the initial concentration at the percolation threshold. In the former case the change of the boundary concentration to any value above the percolation threshold leads to the front, i.e. a jump of the concentration from zero to the threshold value, which propagates through the medium with a constant intensity. The latter initial condition in the case of the linear model for the diffusion coefficient leads to a profile with the fore edge, i.e. a stepwise change of the slope. This front or fore edge are followed by the "diffusional tail" where the concentration changes gradually between the threshold and boundary values. Its shape depends essentially on the model of the diffusion coefficient. In all above variants the profile is developing as the square root of time. We have proposed an approach to the charging process in conducting polymers based on the macroheterogeneous model (ensemble of elements with various redox potentials). Since such a system possesses percolation properties the above results have been applied to the description of the charging process after a stepwise change of the applied voltage. They are able to reproduce properly some essential features found experimentally, except for me observed constancy of me front propagation speed at each applied potential. The latter fact may be attributed to the considerable potential drop due to ionic transport resistance in such materials. Linear variation of the front position is predicted by such a theory if counterions are dominant ionic species inside the film, at least for its considerable charging levels. [ DOI ]
Memory effects in functionalized conducting polymer films: titanocene derivatized polypyrrole in contact with thf solutions / M. A. Vorotyntsev, M. Skompska, E. Pousson et al. // Journal of Electroanalytical Chemistry. — 2003. — Vol. 552. — P. 307–317. Films with a polypyrrole matrix and pendant titanocene dichloride centers, p(Tc3Py), have been obtained by potentiostatic electropolymerization of the titanocene-pyrrolyl derivative, Tc3Py = Tc(CH2)(3)NC4H4 (Tc = Cl2TiCpCp', Cp = C5H5, Cp'= C5H4), in acetonitrile (AN) solutions on a Pt surface. The redox activity has been studied after the transfer of the film-coated electrode into the monomer-free solution of the same electrolyte, TBAPF(6), in THF. Contrary to the case of AN or dichloromethane solutions, one can achieve a stable redox activity of the immobilized Tc centers in THF solutions during a series of cycles. A parallel between the redox properties of the Tc complex in solution and inside the film for different solvents has been established. Various 'memory' effects have been observed, i.e. the dependence of the film response on the previous treatment of the film: (a) a prepeak at the onset of the polymer matrix oxidation (observed earlier for other functionalized conducting polymer films); (b) an 'enhanced plateau' within the range of the polymer matrix electroactivity; (c) a strong increase of the current within the reduction peak of titanocene centers after the previous passage through the range of the matrix electroactivity (compared to the response when the potential variation is limited to the titanocene potential range); (d) a shift of all oxidation waves in the positive direction as a result of the film exposure to sufficiently high negative potentials as well as their backward shift if the film is held at a potential in the 'window' between the two ranges of electroactivity. Possible interpretations of this phenomenon have been discussed. A non-equilibrium origin of this phenomenon has been proven. An attribution of the observed effects to redox processes in the polymer matrix and immobilized titanocene centers has been proposed. (C) 2003 Elsevier Science B.V. All rights reserved. [ DOI ]
Studies on the reduction of [(c5me5)(2)mo2o5] in methanol/water/acetate solutions by on-line electrochemical flowcell and electrospray mass spectrometry / J. Gun, A. Modestov, O. Lev et al. // European Journal of Inorganic Chemistry. — 2003. — no. 3. — P. 482–492. The Complex [CP*2Mo2O5] (CP* = eta(5)-C5Me5) and its electrochemical reduction products in acetic acid/acetate-buffered (pH = 4.0) water/methanol solutions were investigated by combined electrochemical (EC) flowcell and on-line electrospray ionization mass spectrometry (ESI-MS). Mono-, di-, tri-, and tetranuclear organometallic molybdenum oxides were identified in the starting solution. The effect of the relevant FSI-MS parameters (ionic mode, heated capillary voltage, and heated capillary temperature) and of the concentration on the observed distribution of ions in the mass spectrometer was studied in order to minimize side reactions in the ESI chamber. It was verified that reduction in the ESI-MS is undetectable under open-circuit conditions. The on-line electrochemical study revealed the potential-dependent formation of previously unknown mono-, di-, tri-, and tetranuclear Mo-V, Mo-IV and mixed-valence complexes. The compounds were identified by their characteristic isotope patterns and their ion trap MSn fragmentations. The observed formation potentials reflect the higher stability of the multinuclear species relative to the mononuclear ones with the same oxidation state.
Vorotyntsev M. A. Impedance of thin films with two mobile charge carriers. interfacial exchange of both species with adjacent media. effect of the double layer charges // Electrochimica Acta. — 2002. — Vol. 47, no. 13-14. — P. 2071–2079. An analytical expression for the complex impedance of a uniform thin film containing two mobile charge carriers, as a function of the frequency. has been derived for the most general case. The film is surrounded by two media allowing interfacial exchange with both those species. Besides. the charging of the electrical double layers at the interfacial boundaries has been incorporated on the basis of the Gibbs thermodynamic equation. The impedance of a Film where such exchange with both species occurs only at one of the interfacial boundaries is obtained as a particular case of the general formula. These systems represent a model of mixed electron-ion conducting films (certain conducting or redox polymers. solid electrolytes, mixed valence oxides, lithium-ion intercalation or passivation films etc) in contact with one or two 'redox active solutions' (i.e. containing an electroactive Couple) so that both the Faradaic process and ion exchange take place at their interface(s). As another example one can point out solid ionic conductors containing two mobile cations (or anions) and a 'fixed' charge, both ions being exchangeable at the interface(s). The third example is provided by a thin membrane layer containing two mobile ion species which may be exchanged with the solution(s) in contact. The expression for impedance in the cases where only one of the mobile charge carriers can cross the interface, or no species at all can be exchanged ('blocking interface'), is immediately obtained from the general formula at the infinitely large value of the corresponding charge-transfer resistance. (C) 2002 Elsevier Science Ltd. All rights reserved. [ DOI ]
Vorotyntsev M. A., Heinze J. Charging process in electron conducting polymers: dimerization model // Electrochimica Acta. — 2001. — Vol. 46, no. 20-21. — P. 3309–3324. Theory of the charging and discharging process in electron-conducting polymer films at an electrode surface has been presented. It is based on the concept of two coexisting subsystems at the polymer matrix, 'usual' sites P which can exchange with the electrode by the electronic charge in a quasi-reversible manner, and sites D where intermolecular bonds between neighboring polymer molecules can be formed. The charging and discharging of the latter subsystem may be realized along different reaction pathways, e.g. via the bond formation after the generation of two cation radicals within such site D in the course of the anodic scan while the bond dissociation may take place via a partially discharged state of the intermolecular bond. This difference leads to a hysteresis in cyclic voltammograms, first of all to a significant mutual shift of the anodic and cathodic peaks of the current originated from the redox transformations of D sites. An important feature of the P sites extracted from experimental CV data is their broad energetic inhomogeneity (dispersion of their redox potentials) responsible for plateaus of the current observed at high charging levels in both directions of the potential scan. Several approaches to the numerical integration of the kinetic equations for the sites' states have been analyzed, and qualitative predictions of the theoretical model have been illustrated. (C) 2001 Elsevier Science Ltd. All rights reserved. [ DOI ]
Redox properties of titanocene-pyrrole derivative and its electropolymerization / M. A. Vorotyntsev, M. Casalta, E. Pousson et al. // Electrochimica Acta. — 2001. — Vol. 46, no. 26-27. — P. 4017–4033. A new titanocene dichloride derivative in which one cyclopentadienyl ligand (Cp) is functionalized with a pyrrolyl ring, Tc3Py (Cl2TiCpC5H4(CH2)(3)NC4H4), has been synthesized and characterized with NMR. Its redox properties have been studied by CV in acetonitrile (AN), tetrahydrofurane (THF) and dichloromethane (DCM), in comparison with unsubstituted titanocene dichloride (Tc) and pyrrole. Ti(IV/III) transition observed within the negative potential range is a quasi-reversible reaction in THF and DCM (but without a complete recuperation of the initial reagent in the back scan) while the reoxidation peak in AN is strongly shifted in the positive direction. These results are interpreted within the framework of a 'square scheme' where the electrochemical reduction step is accompanied by the rapid substitution of one chloride ligand by the solvent molecule. The back electron transfer follows the same reaction path for weakly coordinating media (THF, DCM) whereas this process is shifted to a more positive potential in the case of strongly coordinating solvents (AN). In the positive potential range, the derivative, Tc3Py, is irreversibly oxidized (similar to pyrrole) in AN or DCM so that one can deposit a conducting polymer film with the use of different electrochemical regimes, Redox properties of its polymer matrix resemble alkyl-modified polypyrroles. The redox activity of pendant Tc groups is restricted in AN since only a thin layer of the film near the electrode surface can be reduced. A more pronounced response of immobilized Tc is observed in DCM for films polymerized in AN. Reduction peak current and reduction charge of the film depend on the potential scan rate. For sufficiently thin films and slow potential sweeps, one can reach an almost complete redox transformation of titanocene groups inside the film as evidenced by the theoretically expected ratio of polymer matrix and titanocene redox charges. Possible reasons of 'prepeak' appearance are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved. [ DOI ]
Kulesza P. J., Vorotyntsev M. A. Report on ise sponsored meeting - nato,arw weepf-2000, international workshop on electrochemistry of electroactive polymer films, 9-14 september 2000, poraj, poland // Electrochimica Acta. — 2001. — Vol. 46, no. 26-27. — P. 3940–3941.
Kulesza P. J., Vorotyntsev M. A. Special issue - electrochemistry of electroactive materials - a selection of papers presented at the nato arw weepf-2000 - (poraj, poland, september 9-14, 2000) and at the 51st annual ise meeting - (warsaw, poland, september 3-8, 2000) // Electrochimica Acta. — 2001. — Vol. 46, no. 26-27. — P. 3939–3939. [ DOI ]
Time-difference impedance spectroscopy of growing films containing a single mobile charge carrier, with application to surface films on li electrodes / M. A. Vorotyntsev, M. D. Levi, A. Schechter, D. Aurbach // Journal of Physical Chemistry B. — 2001. — Vol. 105, no. 1. — P. 188–194. In this paper we present a new approach to the analysis of electrochemical impedance spectroscopy (EIS) data for electrodes covered by passivating surface films that grow in time. The impedance of such electrodes increases in time due to the gradual growth of their thickness as well as to the change of their local characteristics. The growing part of the surface films may either be homogeneous in its structure and properties or inhomogeneous, with gradually changing properties as a function of the distance of the newly formed surface species from the metal-film interface. We show herein that the time-difference impedance spectra (DIS), i.e., the difference between two complex impedance curves, Z(omega, t(1)) - Z(omega, t(2)), measured after different periods of storage, tl and t(2), as a function of frequency may provide a very useful tool for characterizing the nature of the growing passivating films. These time-difference impedance curves (e.g., plotted in coordinates Z(imag) vs Z(real)) can be simulated both for homogeneous growing surface films on electrodes and for situations in which local properties such as the surface film's resistivity are nonuniform across the growing film. The prospects of this approach have been demonstrated in the analysis of the surface films at lithium electrodes freshly prepared and stored in alkyl carbonate mixture (ethylene-dimethyl carbonates) with a Li salt, and measured periodically by EIS. The analysis of DIS of this system has shown that during a period of several hours after the electrode's preparation in solution, the process of the surface film deposition is very complicated. Properties of the new portions of the film are varying in time so that the deposited film possesses a highly nonuniform structure. Moreover, the local characteristics of earlier formed portions are modified gradually inside the film. However, as the storage time is longer, the growth of the surface Films on the lithium electrodes becomes more homogeneous, probably due to the increased selectivity of the Li-solution reactions when the surface films are thicker. [ DOI ]
Electron and proton conducting polymers: recent developments and prospects / G. Inzelt, M. Pineri, J. W. Schultze, M. A. Vorotyntsev // Electrochimica Acta. — 2000. — Vol. 45, no. 15-16. — P. 2403–2421. The most important topics of the rapidly developing field of conducting polymers are surveyed. Particular emphasis is laid on the problems of synthesis, structure, thermodynamics and kinetic behaviour of these systems. The relevant experiences, existing models and theories are outlined. Abundant examples of the growing applications are also discussed. (C) 2000 Elsevier Science Ltd. All rights reserved. [ DOI ]
Vorotyntsev M. A., Badiali J. P., Inzelt G. Electrochemical impedance spectroscopy of thin films with two mobile charge carriers: effects of the interfacial charging // Journal of Electroanalytical Chemistry. — 1999. — Vol. 472, no. 1. — P. 7–19. In the electrochemical systems containing an excess of the background electrolyte, the faradaic process and the interfacial ('double-layer') charging are coupled to the fluxes of different charge carriers, the former being related to the diffusional transport of electroactive entities while the latter being realized mostly by ions of the supporting electrolyte. As a result, the interfacial capacitance C(dl) may simply be added in parallel to the faradaic impedance specific for each particular system (Randles & Ershler). This simple treatment is not justified in the absence of an indifferent electrolyte, if the same charged species take part in both the electrode reaction and the double layer charging. This is the case where at least one of the ions of a binary electrolyte participates in the electron transfer process or cross the interface. A similar situation arises in the case of an electrochemically active polymer film in that mixed electronic-ionic conductivity prevails, i.e. the charging of the polymer (electron transport) is accompanied by the motion of the charge-compensating counterions (:or co-ions). In such systems both interfacial processes are coupled with the same flux of the 'electroactive' component. Moreover, the distributions of both charged species inside the film are interrelated due to the electroneutrality condition and the self-consistent electric field so that their transport cannot be: considered as pure diffusion. This paper presents an analysis of the alternating current passage across a thin film containing mobile charge carriers of two types, which for the sake of specificity are referred to as 'electrons' and 'counterions' (although the results are also valid for other systems with two charge carriers). The contributions at the interfaces related to the faradaic processes (or the ion exchange) and to the double-layer charging have been taken into consideration 'ab initio'. Analytical expressions for the complex impedance have been obtained for three principal arrangements of the system, m f m' (film between two electronic conductors), s' f s ('membrane', film between two solutions) and m f s (modified electrode). Besides the parameters characterizing the transport processes of the charged species in the bulk film, these formulae contain four characteristics of each interface alpha (alpha = m f or f s), R(alpha) (charge transfer resistance), C(alpha) (interfacial capacitance), t(e)(alpha) = 1 - t(i)(alpha) ('double-layer numbers') and C(mu)alpha ('asymmetry factor'). The predicted complex-impedance plots demonstrate a greater variety of shapes compared to those predicted by traditional approaches. (C) 1999 Elsevier Science S.A. All rights reserved. [ DOI ]
Transport across an electroactive polymer film in contact with media allowing both ionic and electronic interfacial exchange / M. A. Vorotyntsev, C. Deslouis, M. M. Musiani et al. // Electrochimica Acta. — 1999. — Vol. 44, no. 12. — P. 2105–2115. In this paper, the general theory of coupled electron-ion transport inside a film having a mixed electron-ion coductivity is applied, and the a.c. impedance expressions have been calculated for the situations where the film can exchange electrons and/or ions with the surrounding media. Important example of such system is given by a conducting polymer film between two solutions containing a redox active couple ("redox active solutions") which is subjected to a faradaic process at the film surface with the participation of electronic species inside the film. As particular cases, the general formula describes also the systems where one or both interfacial boundaries can only be crossed by one type of charged species, electrons or ions. Besides the previously analysed situations, metal/film/ metal, metal/film/background solution, or a film between two background solutions, we have obtained expressions for impedance of the film between a redox active solution and a background (without redox species) one, or between a metal and a redox active solution. Theoretical predictions for the shapes of complex impedance plots in the case of a redox active solution have been demonstrated. (C) 1999 Elsevier Science Ltd. All rights reserved. [ DOI ]
Vorotyntsev M. A., Vieil E., Heinze J. Charging process in polypyrrole films: effect of ion association // Journal of Electroanalytical Chemistry. — 1998. — Vol. 450, no. 1. — P. 121–141. Cyclic voltammetric (CV) response of polypyrrole (PPy) films in contact with tetraphenylborate (TPB) acetonitrile (AN) solutions has demonstrated pronounced anomalies compared to the CV for the usual anions. The redox activity of the film is considerably reduced and both the anodic and cathodic waves consist of two peaks whose positions are strongly dependent on the ionic strength of the solution. The diminution of the charging ability has been related to a much lower maximum concentration of the doping anions (TPB) inside the film due to their large size. The observed splitting of the waves into two peaks cannot be attributed to two different electronic processes like the successive generation of 'polarons' and then 'bipolarons'. On the other hand, the hypothesis that ions inside the film may be in two different forms,'free' and 'bound', has allowed us to reproduce all the experimental features, in particular, two separated peaks at lower electrolyte concentrations, their shift in the opposite directions with +/- 60 mV slope versus logarithm of the ionic strength, independence of the peak heights or shapes of the concentration, merging of the peaks at higher ionic strengths. The same concept has been able to explain an observed separation of the broad peak for polyaniline (PANI) films in contact with mixed perchlorate-polyanion solutions into two narrower peaks upon diminishing the perchlorate content. This conclusion is in conformity with our analysis of data for the charging process of PPy in perchlorate solutions obtained earlier by in situ electrochemical quartz-crystal microbalance studies (EQCM). Experimental plots for mass versus its charge have quite different shapes for films polymerised at high or low potentials. In particular, those curves in the latter case possess opposite slopes at low and high film charges as well as a pronounced hysteresis. These observations have also been interpreted successfully within the framework of the above model of two forms of ions inside the polymer phase. The comparison has also provided evidence that 'bound' ions can be exchanged gradually with their 'free' form during the cyclic voltammetry process. This process results in a complicated shape for the mass versus charge plots including a crossing of the anodic and cathodic branches as well as a loop within the range of low charges. All these predictions of the model are in conformity with the above experimental results. The theory considers 'immobile' ions as associated with neutral sites of the polymer matrix, either due to the formation of a bond, or the ion binding by micro-cavities. An alternative approach assumes the anions to form a complex with positively charged electronic species (like 'polarons' or 'bipolarons'). However, the latter is unable even to provide a qualitative explanation of the above data, e.g. opposite signs of the slope for low and high charge ranges. (C) 1998 Elsevier Science S.A. All rights reserved. [ DOI ]
Malev V. V., Rubashkin A. A., Vorotyntsev M. A. Equilibrium properties of the system comprising an electrode modified with electroactive polymeric film and an electrolyte solution // Russian Journal of Electrochemistry. — 1997. — Vol. 33, no. 8. — P. 872–882. The distribution of potential in electroactive polymeric films localized between solution and metal is analyzed. Specific dependences of equilibrium characteristics of such systems on the composition of the adjacent solution and the electrode polarization are due to the existence in such films of three types of charge carriers, i.e., cations, anions, and electrons. To obtain conclusions about the nature of charge carriers in the modifying film and about the ratio of their concentration in the film, the data on the dependence of the total capacitance of a system, comprising a modified electrode and solution, on the electrode polarization seem to be the most informative. Taking into consideration the dependences obtained in this work in the practice of investigations of modified electrodes makes it possible to refine their real physical picture.
Influence of ionic size on the mechanism of electrochemical doping of polypyrrole films studied by cyclic voltammetry / M. D. Levi, C. Lopez, E. Vieil, M. A. Vorotyntsev // Electrochimica Acta. — 1997. — Vol. 42, no. 5. — P. 757–769. Charging/discharging process of a polypyrrole film has been studied in contact with a large-size anion (tetraphenylborate) solution in acetonitrile with a comparison to that in perchlorate solutions. The overall redox activity in the former case is significantly reduced. Nevertheless, we have been able to give a clear cyclic-voltammetry characterization of the film at various bulk-electrolyte concentrations for different sweeping rates. Those data reveal two well separated waves in each potential scan direction located in the 0.1 M NaBPh(4) solution at -0.38 V and -0.1 V (vs Ag/AgBPh(4) 0.1 M in CH3CN) in the anodic branch. The first oxidation wave obeys an ultra-thin layer mass transfer mode (temporal mode), while the second one is diffusional for sufficiently high scan rates but it approaches the same quasi-equilibrium charging regime at lower sweeping rates. Decrease of the bulk electrolyte concentration leads to a shift of both peaks in opposite directions from the merging point, keeping their shapes and intensities unchanged, with the positive or negative 60 mV slope in the semi-logarithmic coordinates. Both peaks have been attributed to a single redox transition with participation of single-charged electronic species but with different mechanisms of the charge compensation by ions. Splitting the curve into two peaks is assumed to be due to the existence of two different forms of ionic species inside the polymer phase, ”free” and ”bound” ones. Presence of some amount of bound anions in the reduced state is accompanied by the corresponding concentration of cations which are removed from the file during the first step of the charging process. The second redox wave is related to the free-anion insertion into the film. This approach is able to reproduce properly all features of experimental data. Copyright (C) 1996 Elsevier Science Ltd. [ DOI ]
Tribollet B., Vorotyntsev M. Electrochemistry of electroactive polymer films // Electrochimica Acta. — 1996. — Vol. 41, no. 11-12. — P. 1741–1741. [ DOI ]
Zholkovskij E. K., Vorotyntsev M. A., Staude E. Electrokinetic instability of solution in a plane-parallel electrochemical cell // Journal of Colloid and Interface Science. — 1996. — Vol. 181, no. 1. — P. 28–33. The current passage through a binary electrolyte solution contained in a plane-parallel cell is considered, The cell is formed by two identically ideal selective ion-exchange membranes. Nonetheless, the solution of the problem can also be employed for a cell made by two uniformly reversible electrodes, Using the corresponding boundary conditions it is taken into account that the solution can be involved in an electro- and capillary osmotic slipping at the membrane (electrode)/soIution interface provided the tangential gradients of the electrolyte concentration and/or the potential are close to the interface, The analysis of the stability of the well-known one-dimensional solution corresponding to linear concentration distribution in the cell is carried out. The analysis shows that the slipping gives rise to a hydrodynamic instability of the one-dimensional solution when colons have sufficiently low diffusion coefficients in the order of about 10(-6) cm(2) s(-1). Under this condition convective flows with periodical structure: may arise when current approaches the limiting value. (C) 1996 Academic Press, Inc. [ DOI ]
Kazarinov V. E., Vorotyntsev M. A. International workshop on electrochemistry of electroactive polymer films - (weepf'95), april 7-12, 1995, moscow, russia // Russian Journal of Electrochemistry. — 1996. — Vol. 32, no. 3. — P. 412–413.
Vorotyntsev M. A., Vieil E., Heinze J. Ionic exchange of the polypyrrole film with the pc lithium perchlorate solution during the charging process // Electrochimica Acta. — 1996. — Vol. 41, no. 11-12. — P. 1913–1920. Two theoretical approaches to the interpretation of the EQCM data for the charging-discharging process in electron-conducting polymer film coated electrodes have been proposed, with their application to systems without attached charged groups, or fixed charges. The first model treats cations and anions inside the polymer phase as ”free” mobile species which exchange with the solution may be retarded due to low values of the interfacial exchange constants. Depending on its value for the anion transfer, three limiting regimes of the charging process have been found, (1) complete ionic equilibrium with the solution, (2) ”irreversible anion transfer”, (3) ”cation compensation”, the electronic charge in the two former regimes being dominantly balanced by counter-ions whereas the latter regime being the co-ion process. Theoretical EQCM curves upon cyclic variation of the potential may possess a complicated shape, with a pronounced ”first cycle” and ”relaxation” effects as well as with a considerable hysteresis, the mass at the anodic scan being greater than that at the cathodic branch, for the anion exchange constants between regimes 2 and 3. Another model proposes existence of two different forms of ions inside the film, ”free” and ”bound”, with possible kinetic limitations for their mutual transformation but a complete equilibrium between the ”free” ions and the solution. Corresponding theoretical EQCM plots demonstrate a great variety of shapes depending on the maximum amount and thermodynamical stability of ”bound” species as well a on the kinetic exchange parameters. This model has enabled one to reproduce most of the features of experimental stabilized EQCM curves for PPy:non-monotonic variation of the film mass (”co-ion” type at low charges and ”counter-ion” one at higher charges), with a drastic change of the mass vs. charge slope at the cathodic scan and a flat extremum in the anodic branch, as well as lower mass at the cathodic scan at very low charges and a crossing point of the branches. Copyright (C) 1996 Elsevier Science. [ DOI ]
Vorotyntsev M. A., Badiali J. P., Vieil E. Multi-component diffusion approach to transport across electroactive-polymer films with two mobile charge carriers // Electrochimica Acta. — 1996. — Vol. 41, no. 7-8. — P. 1375–1381. This paper aims to apply general relations between the thermodynamical forces (gradients of electrochemical potentials) and resulting fluxes of the species to transport phenomena in a uniform film of the electroactive polymer in contact with some other conducting media, metal(s) and/or solution(s), in the case of a low-amplitude perturbation imposed. Two kinds of mobile charged species are assumed to be present inside the film, the ”electronic” and ”ionic” ones. The coefficients in the above relations (friction coefficients) are expressed through the experimentally measurable macroscopic transport parameters, the total high-frequency conductivity, migration transference numbers, binary diffusion coefficient and differential redox capacitance of the film. The non-stationary diffusion equation is found to be valid for several local characteristics of the film, in particular for electron or ion charge density, or for the low-frequency current density. This equation has been solved analytically for three usual geometries of the system, metal/film/metal, metal/film/solution and solution/film/solution, upon a sinusoidal variation of the electrode potential. The final expressions for complex impedance contain contributions of the bulk film, interfacial charge-transfer resistances and (in contact with solution(s)) bulk solution. The functional form of their frequency dependence as well as the shape of complex-impedance plots has turned out to be highly simple for all geometries, being in accordance with those derived earlier within the framework of the Nernst-Planck-Einstein equations. However, the parameters of those dependences have a form different with respect to the previous expectations, leading to a modification of the procedure to interpret experimental data. [ DOI ]
Vorotyntsev M. A., Rubashkin A. A., Badiali J. P. Potential distribution across the electroactive-polymer film between the metal and solution as a function of the film charging level // Electrochimica Acta. — 1996. — Vol. 41, no. 14. — P. 2313–2320. The distribution of the electrostatic potential across the electroactive-polymer film between the metal electrode and the solution has been analysed theoretically at various charging levels. The content of the film is determined by the electronic equilibrium with the metal and the exchange by co- and counterions with the solution. The electronic and ionic concentrations inside the film are assumed to be well below their saturation values. Two limiting shapes of the potential profile have been found, with a plateau region inside the film separating two space-charge layers near the interfaces, and with the potential drop distributed within the whole film, like that in an insulating film. In its turn, profiles with the bulk-film region have been separated into three different types, referred to as the ”membrane”, ”electron-counterion” and ”semiconductor” forms. Depending on the electronic and ionic parameters of the system, the profile may show various scenarios of evolution among these states upon sweeping the electrode polarization. Available ways to distinguish between these variants are discussed. Copyright (C) 1996 Elsevier Science Ltd. [ DOI ]
Kazarinov V. E., Vorotyntsev M. A. Report on ise sponsored meeting - international workshop on electrochemistry of electroactive polymer films (weepf'95) 7-12 april 1995, moscow, russia // Electrochimica Acta. — 1996. — Vol. 41, no. 11-12. — P. 1743–1744. [ DOI ]
Comparison of the ac-impedance of conducting polymer-films studied as electrode-supported and freestanding membranes / C. DESLOUIS, M. MUSIANI, B. TRIBOLLET, M. VOROTYNTSEV // Journal of the Electrochemical Society. — 1995. — Vol. 142, no. 6. — P. 1902–1908. The ac impedance response of a symmetrically bathed membrane consisting of a conducting polymer is modeled. The model is an extension of a recent one proposed for a conducting polymer film contacting an electronic and an ionic conductor on its two faces (modified electrode geometry) and takes into account both diffusion-migration of ionic and electronic charge carriers inside the film and charge-transfer across metal/polymer and polymer/electrolyte interfaces. The membrane impedance is calculated for various combinations of parameters in order to stress the effect of diffusion coefficients, charge-transfer resistance, and double layer capacitance at the interfaces. The impedance responses in the modified electrode and membrane geometries are compared. It is thus shown how some ambiguities in the attribution of certain features of the impedance of modified electrodes to either the polymer/electrode or polymer/electrolyte interfaces may be eliminated by this comparison. [ DOI ]
KAZARINOV V., VOROTYNTSEV M. International workshop on the electrochemistry of electroactive polymer-films (weepf-95) // Mendeleev Communications. — 1995. — no. 4. — P. 171–172.
VOROTYNTSEV M., VIEIL E., HEINZE J. Ionic exchange of a conducting-polymer film with the solution during the cyclic-voltammetry process // Russian Journal of Electrochemistry. — 1995. — Vol. 31, no. 10. — P. 1027–1035. Two theoretical approaches to the interpretation of the EQCM data for the charging-discharging process in electron-conducting polymer film coated electrodes have been proposed, with their application to systems without attached charged groups or fixed charges. The first model treats cations and anions inside the polymer phase as ”free” mobile species, whose exchange with the solution may be retarded due to low values of the interfacial exchange constants. Depending on its value for the anion transfer, three limiting regimes of the charging process have been found: (I)complete ionic equilibrium with the solution, (2) ”irreversible anion transfer”, and (3) ”cation compensation”, the electronic charge in the two former regimes being dominantly balanced by the counterion as opposed to the colon process taking place in the latter. Theoretical EQCM curves upon cyclic variation of the potential may possess a complicated shape, with a pronounced ”first cycle” and ”relaxation” effects as well as considerable hysteresis, the mass at the anodic scan being greater than that at the cathodic branch for the anion exchange constants between regimes 2 and 3. Another model proposes the existence of two different forms of ions inside the film - ”free” and ”bound” - with possible kinetic limitations for their mutual transformation but a complete equilibrium between the ”free” ions and the solution. The corresponding theoretical EQCM plots demonstrate the great variety of shapes depending on the maximum amount and thermodynamical stability of ”bound” species as well as on the kinetic exchange parameters. This model has made it possible to reproduce most of the features of experimental stabilized EQCM curves for PPy: nonmonotonic variation of the film mass (”coion” type at low charges and ”counterion” type at higher charges), with a drastic change in the mass versus charge slope at the cathodic scan and a flat extremum in the anodic branch as well as a lower mass at the cathodic scan at very low charges and a crossing point of the branches.
VOROTYNTSEV M., DAIKHIN L., LEVI M. Modeling the impedance properties of electrodes coated with electroactive polymer-films // Journal of Electroanalytical Chemistry. — 1994. — Vol. 364, no. 1-2. — P. 37–49. The response of a metal/electroactive polymer film/solution system to a low-amplitude variation of electrode polarization is analysed, taking account of both the electrodiffusion transport of electronic and ionic species in the bulk film and non-equilibrium heterogeneous charge transfer, namely electrons at the metal-film boundary and ions at the film-solution boundary. Exact analytical solutions are obtained for concentration and electric field profiles inside the film, interfacial potential drops, and complex impedance. Their dependence on frequency and the ratio of diffusion coefficients, D(e) and D(i), are analysed. For unequal values, D(e) not-equal D(i), the electric field inside the film is shown to be nonuniform and the instantaneous concentration profile is non-symmetrical with respect to the middle-plane of the film. The impedance of the system contains (in addition to the interfacial charging and solution contributions) a frequency-independent resistivity due to ohmic potential drops in the bulk film and at both interfaces as well as distributed capacitive and resistive elements. [ DOI ]
VOROTYNTSEV M., LOPEZ C., VIEIL E. On the interpretation of optical beam deflection data at excess of a background electrolyte // Journal of Electroanalytical Chemistry. — 1994. — Vol. 368, no. 1-2. — P. 155–163. A theory has been proposed for optical beam deflection at the electrodeboundary due to the interfacial transfer of an ionic component of a solution, containing excess of a single-charged background electrolyte, induced by an abrupt change in the electrode polarization. It has been demonstrated that the optical signal is generated not only by surface-transferred ionic species but also by a redistribution of background ions. As a result, it depends on the diffusion coefficients of all ionic components as well as on the derivatives of the solution refraction ind” with respect to the concentrations of both surface-transferred and background ions. The previous simplified approach disregarding the optical effect due to background electrolyte redistribution may in some cases lead even to erroneous conclusions on the direction of the interfacial flux or on the type of the ion transferred across the interface. Conditions for appropriate choice of the background electrolyte are formulated to avoid these complications. [ DOI ]
VOROTYNTSEV M., BADIALI J. Short-range electron-ion interaction effects in charging the electroactive polymer-films // Electrochimica Acta. — 1994. — Vol. 39, no. 2. — P. 289–306. This paper has analyzed the effects of the polymer/solution interfacial potential as a function of electrode polarization as well as of various short-range interactions between the charged components of the polymer phase, electronic and ionic species. Charging/discharging processes depend crucially on whether the value of interaction parameter is greater (repulsion or weak attraction between the species) or less (sufficiently strong attraction) than its critical value. In the former case it can be realized as a ”continuous” transition between the insulative and conductive states of the film at sweeping polarization, the difference between the him charging and discharging (”hysteresis”) being solely due to conventional relaxation processes (diffusion, slow interfacial transfer etc). Anodic and cathodic current peaks are generally non-symmetrical, due to the film/solution potential variation. In the latter case, two quasi-equilibrium states, low- and high-density ones, coexist within a polarization range separated by a free-energy barrier so that the charging/discharging process has features of a phase transition. It may lead to a considerable hysteresis during the cycling process, even if it is realized in a quasi-equilibrium way. Variable behaviour has been found for the partial interfacial potentials versus electrode polarization, phi(m/p)(E) and phi(p/s)(E), depending on individual charges of electronic and ionic species, on the value of the global interaction parameter as well as on the ratio of different contributions to the free energy, due to electron-electron, electron-ion and ion-ion short-range interactions. These curves may be of an S- or Z-shape, possess extrema or even a loop with the self-crossing point. Highly narrow peaks are characteristic of these systems with a strong attraction between the species. There is again an asymmetry between the anodic and cathodic peaks as well as with respect to peak potentials, due to the film/solution potential variation. The ratio of anodic and cathodic peak widths depends, on the particular type of the rate-determining process, eg slow electron or ion interfacial transfer or ”droplets” formation. [ DOI ]
Distribution of the interfacial potential drop in a situation when ionic solution components enter a surface-layer of finite thickness with fixed space-charge / M. VOROTYNTSEV, Y. ERMAKOV, V. MARKIN, A. RUBASHKIN // Russian Journal of Electrochemistry. — 1993. — Vol. 29, no. 5. — P. 730–748. An interface model was discussed where an interfacial region of finite dimensions contains a fixed space charge as well as solvent molecules and ions in equilibrium with the electrolyte. It was shown that the potential profile generally will be drastically different from that described by Gouy - Chapman - Stern theory when such an ”adsorption” layer is present in the system. The characteristics of this adsorption layer were analyzed as functions of the system parameters: the layer thickness, fixed-charge density in the layer, chemical potential difference of the ions between the layer and bulk solution, and surface charge density at the inner boundary of the adsorption layer (relative to the electrolyte solution). Plots of potential distribution in the system were reported for different values of these parameters. It was shown that the qualitative shape of the potential distribution is determined by two factors: the ratio between layer thickness and screening length within the layer, and the ratio between the layer's space charge density and the ionic charge density that would be set up within the layer if it contained no fixed charge. It was shown that Gouy - Chapman theory is admissible for a description of thin layers. When considering ”thick” layers it will be convenient to split the solution/layer/substrate system into two separate interfaces.
Mechanism of cathodic reactions at electron-conducting polymer-films - electroreduction of chloranil and tetracyanoquinodimethane at a poly-3-methylthiophene-coated glassy-carbon electrode / M. LEVI, N. ALPATOVA, E. OVSYANNIKOVA, M. VOROTYNTSEV // Journal of Electroanalytical Chemistry. — 1993. — Vol. 351, no. 1-2. — P. 271–284. The mechanism of the reversible one-electron reduction of tetracyanoquinodimethane (TCNQ), chloranil (CA) and o-dicarbollyl iron complex (o-dCFe) at a poly-3-methylthiophene-coated glassy carbon electrode in acetonitrile has been studied. Values of the formal potentials of these substances are shifted in the negative direction with respect to the polymer film by 0.54 V, 0.74 V and 1.10 V respectively, corresponding to a decrease in the mobile charge carrier concentration in the polymer film. Reduction currents for both TCNQ and CA are lower than the diffusion-limiting currents at a bare electrode. They are only slightly lower for TCNQ, but for CA they are considerably less than the diffusion currents (a ”kinetic limiting current” regime). The behaviour of the polymer film was interpreted in the framework of a p-type semiconductor model including equilibrium and non-equilibrium potential distributions across the metal + semiconductor + solution system. Reduction of o-dCFe was not observed at all because of its highly negative formal potential; hence its electrode behaviour is similar to that of an insulator. [ DOI ]
VOROTYNTSEV M. Theory of equilibrium and kinetic phenomena in electron-conducting polymers // Synthetic Metals. — 1993. — Vol. 57, no. 2-3. — P. 4556–4564. Theoretical analysis of distributions of electric potential and concentrations of electronic and ionic species across metal/polymer/solution system has shown existence of insulating (at very low charging degrees) and conductive states of the film. In the latter case the ratio of cations and anions in the film is a function of the doping degree and bulk electrolyte concentration as well as of ionic solvation properties of the film. Phenomena within the strong coion expulsion regime have been analyzed, including quasiequilibrium charging curves (at various compositions of electronic species in the film), reaction kinetics at polymer/solution interface, low-amplitude impedance. [ DOI ]
VOROTYNTSEV M., DAIKHIN L., LEVI M. Isotherms of electrochemical doping and cyclic voltammograms of electroactive polymer-films // Journal of Electroanalytical Chemistry. — 1992. — Vol. 332, no. 1-2. — P. 213–235. Various forms of the isotherm of electrochemical doping are derived in this paper both for electron-conducting and conventional redox polymer film covered electrodes. The theory is based on a lattice-gas model for all types of mobile charge species within the polymer, such as polarons or bipolarons at the macromolecules and compensating ionic countercharges, with an account of long-range interactions within the mean-field approximation. The form of the doping isotherm was found to be dependent on the prevailing type of electronic charge carriers. The potential drops at the two interfaces, metal-polymer and polymer-solution, were determined not only by the doping isotherm but also by the type of charge species within the film whose concentration is restricted in the course of doping. Drastically different mechanisms of electrochemical reactions of redox species from the solution at the surfaces of electron-conducting and conventional redox polymer films are assumed to be due to different potential distributions across these systems. The doping isotherms and corresponding voltammograms are also derived with an account of retarded electron transfer at the metal-polymer interface, and of capacitance charging of the polymer-solution boundary. The theory proposed is able to give an interpretation of various published experimental data on coulometric titration of polypyrrole and polyvinylferrocene as well as on the voltammetric behaviour of polybithiophene. [ DOI ]
DESLOUIS C., TRIBOLLET B., VOROTYNTSEV M. Diffusion-convection impedance at small electrodes // Journal of the Electrochemical Society. — 1991. — Vol. 138, no. 9. — P. 2651–2657. The ac diffusion impedance at small electrodes has been calculated as a function of frequency for convective-diffusion conditions. The dimensionless local flux was expressed as a series expansion of the dimensionless local characteristic frequency-zeta in the low-frequency range, and proportional to zeta-+1/2 in the high-frequency range. The two solutions were shown to overlap fairly well for 6 less-than-or-equal-to zeta less-than-or-equal-to 13. The overall impedance was then obtained for a small circular or a rectangular electrode. These theoretical predictions were successfully tested in pipe flow for laminar or turbulent conditions. [ DOI ]
VOROTYNTSEV M., MITYUSHEV P. Electric double-layer structure in a surface-inactive electrolyte solution - effect of the stern layer and spatial correlations of solvent polarization // Electrochimica Acta. — 1991. — Vol. 36, no. 3-4. — P. 401–409. The potential and ionic concentration distributions in the solution surface layer have been analysed at potentials near pzc. As with the Stern-Grahame approach, account is taken of the difference of the planes of closest approach for the solvent and ions to the electrode surface. Unlike the Gouy-Chapman theory, we incorporate an effect of the solvent structure resulting in the non-locality of its dielectric response to the external electric field. Our model predicts the Grahame equation for the capacitance of the system to be valid in sufficiently diluted solutions, whereas with increasing electrolyte concentration a deviation may generally take place, its sign depending on the ratio of the Stern layer thickness and the correlation length of the solvent polarization. For an aqueous 1:1 electrolyte solution it is concluded that a marked increase of "the compact layer capacity" is expected only at concentrations c approximately 1 M, in agreement with experimental data. At the same time the ionic charge distributions within the diffuse layer deviate drastically from the Gouy-Chapman one at much lower concentrations, remaining essentially smeared out in the normal direction even in rather concentrated solutions due to the non-locality of the solvent response. [ DOI ]
KORNYSHEV A., VOROTYNTSEV M. Electric-field of fractal clusters // Physica A: Statistical Mechanics and its Applications. — 1991. — Vol. 171, no. 1. — P. 98–119. We consider for the first time the electric field due to a fractal distribution of the field sources, a problem of interest for a number of aggregation phenomena. Two model examples are studied, both of which show non-trivial dependences for the field. The first one refers to a two-dimensional (2D) cluster of normally oriented dipoles where results, averaged over the rotations around the center of aggregation, are obtained. The second example is an exact solution for a 1D charged Cantor bar; various asymptotic regimes of this solution are analyzed in detail. In both cases, the decrease of the field with the distance from the fractal object within the self-similarity range is described by the corresponding fractional power laws, the exponents being determined by the Hausdorff dimension, D, of the system. When D tends to the topological dimension we investigate how the field transforms to the corresponding Euclidean mode. [ DOI ]
Electron-conducting polymers - electrochemical doping and equilibrium potential distribution across metal-polymer-solution interfaces / M. LEVI, M. VOROTYNTSEV, V. KAZARINOV, A. FRUMKIN // Synthetic Metals. — 1991. — Vol. 43, no. 1-2. — P. 2923–2925. A thermodynamic analysis of the potential distribution in an equilibrium galvanic curcuit with a conducting polymer film electrode permeable for anions has been carried out. The distribution of the total potential difference between two interfaces (metal-polymer and polymer-electrolyte solution) and, hence, the dependence of concentrations of all charged redox forms on the potential E are determined by the type of charged from that prevails in the polymer film (of polaron or bipolaron type, in particular). We consider a galvanic curcuit containing a metal current collector coated with a conducting polymer film immersed in electrolyte solution. The overall cell potential at null current, for simplicity, is measured against an electrode reversible with respect to cations in the same solution: [GRAPHICS] There exists equilibrium on the reference electrode: [GRAPHICS] The doping-dedoping processes are expressed by the equations: [GRAPHICS] Here M+ and A- are electrolyte ions, e- is electron in metal or polymer; PT-degrees is reduced form of polymer. Subscripts m, s and p indicate the phase in which the given component is contained: metal, solution and polymer respectively. Two particles correspond to the oxidized form of polymer: mobile polaron PT+ and "bound" polaron PT+ A- (the influence of other charged redox forms is considered in ). The electronic-ionic equilibrium ensures local electroneutrality everywhere inside the polymer film bulk. The problem is to express the concentration of all the components forming part of the polymer phase in terms of the concentrations of ionic solution components and the electrode potential E. [ DOI ]
Phenomenological description of dark redox reactions at electrodes coated with conducting polymer-films .2. mechanism of tetracyanoquinodimethane and iodine electroreduction at polythiophene / M. LEVI, M. VOROTYNTSEV, A. SKUNDIN, V. KAZARINOV // Journal of Electroanalytical Chemistry. — 1991. — Vol. 319, no. 1-2. — P. 243–261. Studies of the voltammetric behavior of polythiophene (PT) film electrodes in solutions containing various redox forms have established that the mechanism and kinetics of electrochemical reactions depend on the nature and concentration of mobile charge carriers within the polymer. As has been shown in Part 1 (J. Electroanal. Chem., 271 (1989) 193), at potential values close to the ferrocene/ferrocenium (Fc/Fe+) standard equilibrium potential in acetonitrile, the concentration of mobile charge carriers in PT is relatively large so that the Fc oxidation process at the polymer electrode can be described by the quasi-reversible diffusion wave equation, similar to this reaction at the uncoated platinum electrode. At the same time, the reduction process of tetracyanoquinodimethane (TCNQ) at PT is characterized, to a first approximation, by the equation for redox reactions of species adsorbed on the electrode surface (whereas at the platinum electrode this process occurs according to the diffusion mechanism). The dependence of the voltammetric peak height on the upper potential sweep limit is explained by the relatively low value of the TCNQ/TCNQ- redox couple standard potential, at which PT displays the properties of an organic semiconductor. Molecular iodine, which is a stronger oxidizer than TCNQ, is reduced at PT by the mechanism of direct injection of polarons, similar to the injection of holes in inorganic semiconductors. [ DOI ]
Computing the frequency-characteristics of turbulent-diffusion layers at microelectrodes / E. SKURYGIN, S. MARTEMYANOV, M. VOROTYNTSEV, B. GRAFOV // SOVIET ELECTROCHEMISTRY. — 1989. — Vol. 25, no. 6. — P. 685–688.
SKURYGIN E., VOROTYNTSEV M., MARTEMYANOV S. Current-density fluctuations within a turbulent-diffusion boundary-layer of constant thickness // SOVIET ELECTROCHEMISTRY. — 1989. — Vol. 25, no. 5. — P. 592–597.
VOROTYNTSEV M., IVANOV S. Energy of the image forces and the interaction of an ion with a charged group at the insulator electrolyte solution interface // SOVIET ELECTROCHEMISTRY. — 1989. — Vol. 25, no. 4. — P. 491–495.
SKURYGIN E., VOROTYNTSEV M., MARTEMYANOV S. Impurity concentration fluctuations in the diffusion layer during turbulent liquid flow // SOVIET ELECTROCHEMISTRY. — 1989. — Vol. 25, no. 5. — P. 588–592.
VOROTYNTSEV M., IVANOV S. Ionic adsorption-isotherms at homogeneous insulator electrolyte solution interfaces // SOVIET ELECTROCHEMISTRY. — 1989. — Vol. 25, no. 4. — P. 495–499.
Phenomenological description of dark redox reactions at electrodes covered with conducting polymer-films .1. mechanism and kinetics of ferrocene oxidation at polythiophene / V. KAZARINOV, M. LEVI, A. SKUNDIN, M. VOROTYNTSEV // Journal of Electroanalytical Chemistry. — 1989. — Vol. 271, no. 1-2. — P. 193–211. [ DOI ]
SKURYGIN E., VOROTYNTSEV M., MARTEMYANOV S. Space-time fluctuations of a passive impurity concentration within the diffusion boundary-layer in the turbulent-flow of a fluid // Journal of Electroanalytical Chemistry. — 1989. — Vol. 259, no. 1-2. — P. 285–293. [ DOI ]
VOROTYNTSEV M. Distribution of ionic concentrations in the diffusion layer during current flow in an incompletely dissociated electrolyte // SOVIET ELECTROCHEMISTRY. — 1988. — Vol. 24, no. 9. — P. 1150–1154.
VOROTYNTSEV M., IVANOV S. Potential drop at the insulator electrolyte solution interface // SOVIET ELECTROCHEMISTRY. — 1988. — Vol. 24, no. 6. — P. 744–746.
VOROTYNTSEV M., IVANOV S. Interaction between charges at the insulator electrolyte solution interface - ions in the compact layer // SOVIET ELECTROCHEMISTRY. — 1987. — Vol. 23, no. 6. — P. 730–735.
VOROTYNTSEV M., IVANOV S. Interaction between charges near dielectric electrolyte solution interfaces - ions in the dielectric // SOVIET ELECTROCHEMISTRY. — 1987. — Vol. 23, no. 2. — P. 191–197.
SKURYGIN E., VOROTYNTSEV M. Long-time behavior of the mixed correlation of liquid velocity and impurity-concentration fluctuations in turbulent flows // SOVIET ELECTROCHEMISTRY. — 1987. — Vol. 23, no. 7. — P. 951–951.
VOROTYNTSEV M. A new method of finding ionic adsorption parameters from experimental capacitance data // SOVIET ELECTROCHEMISTRY. — 1985. — Vol. 21, no. 3. — P. 323–325.
VOROTYNTSEV M. Adsorption of iodine ions on bismuth from mixed aqueous-solutions - interpretation of capacitance data on the basis of a new theory // SOVIET ELECTROCHEMISTRY. — 1985. — Vol. 21, no. 4. — P. 470–473.
New theoretical interpretation of data for specific adsorption of chloride ions from aqueous decinormal mixed electrolyte solutions on the mercury electrode / A. V. Shcheglov, M. A. Vorontyntsev, B. B. Damaskin, R. V. Ivanova // SOVIET ELECTROCHEMISTRY. — 1985. — Vol. 21, no. 8. — P. 1061–1063. It is the aim of this work to investigate the specific adsorption of Cl** minus ions on mercury from mixed aqueous NaF plus NaCl solutions (c equals 0. 1 M) in order to subsequently compare the experimental results with conclusions of the new theory of ionic adsorption. The mercury/aqueous solution interface was selected because it offers the possibility to attain the highest accuracy in the impedance measurements. It follows from theoretical considerations that the most sensitive region for a test of theoretical conclusions is that of low coverages, GAMMA //1, and of low ionic strength, c, of the solutions. It is shown that in the cathodic region one finds a marked decrease of W//a//d//s**o**o, evidently because of weakening of the adsorbate-adsorbent bond due to repulsion of the adsorbed ions by the field of an electrode of like charge, which is similar to the effect found in I** minus ion adsorption on bismuth or because of a change in the solvating properties of the solvent in the compact layer which may occur with changing charge of the electrode. The results obtained show that the new theory of ionic adsorption yields an adequate description of data for Cl** minus ion adsorption on mercury from mixed aqueous electrolyte solutions having a total solution concentration of c equals 0. 1 M.
VOROTYNTSEV M., IVANOV S. Statistical-mechanics of an ion ensemble adsorbed on a metal-dielectric interface // Zhurnal Eksperimentalnoi I Teoreticheskoi Fiziki. — 1985. — Vol. 88, no. 5. — P. 1729–1737.
VOROTYNTSEV M. The attraction constant in the ionic adsorption-isotherm for homogeneous metal electrolyte solution interfaces // SOVIET ELECTROCHEMISTRY. — 1985. — Vol. 21, no. 2. — P. 257–259.
KORNYSHEV A., VOROTYNTSEV M. Field-induced interfacial relaxation and electrical-properties of the compact layer // Journal of Electroanalytical Chemistry. — 1984. — Vol. 167, no. 1-2. — P. 1–14. [ DOI ]
VOROTYNTSEV M., HOLUB K. Image forces at the metal electrolyte solution interface - their dependence on electrode charge and electrolyte concentration // SOVIET ELECTROCHEMISTRY. — 1984. — Vol. 20, no. 2. — P. 243–246.
VOROTYNTSEV M., KORNYSHEV A. Models to describe the collective properties of the metal solvent interface in electric double-layer theory // SOVIET ELECTROCHEMISTRY. — 1984. — Vol. 20, no. 1. — P. 1–45.
VOROTYNTSEV M., MARTEMYANOV S., GRAFOV B. Temporal correlation of current pulsations at one or several electrodes - a technique to study hydrodynamic fluctuation characteristics of a turbulent-flow // Journal of Electroanalytical Chemistry. — 1984. — Vol. 179, no. 1-2. — P. 1–23.
Capacitance of the metal electrolyte solution interface - effects produced by the metals electron-density penetrating into the solvent / M. VOROTYNTSEV, V. IZOTOV, A. KORNYSHEV, W. SCHMICKLER // SOVIET ELECTROCHEMISTRY. — 1983. — Vol. 19, no. 3. — P. 260–267.
VOROTYNTSEV M., IZOTOV V., KORNYSHEV A. Differential capacitance of the electric double-layer in dilute-solutions of surface-inactive electrolytes and upon the specific adsorption of ions - nonlocal and non-linear effects // SOVIET ELECTROCHEMISTRY. — 1983. — Vol. 19, no. 3. — P. 364–368.
VOROTYNTSEV M., IZOTOV V. Isotherms of ionic adsorption on a homogeneous metal electrolyte-solution interface // SOVIET ELECTROCHEMISTRY. — 1983. — Vol. 19, no. 6. — P. 742–744.
KORNYSHEV A., SCHMICKLER W., VOROTYNTSEV M. Nonlocal electrostatic approach to the problem of a double-layer at a metal-electrolyte interface // Physical Review B. — 1982. — Vol. 25, no. 8. — P. 5244–5256. [ DOI ]
Nonlocal screening effects in the long-range inter-ionic interaction in a polar-solvent / A. KORNYSHEV, M. VOROTYNTSEV, H. NIELSEN, J. ULSTRUP // JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS II. — 1982. — Vol. 78. — P. 217–241. [ DOI ]
VOROTYNTSEV M. Capacitance characteristics of a polycrystalline electrode in contact with a surface-inactive electrolyte solution - influence of the size of surface crystal faces // Journal of Electroanalytical Chemistry. — 1981. — Vol. 123, no. 2. — P. 379–387. [ DOI ]
VOROTYNTSEV M. Capacitance characteristics of polycrystalline electrodes // SOVIET ELECTROCHEMISTRY. — 1981. — Vol. 17, no. 2. — P. 162–167.
KORNYSHEV A., VOROTYNTSEV M. Conductivity and space-charge phenomena in solid electrolytes with one mobile charge carrier species, a review with original material // Electrochimica Acta. — 1981. — Vol. 26, no. 3. — P. 303–323. [ DOI ]
VOROTYNTSEV M. Distribution of the potential in the electric double-layer at the contact between 2 different semi-infinite planar electrodes // SOVIET ELECTROCHEMISTRY. — 1981. — Vol. 17, no. 4. — P. 472–479.
KORNYSHEV A., VOROTYNTSEV M. Nonlocal dielectric response of the electrode-solvent interface in the double-layer problem // CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE. — 1981. — Vol. 59, no. 13. — P. 2031–2042. [ DOI ]
VOROTYNTSEV M. The capacity of an electrode consisting of uniform fragments with different electrochemical properties (approximation of linear screening in the diffuse layer) // SOVIET ELECTROCHEMISTRY. — 1981. — Vol. 17, no. 7. — P. 835–842.
KORNYSHEV A., VOROTYNTSEV M., ULSTRUP J. The effect of spatial-dispersion of the dielectric permittivity on the capacitance of thin insulating films - non-linear dependence of the inverse capacitance on film thickness // Thin Solid Films. — 1981. — Vol. 75, no. 2. — P. 105–118. [ DOI ]
VOROTYNTSEV M., MARTEMYANOV S., GRAFOV B. Closed equation for turbulent heat and mass-transfer // Zhurnal Eksperimentalnoi I Teoreticheskoi Fiziki. — 1980. — Vol. 79, no. 5. — P. 1797–1808.
VOROTYNTSEV M. Correction // Doklady Akademii nauk SSSR. — 1980. — Vol. 255, no. 6. — P. 1288–1288.
VOROTYNTSEV M., MARTEMYANOV S., GRAFOV B. Correlation of current densities in different points of an electrode - correlative links between the current fluctuations of different electrodes // SOVIET ELECTROCHEMISTRY. — 1980. — Vol. 16, no. 7. — P. 779–783.
VOROTYNTSEV M., KORNYSHEV A. Electrostatic interaction at the metal-dielectric interface // Zhurnal Eksperimentalnoi I Teoreticheskoi Fiziki. — 1980. — Vol. 78, no. 3. — P. 1008–1019.
VOROTYNTSEV M. Interaction of adsorbed ions - influence of helmholtz-layer properties // SOVIET ELECTROCHEMISTRY. — 1980. — Vol. 16, no. 9. — P. 1112–1119.
MARTEMANOV S., VOROTYNTSEV M., GRAFOV B. Mass-transfer in turbulent boundary-layer of liquids // Вестник Московского университета. Серия 2: Химия. — 1980. — no. 3. — P. 67–70.
VOROTYNTSEV M., MARTEMYANOV S., GRAFOV B. Mixed correlators of pulsations of the hydrodynamic velocity and concentration of a diffusing substance during turbulent-flow of liquid // SOVIET ELECTROCHEMISTRY. — 1980. — Vol. 16, no. 6. — P. 728–731.
KORNYSHEV A., VOROTYNTSEV M. Nonlocal electrostatic approach to the double-layer and adsorption at the electrode-electrolyte interface // Surface Science. — 1980. — Vol. 101, no. 1-3. — P. 23–48. [ DOI ]
VOROTINTSEV M., ITSKOVICH E. On mechanisms of charge division processes in the photosynthetic reaction center // Biophysics. — 1980. — Vol. 25, no. 5. — P. 787–792.
VOROTYNTSEV M., KORNYSHEV A., RUBINSHTEIN A. Possible mechanisms of controlling ionic interaction at the electrode-solution interface // SOVIET ELECTROCHEMISTRY. — 1980. — Vol. 16, no. 1. — P. 65–67.
VOROTYNTSEV M., ITSKOVICH E. Primary photosynthetic processes - the problem of rapid irreversible redistribution of electronic-energy // Journal of Theoretical Biology. — 1980. — Vol. 86, no. 2. — P. 223–236. [ DOI ]
MARTEMYANOV S., VOROTYNTSEV M., GRAFOV B. Spread of the diffusion-boundary layer along the electrode under turbulent-flow conditions // SOVIET ELECTROCHEMISTRY. — 1980. — Vol. 16, no. 5. — P. 612–615.
MARTEMYANOV S., VOROTYNTSEV M., GRAFOV B. Turbulent heat and mass-transfer near flat surfaces at moderate and small prandtl-schmidt numbers // SOVIET ELECTROCHEMISTRY. — 1980. — Vol. 16, no. 7. — P. 783–787.
VOROTYNTSEV M., ITSKOVICH E. Calculation of the discreteness-of-charge effect in the diffuse layer for a very simple helmholtz-layer model // SOVIET ELECTROCHEMISTRY. — 1979. — Vol. 15, no. 1. — P. 114–117.
MARTEMYANOV S., VOROTYNTSEV M., GRAFOV B. Convective diffusion near closely spaced, flat electrodes // SOVIET ELECTROCHEMISTRY. — 1979. — Vol. 15, no. 8. — P. 1089–1091.
MARTEMYANOV S., VOROTYNTSEV M., GRAFOV B. Derivation of the nonlocal transport-equation of matter in the turbulent-diffusion layer // SOVIET ELECTROCHEMISTRY. — 1979. — Vol. 15, no. 6. — P. 787–790.
VOROTYNTSEV M., GRAFOV B., MARTEMIANOV S. Distribution of concentrations in the laminar-flow near the surface with a sharp change of boundary-condition // Вестник Московского университета. Серия 2: Химия. — 1979. — no. 2. — P. 88–92.
VOROTYNTSEV M. Distribution of ions in the diffuse part of the double-layer, with the inclusion of discreteness-of-charge effects // SOVIET ELECTROCHEMISTRY. — 1979. — Vol. 15, no. 1. — P. 111–113.
VOROTYNTSEV M., KORNYSHEV A., RUBINSTEIN A. Electrostatic interaction of ions in solution on the electrode surface - effects of ion field penetration in the electrode // Doklady Akademii nauk SSSR. — 1979. — Vol. 248, no. 6. — P. 1321–1324.
MARTEMYANOV S., VOROTYNTSEV M., GRAFOV B. Functional form of the turbulent-diffusion coefficient in the layer next to the electrode // SOVIET ELECTROCHEMISTRY. — 1979. — Vol. 15, no. 6. — P. 790–794.
KORNYSHEV A., VOROTYNTSEV M. Model nonlocal electrostatics .3. cylindrical interface // JOURNAL OF PHYSICS C-SOLID STATE PHYSICS. — 1979. — Vol. 12, no. 22. — P. 4939–4946. [ DOI ]
VOROTYNTSEV M., KORNYSHEV A. Physical significance of an effective dielectric-constant that depends on the distance from the electrode // SOVIET ELECTROCHEMISTRY. — 1979. — Vol. 15, no. 5. — P. 560–564.
KORNYSHEV A., VOROTYNTSEV M. Analytic-expression for potential-energy of a test charge bounded by solid-state plasma // JOURNAL OF PHYSICS C-SOLID STATE PHYSICS. — 1978. — Vol. 11, no. 16. — P. L691–L694. [ DOI ]
KORNYSHEV A., VOROTYNTSEV M. Aspects of conductivity and space-charge phenomena in solid electrolytes // Electrochimica Acta. — 1978. — Vol. 23, no. 3. — P. 267–270. [ DOI ]
VOROTYNTSEV M. Discreteness-of-charge effects and the distribution of ions near interfaces // SOVIET ELECTROCHEMISTRY. — 1978. — Vol. 14, no. 6. — P. 781–783.
VOROTYNTSEV M. Discreteness-of-charge effects in inhomogeneous dielectrics // SOVIET ELECTROCHEMISTRY. — 1978. — Vol. 14, no. 6. — P. 783–786.
VOROTYNTSEV M., ITSKOVICH E. Effect of inter-molecular vibrations on shape of electronic-spectra // Optics and Spectroscopy (English translation of Optika i Spektroskopiya). — 1978. — Vol. 45, no. 2. — P. 240–246.
VOROTYNTSEV M., KORNYSHEV A., RUBINSHTEIN A. Interpolation formula for the energy of a charge near the interface between dielectrics with nonlocal properties // SOVIET ELECTROCHEMISTRY. — 1978. — Vol. 14, no. 5. — P. 704–705.
KORNYSHEV A., RUBINSHTEIN A., VOROTYNTSEV M. Model nonlocal electrostatics .1 // JOURNAL OF PHYSICS C-SOLID STATE PHYSICS. — 1978. — Vol. 11, no. 15. — P. 3307–3322. [ DOI ]
VOROTYNTSEV M. Model nonlocal electrostatics .2. spherical interface // JOURNAL OF PHYSICS C-SOLID STATE PHYSICS. — 1978. — Vol. 11, no. 15. — P. 3323–3331. [ DOI ]
VOROTYNTSEV M., GUREVICH Y., KORNYSHEV A. Unipolar conduction model in solid electrolytes // SOVIET ELECTROCHEMISTRY. — 1978. — Vol. 14, no. 1. — P. 1–6.
VOROTYNTSEV M., KORNYSHEV A. Concerning theory of voltammetric characteristics of electrochemical cells with a solid electrolyte // SOVIET ELECTROCHEMISTRY. — 1977. — Vol. 13, no. 4. — P. 470–473.
VOROTYNTSEV M., KORNYSHEV A. Direct-current in a cell with unipolar ionic-conductivity // SOVIET ELECTROCHEMISTRY. — 1977. — Vol. 13, no. 4. — P. 468–470.
ITSKOVICH E., KORNYSHEV A., VOROTYNTSEV M. Electric-current across metal-solid electrolyte interface .1. direct-current, current - voltage characteristic // Physica status solidi (A): Applied research. — 1977. — Vol. 39, no. 1. — P. 229–238. [ DOI ]
KORNYSHEV A., VOROTYNTSEV M. Electric-current across metal-solid electrolyte interface .2. low-amplitude alternating-current // Physica status solidi (A): Applied research. — 1977. — Vol. 39, no. 2. — P. 573–582. [ DOI ]
KORNYSHEV A., RUBINSHTEIN A., VOROTYNTSEV M. Image potential near a dielectric-plasma-like medium interface // Physica Status Solidi (B): Basic Research. — 1977. — Vol. 84, no. 1. — P. 125–132. [ DOI ]
Kinetics of low-temperature reactions when reactants are weakly bonded to medium / M. VOROTYNTSEV, R. DOGONADZE, M. ZAKARAYA, A. KUZNETSOV // Bulletin of the Academy of Sciences of the USSR Division of Chemical Science. — 1977. — Vol. 26, no. 6. — P. 1312–1314. [ DOI ]
VOROTYNTSEV M., CHONISHVILI G. Ortho-para ratio in electrochemical hydrogen evolution // SOVIET ELECTROCHEMISTRY. — 1977. — Vol. 13, no. 7. — P. 925–925.
VOROTYNTSEV M., KORNYSHEV A., RUBINSHTEIN A. Potential-energy of ions near electrodes - effect of penetration of ions field into electrode // SOVIET ELECTROCHEMISTRY. — 1977. — Vol. 13, no. 11. — P. 1529–1529.
Theory of atomic-molecular transformations in condensed phase at low-temperatures / R. DOGONADZE, A. KUZNETSOV, M. VOROTYNTSEV, M. ZAQARAIA // Journal of Electroanalytical Chemistry. — 1977. — Vol. 75, no. 1. — P. 315–337. [ DOI ]
VOROTYNTSEV M., SAZONOVA N. Determination of moments of aerodynamic forces acting on 3-dimensional bodies moving under conditions of law of locality // Вестник Московского университета. Серия 1: Математика. Механика. — 1976. — no. 1. — P. 104–109.
KHARKATS Y., KORNYSHEV A., VOROTYNTSEV M. Electrostatic models in theory of solutions // JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS II. — 1976. — Vol. 72. — P. 361–371. [ DOI ]
VOROTYNTSEV M., KORNYSHEV A. Model of conductivity and structure of space-charge in solid electrolyte // Doklady Akademii nauk SSSR. — 1976. — Vol. 230, no. 3. — P. 631–634.
VOROTYNTSEV M., CHONISHVILI G. Role played by tunnelling factor in proton-transfer process // Вестник Московского университета. Серия 3: Физика, астрономия. — 1976. — Vol. 17, no. 1. — P. 98–102.
Theory of atomic-molecular transformations in condensed phase at low-temperatures / M. VOROTYNTSEV, R. DOGONADZE, M. ZAKARAYA, A. KUZNETSOV // Doklady Akademii nauk SSSR. — 1976. — Vol. 226, no. 1. — P. 105–108.
DOGONADZE R., KUZNETSOV A., VOROTYNTSEV M. Theory of highly exothermic electron-transfer processes // ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS. — 1976. — Vol. 100, no. 1-2. — P. 1–16.
VOROTYNTSEV M., CHONISHVILI G. Calculation of tunnelling factor for reaction of electrochemical desorption of hydrogen // Doklady Akademii nauk SSSR. — 1975. — Vol. 225, no. 1. — P. 116–119.
BUNIMOVICH A., VOROTYNTSEV M., SAZONOVA N. Determination of aerodynamic characteristics of bodies in translation under conditions of law of locality // Вестник Московского университета. Серия 1: Математика. Механика. — 1975. — no. 6. — P. 111–116.
Theory of light-absorption by ions in solution / R. DOGONADZE, E. ITSKOVITCH, A. KUZNETSOV, M. VOROTYNTSEV // The Journal of physical chemistry. — 1975. — Vol. 79, no. 26. — P. 2827–2834. [ DOI ]
Theory of low-temperature chemical-reactions / M. VOROTYNTSEV, R. DOGONADZE, M. ZAKARAYA, A. KUZNETSOV // Doklady Akademii nauk SSSR. — 1975. — Vol. 223, no. 5. — P. 1168–1171.
KHARKATS Y., MADUMARO A., VOROTYNT M. Application of density matrix-method in quantum-mechanical calculation of bridge-assisted electron-transfer probability in polar media // JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS II. — 1974. — Vol. 70, no. 9. — P. 1578–1590. [ DOI ]
VOROTYNT M., DOGONADZ R., KUZNETSO A. Theory of proton-transfer processes in a polar medium // Doklady Akademii nauk SSSR. — 1973. — Vol. 209, no. 5. — P. 1135–1138.
DOGONADZ R., KUZNETSO A., VOROTYNT M. Kinetics of adiabatic and nonadiabatic reactions at metal and semiconductor electrodes // Croatica Chemica Acta. — 1972. — Vol. 44, no. 2. — P. 257–&.
DOGONADZ R., KUZNETSO A., VOROTYNT M. Theory of nonradiative transitions in polar media .1. processes without mixing of quantum and classical degrees of freedom // Physica Status Solidi (B): Basic Research. — 1972. — Vol. 54, no. 1. — P. 125–134. [ DOI ]
DOGONADZ R., KUZNETSO A., VOROTYNT M. Theory of nonradiative transitions in polar media .2. processes with mixing of quantum and classical degrees of freedom // Physica Status Solidi (B): Basic Research. — 1972. — Vol. 54, no. 2. — P. 425–433. [ DOI ]
DOGONADZ R., KUZNETSO A., VOROTYNT M. On theory of adiabatic and non-adiabatic electrochemical reactions // Journal of Electroanalytical Chemistry. — 1970. — Vol. 25, no. 2. — P. 17–&.
VOROTYNT M., DOGONADZ R., KUZNETSO A. Probability of charge transfer in a polar environment with a continuous vibrational spectrum // Doklady Akademii nauk SSSR. — 1970. — Vol. 195, no. 5. — P. 1135–&.