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G. V. Zhutaeva G. V. Boikova K. A. Radyushkina M. R. Tarasevich 《Russian Journal of Electrochemistry》2002,38(10):1110-1115
The electrochemical behavior and electrocatalytic activity of cobalt tetra(p-methoxyphenyl)porphyrin (CoTMPP) adsorbed at anisotropic pyrographite in the reaction of oxygen electroreduction in 0.5 M H2SO4 is studied by cyclic voltammetry. Dependences of voltammogram parameters (currents and potentials of maximums of the Co3+/2+TMPP redox reaction, numbers of adsorbed and working molecules, values of uncompensated layer resistance) on the adsorbate concentration (10–6 to 10–3 M) in chloroform are analyzed. It is concluded that adsorbed molecules change their orientation from a flat to an inclined position at c
CoMPP> 5 × 10–5 M. The optimum, as to the effectiveness of CoTMPP in the oxygen reduction, is the adsorption layer thickness close to the thickness of a monolayer of flatly-oriented molecules. 相似文献
2.
M. R. Tarasevich G. V. Zhutaeva M. V. Radina Z. R. Karichev E. A. Teishev J. H. Miners P. Goueres E. Sanchez-Corteron 《Russian Journal of Electrochemistry》2003,39(10):1094-1098
The activity of composite catalysts, Pt and Co-porphyrin- or Fe-phthalocyanine-based pyropolymers on low-disperse carbonaceous carriers (graphite, carbon black), in the oxygen and H2O2electroreduction in 1 M KOH is studied. Kinetic parameters of oxygen electroreduction are determined from experiments with rotating disk and model floating electrodes. Possible mechanism of the oxygen electroreduction reaction is discussed; it includes a slow stage of attachment of the second electron on the pyropolymer/carbonaceous carrier or joining the first electron (under the conditions of Temkin adsorption) on the platinum/graphite catalysts. 相似文献
3.
G. V. Zhutaeva M. R. Tarasevich M. V. Radina I. S. Chernyshova 《Russian Journal of Electrochemistry》2009,45(9):1080-1088
The electrochemical behavior of composite materials based on phenyl substituted cobalt porphyrins and Nafion is studied. Several
cobalt porphyrins with presumably predictable variation of their hydrophilic/hydrophobic properties due to different donor
and acceptor substituents in the para position of phenyl rings are synthesized and studied. It is shown that introduction of Nafion into a system with acceptor
substituents results in a significant acceleration of the model oxygen reduction reaction. This allows assuming that a bond
between a proton of the Nafion sulfogroup with the porphyrin active center is most probable in this very group of porphyrins,
which facilitates the protonation step required for activation of the oxygen molecule. A certain correlation is found between
the model reaction of oxygen electroreduction (halfwave potential, reaction rate constant) and Hammett constant varying as
dependent on the nature of peripheric substituents. 相似文献
4.
Tarasevich M. R. Radyushkina K. A. Zhutaeva G. V. 《Russian Journal of Electrochemistry》2004,40(11):1174-1187
Results of research into structural and electrocatalytic properties of metalloporphyrins and metallophthalocyanines pyrolyzed on carbon supports of various dispersion degree in the oxygen electroreduction reaction (OER) are analyzed. The pyrolysis products (pyropolymers) that form at T 800° in inert atmosphere contain centers Co(Fe)–N surrounded by carbon particles. The oxygen electroreduction reaction on pyropolymers in acid and alkali solutions is studied on a model gas-diffusion electrode and a rotating ring–disk electrode. The slopes of Tafel plots in an acid solution are 60 and 120 mV. On a disk electrode covered with a pyropolymer, the intermediate product of OER, hydrogen peroxide, is fixed on the ring electrode throughout the entire range of OER potentials. The activity of pyropolymers in the hydrogen peroxide electroreduction reaction in an acid solution is insignificant. In an acid environment, OER occurs via a parallel–successive mechanism with a slow stage of the attachment of the first electron. In alkali media, slopes of Tafel plots equal 40 and 120 mV at low and high polarizations, respectively. The amount of hydrogen peroxide fixed on the ring electrode corresponds to 2–5% of the disk electrode current. A pyropolymer is active in the hydrogen peroxide reduction. The slow stage in OER in an alkali environment is the attachment of the second electron at a low polarization and the attachment of the first electron, at a high polarization. In acid and alkali solutions a pyropolymer is methanol-tolerant. 相似文献
5.
G. V. Zhutaeva K. A. Radyushkina M. A. Marinich G. P. Bogatyreva M. R. Tarasevich 《Russian Journal of Electrochemistry》2001,37(10):1059-1064
The oxygen electroreduction in acid solutions on electrodes of disperse synthetic diamond powder promoted with cobalt tetra(p-methoxyphenyl)porphyrin or its pyrolysis products is studied. A floating gas-diffusion electrode and an RDE of isotropic pyrocarbon are used in experiments; in the latter case, the catalyst is immobilized in a Nafion solution. Two types of diamond, with specific area of 5.8 and 170 m2/g, are used. The results are compared with similar data found for promoted acetylene black. A significant effect of the carbon support on electrocatalytical properties of cobalt porphyrin pyrolyzed on it is found. 相似文献
6.
V. A. Bogdanovskaya E. M. Kol’tsova M. R. Tarasevich M. V. Radina G. V. Zhutaeva A. V. Kuzov N. N. Gavrilova 《Russian Journal of Electrochemistry》2016,52(8):723-734
Results on the development of new cathodic catalysts (monoplatinum and cobalt-modified platinum) applied on carbon nanotubes are shown. By means of a complex of electrochemical and structural techniques, it is shown that as regards their activity under model conditions and within membrane-electrode assembles, the catalysts synthesized by the polyol method are close to commercial monoplatinum systems with the same mass content of platinum (20 wt %) and their corrosion stability is double that of commercial catalysts. Platinum modified with cobalt is characterized by still higher stability, which allows considering these catalytic systems as the candidates to be used in fuel cells after the corresponding optimization. 相似文献
7.
V. S. Tyurin G. P. Bogatyreva G. V. Zhutaeva N. V. Korovin M. A. Marinich K. A. Radyushkina M. R. Tarasevich A. Yu. Yuskov 《Russian Journal of Electrochemistry》2001,37(10):1085-1088
The activity of composite materials (acetylene black or ultrafinely divided dynamic diamond + Co-pyropolymer + Nafion solution) in the oxygen electroreduction in a 0.5 M H2SO4solution and when using a Nafion-117 film 200 m thick as a proton-conducting electrolyte is compared. It is established that the addition of Nafion in the active mass leads to a decrease in the electrocatalytic activity of the latter. The same composite catalyst (at an insignificant thickness of the active layer) in contact with a solid polymer electrode makes it possible to obtain current densities ten times those in a sulfuric acid solution. Possible reasons for these effects are discussed. 相似文献
8.
Galina V. Zhutaeva Vera A. Bogdanovskaya Elena S. Davydova Leonid P. Kazanskii Michail R. Tarasevich 《Journal of Solid State Electrochemistry》2014,18(5):1319-1334
The kinetic parameters of oxygen reduction reaction on Vulcan XC72R carbon black, carbon black modified by pyrolysis products of cobalt 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrine named by MXC72R, and commercial Pt/C platinum catalyst have been considered. Comparison of their electrochemical properties including pH influence in a broad interval from 0.3 to 14.6 has shown platinum-similar behavior of MXC72R in the reaction under study. An increasing order of electrochemical activity for oxygen reduction reaction is obtained, namely XC72R?<?MXC72R?<?Pt/C. The mechanism of oxygen reduction reaction is discussed emphasizing the important accelerating role of protonation of adsorbed oxygen molecule and inhibiting role of oxygen-containing species (formed due to water molecule discharge) and strongly adsorbed foreign species. The importance of the research on oxygen reduction reaction in a broad pH interval to evaluate the efficiency of various precious metal-free catalytic systems in comparison to platinum is emphasized. 相似文献
9.
V. A. Bogdanovskaya M. R. Tarasevich L. N. Kuznetsova G. V. Zhutaeva O. V. Lozovaya 《Russian Journal of Electrochemistry》2010,46(8):925-933
Bimetallic catalysts PtM (M = Co, Ni, or Cr) are synthesized. They exceed purely platinum commercial catalyst E-TEK (20 wt
% Pt) in its mass activity (mA/mgPt) and specific activity (mA/cPt2) in the oxygen reduction reaction. According to XRD data, the high-temperature synthesis involving metal N4-complexes, chloroplatinic acid, and XC72 carbon black as precursors, yields alloys (or solid solutions) of the metals. The
higher activity of the bimetallic catalyst PtCo/C is likely to be caused by the practically entire formation of solid solutions
(Pt3Co and PtCo), unlike PtNi and PtCr where nickel and chromium exist also as oxides that decorate the electrode surface and
partly block active centers. It is shown that the mechanism of the oxygen reduction reaction at the synthesized catalysts
is similar to that of oxygen reduction at the purely platinum catalyst. The slow stage in the process is transfer of the 1st
electron; at potentials more positive than 0.6 V the reaction mainly yields water. The higher electrocatalytic activity of
the bimetallic systems is caused by the alloy formation, which leads to changes in the bond length between platinum atoms.
The achieving of the optimal bond length, as a result of the alloy formation, provides appropriate conditions for dissociative
adsorption of oxygen molecules; the surface coverage with oxygen-containing particles adsorbed from water (which block active
centers for O2 adsorption) decreased. The increase in the activity may also be caused by the formation of the “core-shell” structures whose
surface is enriched with platinum whose surface properties are changed under the ligand action of the core formed by the metal
alloy 相似文献
10.
Bazanov M. I. Petrov A. V. Zhutaeva G. V. Turchaninova I. V. Andrievski G. Evseev A. A. 《Russian Journal of Electrochemistry》2004,40(11):1198-1204
Electrochemical and electrocatalytic properties of differently structured macroheterocyclic complexes (MC) are studied by a cyclic voltammetry method. The potential at half-height of the rising branch of the peak current of the first stage in the oxygen reduction,
, is used for estimating the electrocatalytic action of complexes. Major structural factors that exert maximum electrocatalytic action on the oxygen reduction are determined by comparing
for different MC. The maximum electrocatalytic activity in this reaction in 0.1 M KOH is exhibited by complexes containing cobalt and iron as the central metal atom as well as polymeric compounds and those having electron-donating substituents in the organic ligand. 相似文献
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