V. N. Andreev

Electrochemical template synthesis of an polyaniline composite with polymeric perfluorinated sulfo cationite

Combining a tracer technique with electrochemical measurements offers a unique opportunity to study the mechanism of anodic synthesis of a composite based on an electron-conducting polymer (polyaniline) and a polymeric perfluorinated sulfo cationite (Nafion, MF-4SK). The composite formation involves two steps. First, the monomer (aniline) is intercalated into the solid-cationite matrix probably with the formation of a template phase, after which postintercalation polymerization of the template occurs.

Electrocatalytic oxidation of formic acid on a glassy-carbon-Nafion-polyaniline-palladium nanoparticle electrode: Effect of the polymer matrix state

The rate of decomposition of formic acid on a glassy-carbon-Nafion-polyaniline-palladium nanoparticle composite as a function of the state and amount of polyaniline in the composite is studied.

Composite Polyaniline/MF-4SK Membranes: A Chemical Template Synthesis and the Sorption and Conduction Properties

The sorption and hydrophilic properties of composite membranes PAN/MF-4SK, obtained by a chemical template synthesis, are studied. The synthesis is performed in static and dynamic conditions for perfluorinated sulfo-cationite membranes MF-4SK in 0.01 M aniline solutions in 0.5 M H2SO4 and 0.01 M FeCl3 in 0.5 M H2SO4. The aniline sorption and polymerization kinetics is studied by conductimetry, radioisotope, and optical methods. The polymerization rate is found to depend on the oxidant concentration and the sequence of the membrane saturation with aniline. An increase in the intensity of the color of a composite film, which depends on the balance between the quinoimine, amine, and radical-cation fragments in the perfluorinated matrix, does not lead to any substantial changes in the moisture content or the ac electroconductivity. Implanting polyaniline chains into the perfluorinated matrix presumably leads to a molecular reorganization of water at the expense of a change in its association at the point where redox fragments of polyaniline converge with side segments of the template matrix.

Synthesis and properties of composite polyaniline-nafion films on glassy carbon

Information on the synthesis of a polyaniline film on glassy carbon covered with a Nafion film is obtained. The effect of electrochemical synthesis conditions on the process is studied. The relationship between these conditions and properties of obtained composite polyaniline–Nafion films is revealed.

Electrochemical behavior of single-carbon organic compounds on a composite nafion-polyaniline-palladium particle electrode in acid solutions

Electrooxidation and adsorption of formic acid, methanol, and formaldehyde at a composite electrode and the influence of the composite formation conditions on these processes are studied.

Studies of chemical stage of synthesis of electroactive composite based on poly-o-phenylenediamine and graphene oxide

Formation of an electroactive composite based on graphene oxide and poly-o-phenylenediamine (PPD) was studied. Electron absorption spectra were used to confirm formation of a strong chemical bond at a prolonged contact of unreduced graphene oxide on a conducting support (glassy carbon, SnO2) and o-phenylenediamine monomer solution. Here, graphene oxide is partially reduced and oxidation and partial polymerization of o-phenylenediamine starts. It is shown that electrochemical oxidation of the obtained composite under the conditions of cyclic voltammetry results in the further polymerization of o-phenylenediamine bound to graphene oxide; here, reduction of graphene oxide continues, and at much lower cathodic potentials than in the absence of o-phenylenediamine. Morphology of the obtained composite was studied using the AFM technique. PPD embedded into the composite structure does not allow nanosheets of reduced graphene oxide (RGO) to corrugate and imparts the morphology of the composite the shape of globules with a clearly pronounced structure. As a result, the RGO–PPD composite was obtained that demonstrated pronounced electroactivity in a wider range of potentials than in the case of nonmodified PPD.

Cyclometalated ruthenium complex as a promising sensitizer in dye-sensitized solar cells

Ruthenocycle bis(4,4′-dicarboxy-2,2′-bipyridine)(2-phenylpyridine-2C,N)ruthenium(II) hexafluorophosphate was used as a sensitizer in a dye-sensitized solar cell (DSSC) based on nanocrystalline TiO2, which was applied onto a conducting substrate. Its electrochemical and spectral characteristics were studied. It was found that, when the DSSC was illuminated with visible light of power 35 mW/cm2, the short-circuit current density was 11.6 mA cm−2 and the open-circuit voltage was 0.49 V. The efficiency (η) of DSSC at a fill factor of 45% was 7.1%. Using the method of modulation spectroscopy of photocurrents and photopotentials, the life time and transit time of electrons were found to be 7 and 5 ms, respectively, and the diffusion coefficient of electrons was found to be 10−5 cm2 s−1. Comparing the life and transit times of electron, it was concluded that the photogenerated electrons had time to reach the conducting substrate during their life time.

Synthesis and Properties of Composite Polyaniline–Nafion Films on Platinum

Information on the synthesis of a polyaniline film on platinum covered with a Nafion film is obtained. The effect of electrochemical conditions on the synthesis is studied. The relationship between these conditions and properties of obtained composite polyaniline–Nafion films is revealed. It is established that on platinum covered with a Nafion film in certain electrochemical conditions in a polyaniline solution there occurs the formation of a composite polyaniline–Nafion film. The polyaniline in the film mainly retains its individual properties. It is demonstrated that the mechanism of the synthesis of polyaniline in the composite film substantially differs from that in the case of the formation of a film on platinum.

Coordination compounds as the precursors for preparation of nanosized platinum or platinum-containing mixed-metal catalysts of oxygen reduction reaction

Nanosized mixed-metal platinum-iron, platinum-anganese and platinum-nickel catalysts supported on highly dispersed carbon black are synthesized by using the corresponding metal complexes with the atomic metal ratio of 1:1. The obtained catalysts are characterized by X-ray phase diffraction and scattering analysis, electron dispersion analysis, scanning and transmission electron microscopy. Thin film rotating disk electrode technique was used to study kinetic parameters of the oxygen reduction reaction at these catalysts. It has been demonstrated that electrochemical activity of the prepared catalysts is comparable to that of a commercial E-Tek platinum catalyst. The membrane electrode assembly (MEA) with the synthesized platinum-iron catalyst was tested in a laboratory hydrogen-air fuel cell setup at room temperature. It was shown that the power performance of this MEA was twice better than that of a MEA on the base of a commercial Pt/C E-Tek catalyst.

Immobilization of phthalocyanines in conducting polymers. Polyaniline-copper tetrasulfophthalocyanine

Interaction between the anilinium cation and copper tetrasulfophthalocyanine anion (CuTSPc) was studied in an aqueous sulfuric acid solution using electronic absorption spectra. It was shown that up to 0.15 M aniline could be introduced into the solution at the dye concentration of 10−3 M, after which a solid deposit of a complex (salt) between the anilinium cation and copper tetrasulfophthalocyanine anion started precipitating rapidly. The effect of the dye on the kinetics of aniline polymerization on conducting glasses and on the properties of the polymer obtained was studied. It was found that phthalocyanine accelerates electropolymerization of aniline and is immobilized within the polymer matrix. It was shown that the self-catalytic synthesis mechanism characteristic of polyaniline is also preserved in the case of the composite of polyaniline-copper tetrasulfophthalocyanine.