V. D. Pokhodenko

New polyaniline–MoO3 nanocomposite as a result of direct polymer intercalation

A new nanocomposite based on polyaniline and MoO3 is prepared via direct intercalation of conducting polymer macromolecules. The method of preparation allows material to be obtained with peculiar electric and electronic properties.

Preparation of graphene oxide by solvent-free mechanochemical oxidation of graphite

Graphenes with different oxidation degrees are prepared by ultrasound assisted aqueous exfoliation of solvent-free mechanochemically treated graphite in the presence of solid oxidants, under comparatively mild conditions without using aggressive concentrated acids.

New hybrid guest–host nanocomposites based on polyaniline, poly(ethylene oxide) and V2O5

New hybrid guest–host nanocomposites based on V2O5, in the interlayer galleries of which there are simultaneously the macromolecules of two polymers poly(ethylene oxide) and polyaniline, one being an ion-conducting polymer and the other electron-conducting, are obtained. The preparation of such ternary nanocomposites is realized by the insertion of polyaniline into the structure of the preliminary prepared, soluble, two-component poly(ethylene oxide)–V2O5 nanocomposite either by intercalative polymerization of aniline in situ, or by direct intercalation of conducting polymer macromolecules. Intercalation of the polymers is confirmed by physicochemical analysis. The presence of two polymers with different types of electrical conductivity inside V2O5 results in an improvement of the charge capacity and stability during charge–discharge cycling.

Energetics of electron processes in semiconductor photocatalytic systems

The energetics of electron processes in photocatalytic systems based on dispersed semiconductors, their nanocomposites and heterostructures are examined. Methods for the approximate estimation and quantitative determination of their energetic characteristics are evaluated and energy diagrams of photocatalytic systems based on semiconductor nanocomposites and their heterostructures are plotted. Analysis of the diagrams permits the elucidation of the nature of their photocatalytic effects in redox reactions.

Improved dispersant-free liquid exfoliation down to the graphene-like state of solvent-free mechanochemically delaminated bulk MoS2

Molybdenum disulfide (MoS2) was recently found to exhibit an indirect-to-direct gap transition when its thickness is reduced to a single S–Mo–S trilayer sheet, which opens up opportunities for a range of novel optoelectronic applications. Here we first report the possibility of dispersant-free efficient liquid exfoliation down to the graphene-like state of solvent-free mechanochemically delaminated bulk MoS2. The graphene-like, single-sheet structure of MoS2 nanoparticles in the dispersions is confirmed by mutually complementary experimental methods. The proposed approach essentially improves the known liquid exfoliation method based on the ultrasound disintegration of bulk MoS2, because the proposed mechanochemical treatment of the initial bulk MoS2 could provide 100% yield of the single-sheet nanoparticles without the use of dispersants.

Ultrasound-free preparation of graphene oxide from mechanochemically oxidized graphite

We propose an ultrasound-free preparation of graphene oxide using spontaneous exfoliation of specifically synthesized graphite oxide in water for the first time. Graphite was mechanochemically oxidized by KMnO4 in the presence of a stoichiometric amount of sulfuric acid. The shear stresses generated during the oxidation lead to primary delamination of the graphite oxide particles and in combination with the presence of the surface oxygen-containing functional groups facilitate their further exfoliation in water without the use of ultrasound disintegration. The synthesized graphene oxide luminesces in the blue region of the spectrum.

New electrolytes and polymer cathode materials for lithium batteries

Abstract Novel aprotic electrolytes, based on propylene carbonate and γ-butyrolactone compositions with a variety of added organic compounds (polyethers, quinones, aromatic hydrocarbons) have been devised. The electrolytes configured have been shown to be able to form protective, ion-conductive films on the surface of lithium and to improve dramatically the operational characteristics of lithium chemical cells. Processes for synthesizing novel composites, based on conducting organic polymers (polyaniline, polypyrrole, etc.) and transition metal (V 2 O 5 , TiS 2 ) binary compounds-challenging cathode materials for secondary lithium batteries have been developed.

Green Chemistry and Modern Technology

The basic principles, approaches, and early achievements of green chemistry are considered. The definition of green chemistry as a branch of chemistry that studies the laws of passing of chemical reactions and the properties of substances participating in such reactions, with the aim of acquiring basic knowledge that provides a basis for designing chemical technologies that eliminate (sharply curtail) the use and production of materials that pose a risk to the environment.

Effect of the electrolyte nature on the electrochemical doping of poly-3-phenylthiophene

Abstract Electrochemical p- and n-doping of poly-3-phenylthiophene in organic aprotic bipolar solvents was investigated. It has been established that potential of polymer p-doping is diminishing proportionally to lowering of solvent molecules dipole moment due to ion–dipole interaction of ClO 4 − doping anion with solvent molecules. Potential of polymer n-doping in the presence of Et 4 N + and Bu 4 N + cations is determined by solvation of anion radical fragments of polymer. Good linear dependence between the potential of polymer n-doping and Dimroth–Reihardt solvent parameter was obtained. It has been shown that the electrochemical n-doping of poly-3-phenylthiophene by Li + cations could be realized in acetonitrile only and its value depends on crown-ether nature because of formation of both complexes with Li + and stable solvates with acetonitrile.

Nanosized effects in composites based on polyaniline and vanadium or iron oxides

It has been established by means of elemental analysis, X-ray diffraction, IR and optical spectroscopies, cyclic voltammetry and EPR that, due to the nanostructure, the composites based on polyaniline (PAn) and on vanadium or iron oxides display consistent specific spectral, electrochemical, magnetic properties which are associated with intermolecular interaction with charge transfer between conducting polymer and inorganic component of the composites and with formation of the united electronic system. The nanosized effects in both composites explored possess similarity as well as distinctions. While in the PAn–V2O5 nanocomposite direct interaction of the polyaniline macromolecules, intercalated in the V2O5 galleries, with V5+ ions takes place, resulting in charge transfer, the charge transfer between polyaniline and Fe3O4 particles of the PAn–Fe3O4 nanocomposite is motivated by the fact that during the synthesis of the composite the Fe3O4 particles in the starting sol and in the reaction medium carry a certain surface charge which they retain in the composite, thus acting as peculiar extra dopants for macromolecules of the conducting polymer.