S. A. Baskakov

Photoreduction of graphite oxide

The photoreduction of graphite oxide (GO) films and solutions by UV light was studied. The electrical resistance of a GO film decreases upon irradiation by more than an order of magnitude. The threshold of photoreduction was determined to be 3.2 eV. The photoreduction is accompanied by an increase in absorption in the visible spectral region, and the CO, CO2, O2, and H2O molecules were found in the gas phase above the irradiated GO film.

Carbon nanomaterial produced by microwave exfoliation of graphite oxide: new insights

We present detailed characterization of graphene-like material obtained through microwave stimulated exfoliation of graphite oxide (GO). Properties of this material were studied by multiple techniques including, among others, X-ray photoelectron spectroscopy, mass-spectroscopy, infrared and Raman spectroscopy, scanning electron microscopy and broadband dielectric spectroscopy. Specific surface area and volume of microwave exfoliated graphite oxide reached 600 m2 g−1 and 6 cm3 g−1, respectively. It is shown that during such an explosive reduction process the sample emits CO2, CO and H2O and, in some cases, SO2 gases. The resulting reduced material exhibits IR spectra similar to that of graphite and a dc-conductivity of 0.12 S cm−1.

Photoreduction of graphite oxide nanosheets with vacuum ultraviolet radiation

Films of graphite oxide nanosheets have been prepared by deposition from an aqueous alcohol emulsion onto a Teflon FEP substrate. The behavior of the films exposed to monochromatic vacuum UV radiation at a wavelength of 123.6 nm has been studied. It has been found that irradiation decreases the water content and the amount of hydroxyl (OH) groups and increases the concentration of double bonds in the film. At the same time, irradiation does not decrease the amount of C=O groups in the carboxyl and ketone moieties.

A comparative study of graphene materials formed by thermal exfoliation of graphite oxide and chlorine trifluoride-intercalated graphite

Graphene 3D materials GM1 and GM2 obtained by explosive exfoliation of graphite oxide and graphite intercalated with chlorine trifluoride, respectively, have been studied by elemental analysis, X-ray photoelectron spectroscopy, mass spectrometry, infrared and Raman spectroscopy, and scanning electron microscopy. The specific surface area, the pore size, and electrical conductivity of the materials have been measured. A comparative study has shown that the gas mixture produced during the preparation of GM1 is less hazardous than that in the case of GM2. However, GM2 exhibits a higher conductivity and a larger size of graphene crystallites. The feasibility of isolation of a suspension of graphene nanosheets from the test 3D materials has been demonstrated. Possible applications of these materials are discussed.

Effect of ultrasound treatment of C60 solutions on the crystalline structure of precipitated fullerite

The structure of fullerite precipitated from solutions of C60 in toluene, chlorobenzene, and 1,2-dichlorobenzene by adding isopropanol was studied. It was demonstrated that, irrespective of the nature of the solvent, the parameter of the fcc lattice of precipitated fullerite decreases markedly when the process occurs in the presence of a ultrasound field. No effect of ultrasound sonication on the size of the precipitated crystallites was observed.

In the chase of mixed halofullerenes: Remarkable transformation of C60Cln (n = 6, 8, 12, 14) to C60Br24

Abstract Chlorofullerenes C60Cl n (n = 6, 8, 12, 14) were found to react with bromine yielding C60Br24 as a single product. No intermediates containing both bromine and chlorine atoms attached to the cage were detected in the course of transformation.

An NMR, DSC, and IR spectroscopy study of the composite formed during low-temperature postradiation polymerization of C2F4 in the presence of a 3D graphene material

By solid-state magic angle-spinning nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), and IR spectroscopy, polytetrafluoroethylene (PTFE) samples obtained by low-temperature (T = −196°C) postradiation polymerization of tetrafluoroethylene (C2F4) and C2F4 mixtures with a 3D graphene material formed by the microwave exfoliation of graphite oxide films (MEGO) have been investigated. It has been shown that the melting point of PTFE in the PTFE-MEGO composite is 332.5°C, which is 8.8°C above the melting point of pure PTFE obtained under the same conditions. According to the measured values of specific enthalpy of melting ΔHm (51.5 and 45.4 J/g), the degrees crystallinity (xc) of 0.63 and 0.55 have been calculated for the pure polymer and the composite, respectively. It has been also found that none of the PTFE-containing samples examined has terminal CF3 groups typical of PTFE prepared by conventional suspension polymerization.

Composite materials based on reduced graphene oxide and polyaniline. Composition, morphology, electrochemical properties

It is shown that electrochemical characteristics of electrochemically synthesized composite materials (CMs) based on reduced graphene oxide nanosheets (RGONS) and polyaniline (PAni) depend considerably on the composition of CMs. Drastic variation of specific electrochemical capacity Cs in CMs is observed in the range of PAni content of 30–75 wt %. In the same range of compositions, practically full RGONS surface coverage by the synthesized PAni is observed, as shown by SEM.

Controlled electrosynthesis of polyaniline on branched surface of reduced graphene oxide

Electrochemical synthesis is used to obtained a number of composite materials (CMs) consisting of different layers of reduced graphene oxide nanosheets (RGONS) and polyaniline (PAni) coatings of different thickness synthesized on these layers. Ranges of PAni–RGONS weight content, at which the maximum values of capacity are reached, are determined. CM samples with high C values demonstrated higher stability in the course of electrochemical studies.

New data on the composition of products of ultrasonic irradiation of graphite in N-methylpyrrolidone

It has been found that ultrasonic irradiation of graphite in N-methylpyrrolidone is accompanied by the formation of polymer nanoparticles. These particles form aggregates with n-layered graphene particles, the formation of which prevents graphene particles from precipitation during centrifugation.