[Show abstract][Hide abstract] ABSTRACT: 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.
High Energy Chemistry 11/2013; 47(6). · 0.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Oxidized fullerite was obtained by heating a fullerite sample intercalated with oxygen, (O2)0.44C60, up to 300 degrees C. Orientational phase transitions in the oxidized fullerite are studied using differential scanning calorimetry (DSC) and have been found to possess a specific enthalpy whose value is lower by 25% than in the initial (O2)0.44C60 sample. In order to find possible reasons for hindrance to the buckyball rotations, we performed optimizations of defect buckyball fullerenes C60-n with different distributions of vacancies along with the dimers C60-n-C60-n and C60-C60-n for n = 1-4 using density functional theory with generalized gradient approximation. We found that the dimerization energy ranges from 1.07 eV (C58-C58) to 6.56 eV (C56-C56) and from 1.81 eV (C60-C58) to 4.29 eV (C60-C56), respectively. The formation of such dimers, which could in addition interact with defect buckyball cages and form larger aggregates, is to be related to the lowering of the orientational transition enthalpy.
Journal of Nanoscience and Nanotechnology 03/2011; 11(3):1887-96. · 1.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nonpyrophoric tungsten powders with an average particle size of about 30 nm were obtained by pyrolysis of tungsten hexacarbonyl
in a flow of microwave discharge nitrogen plasma. It is found that these powders are stable in air up to 300°C. The reason
for such stability is that the structure of powder particles is of the core-double shell type, in which the metal core is
covered with an oxide film approximately 1 nm in thickness, coated in turn with roentgenoamorphous layer consisting of carbon,
oxygen, and nitrogen atoms. It is also established that the powders under investigation mainly release carbon oxides (CO and
CO2) and water into the gas phase upon heating in vacuum. Among the molecules present in the gas phase in small concentrations,
nitrogen monoxide (NO) and formaldehyde (H2CO) are worth mentioning apart from C1–C3 hydrocarbons.
[Show abstract][Hide abstract] ABSTRACT: 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.
High Energy Chemistry 01/2011; 45(1):57-61. · 0.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mass-spectrometric investigation of gases produced by heating in vacuum fluorinated single-wall nanotubes (with fluorine content of 25 mass %) which have been kept in air was carried out. It has been shown that nanotubes, which are preliminary, treated in vacuum at 23 °C, being heated in the temperature range from 23 to 100 °C produce generally H2O, CO and CO2. The gases containing fluorine appear in the range from 100 to 150 °C. In the range of 150–300 °C the mixture of disintegration products contain molecules COF2, and in the range of 300–400 °C mostly CF4 and C4F6 appear.
International Journal of Hydrogen Energy. 01/2011;
[Show abstract][Hide abstract] ABSTRACT: Gases evolved on heat-treatment of intact fullerite C60, single-walled (SW) and multi- walled nanotubes (MWNTs) and chemically modified carbon nanomaterials (deuterofullerites C60Dx, hydrogenated SWNTs and fluorinated MWNTs) are studied by mass spectrometry. INTODUCTION Physical and chemical sorption of small molecules by high specific surface area carbon nanomaterials readily occurs during their synthesis, purification and storage. Trapped molecules can affect material properties. For example, gas desorption from carbon nanotube field emitters leads to inferior performance and shorter lifetime of vacuum electronic tubes. Adsorbates on carbon nanomaterials can reduce the capacity of hydrogen storage devices. Therefore, the gas composition and quantity evolved by carbon nanostructures at elevated temperatures merits critical evaluation. The paper presents data on evolved gas composition, which occurred upon heat treatment of fullerites, single-walled and multi-walled nanotubes. Variation of sorption properties upon chemical modification of nanostructures is discussed.
[Show abstract][Hide abstract] ABSTRACT: The composition of gases over a graphite oxide is found to depend on the temperature with CO2 being the main component with a range of 23–460 °C. In the temperature range of 150–230 °C, where the most intense yield of gases was observed, CO forms in small amounts. CH4 and CH2O were produced at temperatures below 230 °C, O2 was observed at 150–300 °C, while the complex H2OH·COOH was produced at temperatures above 150 °C. When films composed of graphite oxide nano-sheets were exposed to UV radiation, CO2, CO, H2O, and O2 were produced.
Chemical Physics Letters 08/2010; 498(4-6):287-291. · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fullerite with cavities containing dichlorobenzene (DCB) and isopropyl alcohol (IPA) molecules was prepared by the addition
of IPA to a solution of fullerene C60 in DCB. On heating in vacuo fullerite evolves IPA, and the temperature increase to 200—350 °C results in the evolution of acetone. No products of DCB
conversion were observed. Possible products of the interaction of 60 with two IPA molecules were calculated by the quantum
chemical method. New data on the fullerite structure were obtained by transmission electron microscopy X-ray powder diffractometry,
mass spectrometry, IR spectroscopy, and other methods. One of the possible mechanisms of the reaction IPA → acetone was considered.
Key wordsfullerite C60
-isopropyl alcohol-dehydrogenation of alcohol-X-ray phase analysis-IR spectroscopy-mass spectrometry
Russian Chemical Bulletin 08/2010; 58(4):758-764. · 0.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Dependence of gassing upon decomposition of 1 M LiClO4 electrolyte in γ-butyrolactone (γBL) with various contents of water (0.008 and 0.2% w/w) at a lithium electrode on the current
density of charging was studied. Quantum chemical modeling of γBL interaction with lithium surface was performed. The initial
stage of γBL decomposition is the formation of a surface organolithium compound, which is hydrolyzed in the subsequent reactions
Key words-γ-butyrolactone, lithium electrode-lithium nitride-gassing-quantum chemical modeling-density functional theory
Russian Chemical Bulletin 03/2010; 59(3):510-516. · 0.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A (O2)
C60 sample with a high content of oxygen (x ≥ 0.4) and free of technological solvent impurities was obtained by precipitation from solution. For the first time, the
results of the determination of the x coefficients using 13C NMR and elemental analysis were compared. It was shown by Raman spectroscopy, mass spectrometry, and NMR that the inclusion
of oxygen into fullerite was accompanied by a decrease in the frequency of O=O stretching vibrations by no less than 12 cm−1 compared with gaseous O2. Nevertheless, oxygen exists in the molecular form in (O2)0.4C60 and is released in the form of O2 as the sample is heated to 373 K. The number of oxygen molecules occupying octahedral pores closets to the fullerene molecule
takes on all the possible values, from 0 to 6. At room temperature, the (O2)
C60 sample lost oxygen much more slowly than similar products prepared by diffusion saturation of pure fullerite with oxygen.
Russian Journal of Physical Chemistry B 01/2010; 4(4):543-547. · 0.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The mass spectra of the dissociative electron-impact ionization products of telomers formed upon the radiation-chemical telomerization
of tetrafluoroethylene in acetone were measured over the range of m/z from 1 to 204. The most intense bands at m/z = 43, 51, and 57 were attributed to the CH3CO+, CF2H+ and CH3COCH2+ cations—the main dissociation products of the H(C2F4)
CH2COCH3 telomers. The telomer composition was consistent with a radical telomerization mechanism, in which chain growth and chain
transfer are due to the formation of the CH3COCH2· radical. Based on published data supplemented with quantum-chemical calculations, the enthalpies of formation of the radicals
(n = 2–8; R = H, CH3, CH3CO, and CH3COCH2) were tabulated. The formation of telomers with the same terminal groups is consistent with thermodynamic data and a polymerization
mechanism in which the chain growth reaction is diffusion-limited and the chain transfer reaction is activated hydrogen-atom
High Energy Chemistry 01/2010; 44(6):449-454. · 0.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have obtained fullerite intercalated with CH2F2 by precipitation of C60 from the solution in 1,2-dichlorobenzene saturated by CH2F2. The chemical composition was identified as (CH2F2)xC60 (x = 1.03 ± 0.21). The fcc lattice parameter (14.28 Å) was found to increase significantly for (CH2F2)C60 in comparison with that for pristine C60 (14.16 Å). The IR absorption peak attributed to the stretching vibration of the C–F bond in (CH2F2)C60 was 30 cm–1 shifted to lower wave numbers in comparison with the gas phase CH2F2 spectrum.
physica status solidi (RRL) - Rapid Research Letters 12/2009; 3(2):43-45. · 2.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fullerite with the bulk formula ArxC60, where 0.60 < x < 0.75, was synthesized by precipitation from a mixture of argon-saturated solutions. The fcc unit cell parameter in the
sample was 1.422 nm; the orientational phase transition (OPT) temperature was 247 K. These values noticeably differ from the relevant parameters of undoped fullerite (1.416 nm and 260 K, respectively). Heating accompanied by argon evolution restores
the fullerite C60 structure.
[Show abstract][Hide abstract] ABSTRACT: The optimum conditions for the fluorination of single-walled carbon nanotubes (SWCNT) in the atmosphere of gaseous fluorine
with the nanotube structure remaining intact up to a stoichiometry of CF
, x ∼ 0.5 were determined. The kinetics of fluorination was examined. The fluorinated SWCNTs were characterized by various methods,
including transmission electron microscopy, measurements of specific surface area and accessible internal volume, NMR spectroscopy,
IR spectroscopy, X-ray absorption and photoelectron spectroscopies, thermal stability, and analysis of gaseous products by
mass-spectrometry. The structure of fluorinated SWCNT was preserved up to brutto-composition CF0.5 but degree of fluorination of SWCNT bundles was decreased with distance from the SWCNT surface to its core. Such a decrease
becomes evident at ∼1.5 nm distance. It means that the degree of fluorination depends on the degree of its dispersion.
[Show abstract][Hide abstract] ABSTRACT: C60 fullerite intercalated by acetylene was synthesized for the first time and studied by a number of experimental methods. It is found that the intercalate obtained corresponds to (C2H2)0.23C60 and possesses an fcc lattice. We also performed optimizations of the C60+C2H2 complex using density functional theory with the generalized gradient approximation. Two complexes were studied corresponding to acetylene chemisorbed by or inserted inside C60. Both complexes do correspond to local minima that are lower than the dissociation limit to C60 and C2H2. However, these complexes were not observed in experiment most likely because of their high energy barriers.
Chemical Physics Letters 01/2009; 483:115-119. · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Processes induced by the heating of C60 fullerite intercalated by oxygen are analyzed using mass-spectrometry, thermogravimetry, differential scanning calorimetry, and electronic spin resonance (ESR) techniques. It was found that the primary gas produced at the heating temperatures below 100 °C is molecular oxygen while at higher temperatures up to 200 °C carbon mono- and dioxides were also observed. The heating was accompanied by an appreciable increase in the ESR signal intensity. In order to gain insight into the oxidation products that are capable to contribute to the ESR signal, we performed all-electron density functional theory computations for C58On (n = 0−4), C59On (n = 0−2), and endohedral complexes O2@C58, O2@C59, and O2@C60. It is found that the triplet states of C58, C58O3, O2@C58O2, O2@C58, and O2@C60 are lower in total energy than the corresponding triplet states. The singlet and triplet states of C59, O2@C59, and C602− are nearly degenerate in total energy. Thus, there are a number of species that can be responsible for the paramagnetic behavior observed in the oxidized fullerene.
Journal of Physical Chemistry C - J PHYS CHEM C. 07/2008; 112(32).
[Show abstract][Hide abstract] ABSTRACT: Fullerite C60 with intercalated CH2F2 (Freon-32) was prepared for the first time. The sample was studied by elemental analysis, X-ray powder diffraction, mass
spectrometry, and IR spectroscopy. The composition of the sample was found to be (CH2F2)C60. The sample had a face-centered cubic lattice with the lattice parameter (1.4284 nm) much larger than that of pure fullerite
(1.416 nm). The gas released from the sample during heating in a vacuum to 450°C largely consisted of initial Freon (mass
spectrometry data); no Freon destruction products were observed at this temperature. The C-F stretching vibration frequency
(1058 cm−1) was shifted in (CH2F2)C60 by 30 cm−1 toward lower wave numbers compared with the gas phase. The absorption bands at 1182 and 1428 cm−1 (IR active modes (F
) of high-symmetry (I
) C60 molecules) did not change their positions in the intercalate.