A thermal-lens spectrometer implementing back-synchronized detection technique with a mode-mismatched optical scheme was constructed. Steady-state and transient signals of thermal-lens spectrometry are used to characterize concentration parameters of aqueous fullerene dispersions (AFDs) at the level of 10⁻⁷ – 10⁻⁵ M and to assess thermophysical properties of AFDs. The detection limits of fullerenes in AFDs are 100 nM for C₆₀, 80 nM for C₇₀ and C₇₈ – C₈₈, and 60 nM for Y@C₈₂, which are 20-fold lower than for spectrophotometry. Suitable precision of measurements of thermal diffusivity and thermal effusivity for AFDs is shown.

Thermal-lens spectrometry was used to characterize thermal diffusivity and thermal conductivity of aqueous nanodiamond dispersions at the level of mg/mL, accompanied by heat capacity, density, and viscosity measurements and modelling. The data from thermal lensing corresponding to thermal equilibrium show 3 – 7 % increase in thermal conductivity of the studied dispersions, show good precision and agree with the existing data.

We present the results from our investigation of the structure and composition of microcrystalline diamonds obtained by sintering at high pressures and at high temperatures of detonation nanodiamond particles. Using XPS, XAS and photoluminescence spectroscopy, we found that the surface’s chemical composition and a defects structure of microcrystalline diamonds significantly differ from the initial detonation nanodiamonds. This indicates the essential transformation of structure and composition of initial detonation nanodiamonds particles during the formation of single crystals at high pressure and temperature.

The aspects of phase and size stability of surface fluorinated nanoscale diamond powders during their treatment under conditions of high pressures and high temperatures (HPHT) are considered. In the studied powder, fluorine is covalently bonded to diamond particles, replacing the other functional groups on their surface. In this case, under pressure of 8.0 GPa the transition of 10-nm-size diamond nanoparticles into a graphene layered carbon forms does not occur up to temperatures of 1700 ◦C, and their size does not change. The addition of submicro-sized aluminum powder to fluorinated nanodiamond results in the fast growth of particles to a micrometer size range. The observed unprecedented enlargement of nanodiamonds to micro-sized crystals is explained by occurrences of Wurtz-type reactions in the C–Al–F system which activate the formation of new interfacial carbon–carbon bonds between nanoparticles and their coalescence under HPHT conditions.

The decomposition kinetics of the fullerene dimers and photo-oligomers was studied at elevated temperature by Raman scattering. The polymeric content decreases exponentially with the thermal treatment time while the decay time constant decreases at higher temperatures. The activation-type behavior is well described by the Arrhenius law that gives the activation energy EA = (1.71 ± 0.06) eV/molecule for the dimers and EA = (0.87 ± 0.06) eV/molecule for the C60 photopolymer.

The crystal structure of the molecular donor-acceptor complex {Cd(Et2dtc)}₂·DABCO ·C₆₀·(DABCO)₂ (where dtc is dithiocarbamate, DABCO is diazabicyclooctane) was studied by X-ray diffraction (XRD) at high pressure using the diamond anvil cell (DAC) technique. The pressure dependence of lattice parameters is smooth and monotonous, the bulk modulus and its derivative B₀ = 7.94 GPa and B^t = 9.65 are close to those of pristine C₆₀. Raman spectra of the complex measured at λ_exc = 532 nm showed a peculiarity in the pressure dependence of A_g(1), A_g(2), H_g(1) and H_g(7) modes of the C₆₀ molecule near 2 GPa. This peculiarity relates to pressure-assisted photopolymerization in the fullerene layers which is suppressed in Raman measurements at λ_exc = 785 nm showing smooth pressure behavior of phonon modes.

Microgravity creates favorable conditions to reduce dislocations and grain boundaries density in growing crystals due to absence of close contact with the ampoule walls and absence of plastic deformation of the crystal under its own weight. For improvement of the fullerite C₆₀ crystal growth technology before the scheduled space experiments on the ISS the growing of the high purity grade fullerite C₆₀ crystals with the sufficiently high structural perfection were carried out on the Earth from the C₆₀ vapor in sealed quartz ampoules (pre-evacuated to the pressure of 10−3 Pa) at temperatures in the evaporation zone ranging from 560 – 610 ◦C with a temperature gradient between the evaporation and deposition zones of 3 – 10 K/cm within 72 h. The grown single crystals had a size of ∼ 5 × 5 × 5 mm and habitus corresponding to the fcc lattice. IR spectroscopy shows the high purity fullerite C₆₀.

The ultrasound-assisted solvent-exchange technique for aqueous fullerene dispersions (AFD) of C60 (10−4 – 10−6 M) have been improved for high-yield synthesis, thereby achieving AFDs with total recovery over 90 %. Using ICP-AES, HPLC-UV, HGC-MS, the elemental and residual organic compounds have been estimated as not exceeding 3 ppm. The possible structure of fullerene clusters in AFD was assumed as {n[C60]mC6H5COO−(m − x)Na+}xNa+.

The article continues the development of the investigations, presented in particular in the cycle of articles, devoted to the synthesis, identification and investigation of physical-chemical properties of water soluble derivatives of light fullerene C60, such as: complex esters of dicarboxylic acids (malonates, oxalates); poly-hydroxylated forms (fullerenols); amino-acid derivatives (argenine, alanine). The investigation of the excess thermodynamic functions, to the best of our knowledge, has, until now, not been provided, except for two original works [Matuzenko M.Yu., Tyurin D.P., et al. (2015); Matuzenko M.Yu., Shestopalova A.A., et al. (2015)].

In this study, with the use of laser Raman spectroscopy the significant difference in intermolecular interactions of detonation nanodiamonds with hydrophilic and hydrophobic surface groups in aqueous solution of surfactants was observed. It was found that at low concentrations of sodium octanoate (before the micelle formation) the weakening of hydrogen bonds by nanodiamonds has a different dynamics for hydrophobic and hydrophilic nanodiamonds. However, with the addition of surfactants, this effect gradually decreases for both types of nanodiamonds and ends after the formation of micelles. Such effects are explained by the “shielding” effect of surfactant molecules surrounding nanodiamond particles.

We consider isotopic effects on the photoluminescence of recently discovered germanium-vacancy (GeV−) color center in diamond produced by the high-pressure high-temperature (HPHT) treatment. It was demonstrated that the influence of isotopic composition on the position of zero-phonon line (ZPL) and its first vibronic peak (local vibrational mode, LVM) provides valuable information on the electronic and structural properties of this center.

We report photoluminescence studies of micro- and nano-sized diamonds with NV⁰, NV⁻ and SiV⁻ centers under hydrostatic pressure up to 50 GPa. Diamonds have been obtained by high-pressure high-temperature (HPHT) treatment of metal-free growth systems based on mixtures of hydrocarbon, fluorocarbon, and silicone-containing organic compounds.

We investigated the formation of nanostructures on the surface of rolled thin platinum foils at the heating and “tension–compression” cycles in ultrahigh vacuum. The surface was characterized by LEED, AES, AFM, optical microscopy and micro Raman spectroscopy (MRS). Quantitative characterization of the surface relief was made by fractal analysis. About 95 % of the Pt foil surface was made by close packed Pt (111) face with unidirectional rippled multi-scale relief. Under the applied tension, changes in the LEED and AFM patterns were observed and it was found that, preceding the formation of the main crack, the surface becomes difractionally disordered with relief fractality turning to an isotropic one. Moreover, at the foil surface, near the clips of the sample holder (about 5 % of the surface area), the surface groups of micro crystals with sizes about 10 µm were observed which were identified by MRS as microdiamonds and diamond-like carbon.

In this paper, we present the results of quantum-chemical modeling for atomic hydrogen adsorption on the C(100)–(2 × 1) diamond surface containing a “boron + monovacancy” complex defect. We also provide a comparison of the energy characteristics of adsorption (activation energy and adsorption heat) for an ordered diamond surface, graphene surface, and a surface containing a “boron + monovacancy” complex defect.

In this study, the interaction between DNA and the surface of detonation nanodiamonds and nanodiamonds with NV centers is investigated, and the quantitative parameters of this interaction are calculated. The influence of interaction of DNA with nanodiamonds on the fluorescent properties of nanodiamonds is established. A correlation was found between the efficiency of DNA interaction with the surface of the detonation nanodiamonds and the changes of their fluorescence: the more DNA bonds with the nanodiamond surface groups – the stronger the fluorescence of detonation nanodiamonds increases in water.

We report low temperature (80 K) photoluminescence studies of microcrystalline diamond with germanium-vacancy (GeV) centers under hydrostatic pressure up to 6 GPa. Powders of Ge-doped diamond crystals were synthesized from hydrocarbons at high-pressures and high- temperatures. Due to the high quality of the samples, we were able to resolve the distinct quadruplet structure of the zero-phonon line (ZPL) of the GeV center already at 80 K and to trace it up to ∼ 6 GPa. The pressure dependence of ZPL was found to be linear with the pressure coefficient dE/dP = 3.1 meV/GPa, which is nearly 3 times higher than that for the isomorphic SiV− center. The experimentally observed pressure coefficients of GeV−, NV− and NV0 centers are compared with results of ab-initio DFT calculations, using Quantum ESPRESSO software package.

Basing on the hypothesis of the emission molecular orbitals (EMO) existence in single-walled carbon nanotubes generated by in-plane-electron conjugation of p-electrons, we studied influences of adsorbate (H2 and F2) nature on characteristics of electrons field emission from open single-walled ultrashort carbon nanotubes of chirality (n, 0). It has been shown that the adsorption of admixture atoms on the graphene surface increases the work function of the electron, moreover more considerable value of work function corresponds to more considerable electronegativity of the chemisorption atom.

The current article presents the results of a study of the effect of single-walled carbon nanotubes carcass defects on their electronic structures and optical properties. The study was carried out using an ab-initio quantum mechanical approach: the pseudo-potential method in the density functional theory (DFT) framework in the local density approximation. It is shown that the defects of a single or double vacancy, and Stone- Wales change the absorption spectrum of nanotubes. This can be expressed in the appearance of absorption in the low-energy region and in the smearing of the absorption peaks corresponding to electron transitions between Van Hove singularities near the Fermi energy.

It is shown that the non-uniform elastic strain is the memristive switching origin in carbon nanotubes (CNT). The dependence of the resistance ratio in high- and low-resistance states of the non-uniformly strained CNT on the value strain is obtained. The process of the strain redistribution and its effect on the conductivity of CNT under action of the external electric field strength is studied. The obtained results can be used to develop memristor structures with reproducible parameters based on non-uniformly strained of carbon nanotubes.

This paper considers the fabrication of a superminiaturized sensor based on carboxyl-modified carbon nanotubes. The possibility of using nanotubes modified by carboxyl group for detection of alkaline metals is analyzed. Simulation results have been reported for the binding process of carboxyl group to the nanotube surface and interaction of the nanosystem fabricated with atoms of potassium, sodium and lithium. The simulation has been carried out using the molecular cluster model and the MNDO and DFT calculation methods. Sensor properties of surface and boundary carboxyl-modified nanotubes for alkaline metals have been compared. It has been proved that surface carboxyl-modified nanotubes are characterized by higher sensitivity for the selected atoms.

The specific surface area of multi-walled carbon nanotubes (MWCNT) of different geometry and structures is measured by the method BET. The nanotubes were synthesized by the use of highly effective Fe–Co catalysts through the method of polymerized complex precursors. In some cases, the measured specific surface area considerably exceeds that calculated under the assumption that the Ar adsorption occurs on the outer surface of CNTs. This permits one to conclude that in some cases a part of argon adsorbed fills the internal hollow of nanotubes.

Using the dielectrophoresis method with unipolar rectangular pulses for the deposition of carbon nanotubes (CNTs), functionalized by COOH groups, single nanosized contacts based on a single-walled CNT and a functionalized single-walled CNT have been formed, the specific contact resistance of which, according to the estimate, was about 0.25 µΩ·cm2 or about 6 MΩ per one cross-junction of CNTs. The possible usage of the proposed technique for the nanoscale contacts formation based on the cross-junction of CNTs in various layers for the study of organic materials and charge transport in a nanoscale channel is considered.

We studied the influence of the synthesis temperature on geometric parameters and structural perfection for vertically aligned carbon nanotubes (VACNT). We established that a synthetic temperature of 750 ◦C allows one to obtain the lowest concentration of defects in VACNT, with a diameter of 44±3 nm and a height of 80±9 nm. When temperature is increased up to 800 ◦C, an increase of the VACNT geometric dimensions was observed, which may be due to an increase in the catalytic centers (CCs) migration rate and their integration into larger centers. Also, at 800 ◦C, the concentration of defects in the nanotubes was increased due to the violation of carbon bonds during the acceleration of the acetylene desorption process from the surface of the sample.

The structural, chemical, and electronic characteristics of graphene grown by thermal decomposition of a singlecrystal SiC substrate in Ar atmosphere are presented. It is shown that this technology allows the creation of high-quality monolayer graphene films with a small fraction of bilayer graphene inclusions. The performance of graphene on SiC as a gas sensor or a biosensor was tested. The sensitivity of gas sensors to NO2 on the order of 1 ppb and that of biosensors to fluorescein with concentration on the order of 1 ng/mL and to bovine serum albumin–fluorescein conjugate with concentration on the order of 1 ng/mL were determined.

Graphene oxide produced by the standard Hammers method was annealed at various temperatures. The measurements indicate a monotone enhancement of the electric conductivity of the annealed graphene oxide samples with the increase of the annealing temperature. The most prominent jump in the conductivity (about five orders of magnitude) occurs between 150 and 180 ◦C. At the annealing temperature of 800 ◦C, the conductivity of reduced graphene oxide reaches the values typical for highly oriented pyrolytic graphite. The measurements demonstrate a non-linear character of conduction of reduced graphene oxide (RGO) samples, which manifests itself in a sensitivity of the sample conductivity to the magnitude of the applied voltage. This phenomenon is explained in terms of the percolation conduction mechanism of the RGO samples, in accordance with which the charge transport is provided by a limited number of percolation paths formed by contacting RGO fragments. A model simulation performed on the basis of the percolation mechanism of RGO conduction agrees qualitatively with the experimental data obtained.

The changes occurring on the surface of graphene nanoplatelets (GNPs) during treatment with gaseous fluorine are shown. According to Raman and IR spectroscopy, C–F covalent bonds are formed. As the fluorination temperature increases, the destructive changes in the GNPs become more noticeable, as evidenced by the results of X-ray diffraction analysis and the specific surface area of the samples. The presence of fluorine-containing functional groups contributes to better dispersion of the GNPs in the epoxy matrix and to an increase in their strengthening effect. The epoxy composite containing 0.1 wt% of the GNPs treated with fluorine at 450 ◦C presents the maximum strength characteristics: in comparison with the unmodified material, the tensile stress increases by more than 2 times, the tensile modulus – by 20 %, the breaking stress at bending – by 80 %, and the modulus of elasticity at bending – by 60 %.

In the present study, we have conducted molecular modeling of a potential method of graphene sheet formation. As the nano-sized blocks from which graphene can be synthesized, pyrene and pyrene butyric acid are chosen. The potential of several compounds (namely, Pt, Pd, Ni, AlCl3 and PdCl4) as catalysts for hydrocarbon condensation has been estimated by semiempirical calculations. The heat of formation in the series Pt, Pd, Ni, PdCl4, AlCl3 for pyrene is reduced to a minimum and reaches a value of 99 kJ/mol, and for pyrene butyric acid in the series Pt, Ni, Pd, PdCl4, AlCl3 decreases to 295 kJ/mol. According to the results of calculations, Pt and Ni can be the most effective catalysts for this reaction. As a substrate (or 2D nanoscale), we propose to use a surface of water or a monolayer of surfactants on water (this method is realized by the Langmuir–Blodgett method) having a 2D crystal structure whose state can be controlled by external conditions.

The paper discusses a possible model of low-field electron emission that could be applicable to carbon island films on silicon. Such films were recently showed to have emission thresholds as low as 0.4–1.5 V/µm. Discontinuity of the film – and not the presence of field-enhancing morphological features or low-workfunction spots – seems to be the necessary condition for good emission capability. We suggest a hot-electron emission model with emission center representing a single isolated nanosized island of sp2 carbon having the properties of a quantum dot. Quantization of its electron energy spectrum determines electron/phonon decoupling (“phonon bottleneck” effect) and long electron relaxation times, which makes emission the dominating option for hot electrons of sufficient energy injected in the island. The consequences of this suggestion are quantitatively considered for typical experimental situation.

The present paper describes the adsorption of lead (II) ions on conventional and nanoporous materials. Equilibrium studies were performed by implementing the empirical Freundlich and Langmuir isotherm models. It was found that all the isotherms constructed on the basis of experimental results fitted well to those models, thereby indicating the efficiency of the nanoporous materials as adsorbents of heavy metals. The experimental lead (II) maximum adsorption capacity of the materials under study – CNTs “Taunit-M”, highly porous carbon, CNTs “Taunit”, BAU-An activated carbon, and bentonite clay – was found to be 23, 14, 13, 10, and 7 mg·g−1, respectively. Due to the high sorption characteristics and unique physical and chemical properties of these materials, the adsorption technologies developed herein may act as good sustainable options for heavy metal removal from industrial effluents.

The present paper contains comprehensive studies on the adsorption properties of graphene oxide (GO), coconut activated carbon (AC) and “Taunit-M” carbon nanotubes (CNTs). Cu(II) ions served as extracted component. Measurements of the Cu(II) content in water were performed using electrothermal atomization atomic absorption spectroscopy. The obtained experimental data indicate high adsorption capacity of the GO along with CNTs and AC. Kinetic parameters of the adsorption process on the graphene oxide were calculated using standard models (pseudo- first- and pseudo-second-order, external and intraparticle diffusion, and Elovich models). The presented results demonstrate the prospects of using the GO in selective extraction of heavy and rare-earth metal ions from aqueous media.

The structure and physical properties of superparamagnetic Fe@C nanoparticles (Fe@C NPs) as well as their uptake by living cells and behavior inside the cell were investigated. Magnetic capacity of Fe@C NPs was compared with Fe7C3@C NPs investigated in our previous work, and showed higher value of magnetic saturation, 75 emu.g−1 (75 Am2·kg−1), against 54 emu.g−1 (54 Am2·kg−1) for Fe7C3@C. The surface of Fe@C NPs was alkylcarboxylated and further aminated for covalent linking to the molecules of fluorochrome Alexa Fluor 647. Fluorescent Fe@C-C5ON2H10-Alexa Fluor 647 NPs (Fe@C-Alexa NPs) were incubated with HT1080 human fibrosarcoma cells and investigated using fluorescent, confocal laser scanning and transmission electron microscopy. No toxic effect on the cell physiology was observed. In a magnetic field, the NPs became aligned along the magnetic lines inside the cells.

Electrochemical double-layer capacitors (EDLC) are emerging energy storage technology, highly demanded for rapid transition processes in transport and stationary applications, concerned with rapid power fluctuations. Rough structure of activated carbon, widely used as electrode material because of its high specific area, leads to poor electrode conductivity. Therefore there is the need for conductive additive to decrease internal resistance and to achieve high specific power and high specific energy. Usually, carbon black is widely used as conductive additives. In this paper, electrodes with different conductive additives – two types of carbon black and single-walled carbon nanotubes – were prepared and characterized in organic electrolyte-based EDLC cells. Electrodes are based on original wood-derived activated carbon produced by potassium hydroxide high-temperature activation at Joint Institute for High Temperatures RAS. Electrodes were prepared from slurry by cold-rolling. For electrode characterization cyclic voltammetry, equivalent series resistance measurements and galvanostatic charge – discharge were used.

The method of self-propagating high-temperature synthesis has been employed to prepare 2D graphene structures (SHS-graphSHS procedure for carbonizing cyclic organic structures is a simple accessible method for making 2D graphene structures in practically needed amounts. The material obtained is designated as SHS-graphene. The study on starch carbonization product by combined complementary methods has shown the structure of SHS-graphene particles is similar to 2–3-layered graphene particles. The addition of graphene to NBR matrix results in the significant (to twice) enhancement of strength and thermal characteristics of composition material obtained, as compared to unfilled rubber.ene). A set of complementary methods (scanning electron microscopy, Raman microscopy, X-ray diffraction analysis) evidenced 2–3-layer graphene structure of the substance obtained. SHS-graphene has been utilized to modify NBR and thereby markedly strengthen the polymer matrix.

The research of nanoparticle ion sputtering is interesting both from the fundamental point of view – for researching the interior structure of nanoobjects. Additions to the simple model of ion sputtering which allow one to consider special properties of the ion sputtering of nanoparticles, fullerenes and carbon nanotubes are introduced in this project.

It is shown that Raman spectra of nanocrystals with complex geometric shape can acquire additional broadening. In order to describe complex geometric shapes of nanocrystals in terms of its influence on the Raman spectrum, a parameter was introduced for the shape – roughness parameter. The roughness is defined as a relative parameter of the presence of additional volume on the faces of the cubic nanocrystal. The calculations for additional broadening of the Raman spectral line were made for 3–10 nm nanodiamonds.