Dmitry I. Petukhov

Study of the electronic structure of single-walled carbon nanotubes filled with cobalt bromide

Single-walled carbon nanotubes have been filled with cobalt bromide. The microstructure, optical properties, and effect of the introduced CoBr2 compound on the electronic structure of the nanotubes have been studied. It has been shown that the electron density in the resulting nanocomposites is transferred from the walls of the nanotubes to the nanocrystals of cobalt bromide, which is an electron acceptor.

Electric-Field-Assisted Self-Assembly of Colloidal Particles

A method for formation of photonic crystals has been proposed. The method is based on convective deposition of colloidal particles onto vertical substrates in the presence of a direct-current electric field directed perpendicular to the surface of the formed film and an alternating-current electric field applied parallel to the substrate plane. The structure and optical properties of the prepared colloidal crystals have been investigated using scanning electron microscopy, high resolution small-angle X-ray diffraction, and optical spectroscopy.

Morphological modification of the surface of polymers by the replication of the structure of anodic aluminum oxide

Anodic aluminum oxide films have been used as stamps to modify polymer materials in order to create superhydrophobic surfaces. Using polyethylene terephthalate, it has been shown that a high replication degree leads to a strong increase in the water wetting contact angle (up to 174°). However, the inverse situation is observed for the case of low replication degrees: hydrophilization of the surface occurs, which can be explained by a change of the Cassie-Baxter wetting mechanism to the Wenzel mechanism.

Confinement effects of CdSe nanocrystals intercalated into mesoporous silica

CdSe nanocrystals are intercalated into ordered hexagonal arrays of mesoporous silica. The nanocrystals are clearly confined in the channels and their size was estimated to be consistent with the pore size. Transmission electron microscopy suggests that CdSe nanocrystals have a spherical morphology and are stabilized from aggregation after intercalation. The shift of the longitudinal optical bands in the Raman spectra is caused by a combination of phonon confinement and strain effects from the compressed lattice of the intercalated CdSe nanocrystals and the experimental results agree well to the theoretical consideration.

Immobilization of nanostructured metal silver at the surface of anodic titanium dioxide for the creation of composites with the surface plasmon resonance

X-ray-amorphous anodic titanium dioxide is proposed as a carrier of nanostructured silver with a controllable surface roughness for the creation of composite films with an effect of the surface plasmon resonance in the visible region for the spectroscopy of giant combinational scattering (GCS). A comparative analysis of GCS composites obtained by different methods of silver immobilization at the surface of a semiconductor TiO2 (photolysis of silver nitrate (I), magnetron sputtering, and thermal decomposition of ammonium silver complex (I)) has shown a substantial dependence of the functional characteristics on preparation history in the case of model analytes with different spectral characteristics, i.e., dyes of rhodamine 6G and methylene blue in low concentrations of 1 × 10−8 mol/L by an aliquot volume of less than 10 μL.

Effect of nanostructured carbon coatings on the electrochemical performance of Li1.4Ni0.5Mn0.5O2+x-based cathode materials

Nanocomposites of Li1.4Ni0.5Mn0.5O2+ x and amorphous carbon were obtained by the pyrolysis of linear and cross-linked poly(vinyl alcohol) (PVA) in presence of Li1.4Ni0.5Mn0.5O2+ x. In the case of linear PVA, the formation of nanostructured carbon coatings on Li1.4Ni0.5Mn0.5O2+ x particles is observed, while for cross-linked PVA islands of mesoporous carbon are located on the boundaries of Li1.4Ni0.5Mn0.5O2+ x particles. The presence of the carbon framework leads to a decrease of the polarization upon cycling and of the charge transfer resistance and to an increase in the apparent Li+ diffusion coefficient from 10−16 cm2·s−1 (pure Li1.4Ni0.5Mn0.5O2+ x) to 10−13 cm2·s−1. The nanosized carbon coatings also reduce the deep electrochemical degradation of Li1.4Ni0.5Mn0.5O2+ x during electrochemical cycling. The nanocomposite obtained by the pyrolysis of linear PVA demonstrates higher values of the apparent lithium diffusion coefficient, a higher specific capacity and lower values of charge transfer resistance, which can be related to the more uniform carbon coatings and to the significant content of sp2-hybridized carbon detected by XPS and by Raman spectroscopy.

The thermal stability of porous anodic titania films

Porous titania films consisting of ordered aligned nanotubes have been synthesized by the method of two-stage anodic oxidation of metallic titanium at 60 V in 0.25% NH4F. The porous structure of the films has been studied by scanning electron microscopy (SEM); the thermal stability of anodic films has been investigated by SEM, XDR, thermal analysis, and IR spectroscopy. According to XRD it was established that the anodic titania film is amorphous and the amorphous titania starts to crystallize into the anatase phase under the temperature range of 300–310 °C. In addition, the coherence scattering region has been calculated from XRD data. The assumption that the porous structure does not destroy while the size of crystallites is less than the thickness of the pore wall has been confirmed by SEM data.

The effect of geometric confinement on gas separation characteristics of additive poly[3-(trimethylsilyl)tricyclononene-7]

E. A. Chernova, M. A. Bermeshev, D. I. Petukhov, O. V. Boytsova, A. V. Lukashin, A. A. Eliseev Lomonosov Moscow State University, Leninskiye Gory, Moscow, 119991, Russia A. V. Topchiev Institute of Petrochemical Synthesis (TIPS) Russian Academy of Sciences, Leninsky prospect, 29, Moscow, 119991, Russia Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky prospect, 31, Moscow, 119991, Russia