Vladislav V. Shunaev

The propagation of a localized ring nonlinear wave in carbon nanotubes (CNTs) of armchair type has been explored using the MD/DFTB method. It is unambiguously shown that the considered localized waves are soliton-type. Herewith, the higher a velocity of an initial perturbation, the higher a steady-state velocity of the considered soliton. It is established that at a high initial excitation energy in a time period of 0.1–0.2 ps the soliton moves at the speed in the range of 245–270 Å/ps, which is approximately in 1.22–1.35 times higher than the speed of sound in CNTs (200 Å/ps). It is shown that the soliton velocity practically does not change with increasing CNT radius.

The combination of spinel Li₄Ti₅O₁₂ (LTO) with carbon nanostructures, such as graphene (G) and carbon nanotubes (CNTs), provides all of the required properties for modern chemical power sources such as Li-ion batteries (LIBs) and supercapacitors (SCs). G/LTO and CNT/LTO composites demonstrate a superior reversible capacity, cycling stability, and good rate performances. In this paper, an ab initio attempt to estimate the electronic and capacitive properties of such composites was made for the first time. It was found that the interaction between LTO particles and CNTs was higher than that with graphene due to the larger amount of transfer charge. Increasing the graphene concentration raised the Fermi level and enhanced the conductive properties of G/LTO composites. For CNT/LTO samples, the radius of CNT did not affect the Fermi level. For both G/LTO and CNT/LTO composites, an increase in the carbon ratio resulted in a similar reduction in quantum capacitance (QC). It was observed that during the charge cycle in the real experiment, the non-Faradaic process prevailed during the charge cycle, while the Faradaic process prevailed during the discharge cycle. The obtained results confirm and explain the experimental data and improve the understanding of the processes occurring in G/LTO and CNT/LTO composites for their usages in LIBs and SCs.

Nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) are widely used for drug delivery. One of the main challenges is to clarify their interaction with hypoxia-inducible factor 1 alpha (HIF-1α), the lack of which leads to oncological and cardiovascular diseases. In the presented study, N-MWCNTs were synthesized by catalytic chemical vapor deposition and irradiated with argon ions. Their chemical state, local structure, interfaces, Stone–Wales defects, and doping with nitrogen were analyzed by high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Using experimental data, supercells of functionalized N-MWCNTs with an oxygen content of 2.7, 4 and 6 at. % in carboxyl groups were built by quantum chemical methods. Our analysis by the self-consistent charge density functional tight-binding (SCC DFTB) method shows that a key role in the functionalization of CNTs with carboxyl groups belongs to Stone–Wales defects. The results of research in the decoration of CNTs with HIF-1α demonstrate the possibility of wave-diffusion drug delivery. The nature of hybridization and relaxation determines the mechanism of oxygen regulation with HIF-1α molecules, namely, by OH-(OH–C) and OH-(O=C) chemical bonds. The concentration dependence of drug release in the diffusion mode suggests that the best pattern for drug delivery is provided by the tube with a carboxylic oxygen content of 6 at. %.

Propagation of supersonic soliton in carbon nanotubes of armchair type

The propagation of a localized ring nonlinear wave in carbon nanotubes (CNTs) of armchair type has been explored using the MD/DFTB method. It is unambiguously shown that the considered localized waves are soliton-type. Herewith, the higher a velocity of an initial perturbation, the higher a steady-state velocity of the considered soliton. It is established that at a high initial excitation energy in a time period of 0.1-0.2 ps the soliton moves at the speed in the range of 245-270 Å/ps, which is approximately in 1.22-1.35 times higher than the speed of sound in CNTs (200 Å/ps). It is shown that the soliton velocity practically does not change with increasing CNT radius

Relying on empirical and quantum chemical methods, a hybrid nanocomposite based on the T-shaped carbon nanotube (CNT) junction and internal fullerene C₆₀ is proposed as a potential triple-value memory cell. The T-shaped CNT provides three potential wells where the internal fullerene can be located. The fullerene can move between these wells under the periodic external electric field, whose strength and frequency parameters are identified. The process of the fullerene’s motion control corresponds to the memory cell write operation. The read operation can be realized by determining the fullerene’s position inside the CNT by estimation of the charge transfer between a fullerene and the CNT’s walls. Calculations took into account such external factors as temperature and air environment.

The composites on the base of Co₃O₄ and graphene are in demand in the field of portable, flexible energy storage devices due to their small size, lightweight, big specific capacitance, good cycle stability and appropriate capacitance retention. The synthesis of this material always starts from the treatment of graphene oxide, so as a result, experimenters receive Co₃O₄ nanocubes incorporated into reduced graphene oxide indicates the presence of different oxygen-containing groups in the compound. This fact may limit the advantages of the considered material. Our theoretical quantum chemical calculations show that the process of Co₃O₄ incorporation between reduced graphene oxide layers is more energetically favorable in comparison to pure graphene. However, the win in the quantum capacitance in the case of pure graphene is in the range of 300–500 F/g in dependence on the applied voltage. The obtained result may indicate the need for modification of the current methods of graphene/Co₃O₄ synthesis to improve its application in supercapacitors and lithium-ion batteries.