Russian Journal of Physical Chemistry B最新文献

The paper presents the study of two types of composite materials containing copper micro- and nanoparticles in a polyethylene matrix. Two types of copper-containing fillers were used to prepare the composites: microparticles with an average size of 3.5 μm; nanoparticles of an average size of 13 nm with a core-shell structure. The study of the temperature dependence of the electrical conductivity of copper microparticles at fixed pressures showed that the shell formed on their surface, consisting of copper oxide, exhibits a semiconducting character. Additionally, the conductivity and static permittivity of polyethylene infused with copper nano- and microparticles were examined near the percolation threshold. Discrepancies emerged between experimental findings and predictions of the modern inhomogeneous systems theory at conductivity levels below a certain threshold. In the composites with copper nanoparticles located below the percolation threshold, an additional influence on both electrical conductivity and permittivity was observed. The reasons for this effect are discussed here simultaneously taking into account the spatial structure of the hierarchical model for composite materials proposed by the scientific group of I. Balberg.

A thorough examination of the supramolecular interactions of the title complex [Mn(L)₂]·(CH₃OH)] [HL=2-((2-(4,6-dimethylpyrimidin-2-yl)hydrazono)methyl)phenol] is conducted. Our research highlights the significance of weak intermolecular interactions in stabilising crystal self-assembly. These interactions are controlled by strong hydrogen bonding interactions, specifically N–H⋯O, C–H⋯π and also π⋯π interactions. The electronic structure of the complex was simulated using Density Function Theory calculations. Theoretically calculated structural parameters are in good match with the experimentally obtained parameters from single crystal X-ray diffractometer. The complex’s molecular reactivity and stability were examined using frontier molecular orbital analysis as well as molecular electrostatic potential (MEP). Time-Dependent Density Functional Theory calculation is performed to simulate the UV-Vis absorption spectra of the complex. Further, Hirshfeld surface analysis which uses molecular surface contours and two-dimensional fingerprint plots to visually analyse intermolecular interactions in crystal structures, has been used to examine molecular morphologies. The Hirshfeld surface and fingerprint plots are accompanied by crystal structure analysis allowed for the discovery of the important intermolecular interactions. We further studied the interactions of complex with human serum albumin active site with the aid of molecular docking studies using Autodock vina and found that the complex interacts with the protein Human serum albumin and showed attractions towards polar residues.

This work continues the recently started study of radiation chemistry of boron difluoride β-diketonates with an eye to the use of the dyes of this family in ionizing radiation dosimetry. Using three compounds that are generally similar in structure but differ in one substituent, we prepared a series of thin poly(methyl methacrylate) (PMMA) films, whose optical response to X-rays was comprehensively examined and collated with the reaction of the same molecules in organic solvents. The demonstrated differences indicate the importance of a detailed investigation of the transition from liquid dosimetric solutions of organic dyes to their polymeric films.

In the present work, the structural, electronic, and optical properties of the ({text{N}}{{{text{a}}}_{2}}{text{S}}{{{text{O}}}_{4}}cdot10{{{text{H}}}_{2}}{text{O}}) compound have been studied. We carried out the plane-wave pseudo-potential approach within the framework of the first principles of density functional theory (DFT) implemented with the Cambridge serial total energy package (CASTEP) code. The electronic band structure reveals the metallic nature of the compound. The computed geometrically optimized structure of the unit cell parameters was found to be in good agreement with the experimental monoclinic crystal structure data of the compound. For the first time, we have investigated the optical properties of ({text{N}}{{{text{a}}}_{2}}{text{S}}{{{text{O}}}_{4}}cdot{{;}}10{{{text{H}}}_{2}}{text{O}}) since no other experimental or theoretical studies on the optical properties and dielectric functions of ({text{N}}{{{text{a}}}_{2}}{text{S}}{{{text{O}}}_{4}}cdot{{;}}10{{{text{H}}}_{2}}{text{O}}) have been reported yet. The reflectivity spectrum shows that the reflectivity is high in the visible-ultraviolet region up to (20{text{ eV}}), indicating promise as a good solar energy storage material.

Heteroclusters of (Si,Zn,Ag)-Doped GaInP/GaInAs can attract considerable attention for storage energy in solar cells. A comprehensive investigation on energy grabbing by GaInP, Si@GaInP, Zn@GaInP, Ag@GaInP, GaInAs, Si@GaInAs, Zn@GaInAs, Ag@GaInAs was carried out including using DFT computations at the CAM–B3LYP–D3/6-311+G(d, p) level of theory. Electromagnetic and thermodynamic properties of GaInP, Si@GaInP, Zn@GaInP, Ag@GaInP, GaInAs, Si@GaInAs, Zn@GaInAs, Ag@GaInAs heteroclusters have been evaluated. The hypothesis of the energy adsorption phenomenon was confirmed by density distributions of CDD, TDOS and ELF for GaInP, Si@GaInP, Zn@GaInP, Ag@GaInP, GaInAs, Si@GaInAs, Zn@GaInAs, Ag@GaInAs heteroclusters. In GaInP and GaInAs, the photo excited electrons and holes are strongly bounded by the excitons because of their large exciton binding energy as (E_{{{text{Ag@GaInX}}}}^{{text{o}}}) > (E_{{{text{Zn@GaInX}}}}^{{text{o}}}) > (E_{{{text{Si@GaInX}}}}^{{text{o}}}) (X = P or As) due to its efficient exciton dissociation. Therefore, it can be considered that zinc and silver atoms in the functionalized Zn@GaInP/As and Ag@GaInP/As might have more impressive sensitivity for accepting the electrons in the process of energy adsorption mechanism. The changes of Gibbs free energy versus dipole moment could detect the maximum efficiency of Ag@GaInP and Ag@GaInAs heteroclusters for energy storage in the solar cells through (Delta G_{{{text{f}},{text{Ag}}@{text{GaInP }}}}^{{text{o}}}) = –134.9792 × 10³ kcal/mol and (Delta G_{{{text{f}},{text{Ag}}@{text{GaInAs }}}}^{{text{o}}}) = –132.1931 × 10³ kcal/mol, respectively. As a matter of fact, it can be observed that doped heteroclusters of Ag@GaInX and Zn@GaInX (X = P or As) might ameliorate the capability of GaInX (X = P or As) in solar cells for energy storage.

The processes of water freezing and ice thawing were studied in hydrogels based on sodium polyacrylate, sodium alginate, carboxymethylcellulose of different degrees of crosslinking, and para-aramid hydrogels filled with water. Using magnetic resonance imaging (MRI) method the hydrogels swelling, water distribution within the para-aramid hydrogel, freeze/thaw front propagation and resulting changes in ice composites structure were visualized. It was observed that the presence of a polymer macromolecular network in ice composites based on cross-linked hydrogels hinders the size of ice crystallites formed during freezing, leaving the qualitative picture of the freezing processes unaffected. At the same time, the water-filled porous structure of the para-aramid hydrogels undergoes irreversible changes during the freezing process, which leads to the destruction of the ice composite. It was found out that the rate of freeze/thaw front propagation in ice composites based on cross-linked hydrogels depends on both the mass content of the polymer material and its crosslinking degree. The results obtained demonstrate the capabilities of MRI in studying the heat and mass transfer processes in ice composite materials, which have potential for practical application.

Porous anodic aluminum oxide (PAAO) due to its accessible manufacturing technology and unique physical and chemical properties has found wide application in various fields of science and technology. The PAAO is formed in sulfuric acid and consists of ordered arrays of pores with an average diameter in the range 10–15 nm. However, for samples synthesized at the electrolyte temperature of 40°C, the surface becomes disordered and consists of individual thread-like fibers. For the first time, paramagnetic centers (defects) were identified and their influence on PL of analyte (Rhodamine B) was studied in a series of samples obtained in a wide temperature range: 5–40°C. It was established that in PAAO formed at 5°C oxygen vacancies (F⁺ centers) are detected. In samples synthesized at higher temperatures Al–SO₄ paramagnetic complexes are additionally observed, the maximum concentration of which is achieved in samples obtained at an electrolyte temperature of 25°C and is more than an order of magnitude higher than the concentration of F⁺ centers. The minimum PL intensity of the Rhodamine B was found in samples with the highest concentration of paramagnetic centers. This effect is due to the fact that part of the exciting radiation is absorbed by paramagnetic centers (Al–SO₄ and F⁺), therefore the PL of the dye decreases. Therefore, it is possible to control the type, concentration of paramagnetic centers in PAAO and the intensity of photoluminescence of the dye in its pores by varying the temperature of the electrolyte and dye concentration. The obtained results may be useful in the development of PAAO-based optical sensor platforms.

This article used one simple heat treatment to prepare high efficient Sn₂₁Cl₁₆(OH)₁₄O₆/SnO₂ composite photocatalysts using anhydrous SnCl₂ and NaOH powders as raw materials. The structural characteristics of the synthesized catalysts were studied using analysis techniques such as powder XRD, SEM and DRS. The research results showed that Sn₂₁Cl₁₆(OH)₁₄O₆/SnO₂ composites were prepared by heat treatment. An increase in the content of NaOH in the raw material can promote the transformation of Sn₂₁C-l₁₆(OH)₁₄O₆ into SnO₂. As the content of NaOH increased, the corresponding content of SnO₂ in the product also increased. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images reveal that the sample was composed of aggregates formed by the focusing of a large number of nanocrystals. DRS analysis shows that compared to SnO₂ reagent and single-phase Sn₂₁Cl₁₆(OH)₁₄O₆, the synthesized sample had much stronger absorption ability in the visible light region, and the bandgap value of the samples were obviously reduced. The photocatalytic experiment proves that the prepared catalysts exhibits excellent photocatalytic degradation ability. Under simulated sunlight and visible light irradiation, samples with lower NaOH content in the raw material can completely degrade methyl orange in 6 minutes and 15 min, respectively. Finally, a reaction mechanism for photocatalytic degradation of methyl orange was proposed.

This article adopts a simple solid-phase reaction method to rapidly synthesis efficient SnO/Sn composite photocatalysts using SnCl₂·2H₂O and NaOH powders as raw materials. The structural characteristics of the synthesized catalysts were systematically studied using analysis techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. The research results show that SnCl₂·2H₂O and NaOH can quickly react and generate SnO/Sn composites by being placed in a centrifuge tube and shaken by a vortex mixer. NaOH has a strong reducing ability towards divalent tin, and as the content of NaOH increased, the proportion of Sn in the corresponding products significantly increased. Scanning electron microscopy and transmission electron microscopy images reveal that the sample was composed of aggregates formed by the focusing of a large number of nanocrystals. The X-ray photoelectron spectroscopy characterization confirmed the presence of oxygen vacancy defects in the sample. The diffuse reflectance spectroscopy analysis shows that compared to SnO reagents, the synthesized samples had strong absorption ability in both ultraviolet and visible light regions. The photocatalytic experiment proved that the prepared catalysts exhibit excellent photocatalytic degradation ability. Under simulated sunlight irradiation, the sample with lower NaOH in the raw material can completely degrade methyl orange within 9 min. Finally, a reaction mechanism for photocatalytic degradation of methyl orange was proposed.

Fluorine-doped tin dioxide (SnO₂:F) films were deposited onto glass substrates using a facile spray pyrolysis method. The effect of solution concentrations on the structural, morphological and optical properties of SnO₂:F films is investigated using various characterization studies. All films exhibited tetragonal rutile structures with a preferred orientation in the (110) plane, which changes to the (211) plane gradually with increasing solution concentration. The average crystallite size of SnO₂:F films decreased as the solution concentration increased, ranging from 40.29 to 38.05 nm. Atomic Force Microscopy (AFM) analyses revealed a marked improvement in grain distribution with increasing solution concentration, accompanied by a corresponding enhancement in surface pressure and decreased roughness. All the regions, produced samples exhibited high transparency from 70 to 82%. The SnO₂:F (0.4 mol/L) film has the best transparency (≈82%). The band gap values of SnO₂:F films with different solution concentrations (0.2, 0.3, and 0.4 mol/L) are 3.84, 3.93 and 3.97 eV respectively, with a high band gap of 3.97 eV for the SnO₂:F (0.4 mol/L) films. Hot probe studies reveal that all films exhibit n-type conductivity. The lowest resistivity of 8.4 × 10^–4 Ohm cm was found for films deposited at 0.4 mol/L. The figure of merit (({{phi }_{{{text{TC}}}}})) of SnO₂:F thin films revealed a maximum value of about 9.757 × 10^–3 Ohm^–1 at the wavelength of 500 nm. These results suggest that SnO₂:F films fabricated by spray pyrolysis can be considered effective candidates for integration into optoelectronic devices, particularly as transparent conductive layers in photovoltaic applications.