Russian Journal of Physical Chemistry A最新文献

Atmospheric aerosol deposition on the underlying surface in a forest area and over meadow vegetation on the southeastern coast of Lake Baikal have been studied. Based on the measurements of the height profiles of the number concentration of fine aerosol, it is shown that the aerosol concentration gradients over meadow vegetation are significantly higher than under the tree crown in the forest area and differ significantly. The concentration gradients of fine aerosol (FA) and submicron aerosol (SMA) particles under the tree crown in the forest vary within narrow ranges compared to those in the open country (meadow) and can be negative or positive (dC/dh). In experiments over meadow vegetation, the maximum concentration gradient was 180 (particles/cm³)/m for fine particles in the daytime and 4 (particles/cm³)/m for submicron aerosol in the morning. In the forest, the maximum is 110 (particles/cm³)/m for FA in the daytime and 1 (particle/cm³)/m for SMA particles. The low values of gradient under the tree canopy indicate that the tree crown has a significant effect on the deposition of aerosol particles in forest vegetation.

The laser heating of a cell of a representative volume of thermoplastic tape is modeled, and the procedure for generating filaments within the cell is revised. The bi-parametric problem of finding the optimum process for automated layup and winding is solved, and samples are manufactured to determine the specific energy of delamination at the limiting process parameters of a robotic layup system.

Polymer ligands based on apple pectin modified with amino acids (L-arginine, L-alanine, and L‑aspartic acid) were synthesized and characterized by IR and ¹³C NMR spectroscopy, polarimetry, viscometry, and elemental analysis. Based on the synthesized polymer ligands, new metal-polymer complexes of copper(II) were synthesized:. The stoichiometry of the resulting metal complexes and the pH ranges of their existence were determined using the spectrophotometric method and elemental analysis data. It has been established that the modification of pectin with amino acids increases the stability of copper-containing polymer complexes compared to their homoligand analogs in a medium simulating gastric juice.

The electrocatalytic properties of materials synthesized on multi-walled carbon nanotubes (MWCNTs) and pyrolyzate of the metalorganic framework Pyr_MIL-53(Al) in the oxygen reduction in an alkaline medium were compared. The catalysts were obtained by doping the supports with iron and cobalt phthalocyanines and modifying them with palladium. According to the IUPAC classification, the materials are type IV adsorbents, having a hysteresis of the H3 type, which indicates the presence of slit-like pores. When the MWCNTs are doped, the ordering of the catalyst surface significantly decreases, probably due to the formation of amorphous carbon during the decomposition of phthalocyanines. When Pyr_MIL-53(Al) is doped, the surface ordering increases, which is probably associated with graphitization of the carbon of the initial Pyr_MIL-53(Al) during the joint pyrolysis with phthalocyanines. The phase composition of the obtained catalysts was studied by XRD: the metals are present in the form of alloys and oxides. In the linear voltammetry mode, the MWCNT_CoPc_FePc_Pd catalyst showed activity in the oxygen reduction reaction (ORR) comparable to that of the commercial platinum electrode; the number of electrons participating in the reaction was more than 3.8. The MWCNT_CoPc_FePc_Pd catalyst exhibited a large electrochemically active surface area and high corrosion resistance associated with the self-activation effect. The trials of the MWCNT_CoPc_FePc_Pd catalyst under membrane electrode unit (MEU) conditions showed high efficiency of the material as an oxygen reduction catalyst for alkaline fuel cells.

Reduced graphene oxide (rGO) has proven to be a transformative material in dye-sensitized solar cells (DSSCs) due to its superior electrical conductivity and structural advantages. In this study, an rGO/TiO₂ bilayer photoanode was developed to enhance charge transport and suppress recombination. The rGO layer, deposited on an indium tin oxide (ITO)-coated substrate, acts as an interfacial material, significantly improving photocurrent generation by providing efficient electron transport channels. The TiO₂ layer, deposited over the rGO, offers a high surface area for dye adsorption and ensures optimal light harvesting. Electrochemical impedance spectroscopy confirmed that the rGO layer enhances charge transfer while minimizing recombination losses at the TiO₂ interface. This improvement is attributed to rGO’s high electrical conductivity and its ability to create a favorable energy barrier, facilitating efficient charge movement through the photoanode. Additionally, the incorporation of a chitosan-based polymer electrolyte with multi-walled carbon nanotubes (MWCNTs) as filler provided enhanced ionic conductivity and mechanical stability. A natural cocktail dye derived from moss and mulberry was employed as the sensitizer for its broad-spectrum absorption and eco-friendly nature, while a platinum counter electrode ensured efficient redox reactions. This integration of materials highlights the potential of rGO/TiO₂ bilayers in achieving high photovoltaic performance, offering a sustainable and cost-effective pathway for advancing DSSC technology.

The results of the kinetics study of the isotope exchange reaction between water and chloroform, one of the methods for obtaining deuterochloroform, used as a solvent for nuclear magnetic resonance spectroscopy, are presented. It is shown that increasing the temperature from 298 to 323 K leads to an increase in the observed rate constant by almost an order of magnitude. The results of the study of the reaction kinetics depending on the concentration of the catalyst, alkali, are presented. Thus, increasing the concentration of alkali from 0.05 to 0.1 M leads to a 4-fold acceleration of the reaction. It is shown that the reaction rate does not depend on the alkali cation. The paper also presents the definitions of the separation coefficient of the studied system in the temperature range of 298–323 K: the heavy isotope, deuterium, is concentrated in the organic phase, and the value of the single separation effect decreases from 1.062 ± 0.015 to 1.034 ± 0.011.

Photocatalytic technology, renowned for its green, economical, and highly efficient characteristics, has garnered significant attention in the fields of wastewater treatment and environmental remediation. In this study, Ba_0.7Sr_0.3TiO₃ was synthesized via the solid-state method, and g-C₃N₄ was incorporated to construct a g-C₃N₄/Ba_0.7Sr_0.3TiO₃ multiphase composite with enhanced photocatalytic performance. The photocatalytic efficiency of the composite catalysts with varying mass fractions was evaluated for the degradation of tetracycline hydrochloride. The g-C₃N₄/Ba_0.7Sr_0.3TiO₃ composite was characterized using XRD, SEM, UV–Vis, and PL techniques to analyze its crystal structure, microstructure, and optical properties. The results demonstrated that the composite with 5% g-C₃N₄ mass fraction exhibited the highest photocatalytic activity, achieving a tetracycline hydrochloride degradation rate of 86% within 120 min, compared to 67% for pure Ba_0.7Sr_0.3TiO₃. These findings indicate that the incorporation of g-C₃N₄ effectively reduces the band gap of the composite, increases carrier concentration, and significantly enhances photocatalytic performance. This study highlights the potential of g-C₃N₄/Ba_0.7Sr_0.3TiO₃ as a promising material for photocatalytic applications in environmental remediation.

The structural, electronic and nonlinear optical (NLO) properties of BN-substituted graphdiyne (BNGDY) with the doping of Li₃NM (M = Li, Na, and K) alkalides are systematically studied using density-functional theory calculations, in order to disclose the effect of the alkalides on molecular optical properties. The results show that the Li₃NM alkalides can stably adsorb on the surface of six planar BNGDY structures, of which the structures with small substitution ratios of BN-pairs on diacetylenic linkages exhibit strong chemical stabilities. Moreover, the Li₃NM alkalides have the slightly increased charge transfer with alkali metals from Li to K, and that is a decreasing trend with increasing BN substitution ratios (A → F) on GDY. More interestingly, the successive introduction of the alkalides on BN-substituted graphdiyne can effectively modulate the electronic properties and nonlinear optical responses of the systems. Importantly, the BNGDY structure (D) with the doping of Li₃NLi on triangular hole possesses the excellent nonlinear optical performance with much larger first hyperpolarizability values (e.g., 1.890 × 10⁶ a.u.), which can be further understood by the analysis of the first hyperpolarizability density and the two-level model from the excitation energy calculations. This study will inevitably provide an excellent strategy for designing the next generation high-performance NLO materials.

The influence of the pore size of a nanoporous material and the rate of change in the internal volume of the nanoporous material–nonwetting liquid system on the filling pressure of the nonwetting liquid (distilled water) of hydrophobized nanoporous materials with pore sizes of 9 nm (Fluka 100 C8), 5 nm (Fluka 60 C8 PF), and 2 nm (MCM-41-C1) at rates of change in the volume of the nanoporous material–nonwetting liquid system of 2.7 × 10^–4, 2.7 ×10^–3, and 2.7×10^–2 cm³/s was studied. It was shown that decreasing the pore size increases the characteristic pore filling pressures, which follows from the classical theory of capillarity. It was also found that increasing the rate of change in the internal volume of the nanoporous material–nonwetting liquid system leads to an increase in filling pressures for all systems with an increase in the rate from 2.7 × 10^–4 up to 2.7 × 10^–3 cm³/s, but further increase in rate to 2.7 × 10^–2 cm³/s leads to an increase in filling pressures only for MCM-41-C1, while for other systems this increase is within the measurement error. Based on the results obtained, it can be concluded that there is a transition from a quasi-static to a quasi-dynamic filling mode. It is also possible to assume the existence of a critical pore size that determines condition for the growth of filling pressure with an increase in the rate of change in the internal volume of the system.

The process of reprocessed uranium enrichment according to a double-cascade scheme using an inert carrier gas to purify the regenerate from the isotope ²³²U is considered. Using the quasi-ideal cascade model, numerical studies of the influence of various process parameters on the distribution of key isotopes and the integral characteristics of the system were carried out. The limits of the possible purification effect, determined by the proportion of carrier gas in the feed of the second cascade while maintaining external enrichment conditions, are estimated. It is shown that an increase in the proportion of carrier gas in the second cascade feed leads to an increase in the isotope ²³⁶U content in the final product, which entails a significant (more than 1%) increase in ²³⁵U enrichment. In addition, the efficiency of the cascade scheme in terms of purification from ²³²U is largely determined by the choice of the operating mode of individual separation devices.