Russian Journal of Physical Chemistry A最新文献

This study investigates the removal of malachite green (MG) dye from aqueous solutions using the strong acid cation-exchange resin, Purolite C100. Batch adsorption experiments were conducted to evaluate the influence of key operational parameters, including initial pH, resin dosage, initial dye concentration, and temperature. Kinetic analysis revealed that the pseudo-second-order (PSO) model provided an excellent fit to the experimental data (R² > 0.99), suggesting that the rate-limiting step involves chemisorption-type interactions. Equilibrium data were best described by the Redlich–Peterson isotherm model, indicating a hybrid adsorption mechanism. The Langmuir model also provided a good fit, yielding a high maximum monolayer sorption capacity (qₘ) of 277.80 ± 9.63 mg g^–1 at 50°C. Thermodynamic analysis revealed that the process is thermodynamically favorable under standard conditions (∆G° < 0), endothermic (ΔH° = +7.7 ± 0.1 kJ mol^–1), and characterized by an increase in system entropy (ΔS° = +84.0 ± 1.1 J mol^–1 K^–1). Overall, this study confirms that Purolite C100 is a highly efficient and promising material for the sequestration of malachite green from contaminated wastewater.

In this work, we prepared perovskite by the addition of KI and investigated its effect on the efficiency of perovskite solar cells with carbon electrodes. We found that the addition of appropriate amounts of KI to perovskite precursor solution led to the increase in the crystalline size and crystallinity of perovskite and improved the light absorption of the prepared films. When the concentration of KI additive was 0.075 mol/L, the perovskite solar cell efficiency was 14.21%, which was 1.2-fold higher than that of the control (11.78%). The analysis showed that the addition of KI improved the characteristics of the device due to the improved crystallinity and crystallinity of perovskite and effective suppression of non-radiative recombination.

All calculations in hand have been investigated by using the first-principles method within the full-potential linearized augmented plane wave (FP-LAPW) method implemented in wien2k package. The framework of generalized gradient approximation (GGA96) has been used to describe the exchange-correlation potential. It has been found that the substitution and the increase of pressure cause a decrease in the bond length, lattice constant, and volume. Noticeably, the energetic properties are improved after applied pressure variations and the substitution, such as after the substitution of La with Y and Sc the heat of formation value reduces by about 20 and 10%, respectively. Otherwise, the gravimetric hydrogen storage (wt %) is increased after the substitution. Furthermore, the pressure variations and the substitution led to the Fermi energy value increased and the density of states at the Fermi level decreased.

A system with three or more components (n ( geqslant ) 3) is quasi-simple if the isotherms–isobars–isopotentials of the system’s components (the solvents of solubility diagrams) are line segments (n = 3), sectors of planes (n = 4), or hyperplanes (n ( geqslant ) 5). This work presents evidence that all figurative points on monovariant branches of the joint crystallization of two identical solid phases in different quasi-simple quaternary systems (n = 4) (with two identical and one different component) belong to a single curve. Systems of equations are given for thermodynamic calculations of such curves exclusively from data on binary subsystems. Examples of calculating these monovariant curves are provided, and agreement is shown between non-model calculations and experimental data on the compositions of saturated solutions using quaternary systems with a common cation, a common anion, and quaternary reciprocal systems as examples. Agreement is also seen between results from thermodynamic calculations and numerous experimental data. The results can naturally be extended to monovariant crystallization lines of three or more identical solid phases on the solubility diagrams of quasi-simple systems with five or more components (and one that is different).

The LiNi_1/3Co_1/3Mn_1/3O₂ cathode material was successfully synthesized by the co-precipitation-assisted polymer network gel method. The prepared LiNi_1/3Co_1/3Mn_1/3O₂ material had a relatively small particle size and exhibited excellent electrochemical performance. The sample can provide an initial discharge specific capacity of 196.0 mA h g^–1 (0.2 C). At a 2 C rate, the initial discharge reached 160.2 mA h g^–1, and the capacity retention rate was 62.7% after 100 cycles. In addition, at a high magnification of 5 C, the capacity retention rate still remained at 56.0%, after 100 cycles. Electrochemical data indicated that the LiNi_1/3Co_1/3Mn_1/3O₂ material exhibits superior rate performance. The excellent electrochemical performance of the material was attributed to the constraints of the gel grid and the generation of flowing gas during the calcination of the carbonate precursor, which hinder the agglomeration of the powder and further enhances the dispersibility of the particles. The obtained LiNi_1/3Co_1/3Mn_1/3O₂ cathode material with uniform particle size reduced the charge transfer resistance and enhanced the lithium ion diffusion capacity.

DFT modeling of lithium adsorption and intercalation processes was carried out for various configurations of graphene-like structures containing defects such as single vacancies and nitrogen doping. It was found that vacancies reduce the adsorption energy by forming stable binding centers. In nitrogen-doped systems, the adsorption energy remains stable with increasing lithium concentration. Intercalated structures exhibit a decrease in stability with an increasing number of lithium atoms, especially in the case of nitrogen doping, which is accompanied by deformation of the graphene layers.

The binary and more complex metallic melts are characterized by instability of composition along the height of the melt. After having been kept for a short time in a vertical nonwetted vessel (crucible or capillary), the initially homogeneous melt acquires a gradient of component concentrations along the height, and the heavy component is distributed along the height of the crucible according to the barometric distribution of large particles (clusters). This is one of the factors responsible for the cluster structure of melts. An analysis of the experimental results leads to the conclusion that there is a second mechanism of mass transfer in liquid metals, namely, the transfer of atoms in the interphase monatomic layer at the boundary between the melt and capillary wall, which occurs simultaneously with diffusion. A number of special experiments clearly confirm this hypothesis. The experiment showed that the choice of orientation for the distribution channel of the melt components relative to the direction of the gravitational field makes it possible to isolate both mechanisms practically in “pure form,” and there is evidently no other way to explain the results of the experiment.

An approach is proposed that can allow ab initio solution of the phase problem in X-ray diffraction studies. A synthetic diffraction data generator has been created that can be used to solve applied problems using machine learning. An automated container is presented that allows reproducible experiments aimed at solving the problem within the framework of the proposed approach. The FFT_UNet and XRD_Transformer models were developed, taking into account the physical specifics of the problem, and a comparative analysis and interpretation of their work on real data were carried out.

It is shown that the group and individual composition of A-92 motor gasoline can be determined on a PTMSP025 capillary column with a poly(1-trimethylsilyl-1-propyne) (PTMSP) stationary phase. It was found that the PTMSP column is characterized by the order of elution similar to that for capillary columns with porous organic polymers. Hydrocarbons are eluted in groups according to the number of carbon atoms in the molecule. Alkenes are eluted first in the group, and then alkanes are eluted. This order of hydrocarbon retention on the PTMSP025 column allows a more structured pattern of separation compared to the column with the polysiloxane stationary phase. Methyl-tert-butyl ether (MTBE), used as an octane booster, is determined on a PTMSP025 column without an additional sample preparation (concentration) step. The possibility of separating gasoline components using comprehensive two-dimensional chromatography was also demonstrated, where a PTMSP025 column was installed in the first dimension, and a column with dimethylpolysiloxane as a stationary phase in the second.

A systematic density functional theory (DFT) study has been performed to assess structures, stabilities and electronic properties of small Ni_xMo_y (x + y ≤ 6) clusters. The lowest energy structures have been determined by testing several possible geometries at the PBEPBE/SDD level of theory. The results suggest that the tetramer, pentamer and hexamer clusters prefer three-dimensional (3D) configurations. The dimers and pure Mo clusters are found to be more stable as compared to other clusters. Also, the NiMo dimer possesses the highest chemical reactivity among the examined clusters. The calculated vertical ionization potential (VIP) and vertical electron affinities (VEA) values of the clusters show their tendency towards accepting electrons. The natural bond orbital (NBO) analysis suggests that a charge transfer takes place from Mo atoms to Ni atoms within the NiMo and Ni₂Mo clusters, and vice versa in the Ni₃Mo, Ni₄Mo, and Ni₅Mo clusters. The H₂ adsorption on the Ni_x (x = 2–6) and Ni_xMo (x = 1–5) clusters has also been investigated. The results suggest that the hydrogen dissociation form is more favorable as compared to the molecular adsorption. Hydrogen atom tends to draw electrons from the metal cluster in the dissociative form of the Ni_xH₂ systems, while donate electron to the metal cluster in the molecular adsorption form. In the Ni_xMoH₂ clusters, electron donation occurs from the metal cluster to the hydrogen atom. The transition pathway from the H₂ molecular to dissociative adsorption on the NiMo and Ni₂ clusters has also been evaluated.