Russian Journal of Inorganic Chemistry最新文献

Catalysts for an environmentally friendly method for hydrogen production (free from carbon oxide emissions) based on decomposition of methane were proposed. The catalysts represented iron-containing systems supported on a carbon material (biochar). The active component (Fe) was deposited by the incipient wetness impregnation method from a solution of iron(III) nitrate nonahydrate. The produced catalytic systems were tested in the decomposition of methane and studied by physicochemical methods of analysis (Raman spectroscopy, powder X-ray diffraction, transmission electron microscopy, elemental analysis, and atomic absorption analysis). The catalysts were found to have a graphite-like carbon structure accommodating uniformly distributed iron nanoparticles. The catalytic activity of the obtained systems in the temperature range of 500–850°C was determined. The maximum conversion of methane (12.2%) was observed at 700°C in the presence of iron-containing biochar synthesized at 250°C. The carbon product formed during the experiment consisted of carbon nanotubes and onion-shaped carbon.

Solid solutions of Co_1–xCu_xCr₂S₄ (х = 0–0.6), spanning the compositional range between the ferrimagnet СоCr₂S₄ (T_C = 222 K) and the ferromagnet CuCr₂S₄ (T_C = 377 K), were synthesized via a solid-state reaction. Their magnetic properties were studied using a AC magnetic susceptibility measurement method in the temperature range of 2–300 K under an alternating magnetic field with an amplitude of 1 Oe at various frequencies (100, 1000, 5000, and 10 000 Hz). The substitution of Co by Cu from x = 0 to x = 0.6 was found to increase the magnetic ordering temperature from 222 K to 287 K. The nature of the magnetic phase transitions was determined, revealing a transition to a frustrated spin-glass state in the sample with x = 0.05.

A combined quantum-chemical and molecular dynamics study of atomic layer etching of amorphous zinc oxide by β-diketones—acetylacetone, 1,1,1-trifluoroacetylacetone, and 1,1,1,5,5,5-hexafluoroacetylacetone—was carried out using the ORCA 6.0.1 and LAMMPS software packages. Within the framework of density functional theory at the PBE-D3BJ/def2-SVP level, the energy parameters of adsorption and desorption were investigated, and the induced surface stress was quantitatively evaluated. It has been found that acetylacetone induces the highest surface stress (1.62 eV) and enables spontaneous etching due to its low desorption energy (2.10 eV). The fluorinated derivatives exhibit a self-limiting interaction behavior: 1,1,1-trifluoroacetylacetone, with a desorption energy of 3.27 eV, induces a surface stress of 1.05 eV, while 1,1,1,5,5,5-hexafluoroacetylacetone causes the weakest effect on the surface structure (1.01 eV) with a desorption energy of 2.53 eV. The results suggest that 1,1,1-trifluoroacetylacetone can be considered the most suitable precursor for controlled atomic layer etching of zinc oxide.

The interaction of bis(dioxane) and bis(tetrahydropyran) derivatives of iron(II) bis(dicarbollide) [8,8'-{O(CH₂CH₂)₂Х}₂-3,3'-Fe(1,2-C₂B₉H₁₀)₂] (Х = O, CH₂) with pyridine in an inert atmosphere has been studied. It has been found that the ring-opening of oxonium cycles proceeds stepwise, with the formation of the corresponding mono- and dipyridinium iron(II) complexes. Using the bis(dioxane) dipyridinium derivative as an example, it was found that, when in solution, oxidation of the resulting products to the corresponding paramagnetic complexes of iron(III) is possible. This approach opens the way to obtain bifunctional iron bis(dicarbolide) derivatives with different substituents. The obtained compounds have been characterized by multinuclear NMR and IR spectroscopies, as well as high-resolution mass spectrometry. The structure of the symmetrical dipyridinium iron(II) complex [8,8'-(C₅H₅NCH₂CH₂OCH₂CH₂O)₂-3,3'-Fe(1,2-C₂B₉H₁₀)₂] was determined by single crystal X-ray diffraction.

The effect of sonoplasma treatment on the generation of reactive oxygen and reactive chlorine species in waters of different salinity was studied. Chemiluminescent analysis and UV-visible spectrometry were employed to selectively detect and quantify the different types of reactive species. In distilled water, the sonoplasma treatment yielded 28.3 × 10^–4 M H₂O₂, but presence of NaCl caused a decrease in H₂O₂ yield. Sonoplasma treatment of the salt water yielded hypochlorite (ClO^–) as well, but its concentration did not exceed 1.2 × 10^–5 M and decreased with an increase in salinity. The degradation rate of model organic pollutants, methylene blue (MB) and methyl orange (MO) was analyzed in different sonoplasma treatment regimes. Kinetic analysis of the degradation revealed that, under plasma discharge, a direct decomposition of dyes occurs, while the contribution of reactive oxygen and reactive chlorine species generated during water plasmolysis is significantly lower. At the same time, the long-living H₂O₂ and ClO^– species are capable of decomposing the dyes even after the plasma treatment. The obtained results demonstrate the high efficiency of sonoplasma technology for the purification of both fresh and salt (up to 35 g/L NaCl) water and the importance of taking the salt concentration into account to optimize the purification process.

This study presents a simple and efficient method for synthesizing nanocrystalline zinc oxide using glycerate precursors. Zinc glycerates were obtained through thermal treatment of a solution of zinc acetylacetonate monohydrate in glycerol, followed by additional thermal processing, which resulted in the formation of nanocrystalline ZnO. The synthesized ZnO nanoparticles were characterized using XRD, SEM, and DTA/DSC techniques. The gas-sensing properties of ZnO toward a wide range of analyte gases were investigated. It was demonstrated that nanocrystalline ZnO exhibits high sensitivity and selectivity to NO₂. The proposed approach opens new prospects for the development of cost-effective and efficient gas sensors based on semiconductor oxides.

The influence of reaction parameters on the stabilization of nickel(II) ferrite hydrosols in the presence of polyethyleneimine (PEI) was studied by methods of mathematical planning and design of experiment (FFD 2^7-4). The nickel(II) ferrite hydrosol, which retained sedimentation stability for 2 months, was prepared under optimal conditions. The NiFe₂O₄/Au hybrid material was prepared by adsorption of gold seeds on the magnetic particles followed by four-step reduction of Au(III) with hydroxylamine in the presence of PEI. According to transmission electron microscopy and X-ray photoelectron spectroscopy data, the material consisted of uniform spherical Au⁰ nanoparticles of 4.0 ± 0.5 nm size uniformly distributed over the surface of ferrite nanoparticles of 9.7 ± 0.2 nm in diameter. Gold particles were strongly attached to the surface were not detached during post-synthetic and ultrasonic treatment. The content of gond particles can be adjusted by varying the number of gold reduction steps.

Silicophosphates A₂Zr₂SiO₄(PO₄)₂ (A = K, Rb, and Cs) with langbeinite structure have been synthesized and studied for the first time. The samples have been characterized by XRD, IR spectroscopy, scanning electron microscopy, and energy-dispersive X-ray microanalysis. Single phase silicophosphates have been prepared at 800°C. Refining of crystal structure of Rb₂Zr₂SiO₄(PO₄)₂ by Rietveld method have shown that the structure is based on 3D framework formed by ZrO₆ octahedra and (Si/P)O₄ tetrahedra, extra-framework alkali metal cations occupy separated cavities within the scaffold. Stretching and bending vibrations of SiO₄ and PO₄ tetrahedra have been determined for the compounds. Correlations between IR spectra and the nature of cation A⁺ have been revealed. Thermal stability of silicophosphates up to 1200°C has been confirmed by thermal X-ray diffraction and combined TG–DSC analysis. The linear thermal expansion coefficient of Cs₂Zr₂SiO₄(PO₄)₂ has been found to be α_a = 5.8 × 10^–6 K^–1. The obtained results allow one to conclude that the studied silicophosphate materials are highly persistent to extreme temperature conditions.

Amorphous and crystalline titanium-ammonium phosphates Ti₂O₂H(PO₄)[(NH₄)₂PO₄]₂ were synthesized by the hydrothermal method. It is shown that the minimum temperature and processing time for the crystallization of the Ti₂O₂H(PO₄)[(NH₄)₂PO₄]₂ phase are 160°C and 12 h, respectively. At the same time, NH⁴⁺ and ({text{PO}}_{4}^{{3 + }}~) ions are present in X-ray amorphous samples, similar to the crystalline compound, and during crystallization, a decrease in the content of water or hydroxyl groups and an increase in molar ratio of P : Ti are observed. X-ray amorphous samples consist of isotropic particles 10–15 nm in size, while crystalline samples contain diamond-shaped plates with smaller primary particles in their structure. X-ray amorphous and crystalline titanium-ammonium phosphates have low photocatalytic activity. The sun protection factor of X-ray amorphous samples, determined according to the international standard ISO 24443, is comparable to the sun protection factor of commercially available titanium dioxide.