Russian Journal of Inorganic Chemistry最新文献

Heterostructure Pt/ZnO nanocomposites were prepared by sonochemical-deposition method following the preparation of ZnO microflowers by simple precipitation method. Phase, morphology, oxidation state of element, specific surface area and optical properties of ZnO and heterostructure Pt/ZnO nanocomposites were characterized by X-ray powder diffraction, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET) surface area analysis, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectroscopy (DRS). The analytical results certified that face centered cubic metallic Pt⁰ nanoparticles were fully supported on the surface of nanopetals of hexagonal ZnO microflowers. In addition, the samples were studied for photodegradation of methylene blue (MB) and methyl orange (MO) under UV light irradiation. The heterostructure 0.5% Pt/ZnO nanocomposites have the highest MB and MO degradation because the Schottky barrier of metal–semiconductor interface played the role in preventing charge carrier recombination. The photocatalytic stability and trapping test of active radical for MB and MO degradation over heterostructure 0.5% Pt/ZnO nanocomposites were evaluated and discussed according to the experimental results.

The interphase distribution of lanthanide(III) ions between aqueous solutions of HNO₃ and solutions of tetrabutyldiglicolamide Bu₂C(O)CH₂OCH₂C(O)NBu₂ (1), compounds R₂P(O)CH₂OCH₂C(O)NBu₂, where R = Bu (2), R = Ph (3) and phosphoryl-containing podands R₂P(O)CH₂OCH₂P(O)R(_{2}^{1}), where R = R¹ = Bu (4); R = Bu, R¹ = Ph (5); R = R¹ = Ph (6) in 1,2-dichloroethane and ionic liquid—1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide—has been studied. Extraction of metal ions has been found to increase considerably in the presence of ionic liquid in organic phase. The stoichiometry of the extracted complexes has been determined and the influence of HNO₃ concentration in aqueous phase and the structure of the extractant on the efficiency of metal ions extraction into organic phase has been considered.

Nanocrystalline bismuth ferrite was synthesized using spray pyrolysis and citrate combustion methods. BiFeO₃ samples were characterized by X-ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy. The citrate and spray pyrolysis samples of bismuth ferrite were tested as catalysts for the Fenton-like oxidative degradation of methyl orange. The effect of the synthesis method on the composition and morphology of bismuth ferrite particles and on the catalytic activity was established. The oxidative degradation of the dye in the presence of bismuth ferrite samples is satisfactorily described by pseudo-first order kinetics. The reaction rate constant for BiFeO₃ synthesized by spray pyrolysis is 0.0072 min^–1, while that for citrate BiFeO₃ is slightly lower: 0.0049 min^–1. The degree of degradation of methyl orange in 120 min is 7% without a catalyst, 62% in the presence of spray pyrolysis bismuth ferrite, and 51% in the presence of citrate bismuth ferrite.

The exhaustive halogenation of the β-positions of Cu(II)-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin using N-bromosuccinimide and N-chlorosuccinimide in dimethylformamide was carried out. Cu(II)-β-octachloro-(2,3,4,5,6-pentafluorophenyl)porphyrin was synthesized by the reaction of Cu(II)-5,10,15,20-tetra-(2,3,4,5,6-pentafluorophenyl)porphyrin with N-chlorosuccinimide in dimethylformamide. Using the complexation of β-octabromo-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin, β-octachloro-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin, and β-octachloro-5,10,15,20-tetra-(2,3,4,5,6-pentafluorophenyl)porphyrin with copper salts in dimethylformamide under mild conditions, the corresponding copper(II) complexes were obtained. The coordination reaction kinetics of β-octabromo-5,10,15,20-tetra-(2,6-difluorophenyl-porphyrin with copper chloride in dimethylformamide has been studied. The kinetic parameters of the reaction were calculated. The obtained compounds were identified by UV-Vis and ¹H NMR spectroscopies, mass spectrometry, and elemental analysis. X-ray powder diffraction patterns were obtained for a number of copper complexes.

The synthesis of neodymium carboxylates (neodecanoate and 3,5,5-trimethylhexanoate) and their application in developing Nd-loaded liquid organic scintillators are discussed. Neodymium carboxylates were obtained through a one-step synthesis (for 3,5,5-trimethylhexanoate) and a two-step synthesis (for neodecanoate). The composition of the synthesized compounds was confirmed using IR spectroscopy, elemental analysis, and MALDI-TOF MS. To incorporate neodymium carboxylates into a liquid organic scintillator, an additional solvent, tributylphosphate, was proposed. It was demonstrated that the scintillator’s light output, when using this solvent, is more than 60% higher up to a neodymium concentration of 12 g/L, compared to without it.

Single-phase samples of compounds occurring in La₂O₃–CoO–Sb₂O₅ system have been prepared by the thermal decomposition of nitrates, citrate method, and co-precipitation with hydrothermal treatment of precipitate followed by annealing. Their catalytic properties in CO oxidation reaction have been studied. It has been found that LaCo_1/3Sb_5/3O₆ catalyst with rosiaite structure obtained by co-precipitation method with hydrothermal treatment of precipitate followed by annealing showed the highest activity at low temperatures and stability in cyclic testing. This catalyst provides 90% conversion of CO at 265°C. The surface of LaCo_1/3Sb_5/3O₆ has been studied by XPS, TPD-O₂ (temperature-programmed desorption of oxygen), and IR spectroscopy. It has been shown that Langmuir–Hinshelwood model is the most probable mechanism of catalytic CO oxidation, which is accompanied by redox processes Co³⁺ ↔ Co²⁺ and Sb³⁺ ↔ Sb⁵⁺ with participation of surface-active forms of oxygen and vacancies. Antimony ions in this process play role of electron donor, whose increased concentration favors to the acceleration of adsorption processes and formation of active oxygen forms on the surface. The lack of sample surface contamination has been found during catalysis, which excludes the need of its regeneration.

It was for the first time that the heat capacity of β-pyrochlore complex oxides RbTe_1.5W_0.5O₆ and Rb_0.95Nb_1.375Mo_0.625O_5.79 was investigated by adiabatic vacuum calorimetry and differential scanning calorimetry in the temperature range T = (6–640) K. The obtained experimental data were used to calculate the standard thermodynamic functions: heat capacity (C_{{text{p}}}^{o}), enthalpy [H°(T)−H°(0)], absolute entropy [S°(T)], and Gibbs free energy [G°(T)−H°(0)] for the range from T → 0 to 640 K. The low-temperature (T < 50 K) heat capacity trends were analyzed in terms of the multifractal model, and a chain–layered structure topology of the studied compounds was established.

Mesoporous silica MCM-41 with a specific surface area of 1134 m²/g was prepared. It was used to manufacture supported mono- and bimetallic Pt–Ag catalysts with various metal ratios by incipient wetness impregnation. After the reductive high-temperature treatment of Pt–Ag catalysts, Pt and Ag metal nanoparticles contacting with one another were formed on the surface of the support as shown by X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS). The bimetallic catalysts showed an increased reactivity in TPR-H₂ compared to the relevant monometallic catalysts due to the interaction of AgO_x and PtO_y centers. The catalysts were tested in the reduction of 4-nitrophenol with sodium borohydride. A significant increase in 4-nitrophenol reduction rate over bimetallic catalysts was due to the synergistic effect of platinum and silver.

This work has solved the problem of manufacturing high-coercivity barium hexaferrite BaFe₁₂O₁₉ ceramic samples. A BaFe₁₂O₁₉ nanopowder with coercivity H_c = 445 kA/m was prepared by hydrothermal synthesis. Sintering was carried out at low temperature (900°C) to preserve the grains in a single-domain state. To perform sintering at such a low temperature, B₂O₃ or Bi₂O₃ was added to the hexaferrite. The effects of the amount and type of additive on the phase composition, microstructure, and magnetic properties of the sintered hexaferrite were studied. When Bi₂O₃ (in the form of 0.5, 1, or 3 wt % of Bi(NO₃)₃) was used, no changes in the phase composition occurred, while addition of B₂O₃ (in the form of 0.5, 1, or 3 wt % of H₃BO₃) resulted in a partial transformation of the hexaferrite to hematite α-Fe₂O₃. The average grain size of BaFe₁₂O₁₉ increased in response to increasing Bi₂O₃ or B₂O₃ concentration, but did not exceed the critical single-domain size. This provided for the high H_c values (370–420 kA/m) of the sintered samples, making them superior to most well-known brands of unsubstituted hexaferrites.

A series of chromophoric complexes Ni^II(3,6-Cat)(Phen) (1), Ni^II(3,6-Cat)(DPQ) (2), and Ni^II(3,6-Cat)(DPPZ) (3) (where 3,6-Cat is 3,6-di-tert-butylcatecholate dianion) has been synthesized using 1,10-phenanthroline (Phen), dipyrido[3,2-d:2',3'-f]quinoxaline (DPQ), and dipyrido[3,2-a:2',3'-c]phenazine (DPPZ). Chromophores 1–3 have a slightly distorted planar structure of the coordination environment and undergo photoinduced ligand-to-ligand intramolecular charge transfer (HOMO_donor → LUMO_acсeptor), thus demonstrating strong light absorption in visible and near-IR regions. Complexes 1–3 are characterized by high thermostability and complete transition to the vapor phase under reduced pressure conditions. Compound 1 has high volatility, which makes it a suitable candidate for further testing in the fabrication of optoelectronic devices by “evaporation–deposition” technology.