Yu. V. Shubin

Fluorinated cage multiwall carbon nanoparticles

Abstract Multiwall carbon nanoparticles from the inner part of a deposit grown onto a cathode in an arc-discharge condition were fluorinated at room temperature using volatile fluoride BrF 3 . The sample produced was characterized by means of X-ray diffraction (XRD), infrared (IR) and X-ray photoelectron spectroscopy (XPS). These methods point to the presence of covalent C–F bonds in the sample with retention of the sp 2 -hybridizated carbon atoms composing the cage tubular or quasi-spherical shells. Transmission electron microscopy (TEM) indicated a decrease of cage nanoparticles in the fluorinated material relative to the pristine sample that may be connected with unrolling the nanotubes during fluorination.

Co-Pt bimetallic catalysts for the selective oxidation of carbon monoxide in hydrogen-containing mixtures

The performance of a Co-Pt powder and of Co-Pt catalysts supported on γ-Al2O3 and on the graphite-like carbon material Sibunit in selective CO oxidation in hydrogen-containing mixtures is considered. Fine particles of metal-metal solid solutions and intermetallides were obtained by the decomposition of a Co- and Pt-containing double complex salt in a hydrogen atmosphere at ∼400°C. As compared to their Pt and Co monometallic counterparts, the bimetallic catalysts are more active and allow the CO concentration in hydrogen-containing mixtures to be reduced from 1 to 10−3 vol %. This effect is likely due to the formation of bimetallic particles of a Co-Pt solid solution on the support surface.

Synthesis and Structure of Binary Complexes of Platinum Group Metals — Precursors of Metallic Materials

This paper reviews the results of structural studies of binary complexes whose cationic part contains cobalt, rhodium, iridium, ruthenium, and chromium chloropentammne. The structure of these compounds is discussed in the light of the design of new multicomponent precursor compounds. Data are given on the chemical and phase compositions of the polymetallic powders resulting from the thermal decomposition of the compounds studied.

One-pot reductive amination of aldehydes with nitroarenes over an Au/Al2O3 catalyst in a continuous flow reactor

One-pot reductive amination of aromatic and aliphatic aldehydes with nitroarenes over an Au/Al2O3 catalyst in a continuous flow reactor using molecular hydrogen as a reducing agent was performed. Various secondary aromatic amines were obtained in good to excellent yields.

Growth of MoS2 layers on the surface of multiwalled carbon nanotubes

Molybdenum disulfide has been deposited on the surface of multiwalled carbon nanotubes synthesized through arc vaporization of graphite. As shown by transmission electron microscopy, extended MoS2 layers have been formed on the surface of the carbon nanoparticles. According to x-ray diffraction results, the crystallinity of the MoS2 layers in the composites improves with increasing annealing temperature. Free MoS2 particles can be removed from the composites by centrifugation in bromoform.

Low-temperature oxidation of carbon monoxide on Pd(Pt)/CeO2 catalysts prepared from complex salts

Catalysts containing cerium oxide as a support and platinum and palladium as active components for the low-temperature oxidation of carbon monoxide were studied. The catalysts were synthesized in accordance with original procedures with the use of palladium and platinum complex salts. Regardless of preparation procedure, the samples prepared with the use of only platinum precursors did not exhibit activity at a low temperature because only metal and oxide (PtO, PtO2) nanoparticles were formed on the surface of CeO2. Unlike platinum, palladium can be dispersed on the surface of CeO2 to a maximum extent up to an almost an ionic (atomic) state, and it forms mixed surface phases with cerium oxide. In a mixed palladium-platinum catalyst, the ability of platinum to undergo dispersion under the action of palladium also increased; as a result, a combined surface phase with the formula PdxPtyCeO2 − δ, which exhibits catalytic activity at low temperatures, was formed.

The atomic and electron structure of ZrO2

The atomic structure of amorphous and crystalline zirconium dioxide (ZrO2) films is studied using X-ray diffraction and extended X-ray absorption fine structure techniques. The electron structure of ZrO2 is experimentally determined using X-ray and UV photoelectron spectroscopy, and the electron energy band structure is theoretically calculated using electron density functional method. According to these data, the valence band of ZrO2 consists of three subbands separated by an ionic gap. The upper subband is formed by the O2p states and Zr4d states; the medium subband is formed by the O2s states; and the narrow lower subband is formed predominantly by the Zr4p states. The bandgap width in amorphous ZrO2, as determined using the electron energy loss spectroscopy data, amounts to 4.7 eV. The electron band structure calculations performed for a cubic ZrO2 phase point to the existence of both light (0.3m0) and heavy (3.5m0) holes, where m0 is the free electron mass. The effective masses of band electrons in ZrO2 fall within (0.6–2.0)m0.

Synthesis, crystal structure, and thermal properties of [Pd(NH3)4][AuCl4]2

AbstractThe double complex salt [Pd(NH3)4][AuCl4]2 was synthesized and studied by X-ray diffraction: a = 7.5234(6) Å, b = 7.7909(5) Å, c = 8.0247(6) Å, α = 108.483(2)°, β = 106.497(2)°, γ = 99.972(3)°, V = 409.43(5) Å3, space group P % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVy0df9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% aIXaaaaaaa!361B!

Synthesis of unsaturated secondary amines by direct reductive amination of aliphatic aldehydes with nitroarenes over Au/Al2O3 catalyst in continuous flow mode

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