E. N. Kurkin

Phase transformations in nanostructural anatase TiO2 under shock compression conditions studied by Raman spectroscopy

Shock-wave-induced phase transformations in nanostructural titanium dioxide TiO2 (anatase) powders of two types have been studied by Raman spectroscopy. It is established that, at a shock-wave compression to 42 GPa, anatase particles can either transform into a columbite phase or exhibit amorphization.

Correlation between the Eg(1) oscillation frequency and half-width of the (101) peak in the X-ray diffraction pattern of TiO2 anatase nanoparticles

It is found that the frequency of the Eg(1) oscillation in the Raman spectrum of TiO2 anatase nanoparticles increases linearly with the half-width of the (101) peak in the X-ray diffraction pattern.

Synthesis and properties of a platinum catalyst supported on plasma chemical silicon carbide

A CO oxidation catalyst based on β–SiC and Pt nanoparticles has been synthesized and studied. The average size of Pt clusters on the surface of the plasma-chemical silicon carbide nanoparticles is close to 4 nm. It has been found that the rate of the CO oxidation reaction at low concentrations (100 mg/m3) in air at room temperature over the catalyst based on platinum and silicon carbide nanoparticles is 60–90 times that over a platinum black-based catalyst with a specific surface area of 30 m2/g. The Pt/SiC catalyst containing 12 wt % Pt has been found to provide the maximum CO oxidation rate.

Synthesis and properties of a CO oxidation catalyst based on plasma-chemical silicon carbide, titanium dioxide, and palladium

A catalyst based on plasma-chemical β-SiC and TiO2 with a palladium content of 10 wt % has been synthesized. The dependence of the rate of the CO oxidation reaction at room temperature and low CO concentrations (less than 100 mg/m3) on the β-SiC content has been studied. It has been found that with a β-SiC content of 8 to 10 wt %, the catalyst has a maximum reaction rate, which is three times that on a catalyst based on pure TiO2 including palladium clusters. The catalysts are promising for use in catalytic and photocatalytic air purification systems.

Thermally stimulated transformations in brookite-containing TiO2 nanopowders produced by the hydrolysis of TiCl4

TiO2 nanopowder is produced by the low-temperature hydrolysis of TiCl4. The phase composition of the sample is found to form at a hydrolysis temperature of 30–38°C. Low-temperature annealing (up to 440°C) increases the degree of crystallinity of the phases present in the sample (anatase, brookite) and only weakly affects their ratio. At 500°C, the sample consists of three phases: rutile is detected apart from anatase and brookite. Brookite begins to fail at 600°C; at 700°C, crystalline brookite fails completely.

On the factors determining the pyrophoric stability of tungsten nanopowder obtained by plasma-chemical pyrolysis of W(CO)6

Nonpyrophoric tungsten powders with an average particle size of about 30 nm were obtained by pyrolysis of tungsten hexacarbonyl in a flow of microwave discharge nitrogen plasma. It is found that these powders are stable in air up to 300°C. The reason for such stability is that the structure of powder particles is of the core-double shell type, in which the metal core is covered with an oxide film approximately 1 nm in thickness, coated in turn with roentgenoamorphous layer consisting of carbon, oxygen, and nitrogen atoms. It is also established that the powders under investigation mainly release carbon oxides (CO and CO2) and water into the gas phase upon heating in vacuum. Among the molecules present in the gas phase in small concentrations, nitrogen monoxide (NO) and formaldehyde (H2CO) are worth mentioning apart from C1–C3 hydrocarbons.

Manifestation of the effect of strong metal-support interaction in a Pt/TiO2 rutile catalyst

Pt/TiO2 catalysts supported on ultradispersed rutile are prepared. The effect of strong metal-support interaction (SMSI) in these catalysts is more pronounced than in Pt/TiO2 catalysts with greater fractions of an anatase phase in the support. Mild oxidation of the rutile catalyst eliminates the SMSI effect.

Low-Temperature Oxidation of Carbon Monoxide: The Synthesis and Properties of a Catalyst Based on Titanium Dioxide, Nanodiamond, and Palladium for CO Oxidation

A catalyst based on TiO2 and nanodiamond with a 10 wt % palladium content of the catalyst was synthesized. The effect of the nanodiamond content on the catalytic properties in a reaction of CO oxidation at room temperature and low concentrations of CO (<100 mg/m3) was studied. It was established that, at a nanodiamond content of the catalyst from 7 to 9 wt % and a palladium content of 10 wt %, the rate of CO oxidation reached a maximum, and it was higher by a factor of 2.5 than the rate of CO oxidation on a catalyst based on pure TiO2, which included palladium clusters. With the use of transmission electron microscopy, XRD X-ray diffractometry, and X-ray photoelectron spectroscopy, it was found that the clusters of palladium covered with palladium oxide with an average cluster size of 4 nm were formed on the surface of the TiO2 carrier. It was assumed that the catalyst synthesized is promising for applications in catalytic and photocatalytic air-cleaning systems.

Prospects for Using Photocatalytic Air Cleaning Technology to Provide Safety of Sevoflurane Application to Parturition Anesthesia in Obstetric Hospitals

The product composition of photocatalytic oxidation of vaporized sevoflurane, a next-generation fluorinated inhalation anesthetic, has been studied. It has been found that the final products of oxidation are carbon dioxide and hydrogen fluoride. The possibility of complete chemical absorption of the evolved hydrogen fluoride by a lime absorber during the course of the photocatalytic reaction has been shown. A safe scheme for using photocatalysis is recommended for purifying air to remove vapors of halogen-containing anesthetics under medical hospital conditions.

Composite formed upon the ultrasonication of an aqueous suspension of graphite oxide–titanium dioxide

A technique is developed for obtaining a titania–graphite oxide composite with a high surface area in which the TiO2 particles are covered by graphite oxide. It is established that the experimental value of the composite specific surface area passes through a maximum at about 200°С, depending on the temperature of preliminary annealing in an inert atmosphere.