The electrochemical properties of an electrode material based on a high-capacity silicon/reduced graphene oxide composite are studied. It was determined that the optimal potentials for reversible insertion/extraction of lithium are in the range of 50–2000 mV. The discharge capacity is 980 mAh g–1 at the charge rate 0.3 C and discharge rate 1.0 C. The addition of vinylene carbonate to the electrolyte solution leads to the stabilization of the solid electrolyte layer on the electrode surface. The discharge capacity is 866 mAh g–1 at the 170th charge/discharge cycle.
Catalysts of carbon monoxide oxidation were synthesized by deposition of platinum on titanium nitride (TiN). Two substrates with an average particle size of 18 and 36 nm were obtained by hydrogen reduction of titanium tetrachloride in a stream of microwave plasma of nitrogen. The surface of the catalysts was studied by X-ray photoelectron spectroscopy (XPS). The CO oxidation rate on the 9-15 wt.% Pt loaded TiN catalysts was found to be 120 times higher than that on platinum black with a specific surface of 30 m2/g. Such catalysts are promising for use in catalytic air purification systems.
Catalysts of low-temperature carbon monoxide oxidation are obtained by depositing platinum clusters on surfaces of plasma-chemical titanium nitride. The catalyst surfaces are studied by means of X-ray photoelectron spectroscopy (XPES). It is shown that in the catalysts, platinum is not only in contact with a thin layer of titanium dioxide but in possible direct contact with titanium oxynitride as well. It is found that treating the catalyst with carbon monoxide does not result in the total reduction of platinum. When XPE spectra of the initial powders of titanium nitride are compared to those of the catalyst, it is shown that the oxide film on the nitride surface grows thinner when the catalyst is synthesized.
— A new technique has been proposed for TiO 2 synthesis via oxidative hydrolysis of TiN powder. We have examined the effect of factors determining the rate of TiN dissolution (temperature, concentration, and nature of the oxidant) on the phase composition and particle size of resulting TiO 2 powders and assessed the photocatalytic activity of the synthesized powders in comparison with commercially available photocatalysts.
A CO oxidation catalyst that includes Pt clusters applied on nanosized TiN supports with a particle size of 18 and 36 nm has been synthesized. The catalyst has been studied using TEM, X-ray powder diffraction, and XPS methods. It has been found that platinum clusters formed on the support surface are covered with a mixture of platinum and platinum oxide. The coherent scattering range of the Pt cluster is close to 8 nm on a support with titanium nitride particles of 18 nm. The catalytic properties in the reaction of CO oxidation at 295 K and low CO concentrations (<100 mg/m(3)) have been examined. It has been found that when the platinum content in the catalyst is 9 to 15 wt %, the CO oxidation rate is 120 times higher than that on platinum black with a specific surface area of 30 m(2)/g. The catalysts are promising for use in catalytic systems for air purification.
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.
Nanocatalysts containing platinum and palladium clusters have been synthesized on the basis of detonation nanodiamond, cubic silicon carbide, and titanium dioxide. Characteristic size of the Pt cluster was close to 4 nm on both nanodiamond (particle size 5 nm) and β-SiC (particle size 13 nm) supports. The catalysts show high catalytic activity in reactions of CO oxidation and photocatalytic oxidation of ethanol at room temperature and low concentrations (<100 mg m3). They are promising in photocatalytic air purification systems for domestic use.
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/m 3 ) 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 m 2 /g. The Pt/SiC catalyst containing 12 wt % Pt has been found to provide the maximum CO oxidation rate.
Binder effect on the stability specific capacitance and coulombic efficiency of the thin-film anodes for lithium-ion batteries based on a nanoscale oxidized silicon Si@SiO2 structures has been studied. It was shown that using of the lithiated Nafion allows one to improve the capacity characteristics of the thin-film anodes and their stability during the charge/discharge cycles compared with the widespread binders such as polyvinylidene fluoride and carboxymethyl cellulose.
Nanoparticles with a core-shell structure of Si@SiO2 with an average size of about 50 nm were obtained by plasma chemical synthesis through the decomposition of monosilane. Electrochemical impedance spectroscopy (EIS) was used to study the behavior of anodes based on the composite Si@SiO2 during the cyclic charge/discharge. Based on the results of Si@SiO2 anodes studies by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) in conjunction with thermodynamic modeling (TM), assumptions were made about chemical and electrochemical processes occurring during prolonged cycling in the electrolyte 1 M LiPF6 in ethylene carbonate/diethyl carbonate (1:1 v/v). (C) 2016 Elsevier Ltd. All rights reserved.
TIOKRAFT experimental photocatalytic recyclers are suggested for cleaning and disinfection of indoor air in various facilities, including hospitals. It is demonstrated that these recyclers can be effectively used to purify air from volatile organic pollutants, aerosols, and fungal and bacterial microflora. The photocatalytic recyclers reduce microbiological contamination of the air in hospital facilities by an order of magnitude. Thus, the recyclers can be considered as promising agents of protection against nosocomial infections.
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 CO 2 ) 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 (H 2 CO) are worth mentioning apart from C1–C3 hydrocarbons.
The conditions for the formation of the particle-size and phase composition of titanium dioxide upon the oxidation of titanium tetrachloride in a stream of oxygen-containing microwave discharge plasma have been studied. The possibility of controlling the particle size of the resulting powder in the range of 50–100 nm by changing various operating parameters has been shown. The conditions for obtaining a nearly single-phase powder of the anatase or rutile modification have been found.
The effect of operating parameters of the oxidation of aluminum powder in a stream of air microwave plasma on the particle size of the obtained Al 2 O 3 has been studied. The possibility of improving the particle size of the powder by pretreatment the starting aluminum with chemicals activating particle combustion in a reactor has been investigated. Ways of controlling the particle size of produced aluminum oxide nanopowders in the range of 20–80 nm have been found.