共查询到20条相似文献,搜索用时 11 毫秒
1.
A. B. Velichenko V. A. Knysh T. V. Luk’yanenko D. Devilly F. I. Danilov 《Russian Journal of Applied Chemistry》2008,81(6):994-999
Fundamental aspects of electro deposition of PbO2-based composites containing titanium dioxide particles were studied. The content of the dispersed phase in the composite depends on the electrolyte composition and deposition conditions. Incorporation of titanium dioxide particles into PbO2 leads to significant changes in the morphology and structure of the deposit. 相似文献
2.
Compound Zn2SnO4 was synthesized by a hydrothermal method in which SnCl4 · 5H2O, ZnCl2 and N2H4 · H2O were used as reactants. Composite Zn2SnO4/C was then synthesized through a carbothermic reduction process using the as-prepared Zn2SnO4 and glucose as reactants. Comparing to the pure Zn2SnO4, some improved electrochemical properties were obtained for composite Zn2SnO4/C. When doped with 15% glucose, the composite Zn2SnO4/C showed the best electrochemical performance. Its first discharge capacity was about 1500 mA h g−1, with a capacity retain of 500 mA h g−1 in the 40th cycle at a constant current density of 100 mA/g in the voltage range of 0.05–3.0 V. There were also some differences
displayed in their cyclic voltammogram. 相似文献
3.
S. A. Kirillova V. I. Almjashev V. V. Gusarov 《Russian Journal of Inorganic Chemistry》2011,56(9):1464-1471
Phase equilibria in a miscibility gap of the SiO2-TiO2 system were studied. A visual polythermal analysis and annealing of samples were performed in a Galakhov microfurnace. The
microstructure and composition of the obtained samples were investigated by scanning electron microscopy and electron probe
microanalysis. A critical analysis of the experimental data was made. Thermodynamically optimized based on the sub-regular
solution model, a phase diagram of the SiO2-TiO2 system was constructed. 相似文献
4.
The electrochemical oxidation of dilute aqueous solutions of pentachlorophenol (PCP) using Ti/SnO2 as an electrocatalytic material has been investigated. The studies were carried out in a two-compartment electrochemical
cell at three different current density values (10, 30 and 50 mA cm–2) at 25 °C and using 20 mg L–1 of PCP in 0.1 M NaOH (pH 10) as supporting electrolyte. The PCP concentration and the by-products of the oxidized solution
were monitored during the oxidation process using UV and HPLC techniques. For the three current densities investigated it
was found that the rate of PCP elimination depends only on the specific electrical charge. Likewise, the oxidation mechanism
was proved to occur through the participation of adsorbed hydroxyl radicals (·OH) formed on the SnO2 surface, whatever the current density used. However, as the applied current density was increased, a current efficiency lower
than 2% was obtained, which is due to mass transfer limitations. In addition, it was observed that the PCP was mineralized
to CO2 with conversion percentages as high as 92% and at current density values as low as 10 mA cm–2. The PCP degradation produces two other by-products of oxidation (<10%), namely carboxylic acids, which are non-toxic compounds.
Electronic Publication 相似文献
5.
N. I. Sorokin 《Russian Journal of Electrochemistry》2016,52(1):91-93
The SnO2|ZhK-440|SnO2 system, where the ZhK-440 is a liquid crystal mixture consisting of 2/3 parts of p-butyl-p'-methyloxyazoxybenzene and 1/3 part of p-butyl-p'-heptanoyloxyazoxybenzene, was studied by impedance spectroscopy. The impedance spectrum of the system contained the contributions from electric conductivity and bulk and electrode polarizations. The models of bulk and electrode impedance were discussed. 相似文献
6.
B. Szczepaniak J. Goralski J. Grams W. Maniukiewicz T. Paryjczak 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(12):1992-1996
A series of ZrO2-TiO2 mixed oxides with different weight ratios (5, 20, and 30% ZrO2) were prepared by wet impregnation of TiO2-P25 Degussa with certain amounts of ZrO(NO3)2·6H2O (Fluka) dissolved in deionised water. The samples were characterized by the XRD,
,
,
, and BET methods. An increase in ZrO2 content shifted the phase transition temperature (anatase into rutile) toward higher temperatures. X-ray diffraction using
an Anton Paar XRK900 reactor chamber indicated that, in the case of samples containing ZrO2, an additional diffraction peak appeared after cooling down to 25°C. This peak could be attributed to a polymorph of TiO2 such as in the single crystal of anatase or hexagonal form of TiO2 which appears in the presence of ZrO2. Generally, the preparation of dioxide systems can modify the properties of pure compounds or generate new catalytic sites
as a result of strong interaction between ZrO2 and TiO2 oxides. The binary systems exhibit advantages like strong acidity, extended specific surface area, and high thermal stability
in comparison with TiO2.
The article is published in the original. 相似文献
7.
Virginie Gueu Hongpeng You Tomokatsu Hayakawa Masayuki Nogami 《Journal of Sol-Gel Science and Technology》2007,41(3):231-236
Fluorescence and spectral hole burning properties of Eu3+ ions were studied in nanocrystals-precipitated SnO2-SiO2 glasses. The glasses were prepared to contain various amount of Eu2O3 using the sol-gel method, in which SnO2 nanocrystals were precipitated by heating in air. In the glasses containing Eu2O3 less than 1%, the Eu3+ ions were preferentially doped in the SnO2 nanocrystals and their fluorescence intensities were enhanced by the energy transfer due to the recombination of electrons
and holes excited in SnO2 crystals. The SnO2 nanocrystals-precipitated glasses exhibited the persistent spectral holes with the depth of ∼25% of the total fluorescence
intensities of the Eu3+ ions. With the increasing Eu2O3 concentration, the amount of SnO2 nanocrystals decreased and the Sn4+ ions formed the random glass structure together with the silica network. This structure change induced the fluorescence intensities
and the hole depth to decrease. 相似文献
8.
M. V. Vinokurova A. A. Vinokurov L. E. Derlyukova 《Russian Journal of Electrochemistry》2009,45(4):439-443
Chemisorption of SO2 and O2 at Pt-modified SnO2 is studied by using the vacuum static method, with simultaneous recording of electrical conductivity, over the 22 to 300°C temperature range. The SnO2 surface modification results in the increasing of SO2 adsorption and weakening of the gas-surface bonding. The chemisorption enhances the samples’ electrical conductivity. The surface pretreatment with oxygen leads to the decreasing of the successive SO2 chemisorption. 相似文献
9.
A. A. Shutilov G. A. Zenkovets S. V. Tsybulya V. Yu. Gavrilov G. N. Kryukova 《Kinetics and Catalysis》2012,53(3):409-418
The effect of the microstructure of titanium dioxide on the structure, thermal stability, and catalytic properties of supported CuO/TiO2 and CuO/(CeO2-TiO2) catalysts in CO oxidation was studied. The formation of a nanocrystalline structure was found in the CuO/TiO2 catalysts calcined at 500°C. This nanocrystalline structure consisted of aggregated fine anatase particles about 10 nm in size and interblock boundaries between them, in which Cu2+ ions were stabilized. Heat treatment of this catalyst at 700°C led to a change in its microstructure with the formation of fine CuO particles 2.5–3 nm in size, which were strongly bound to the surface of TiO2 (anatase) with a regular well-ordered crystal structure. In the CuO/(CeO2-TiO2) catalysts, the nanocrystalline structure of anatase was thermally more stable than in the CuO/TiO2 catalyst, and it persisted up to 700°C. The study of the catalytic properties of the resulting catalysts showed that the CuO/(CeO2-TiO2) catalysts with the nanocrystalline structure of anatase were characterized by the high-est activity in CO oxidation to CO2. 相似文献
10.
11.
Žaneta Dohnalová Petra Šulcová Miroslav Trojan 《Journal of Thermal Analysis and Calorimetry》2010,101(3):973-978
The main aim of this work was to synthesize the magnesium orthostannate doped by terbium cations and tested whether these
materials can be used for colouring of the different materials, e.g. organic binder and ceramic glazes. Initial composition
of pigments was counted according the general formula 2MgO(1 − x)SnO2–xTbO2, where values of x varied from 0.1 to 0.5 in 0.1 steps. The simultaneous TG/DTA measurements of mixture containing tin oxide, magnesium carbonate
hydroxide and terbium oxide showed that the formation of a new compound started at temperature 1,029 °C, but single-phase
system was not prepared. Granulometric compositions of samples that were prepared by calcining at temperatures 1,300–1,400 °C
are characterized by values of median (d
50) in range 4–8 μm. The calcining temperature 1,500 °C caused the increase of the particle sizes at around 12 μm. The composition
of sample 2MgO–1.5SnO2–0.5TbO2 and heating temperature 1,500 °C are the most suitable conditions for preparation of colourfully interesting pigment that
can be recommended also for colouring of ceramic glazes. Especially, for colouring of decorative lead containing glaze G 07091
containing 5 wt% of PbO and 8 wt% of Al2O3. 相似文献
12.
New cesium-conducting solid electrolytes based on cesium monoferrite in the Fe2O3-TiO2-Cs2O system are synthesized and studied. It is found that the introduction of titanium dioxide significantly reduces the electronic
component of conductivity, which prevails in pure CsFeO2, and raises the ionic conductivity. The latter becomes predominant with increasing concentration of TiO2. The effect of dimensional factor on the characteristics of electrolyte is shown. The optimal compositions studied have very
high cesium-cationic conductivity: it is above 10−2 S cm −1 at 300°C. 相似文献
13.
T. V. Belysheva G. N. Gerasimov V. F. Gromov E. Yu. Spiridonova L. I. Trakhtenberg 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(9):1554-1559
The conductivity of films consisting of a mixture of SnO2 and In2O3 nanocrystals at 200–500°C was studied. Based on the experimental data, it was assumed that in films containing less than
20 wt % In2O3, the current flows along SnO2 nanocrystals. A model of conductivity in these films is presented; it includes an electron transfer from In2O3 to SnO2, which forms positively charged In2O3 nanocrystals that contact the negatively charged SnO2 nanocrystals. In the presence of In2O3 nanocrystals, the activation energy of the electron transfer between SnO2 nanocrystals decreased substantially because of a decrease in the barrier of electron transfer between SnO2 crystals under the action of the negative charge. As a result, a percolation cluster of charged SnO2 crystals formed. At high contents of In2O3 (over 20 wt %), the conductivity increased dramatically. The curve of the temperature dependence of conductivity changed
because of the appearance of a percolation cluster of In2O3 nanocrystals, in which the current passed. The conductivity of a mixed film of this kind differed from that of the nanocrystalline
film of pure In2O3. 相似文献
14.
SnO2/B2O3 samples were produced by a reaction between SnCl4, H3BO3, and (NH2)2CO in a boiling aqueous solution. The Sn: B molar ratio in these samples was 1: 1, 1: 2, and 1: 3. The phase composition and degree of crystallinity of these materials was studied. The surface acidity of the samples was analyzed by the method based on a temperature-programmed reaction of dehydration of 2-methyl-3-butyn-2-ol. Thermal transformations of SnO2/B2O3 samples were examined by means of differential-thermal analysis. 相似文献
15.
Hierarchical porous tin dioxide has been successfully prepared through a fast one-pot template-free synthesis route. The boiling
of the mixture of alcohol and glycerol can be utilized to generate nanopores in the SnO2 monolith. Polycrystalline hierarchical SnO2 with well proportioned composition has also been obtained in the pore walls of tin dioxide. 相似文献
16.
B. G. Golovkin 《Russian Journal of General Chemistry》2005,75(12):1857-1863
Gravimetry in combination with X-ray phase analysis, X-ray crystallography, and X-ray densitometry were used to determine the contents of V5+, V4+, and Ti4+ ions and vacancies in solid solutions formed by the reaction of V2O5 with TiO2 in air at atmospheric pressure. 相似文献
17.
Oswald S Behr G Dobler D Werner J Wetzig K Arabczyk W 《Analytical and bioanalytical chemistry》2004,378(2):411-415
The effect of surface segregation in Sb- and In-doped SnO2 fine-grained powders has been analyzed in comparison with single-crystalline samples. The kinetics and thermodynamics of the Sb and In segregation processes were studied as a function of annealing temperature by X-ray photoelectron spectroscopy (XPS) after annealing in an oxygen-containing atmosphere. Significant differences between diffusion and segregation were revealed for doped powders and single crystals, obviously because of simultaneous diffusion and particle-growth processes proceeding during annealing of powders. For doped single crystals the thermodynamic equilibrium is approached after 24 h annealing above 850 °C and at 1000 °C for Sb and In, respectively. Higher effective activation energies of diffusion are observed for doped powders and the thermodynamic equilibrium is not achieved under technologically relevant annealing conditions. On the basis of dopant profile measurements anomalies in the electrical resistivity at 300 °C of Sb-doped SnO2 powders annealed at 700 and 900 °C were attributed to an Sb-depleted zone formed beneath the segregated surface during the kinetic regime. To achieve optimum resistivity behavior for commercial application, inhomogeneous doping of powders must be avoided by appropriate preparation steps. 相似文献
18.
Solid solutions based on cesium monogallate CsGaO2 are synthesized in the Ga2O3-TiO2-Cs2O system. Their crystalline structure and also temperature and concentration conductivity dependences are studied. The cesium cation character of conductivity is confirmed. The most conducting samples contain an excess of cesium oxide and have the structure of high-temperature γ-modification of KAlO2. Their specific conductivity is (5.0–6.7) × 10?3 S cm?1 at 400 °C, (2.5–5.0) × 10?2 S cm?1 at 700°C at the activation energy of 33–35 kJ/mol?1. 相似文献
19.
This work is focused on the role of gold and Al3CrO6 support for physicochemical properties, and catalytic activity of supported nickel catalysts in partial oxidation of methane
(POM). Catalysts, containing 5% Ni and 5% Ni-2% Au active phases dispersed on mono- (Al2O3, Cr2O3) and bi-oxide Al3CrO6 support, were investigated by TPR, BET and XRD methods, and the activity tests in POM reaction were carried out. Bimetallic
Ni-Au catalysts dispersed on Al3CrO6 support remained highly stable and active. The amorphous binary oxide Al3CrO6 can stabilize considerable amount of Cr4+, Cr5+, and Cr6+ species in Ni-Au/Al3CrO6 catalyst network during its calcination in the air. Nickel supported on binary oxide Ni/Al3CrO6 can form Ni(III)CrO3 bi-oxide phase in reductive conditions. During TPR H2 reduction of Ni-Au/Al3CrO6 catalyst chromium(II) oxide Cr(II)O phase is observed. After POM reaction the existence of bimetallic Au-Ni alloy was experimentally
confirmed on mono-oxide Al2O3 support surface, but its formation was not identified on bioxide Al3CrO6 support.
Published in Russian in Kinetika i Kataliz, 2009, Vol. 50, No. 1, pp. 149–156.
The article is published in the original.
Based on a report at the VII Russ. Conf. on Mechanisms of Catalytic Reactions (with international participation), St. Petersburg,
July 2–8, 2006. 相似文献
20.
Franck Dumeignil Danhong Wang Eika W Qian Shinichi Inoue Akinori Muto Toshiaki Kabe Atsushi Ishihara 《Research on Chemical Intermediates》2005,31(9):819-832
The first part of this paper deals with the morphology of the MoS2 phase and its oxide precursor, the MoO3 phase, mainly from a geometrical point of view. After giving a brief review of the literature describing the structure of
these compounds, Mo densities in both phases were calculated along various crystallographic planes. Further, using structural
models recently proposed by others, Mo densities in MoS2 were also calculated in the case of an epitactic growth on γ-Al2O3 and TiO2 model surfaces. Then, the calculated Mo densities were compared with experimental results (Mo density when HDS activity is
maximal) previously obtained for catalysts constituted of MoS2 supported on a low SSA TiO2, a high SSA TiO2 and a conventional γ-alumina. It was suggested that either on alumina or titania the MoS2 phase is growing as (100) MoS2 planes. However, while on the alumina the optimal MoS2 phase might be constituted of dispersed MoS2 slabs covering only a part of the alumina surface (2.9–3.9 Mo atoms/nm2), on titania the optimal MoS2 phase might be constituted of a uniform MoS2 monolayer (5.2 atoms/nm2 for the high SSA titania, which is equal to the Mo density of a perfect MoS2 (100) plane). This difference may originate in the creation of a 'TiMoS' phase enhancing the S atoms mobility over Mo/TiO2-sulfided catalysts. Indeed, while in the case of a γ-alumina carrier the active sites (labile S atoms) are located on the edge of MoS2 slabs making the ratio Moedge/Mototal a crucial parameter for the catalytic performances, in the case of a titania carrier the labile sulfur atoms might be statistically
distributed all over the TiMoS active phase. Further, the higher Mo density observed over the high SSA titania (5.2 atoms/nm2) when compared to that over the low SSA titania (4.2 atoms/nm2) was supposedly due to the pH-swing method advantageously used to prepare the former carrier. Indeed, this method allows
giving a solid with enhanced mechanical properties providing a good stability to the derived catalysts under experimental
conditions. In addition, this TiO2 carrier exhibits a great homogeneity, with a surface structure substantially uniform, which might be adequate for a long-range
growth of (100) MoS2 slabs. 相似文献