共查询到20条相似文献,搜索用时 15 毫秒
1.
V. K. Yatsimirskii N. P. Maksimovich O. Yu. Boldyreva N. V. Nikitina A. G. Telegeeva 《Theoretical and Experimental Chemistry》2005,41(5):318-322
We have studied the effect of small additives of Pt and Pd on the hydrogen sensitivity of semiconductor adsorption sensors
based on SnO2 and on the catalytic activity of sensor materials of the same composition in oxidation of hydrogen. We have shown that as
the amount of Pt or Pd increases, the catalytic activity increases and the sensitivity of the sensors passes through a maximum.
The results obtained are explained taking into account the hydrogen spillover phenomenon.
__________
Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 5, pp. 302–306, September–October, 2005. 相似文献
2.
E. A. Bondarenko S. A. Bondarenko N. I. Kargin V. F. Gromov T. V. Belysheva E. Yu. Spiridonova L. V. Mikhnev L. I. Trakhtenberg 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(6):987-991
Opal-like materials based on tin dioxide were prepared, and their structural and sensor characteristics were studied. The
optical transmission spectra of opal-like structures based on SnO2 were recorded, and the volume fraction occupied in them by tin dioxide was estimated. It was shown that structures based
on SnO2 contained a photon stop-zone in the visible spectrum range. The sensor properties of the materials toward CO and H2 were studied over the temperature range 375−425°C. The SnO2 samples studied had much higher sensitivity to CO compared with SnO2 materials without opal-like structures. 相似文献
3.
A. I. Buvailo L. P. Oleksenko N. P. Maksimovich I. P. Matushko A. P. Ripko V. P. Ruchko 《Theoretical and Experimental Chemistry》2010,46(3):153-157
The effect of cobalt additions on the electrical resistance of adsorption–semiconductor sensors based on nanosized SnO2 in air, their sensitivity to hydrogen, and the catalytic activity of the corresponding sensor materials in the oxidation
of H2 were studied. The extremal nature of the obtained relationships is explained by morphological features of the investigated
systems based on nanosized SnO2. 相似文献
4.
Tetrabutyl ammonium hydrogen sulfate is an ion-paring reagent that has similar properties with ionic liquid. Ionic liquids
belong to new branch of salts with unique properties that have ever increasing applications in electrochemical systems especially
lithium-ion batteries. For the first time, the effects of tetrabutylammonium hydrogen sulfate (TBAHS) as an electrolyte additive
in battery’s electrolyte was studied on the hydrogen and oxygen evolution overpotential and anodic layer formation on lead–antimony–tin
grid alloy of lead acid battery by using cyclic voltammetry and linear sweep voltammetry in aqueous sulfuric acid solution.
The grid surface morphology after cyclic redox reaction was studied by using scanning electron microscopy. The results show
that, by increasing TBAHS concentration in the electrolyte, hydrogen and oxygen overpotential were increased, and so the crystalline
structure of PbSO4 layer changed. Also, cyclic voltammogram on carbon–PbO paste electrode shows that with presence of TBAHS in the electrolyte,
oxidation and reduction peak current intensively increased and peak potential for oxidation and reduction of PbO were dependent
on TBAHS concentration. 相似文献
5.
T. S. Zyubina A. S. Zyubin Yu. A. Dobrovol’skii V. M. Volokhov Z. G. Bazhanova 《Russian Journal of Inorganic Chemistry》2011,56(11):1765-1774
The hydrogen migration over the surface of platinum clusters applied to the tin dioxide crystal surface has been modeled by
the density functional theory method within the generalized gradient approximation (GGA) under periodic conditions using a
projector-augmented plane-wave (PAW) basis set with a pseudopotential. It has been demonstrated that the dissociative adsorption
energy of a hydrogen molecule onto the Pt19 cluster surface is 1.6 eV. The movement of the hydrogen atom over the cluster surface is ∼0.4 eV more favorable than in the
bulk. The location of the hydrogen atom on the SnO2 substrate is 1.62 eV more favorable than that on the upper face of the Pt19 cluster. The barriers to migration of hydrogen atom over the surface of the platinum cluster applied to the SnO2 surface are within 0.1–0.2 eV. 相似文献
6.
Patel Sanjay V. Hobson Stephen T. Cemalovic Sabina Mlsna Todd E. 《Journal of Sol-Gel Science and Technology》2010,53(3):673-679
The responses of alkylamine functionalized organic bridged polysilsesquioxanes on chemicapacitive sensors to carbon dioxide
(CO2) are described operating at temperatures ranging from 15 to 50°C. These hybrid organic–inorganic network materials were synthesized
by the sol–gel polymerization of a mixture of a matrix monomer and functional monomer at various ratios followed by aging
and ink-jet deposition of the sol on each capacitive sensor. During exposure of the sensor to known concentrations of analyte,
the material’s capacitance was measured. From these changes in capacitance, detection limits ranging from 40 to 100 ppm were
calculated. Furthermore, a correlation was observed with increasing length of the alkyl chain in the amine monomer correlating
with an increase in CO2 sensitivity and a decrease in water sensitivity. These materials offer a new method for CO2 detection for building control systems or other low-power applications using low operating temperatures. 相似文献
7.
M. T. Ganzerli Valentini R. Stella L. Maggi 《Journal of Radioanalytical and Nuclear Chemistry》1989,132(2):349-357
A novel type of tin oxide and its cation exchange properties are described. The preparation of the oxide is rather unusual and consists in the precipitation of SnO·xH2O in the presence of sodium nitroprusside and its digestion in the presence of sodium nitrite. The final product is a partially reduced tin dioxide (PRTD) with one out of eight atoms of metal in the lower oxidation state of +2 and a great part of the bound water hydrogen replaced by sodium. Usual applications of commercially available tin dioxide exchangers can be extended to PRTD with remarkable advantages. 相似文献
8.
Mahadevaiah M. S. Abdul Galil M. S. Yogendra Kumar M. A. Sathish G. Nagendrappa 《Journal of Analytical Chemistry》2008,63(3):239-243
A simple, rapid, and economical spectrophotometric method is developed for the determination of sulfur dioxide in sugar and
air samples. The developed method is based on a red-brown peroxovanadate complex (λmax = 470 nm) produced in 2 M sulfuric acid when ammonium metavanadate is treated with hydrogen peroxide. Under fixed concentrations
of hydrogen peroxide and ammonium metavanadate, when sodium metabisulfite (Na2S2O5 = 2SO2) is added, it preferentially reacts with hydrogen peroxide producing sulfuric acid, and the unreacted hydrogen peroxide then
reacts with ammonium metavanadate; therefore, the concentration of sulfur dioxide is directly proportional to a decrease in
the concentration of the peroxovanadate complex. The stoichiometric ratio between hydrogen peroxide and ammonium metavanadate
as well as the stability constant of the complex are determined by the modified Job’s method and the respective values are
found to be 1: 1 and 2.5 × 104 mol−1 L, respectively. The system obeys Lambert-Beer’s law in the concentration range 3.57–64.26 ppm of sulfur dioxide. The molar
absorptivity, correlation coefficient, and Sandell’s sensitivity values are found to be 0.649 × 103 L mol−1 cm−1, 0.9908, and 0.1972 μg cm−2, respectively. The method is applied to the determination of sulfur dioxide present in commercial sugars and air samples.
The results obtained are reproducible with a standard deviation of 0.02–0.05. For method validation, sulfur dioxide is also
determined separately following the AOAC method for an air sample and the ICUMSA method for commercial sugars. The results
obtained by the developed and official methods are in good agreement.
The text was submitted by the authors in English. 相似文献
9.
E. A. Goodilin E. A. Pomerantseva D. A. Semenenko P. B. Kocherginskaya D. M. Itkis T. L. Kulova A. M. Skundin L. S. Leonova Yu. A. Dobrovol’skii M. N. Rumyantseva A. M. Gas’kov S. B. Balakhonov B. R. Churagulov Yu. D. Tretyakova 《Russian Chemical Bulletin》2008,57(5):1042-1053
Practical aspects of preparation and prospects for practical use of a series of the metal oxide whiskers were studied. The
procedures for the synthesis were proposed, and the phase composition, micromorphology, and electrochemical and sensor characteristics
of the macroscopic (up to 5–10 mm long) whiskers in the Ba-V-O, Ba-Mn-O, and Sn-O systems were analyzed. The electroconducting
BaV8O21-δ whiskers were prepared by the hydrothermal treatment. These whiskers possess stable electrochemical characteristics appropriate
for the development of novel secondary current sources. The protonated form of the Ba6Mn24O48 whiskers produced by the isothermal vaporization of chloride fluxes is a mixed conductor with the proton and electron conductivity
at a level of mS units at 25 °C. A new procedure by the thermal disproportionation of tin(ii) oxide under nitrogen was proposed for the growth of SnO2 whiskers of various morphology. The produced whiskers have substantial sensor sensitivity toward a series of toxic components
of the gaseous medium, such as nitrogen dioxide.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1023–1034, May, 2008. 相似文献
10.
T. S. Zyubina A. S. Zyubin Yu. A. Dobrovol’skii V. M. Volokhov Z. G. Bazhanova 《Russian Journal of Inorganic Chemistry》2011,56(9):1402-1409
The hydrogen adsorption, dissociation, and migration on the tin dioxide surface have been modeled by the density functional
theory method within the generalized gradient approximation (GGA) under periodic conditions using a projector-augmented plane-wave
(PAW) basis set with a pseudopotential. It has been demonstrated that dissociative chemisorption onto the tin dioxide surface
depends on the adsorption site and the surface structure and that there are places on the surface where dissociation can occur
with a low barrier of 0.1–0.2 eV to yield a primary isomer in which one of the hydrogen atoms is bound to the tin atom and
the other, to an oxygen atom; the second dissociation even at the same place is possible only if the primary isomer overcomes
a barrier of ∼1 eV and transforms to the secondary isomer with two O-H bonds. 相似文献
11.
Rumyantseva M. N. Bulova M. N. Kuznetsova T. A. Ryabova L. I. Gas'kov A. M. Loucaseau G. Labeau M. 《Russian Journal of Applied Chemistry》2001,74(3):434-439
Results of investigations aimed at creating a material possessing selective sensitivity to gaseous hydrogen sulfide are presented. Polycrystalline films of doped tin dioxide were obtained by pyrolysis of an aerosol of appropriate organometallic compounds. The effect of copper and nickel oxides on the electrical properties, actual structure, and composition of polycrystalline tin dioxide films was studied. The influence of trace amounts of gaseous H2S on the electrical conductivity of the films was analyzed in detail. 相似文献
12.
The reduction of chromium, nickel, and manganese oxides by hydrogen, CO, CH4, and model syngas (mixtures of CO + H2 or H2 + CO + CO2) and oxidation by water vapor has been studied from the thermodynamic and chemical equilibrium point of view. Attention was
concentrated not only on the convenient conditions for reduction of the relevant oxides to metals or lower oxides at temperatures
in the range 400–1000 K, but also on the possible formation of soot, carbides, and carbonates as precursors for the carbon
monoxide and carbon dioxide formation in the steam oxidation step. Reduction of very stable Cr2O3 to metallic Cr by hydrogen or CO at temperatures of 400–1000 K is thermodynamically excluded. Reduction of nickel oxide (NiO)
and manganese oxide (Mn3O4) by hydrogen or CO at such temperatures is feasible. The oxidation of MnO and Ni by steam and simultaneous production of
hydrogen at temperatures between 400 and 1000 K is a difficult step from the thermodynamics viewpoint. Assuming the Ni—NiO
system, the formation of nickel aluminum spinel could be used to increase the equilibrium hydrogen yield, thus, enabling the
hydrogen production via looping redox process. The equilibrium hydrogen yield under the conditions of steam oxidation of the Ni—NiO system is, however,
substantially lower than that for the Fe—Fe3O4 system. The system comprising nickel ferrite seems to be unsuitable for cyclic redox processes. Under strongly reducing conditions,
at high CO concentrations/partial pressures, formation of nickel carbide (Ni3C) is thermodynamically favored. Pressurized conditions during the reduction step with CO/CO2 containing gases enhance the formation of soot and carbon-containing compounds such as carbides and/or carbonates. 相似文献
13.
Rezaei Behzad Havakeshian Elaheh Hajipour Abdol R. 《Journal of Solid State Electrochemistry》2011,15(2):421-430
The aim of this study is to introduce the application of some acidic ionic liquids (ILs) as an electrolyte additive in lead-acid
batteries. A family of alkylammonium hydrogen sulfate ILs, which are different in the number of alkyl chain, is investigated
with the aim to compare their effects on the electrochemical behavior of Pb–Sb–Sn alloy in sulfuric acid solution. The hydrogen
and oxygen gas evolution potential and anodic layer characteristics were investigated employing cyclic and linear sweep voltammetric
methods. The morphological changes of the PbSO4 layer that formed on the electrode surface were confirmed using scanning electron microscopy. Also, potentiodynamic polarization
curves, electrochemical impedance spectroscopy, and an equivalent circuit analysis were used to evaluate the corrosion behaviors
of the Pb–Sb–Sn alloy in the presence of ILs. The obtained results indicate that hydrogen and oxygen evolution overpotential
of lead–antimony–tin alloy increases in the solution containing IL and mainly depends on the number of alkyl chain in alkylammonium
cation. It is clearly observed that the morphology of PbSO4 layer changes under the influence of ILs. The corrosion studies show an increase in corrosion resistance of lead alloy in
the presence of some ILs. Also, the electrochemical effects of ILs in conversion of PbSO4 to PbO2 and vice versa were investigated by carbon-PbO paste electrode. Cyclic voltammogram of carbon-PbO electrode shows that in
the presence of ILs, oxidation and reduction peak currents increase, while reversibility decreases. 相似文献
14.
K. J. Chen F. Y. Hung S. J. Chang S. J. Young Z. S. Hu S. P. Chang 《Journal of Sol-Gel Science and Technology》2010,54(3):347-354
The multi-compound ZITO transparent conductive oxide (TCO) thin films were synthesized using the sol–gel method. The ZITO
thin films with various volume ratios of ZnO to ITO (1:1, 2:1 and 9:1) were crystallized at different temperatures (600–700 °C).
The results showed that the crystalline characteristics and optical transmittance were mainly dependent on ITO content and
crystallization. Notably, the 650 °C Z9ITO film not only had better conductivity but also possessed excellent optical transmittance. In addition, the surface roughness
of the ZITO films and optoelectric properties of IZO (indium doped ZnO) films were analyzed to confirm the contribution of
indium dopants on the optical transmittance. Also, the ZITO films were subjected to the effects of indium and tin dopants
and this improved the related characteristics of ZnO films. 相似文献
15.
Rima Tarozaitė Loreta Tamašauskaitė Tamašiūnaitė Vitalija Jasulaitienė 《Journal of Solid State Electrochemistry》2009,13(5):721-731
Platinum–tin complexes were prepared by the reduction of Pt(IV) with Sn(II) in HCl media and studied by light absorption spectrometry,
X-ray photoelectron spectroscopy (XPS), and electron microscopy. The formation of three complexes, H3[Pt(SnCl3)5], H2[Pt(SnCl3)2Cl2], and H2[Pt3(SnCl3)8], depending on HCl and SnCl2 concentrations, has been shown. The glassy carbon (GC) electrode modified in the complexes solutions was found to be an electrocatalyst
for borohydride oxidation in a 1.0-M NaOH solution. Comparison of BH4
− electrooxidation on Pt and on GC modified with platinum–tin complexes has shown that catalytic hydrolysis of BH4
− did not proceed in the latter case in contrast to its oxidation on the Pt electrode, and only direct BH4
− oxidation has been observed in the positive potentials scan. The activity of Pt–Sn complexes for BH4
− oxidation changes with time and eventually decreases due to Sn(II), bound in the complex with Pt(II), oxidation by atmospheric
oxygen. The complexes may be renewed by addition of missing amounts of SnCl2 and HCl. 相似文献
16.
A carbon supported Pt–Sn electrocatalyst in the Pt/Sn atomic ratio 50:50 was prepared by the reduction of Pt and Sn precursors
with formic acid and thermally treated at 200 °C (i.e., in the presence of solid tin) and 500 °C (in the presence of molten
tin) in flowing hydrogen. In the absence of thermal treatment, X-ray diffraction (XRD) analysis showed a solid solution of
Sn in the face centered cubic (fcc) Pt and SnO2. After thermal treatment, the formation of a main phase of hexagonal PtSn (niggliite) and a secondary phase of cubic Pt3Sn was observed in the Pt50Sn50 catalyst. The relative amount of the PtSn phase increased with increasing thermal treatment
temperature. The presence of molten tin gave rise to the formation of some big particles during annealing at 500 °C. The activity
for the ethanol oxidation reaction (EOR) of the as-prepared catalyst was higher than that of both thermally treated catalysts
and Pt75Sn25/C and Pt50Ru50/C by E-TEK. The higher activity for the EOR of the as-prepared Pt–Sn catalysts was ascribed to
the presence of a large amount of SnO2.
Dedicated to Teresa Iwasita’s 65th birthday. 相似文献
17.
A study was carried out on the properties of Ni/Al2O3 and Cu-ZnO/Al2O3 composites supported on ceramic honeycomb monoliths made from synthetic cordierite in the carbon dioxide conversion of methane
and the partial oxidation of methanol. The structured nickel-alumina catalysts are significantly more efficient than the conventional
granulated catalysts. The improved working stability of these catalysts was achieved by adjusting the acid-base properties
of the surface by introducing sodium and potassium oxides, which leads to inhibition of surface carbonization. The hydrogen
yield was close to 90% in the partial oxidation of methanol with a stoichiometric reagent ratio in the presence of the Cu-ZnO/Al2O3/cordierite catalyst. A synergistic effect was found, reducing the selectivity of CO formation in the presence of the Cu-ZnO
catalyst relative to samples derived from the individual components Cu and ZnO.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 5, pp. 299–306, September–October, 2007. 相似文献
18.
WANGShu-rong WUShi-hua SHIJuan ZHENGXiu-cheng 《高等学校化学研究》2005,21(1):17-20
Nanosized tin dioxide particles were prepared by sol-gel dialytic processes with tin(Ⅳ) chloride and alcohol as start materials. The nanoparticles of tin dioxide were charactered by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET. The results show that the average diameter of tin dioxide particles dried at 353 K was about 2nm. Even if the tin dioxide particles were calcined at 873 K, the average diameter of particles was less than 10 nm. The removal of Cl^- was solved by using this kind of method. The mechanism of the formation of tin dioxide nanosized particles was proposed and analyzed in this paper. We also measured the sensitivity of the sensor based on the tin oxide powder calcined at 673K to NH3, alcohol, acetone, hexane and CO. The gas-sensing performance results indicate that this sensor has a higher sensitivity to alcohol and acetone, and selectivity for NH3, hexane and CO at an operating temperature of 343 K. 相似文献
19.
Haili Pang Changting Huang Jinhua Chen Bo Liu Yafei Kuang Xiaohua Zhang 《Journal of Solid State Electrochemistry》2010,14(2):169-174
Polyaniline–tin dioxide (PANI-SnO2) composites were prepared by chemical polymerization method, and characterized by scanning electron microscopy, transmission
electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. Due to the good stability in diluted
acidic solution, PANI-SnO2 composites were selected as the catalyst support and second catalyst for methanol electro-oxidation. The electrocatalytic
properties of the PANI-SnO2 supported Pt catalyst (Pt/PANI-SnO2) for methanol oxidation have been investigated by cyclic voltammetry, chronoamperometry, and chronopotentiometry. Under the
same loading mass of Pt, the Pt/PANI-SnO2 catalyst shows higher electrocatalytic activity towards methanol electro-oxidation than Pt/SnO2 catalyst. 相似文献
20.
T. V. Belysheva E. Yu. Spiridonova V. F. Gromov G. N. Gerasimov L. I. Trakhtenberg 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(12):2116-2121
The sensor properties of In2O3 · SnO2 polycrystalline films having different compositions were studied in the detection of 2% hydrogen in air over the temperature
range 330–530°C. Films containing 19% In2O3 were most sensitive to hydrogen. The temperature dependence of the sensitivity of sensors passed a maximum, the position
of which depended on the composition of the film. The temperature at which sensor sensitivity was maximum decreased as the
content of indium oxide increased. This temperature was 485°C for the SnO2 film and 425°C for the In2O3 film. The response and relaxation times of sensors also decreased as the amount of In2O3 in the composite metal oxide film increased. Possible mechanisms of the sensor sensitivity of the films are discussed. 相似文献