The article presents the findings of microscopic and electrochemical studies of electrooxidation of bismuth particle of varying sizes. Bismuth particles were immobilized on the surface of indifferent carbon containing screen-printed electrodes. The calculations and experimental studies demonstrated that the transition from macroparticles to nanoparticles caused a shift of the maximum current potential of bismuth oxidation into the area with more negative potentials. A positive correlation between experimental and calculated data confirms once again a relevant application of the earlier proposed mathematical model and the possible use of the shift of the maximum current potential of electrooxidation to describe electrochemical activity and energy properties of metal nanoparticles. 相似文献
The electric and electrochemical characteristics of cathodes made of La0.6Sr0.4Fe0.8Co0.2O3?δ (LSFC) and intended for fuel cells with electrolytes based on ceric oxide are studied. Adding cupric oxide into the LSFC cathode is shown to exert a favorable effect of the properties of the LSFC-CuO/SDC electrode system, where SDC stands for the CeO2-Sm2O3 electrolyte. The effect produced by cupric oxide when added in the form of nanopowder is perceptibly greater than in the case of micropowdered CuO. Adding a mere 0.5 wt % of nanopowdered CuO reduces the LSFC cathode resistance nearly tenfold. The cathode’s adhesion to the electrolyte substantially improves as well, which makes it possible to lower the cathode’s firing temperature by 100°C. The maximum of electrochemical activity is intrinsic to cathodes containing 2 wt % CuO, with the caking temperature of 1000°C. According to a 2011-h life test of the LSFC-SDC composite cathodes containing nanopowdered CuO, temporal stability of their electrochemical characteristics improves with the SDC content. The time dependences of the polarization resistance of cathodes containing 40–50 wt % SDC look like decaying exponential curves. The steady-state polarization resistance, calculated on the basis of this, is equal to 0.1–0.2 ohm cm2. At an overvoltage of less than 100 mV, the cathodes may provide for a current density of 0.5–1.0 A cm?2. 相似文献
The article presents the findings of microscopic and electrochemical studies of size-dependent gold particles electrooxidation.
Gold particles were immobilized on the surface of carbon-containing screen-printed electrodes. The experiment demonstrated
that the transition from macroparticles to nanoparticles caused a shift of the maximum current potential of gold oxidation
into the area with more negative potentials. A decrease in particle size resulted in an increase in the electrochemical activity
of metal. A positive correlation between experimental and calculated curves confirms a mathematical model (2) and correctness of the calculations. Measured parameters of voltammograms, in particular, maximum current potential, can
be used to describe the electrochemical activity and energy properties of nanoparticles. 相似文献
It is shown on the basis of a study of the IR spectra of indazoles, pyrazolopyridines, and pyrazolopyrazine in the solid state and of their N-deutero-substituted derivatives and hydrochlorides at room temperature and at the temperature of liquid nitrogen that these heterocycles exist in a tautomeric form in which the labile hydrogen atom is localized on the nitrogen atom of the pyrazole ring. It was established that 6-aminopyrazolopyridine exists in the crystalline state in the amino form and that it is protonated at the ring nitrogen atom rather than at the amino group. The applicability of the temperature-shift method for the detection not only of NH bands but also of ND bands is demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 662–667, May, 1977. 相似文献
The article presents the findings of microscopic and electrochemical studies of electrooxidation of bismuth particle of varying sizes. Bismuth particles were immobilized on the surface of indifferent carbon containing screen-printed electrodes. The calculations and experimental studies demonstrated that the transition from macroparticles to nanoparticles caused a shift of the maximum current potential of bismuth oxidation into the area with more negative potentials. A positive correlation between experimental and calculated data confirms once again a relevant application of the earlier proposed mathematical model and the possible use of the shift of the maximum current potential of electrooxidation to describe electrochemical activity and energy properties of metal nanoparticles.
The assignment of the frequency of the out-of-plane deformation vibration of pyrazole on the basis of an investigation of the temperature dependence of the IR spectrum is reexamined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1388–1389, October, 1974. 相似文献
The adsorption of block PS on the surface of spherical, round, and flaky particles of highly dispersed Zn powders with dimensions
of 3.5–23 μm and the interaction of the polymer with the surface of Zn powders in the composite films are studied by refractometry
and isothermal calorimetry. During establishment of adsorption equilibrium, the concentration of PS in the bulk of solution
increases, while, near the surface of Zn particles, the concentration of PS decreases, thus indicating the predominance of
absorption from solution of the solvent o-xylene. With the use of the thermodynamic cycle, including processes of solution of the polymer and Zn-PS film composite
and wetting of the Zn powder, the enthalpies of formation of PS-Zn composites are estimated. The enthalpies of mixing of filled
compositions comprise two contributions of opposite signs: In the low-filling region, the negative contribution of adhesion
interactions prevails, while in the region of high-filled compositions, a positive structural contribution, which is associated
with additional loosening of the glassy packing of PS near the filler surface, plays the decisive role. The contribution of
adhesion interaction is largely determined by the dimensions of filler particles, while the structural contribution is controlled
by their shape. The experimental evidence suggests that spherical particles possess the highest thermodynamic compatibility
with the polymer matrix of the composite material. 相似文献
This article presents the findings of microscopic and electrochemical studies of electrooxidation of silver nanoparticles of varying sizes in comparison with “bulk” silver. Silver particles were immobilized on the surface of indifferent carbon-containing screen-printed electrodes. Vacuum-deposited silver represented the “bulk” electrode. The calculations and experimental studies demonstrated that the transition from macro- to nanostructural electrodes is followed by a shift of the maximum current potential of metal oxidation into the area with more negative potentials. A positive correlation between experimental and calculated data confirms once again a relevant application of the earlier proposed mathematical model and the possible use of the shift of the maximum current potential of electrooxidation to describe the electrochemical activity and surface energy properties of metal nanoparticles. 相似文献
The results of the experiments on the destruction of micron-diameter conductors by an electromagnetic pulse, which is generated
in an inhomogeneous coaxial line by a high-voltage power source and has a subnanosecond front, are reported. The role of electrodynamic
processes in the surface layer of microconductors and in environment in the formation of the spatial structure of the plasma
channel and in the transformation of the energy of the source to the energy of radiation has been revealed. The spectral characteristics
of the radiation of the plasma channel have been analyzed. It has been shown that the radiation spectrum at the time of the
formation of the plasma corona is continuous. The most intense spectral lines of copper (510.554, 515.324, 521.82 nm) appear
at ∼3 ns after the formation of the plasma corona. The temperature has been estimated from the ratio of the intensities of
the spectral lines as Te ∼ 0.7 eV. 相似文献