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101.
J. L. Gautier E. Meza E. Silva C. Lamas C. Silva 《Journal of Solid State Electrochemistry》1997,1(2):126-133
The electrochemical insertion of lithium in the spinel-type manganite with the formula ZnNi
y
Mn2–
y
O4 has been studied. The galvanostatic discharge curves show that the best performance is obtained for y = 0.25, where a tetragonal to cubic structural transformation occurs. The thermodynamics and kinetics of the process of insertion
of the lithium into the tetragonal spinel Li
x
ZnNi0.25Mn1.75O4 (x = 0.05–1.3) have been studied. The molar thermodynamic quantities, such as enthalpy, entropy and free energy determined by
EMF-T measurements, varied with the lithium concentration in the oxide structure, and a major variation was observed around
x = 0.8. The chemical diffusion coefficient of lithium in these spinels was also determined. Structural analysis, degree of
oxidation and magnetic susceptibility measurements were carried out for the lithiated oxides in order to obtain the cationic
distribution as a function of x. It has been possible to demonstrate that, upon lithium insertion, Mn4+ ions on B sites are reduced to Mn3+ and then to Mn2+. A cooperative Jahn-Teller effect is present in these spinel manganese-nickel oxides.
Received: 4 February 1997 / Accepted: 11 April 1997 相似文献
102.
F. H. B. Lima M. L. Calegaro E. A. Ticianelli 《Russian Journal of Electrochemistry》2006,42(12):1283-1290
This work reviews the studies conducted in this laboratory of the oxygen reduction reaction (ORR) on electrocatalysts formed
by Pt-M/C (M = V, Cr, Co) and Ag-Pt/C alloys and on different Mn oxides (MnO/C, Mn3O4/C, MnO2/C) in KOH electrolyte. The physical and electronic properties of the materials are investigated by in situ XAS (x-ray absorption
spectroscopy) in the XANES (x-ray absorption near edge structure) region. The electrocatalytic activity for the ORR on the
different catalysts is compared through mass-transport-corrected Tafel plots. The XANES results for the Pt-M/C and Ag-Pt/C
composites at high electrode potentials show lower vacancy of the Pt 5d band compared to pure Pt/C, while for the results indicate a chance of the Mn oxidation state as a function of the electrode
potential. The electrochemical measurements evidence increased electrocatalytic activity of the Pt alloys compared to pure
Pt and this is attributed to a lowering of the adsorption strength of adsorbed oxygen species caused by the reduced Pt reactivity.
An activity enhancement of the Ag atoms on the Ag-Pt/C alloys compared to pure Ag is ascribed to an electronic effect induced
by the presence of Pt, increasing the Ag-O adsorption strength. In the case of the MnyOx/C materials, the electrochemical results show low activity for MnO/C and higher activity for MnO2/C and Mn3O4/C. This is explained based on the activation for the ORR, which is higher for the material with higher MnO2 contents and the occurrence of a mediation processes involving the reduction of Mn(IV) to Mn(III), followed by the electron
transfer of Mn(III) to oxygen.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 12, pp. 1417–1426.
Based on the report delivered at the 8th International Frumkin Symposium “Kinetics of the Electrode Processes,” October 18–22,
2005, Moscow.
The text was submitted by the authors in English. 相似文献
103.
A. M. Nazarov E. M. Chainikova R. L. Safiullin S. L. Khursan V. D. Komissarov 《Reaction Kinetics and Catalysis Letters》1997,61(1):173-174
The rate constants of benzophenone oxide decay measured at 25°C by flash photolysis (FPh) strongly depend on the nature of
the solvent [2k=(2.6±0.3)×107 L mol−1 s−1 in CH3CN, and (2.0±0.2)×109 L mol−1 s−1 in pentane]. 相似文献
104.
Hajime Kabashima Hideto Tsuji Hideshi Hattori 《Reaction Kinetics and Catalysis Letters》1996,58(2):255-259
All the alkaline earth oxides exhibit activities for double, bond isomerization of 5-vinylbicyclo[2.2.1]hept-2-ene (VBH) to 5-ethylidenebicyclo[2.2.1]hept-2-ene (EBH) at a reaction temperature of 273 K. The order of the activity on the basis of unit weight of catalyst was CaO>MgO>SrO>BaO when compared under optimum pretreatment conditions. The E/Z ratio in the products is determined by the reaction temperature regardless of the type of catalyst; the ratios were 82/18 and 88/12 for the reaction temperatures of 323 and 273 K, respectively. 相似文献
105.
Francisco Batista-Viera Mariela Barbieri Karen Ovsejevi Carmen Manta Jan Carlsson 《Applied biochemistry and biotechnology》1991,31(2):175-195
A new method for the reversible immobilization of thiol bimolecules, e.g., thiolpeptides and thiolproteins, to beaded agarose
and other solid phases is reported. The method consists of an activation and a coupling step. The activation is based on oxidation
of disulfides (or thiol groups via disulfides) present in a solid phase by hydrogen peroxide at moderately acidic pH. This
oxidation leads to disulfide oxides (thiolsulfinate groups of which the majority are further oxidized to thiolsulfonate).
The thiolsulfonate groups react easily with thiol compounds, which become immobilized via disulfide bonds. The pH range for
thiol coupling is wide (pH 5-8), but for most thiols the reaction seems to proceed faster at pH>7. The stability of the reactive
group to hydrolysis, especially at neutral and weakly acidic pH, is very high. The activated gel, therefore, can be stored
as a suspension at pH 5 for extended periods. The method has been used to reversibly immobilize glutathione, β-galactosidase,
alcohol dehydrogenase, urease, and papain, all with exposed thiol groups as well as thiolated bovine serum albumin and sweet-potato
β-amylase.
Depending on the thiol content of starting thiol-agarose, thiol-sulfonate-agarose derivatives with different binding capacities
can be obtained. Thus, up to 5.0 mg (16 μmol) glutathione and 15 mg thiol-protein/mL gel derivative have been immobilized. 相似文献
106.
John Bentley Dr. Salil Desai Dr. Bishnu Prasad Bastakoti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9241-9252
Tungsten oxide (WO3) has received ever more attention and has been highly researched over the last decade due to its being a low-cost transition metal semiconductor with tunable, yet widely stable, band gaps. This minireview briefly highlights the challenges in the design and synthesis of porous WO3 including methods, precursors, solvent effects, crystal phases, and surface activities of the porous WO3 base material. These topics are explored while also drawing a connection of how the morphology and crystal phase affect the band gap. The shifts in band gap not only impact the optical properties of tungsten but also allow tuning to operate on different energy levels, which makes WO3 highly desirable in many applications such as supercapacitors, batteries, solar cells, catalysts, sensors, smart windows, and bioapplications. 相似文献
107.
108.
《Progress in Solid State Chemistry》2014,42(3):23-36
The series of compounds in the BaLn2O4 family (Ln = La–Lu, Y) has been synthesized for the first time in single crystalline form, using a molten metal flux. The series crystallizes in the CaV2O4 structure type with primitive orthorhombic symmetry (space group Pnma, #62), and a complete structural study of atomic positions, bonds, angles, and distortions across the lanthanide series is presented. With the exception of the Y, La, Eu, and Lu members, magnetic susceptibility measurements were performed between 2 K and 300 K. BaCe2O4 and BaYb2O4 display large crystal fields effects and suppression of magnetic ordering. All compounds show signs of magnetic frustration due to the trigonal arrangements of the trivalent lanthanide cations in the structure. 相似文献
109.
Yu-Liang Lin Yu-Hsuan Tseng Jhih-Hao Ho Yi-Fan Chen Prof. Jiun-Tai Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(60):14981-14988
Composite polymer electrolytes (CPEs) with smart, stimuli-responsive characteristics have gained considerable attention owing to their noninvasive manipulation and applications in future technologies. To address this potential, in this work, we demonstrate photoresponsive composite polymer electrolytes, consisting of gel polymer electrolyte (GPE) and spiropyran-immobilized nanoporous anodic aluminum oxide (SP-AAO) templates. Under UV irradiation, the close SP form isomerizes to the open merocyanine (MC) form, creating extremely polarized AAO surfaces; whereas, under visible light irradiation, the MC form reverts to the SP form, creating neutral surface conditions. The electrostatic interactions between ions and AAO surfaces are investigated by attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. Moreover, the behavior of ionic conductivity of the GPE@SP-AAO is found to be consistent with the kinetics of isomerization tracked by UV-Vis spectroscopy. This work provides a promising platform for developing next-generation photoelectronic smart devices. 相似文献
110.