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1.
A series of Lil-xNaxV3O8 materials was prepared by solution reaction followed by calcination method and their electrochemical performances in 2 M LieSOa-water-ethanol solution as negative electrodes for aqueous electrolyte lithium ion battery were studied and compared each other. X-ray diffraction analysis revealed that partially substituting sodium for lithium in LiV3Os could increase the interlayer distances of （100） plane. Cyclic voltammetric experiments have demonstrated that the Li^＋ insertion and extraction kinetics of Li0.7Na0.3V3O8 is superior to that of LiV3O8. Charge/discharge results showed that the discharge specific capacity of Li0.7Na0.3V3O8 electrode is higher than that of LiV3O8 electrode. 相似文献
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《浙江大学学报(A卷英文版)》2021,(2)
Pyrolysis is a cost-effective and safe method for the disposal of radioactive spent resins. In this work, the catalytic effects of V_2O_5 on the pyrolysis of cation exchange resin are investigated for the first time. The results show that it is a better catalyst than others so far studied and achieves a lowering of final pyrolysis temperature and residual rate simultaneously when aided by physical blending. The maximum reductions of the final pyrolysis temperature and the residual rate are 173 ℃ and 11.9%(in weight), respectively. Under the action of V_2O_5, low-temperature(445℃) removal of partial sulfonic acid groups occurs and the pyrolysis of the resin copolymer matrix is promoted. This is demonstrated by the analysis of pyrolysis residues at different temperatures by X-ray photoelectron spectroscopy(XPS) and element analysis. The catalytic activity of V_2O_5 is determined by effects both at acid sites and oxidation-reduction centers via H_2-TPR(temperature programmed reduction), O_2-TPD(temperature programmed desorption), CO_2-TPD, and NH_3-TPD. The catalytic effect of oxidation-reduction centers in V_2O_5 is achieved by close contact with the sulfur bond through chemisorption under the effect of acid sites. V_2O_5 is also believed to be the reason for the removal of partial sulfonic acid groups at lower temperatures(445℃). V_2O_5 is an effective catalyst for spent resin pyrolysis and can be further applied in industry. 相似文献
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The Mg-based hydrogen storage alloys Mg2Ni, Mg2Ni0.7Fe0.3 and Mgl.7Alo.3Ni were successfully synthesized by a two-step process （sintering and ball milling）. The crystal structure and microstructure were examined by X-ray diffraction, Scanning Electron Microscope and Malvern particle size analyzer. New phase appears in the tripe alloys doped with A1 and Fe, and the particle size ranges from 3μm to 5 μm. The electrochemical performance studies indicate that the partial substitution of AI for Mg, and Fe for Ni significantly improve the cycle life, reversibility of hydrogen absorption and desorption. The diffusion process is the control step in the electrode reaction of hydrogen storage alloys. 相似文献
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Ml0.7Mm0.3Ni3.7Co0.7Mn0.4Al0.2 nanocrystalline hydrogen storage materials are prepared by melt-spinning(MS).X-ray diffraction is used for the measurement of the nanocrystalline size.Compared to the electrode of polycrystalline alloys,the property of activation MH9metal hydride)electrode of the alloys with nanometer scale became worse and the inital discharge capacity decreased.It may be ascribed to the decrease of the total amount of rare earth metals and the increase of oxygen on the surface from the analysis of components of the alloys.After heat-treatment,the electrochemical performance of MH electrode of as-spun alloys could be improved,which could be attributed to the alleviation of the lattice strain. 相似文献
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We previously reported the direct electrochemical detection of insulin at bare carbon electrodes. Here a novel modified acetylene carbon black paste electrode(SiC/CB-CPE), based on the outstanding characteristics of silicon carbide nanostructure,was developed for the electrooxidation of insulin in alkaline solution and it was characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) in 5 mmol/L Fe(CN)63-/4- solution. It is found that silicon carbide nanostructure doped into the CB-CPE greatly facilitates the redox electrochemistry of Fe(CN)63-/4- probe and the electrochemical oxidation of insulin. The electrooxidation of insulin is a one-electron and one-proton reaction and an irreversible adsorption-controlled electrode process. The anodic oxidation current increases linearly with the concentration of insulin from 1×10-7mol/L to1.2×10-6mol/L in 0.1 mol/L Na2CO3-NaHCO3 buffer solution(pH 10.0) and the detection limit was 50 nmol/L. In addition, the SiC/CB-CPE shows good sensitivity, reproducibility, renewability and capacity of resisting disturbance. 相似文献
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A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain p H value was limited and hardly related to F-concentration and boric acid. It is better to control p H value below 11.5 and the aluminum concentration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80 ℃ for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method. 相似文献
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The photo-corrosion of electrodeposited polycrystalline CdSe electrode was inhibited effectively by coating a thin layer of the conductive polyaniline (PAN) film. The relation between the performance and internal band structure of such film-covered PAN/CdSe electrode was studied by the electrochemical modulation reflectance spectrum (EMRS). EMRS of beth CdSe and PAN/CdSe electrodes in K4Fe(CN)6/K3Fe(CN)6 solution exhibited typical France-Keidysh oscillations, by which the values of the energy gap and flat band potential were determined. The EMRS results indicated that the energy band structure of CdSe electrode was not changed after coated with PAN film, so that the photoelectrochemical characteristic of PAN/CdSe electrode was rather similar to that of CdSe electrode. 相似文献
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Global asymptotic stability of positive equilibrium in a 3-species cooperating model with time delay
WANG Chang-you 《重庆大学学报(英文版)》2007,6(3):192-199
The asymptotic behavior of the time-dependent solution for a 3-species cooperating model was investigated with the effects of both diffusion and time delay taken into consideration. We proved the global asymptotic stability of a positive steady-state solution to the model problem by using coupled upper and lower solutions for a more general reaction-diffusion system that gives a common framework for 3-species cooperating model problems. The result of global asymptotic stability implies that the model system coexistence is permanent. Some global asymptotic stability results for 2-species cooperating reaction-diffusion systems are included in the discussion, and some known results are extended. 相似文献
9.
Ying YE Xia HUANG Yi-wen PAN Zhen-hua HAN Wei ZHAO 《浙江大学学报(A卷英文版)》2008,9(3):423-428
The preparation approach and calibration result of an improved type of ion selective electrode （ISE）, which is used to measure the total dissolved S^2-, are introduced in this paper. The improved Ag/Ag2S electrode uses silver wire as the substrate, which is surrounded by electric polymer containing superfine silver powder. After the stabilization of the epoxy-resin, Ag2S layer was formed by chemical reaction with 0.2 mol/L （NH4）2S solution for 5 min. With Ag/AgC1 as reference electrode, the Ag/Ag2S electrode can be used to measure dissolved S^2-. The correlation between the measured potentials and the logarithm of dissolved S^2- is found to be linear, within range of the concentration of dissolved S^2- from 10^-2-10-7 mol/L. The slope of the regression line between measured potential and logarithm of dissolved S^2- is about -27.7, which agrees well with the theoretical Nernst value -29.6. Furthermore, the performance of the improved Ag/Ag2S electrode, such as the response time, sensitivity and stability, greatly outweighs the conventional Ag/Ag2S electrode. 相似文献
10.
Existing methods for synthesizing p-benzoquinone have drawbacks with respect to environmental protection, production scale, or industrial value. Therefore, it is imperative that a simple and environmentally friendly alternative be developed. The approach that involves preparing p-benzoquinone by the catalytic oxidation of benzene with hydrogen peroxide(H_2O_2) over copper-modified titanium silicalite-1(Cu/TS-1) has a certain superiority due to its green synthesis and mild reaction conditions. In this study, Cu/TS-1 catalyst was prepared by the wet impregnation of TS-1 with an aqueous solution of Cu(NO_3)_2 and then characterized by X-ray diffraction, Fourier transform infrared spectroscopy, diffuse reflectance UV–Vis spectroscopy, scanning electron microscopy, inductively coupled plasma mass spectrometry, X-ray fluorescence, and analysis of the N_2 adsorption–desorption isotherms. The results reveal that Cu species exist mainly in the form of amorphous Cu O that is well dispersed on the surface of catalysts, with no major change in the molecular sieve framework. After optimizing the reaction conditions, a desirable p-benzoquinone selectivity(88.4%) and benzene conversion(18.3%) were obtained when the doping of Cu in Cu/TS-1 is 1.95 wt%. In addition, Cu/TS-1 can be conveniently regenerated, showing a slight decrease in catalytic capability after initial use, which then stabilizes in subsequent circulations. The satisfactory stability and low cost of synthesizing Cu/TS-1 give this method considerable potential for further industrialization. 相似文献
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Facile Fabrication of Fe_3O_4@TiO_2@C Yolk–Shell Spheres as Anode Material for Lithium Ion Batteries
Transition metal oxides have been actively exploited for application in lithium ion batteries due to their facile synthesis,high specific capacity,and environmental-friendly.In this paper,Fe_3O_4@TiO_2@C yolk-shell(Y-S) spheres,used as anode material for lithium ion batteries,were successfully fabricated by Stober method.XRD patterns reveal that Fe_3O_4@TiO_2@C Y-S spheres possess a good crystallinity.But the diffraction peaks' intensity of Fe_3O_4 crystals in the composites is much weaker than that of bare Fe_3O_4 spheres,indicating that the outer anatase TiO_2@C layer can cover up the diffraction peaks of inner Fe_3O_4 spheres.The yolk-shell structure of Fe_3O_4@TiO_2@C spheres is further characterized by TEM,HAADFSTEM,and EDS mapping.The yolk-shell structure is good for improving the cycling stability of the inner Fe_3O_4 spheres during lithium ions insertion-extraction processes.When tested at 200 mA/g,the Fe_3O_4@TiO_2@C Y-S spheres can provide a stable discharge capacity of 450 mAh/g over 100 cycles,which is much better than that of bare Fe_3O_4 spheres and TiO_2@C spheres.Furthermore,cyclic voltammetry curves show that the composites have a good cycling stability compared to bare Fe_3O_4 spheres. 相似文献
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通过对化验室常用标准液稳定性较差的硫代硫酸钠标准溶液的分析,认为其标准液的有效期在2个月以内才能保证检验正常、检出的数据有效. 相似文献
15.
采取三种方法合成了镍钴酸锂电极材料Lia Ni0.7Co0.3O2,用电化学实验方法研究了合成方法对材料的电化学性能的影响,材料用XRD表征.结果表明:通过预处理后合成的电极材料具有较好的电化学性能,首次充放电比容量可达到196.5和167.9 mAh·g-1. 相似文献
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1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｉｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｍｅｔａｌｈｙｄｒｉｄｅｓａｒｅａｎｉｄｅａｌｍｅｄｉｕｍｆｏｒｈｙｄｒｏｇｅｎｓｔｏｒａｇｅｄｕｅｔｏｔｈｅｉｒｈｉｇｈｄｅｎｓｉｔｙａｎｄｈｉｇｈ ｐｕｒｉｔｙｏｆｈｙｄｒｏｇｅｎ .Ｈｏｗｅｖｅｒ ,ａｌｌｋｎｏｗｎｃｏｎｖｅｎｔｉｏｎａｌｍｅｔａｌｈｙｄｒｉｄｅｓ ,ｉｎｃｌｕｄｉｎｇｉｎｔｅｒｍｅｔａｌｌｉｃｃｏｍｐｏｕｎｄｓＡＢ5,ＡＢ2 ,ａｎｄＡＢ ,ｈａｖｅｒｅｖｅｒｓｉｂｌｅｇｒａｖｉ ｍｅｔｒｉｃＨ ｄｅｎｓｉｔｉｅｓｎｏｍｏ… 相似文献
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在合理选择化学Ni-P合金配方和工艺条件的前提下,采用对比试验比较了几种稳定剂对化学镀Ni-P合金性能的影响,综合各类稳定剂对镀液及镀层性能的影响,选取影响工艺性能的3个工艺参数,采取正交试验方案,研究了Na2S2O3与其他稳定剂复配时的性能变化规律,得出了较理想的稳定剂用量范围。 相似文献
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本文根据无水碳酸钠与水作用生成结晶水合物的原理,以及H_2O_2和H_2O分子的某些相似性,研究了Na_2CO_3—H_2O_2复合物的制备方法和作为鱼塘增氧剂的性质测定。 相似文献