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1.
The direct electrochemical reduction of hemin, protoporphyrin(IX) iron(III) chloride, ligated with strong or weak heterocyclic bases, was investigated in the ionic liquids (IL), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF6]), using cyclic voltammetry and chronocoulometry. Hemin complexed with N-methylimidazole (NMI) or with pyridine had E1/2 values slightly (4–59 mV) more positive in IL (without electrolyte) than in methanol (1.0 M electrolyte) using a gold electrode. NMI-ligated hemin had a lower E1/2 than pyridine-ligated hemin in either IL, consistent with the stronger electron donor characteristic of NMI. [Bmim][PF6] solutions consistently yielded E1/2 values 30 mV more negative than [omim][PF6] solutions. The diffusion coefficients Do of hemin in the IL ranged between 1.50 and 2.80×10−7 cm2 s−1, while the heterogeneous electron-transfer rate constants ks ranged between 3.7 and 14.3×10−3 cm s−1. Cyclic voltammetry of hemin adsorbed to a gold surface through 4,4′-bispyridyl disulfide (AT4) linkages showed a large positive shift in the oxidation wave, indicating that adsorption stabilizes the reduced hemin state. The surface concentration Γo of the adsorbed hemin was determined to be 1.21×10−10 mol cm−2, indicating the presence of one or more complete monolayers of hemin. These findings suggest that while hemin is electrochemically active in IL, its behavior is modified by the ligand field strength and surface adsorption phenomena. 相似文献
2.
A study on the liquid–liquid equilibria of 1-alkyl-3-methylimidazolium hexafluorophosphate with ethanol and alkanes 总被引:1,自引:0,他引:1
This work demonstrates the ability of the 1-alkyl-3-methylimidazolium hexafluorophosphate to act as an extraction solvent in petrochemical processes for the removal of alkanes from their azeotropic mixture with ethanol. LLE (liquid–liquid equilibrium) of the ternary systems hexane + ethanol + 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIM PF6) or 1-octyl-3-methylimidazolium hexafluorophosphate (OMIM PF6) and heptane + ethanol + OMIM PF6 are carried out at 298.15 K and atmospheric pressure. Experimental liquid–liquid data are correlated by using different equations. The solute distribution ratio and the selectivity, determined from tie-line data, suggest the efficiency of the ILs used as solvents. A comparison with other IL, in terms of solvent capacity, is included. The liquid–liquid extraction process is simulated by using conventional software and the obtained results are shown. 相似文献
3.
R. Chandrasekaran Y. Soneda J. Yamashita M. Kodama H. Hatori 《Journal of Solid State Electrochemistry》2008,12(10):1349-1355
The effect of polymer–salt addition in the activated carbon electrode for electric double-layer capacitor (EDLC) has been
investigated. A series of composite thin film electrode consisting of activated carbon, carbon black, polytetrafluoroethylene
and polymer–salt complex (polyethyleneoxide–LiClO4) with an appropriate weight ratio were prepared and examined their performance for EDLCs using 1 mol L−1 LiClO4 in ethylene carbonate:diethylcarbonate electrolyte solution. The electrochemical capacitance performances of these electrodes
with different compositions were characterized by cyclic voltammetry, galvanostatic charge–discharge cycling, and AC impedance
measurements. By comparison, the best results were obtained with a composite electrode rich in polymer–salt additive (132 F
g−1 at 100 mA g−1 of galvanostatic experiment). In general, the polymer–salt-containing electrode had shown improved performance over activated
carbon electrodes without polymer–salt at high current density. 相似文献
4.
Yafen Zhang Rui Yan Faqiong Zhao Baizhao Zeng 《Colloids and surfaces. B, Biointerfaces》2009,71(2):288-292
The direct electron transfer and electrocatalysis of hemoglobin (Hb) entrapped in polyvinyl alcohol (PVA)–room temperature ionic liquid (i.e., 1-octyl-3-methylimidazolium hexafluorophosphate [OMIM]PF6) composition has been investigated by using cyclic voltammetry and chronocoulometry. It is found that the composition can promote the direct electron transfer of Hb and the heterogeneous electron transfer rate constant (ks) of immobilized Hb is enhanced to 19.9 s−1. The immobilized Hb also shows high electro-catalytic activity towards the redox of oxygen, hydrogen peroxide and nitrite. The Michaelis constants (Km) decrease to 1.2 × 10−4 M (for hydrogen peroxide) and 9.4 × 10−3 M (for nitrite). The surface concentration of electroactive Hb is estimated and it is ca. 1.4 × 10−10 mol cm−2, meaning that several layers of immobilized Hb take part in the electrochemical reaction. When gold nanoparticles (GNP) is introduced into the composition, the resulting PVA–GNP–[OMIM]PF6 composition presents better performance. The electrochemical characteristic of immobilized Hb is improved further. Thus PVA–GNP–[OMIM]PF6 composition is more suitable for the immobilization of Hb. Therefore, it is a good strategy to prepare novel composition for protein immobilization by using several materials with different function. 相似文献
5.
Possible use of room temperature ionic liquids (RTILs) as chelate extraction solvent was evaluated by using 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF6]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF6]). These RTILs showed high extraction performance for divalent metal cations with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (Htta). The extracted metals were back-extracted into 1 mol dm−3 nitric acid quantitatively. Furthermore, the extracted species were estimated as neutral hydrated complexes M(tta)2(H2O)n (n= 1 or 2) for M = Ni, Cu and Pb and anionic complexes M(tta)3− for M = Mn, Co, Zn and Cd. 相似文献
6.
离子液体型表面活性剂研究 总被引:2,自引:0,他引:2
以1-甲基咪唑为原料, 制备了6个常规离子液体: 1-正丁基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[bmim][BF4]及[bmim][PF6])、1-正己基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[hmim][BF4]及[hmim][PF6])、1-正十六烷基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[C16mim][BF4]及[C16mim][PF6])和4个功能化离子液体: 1-(2-羟乙基)-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[2-hemim][BF4]及[2-hemim][PF6])、1-乙氧羰基甲基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[eocmmim][BF4]及[eocmmim][PF6]). 研究了这两类离子液体的一些物理性能, 旨在挖掘离子液体在香料香精化妆品工业中的应用价值. 分别检测了它们与一般溶剂的互溶性, 并测定了它们的表面张力和发泡性能, 实验结果表明, 仅[C16mim][BF4]和[C16mim][PF6]具有发泡性能, 发泡力分别为68和120 mm. 相似文献
7.
Changzhou Yuan Long Yang Linrui Hou Diankai Li Laifa Shen Fang Zhang Xiaogang Zhang 《Journal of Solid State Electrochemistry》2012,16(4):1519-1525
A facile hydrothermal strategy was first proposed to synthesize flower-like Co(OH)2 hierarchical microspheres. Further physical characterizations revealed that the flower-like Co(OH)2 microspherical superstructures were self-assembled by one-dimension nanobelts with rich mesopores. Electrochemical performance
of the flower-like Co(OH)2 hierarchical superstructures were investigated by cyclic voltammgoram, galvanostatic charge–discharge and electrochemical
impedance spectroscopy in 3 M KOH aqueous electrolyte. Electrochemical data indicated that the flower-like Co(OH)2 superstructures delivered a specific capacitance of 434 F g−1 at 10 mA cm−2 (about 1.33 A g−1), and even kept it as high as 365 F g−1 at about 5.33 A g−1. Furthermore, the SC degradation of about 8% after 1,500 continuous charge–discharge cycles at 5.33 A g−1 demonstrates their good electrochemical stability at large current densities. 相似文献
8.
Densities and viscosities were determined for binary mixtures of 2,2,2-trifluoroethanol (TFE) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) or 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([bmim][NTf2]) over the entire range of composition. The experimental measurements were carried out at temperatures ranging from 278.15 K to 333.15 K, at atmospheric pressure. The densities and viscosities of the pure ionic liquids and their mixtures with TFE were described successfully by an empirical third-order polynomial and by the Vogel–Fulcher–Tammann equation, respectively. In addition, excess molar volumes and viscosity deviations were determined from densities and viscosities of mixtures, respectively, and fitted by using the Redlich–Kister equation. 相似文献
9.
Preparation and electrochemical properties of nanofiber poly(2,5-dihydroxyaniline)/activated carbon composite electrode for supercapacitor 总被引:1,自引:0,他引:1
Lan Liu Wei Wang Wu-yuan Zou Ben-lin He Ming-liang Sun Min Wang Xue-fei Xu 《Journal of Solid State Electrochemistry》2010,14(12):2219-2224
In this study, poly(2,5-dihydroxyaniline) (PDHA) was successfully prepared by electrochemical method on the surface of active
carbon (AC) electrodes. The physical and electrochemistry properties of PDHA/AC composite electrode compared with pure AC
electrode were investigated by scanning electronic microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy,
cycle life test. From SEM, PDHA presents nanofiber network morphology. The diameter of the nanofiber PDHA is about 200–300 nm.
PDHA/AC composite electrode shows redox peaks in CV curve and voltage plateaus in galvanostatic charge–discharge curve, and
all these indicate that PDHA/AC composite electrode has more advantages. The maintenance of the capacitance compared to initial
cycle capacitance of composite electrode is about 90% during the charge–discharge cycles. In conclusion, The PDHA/AC composite
electrode shows much higher specific capacitance (958 F g−1), better power characteristics, longer cycle life. Therefore, PDHA/AC composite electrodes were more promising for application
in capacitor. This can be attributed to the introduction of nanofiber PDHA. The effect and role of PDHA in the composite electrodes
were also discussed in detail. 相似文献
10.
Activated aryl halides undergo smooth nucleophilic substitution reactions with secondary amines in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) or 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) ionic liquids (ILs) at room temperature to afford the corresponding arylamines in excellent yields under mild and neutral conditions. 相似文献
11.
Epoxides undergo smooth ring-opening with aryl amines in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) or 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) ionic liquids under mild and neutral conditions to afford the corresponding β-amino alcohols in excellent yields with high regioselectivity. 相似文献
12.
Guocheng Xu Wei Wang Xiaofei Qu Yansheng Yin Lei Chu Benlin He Huikang Wu Jingrui Fang Yusheng Bao Liang Liang 《European Polymer Journal》2009,45(9):2701-2707
Polyaniline was deposited potentiodynamically on a stainless steel substrate in the presence of an inorganic acids (sulfuric acid). The electrochemical characterization of the electrode was carried out by means of cyclic voltammetry and electrochemical impedance spectroscopy in the organic acids (p-toluene sulfonic acid) solution. The results show that polyaniline has a high specific capacitance of 431.8 F g−1 at 1 mV s−1, high coulombic efficiency of 95.6% at 20 mV s−1, and exhibits a high reversibility. This indicates the promising feasibility of the polyaniline used as an electrochemical capacitor material in the electrolyte of p-toluene sulfonic acid solution especially at high charge–discharge process. 相似文献
13.
Electrochemical capacitance of nickel oxide nanotubes synthesized in anodic aluminum oxide templates
Juan Xu Lan Gao Jianyu Cao Wenchang Wang Zhidong Chen 《Journal of Solid State Electrochemistry》2011,15(9):2005-2011
Nickel oxide (NiO) nanotubes for supercapacitors were synthesized by chemically depositing nickel hydroxide in anodic aluminum
oxide templates and thermally annealing at 360 °C. The synthesized nanotubes have been characterized by scanning electron
microscopy, transmission electron microscopy, and X-ray diffraction. The capacitive behavior of the NiO nanotubes was investigated
by cyclic voltammetry, galvanostatic charge–discharge experiment, and electrochemical impedance spectroscopy in 6 M KOH. The
electrochemical data demonstrate that the NiO nanotubes display good capacitive behavior with a specific capacitance of 266 F g−1 at a current density of 0.1 A g−1 and excellent specific capacitance retention of ca. 93% after 1,000 continuous charge–discharge cycles, indicating that the
NiO nanotubes can become promising electroactive materials for supercapacitor. 相似文献
14.
《Fluid Phase Equilibria》2006,248(2):211-216
UV–vis spectroscopy and conductivity measurement techniques were used to study the physicochemical and structural properties of the binary or ternary mixtures of 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) + organic solvent and 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) + organic solvent systems. The solvents involved were acetonitrile, water, ethanol, ethyl acetate, and tetrahydrofuran. It was indicated that the micropolarity and the aggregation behavior of the mixtures depend strongly on the dielectric constants of the solvents and the composition of the mixtures. 相似文献
15.
Jing-Jing Deng Jian-Cheng Deng Zi-Ling Liu Hui-Ren Deng Bo Liu 《Journal of Solid State Electrochemistry》2009,13(9):1387-1394
Ni–Co oxide nanocomposite was prepared by thermal decomposition of the precursor obtained via a new method—coordination homogeneous
coprecipitation method. The synthesized sample was characterized physically by X-ray diffraction, scanning electron microcopy,
energy dispersive spectrum, transmission electron microscope, and Brunauer–Emmett–Teller surface area measurement, respectively.
Electrochemical characterization of Ni–Co oxide electrode was examined by cyclic voltammetry, galvanostatic charge–discharge,
and electrochemical impedance measurements in 6-mol L−1 KOH aqueous solution electrolyte. The results indicated that the addition of cobalt oxide not only changed the morphology
of NiO but also enhance its electrochemical capacitance value. A specific capacitance value of 306 F g−1 of Ni–Co oxide nanocomposite with n
Co = 0.5 (n
Co is the mole fraction of Co with respect to the sum of Co and Ni) was measured at the current density of 0.2 A g−1, nearly 1.5 times greater than that of pure NiO electrode. Lower resistance and better rate capability can also be observed. 相似文献
16.
A. M. Shestopalov S. G. Zlotin A. A. Shestopalov V. Yu. Mortikov L. A. Rodinovskaya 《Russian Chemical Bulletin》2004,53(3):573-579
The three-component reaction of 4-hydroxy-6-methylpyran-2(2H)-one with cyanoacetic acid derivatives and carbonyl compounds in EtOH or in the ionic liquid, viz., 1-butyl-3-methylimidazolinium hexafluorophosphate ([bmim][PF6]), affords substituted 2-amino-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyrans. The yield of substituted pyrano[4,3-b]pyrans in [bmim][PF6] is by 10—14% higher than that in EtOH. 相似文献
17.
The effect of the polyaniline morphology on the performance of polyaniline supercapacitors 总被引:1,自引:0,他引:1
Haihui Zhou Hong Chen Shenglian Luo Gewu Lu Wanzhi Wei Yafei Kuang 《Journal of Solid State Electrochemistry》2005,9(8):574-580
The polyaniline (PANI) prepared by the pulse galvanostatic method (PGM) or the galvanostatic method on a stainless steel substrate from an aqueous solution of 0.5 mol/l H2SO4 with 0.2 mol/l aniline has been studied as an electroactive material in supercapacitors. The electrochemical performance of the PANI supercapacitor is characterized by cyclic voltammetry, a galvanostatic charge–discharge test and electrochemical impedance spectroscopy in NaClO4 and HClO4 mixed electrolyte. The results show that PANI films with different morphology and hence different capacitance are synthesized by controlling the synthesis methods and conditions. Owing to the double-layer capacitance and pseudocapacitance increase with increasing real surface area of PANI, the capacitive performances of PANI were enhanced with increasing real surface area of PANI. The highest capacitance is obtained for the PANI film with nanofibrous morphology. From charge–discharge studies of a nanofibrous PANI capacitor, a specific capacitance of 609 F/g and a specific energy density of 26.8 Wh/kg have been obtained at a discharge current density of 1.5 mA/cm2. The PANI capacitor also shows little degradation of capacitance after 1,000 cycles. The effects of discharge current density and deposited charge of PANI on capacitance are investigated. The results indicate that the nanofibrous PANI prepared by the PGM is promising for supercapacitors. 相似文献
18.
Xingyan Wang Li Liu Xianyou Wang Li Bai Hao Wu Xiaoyan Zhang Lanhua Yi Quanqi Chen 《Journal of Solid State Electrochemistry》2011,15(4):643-648
Carbon aerogel (CA) microspheres were successfully synthesized by an inverse emulsion polymerization routine. Morphology and
physical properties of the CA microspheres were characterized by scanning electron microscopy, N2 sorption isotherm, and transmission electron microscopy. The results showed that the CA microspheres were all fine spheres
with diameters about 4 μm, and the CA microsphere was a typical mesoporous material with ordered mesoporous nano-network structure.
The maximum capacitance of the electrode obtained from cyclic voltammetry was 187.08 F/g and the capacitance of the supercapacitor
resulted from galvanostatic charge–discharge tests was up to 45.98 F/g. The supercapacitor using CA microsphere as electrode
material presented a long cycle life, high charge–discharge efficiency, and low R
s of 0.70 Ω in 6 M KOH electrolyte. 相似文献
19.
G. V. Kryshtal G. M. Zhdankina I. V. Astakhova S. G. Zlotin 《Russian Chemical Bulletin》2004,53(3):647-651
Metal carbonate-catalyzed reactions of CH-acids (diethyl malonate, ethyl acetoacetate, ethyl cyanoacetate, and ethyl 2-acetyl- and 2-ethoxycarbonyl-5,9-dimethyldeca-4,8-dienoates) with ,-unsaturated aldehydes (acrolein, crotonaldehyde, citral) were studied in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], and in a 1-butyl-3-methylimidazolium bromide ([bmim][Br]) — benzene system. The reactions with acrolein and crotonaldehyde afforded Michael addition products, those with citral resulted in Knoevenagel addition products. Sonication increased the yields of the Michael adducts. The ionic liquid [bmim][PF6] can be recovered and repeatedly used in the reactions. 相似文献
20.
Zhang Fang Jiang Jianwei Yuan Changzhou Hao Liang Shen Laifa Zhang Luojiang Zhang Xiaogang 《Journal of Solid State Electrochemistry》2012,16(5):1933-1940
Nanostructured Co
x
Ni1−x
–Al layered triple hydroxides (Co
x
Ni1−x
–Al LTHs) have been successfully synthesized by a facile hydrothermal method using glycine as chelating agent. The samples
were characterized by X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy and scanning electron microscopy.
The morphologies of Co
x
Ni1−x
–Al LTHs varied with the Co content and its effect on the electrochemical behavior was studied by cyclic voltammetry and galvanostatic
charge–discharge techniques. Electrochemical data demonstrated that the Co
x
Ni1−x
–Al LTHs with Co/Ni molar ratio of 3:2 owned the best performance and delivered a maximum specific capacitance of 1,375 F g−1 at a current density of 0.5 A g−1 and a good high-rate capability. The capacitance retained 93.3% of the initial value after 1,000 continuous charge–discharge
cycles at a current density of 2 A g−1. 相似文献