共查询到20条相似文献,搜索用时 15 毫秒
1.
N. Borisenko E. Zschippang S. Zein El Abedin A. Bund F. Endres 《Electrochimica acta》2009,54(5):1519-5
The electroreduction of 0.5 M TaF5 on Au(1 1 1) and on polycrystalline gold substrates was investigated at room temperature in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py1,4]TFSA, by cyclic voltammetry, in situ scanning tunneling microscopy (STM) and electrochemical quartz crystal microbalance (EQCM). The electrochemical reduction of TaF5 in the employed ionic liquid occurs in several steps. The first redox process is attributed to the reduction of TaF5 to TaF3, which likely occurs in the solution, as EQCM indicates no mass change. The electrodeposition of tantalum occurs only in a very narrow potential window and is preceded by the formation of various non-stoichiometric tantalum subhalides. Attempts to deposit micrometer thick tantalum layers at room temperature fail, presumably because of kinetic reasons. 相似文献
2.
It has been established that the dependence of the E° values in function of the electrochemical media selected for a large amount of reversible redox probes in reduction and also in oxidation. For such a purpose several electroactive substances either in reduction (4-nitrotoluene, 1,3-dinitrobenzene, tetrakis(dimethylamino)ethylene, 1,3,5-trinitrobenzene, and 2,4,6-trinitroanisole) or oxidation (ferrocene, tetrathiofulvalene, tris-4-bromophenylamine, tris-4-tolylamine, and N,N,N′,N′-tetramethyl-para-phenylenediamine) have been studied in aprotic RTILs based on unsymmetrical organic cations (quaternary ammonium cations, such as 1-butyl-3-methyl imidazolium) and a weakly coordinating inorganic anion (anions with low Lewis basicities, e.g., BF4, PF6). Ion-pairing effects between imidazolium ions and anions and dianions for the electrochemically generated species, the solvation differences between BF4−/PF6− cations and dications as well as some different reaction mechanism pathways followed by these electrogenerated species in function of the solvent have also been carefully examined. 相似文献
3.
Electrochemical behaviour of Ti(IV) species in the ionic liquid (IL) 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BMMImBF4) was studied by means of chronopotentiometry (CP) and cyclic voltammetry (CV) in melts with different concentrations of TiF4 (2-35 mol%) within a temperature range of 65-180 °C. The electrochemical reduction of Ti(IV) was suggested to proceed via the sequence of one-electron steps with the formation of poorly soluble low valence intermediates (LVI). LVIs undergo further solid-state electrochemical reduction to Ti metal. Thin Ti coatings on a Pt substrate were thus obtained and characterized by ESEM method. FTIR spectroscopy was used for identification of the electrochemical active species of Ti(IV). The reaction 2BF4− + TiF4 ⇔ TiF62− + 2BF3↑ takes place in the concentrated solutions of TiF4 at elevated temperatures. 相似文献
4.
Electrochemical behaviour of titanium tetrachloride solutions in 1-butyl-2,3-dimethyl imidazolium azide (BMMImN3) at 65 °C has been examined. Ti(IV) reduction was studied with chronopotentiometry and cyclic voltammetry methods in melts with different concentrations of TiCl4. According to IR spectra, Ti(IV) exists in form of a hexaazidotitanate complex. The electrochemical reduction of this complex was found to proceed irreversibly to Ti(III) species only. Diffusion coefficients of Ti(IV) in this ionic liquid at temperature 65 °C were calculated based on the chronopotentiometry measurements at different TiCl4 concentrations (DTi(IV) = 1.3 ± 0.6 × 10−6 cm2 s−1). 相似文献
5.
Pierre ChamelotPatrice Palau Laurent MassotAndré Savall Pierre Taxil 《Electrochimica acta》2002,47(21):3423-3429
The influence of the molar ratio O-Ta noted Ro on the electrodeposition of tantalum in molten fluorides at 800 °C is examined. After additions of both K2TaF7 and Na2O, we observed: (i) tantalum deposit is obtained only by reduction of TaF72−; (ii) the oxide ions react with TaF72− to give oxifluoride species, identified first as TaOF52− and for higher oxide content, as TaO2F43−; (iii) the electroreduction of TaOF52− leads to the formation of an unstable bivalent tantalum species (TaO); (iv) the conversion of TaF72− to oxifluoride is complete when Ro is 1. Titration of Ta by ICP and oxygen by a carbothermal-reduction technique show that for Ro>1, insoluble compounds Na3TaO4 and NaTaO3 are formed. For Ro>3, these species seem to be solubilised. Electrodeposition runs on copper cathodes show that pure and coherent Ta coatings are obtained for a lower oxide content (Ro<0.5). For higher Ro, the faradic efficiencies are low. The coatings are powdery and include the presence of Na3TaO4, NaTaO3 and traces of Ta metal, arising from the decomposition of TaO. 相似文献
6.
Ki-Sub Kim 《Korean Journal of Chemical Engineering》2009,26(3):770-774
Two well known room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) and 1-butyl-3-methylimidazolium iodide ([BMIm][I]), were synthesized. Their physical properties such as reflective indices,
densities, viscosities, heat capacities, and heats of dilution were measured. The overall properties of [BMIm][BF4] obtained after two-step reactions were superior to those of the IL with a halide anion. The incorporation of lithium ions
using lithium tetrafluoroborate (LiBF4) in each IL was carried out and ionic conductivities as a function of temperature and Li ion concentration were investigated.
The isothermal conductivity graph showed a parabolic curve shape suggesting that the maximum values exist at a specific concentration
condition while they continuously increased as the temperature increased. The conductivities reached as high as 10−3 S·cm−1. 相似文献
7.
The ionic liquid l-butyl-3-methylimidazolium tetrafluoroborate is used as electrolyte in the electrochemical determination of the diffusion coefficient of ferrocene as a function of concentration by cyclic voltammetry and chronoamperometry. An improved synthesis of the room temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate is described, which yields a product of high purity suitable for electrochemical purposes. A qualitative color test is discussed which allows the simple detection of silver ion contaminations. The diffusion coefficient of ferrocene appears to be concentration dependent in the solvent chosen. 相似文献
8.
Vapor pressures were measured for acetonitrile+1-butyl-3-methylimidazolium chloride ([C4mim][Cl]),+1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and+1-hexyl-3-methylimidazolium chloride ([C6mim][Cl]) at temperatures of 313 to 353 K by a quasi-static method. The experimental data for the binary sys-tems were correlated by the non-random two liquid (NRTL) equation with an average absolute relative deviation (AARD) of within 1.84%. The results indicate that the three ionic liquids (ILs) can result in a negative deviation from the Raoult's law for the binary solutions containing acetonitrile, and the affinity between ILs and acetonitrile mole-cules fol ows the order [C4mim][BF4]+acetonitrile N [C4mim][Cl]+acetonitrile N [C6mim][Cl]+acetonitrile. 相似文献
9.
Vapor pressures were measured for acetonitrile+1-butyl-3-methylimidazolium chloride ([C4mim][Cl]),+1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and+1-hexyl-3-methylimidazolium chloride ... 相似文献
10.
Xiao-Ying Zhang Yi-Xin Hua Cun-Ying Xu Qi-Bo Zhang Xiao-Bo Cong Nan Xu 《Electrochimica acta》2011,56(24):8530
The direct electrochemical reduction of titanium dioxide (TiO2) to metallic titanium at room temperature is firstly studied in Lewis basic AlCl3–1-butyl-3-methylimidizolium (AlCl3–BMIC) ionic liquid. In this study, cyclic voltammetry, potentiodynamic polarization, sampled current voltammetry and X-ray photoelectron spectroscopy (XPS) techniques were utilized. Analysis of the cyclic voltammetry suggested that TiO2 film can be reduced to metallic Ti. The sampled current voltammetry was applied to elaborate the reduction mechanism and the results showed that this reduction process may include two steps. When the output potential difference of 2.8 V was applied, a TiO2 cylindrical pellet was partly reduced to metallic Ti. However, due to the very slow reaction rate, there was only about 12 wt% of TiO2 was reduced during the electrolysis time of 48 h. It was predicted that the process for the direct reduction of solid TiO2 would be explained as follows: given enough cathode potential, the reduction happened at the cathode/ionic liquids interface, where the oxygen was ionized, then dissolved in the ionic liquid and discharged at the anode, with the metallic Ti left at the cathode. 相似文献
11.
Lithium-ion batteries should benefit from new polymer-based electrolytes to answer both safety and performance issues for use in transportation applications. Rubber-like gel electrolytes are prepared by gelling of a ionic liquid based solution by a cross-linked epoxide-amine, as a simple and effective means to obtain safe electrolyte materials that exhibit minimal flammability and toxicity while possibly preserving high mechanical and ionic transport properties over a wide temperature window. The synthesis of gel polymer electrolytes based on epoxy-amine thermosetting polymers, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI TFSI) and the lithium salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is presented. Self-standing, transparent, optically homogeneous films are obtained after curing. Two gel polymer electrolytes differing by the nature of the epoxide precursor (aromatic versus aliphatic) are characterized in terms of thermo-mechanical properties with respect to their neat epoxy-amine counterparts. Electrochemical impedance spectroscopy (EIS) is used to investigate the electrical properties and measure the ionic conductivities over the temperature range of interest. The choice of a more flexible moiety in the thermoset precursors leads to an enhanced ionic conductivity. An electric model is presented to predict the gel conductivity on the basis of the conductivity values of neat compounds and to discuss the gel morphology at the molecular scale. 相似文献
12.
D. Pradhan 《Electrochimica acta》2009,54(6):1874-38
Electrochemical production of Ti-Al alloys was investigated using TiCl4-AlCl3-1-butyl-3-methyl imidazolium chloride (BmimCl) electrolytes (molar ratio 0.019:2:1). The experiments were conducted at different temperatures between 70 and 125 ± 3 °C and at various cell voltages between 1.5 and 3.0 V. Morphology and composition of deposited Ti-Al alloys were characterized using scanning electron microscope (SEM), along with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The Ti-Al alloys containing about 15-27 at% Ti were produced with a current efficiency of about 25-38%. TiCl3 passivation on electrodes hinders the deposition kinetics and hence very low cathodic current density and cathodic current efficiency was obtained. This study also focused to determine the effect of process variables such as applied voltage, electrolyte composition and temperature on cathode current density, current efficiency, composition and morphology of Ti-Al alloys. The optimized condition for producing finer particle size and high Ti content in Ti-Al alloys was obtained between the applied voltages of 1.5-2.0 V and temperature ranges from 70 to 100 °C. 相似文献
13.
L.H.S. Gasparotto N. Borisenko O. Hfft R. Al-Salman W. Maus-Friedrichs N. Bocchi S. Zein El Abedin F. Endres 《Electrochimica acta》2009,55(1):218-226
In the present paper the electrodeposition of Ga on Au(1 1 1) from 0.5 mol L−1 GaCl3 in the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py1,4]TFSA, has been investigated by in situ scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and cyclic voltammetry (CV). The CV shows two redox processes: the one at −0.3 V vs. Pt is attributed to a Ga deposition on a Ga layer formed during an electroless deposition process at OCP and/or to the formation of a Au–Ga alloy; the other one at −0.9 V is due to the bulk deposition of Ga. The XPS measurement reveals that there is an oxide layer on the top of the gallium electrodeposit due to exposure to air. In situ STM measurements show that the first layer of the Ga deposit consists of islands of 10–30 nm in width and several nanometers in height surprisingly the result of an electroless deposition at the OCP. If the electrode potential is further reduced the bulk deposition of Ga sets in. 相似文献
14.
15.
开展分子动力学模拟探索不同压力条件下纤维素的基本结构单元--纤维二糖在离子液体1-丁基-3-甲基咪唑氯盐([C4mim]Cl)中的结构动力学特征。研究结果表明,高压环境使二糖分子内氢键网络结构瓦解,二糖与阴阳离子间相互作用增强,形成溶质-溶剂间氢键。借助空间分布函数得到常压及高压环境下二糖分子周围溶剂层分布特征,并通过径向分布函数定量考察了纤维二糖/离子液体体系分子间与分子内的氢键特征,为在化学键水平上认识纤维素在离子液体中溶解机制提供必要的理论基础。 相似文献
16.
Ying Ying Khaw Ching Yern Chee Seng Neon Gan Ramesh Singh Nik Nazri Nik Ghazali Nan-Shang Liu 《应用聚合物科学杂志》2019,136(24):47642
Amphiphilic keratin from chicken feather fiber (CFF) and hydrophilic cellulose were incorporated as fillers into hydrophobic poly(lactic acid) (PLA) polymer blend. This study implemented ionic liquid (IL) of 1-butyl-3-methylimidazolium chloride (BMIMCl) to dissolve the 1 wt % fillers. The composite films were compared with and without the addition of IL prepared from five sets of ratios of CFF to MCC using measuring mixers and compression molding. Thermal analysis showed that increase in CFF composition decreases the glass-transition temperature (T g), and crystallization temperature (T c) as well as increases the degree of crystallinity. PLA composite with the 70/30 ratio of CFF to MCC was found to be the optimum composition in obtaining considerably low T g and high crystallinity. BMIMCl enhanced the miscibility of the composites as observed in scanning electron microscope images and single T g. Apart from creating porous structure and lowering mechanical hardness, BMIMCl also decreased the thermal stability of the PLA composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47642. 相似文献
17.
I. Mukhopadhyay 《Electrochimica acta》2005,50(6):1275-1281
Titanium was electrodeposited from a nominal 0.24 M TiCl4 in l-methyl-3-butyl-imidazolium bis (trifluoro methyl sulfone) imide ([BMIm]BTA) at room temperature on a Au(1 1 1) substrate. The process of electrodeposition was studied by cyclic voltammetry, chrono amperometry and in situ scanning tunneling microscopy (STM). In a first step TiCl4 is reacted to TiCl2, which is subsequently reduced to metallic Ti. Two dimensional (2D) clusters form preferentially on the terraces in the under potential deposition range. 2D clusters presumably of TiCl3 precipitates grow and coalesce to cover the whole substrate with a 2D film at a substrate potential below −1.1 V versus ferricenium/ferrocene ([Fc]+/[Fc]) redox couple. At a potential of −1.8 V a dense layer of three dimensional (3D) clusters of titanium of 1-2 nm thickness is formed. The features of the I-U tunneling spectra and the relative reduction of the effective tunneling barrier by 0.8 eV with respect to gold clearly indicate the metallic character of Ti deposits. Observation of circular holes on the Au(1 1 1) substrate after dissolution of the deposited Ti indicates the formation of Au-Ti surface alloying. 相似文献
18.
Ki-Sub Kim Dorjnamjin Demberelnyamba Bae-Kun Shin Sun-Hwa Yeon Sukjeong Choi Jong-Ho Cha Huen Lee Chul-Soo Lee Jae-Jin Shim 《Korean Journal of Chemical Engineering》2006,23(1):113-116
The surface tension and viscosity of 1-butyl-3-methylimidazolium iodide ([bmim][I]) and 1-butyl-3-methylimidazolium tetrafluoroborate
([bmim][BF4]) were measured over a temperature range of 298. 15 to 323.15 K. It was found that both the viscosity and surface tension
decrease with increasing temperature and that the surface tension and viscosity values of [bmim][I] were higher than those
of [bmim][BF4]. Additionally, the solubility of lithium bromide (2)+1-butyl-3-methylimidazolium bromide ([bmim][Br]) (3) in water (1) was
measured at three different mass ratios (w2/w3=4 and 7, w3=0) by using a visual polythermal method. The solubility of the suggested systems was better than that of lithium bromide
in water. 相似文献
19.
Cathodic copper is easily contaminated by antimony in copper electrowinning from chloride solutions even when the antimony concentration in the electrolyte is as low as 2 p.p.m. Reduction potential measurements of copper and antimony species indicate that electrodeposition of antimony is unlikely unless copper concentration polarization exists near the cathode surface. A.c. impedance measurements and the effect of the rotation speed of the disc electrode indicate that the cathodic process mechanism for antimony is complicated. Both diffusion and chemical reactions occurring on the cathode surface supply the electrochemical active antimony species for the cathodic process. Reaction orders of the cathodic process with respect to antimony chloride, hydrogen and chloride ion concentrations are 2, –1 and –1, respectively. A proposed reaction mechanism for the process explains the experimental findings satisfactorily.List of symbols
A
surface area (cm2)
- ao1, a1
constants
-
C
concentration (mol cm–3)
-
D
diffusion coefficient (cm2 s–1)
-
E
potential (V)
-
F
Faraday constant (Cmol–1)
-
f
frequency (s–1)
-
I
current (A)
-
i
current density (A cm–2)
-
i
d
8
limiting diffusion current density due to the diffusion of species O from bulk to the electrode surface and then the subsequent Reac tions 1 and 2 (A cm–2)
-
i
d
o
limiting diffusion current density of species O (A CM–2)
-
K
chemical equilibrium constant
-
k
rate constant (s–1)
-
n
number of electrons involved in the reaction
-
Q
charge (C)
-
Q
dl
charge devoted to double layer capacitance (C)
-
Q
f
total charge in the forward step of potential step chronocoulometry (C)
-
Q
r
total charge in reverse step of potential step chronocoulometry (C)
-
t
time (s)
-
sweep rate (V s–1)
Greek symbols
amount of species adsorbed per unit area (mol cm–2)
-
fraction of adsorption sites on the surface occupied by adsorbate.
-
ratio of rate constant defined in Equation 1
- c
thickness of reaction layer (cm)
- d
thickness of diffusion layer (cm)
-
time (s)
-
modified time (s1/2)
-
kinematic viscosity (cm2 s–1)
-
angular velocity (s–1) 相似文献
20.
Luciano T. Costa Raquel S. Borges Glaura G. Silva Mauro C.C. Ribeiro 《Electrochimica acta》2007,53(4):1568-1574
Polymer electrolytes based on poly(ethylene glycol) dimethyl ether (PEGdME) and the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) have been prepared and characterized by different techniques. Coordination of the IL by the polymer occurs mainly in the amorphous phase. This finding was correlated with previous theoretical investigations of a similar model for polymer electrolytes based on poly(ethylene oxide), PEO, and IL. It has been obtained ionic conductivity σ ∼ 10−3 S cm−1 for the polymer electrolyte with 35 wt% of IL at 100 °C. The same order of magnitude for σ was obtained by molecular dynamics simulation of PEO/IL. This work demonstrates consistency between experimental and theoretical results for polymer electrolytes containing ionic liquids. 相似文献