聚噻吩在离子液体中的电化学合成研究

Polythiophene（PTh）films were prepared by the direct electropolymerization of thiophene in the ionic liquid,1-butyl-3-methylimidazolium hexafluorophosphate（BMIM）PF6 . The structure and morphology of PTh films were characterized by means of the FT-IR spectrum and the scanning electron microscopy（ SEM）. The electrical and electrochemical properties of PTh films were examined with the UV-Vis spectrum,cyclic voltammetry（CV） and four-probe method. The results showed that when the potential for electropolymerization was controlled between +1.7 and +1.9 V（vs. Ag/AgCl）,very homogeneous PTh films could be prepared in the ionic liquid （BMIM）PF6 used as solvent and electrolyte. The de-doping（reduction）and re-doping（re-oxidation）of the PTh film prepared in ionic liquid are reversible and stable,and the conductivity of PTh films is 0.01-0.1 S/cm.     

共晶基离子液体的钴电化学沉积

通过恒电流和恒电位方法,研究了不同温度下脲-氯化胆硷（氯仿）基或乙二醇-氯化胆硷（氯仿）基离子液体中氯化钴溶液在铜和钢阴极上的钴电化学沉积行为. 采用扫描电子显微镜和X射线衍射技术,考察了不同试验条件对钴电沉积行为及钴沉积层形貌的影响. 结果表明,当沉积电位达到-0.8 V和沉积电流密度达到-6.0 A·m^-2时,温度范围从30 °C到90 °C,添加0.05 mol·L^-1的五氧化二磷,可以从脲基和乙二醇基离子液体中沉积得到光滑、发亮和良好结合力的金属光泽钴层. 电化学沉积钴的阴极电流效率达到98%.     

塑晶基离子液体合成及其电化学性能

通过简单、易于工业化的重结晶方法制备了高纯1-甲基-1-乙基吡咯烷鎓双(三氟甲基磺酰)亚胺盐(P₁₂TFSI)塑晶化合物. 在此化合物中加入30% (摩尔分数, x)双(氟磺酰)亚胺锂(LiFSI)后, 得到P₁₂TFSI/LiFSI 塑晶基离子液体. 采用循环伏安法、恒电压极化法及恒电流充放电法等电化学方法考察了该离子液体的电化学窗口、铝箔集流体的腐蚀性及电池性能. 结果表明, 该离子液体电解质具有5.00 V的电化学窗口, 室温离子电导率达到0.92 mS·cm^-1, 且不腐蚀Al 集流体. 以该塑晶离子液体作为电解液组装的实验电池LiCoO₂/Li 表现出良好的充放电特性及循环性能, 在较低倍率下能够和使用碳酸酯类电解液组装的实验电池的性能相媲美. 在4.50 V高电压下, 循环20周后, 容量仍能保持在175 mAh·g^-1, 容量保持率为95.1%. 这些结果说明该离子液体在高性能锂二次电池中具有良好的应用前景.     

基于氯化胆碱离子液体的铜电沉积研究（英文）

采用恒电流和恒电位方法,基于含有氯化铜溶液的乙二醇-氯化胆碱或硫脲-氯化胆碱离子液体,室温下在钢阴极上进行了铜的电沉积. 利用扫描电子显微镜和X-射线衍射技术研究了各种实验条件对电沉积的影响以及沉积层的形貌. 结果表明,室温下施加不超过-0.45 V的沉积电位和不超过-4.0 A·m^-2的沉积电流密度,可以同时从氯化胆碱基乙二醇和硫脲离子液体中沉积得到非常光滑、有光泽、致密且具有良好结合力、色泽鲜艳的铜金属涂层. 铜的电沉积阴极电流效率约为97%.     

3-甲基噻吩在离子液体 BMIMPF6中的电化学聚合、表征及应用

Poly-3-methylthiophene （P3MT） was synthesized in the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate （[BMIM]PF6） by constant potential and constant current respectively. The structure and morphology of P3MT films were characterized by FTIR spectrum and SEM. The undoped （reduction） and doped （oxidation） forms of P3MT film prepared in ionic liquid were reversible and stable. The P3MT film has strong characteristics of electrocatalytic oxidation of ascorbic acid and can separate the oxidation peaks of ascorbic acid and dopamine. Two methods of potential steps were used to observe the response time of the film and the film was found to have perfect electrochromic response.     

离子液体AlCl3/Et3NHCl中电沉积法制备金属铝

在AlCl3/Et3NHCl型离子液体中铝电极上通过恒电位电解沉积制备出金属铝. 测定了不同摩尔比的AlCl3/Et3NHCl离子液体在不同温度下的电导率, 考察了离子液体AlCl3/Et3NHCl摩尔比为2/1中Al电极上铝沉积的晶核成核过程, 以及恒电位电解沉积铝的工艺条件对电流效率和沉积铝表面形貌的影响. 结果表明, 不同比例AlCl3/Et3NHCl离子液体的电导率随温度升高而升高, 符合Arrhenius规律; 在Al电极上铝沉积的成核机理为三维瞬时成核过程; 恒电位电解沉积结果表明, 室温下在电位-2.4 V(vs Pt)和电解时间20 min条件下, 沉积铝的表面形貌比较平整致密,电流效率达73%, 沉积铝的纯度达96%(w).     

Supported ionic liquid phase rhodium nanoparticle hydrogenation catalysts

Rh(0) nanoparticles (ca. 4 nm) dispersed in an ionic liquid (1-n-butyl-3-methylimidazolium tetrafluoroborate) were immobilized within a silica network, prepared by the sol-gel method. The effect of the sol-gel catalyst (acid or base) on the encapsulated ionic liquid and Rh(0) content, on the silica morphology and texture, and on the catalyst alkene hydrogenation activity was investigated. The Rh(0) content in the resulting xerogels (ca. 0.1 wt% Rh/SiO(2)) was shown to be independent of the sol-gel process. However, acidic conditions afforded higher contents of encapsulated ionic liquid and xerogels with larger pore diameters, which in turn might be responsible for the higher catalyst activity in hydrogenation of the alkenes.     

Preparation,Characterization and Electromagnetic Shielding Effectiveness of Conductive Polythiophene/Poly(ethylene terephthalate) Composite Fibers

Conductive polythiophene (PTh)/poly(ethylene terephthalate) (PET) composite fibers were prepared by polymerization of thiophene in the presence of PET fibers in acetonitrile medium using FeCl₃. The effects of polymerization conditions such as oxidant/monomer mol ratio and polymerization temperature and time on PTh content and surface electrical resistivity of PTh/PET composite fiber were investigated in detail. It was observed that the usage of preswelled PET fibers in dichloromethane increased the PTh content and decreased surface resistivity of composite fiber. Composite fiber having the highest PTh content (5.7%) and the lowest surface resistivity (80 kΩ) was obtained at 20°C with 1.25 M FeCl₃ and 0.42 M thiophene concentrations. The washing effects of laundering detergent and dry cleaning liquid on surface resistivity of composite fibers were investigated. The electromagnetic shielding effectiveness (EMSE) and relative shielding efficiency by absorption and reflection of composite fibers were measured in the radio and microwave frequency range. The results show that the EMSE values decreased with increasing frequency from radio waves to microwaves with an attenuation of 21 dB to 4 dB.     

Immobilization of invertase in conducting copolymers of 3-methylthienyl methacrylate

Immobilization of invertase in conducting copolymer matrices of 3-methylthienyl methacrylate with pyrrole and thiophene was achieved by constant potential electrolysis using sodium dodecyl sulfate (SDS) as the supporting electrolyte. Polythiophene (PTh) was also used in entrapment process for comparison. Kinetic parameters, Michaelis-Menten constant, K(m), and the maximum reaction rate, V(max), were investigated. Operational stability and temperature optimization of the enzyme electrodes were also examined.     

Synthesis and Characterization of Multi‐Walled Carbon Nanotube/Polythiophene Composites

Multi‐walled carbon nanotube (MWCNT)/polythiophene (PTh) composites have been prepared by in situ chemical oxidative polymerization. PTh is synthesized onto the sidewalls of the MWCNTs, which play a role as hard templates for PTh to produce one‐dimensional nanostructures. The morphology and structures of the MWCNT/PTh composites are characterized by High‐resolution transmission electron microscopy, x‐ray diffraction, and Fourier transform infrared spectrometry. Their electrical property and thermal stability are determined using vector network analyzer and thermal gravimetric analyzer. Moreover, the mechanism of MWCNT/PTh nanowire formation is described. The studies show that the composites are nanowires with core‐shell structure, in which the outer shells and inner cores are formed by PTh and MWCNTs, respectively. The addition of MWCNTs does not change the backbone structure of PTh and affect the amorphous condition of PTh very slightly, however, it improves the electrical conductivity and thermal stability of PTh.     

离子液体在多孔碳电极上的电化学性能

制备了数种离子液体及离子液体有机溶液电解质,用线性电位扫描法测试了它们的电化学窗口;并通过循环伏安、交流阻抗、电势阶跃等电化学方法,对它们在多孔碳电极中的电化学性能进行了研究.实验结果表明:溶剂对1-乙基-3-甲基咪唑类离子液体有机溶液电解质的电化学窗口有较大的影响.离子液体及离子液体有机溶液电解质在多孔碳电极上的电化学性能与其电导率密切相关,电导率越大,充电时间常数越小,比容量越大;但比容量降低的倍率远小于电导率降低的倍率.     

Safety-enhanced Polymer Electrolytes with High Ambient-temperature Lithium-ion Conductivity Based on ABA Triblock Copolymers

Liquid electrolytes used in lithium-ion batteries suffer from leakage,flammability,and lithium dendrites,making polymer electrolyte a potential alternative.Herein,a series of ABA triblock copolymers(ABA-x)containing a mesogen-jacketed liquid crystalline polymer(MJLCP)with a polynorbornene backbone as segment A and a second polynorbornene-based polymer having poly(ethylene oxide)(PEO)side chains as segment B were synthesized through tandem ring-opening metathesis polymerizations.The block copolymers can self-assemble into ordered morphologies at 200℃.After doping of lithium salts and ionic liquid(IL),ABA-x self-assembles into cylindrical structures.The MJLCP segments with a high glass transition temperature and a stable liquid crystalline phase serve as physical crosslinking points,which significantly improve the mechanical performance of the polymer electrolytes.The ionic conductivity of ABA-x/lithium salt/IL is as high as 10-3 S·cm-1 at ambient temperature owing to the high IL uptake and the continuous phase of conducting PEO domains.The relationship between ionic conductivity and temperature fits the Vogel-Tamman-Fulcher(VTF)equation.In addition,the electrolyte films are flame retardant owing to the addition of IL.The polymer electrolytes with good safety and high ambient-temperature ionic conductivity developed in this work are potentially useful in solid lithium-ion batteries.     

Influence of the ionic liquid/gas surface on ionic liquid chemistry

Applications such as gas storage, gas separation, NP synthesis and supported ionic liquid phase catalysis depend upon the interaction of different species with the ionic liquid/gas surface. Consequently, these applications cannot proceed to the full extent of their potential without a profound understanding of the surface structure and properties. As a whole, this perspective contains more questions than answers, which demonstrates the current state of the field. Throughout this perspective, crucial questions are posed and a roadmap is proposed to answer these questions. A critical analysis is made of the field of ionic liquid/gas surface structure and properties, and a number of design rules are mined. The effects of ionic additives on the ionic liquid/gas surface structure are presented. A possible driving force for surface formation is discussed that has, to the best of my knowledge, not been postulated in the literature to date. This driving force suggests that for systems composed solely of ions, the rules for surface formation of dilute electrolytes do not apply. The interaction of neutral additives with the ionic liquid/gas surface is discussed. Particular attention is focussed upon H(2)O and CO(2), vital additives for many applications of ionic liquids. Correlations between ionic liquid/gas surface structure and properties, ionic liquid surfaces plus additives, and ionic liquid applications are given.     

Determination of 3, 4-dihydroxybenzoic acid by electrocatalytic oxidation at an ionic liquid modified electrode

An electrode modified with an ionic liquid was used for the electrochemical determination of 3,4-dihydroxybenzoic acid (DHBA). Cyclic voltammetry indicated a pair of well-defined quasi-reversible redox peaks with a formal peak potential located at 586 mV (vs. the SCE). The voltammetric response to DHBA is largely improved compared to a traditional carbon paste electrode. This is attributed to a larger interface (due to the presence of an ionic liquid) with higher conductivity and inherent catalytic capability. The charge transfer coefficient, the standard rate constant and the apparent diffusion coefficient were calculated. The oxidation peak current was linearly related to the concentration of DHBA in the range 0.8–1.5 mM, and the detection limit was 0.62 µM (at 3σ). The effect of potential interferents was investigated, and the method was successfully applied to the determination of DHBA in different samples.

     

Capacity of graphene anode in ionic liquid electrolyte

The graphene anode was investigated in an ionic liquid electrolyte (0.7 M lithium bis(trifluoromethanesulfonyl)imide (LiNTf₂)) in room temperature ionic liquid (N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPyrNTf₂)). SEM and TEM images suggested that the electrochemical intercalation/deintercalation process in the ionic liquid electrolyte without vinylene carbonate (VC) leads to small changes on the surface of graphene particles. However, a similar process in the presence of VC results in the formation of a coating (SEI—solid electrolyte interface) on the graphene surface. During charging/discharging tests, the graphene electrode working together with the 0.7 M LiNTf₂ in MPPyrNTf₂ electrolyte lost its capacity, during cycling and stabilizes at ca. 200 mAh g^?1 after 20 cycles. The addition of VC to the electrolyte (0.7 M LiNTf₂ in MPPyrNTf₂?+?10 wt.% VC) considerably increases the anode capacity. Electrodes were tested at different current regimes: ranging between 50 and 1,000 mA g^?1. The capacity of the anode, working at a low current regime of 50 mA g^?1, was ca. 1,250 mAh g^?1, while the current of 500 mA g^?1 resulted in capacity of 350 mAh g^?1. Coulombic efficiency was stable and close to 95 % during ca. 250 cycles. The exchange current density, obtained from impedance spectroscopy, was 1.3?×?10^?7 A cm^?2 (at 298 K). The effect of the anode capacity decrease with increasing current rate was interpreted as the result of kinetic limits of the electrode operation.     

Supported ionic liquid phase-boosted highly active and durable electrocatalysts towards hydrogen evolution reaction in acidic electrolyte

Platinum is generally known as the most effective electrocatalyst for hydrogen evolution reaction because it can greatly lower the overpotential and accelerate the reaction kinetics,while its commercial potential always suffers from scarcity,high cost,low utilization,and poor durability particularly in acidic electrolytes.We herein demonstrate a facile method to improve the hydrogen evolution performance of Pt-based electrocatalysts by simply decorating the-state-of-the-art and commercially available Pt/C with hydrophobic protic([DBU][NTf2])or aprotic([BMIm][NTf2])ionic liquid.The current densities of[BMIm]@Pt/C and[DBU-H]@Pt/C with 10% ionic liquid at an overpotential of 40 mV are 2.81 and 4.15 times,respectively,higher than that of the pristine Pt/C.More importantly,ionic liquid-decoration significantly improves the long-term stability of Pt nanoparticles.After 8 h of chronoamperometric measurements,[DBU-H]@Pt/C and[BMIm]@Pt/C can still retain 83.7% and 78.3% of their original activity,respectively,which is much higher than that of the pristine Pt/C(24.4%).The improved performance of Pt/C decorated with ionic liquid is considered to arise from the improved proton conductivity(particularly for protic ionic liquid)and hydrophobic microenvironment created by the supported ionic liquid phase.The presence of ionic liquid layer not only de-coordinates H+from hydronium ions nearby the Pt nanoparticles,but it also protects Pt nanoparticles from dissolution in the acidic media.     

Electrosynthesis of Poly(para)phenylene in an Ionic Liquid: Cyclic Voltammetry and in Situ STM/Tunnelling Spectroscopy Studies

The electropolymerization of benzene in the air and water‐stable ionic liquid 1‐hexyl‐3‐methylimidazolium tris(pentafluoroethyl)trifluorophosphate (HMIm)FAP is investigated. The study comprises cyclic voltammetry, IR and in situ STM/tunnelling spectroscopy measurements. The IR results indicate that poly(para)phenylene is the end product of the electropolymerization of benzene in the employed ionic liquid. The resulting conjugation lengths of the product fall between 19 and 21. A polymer reference electrode is used successfully for the electrochemical polymerization of benzene. The first in situ STM results show that the electropolymerization of benzene in the ionic liquid can be probed on the nanoscale and the band gap of the prepared polymer can be determined. The electrodeposited polymer film obtained at a constant potential of 1.0 V vs PPP (polyparaphenylene) exhibits a band gap of 2.9±0.2 eV.     

Electrodeposition of Aluminum from AlCl3/Et3NHCl Ionic Liquids

Aluminum was successfully electrodeposited on Al electrodes from aluminum chloride (AlCl₃)/triethylamine hydrochloride (Et₃NHCl) ionic liquids by the constant potential electrolysis. Electrical conductivities of AlCl₃/Et₃NHCl ionic liquids were measured as a function of the temperature and composition. The nucleation processes and the influence of experimental conditions on the current efficiency and surface morphology of aluminum electrodeposits were studied on Al electrodes from 2:1 molar ratio AlCl₃/Et₃NHCl ionic liquid. The electrical conductivities of ionic liquids increased as the electrolyte temperature increased, following the Arrhenius behavior. Analyses of the chronoamperograms indicated that the deposition process of aluminum on Al substrates was controlled by instantaneous nucleation with diffusion-controlled growth. Constant potential deposition experiments showed that the electrodeposits obtained on Al electrodes were dense, continuous, and well adherent, and the current efficiency was 73% at −2.4 V(vs Pt) for 20 min electrolysis at room temperature. The purity of aluminum electrodeposits on Al electrodes was above 96% (w).     

Ionic liquid analogues formed from hydrated metal salts

A dark green, viscous liquid can be formed by mixing choline chloride with chromium(III) chloride hexahydrate and the physical properties are characteristic of an ionic liquid. The eutectic composition is found to be 1:2 choline chloride/chromium chloride. The viscosity and conductivity are measured as a function of temperature and composition and explained in terms of the ion size and liquid void volume. The electrochemical response of the ionic liquid is also characterised and it is shown that chromium can be electrodeposited efficiently to yield a crack-free deposit. This approach could circumvent the use of chromic acid for chromium electroplating, which would be a major environmental benefit. This method of using hydrated metal salts to form ionic liquids is shown to be valid for a variety of other salt mixtures with choline chloride.     

Size and shape of Au nanoparticles formed in ionic liquids by electron beam irradiation

Au nano-particles were synthesized via a reductive reaction in ionic liquid solution containing Au(3+) ions using a low-energy electron irradiation technique. In this study, we focused on how the electron beam conditions (acceleration energy, beam current and irradiation time) and the kinds of ionic liquid affected the size and shape of the prepared Au particles. The sizes of the primary particles increased with higher acceleration energy of the electron beam, whereas they did not depend so much on the beam current. Although the amount of secondary particles increased with longer irradiation time, the sizes of the primary particles remained constant. The anion of the ionic liquid strongly affected the size and shape of the primary particles, which was due to the different local structure of the ionic liquid around the Au particles. When the thickness of the ionic liquid layer was smaller than the penetration length of the electron beam, the formation of secondary particles was suppressed. The present results gave an important knowledge for controlling the size and shape of the metal particles, which is important for application of various catalyst or devices.