Carbon Nanotube Ionic Liquid Research Articles

Novel alcohol sensor based on PtRuNi ternary alloy nanoparticles–multi-walled carbon nanotube–ionic liquid composite coated electrode

A novel alcohol sensor was proposed in the present work, which was based on the pulsed electrodeposition of PtRuNi ternary alloy nanoparticles on multi-walled carbon nanotubes (MWNTs)–ionic liquid (IL, i.e. 1-octyl-3-methylimidazolium hexaflurophosphate, OMIMPF 6) gel film. The composition, morphology and catalytic activity of the obtained nanoparticles were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and voltammetry, respectively. The PtRuNi–MWNT–IL coated glassy carbon electrode was proved to be suitable for detecting alcohol. The analytical characteristics of the resulting sensor, in terms of poison tolerance, response time, linear range, detection limit, sensitivity, reproducibility and long-term stability were explored and satisfying results were obtained. For comparison, the electrodes with PtRuCo, PtRu and Pt nanoparticles were also prepared and studied.

Nonenzymatic glucose sensor based on ultrasonic-electrodeposition of bimetallic PtM (M = Ru, Pd and Au) nanoparticles on carbon nanotubes–ionic liquid composite film

We report here for the first time on the fabrication of highly dispersed PtM (M = Ru, Pd and Au) nanoparticles on composite film of multi-walled carbon nanotubes (MWNTs)–ionic liquid (IL, i.e., trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide) by using ultrasonic-electrodeposition method. The PtM nanoparticles are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction, and we find that they are well-dispersed and exhibit alloy properties. Electrochemical experiments show that the PtRu(1:1, i.e., ratio of c(H 2PtCl 6)/c(RuCl 3))–MWNT–IL nanocomposite modified glassy carbon electrode (PtRu(1:1)–MWNT–IL/GCE) has smaller electron transfer resistance and larger active surface area than PtRu(1:1)/GCE, PtRu(1:1)–MWNT/GCE, PtPd(1:1)–MWNT–IL/GCE and PtAu(1:1)–MWNT–IL/GCE. The PtRu(1:1)–MWNT–IL/GCE also presents stronger electrocatalytic activity toward the glucose oxidation than other electrodes. At −0.1 V, the electrode responds linearly to glucose up to 15 mM in neutral media, with a detection limit of 0.05 mM (S/N = 3) and detection sensitivity of 10.7 μA cm −2 mM −1. Meanwhile, the interference of ascorbic acid, uric acid, acetamidophenol and fructose is effectively avoided. The as-made sensor was applied to the determination of glucose in serum and urine samples. The results agreed closely with the results obtained by a hospital. This novel nonenzyme sensor thus has potential application in glucose detection.

Ni(II)–quercetin complex modified multiwall carbon nanotube ionic liquid paste electrode and its electrocatalytic activity toward the oxidation of glucose

A modified electrode Ni(II)–Qu–MWCNT–IL–PE has been fabricated by electrodepositing Ni(II)–quercetin [Ni(II)–Qu] complex on the surface of multi-wall carbon nanotube ionic liquid paste electrode (MWCNT–IL–PE) in alkaline solution. The Ni(II)–Qu–MWCNT–IL–PE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple compared with Ni(II)–Qu–MWCNT–PE. It also shows good electrocatalytic activity toward the oxidation of glucose. Kinetic parameters such as the electron transfer coefficient α, rate constant k s of the electrode reaction and the catalytic rate constant k cat of the catalytic reaction are determined. Moreover, the catalytic current presents linear dependence on the concentration of glucose from 5.0 μM to 2.8 mM, with a detection limit of 1.0 μM by amperometry. The modified electrode for glucose determination is of the property of simple preparation, good stability, fast response and high sensitivity.

Selective Band Structure Modulation of Single-Walled Carbon Nanotubes in Ionic Liquids

A simple method was developed for the reversible and selective modification of metallic and large diameter semiconducting SWCNTs in [BMIM]PF(6) ionic liquids by adding certain anion surfactants. The electronic band structure of SWCNTs can be controlled and tuned over a range by varying the surfactants used and their concentrations. A charge transfer "cation- product operator" complex model was proposed. This method is mild without damaging the structure of SWCNTs.

Direct electrochemistry and electrocatalysis of cytochrome c based on chitosan–room temperature ionic liquid-carbon nanotubes composite

A robust and effective composite film combined the benefits of room temperature ionic liquid (RTIL), chitosan (Chi) and multi-wall carbon nanotubes (MWNTs) was prepared. Cytochrome c (Cyt c) was successfully immobilized on glassy carbon electrode (GCE) surface by entrapping in the composite film. Direct electrochemistry and electrocatalysis of immobilized Cyt c were investigated in detail. A pair of well-defined and quasi-reversible redox peaks of Cyt c was obtained in 0.1 mol L −1 pH 7.0 phosphate buffer solution (PBS), indicating the Chi–RTIL–MWNTs film showed an obvious promotion for the direct electron transfer between Cyt c and the underlying electrode. The immobilized Cyt c exhibited an excellent electrocatalytic activity towards the reduction of H 2O 2. The catalysis current was linear to H 2O 2 concentration in the range of 2.0 × 10 −6 to 2.6 × 10 −4 mol L −1, with a detection limit of 8.0 × 10 −7 mol L −1 (S/N = 3). The apparent Michaelis–Menten constant ( K m) was calculated to be 0.45 ± 0.02 mmol L −1. Moreover, the modified electrode displayed a rapid response (5 s) to H 2O 2, and possessed good stability and reproducibility. Based on the composite film, a third-generation reagentless biosensor could be constructed for the determination of H 2O 2.

Single-walled carbon nanotube-ionic liquid paste electrode for the sensitive voltammetric determination of folic acid

Abstract A single-walled carbon nanotube (SWNT) paste coated glassy carbon electrode (GCE) has been prepared by using room temperature ionic liquid (i.e. 1-octyl-3-methylimidazolium hexafluorophosphate, OMIMPF 6 ) as a binder. The electrode (i.e. OMIMPF 6 –SWNT/GCE) combines the features of carbon nanotube and room temperature ionic liquid. Folic acid (FA) can exhibit a very sensitive anodic peak at 0.75 V (vs SCE) in pH 5.5 phosphate buffer solutions, resulting from the irreversible oxidation of FA. Under the optimized conditions, the peak current is linear to FA concentration over the range of 2.0 × 10 −9 to 4.0 × 10 −6 M by using differential pulse voltammetry, and the detection limit is 1.0 × 10 −9 M (S/N = 3). The OMIMPF 6 –SWNT/GCE is successfully applied to the determination of FA in real samples.

Characterization of hydrophobic ionic liquid-carbon nanotubes–gold nanoparticles composite film coated electrode and the simultaneous voltammetric determination of guanine and adenine

Abstract A novel composite film, comprising of hydrophobic ionic liquid (IL), multi-walled carbon nanotubes (MWNTs) and gold nanoparticles (GNP), was fabricated and characterized. The GNP was introduced through electrochemical deposition on IL–MWNT gel film coated glassy carbon electrodes (GCE). Experiments showed that both IL and MWNTs could facilitate the GNP deposition. With GNP the composite film exhibited smaller electron transfer resistance and higher sensitivity in sensing guanine (G) and adenine (A). Under the optimized experimental conditions, the anodic peak currents were linear to the analyte concentration in the ranges of 0.008–2.0 μM. The detection limits were down to nanomole level after an accumulation of 150 s on open-circuit. In addition, on the composite film coated GCE, the anodic peaks of G and A were well separated, and their response sensitivities kept almost unchanged no matter whether they coexisted or not. This proposed procedure was successfully applied to the detection of G and A in milk, plasma and urine samples.

Superior Capacitive Performance of Aligned Carbon Nanotubes in Ionic Liquids

Electrodes and electrolytes are two essential components of a supercapacitor and play important roles in determining the performance for the supercapacitor. In the present work, we investigated the electrochemical and capacitive behavior of aligned carbon nanotube electrodes in ionic liquid electrolytes to study the feasibility to develop high performance supercapacitors from these two components. Synthesis procedure of the carbon nanotubes and composition of the ionic liquids have been studied to achieve a high capacitance and fast charge/discharge process for the carbon nanotube electrode in the ionic liquid electrolyte.

Analysis of sudan I, sudan II, sudan III, and sudan IV in food by HPLC with electrochemical detection: Comparison of glassy carbon electrode with carbon nanotube-ionic liquid gel modified electrode

A method was developed for analyzing of sudan I, sudan II, sudan III, and sudan IV by high performance liquid chromatography coupled with an electrochemical detector. The electrochemical oxidation of each compound was investigated with a carbon nanotube-ionic liquid gel modified glassy carbon (MWNTs-IL-Gel/GC) electrode using cyclic voltammetry. The results were compared with those of glassy carbon electrodes. At the MWNTs-IL-Gel/GC electrode, highly reproducible, well-defined cyclic voltammograms for sudan oxidation were obtained. In the flow system, MWNTs-IL-Gel/GC exhibited highly reproducible and well-defined amperometric signals without peak tailing. In addition, the determination of sudan dyes by mean of isocratic reverse-phase HPLC, with amperometric detection at MWNTs-IL-Gel/GC and GC electrode, have been investigated. The chromatograms showed excellent separation. The detection limits ranged from 0.001 to 0.005ppm. The method was sensitive, selective and could be applicable for the assay of sudan dyes in soft drink samples.

Structural and characteristic analysis of carbon nanotubes-ionic liquid gel biosensor

The structure and characteristic of carbon nanotubes-ionic liquid gel biosensor were studied by voltammetry, microscopy and spectroscopy. Various biomolecules were electrochemically detected with this gel biosensor such as glucose oxidase and NADH. The excellent electrochemical behavior of this gel biosensor might be due to the following three main factors: (1) the inherently perfect electrochemical characteristic of multi-wall carbon nanotubes (MWNTs); (2) the better solvent effect and conductivity of ionic liquid as well as the proper interactions between MWNTs and ionic liquid; (3) the proper mixing ratio of MWNTs to ionic liquid. Meanwhile, the interactions between MWNTs and ionic liquid were carefully studied as well. It can be concluded that the non-covalent (π–π) interaction between the imidazole loop of ionic liquid and MWNTs side wall should play an important role. This work gives a further understanding of what results in the high sensitivity and selectivity of such a biosensor to some biomolecules, and provides a simple and easy approach to design new biosensors with various nano-particles and versatile ionic liquid.

Electrochemical catalysis and thermal stability characterization of laccase–carbon nanotubes-ionic liquid nanocomposite modified graphite electrode

The hydrophobic carbon nanotubes-ionic liquid (CNTs-IL) gel forms a stable modified film on hydrophobic graphite electrode surface. Laccase immobilized on the CNTs-IL gel film modified electrode shows good thermal stability and enhanced electrochemical catalytic ability. The optimal bioactivity occurs with increasing temperature and this optimum is 20 °C higher in comparison to free laccase. The improvement of laccase thermal stability may be due to the microenvironment of hydrophobic CNTs-IL gel on graphite electrode surface. On the other hand, the sensitive detection of oxygen has been achieved due to the feasibility of oxygen reduction by both of laccase and nanocomposite of CNTs-IL gel. Furthermore, the laccase hybrid nanocomposite also shows the fast electrochemical response and high sensitivity to the inhibitors of halide ions with the approximate IC 50 of 0.01, 4.2 and 87.5 mM for the fluoride, chloride and bromide ions, respectively. It implies the feasibility of laccase modified electrode as an inhibition biosensor to detect the modulators of laccase.

Superior Capacitive Performance of Aligned Carbon Nanotubes in Ionic Liquids

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A biofuel cell with enhanced power output by grape juice

Glucose oxidase and laccase immobilized at multiwalled carbon nanotubes-ionic liquid gel modified electrodes are used as the catalysts of anode and cathode of biofuel cells (BFCs), respectively. The BFC based on glucose and air is proposed. When ferrocene monocarboxylic acid is adopted as the mediator of anode, the power output of the BFC is ca. 4.1 μW (power density ca. 10.0 μW cm−2), which is higher than the value of 2.7 μW (power density ca. 6.6 μW cm−2) by taking ferrocene dicarboxylic acid as the mediator. This implies that the mediator with formal potential closing to that of the enzyme does improve the power output. Furthermore, the power output of the BFC is greatly improved by taking grape juice as the fuel of anode rather than glucose. This system also indicates that grape juice as a fuel of the BFC not only is feasible and can also enhances the power output of the BFCs. Besides, it greatly lowers the cost and simplifies the preparation procedure of the BFCs, making the BFC towards “green” bioenergy.

Electrochemical characteristics of facile prepared carbon nanotubes–ionic liquid gel modified microelectrode and application in bioelectrochemistry

The carbon nanotubes (CNTs) based microelectrode (ME) by modifying CNTs-room temperature ionic liquid (IL) gel at carbon fiber microelectrode (CFME) is easily prepared, which exhibits the typical cyclic voltammogram of ME with sigmoid shape and possesses good stability, high conductivity and enlarged current response and tunable dimension. The direct electron transfer of glucose oxidase has been greatly promoted showing reversible electrochemical behavior even at high scan rate. In addition, the CNTs based ME also exhibits effectively electrocatalytic oxidized ability to biomolecules, e.g. dopamine (DA), ascorbic acid (AA) and dihydronicotinamide adenine dinucleotide. The obvious separation of oxidized peak potential for DA and AA makes it possible to selectively determine DA in presence of AA. These phenomena show that the CNTs based ME has promising potential to detect various species in vivo and in vitro.

Microwave-Assisted Synthesis of Pt Nanocrystals and Deposition on Carbon Nanotubes in Ionic Liquids

In this work, a simple, fast and efficient route is presented for the metal (such as Pt, Rh, etc.) nanocrystal synthesis and deposition on carbon nanotubes (CNTs) in ionic liquids (ILs) via microwave heating. In this method, inorganic salts (such as H2PtCl6.4H2O, RhCl3.2H2O, etc.) dissolved in ILs, 1,1,3,3-tetramethylguanidinium trifluoroacetate or 1,1,3,3-tetramethylguanidinium lactate, were reduced to metal nanoparticles by glycol with the aid of microwave heating, and the produced metal nanoparticles could be decorated on CNTs in the presence of CNTs in ILs. The resulting nanomaterials were characterized by means of transmission electron microscopy and X-ray diffraction. It was demonstrated that the homogeneously dispersed Pt nanocrystals with the size of 2-3 nm were obtained using H2PtCl6.4H2O as precursor, and they deposited on CNTs with the similar size when CNTs was present in ILs. This technique also can be extended to fabricate other noble metal nanocrystals (including Rh, Au, etc.) and corresponding CNT composites.

125 カーボンナノチューブとイオン液体からなる高分子アクチュエータの応答性能(知的材料・構造システム)

125 カーボンナノチューブとイオン液体からなる高分子アクチュエータの応答性能(知的材料・構造システム)

Green Chemical Functionalization of Single-Walled Carbon Nanotubes in Ionic Liquids

Single walled carbon nanotubes (SWNTs) are exfoliated and functionalized predominantly as individuals by grinding them for minutes at room temperature with aryldiazonium salts in the presence of ionic liquids (ILs) and K(2)CO(3). This constitutes an extremely rapid and mild green chemical functionalization process for obtaining the individualized nanotube structures. A number of ILs and various reaction conditions were surveyed. Raman, XPS, UV/vis/NIR spectroscopies, thermogravimetric analysis, and atomic force and transmission electron microscopies were used to characterize the products.

Preparation and nanoscopic internal structure of single-walled carbon nanotube-ionic liquid gel

As an effort to expand their applicability of both room temperature ionic liquid (RTIL) and single-walled carbon nanotube (SWNT), we prepared a gel-like paste using imidazolium-based ionic liquid (1-n-butyl-3-methylimidazolium tetrafluoroborate; [Bmim] BF 4) and SWNT, and investigated their internal structure and viscoelastic characteristics. The suspension containing 1 wt% of SWNT was prepared via grinding it in an agate mortar. A black paste (gel) was then obtained from its centrifugation. Rheological properties of a purified SWNT- ionic liquid ([Bmim] BF 4) gel were measured using a rotational rheometer equipped with a parallel plate geometry, and then compared with those of unpurified SWNT-ionic liquid gel from both steady shear and oscillatory shear mode tests. We also examined their effects of a well-dispersed SWNT in a suspending medium on rheological properties, resulting in gel-state even at a very low filler concentration due to the nano-dimension of SWNT and its interaction with a novel ionic liquid. From this study, it is found that the characteristic rheological behaviors, such as high shear thinning, dynamic yield stress, and frequency independent dynamic behavior, not only support the gel formation due to the uniform dispersion of SWNT in the ionic liquid medium, but also explain the formation of network structure induced by a strong interaction between ionic liquid and SWNT. In addition, we also observed that such a gel structure was followed by a shear induced secondary structure in a high shear rate region.

Selective detection of dopamine in the presence of ascorbic acid and uric acid by a carbon nanotubes-ionic liquid gel modified electrode

The electrochemistry of dopamine (DA) was studied by cyclic voltammetry at a glassy carbon electrode modified by a gel containing multi-walled carbon nanotubes (MWNTs) and room-temperature ionic liquid of 1-octyl-3-methylimidazolium hexafluorophosphate (OMIMPF 6). The thickness of gel on the surface of the electrode has to be controlled carefully because the charging currents increase with the modified layer being thicker. The anodic peaks of DA, ascorbic acid (AA) and uric acid (UA) in their mixture can be well separated since the peak potential of AA is shifted to more negative values, while that of UA is shifted to more positive values due to the modified electrode. At pH 7.08 the three peaks are separated ca. 0.20 and 0.15 V, respectively; hence DA can be determined in the presence of UA and more than 100 times excess of AA. Under optimum conditions linear calibration graphs were obtained over the DA concentration range 1.0 × 10 −6 to 1.0 × 10 −4 M. The detection limit of the current technique was found to be 1.0 × 10 −7 M based on the signal-to-noise ratio of 3. The modified electrode has been successfully applied for the assay of DA in human blood serum. This work provides a simple and easy approach to selectively detect dopamine in the presence of ascorbic acid and uric acid.