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1.
Vibha Saxena Vinay Shirodkar Rajiv Prakash 《Applied biochemistry and biotechnology》2001,96(1-3):63-69
A device has been developed for the measurement of copper(II) ions (Cu++) in aqueous medium. The device reported here is an electrochemical transistor that consists of two platinum electrodes separated
by 100-μm spacing and bridged with an anodically grown polycarbazole film. The undoped polycarbazole film is observed to be
highly selective for the Cu(II) ions. In a completed device, the conductivity of the polycarbazole film changes on addition
of Cu (II)ions. This change in conductivity is attributed to the conformational changes in the polymer phase on occupation
of the Cu(II) ions, without affecting electron/proton transfer. The device turns on by adding 2.5×10−6
M Cu(II) ions and reaches a saturation region above a concentration of 10−4
M Cu(II) ions. In this concentration range, the plot of I
D
vs log[Cu(II)] is linear. The selectivity of the device for other metal ions such as Cu(I), Co(II), Fe(II), Fe(III), Zn(II),
and Pb(II) is also studied. 相似文献
2.
Vibha Saxena Vinay Shirodkar Rajiv Prakash 《Journal of Solid State Electrochemistry》2000,4(4):234-236
A device has been developed for the measurement of copper(II) ions (Cu2+) in aqueous medium. The device reported here is an electrochemical transistor which consists of two platinum electrodes separated
by 100 μm spacing and bridged with an anodically grown film of polycarbazole. Polycarbazole film (undoped form) is observed
to be highly selective for the Cu(II) ions. In a completed device, the conductivity of the polycarbazole film changes on addition
of Cu(II) ions. The change in conductivity is attributed to the conformational changes in the polymer phase on occupation
of the Cu(II) ions, without affecting electron/proton transfer. The device turns on by adding 2.5 × 10−6 M Cu(II) ions and reaches a saturation region beyond 10−4 M Cu(II) ion concentrations. In the above concentration range, the device response [I
D vs. log Cu(II) ion concentration] is linear. The selectivity of the device for other metal ions such as Cu(I), Ni(II), Co(II),
Fe(II), Fe(III), Zn(II) and Pb(II) is also studied.
Received: 6 April 1999 / Accepted: 20 August 1999 相似文献
3.
A new design of conductometric chemical sensors based on conducting polymers as chemosensitive elements was suggested. The sensor includes six electrodes. Four inner electrodes coated by chemosensitive polymer are used for simultaneous two- and four-point resistance measurements thus providing information on the bulk polymer resistance and on the resistance of the polymer/electrode contacts. Two outer electrodes wired to inner electrodes by polymeric electrolyte are used for electrical control of redox state of the chemosensitive polymer. The outer electrodes are connected to potentiostat as reference and counter electrodes. It allows us to control redox state of the inner (working) electrodes. This new measurement configuration, resembling chemosensitive electrochemical transistors, provides an internal test of the sensor integrity and an electrically driven sensor regeneration. It was tested as a sensor for the detection of nitrogen dioxide. Polythiophene or polyaniline was used as receptors. Cyclic voltammograms of these polymers on the sensor surface measured in air atmosphere were very similar to that measured in aqueous electrolyte. A control of conductivity of these chemosensitive polymers by electrical potential applied vs. incorporated reference electrode was demonstrated. This effect was used for the regeneration of the chemosensitive material after exposure to nitrogen dioxide: in comparison to usual chemiresistors displaying an irreversible behavior in such test even in the time scale of hours, a completely reversible sensor regeneration within few minutes was observed. 相似文献
4.
Guangming Nie Yan Zhang Jingkun Xu Shusheng Zhang 《Journal of Electroanalytical Chemistry》2008,622(1):121-127
High-quality free-standing poly(5-methoxyindole) (P5MIn) films were synthesized electrochemically by direct anodic oxidation of 5-methoxyindole (5MIn) in boron trifluoride diethyl etherate (BFEE). P5MIn films obtained from this medium showed good electrochemical behavior and good thermal stability with a conductivity of 0.12 S cm−1. P5MIn films were insoluble in water, acetone and tetrahydrofuran. The structure of the polymer was studied by UV–visible spectroscopy and FT-IR spectroscopy, which indicated that the polymerization occurred at C(2) and C(3) position. Fluorescent spectral studies indicate that solid P5MIn film is a good blue emitter. Thermal stability of P5MIn film is higher than poly(5-methylindole) and poly(5-chloroindole) obtained from BFEE. To the best of our knowledge, this is the first report on the electrosyntheses of free-standing P5MIn films. 相似文献
5.
Polyindole dispersions consisting of 20–30-nm-sized nanoparticles are prepared by chemical oxidation with ferric chloride using sodium dodecyl sulphate, poly(vinyl alcohol) and poly(vinyl acetate) as steric stabilizers. Pure acetonitrile and acetonitrile–water mixtures are used as solvents. The particle size depended on the concentrations of monomer and the steric stabilizer. The dispersions are characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform IR spectroscopy, thermal analysis and cyclic voltammetry techniques. 相似文献
6.
Aniline and pyrrole have been oxidized with ammonium peroxydisulfate in aqueous solutions, in the presence of equimolar quantities of hydrochloric acid. The oxidation of pyrrole was faster; the induction period typical of aniline oxidation was absent in the case of pyrrole. As the proportion of oxidant-to-monomer molar concentration increased up to 1.5, the yield increased in both cases. Similarities between the two oxidations are illustrated and discussed. The oxidant-to-monomer molar ratio 1.25 is proposed to be the optimum stoichiometry, in the accordance with the data published in the literature. The conductivities of the polymers prepared were only slightly dependent on the oxidant-to-monomer ratio in the range 0.3-1.5, and were of the order of 100 S cm−1 for polyaniline and ∼10−2-10−1 S cm−1 for polypyrrole. Outside this interval, the conductivity of both polymers was reduced. Polyaniline having conductivity ∼10 S cm−1 was produced in solutions of phosphoric acid of various concentrations. On the contrary, the conductivity of polypyrrole was reduced as the concentration of phosphoric acid became higher. The type of protonation is discussed with the help of FTIR spectra by analyzing the ammonium salts obtained after deprotonation. Sulfate or hydrogen sulfate anions produced from peroxydisulfate always constitute a part of the counter-ions. 相似文献
7.
A new and efficient synthetic route to hydroxymethylated-3,4-ethylenedioxylthiophene(EDOT-MeOH) was developed by a simple four-step sequence,and its global yield was approximately 41.06%.The poly(hydroxymethylated-3, 4-ethylenedioxylthiophene)(PEDOT-MeOH) film was electrosynthesized in aqueous sodium dodecylsulfate micellar solutions and characterized by different methods.The EDOT-MeOH possessed better water solubility,and lower onset oxidation potential than EDOT.The as-obtained PEDOT-MeOH film displayed good reversible redox activity,stability and capacitance properties in a monomer-free electrolyte,especially the good solubility of PEDOT-MeOH film in strong polar organic solvents such as dimethyl sulfoxide and tetrahydrofuran created a potential application in many different fields. Fluorescent spectra indicated that PEDOT-MeOH was a yellow-green-light-emitter with maximum emission at 568 nm.The as-formed PEDOT-MeOH film had good biocompatibility and was used for fabricating the electrochemical vitamin C biosensor.The proposed biosensor showed a linear range of 3×10-6 mol/L to 1.2×10-2 mol/L with the detection limit of 1μmol/L,a sensitivity of 95.6μA(mmol/L)-1 cm-2,and a current response time less than 10 s and a fairly good stability (The relative standard deviation was 0.43%for 20 successive assays,the proposed biosensor still retained 93.5%of bioactivity after 15 days storage.This result indicated that the prepared PEDOT-MeOH film as immobilization matrix of biologically-active species could be a promising candidate for the design and application of biosensor. 相似文献
8.
Dilute aqueous and non-aqueous solutions of bilirubin were exposed to gamma radiation to examine the effects of ionizing radiation on the concentrations of a specimen of this nature. The ionising radiation emanated from a (137)Cs source, and was applied to 5.2 x 10(-2) mmol L(-1) solutions of the unconjugated specimen in 0.05 mol L(-1) aqueous NaOH and chloroform. Depletion of bilirubin after exposure was common to both solvents. Complete degradation was accomplished with doses in excess of 100 Gy. In the case of NaOH, it was found that the presence of molecular oxygen contributed more efficiently to the degradation process, than irradiation in air. When the experimental conditions were changed to nitrogen, the degradation process was suppressed. The sole by-product of merit originating from the NaOH work was the short-wavelength isomer of biliverdin, at 330 nm. In the case of chloroform, the exclusive product of interest was characterised as the long-wavelength isomer of biliverdin that absorbs in the broad region commencing from about 620 nm. The non-aqueous study was conducted in the presence and absence of molecular oxygen, with no significant changes in the results. Optimum production of the isomers in question occurred at a gamma dose of about 80 Gy. The general species of interest were monitored spectrophotometrically, and the results were treated mathematically to facilitate evaluation of the data. Our work represents the development of a facile gamma-ray method for the exclusive production of specific isomers of biliverdin, which are useful components in biosynthetic research. 相似文献
9.
We have prepared polypyrrole both as a bulk powder and as a sterically stabilised colloidal dispersion in a noved non-aqueous solvent, 2-merhoxyethanol. The steric stabiliser utilised in the latter system was a poly(vinyl acetate) homopolymer. The electroactivity, morphology, thermal stability and chemical composition of these materials were characterised by d.c. conductivity measurememts, electron microscopy, thermogravimetry, FTIR and visible absorption spectroscopy and clemental microanalyses. The mass ratio of poly(vinyl acetate) to polypyrrole in the colloidal particles was determined indirectly by spectroscopic assay of the post-reaction supernatant solution for non-adsorbed stabiliser. 相似文献
10.
11.
High quality poly(5-cyanoindole) (P5CI) films were electrosynthesized by direct anodic oxidation of 5-cyanoindole on stainless steel sheet in the mixed electrolytes of boron trifluoride diethyl etherate (BFEE) and diethyl ether (EE) (by volume 1:1) + 0,05 mol L^-1 Bu4NBF4. The film formed can be peeled off the electrode into freestanding films, The addition of EE into BFEE can improve the solubility of monomer. P5CI films obtained from this medium showed excellent electrochemical behavior with conductivity of 10^-2 S cm^-1, Structural studies showed that the polymerization of 5-cyanoindole occurred at the 2,3 position. As-formed P5CI films were thoroughly soluble in strong polar organic solvent dimethyl sulfoxide (DMSO) while partly soluble in tetrahydrofuran (THF) or acetone. Fluorescence spectral studies indicated that P5CI was a good blue-ight emitter. 相似文献
12.
13.
以多层次聚苯胺颗粒为电极活性物质的超级电容器的电化学性能 总被引:21,自引:0,他引:21
以(NH4)2S2O8为氧化剂用化学氧化法合成了具有多层次结构的聚苯胺颗粒,其二次颗粒由一次颗粒集结而成,一次颗粒的粒径基本上在1 μm以下,一次颗粒由多层微小薄片叠合而成. 用这种聚苯胺为活性物质制成电极,以2 mol•L-1的H2SO4水溶液作电解液,组装成了聚苯胺电极超级电容器. 用循环伏安法、电化学阻抗谱和恒电流充放电技术测试了该超级电容器的电化学性能.在7 mA的充放电电流下,它的比能量可达6.35 Wh•kg-1,比功率可达132 W•kg-1,电极材料的比容量可达408 F•g-1. 在20 mA的充放电电流下,它的比能量可达4.39 Wh•kg-1,比功率可达328 W•kg-1,电极材料的比容量可达324 F•g-1. 在100次的充放电循环中,聚苯胺电极超级电容器的电容量没有下降,电荷充放电效率一直保持在95%左右. 相似文献
14.
Saeromi Chung Mahmood H. Akhtar A. Benboudiaf Deog‐Su Park Yoon‐Bo Shim 《Electroanalysis》2020,32(3):520-527
An electrochemical sensor based on the conducting polymer composite with a palladium complex (Pd(C2H4N2S2)2) was developed for the detection of serotonin and dopamine simultaneously in the breast cancer cell and human plasma samples. The proposed sensor was fabricated using the Pd(C2H4N2S2)2 complex‐anchored poly2,2 : 5,2‐terthiophene‐3‐(p‐benzoic acid) (pTBA) layer on the AuNPs decorated reduced graphene oxide (AuNPs@rGO) substrate, which revealed the enhanced anodic current of the target species. The sensor probe was characterized by electrochemical and surface analysis methods. The experimental parameters affecting the sensor performance were optimized, in terms of AuNPs@rGO concentration, the number of electropolymerization cycle for pTBA, immobilization time of Pd(C2H4N2S2)2, and pH. The dynamic ranges for serotonin and dopamine were obtained from 0.02 to 200 μM, and from 0.1 to 200 μM with the detection limit of 2.5, and 24.0 nM, respectively. The reliability of proposed sensor was evaluated using cancer cell lines for the clinical applications. 相似文献
15.
A series of coin-type lithium secondary batteries with polyaniline positive electrodes was developed and commercialized which might be not only the first practical polymer battery but also the first industrial application of conducting polymers. Performances of the commercialized batteries were described in detail in this paper. In order to achieve the development the most important thing was the optimization of molecular structure and molphology of multiguise polyaniline as the electrode material. According to the findings obtained during the development, polyaniline sheet was prepared substantially to be composed of imino-1,4-phenylene (IP) and the cation radical of IP (IP+) by the novel procedure, not to include quinoid configuration of polyaniline (NP) which was proved to be electrochemically inactive in non-aqueous systems. 相似文献
16.
《Arabian Journal of Chemistry》2020,13(7):6061-6071
Polyindole (PIn) has attracted extensive interest as promising energy storage materials owing to fairly good thermal stability, high redox activity and stability, however, it is challenging to prepare high-quality PIn in neutral solvents by electrochemical method. Herein, a simple route, based on MoS2 nanosheets as electrolytes, has been developed for the electrochemical preparation of PIn/MoS2 nanocomposite in acetonitrile solution. Due to the coordination interaction between indole and MoS2, the onset oxidation potential of indole in this medium was reduced to 0.5 V from 0.75 V determined in acetonitrile/LiClO4. The morphologies and structures of as-obtained PIn/MoS2 nanocomposite were characterized using SEM, TEM, XRD, Raman and XPS. The results of thermal analysis indicated that the PIn/MoS2 nanocomposite had an improved thermal stability relative to PIn and MoS2 nanosheets. Moreover, the specific capacitance of PIn/MoS2 nanocomposite was 8.3 times higher than that of PIn prepared acetonitrile/LiClO4. To the best of our knowledge, this is the first report on the high-efficiency electrodeposition of PIn/MoS2 nanocomposite in MoS2-based acetonitrile solution, which will be a promising candidate as a high efficient electrode material in the application of supercapacitors. 相似文献
17.
Well-known as a hazardous compound, nitrite constitute a real threat to the public health. So, there is a pressing need to detect and quantify them in different matrix. Even though conventional analytical methods can be used to address this issue, electrochemistry allows a fast, sensitive, and efficient analysis. Conducting polymers continue to raise great interest among scientific communities due to their properties. Moreover, their combination with carbon nanomaterials, or metallic nanoparticles improves their properties, and provides great results. In this paper, we will focus on some revealing works devoted to the electrochemical detection of nitrite using this kind of materials. 相似文献
18.
B. J. Eastwood P. A. Christensen R. D. Armstrong N. R. Bates 《Journal of Solid State Electrochemistry》1999,3(4):179-186
The suitability of a polymeric composite material for use as part of an anode structure in a cathodic protection system has
been examined. The composite material was a conductive blend (volume resistivity typically 1.5 Ω cm) of carbon black in a
polyethylene binder. A long operational lifetime for the material demands that the rate of carbon loss must be low. In the
work reported here, electrochemical and in situ analytical techniques were employed to characterise the performance of the material over a wide range of anodic current densities
in a variety of aqueous electrolytes. The predominant anodic electrochemical reaction on the polymeric material is CO2 formation in acid and neutral solutions, which causes loss of carbon from the surface and the development of a non-conducting
layer of polyethylene. The characteristics of the reaction suggest that it occurs via the discharge of H2O. In alkaline pH, however, the anodic reactions are more complex. A high OH− concentration (pH 12 or higher) favours the formation of oxygen rather than CO2, particularly at low anodic potentials. The presence of CO3
2− in the electrolyte catalyses the evolution of oxygen at pH values as low as 9. The electrochemical formation of oxygen always
occurs in parallel with the generation of some humic acid in the solution.
Received: 23 July 1998 / Accepted: 17 November 1998 相似文献
19.
The electrochemical double layer between Cu(111) electrodes and aqueous electrolytes (F− and SO2−4 at various pH values) was studied by means of linear scan voltammetry and ac impedance measurements. It is found that electrochemisorption of oxygen species proceeds on the Cu(111) surface in the potential regions more negative than the electrodissolution potential of copper. The adsorption-desorption kinetics are analysed; the anodic and cathodic symmetry coefficients are found to be equal (α = β = 0.3), and the standard rate constant is k° = 4 × 10−10cm s−1. 相似文献
20.
M. Elizabeth Welch Thomas Doublet Christophe Bernard George G. Malliaras Christopher K. Ober 《Journal of polymer science. Part A, Polymer chemistry》2015,53(2):372-377
Recently, there has been significant research in the area of organic electrochemical transistors (OECTs) because of their superior aptitude of chemical and biological sensing. Here it is shown for the first time the incorporation of polymer brushes to a transistor. Polymer brushes were chosen for their biocompatible properties and their ability to covalently tether enzymes and other biomolecules to different surfaces. OECTs were fabricated from the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate), PEDOT:PSS, and polymerized from the surface a mixed polymer brush of poly(glycidyl methacrylate) and poly(2-hydroxyethyl methacrylate). The brushes were functionalized with glucose oxidase and measured in terms of electrical performance and long-term stability. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 372–377 相似文献