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Electrochemical Characteristics (electrochemical + characteristic)
Selected AbstractsElectrochemical Characteristics of Mediated Laccase-Catalysis and Electrochemical Detection of Environmental PollutantsELECTROANALYSIS, Issue 8 2008Ying Liu Abstract Laccase has been immobilized on the carbon nanotubes modified glassy carbon electrode surface by adsorption. As-prepared laccase retains good electrocatalytic activity to oxygen reduction by using 2,2,-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) as the mediator. It can be used as a biosensor for the determination of catechol with broad linear range. Especially, azide, one of inhibitors of laccase, shows sensitive inhibition to catalytic activity of the laccase modified electrode. In addition, the inhibition by fluoride ions has also been studied. These demonstrate that the as-prepared electrode can be used to detect halide and some the toxic pollutants, e.g., catechol and azide based on catalytic or inhibition reaction of laccase. The simple preparation procedure makes the system can be developed as non-inhibition or inhibition biosensor. [source] Synthesis and Electrochemical Characteristics of Li0.7[Ni1/6Mn5/6]O2 Cathode Materials.CHEMINFORM, Issue 51 2002K. S. Park Abstract For Abstract see ChemInform Abstract in Full Text. [source] Crystallographic and Electrochemical Characteristics of La0.7Mg0.3Ni5.0,x(Al0.5Mo0.5)x Hydrogen-Storage Alloys,CHEMPHYSCHEM, Issue 3 2005Xin Bo Zhang Dr. Abstract The structure, hydrogen-storage property and electrochemical characteristics of La0.7Mg0.3Ni5.0,x(Al0.5Mo0.5)x(x=0,0.8) hydrogen-storage alloys have been studied systematically. X-ray diffraction Rietveld analysis shows that all the alloys consist of an La(La,Mg)2Ni9 phase and an LaNi5 phase. The pressure,composition isotherms indicate that the hydrogen-storage capacity first increases and then decreases with increasing x, and the equilibrium pressure decreases with increasing x. Electrochemical measurements show that the maximum discharge capacity and the exchange-current density of the alloy electrodes increase as x increases from 0 to 0.6 and then decrease when x increases further from 0.6 to 0.8. Moreover, the low-temperature dischargeability of the alloy electrodes increases monotonically with increasing x in the alloys. [source] Pulsed Amperometric Detection of Histamine at Glassy Carbon Electrodes Modified with Gold NanoparticlesELECTROANALYSIS, Issue 4 2005V. Carralero Abstract Gold nanocrystal-modified glassy carbon electrodes (nAu-GCE) were prepared and used for the determination of histamine by flow injection and high performance liquid chromatography using pulsed amperometric detection (PAD) as the detection mode. Experimental variables involved in the electrodeposition process of gold from a HAuCl4 solution were optimized. A catalytic enhancement of the histamine voltammetric response was observed at the nAu-GCE when compared with that obtained at a conventional Au disk electrode, as a consequence of the microdispersion of gold nanocrystals on the GC substrate. The morphological and electrochemical characteristics of the nAu-GCE were evaluated by SEM and cyclic voltammetry. PAD using a very simple potential waveform consisting of an anodic potential (+700,mV for 500,ms) and a cathodic potential (,300,mV for 30,ms), was used to avoid the electrode surface fouling when histamine was detected under flowing conditions. Flow injection amperometric responses showed much higher Ip values and signal-to-noise ratios at the nAu-GCE than at a conventional gold disk electrode. A limit of detection of 6×10,7,mol L,1 histamine was obtained. HPLC-PAD at the nAu-GCE was used for the determination of histamine in the presence of other biogenic amines and indole. Histamine was determined in sardine samples spiked at a 50,,g g,1 concentration level, with good results. Furthermore, the chromatographic PAD method was also used for monitoring the formation of histamine during the decomposition process of sardine samples. [source] Synthesis and properties of nitrogen-linked poly(2,7-carbazole)s as hole-transport material for organic light emitting diodesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2009Tsuyoshi Michinobu Abstract A novel class of carbazole polymers, nitrogen-linked poly(2,7-carbazole)s, was synthesized by polycondensation between two bifunctional monomers using the palladium-catalyzed amination reaction. The polymers were characterized by 1H NMR, Infrared, Gel permeation chromatography, and MALDI-TOF MS and it was revealed that the combination of the monomer structures is important for producing high molecular weight polymers. Thermal analysis indicated a good thermal stability with high glass transition temperatures, e.g., 138 °C for the higher molecular weight polymer P2. To pursue the application possibilities of these polymers, their optical properties and energy levels were investigated by UV-Vis absorption and fluorescence spectra as well as their electrochemical characteristics. Although the blue light emission was indeed observed for all polymers in solution, the quantum yields were very low and the solid films were not fluorescent. On the other hand, the HOMO levels of the polymers estimated from the onset potentials for the first oxidation in the solid thin films were relatively high in the range of ,5.12 to ,5.20 eV. Therefore, light emitting diodes employing these polymers as a hole-transport layer and iridium(III) complex as a triplet emitter were fabricated. The device of the nitrogen-linked poly(2,7-carbazole) P3 with p,p,-biphenyl spacer, which has a higher HOMO level and a higher molecular weight, showed a much better performance than the device of P2 with m -phenylene spacer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3880,3891, 2009 [source] Modelling and parameter comparison of equivalent circuits on the basis of impedance measurements of stainless steelsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 4 2006M. Slemnik Abstract In our former work [1] we have discussed the impedance of differently heat treated steels X20Cr13 in 0.1 M H2SO4, undergoing an active passive transition. Impedance spectra were interpreted in terms of a model by Armstrong [2, 3], describing the electrochemical reaction at interfaces with adsorbed intermediates. The present work was performed in order to study this phenomenon in more detail, with computer simulations of a new created and more convenient equivalent circuit in comparison with the former model. Computer simulations of equivalent circuits were also made in the region of passivity which was also continuation of our earlier work [4]. In this sense the entire study for these steels was completed by collating distinctive parameter values, demonstrating electrochemical characteristics of steel X20Cr13, undergoing different heat treatments in the active-passive and passive region. [source] Preparation of lithium indium oxide via a rheological phase route and its electrochemical characteristics in LiOH and Li2SO4 solutionsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2010Guo-Qing Zhang Abstract Submicrometer-sized lithium indium oxide (LiInO2) powder via a rheological phase method using trilithium citrate tetra hydrate (C6H5Li3O7,·,4H2O) and indium oxide (In2O3) has been prepared in this work for the first time. The optimal pyrolyzing temperature range to prepare crystalline LiInO2 is between 650 and 900,°C, which was confirmed by thermal gravimetric and differential thermogravimetric analysis of the precursor and X-ray diffraction analysis. The pure phase LiInO2 sample obtained has a uniform particle morphology and submicrosize, which was observed by scanning electron microscopy. The electrochemical studies show that a new pair of cathodic and anodic peaks at 0.23 and 0.38,V (vs. saturated calomel electrode) was obviously observed from the cyclic voltammetry curve of LiInO2 in 1,M LiOH solution, indicating a battery characteristic of the material in this electrolyte. While in 1,M Li2SO4 solution, the sample presents a supercapacitive characteristic within the same potential range. The reasons for different electrochemical behaviors in these two electrolytes can be attributed to the fact that the reaction of lithium ion insertion/extraction into/out of a LiInO2 electrode takes place in the bulk material in LiOH electrolyte solution, whereas it takes place on the electrode/electrolyte interface for Li2SO4 electrolyte case. [source] Ethanol-tolerant Pt-alloy cathodes for direct ethanol fuel cell (DEFC) applicationsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009F. J. Rodríguez Varela Abstract The electroactivity of Pt1Co1(a/o)/C and Pt3Cr1(a/o)/C for the oxygen reduction reaction (ORR) in ethanol-containing medium was studied. It was found that these cathodes present a high tolerance to this alcohol. The onset potential of the ORR decreased at 14 and 12 mV in the presence of 0.5 M ethanol on Pt1Co1/C and Pt3Cr1/C, respectively. The tolerance of the Pt alloys is one order of magnitude higher than that shown by Pt-alone catalysts in previous works. Exceptionally, the Pt1Co1/C alloy maintained a very important electrocatalytic activity, i.e. a very small variation in current density at 400 mV in electrochemical cell measurements and improved performances in a direct ethanol fuel cell (DEFC). The current densities obtained from the DEFC equipped with a 10% Pt1Co1/C cathode were similar to those obtained when 20% Pt3Cr1/C was used. However, a higher performance in terms of Pt content was shown by PtCo/C. These electrochemical characteristics indicate the advantage of using PtCo alloys as cathodes in DEFCs. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Crystallographic and Electrochemical Characteristics of La0.7Mg0.3Ni5.0,x(Al0.5Mo0.5)x Hydrogen-Storage Alloys,CHEMPHYSCHEM, Issue 3 2005Xin Bo Zhang Dr. Abstract The structure, hydrogen-storage property and electrochemical characteristics of La0.7Mg0.3Ni5.0,x(Al0.5Mo0.5)x(x=0,0.8) hydrogen-storage alloys have been studied systematically. X-ray diffraction Rietveld analysis shows that all the alloys consist of an La(La,Mg)2Ni9 phase and an LaNi5 phase. The pressure,composition isotherms indicate that the hydrogen-storage capacity first increases and then decreases with increasing x, and the equilibrium pressure decreases with increasing x. Electrochemical measurements show that the maximum discharge capacity and the exchange-current density of the alloy electrodes increase as x increases from 0 to 0.6 and then decrease when x increases further from 0.6 to 0.8. Moreover, the low-temperature dischargeability of the alloy electrodes increases monotonically with increasing x in the alloys. [source] Electrochemical Preparation and Characterization of Lanthanum Hexacyanoferrate Modified ElectrodeCHINESE JOURNAL OF CHEMISTRY, Issue 2 2005Wu Ping Abstract An electroactive polynuclear inorganic compound of rare earth metal hexacyanoferrate, lanthanum hexacyanoferrate (LaHCF), was prepared by electrochemical deposition on the surface of a glassy carbon electrode with a potential cycling procedure. The cyclic voltammogram of LaHCF exhibits a pair of well-defined redox peaks with the formal potential of 208 mV (vs. SCE) at a scan rate of 100 mV/s in 0.2 mol/L NaCl solution and the redox peak currents increase linearly with the square root of the scan rate up to 1000 mV/s. The effects of the concentration of supporting electrolyte on the electrochemical characteristics of LaHCF were studied by voltammetry. LaHCF was also characterizated by scanning electron microscope (SEM), FTIR and XPS techniques. [source] | |||||||||||||