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Electrochemical Cell (electrochemical + cell)
Kinds of Electrochemical Cell Selected AbstractsOptimization of a Composite Working Electrode for a New Family of Electrochemical Cell for NO DecompositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2003Kazuyuki Matsuda The electrochemical properties of a composite (NiO)x,(yttria-stabilized zirconia (YSZ))1,x working electrode for a new type of electrochemical cell for NO decomposition in the presence of excess oxygen are investigated. It is shown that the dependence of the NO conversion on the value of the current passed through the electrochemical cell with a nanoporous (NiO)x,(YSZ)1,x working electrode is linear and that the value of current efficiency depends on the NO and O2 gas concentrations only (,= [NO] /([NO] + 2[O2]). The optimum NiO addition (35% by volume) to the YSZ resulted in a decrease of the cell operating voltage and, as a result, in a decrease in the electrical power required for NO decomposition. The observed high performance of the composite working electrode at this composition is consistent with the effective medium percolation theory, which predicts the ambipolar transport behavior of the composite mixed ionic,electronic (YSZ,NiO) conductors as a function of the volume fraction of each of the randomly distributed constituent phases. [source] Positively Charged Iridium(III) Triazole Derivatives as Blue Emitters for Light-Emitting Electrochemical CellsADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Mathias Mydlak Abstract Cationic blue-emitting complexes with (2,4-difluoro)phenylpyridine and different 1,2,3-triazole ligands are synthesized with different counterions. The influence of the substituents on the triazole ligand is investigated as well as the influence of the counterions. The substituents do not change the emission energy but, in some cases, slightly modify the excited-state lifetimes and the emission quantum yields. The excited-state lifetimes, in apolar solvents, are slightly dependent on the nature of the counterion. A crystal structure of one of the compounds confirms the geometry and symmetry postulated on the basis of the other spectroscopic data. Light-emitting electrochemical cell devices are prepared and the recorded emission is the bluest with the fastest response time ever reported for iridium complexes. [source] Efficient and Long-Living Light-Emitting Electrochemical CellsADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Rubén D. Costa Abstract Three new heteroleptic iridium complexes that combine two approaches, one leading to a high stability and the other yielding a high luminescence efficiency, are presented. All complexes contain a phenyl group at the 6-position of the neutral bpy ligand, which holds an additional, increasingly bulky substituent on the 4-position. The phenyl group allows for intramolecular ,,, stacking, which renders the complex more stable and yields long-living light-emitting electrochemical cells (LECs). The additional substituent increases the intersite distance between the cations in the film, reducing the quenching of the excitons, and should improve the efficiency of the LECs. Density functional theory calculations indicate that the three complexes have the desired ,,, intramolecular interactions between the pendant phenyl ring of the bpy ligand and the phenyl ring of one of the ppy ligands in the ground and the excited states. The photoluminescence quantum efficiency of concentrated films of the complexes improves with the increasing size of the bulky groups indicating that the adopted strategy for improving the efficiency is successful. Indeed, LEC devices employing these complexes as the primary active component show shorter turn-on times, higher efficiencies and luminances, and, surprisingly, also demonstrate longer device stabilities. [source] Archetype Cationic Iridium Complexes and Their Use in Solid-State Light-Emitting Electrochemical CellsADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Rubén D. Costa Abstract The archetype ionic transition-metal complexes (iTMCs) [Ir(ppy)2(bpy)][PF6] and [Ir(ppy)2(phen)][PF6], where Hppy,=,2-phenylpyridine, bpy,=,2,2,-bipyridine, and phen,=,1,10-phenanthroline, are used as the primary active components in light-emitting electrochemical cells (LECs). Solution and solid-state photophysical properties are reported for both complexes and are interpreted with the help of density functional theory calculations. LEC devices based on these archetype complexes exhibit long turn-on times (70 and 160,h, respectively) and low external quantum efficiencies (,2%) when the complex is used as a pure film. The long turn-on times are attributed to the low mobility of the counterions. The performance of the devices dramatically improves when small amounts of ionic liquids (ILs) are added to the Ir-iTMC: the turn-on time improves drastically (from hours to minutes) and the device current and power efficiency increase by almost one order of magnitude. However, the improvement of the turn-on time is unfortunately accompanied by a decrease in the stability of the device from 700 h to a few hours. After a careful study of the Ir-iTMC:IL molar ratios, an optimum between turn-on time and stability is found at a ratio of 4:1. The performance of the optimized devices using these rather simple complexes is among the best reported to date. This holds great promise for devices that use specially-designed iTMCs and demonstrates the prospect for LECs as low-cost light sources. [source] Toward Highly Efficient Solid-State White Light-Emitting Electrochemical Cells: Blue-Green to Red Emitting Cationic Iridium Complexes with Imidazole-Type Ancillary LigandsADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Lei He Abstract Using imidazole-type ancillary ligands, a new class of cationic iridium complexes (1,6) is prepared, and photophysical and electrochemical studies and theoretical calculations are performed. Compared with the widely used bpy (2,2,-bipyridine)-type ancillary ligands, imidazole-type ancillary ligands can be prepared and modified with ease, and are capable of blueshifting the emission spectra of cationic iridium complexes. By tuning the conjugation length of the ancillary ligands, blue-green to red emitting cationic iridium complexes are obtained. Single-layer light-emitting electrochemical cells (LECs) based on cationic iridium complexes show blue-green to red electroluminescence. High efficiencies of 8.4, 18.6, and 13.2,cd A,1 are achieved for the blue-green-emitting, yellow-emitting, and orange-emitting devices, respectively. By doping the red-emitting complex into the blue-green LEC, white LECs are realized, which give warm-white light with Commission Internationale de L'Eclairage (CIE) coordinates of (0.42, 0.44) and color-rendering indexes (CRI) of up to 81. The peak external quantum efficiency, current efficiency, and power efficiency of the white LECs reach 5.2%, 11.2,cd,A,1, and 10,lm,W,1, respectively, which are the highest for white LECs reported so far, and indicate the great potential for the use of these cationic iridium complexes in white LECs. [source] Light-Emitting Electrochemical Cells: The Design and Realization of Flexible, Long-Lived Light-Emitting Electrochemical Cells (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Mater. A highly functional flexible light-emitting electrochemical cell during operation is depicted in this cover image. By optimizing the composition of the active material and by employing an appropriate operation protocol, as described by Fang et al. on page 2671, more than one month of uninterrupted operation at significant brightness (>100 cd,2 ) and relatively high power conversion efficiency (2 lm W,1 for orange-red emission) is realized. [source] The Design and Realization of Flexible, Long-Lived Light-Emitting Electrochemical CellsADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Junfeng Fang Abstract Polymer light-emitting electrochemical cells (LECs) offer an attractive opportunity for low-cost production of functional devices in flexible and large-area configurations, but the critical drawback in comparison to competing light-emission technologies is a limited operational lifetime. Here, it is demonstrated that it is possible to improve the lifetime by straightforward and motivated means from a typical value of a few hours to more than one month of uninterrupted operation at significant brightness (>100,cd m,2) and relatively high power conversion efficiency (2 lm W,1 for orange-red emission). Specifically, by optimizing the composition of the active material and by employing an appropriate operational protocol, a desired doping structure is designed and detrimental chemical and electrochemical side reactions are identified and minimized. Moreover, the first functional flexible LEC with a similar promising device performance is demonstrated. [source] New Approach Toward Fast Response Light-Emitting Electrochemical Cells Based on Neutral Iridium Complexes via Cation TransportADVANCED FUNCTIONAL MATERIALS, Issue 5 2009Tae-Hyuk Kwon Abstract Here, a new method is presented to increase the turn-on time and stability of light-emitting electrochemical cells (LECs). To this end, a neutral iridium complex (5) containing a pendant Na+ ion that is generally known to have a faster mobility in the solid film than bulky anions is introduced, instead of the classic ionic transition metal complex (iTMC) with counter anion (7). Synthesis, photophysical and electrochemical studies of these complexes are reported. In the device configuration of ITO/5 or 7+PEO (polyethylene oxide) (100,110,nm)/Au, as the voltage increases, complex 5 emits red light at ,3.6,V while complex 7 appears at ,5.6,V, although their electrochemical and photophysical gap are similar. Furthermore, at constant voltage, ,3,V, the turn-on time of complex 5 was less than 0.5,min, which is a 60-fold faster turn-on time compared to the iTMC (7) with PF6,. These results are presumably due to the faster delivery of the Na+ ions to the electrode compared to PF6, ions. Also, the device lifetime of complex 5 exhibits a six-fold increase in stability and a three-fold shorter time to reach maximum brightness at constant bias compared to the device made with complex 7. [source] Long-Lifetime Polymer Light-Emitting Electrochemical Cells Fabricated with Crosslinked Hole-Transport LayersADVANCED MATERIALS, Issue 19 2009Yan Shao By inserting a crosslinkable hole-transport layer as the buffer layer between the single-phase polymer active layer and the anode of this new type of polymer light-emitting electrochemical cells (PLECs), the interface properties are improved and the PLECs can be operated with enhanced stability. [source] System Ln,Fe,O (Ln: Ho, Er): Thermodynamic Properties of Ternary Oxides Using Differential Scanning Calorimetry and Solid-State Electrochemical Cells.CHEMINFORM, Issue 37 2006S. C. Parida Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Simultaneous Determination of Gibbs Free Energies of Formation of Sr2RhO4(s) and Sr4RhO6(s) Using Solid-State Electrochemical Cells.CHEMINFORM, Issue 1 2005Aparna Banerjee No abstract is available for this article. [source] Quasi-two-dimensional electrodeposition growth of Pb0.5Sn0.5 alloyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2006Bin Sun Abstract Electrodeposition of Pb0.5Sn0.5 alloy is carried out in a quasi-2D electrochemical cell. As the growth proceeds the morphologies of the deposits transit from cake-like to branched and finally to the compact morphology. We show that these morphological transitions arise from the changes in the transport mechanisms of the ions in the electrolyte cell. In addition, it is found that the current density on the growth interface can vary spontaneously due to the irregular shape of the deposit and the generation of hydrogen gas. It causes the formation of the complex microstructure with non-uniform composition. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrochemically Induced Iron Release of Adsorbed Horse Spleen Ferritin: Quantitation of Iron Using Long Optical Path Length Thin-Layer SpectroelectrochemistryELECTROANALYSIS, Issue 23 2007Abstract In this work, long optical path length thin-layer electrochemical cell was constructed using indium-tin oxide on glass as the electrode material. Iron release from ferritin adsorbed on the electrode was induced by applying a negative potential sweep in the presence of 1,10-phenanthroline. The usefulness of spectroelectrochemistry as a means of determining the quantity of iron released from an adsorbed layer of ferritin is demonstrated. [source] Gold Nanoparticle-Based Mediatorless Biosensor Prepared on Microporous ElectrodeELECTROANALYSIS, Issue 3 2006Fenghua Zhang Abstract A mediatorless biosensor was fabricated with a double-sided microporous gold electrode by successively immobilizing a mixed self-assembled monolayer (SAM) comprising carboxylic-acid- and thiol-terminated thiolate (dl -thiorphan and 1,8-octanedithiol), glucose oxidase (GOx) and finally gold nanoparticle (Au NP) on one working side. The double-sided microporous gold electrodes were formed by plasma sputtering of gold on a porous nylon substrate, yielding a face-to-face type two-electrode electrochemical cell. While the straight chain molecule 1,8-octanedithiol forms a dense insulating monolayer, the side armed dl -thiorphan forms a low density layer for the diffusion of redox couples to the electrode surface. The mixed SAM not only provided the linking functional groups for both enzyme and Au NP but also resulted in the appropriately spaced monolayer for direct electron tansfer (ET) process from the center of the redox enzyme to the electrode surface. After covalently immobilizing GOx onto the carboxylic-acid-terminated monolayer, Au NP was easily immobilized to both enzyme and nearby thiols by simple dispensing of the colloidal gold solution. It was observed that the resulting amperometric biosensor exhibited quantitatively the same response to glucose in the presence and in the absence of dissolved oxygen, which evidence that the Au NPs immobilized on and around the GOx promote direct ET from the enzymes to the electrode, assuming the role of a common redox mediator. [source] Comparison of Different Strategies on DNA Chip Fabrication and DNA-Sensing: Optical and Electrochemical ApproachesELECTROANALYSIS, Issue 22 2005Sabine Szunerits Abstract New strategies for the construction of DNA chips and the detection of DNA hybridization will be discussed in this review. The focus will be on the use of polypyrrole as a linker between a substrate and oligonucleotide probes. The modification step is based on the electrochemical copolymerization of pyrrole and oligonucleotides bearing a pyrrole group on its 5, end. This strategy was employed for the immobilization of oligonucleotides on millimeter-sized electrodes, microelectrode arrays, as well as for the local structuring of homogeneous gold surfaces. Our approaches for the localized patterning of gold surfaces will be also discussed. Localized immobilization was achieved by using an electrospotting technique, where a micropipette served as an electrochemical cell where spot sizes with 800,,m diameters were fabricated. The use of a microcell using a Teflon covered metal needle with a cavity of 100,,m resulted in immobilized probe spots of 300,,m. Scanning electrochemical microscopy (SECM) was also used, and surface modifications of 100,,m were obtained depending on the experimental conditions. Different detection methods were employed for the reading of the hybridization event: fluorescence imaging, surface plasmon resonance imaging (SPRI), photocurrent measurements, and voltamperometric measurements using intercalators. Their advantages concerning the various immobilization strategies will also be discussed. [source] A Tubulin-Based Quantitative Assay for Taxol (Paclitaxel) with Enzyme Channeling SensingELECTROANALYSIS, Issue 8 2004Shin-ichiro Suye Abstract We report the development and characterization of a biosensor for sensitive and rapid determination of the anticancer agent Taxol (paclitaxel). The sensor is based on the interaction of Taxol with its receptor protein tubulin in conjunction with the separation-free immunosensor technique of enzyme channeling. The sensor system consisted of a three electrode electrochemical cell containing a graphite carbon electrode modified with glucose oxidase and tubulin as working electrode poised at +40,mV (vs. Ag/AgCl). Addition of Taxol, horseradish peroxidase labeled Taxol, glucose and potassium iodide to the cell generated a cathodic current response that was proportional to the concentration of Taxol in the range of 10 to 1,000,pM. [source] Ni(II)cyclam Catalyzed Reduction of CO2 , Towards a Voltammetric Sensor for the Gas PhaseELECTROANALYSIS, Issue 18 2003P. Jacquinot Abstract The detection of CO2 in the gas phase is possible in presence of oxygen with an amalgamated Au-poly(tetrafluoroethylene) gas diffusion electrode and an internal electrolyte solution containing Ni(II)cyclam. For concentrations between 0.1 to 1% the electrochemical cell has a sensitivity of 3.58 mA %,1 and the detection limit is 500,ppm. In preliminary experiments at rotating disk electrodes the optimum pH-range was found to be between 3.5 to 6 and a selectivity ratio of the catalyst for CO2/H+ of 5,:,1 could be determined. The relationship between reduction current and the square root of the angular speed is linear, indicating that the electrochemical process is limited by diffusion of CO2. Tl and Pb are presented as alternative electrode materials at which the Ni(II)cyclam catalyzed reduction of CO2 can be observed. Problems arise from fouling effects at the sensing electrode and a non-linearity of the calibration plot at higher concentrations. [source] Light-Emitting Electrochemical Cells: The Design and Realization of Flexible, Long-Lived Light-Emitting Electrochemical Cells (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Mater. A highly functional flexible light-emitting electrochemical cell during operation is depicted in this cover image. By optimizing the composition of the active material and by employing an appropriate operation protocol, as described by Fang et al. on page 2671, more than one month of uninterrupted operation at significant brightness (>100 cd,2 ) and relatively high power conversion efficiency (2 lm W,1 for orange-red emission) is realized. [source] Preparation of LiMn2O4 powders via spray pyrolysis and fluidized bed hybrid systemAICHE JOURNAL, Issue 7 2006Izumi Taniguchi Abstract A novel technique has been developed to directly produce fine ceramic powders from liquid solution using a spray pyrolysis and fluidized bed hybrid system. Using this technique, the preparation of lithium manganese oxides LiMn2O4, which are the most promising cathode materials for lithium-ion batteries, has been carried out for various superficial gas velocities U0 = 0.30-0.91 m/s, static bed heights Ls = 50-150 mm, and medium particle sizes dpm,g = 294-498 ,m. The resulting powders had spherical nanostructured particles that comprised primary particles with a few tens of nanometer in size, and they exhibited a pure cubic spinel structure without any impurities in the XRD patterns. Moreover, the as-prepared powders showed better crystallinity and smaller specific surface area than those by conventional spray pyrolysis. The effects of process parameters on powder properties, such as specific surface area and crystallinity, were investigated for a wide range of superficial gas velocities and static bed heights. An as-prepared sample was used as cathode active materials for lithium-ion batteries and the cell performance has been investigated. Test experiments in the electrochemical cell Li/1M LiClO4 in PC/LiMn2O4 demonstrated that the sample prepared by the present technique was superior to that by the conventional spray pyrolysis and solid-state reaction method. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Development of an electrochemical cell for efficient hydrogen production through the IS processAICHE JOURNAL, Issue 8 2004Mikihiro Nomura Abstract The Bunsen reaction (SO2 + I2 + 2H2O = H2SO4 + 2HI) was examined by an electrochemical cell featuring a cation-exchange membrane as the separator, using sulfuric acid dissolving sulfur dioxide as the anolyte and hydriodic acid dissolving iodine as the catholyte. In galvanostatic electrolysis, the molality of H2SO4 in the anolyte and that of HI in the catholyte were increased up to 17.8 and 14.9 mol kgH2O,1, respectively. These concentrations were far higher than those that were obtained by the Bunsen reaction carried out in the presence of a large amount of iodine (such as I2/HI = 4). I2 concentration after the concentration procedure was at I2/HI = 0.95, which is lower than the reported value. I2 is one of the recycling agents in the IS process. HI and H2SO4 were successfully concentrated under low I2 concentration. The concentration of HI agreed with the calculated value, based on the amount of electricity consumed, indicating high current efficiency. Heat/mass balance using this type of electrochemical cell through the IS process is discussed for evaluation of the reactor. The thermal efficiency to produce hydrogen was calculated at 42.1%, without heat recovery for electricity, by optimizing HI and H2SO4 concentrations after application of the electrochemical cell. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1991,1998, 2004 [source] Optimization of a Composite Working Electrode for a New Family of Electrochemical Cell for NO DecompositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2003Kazuyuki Matsuda The electrochemical properties of a composite (NiO)x,(yttria-stabilized zirconia (YSZ))1,x working electrode for a new type of electrochemical cell for NO decomposition in the presence of excess oxygen are investigated. It is shown that the dependence of the NO conversion on the value of the current passed through the electrochemical cell with a nanoporous (NiO)x,(YSZ)1,x working electrode is linear and that the value of current efficiency depends on the NO and O2 gas concentrations only (,= [NO] /([NO] + 2[O2]). The optimum NiO addition (35% by volume) to the YSZ resulted in a decrease of the cell operating voltage and, as a result, in a decrease in the electrical power required for NO decomposition. The observed high performance of the composite working electrode at this composition is consistent with the effective medium percolation theory, which predicts the ambipolar transport behavior of the composite mixed ionic,electronic (YSZ,NiO) conductors as a function of the volume fraction of each of the randomly distributed constituent phases. [source] The iR drop , well-known but often underestimated in electrochemical polarization measurements and corrosion testing,MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 6 2006W. Oelßner Abstract At first sight the problem of the iR drop and its compensation in electrochemical polarization measurements seems to have only minor significance, but it has actually troubled electrochemists and corrosion scientists for more than a hundred years. For reducing the iR drop in the electrochemical cell, its computation, experimental determination and numerical or automatic electronic compensation numerous scientific and experimental work has been carried out and appropriate suggestions were submitted. These efforts led to commercially available potentiostats with sophisticated facilities for automatic iR compensation. Nevertheless, to date these possibilities have been utilized with a certain hesitancy. Many users underestimate the iR drop, regarding it often merely as a marginal problem, which only has to be taken into account in experiments with very high currents or extremely low conductivity of the electrolyte. Furthermore, there are also doubts and prejudices regarding modern methods of iR compensation, resulting from previous unpleasant experiences or reports on failed experiments with inappropriate equipment or imperfect methods. Reduction or automatic compensation of the iR drop is necessary more frequently than generally assumed and also in most cases possible. On the other hand the application of the different methods is still not completely uncomplicated and requires special experimental experience and care. The aim of the present work is it therefore to give a comprehensive retrospective overview of the ohmic drop problem and the relevant activities to overcome it. [source] Voltage-induced morphological modifications in oocyte membranes containing exogenous K+ channels studied by electrochemical scanning force microscopyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 4 2008Andrea Alessandrini Abstract We report on a novel use of electrochemical scanning force microscopy (SFM) for the investigation of morphological modifications occurring in plasma membranes containing voltage-gated ion channels, on membrane potential variation. Membrane patches of Xenopus laevis oocytes microinjected with exogenous KAT1 cRNA, deposited by a stripping method at the surface of a derivatized gold film in inside-out configuration, have been imaged by SFM in an electrochemical cell. A potentiostat was used to maintain a desired potential drop across the membrane. Performing imaging at potential values corresponding to open (,120 mV) and closed (+20 mV) states for KAT1, morphological differences in localized sample zones were observed. Particularly, cross-shaped features involving a significant membrane portion appear around putative channel locations. The reported approach constitutes the first demonstration of an SPM-based experimental technique suitable to investigate the rearrangements occurring to the plasma membrane containing voltage-gated channels on transmembrane potential variation. Microsc. Res. Tech., 2008. © 2007 Wiley-Liss, Inc. [source] GaN-based Schottky diodes for hydrogen sensing in transformer oilPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006Peter Sandvik Abstract We report the demonstration of robust, GaN-based hydrogen sensors for use directly in transformer oil. These 1 mm2 Schottky diodes were immersed in a closed loop with Voltesso insulating oil for 21 months of continuous testing. They showed good reproducibility in response to hydrogen gases, while exposed to varying temperatures. We will briefly discuss the transformer monitoring application, the device design and fabrication process, and the sensor performance from 21-months of testing. Transfer functions from oil temperature and dissolved gas concentration have been quantified, and those will be briefly discussed. These new sensors offer a novel alternative to electrochemical cell-based sensors for various applications. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The adsorption of L-cysteine on Au(110) in ultra-high vacuum and electrochemical environmentsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2005G. E. Isted Abstract We have investigated the adsorption of L-cysteine (L-Cys) onto Au(110) in an electrochemical cell and under ultra-high vacuum (UHV) conditions using reflection anisotropy spectroscopy (RAS). The L-Cys saturated surfaces created by both deposition methods exhibit similar RA profiles which indicates a similar adsorption process. Our results are consistent with L-Cys binding to the Au(110) surface through a goldthiolate (Au-S) linkage. Heating the L-Cys saturated surface in UHV to 580 K results in the decomposition of the adsorbate and leaves behind a sulphur/Au surface composed of different structural domains. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electroinduced oxidative copolymerization of N -vinyl carbazole with methyl ethyl ketone formaldehyde resinPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2004s Ustamehmeto Abstract In this study, a novel procedure to obtain the non-crosslinked, photoconductive, white form of the linear copolymer of N -vinyl carbazole (NVCz) and methyl ethyl ketone formaldehyde resin (MEKF-R) is reported. A possible mechanism of copolymerization is suggested. The yield of the copolymer is increased almost 10 times by the addition of catalytic amounts of ceric ammonium nitrate as an oxidant during the electrochemical polymerization of NVCz in the presence of MEKF-R in a divided electrochemical cell. Since cerium(III) is readily oxidized to cerium(IV) at the anode, the concentration of cerium(IV) remained constant and the deposition of green poly(NVCz) can be prevented. Copyright © 2004 John Wiley & Sons, Ltd. [source] Degradation of tetracycline in aqueous medium by electrochemical methodASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Hui Zhang Abstract The degradation of tetracycline by anode oxidation with Ti/RuO2,IrO2 electrode was carried out in an electrochemical cell. The effect of operating conditions such as electrical current density, initial pH, antibiotic concentration, electrolyte concentration and hydroxyl radical scavenger on the oxidation of tetracycline was investigated. The results showed that the degradation of tetracycline followed apparent pseudo-first-order kinetics. The rate constant increased linearly with the current density, but the oxidation curves displayed the same dependence on the amount of the specific charge passed. The degradation rate decreased with the initial antibiotic concentration. Either initial pH or electrolyte concentration had little effect on the electrochemical oxidation of tetracycline. The presence of tert -butanol did not hinder the degradation rate, indicating the radical contribution to the oxidation of tetracycline could be neglected. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Orientation Ordering of Nanoparticle Ag/Co Cores Controlled by Electric and Magnetic FieldsCHEMPHYSCHEM, Issue 7 2008Katarína Gmucová Dr. Abstract The effect of electric and magnetic fields on the sandwich structure Pt/hydrogenated amorphous silicon (a-Si:H)/stearic acid monolayer/Langmuir,Blodgett film of Ag/Co nanoparticles encapsulated in an organic envelope is studied. This structure is used as a working electrode in an electrochemical cell filled with NaCl solution (1 mM) and equipped with an Ag/AgCl reference electrode. Reversible changes in voltammograms are observed due to treatments (negative or positive bias voltage and simultaneous laser irradiation) applied to the designed structure before measurements. As an explanation of the observed phenomena we suggest that both the Co-up and Ag-up (on the a-Si:H surface) orientation orderings of nanoparticle Ag/Co cores are repeatedly reached. The role of the photovoltaic material (a-Si:H) in the observed behavior is explained. Voltammetric measurements with an applied magnetic field support our idea about the orientation ordering of nanoparticle cores. [source] Redox Couple of DNA on Multiwalled Carbon Nanotube Modified ElectrodeELECTROANALYSIS, Issue 14 2009Hongxia Luo Abstract It has been envisioned that carbon nanotubes could promote electron-transfer reactions when used as electrode materials in electrochemical cells. In the present study, calf thymus DNA was electrochemically oxidized at an electrode modified with multiwalled carbon nanotubes. The potentials for DNA oxidation at pH,7.0 were found to be 0.71 and 0.81,V versus SCE, corresponding to the oxidation of guanine and adenine residues, respectively. An initial oxidation of adenine was observed in the first scan, which was followed by a quasi-reversible redox process of the oxidation product in the subsequent scans. [source] Efficient and Long-Living Light-Emitting Electrochemical CellsADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Rubén D. Costa Abstract Three new heteroleptic iridium complexes that combine two approaches, one leading to a high stability and the other yielding a high luminescence efficiency, are presented. All complexes contain a phenyl group at the 6-position of the neutral bpy ligand, which holds an additional, increasingly bulky substituent on the 4-position. The phenyl group allows for intramolecular ,,, stacking, which renders the complex more stable and yields long-living light-emitting electrochemical cells (LECs). The additional substituent increases the intersite distance between the cations in the film, reducing the quenching of the excitons, and should improve the efficiency of the LECs. Density functional theory calculations indicate that the three complexes have the desired ,,, intramolecular interactions between the pendant phenyl ring of the bpy ligand and the phenyl ring of one of the ppy ligands in the ground and the excited states. The photoluminescence quantum efficiency of concentrated films of the complexes improves with the increasing size of the bulky groups indicating that the adopted strategy for improving the efficiency is successful. Indeed, LEC devices employing these complexes as the primary active component show shorter turn-on times, higher efficiencies and luminances, and, surprisingly, also demonstrate longer device stabilities. [source] | |||||||||||||||||||