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Electrode Area (electrode + area)

Distribution by Scientific Domains

Chemistry	75%

Selected Abstracts

Microdimensional Polyaniline: Fabrication and Characterization of Dynamics of Charge Propagation at Microdisk Electrodes

ELECTROANALYSIS, Issue 17 2004
Karolina Caban
Abstract We describe fabrication of microdimensional polyanilne films in a controlled manner by voltammetric potential cycling or controlled potential electrolysis on platinum microdisk electrodes. The film grows in a form of hemispherical microdeposits, and its size largely exceeds the size of a Pt microdisk. Consequently, the film covers both the Pt substrate as well as the surrounding glass seal. Since the adhering polyaniline layer is conducting, the latter situation may lead to an increase in the effective electrode surface area. The lateral growth of polyaniline films outside the microdisk has also been demonstrated by performing diagnostic voltammetric experiments with use of a double microdisk set-up in which independent polarization of each disk is feasible. Microelectrode-based chronocoulometry, that involves an uncomplicated well-defined reduction potential step starting from the emeraldine (conducting) form and ending at leucoemeraldine (nonconducting) form, yields (upon application of a sufficiently short pulse) a well-defined linear response of charge versus square root of time that is consistent with the linear effective diffusion as the predominant charge propagation mechanism. When describing the system kinetics in terms of the effective (apparent) diffusion coefficient, we expect this parameter to be on the level of 10,8,cm2 s,1 or lower. The relative changes in dynamics of charge transport are discussed with respect to the polyaniline film loading, the size of microdisk electrode, expansion of the active electrode area, and the choice of electrolyte (strong acid) anion. The results are consistent with the view that when Pt microelectrode is modified with PANI deposit exceeding the size of the microdisk substrate, it behaves in a way as if its surface area is effectively much larger than the geometric area of Pt microdisk. [source]

Optimisation and Evaluation of La0.6Sr0.4CoO3,,,, Cathode for Intermediate Temperature Solid Oxide Fuel Cells

FUEL CELLS, Issue 5 2009
Youkun Tao
Abstract In this work, La0.6Sr0.4CoO3,,,,/Ce1,,xGdxO2,,,, (LSC/GDC) composite cathodes are investigated for SOFC application at intermediate temperatures, especially below 700,°C. The symmetrical cells are prepared by spraying LSC/GDC composite cathodes on a GDC tape, and the lowest polarisation resistance (Rp) of 0.11,,,cm2 at 700,°C is obtained for the cathode containing 30,wt.-% GDC. For the application on YSZ electrolyte, symmetrical LSC cathodes are fabricated on a YSZ tape coated on a GDC interlayer. The impact of the sintering temperature on the microstructure and electrochemical properties is investigated. The optimum temperature is determined to be 950,°C; the corresponding Rp of 0.24,,,cm2 at 600,°C and 0.06,,,cm2 at 700,°C are achieved, respectively. An YSZ-based anode-supported solid oxide fuel cell is fabricated by employing LSC/GDC composite cathode sintered at 950,°C. The cell with an active electrode area of 4,×,4,cm2 exhibits the maximum power density of 0.42,W,cm,2 at 650,°C and 0.54,W,cm,2 at 700,°C. More than 300,h operating at 650,°C is carried out for an estimate of performance and degradation of a single cell. Despite a decline at the beginning, the stable performance during the later term suggests a potential application. [source]

Novel Fabrication of Ca-Doped LaNbO4 Thin-Film Proton-Conducting Fuel Cells by Pulsed Laser Deposition

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2010
Anna Magrasó
Thin films of 0.5% Ca-doped La0.995Ca0.005NbO4,, (LCNO) proton-conducting electrolytes of ,2 ,m thickness were obtained by pulsed laser deposition on NiO,LaNbO4 composite substrates. The morphology of the films was granular after annealing at T,1000°C and evolved to spherical-like grains at 1100°C and above. The structure and composition of the films were characterized by X-ray diffraction and X-ray photoelectron spectrocopy. LCNO films showed the monoclinic fergusonite-type structure at room temperature. The area-specific resistance for a ,2-,m-thick electrolyte was in the order of 0.4 ,·cm2 at 600°C based on estimates of the electrode area. Temperature dependency of the electrical conductivity at 600°,700°C was comparable with that of bulk disks of the material. [source]

Disposable Gold Electrodes with Reproducible Area Using Recordable CDs and Toner Masks

ELECTROANALYSIS, Issue 1 2006
Denise Lowinsohn
Abstract The fabrication and characterization of very cheap disposable gold disk electrodes with reproducible area is reported. The innovation of the proposed procedure is the use of toner masks to define reproducible areas on uniform gold surfaces obtained from recordable compact disks (CD-R). Toner masks are drawn in a laser printer and heat transferred to gold surfaces, defining exactly the electrodes area. The electrochemical behavior of these disposable electrodes was investigated by cyclic voltammetry in Fe(CN)64, solutions. The relative standard deviation for signals obtained from 10 different gold electrodes was below 1 %. The size of the disk electrodes can be easily controlled, as attested by voltammetric responses recorded by using electrodes with radii varying from 0.5 to 3.0,mm. The advantages of using this kind of electrode for analytical measurements of substances that strongly adsorb on the electrode surface such as cysteine are also addressed. [source]