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Využití bórem dopované diamantové filmové elektrody k voltametrické a ampérometrické detekci aminobifenylů / The utitilization of boron-doped diamond thin film electrode for the voltammetric and amperometric determination of amino derivatives of biphenylMaixnerová, Lucie January 2010 (has links)
The aim to this work was to develop methods for the determination of 2 aminobiphenyl (2-AB), 3 aminobiphenyl (3-AB), and 4-aminobiphenyl (4-AB) in model mixtures. Concretely, the direct determination of the mixture of studied analytes has been tested using spectrophotometry and differential pulse voltammetry (DPV). Furthermore, separation and detection of 2-AB, 3-AB, and 4-AB have been performed using high performance liquid chromatography with electrochemical detection (HPLC-ED) with boron-doped diamond film thin electrode (BDDFE) in ,,wall-jet" configuration and using high performance liquid chromatography with UV detection (HPLC-UVD). It was found out that the spectrophotometric determination of 2-AB, 3-AB, and 4-AB is impossible in their mixture because of nearby values of local absorption maxima wavelengths of all three analytes studied. Upon the determination of 2-AB, 3-AB, and 4-AB in their mixture using DPV in BR buffer pH 2.0, the difference in peak potentials of 2-AB and 3-AB is too low for their determination in mixture. Upon the determination of mixture containing 2-AB and 4-AB in BR buffer pH 12.0, the limits of determination (LDs) were obtained in the concentration order of 10-6 mol.l-1 for 2-AB and 10-7 mol.l-1 for 4-AB. LDs for the mixture containing 3-AB and 4-AB were obtained in the...
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Synthesis and electrochemical studies of nitroxide radical polymer brushes via surface-initiated atom transfer radical polymerizationWang, Yu-Hsuan 27 July 2010 (has links)
A non-crosslinking approach that covalently bonds nitroxide polymer brushes onto the ITO substrates via surface-initiated atom transfer radical polymerization (ATRP) was develpoed. Since the indium tin oxide (ITO)-silane covalent bonding providesvery strong chemical bonds to adsorb the nitroxide polymer brushes on ITO, it prevents polymers from dissolving into electrolyte solvent and thus improves its electrochemical properties.
Moreover, micro-contact printing technology was used to pattern nitroxide polymer brushes on an ITO surface for the potential application in microbatteries. The morphology of electrodes was observed by atomic force microscopy.The electrochemical properties of the cathode were also studies.
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Synthesis and electrochemical characteristics of nitroxide polymer brushes for thin-film electrodesHung, Miao-ken 27 June 2012 (has links)
We reported a non-crosslinking approach to synthesize nitroxide radical polymer brushes for thin-film electrodes via surface-initiated atom transfer radical polymeization (SI-ATRP), which was effective to yield the organic radical polymer brushes with high grafting density and to attain a uniform surface. As mentioned above, the covalent bonding of nitroxide polymer brushes to the conducting substrate not only prevented the polymer dissolution into organic electrolyte solution but improved the cycle life performance of batteries. Moreover, they can be the potential application in microbatteries by using microcontact printing to produce the patterned nitroxide polymer brushes on a conducting substrate.
Even though the organic radical polymer brushes provided a new approach to syn-thesize thin-film electrodes, they still existed many problems that needed to study and to figure out. We discussed the morphology and electrochemical performance about ni-troxide radical polymer in the thesis. In the measurement of surface properties, we used the contact angle, electron spectroscopy for chemical analysis (ESCA) and atomic force microscopic (AFM) to proceed. Another, in the measurement of electrochemical analysis, we used the cyclic voltammetry(CV), alternating current (AC) impedance and charge-discharge to understand the regarding mechanism in this polymer layer during the electrochemical reaction.
In chapter 4, we discussed the oxidative problem in the polymer brushes. It should be well controlled during the oxidation reaction, because the oxidation level may affect the diffusion of electron that resulted the capacity better or not. In chapter5, we controlled the density of polymer brushes to construct the possible mechanism during the electro-chemical reaction, and found out the possible factors that affected the electrochemistry. In chapter 6, we applied the better results from the front chapter to the organic radical battery, and compared their electrical performance.
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Synthesis and Characterization of Nanostructured Electrodes for Solid State Ionic DevicesZhang, Yuelan 20 November 2006 (has links)
The demands for advanced power sources with high energy efficiency, minimum environmental impact, and low cost have been the impetus for the development of a new generation of batteries and fuel cells. One of the key challenges in this effort is to develop and fabricate effective electrodes with desirable composition, microstructure and performance. This work focused on the design, fabrication, and characterization of nanostructured electrodes in an effort to minimize electrode polarization losses.
Solid-state diffusion often limits the utilization and rate capability of electrode materials in a lithium-ion battery, especially at high charge/discharge rates. When the fluxes of Li+ insertion or extraction exceed the diffusion-limited rate of Li+ transport within the bulk phase of an electrode, concentration polarization occurs. Further, large volume changes associated with Li+ insertion or extraction could induce stresses in bulk electrodes, potentially leading to mechanical failure. Interconnected porous materials with high surface-to-volume ratio were designed to suppress the stress and promote mass transport. In this work, electrodes with these unique architectures for lithium ion batteries have been fabricated to improve the cycleability, rate capability and capacity retention.
Cathodic interfacial polarization represents the predominant voltage loss in a low-temperature SOFC. For the first time, regular, homogeneous and bimodal porous MIEC electrodes were successfully fabricated using breath figure templating, which is self-assembly of the water droplets in polymer solution. The homogeneous macropores promoted rapid mass transport by decreasing the tortuosity. And mesoporous microstructure provided more surface areas for gas adsorption and more TPBs for the electrochemical reactions. Moreover, composite electrodes were developed with a modified sol-gel process for honeycomb SOFCs. The sol gel derived cathodes with fine grain size and large specific surface area, showed much lower interfacial polarization resistances than those prepared by other existing processing methods.
Nanopetals of cerium hydroxycarbonate have been synthesized via a controlled hydrothermal process in a mixed water-ethanol medium. The formation of the cerium compound depends strongly on the composition of the precursors, and is attributed to the favored ethanol oxidation by Ce(IV) ions over Ce(IV) hydrolysis process. Raman studies showed that microflower CeO2 preferentially stabilizes O2 as a peroxide species on its surface for CO oxidation.
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