Recently, there has been a growing demand for electrode materials to serve as electrochemical capacitors (EC). It has been an important issue to come up with environment friendly electric power sources to reduce pollution caused by combustion engines of automotive systems. Even though conventional battery systems and fuel cells supply high energy, they lack the high specific power that would be required for hybrid power sources. The ECs can fill the gap between conventional capacitors and batteries. / Carbon nanotubes (CNTs), discovered by Iijima in 1991, attracted great attention in recent years for their unique properties, such as mesoporous character, excellent conductivity, moderate to high specific surface area as well as chemical and mechanical stability. These properties of CNTs make them useful in a wide of range applications including electrode materials for EC applications. / The preparation of CNT electrodes is accomplished by either pasting them onto metallic current collectors with the use of binder materials such as PVDF or growing them from deposited metal nanoparticles on substrates such as graphite paper. The deposition of metal nanoparticles is achieved via sputtering techniques or lengthy electrochemical deposition methods. The aim of this research was to simplify the preparation step by growing CNTs directly on metallic substrates and to study the relationship between surface area and electrochemical capacitance of CNTs. CNTs were produced on metal-alloy grids via chemical vapor deposition (CVD) of acetylene (C2H2). The physical characterization of the samples was achieved by Field Emission Scanning Electron Microscopy (FE-SEM), Raman spectroscopy and Single point BET surface area. The electrochemical performance of the samples was evaluated by cyclic voltammetry (CV) in a three electrode electrochemical cell with 1M sulfuric acid (H2SO4) solution as the electrolyte.

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Thesis (M.Eng)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: leaf 96-106.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 74-75) Also available in print.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: fuel cell. Includes bibliographical references (p. 76).

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Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisor: George W. Luther, III., College of Marine & Earth Studies. Includes bibliographical references.

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Electrochemical impedance spectroscopy (EIS) is a technique consisting of the application of a small perturbing current or voltage to an electrochemical system and measuring the response of the system. The response of the system can be described through the notion of impedance, Z, which is defined as the transfer function between the voltage and the current signal. By describing the impedance, one can gain insight into the interpretation of EIS experiments for the measurement of fundamental physical properties (eg diffusion coefficients). The impedance responses of electrochemical systems have been described in the past as an arrangement of ideal equivalent-circuit elements. Simple lumped-parameter circuits and more complex finite-transmission-line circuits have been used in the past, but the disadvantage of this approach is the difficulty in interpreting the equivalent-circuit parameters in terms of fundamental properties. It is then interesting to determine impedance by describing mathematically the fundamental physical processes that govern the response of the system. By describing and predicting analytically the impedance response induced by the perturbing current signal, one can: (i) gain considerable insight into the electrochemical process of interest, (ii) make explicit use of the modeling approach to address operational issues such as process design optimization, monitoring, diagnostics and control, and (iii) offer an interpretation to carefully designed EIS experiments for the measurement of fundamental physical properties such as diffusion coefficients or surface of active catalyst.