The Electrochemical and Spectroscopic Characterization of Carbon Nanotube Materials and The Development of Multiple Electrochemical Sensor

Carbon plays a major role in electrochemistry as an electrode material. It exhibits slow kinetics of electrode oxidation, which leads to a wide potential window with low residual current and makes the electrode versatile for studying many redox reactions. Carbon nanotubes (CNTs) are allotropes of sp2 carbon with a cylindrical structure. They possess a remarkable variety of structural, mechanical, chemical and electronic properties. Chemical stability and high current densities give desirable properties to carbon nanotube materials for the field of electrochemistry.;Spectroelectrochemistry is the combination of species-focused spectroscopy with reaction-oriented electrochemistry. It uniquely employs electrochemistry and spectroscopy in a single device. In contrast to the essentially physical spectroscopic techniques, which are well suited for species characterization, electrochemistry provides the capability of monitoring a chemical reaction occurring at an interface, typically between a solution (analyte of interest in electrolyte) and an electrode.;The Heineman research group at the University of Cincinnati has been working on characterizing different materials using electrochemical and spectroscopic techniques and developing electrochemical, spectroelectrochemical sensors and biosensors based on those novel materials. This dissertation presents the results of six aspects of the projects in the Heineman group.;The first study includes the characterization of novel catalyst free CNT disk electrodes. The electrochemical properties of CNT disk electrodes were compared with commercial glassy carbon electrode and showed a much faster heterogeneous electron transfer rate and larger microscopic surface area. The second study investigated the properties of catalyst free CNT loaded Nafion film and its application in making metal ion sensors. The third study focused on characterizing the CNT transparent film synthesized by a chemical vapor deposition process and the study of the spectroelectrochemical application of the CNT film. In the fourth study, the application of both the thin layer electrochemical cell and a CNT disk electrode was demonstrated for detection of nitrate (an environmental hazard at high concentration) when combined with the selective biological element nitrate reductase. The fifth work is a study of the redox properties of the nitrate reductases using spectroelectrochemistry and other electrochemical techniques. The sixth study is part of a project funded by the NSF-Engineering Research Center (NSF-ERC), which was established for developing implantable metallic materials (mainly Mg and its alloys) with feedback control. The Heineman group is interested in developing sensors to monitor the corrosion of ERC Mg alloys and this dissertation involves the in vivo characterization of Mg alloys using an amperometric H2 microsensor.