Year

2003

Degree Name

Doctor of Philosophy

Department

Department of Chemistry

Abstract

The discovery of carbon nanotubes in 1991 attracted a great deal of interest resulting in numerous investigations into their unique electrical and mechanical properties. The development of fabrication methods that allows preparation of aligned carbon nanotube arrays has been of particular interest lately.

Pyrolysis of iron (II) phthalocyanine in one zone of a furnace and subsequent deposition of carbon nanotubes (CNTs) in the second higher temperature zone in the same furnace has been investigated in this work. The resulting multi wall carbon nanotubes (MWNT), with average diameter 50 nm and length 15 um are well aligned and normal to the quartz substrate onto which they are deposited in the second zone of the furnace.

The electrochemical properties of the aligned carbon nanotube arrays been investigated and compared with other common electrodes eg. gold glassy carbon. The highly accessible surface area of the carbon nanotube arrays results in much greater current density per unit geometric area iron (II) ferricyanide was used. Enhanced current densities per unit geometric area were also observed for biomolecules such as hydroquinone, dopamine and epinephrine on the carbon nanotube electrodes.

The coating of individual aligned carbon nanotubes with conducting polymer has been demonstrated. The formed carbon nanotube-conducting polymer composite shows much higher mechanical properties than conducting polymer alone. The method used for electropolymerization has an impact on the uniformity of the conducting polymer coating. The use the potentiostatic technique yields smoother polymer coatings. The incorporation of enzymes into the conducting polymer coatings has been demonstrated. The high enzyme loading in the thin polymer layer results high sensitivity when used as a biosensor. It has been shown that the enhanced selectivity and sensitivity is due to both alignment of carbon nanotubes and the presence of iron particles on the tube tips as a result the pyrolysis process used to form the tubes.

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