Year

2012

Degree Name

Doctor of Philosophy

Department

Department of Chemistry

Abstract

Within this thesis we demonstrate the formation of 3-dimensional, potentially freestanding, entangled carbon nanotube architectures through the use of previously untested organo-metallic catalysts, Iron (III) Tosylate, Cobalt (II) Tosylate, and Nickel (II) Tosylate. The effect of catalyst concentration, hydrocarbon decomposition temperature and growth time were examined in terms of the produced architectures morphologies. As capacitive devices these as produced carbon nanotube architectures demonstrated impressive maximum capacitances of up to 182.9 F/g with a power density of 15 kW/kg and an energy density of 4.06 Wh/kg.

In addition we develop and optimise the decoration of metallic nanoparticles including, platinum, palladium, gold, ruthenium and various bi-metallic particles onto both individual carbon nanotubes and pre-formed carbon nanotube architectures in under 60s through the use of microwave chemistry. In addition to being exceptionally rapid this reduction technique was shown to be extremely versatile, with a range of different metallic architectures being synthesised, ranging from individual particles, to clustered particle morphologies. The role of pH, microwave intensity and salt concentration were examined.

The most efficient configuration of platinum nanoparticles onto the entangled carbon nanotube architecture produced a maximum capacitive response of 640 F/g at a maximum energy density of 5.25 Wh/kg and a maximum power density of 77 kW/kg. Examination of this electrode as a cathode in a hydrogen fuel cell yielded extremely promising results with a maximum current density of 3000 mA/cm2 and a power density of 940 mW/cm2 corresponding to an efficiency of 0.81 mgPt/kW, approaching the United States Department of Energy target of 0.3 mgPt/kW.

This work provides a pathway to the development of 3-dimensionally structured carbon/metal nanoparticle composite materials for a broad range of applications, specifically focused on electrochemical devices.

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