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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.

This thesis presents the preparation of vertically aligned carbon nanotubes using porous anodic alumina templates via thermal chemical vapour deposition. The characteristics of prepared carbon nanotubes in terms of tube diameter, length, density, uniformity and alignment were investigated. The formation of porous anodic alumina membranes was studied. In order to prepare well-ordered porous anodic alumina templates, three approaches towards anodization of aluminium were examined. Effects of Al surface morphology and anodization conditions on the formation of the porous anodic alumina membrane were investigated. Co catalyst was electrochemically deposited at the bottom of the pores of porous anodic alumina templates by applying an alternating current. Prior to the AC electrodeposition, the barrier layer at the base of the pores was thinned in order to facilitate the deposition process. The thinning effect of three barrier layer thinning approaches was examined. The effect of electrodeposition duration on the pore filling was investigated. Carbon nanotubes were grown using Co-loaded porous anodic alumina templates via thermal chemical vapour deposition of C₂H₄. Effects of the presence of the Co catalyst, the amount of Co deposited at the bottom of the pores and the presence of water vapour on the carbon nanotube growth were examined. The characteristics of the grown carbon nanotubes in terms of tube diameter, length, density, uniformity and alignment were investigated. Moreover, a post-treatment after the carbon nanotube growth was proposed in order to obtain vertically aligned carbon nanotubes. In addition, vertically aligned carbon nanotubes were grown on Si chips. Two methods were used to prepare a catalytic layer on the Si chips for carbon nanotube growth.

Purification, chemistry and application are three very important aspects of current research on carbon nanotubes (CNTs). In the dissertation, the purification of nitric acid treated single-walled carbon nanotubes (SWNTs), the dissolution and dichlorocarbene addition of SWNTs, and the effects of chemically functionalized CNTs on neuronal growth are discussed.The nitric acid treated SWNTs were purified by chemical treatment, cross-flow filtration, and centrifugation methods. The effects of nitric acid treatment on the SWNTs and the efficiency of different purification methods was evaluated by the measurement of purify of SWNTs via solution phase NIR. Nitric acid reflux followed with controlled pH centrifugation can produce SWNTs with high purity. This purification mechanism was explained by the relationship of the concentration of the acidic sites on SWNTs and the zeta potential of SWNTs.The dissolution of SWNTs was achieved via chemical functionalization of SWNTs with octadecylamine (ODA). Dichlorocarbene addition to the sidewall of both ODA functionalized and as-prepared SWNTs was investigated. ODA functionalized HiPco-SWNTs were found to have the highest functionality of dichlorocarbene. Vis-NIR spectra of the dichlorocarbene functionalized SWNTs showed a significant decrease in the interband transitions of the semiconducting SWNTs, which indicated that the chemical functionalization of the sidewall of SWNTs changes the electronic properties of SWNTs. Far-IR spectra of the dichlorocarbene functionalized SWNTs showed a dramatic decrease in the electronic transitions at the Fermi level of metallic SWNTs, which was opposite to the effect of ionic doping by bromine. This difference in the far-IR spectroscopy can be used to distinguish covalent chemical functionalization and ionic doping effects of SWNTs.Chemically functionalized multi-walled carbon nanotubes (MWNTs) were applied as substrates for neuronal growth. By manipulating the charge carried by functionalized MWNTs we are able to control the outgrowth and branching pattern of neuronal processes. Chemically functionalized water soluble SWNTs graft copolymers were used in the modulation of outgrowth of neuronal processes. The graft copolymers were prepared by the functionalization of SWNTs with poly-m-aminobenzene sulphonic acid and poly-ethylene glycol. These functionalized water soluble SWNTs were able to increase the length of selected neuronal processes after their addition to the culturing medium.

This work concerns the interaction of intense, ultrashort laser pulses with fullerenes and carbon nanotubes. This includes the excitation and ionisation dynamics of gas phase fullerenes and the response of carbon nanotubes to intense ultrashort laser pulses. When ionising C60 with laser pulses of duration between 50 fs up to a few hundred fs, the ionisation mechanism has been proposed to be thermal in nature, with the electronic subsystem ‘hot’ and the vibrational system ‘cold’ at the time of ionisation. Recent results show an anisotropy in the photoelectron angular distribution which may suggest more direct mechanisms at work. Velocity-Map Imaging photoelectron spectroscopy results are presented for the ionisation of C60 and C70 at various wavelengths, pulse durations and intensities and the results are compared to theoretical models. The results are described well by a thermal ionisation mechanism in which a significant number of electrons are emitted during the laser pulse. Electrons may gain a momentum ‘kick’ from the electric field of the laser which results in an anisotropy in the photoelectron angular distributions. Peaks are observed, superimposed on the thermal background, in the photoelectron kinetic energy spectra of fullerenes ionised by ultrashort laser pulses which were previously assigned as Rydberg peaks. Photoelectron angular distributions of these peaks are presented for C60 and C70 ionised with laser pulses of various wavelengths. The binding energies and anisotropy parameters fitted to the peaks suggest that they are due to the population and one-photon ionisation of superatom molecular orbitals (SAMOs). The results rule out a direct multiphoton population mechanism for these states and show many similarities with Rydberg fingerprint spectroscopy. The fusion of carbon nanotubes has been observed under high energy electron beams and fullerene molecules have been shown to fuse together after irradiation with ultrashort laser pulses. Results are presented for experiments where fusion of carbon nanotubes with ultrashort laser pulses was attempted. Thin carbon nanotube films are analysed via Raman spectroscopy after irradiation by single laser pulses. A number of low frequency radial breathing mode peaks were observed which suggest that fusion may have taken place at certain areas of the sample.

This thesis covers synthesis and characterisation of TiO2 nanotubes and TiO2 / Li4Ti5O12 composite nanotubes. The aim was to build batteries with high areal capacity and good rate capability. TiO2 nanotubes were synthesized by two step anodization of titanium metal foil and the composite electrodes were synthesized through electrochemical lithiation of TiO2 nanotubes. To improve the battery performance the TiO2 nanotubes were annealed at 350 °C in air atmosphere, while the composite electrodes were annealed in argon at 550 °C. The longest TiO2 nanotubes were measured to 42.5 μm. The 40 μm long nanotubes displayed an areal capacity of 1.0 mAh/cm2 and a gravimetric capacity of 89 mAh/g. Nanotubes having a length of 10 μm had an areal capacity of 0.33 mAh/cm2 and a gravimetriccapacity of 130 mAh/g. When cycled at high rates, 10C, the capacity of the 40 μm nanotubes was 0.25 mAh/cm2, using a current density of 9.3 mA. The capacity of the 40 μm long nanotubes were higher than for the 10 μm long, but the increase was not proportional to the increase in length. A composite electrode was successfully synthesized and was found to have a capacity of 0.25 mAh/cm2 at a rate of C/5.

Extensive research efforts are underway to generate composite coatings including carbon nanotubes (CNT) in order to improve the properties of the bulk coat. The present project concentrates on possible methods that would allow the plasma spraying of CNT-based nano-composite coatings. Various methods for producing metal-CNT composite powders for thermal plasma spraying are studied in this project. The first method discussed is based on CNT dispersion followed by an agglomeration procedure using a polymer binder. The second and more promising technique gets around the problems associated with handling, separating, and transporting the nanotubes to the substrate through a direct synthesis of the CNT on the particles to be sprayed. In the present context, this synthesis is made on pretreated stainless steel SS304 powders by chemical vapor deposition (CVD). A parametric study is made for the various steps of the thermal CVD process by varying parameters such as the etching time in the pre-treatment sequence, while the reaction temperature, the annealing temperature, the growth phase duration and the acetylene injection time are varied for the CVD sequence. The composite powders are analyzed using high resolution electron microscopy images (FEGSEM), thermogravimetric analyses (TGA), Raman spectroscopy, and BET surface area analyses. This study provided the parametric optimization of the thermal CVD procedure with respect to CNT production. The composite powders generated show a dense, fully covered, and uniform CNT forest with a purity of CNT to amorphous carbon of 86% based on the micro-Raman spectra obtained.

<p>In this study we report on the effect of the deposition parameters on the morphology and structural properties of CNTs, synthesized by means of the hot-wire chemical vapour deposition technique. SEM, Raman and XRD results show that the optimum deposition conditions for the HWCVD synthesis of aligned MWCNTs, with diameters between 50 and 150 nm and lengths in the micrometer range are: Furnace temperature of 500 &ordm / C, deposition pressure between 150 and 200 Torr, methane/hydrogen dilution of 0.67 and a substrateto- filament distance of 10 cm.</p>

This thesis is based on two main parts. The first part concerns purification and functionalization of carbon nanotubes (papers I-III), and the second part is related to the synthesis of organometallic fullerene derivatives (papers IV-VII): Two oxidative methods involving aqueous nitric acid were compared with respect to their capability to introduce carboxylic groups into single walled carbon nanotubes, and several literature methods for esterification and amidation of these groups have been evaluated with focus on efficiency and reproducibility in forming covalently functionalized products soluble in organic media. Amidation proceeding via a SWNT-(COCl)n intermediate yielded the expected covalent product, whereas carboxylate salt formation dominated with other attempted methods. Esterification was achieved via the acyl chloride method and via alkylation of SWNT-(COO–)n, the latter being the more efficient method. A new, reagent-free method for purification of single- and multi walled carbon nanotubes has been developed. Microwave treatment dissociates non-nanotube carbon and disperses it into an organic solvent, resulting in very pure carbon nanotubes within a few minutes of heating, without the involvement of acidic/oxidative reagents. According to thermogravimetric analysis, Raman and IR spectroscopy, as well as SEM, the process yields nanotubes with a low degree of defects. A non-covalent approach has been employed to prepare nanotubes functionalized with glycosides. Derivatives of galactose and lactose were covalently linked to a pyrene moiety and the thus formed pyrene-glycosides were non-covalently attached to single- and multi walled carbon nanotubes by π-π interactions. Fluorescence titrations have been used to quantify the formed supramolecular assemblies, which for SWNTs exhibits increased water solubility. A fulleropyrrolidine-(tricarbonyl)chromium complex was synthesized and fully characterized. IR spectroelectrochemistry was used to probe the redox state of the fullerene and provided evidence for electronic communication between the two electroacive moieties. A C60-ferrocene-C60 triad system was synthesized and characterized. Cyclic voltammetry and fluorescence studies suggested electronic communication between ferrocene and the two fullerenes. Finally, the synthesis and initial characterization of short fullerene-ferrocene oligomers are presented.