Boron-doped carbon nanotubes are predicted to behave as semiconductors over a large range of diameters and chiralities and might thus constitute a suitable class of material for nanoelectronics technology. Boron-doped CNTs were reported as by-products when BC2N nanotubes were prepared by an arc-discharge method. The potential doping of CNTs with different kinds of atoms might provide a mechanism for controlling their electronic properties. We have synthesized boron-doped carbon nanotubes (CNTs) directly on copper catalyst by decomposition of B(OCH3)3 in chemical vapor deposition method. The results were characterized and analyzed by scanning electron microscopy (SEM), Raman, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), solid-state NMR and TGA.

This thesis presents the fabrication of transparent conductive Boron-Doped CVD diamond (BDD) thin film with the appropriate processing parameters. The BDD shows the transmittance in the visible wavelength and good electrical conductivity. The depositing rate of Diamond films yields 0.37 £gm per hour with Hydrogen, Argon, Methane and oxygen as gas sources, and B(OCH3)3 was used as the doping source. Microwave plasma chemical vapor deposition (MWCVD) was performed for the BDD deposition. Also, PECVD was applied to grow diamond-like Carbon (DLC) film on silicon as substrate. Through systematical experiments, the influence of carrier gas flow rates of B(OCH3)3, the variation of ratio of Argon, and growth pressure of BDD on the transmittance in the visible light and electrical conductivity has been studied. In addition, dc bias was applied to synthesize diamond films and extend long depositing time shows the stable growth rate of diamond films. The thickness of BDD films increases and acquired more than 60% optical transmittance. BDD samples were analyzed by Raman Spectroscopy for the diamond quality, N & K Analyzer for the film thickness and optical properties. Van Der Pauw I-V Measurement and Hall Measurement were analyzed p-type diamond films carrier mobility, carrier concentration, electrical resistivity. By increasing Argon and applying negative dc bias can improve the growth rate and transmittance of diamond films. And the quality of diamond films could be improved by the coating of DLC on Si substrates. This work has achieved fabricating a transparent conducting BDD successfully.

The fabrication and characterization of boron-doped diamond microelectrodes for use in electrochemical detection coupled with capillary electrophoresis (CE-EC) is discussed. They exhibited low and stable background currents and sigmoidally shaped voltammetric curves for cysteine, cystine and Fe(CN)63-/4- . Evaluation of the CE-EC system and the electrode performance were accomplished using a 10 mM borate buffer, pH 8.8, run buffer, and a 70-cm-long fused-silica capillary (10-mm i.d.) with seven sulfur-containing amino acids (methionine, cysteine, cystine, homocysyeine, homocystine, glutathionine, glutathionine disulfide) as test analytes. Reproducible separation (elution time) and detection (peak current) of seven sulfur-containing amino acids were observed with response precisions of 5% or less.

The current treatment of water contaminated with organic compounds includes adsorption, air stripping, and advanced oxidation processes. These methods large quantities of water and require excessive energy and time. A novel treatment process of concentrating and then electrochemically oxidizing compound would be a more feasible practice. This research investigated the oxidative destruction of perfluorooctane sulfonate (PFOS), perfluorobutane sulfonate (PFBS) and trichloroethene (TCE) at boron-doped diamond film electrodes and the adsorption of PFOS and PFBS on granular activated carbon and ion exchange resins.Experiments measuring oxidation rates of PFOS and PFBS were performed over a range in current densities and temperatures using a rotating disk electrode (RDE) reactor and a parallel plate flow-through reactor. Oxidation of PFOS was rapid and yielded sulfate, fluoride, carbon dioxide and trace levels of trifluoroacetic acid. Oxidation of PFBS was slower than that of PFOS. A comparison of the experimentally measured apparent activation energy with those calculated using Density Functional Theory (DFT) studies indicated that the most likely rate-limiting step for PFOS and PFBS oxidation was direct electron transfer. The costs for treating PFOS and PFBS solutions were compared and showed that PFOS is cheaper to degrade than PFBS.Screening studies were performed to find a viable adsorbent or ion exchange resin for concentrating PFOS or PFBS. Granular activated carbon F400 (GAC-F400) and an ion exchange resin, Amberlite IRA-458, were the best methods for adsorbing PFOS. Ionic strength experiments showed that the solubility of the compounds affected the adsorption onto solid phases. Regeneration experiments were carried out to determine the best method of recovering these compounds from the adsorbents; however, the compounds could not be effectively removed from the adsorbents using standard techniques.The electrochemical oxidation of trichloroethene (TCE) at boron-doped diamond film electrodes was studied to determine if this would be a viable degradation method for chlorinated solvents. Flow-through experiments were performed and showed TCE oxidation to be very rapid. Comparing the data from the DFT studies and the experimentally calculated apparent activation energies the mechanism for TCE oxidation was determined to be controlled by both direct electron transfer and oxidation via hydroxyl radicals.

<p> Ni K extended X-ray absorption fine structure spectroscopy recorded with synchrotron radiation at 77 K and 300 K, has been used to investigate various annealed Pd40Ni40P20 metallic glass samples. The structural parameters (radial distance, coordination number, Debye Waller factor) for the Fourier filtered first coordination shell were obtained via curve analysis using MFIT (multifitting analysis) and plotted as a function of annealing temperature. Similar trends between 77 K and 300 K data were not observed in all cases. These results lead one to believe that the curve fitting procedure is not yet optimized and makes one sceptical of attributing any meaning to the results.</p> <p> X-ray absorption near edge spectroscopy via electron yield detection has also been used to study the B K edge in boron doped silicon. It was found that a strong peak at 195 eV is directly related to trigonally coordinated boron. Non trigonally coordinated boron did not seem to produce this spike. Results show that B 1s spectroscopy is a very sensitive probe of the local structure of boron.</p> / Thesis / Master of Science (MSc)

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Several electrochemical processes are modeled at process levels and atomic scales. Processes are presented for acid generation and ion exchange media regeneration, along with corresponding process models. Transport and reaction processes in individual ion exchange beads are also modeled. Acids of mild strength (pH = ~1-2) are generated from electrolyte solutions and their strength is effectively modeled as a function of time. The regeneration of ion exchange media is also modeled, to close agreement with measurements, and the process model is reconciled with a model for solute flux from an individual ion exchange bead. Together, the models show that the "gentle" regeneration process is controlled by the plating rate. Processes interior to the particle are controlled by diffusion, but all processes are faster than the characteristic time for plating. In a separate process, an electrochemical method is used to produce hypochlorite for disinfection. The process generates perchlorate as a toxic byproduct. Density function theory is used to construct an atomic-scale model of the mechanism for producing perchlorate, as well as the aging of the boron-doped diamond anode used in the process. The mechanism shows that the boron-doped diamond surface plays an important role in chemisorbing and stabilizing radicals of oxychlorine anions, allowing the radicals to live long enough to react and form higher ions like perchlorate. Wear mechanisms that occur on the anode are shown to oxidize and etch the surface, changing its chemical functionality over time. As the surface ages, the overpotential for water oxidation is decreased, decreasing the efficiency of the electrode.

The experimental work discussed in this thesis explores the effects of metal modification on the electroanalytical ability of boron doped diamond electrodes. Boron doped diamond (BDD) electrodes have found increased application to electroanalysis in the past two decades, yet relatively little of the literature is focused on metal, nano and microparticle modification of the substrate. In this thesis three metals have been used to modify the BDD electrode; bismuth, antimony and nickel. Bismuth and antimony nanoparticle modified BDD electrodes were directly compared to unmodified BDD and a bulk bismuth electrodes in the determination of trace levels of cadmium and lead using anodic stripping voltammetry. In both instances, the modified electrode allowed for the simultaneous determination of each analyte that was otherwise unattainable at the unmodified BDD electrode. The nickel modified BDD (Ni-BDD) electrode was used in the determination of organic analytes, namely glucose, methanol, ethanol and glycerol. The nickel nano and microparticle electrodes gave the characteristic Ni(OH)₂/NiOOH redox couple in alkali pH, the oxidised form of which (NiOOH) catalysed the oxidation of the organic analytes. The chapter on glucose sensing with the Ni-BDD electrode is preceded by an extensive literature review on the advances of non-enzymatic glucose sensing, and the application of catalytic metals and nanomaterials in this field. Throughout the course of this DPhil, there has been a collaborative project between Asylum Research and myself within the Compton group to develop a commercial electrochemical atomic force microscope (EC-AFM) cell. The aim was to produce an adaptable EC-AFM cell capable of dynamic electrochemical experiments whilst simultaneously or instantaneously acquiring an AFM image of the modified surface, in-situ. This project was successful, and the EC-AFM cell has contributed to a number of chapters in this thesis, and has now been commercialised.

The aim to this work was to develop methods for the determination of 2 aminobiphenyl (2-AB), 3 aminobiphenyl (3-AB), and 4-aminobiphenyl (4-AB) in model mixtures. Concretely, the direct determination of the mixture of studied analytes has been tested using spectrophotometry and differential pulse voltammetry (DPV). Furthermore, separation and detection of 2-AB, 3-AB, and 4-AB have been performed using high performance liquid chromatography with electrochemical detection (HPLC-ED) with boron-doped diamond film thin electrode (BDDFE) in ,,wall-jet" configuration and using high performance liquid chromatography with UV detection (HPLC-UVD). It was found out that the spectrophotometric determination of 2-AB, 3-AB, and 4-AB is impossible in their mixture because of nearby values of local absorption maxima wavelengths of all three analytes studied. Upon the determination of 2-AB, 3-AB, and 4-AB in their mixture using DPV in BR buffer pH 2.0, the difference in peak potentials of 2-AB and 3-AB is too low for their determination in mixture. Upon the determination of mixture containing 2-AB and 4-AB in BR buffer pH 12.0, the limits of determination (LDs) were obtained in the concentration order of 10-6 mol.l-1 for 2-AB and 10-7 mol.l-1 for 4-AB. LDs for the mixture containing 3-AB and 4-AB were obtained in the...