In the global search for renewable sources of energy, hydrogen is a promising candidate in transportation and electronic applications. Carbon nanotubes (CNTs) have the largest hydrogen storage capacity among the hydrogen storage materials known at present. The Ni-MH battery can be used to store and then discharge large amounts of hydrogen reversibly by using hydrogen storage materials as negative electrode. The electrochemical hydrogen storage performances of metal hydride electrodes with different levels of multi wall carbon nanotubes (20%, 15%, 10%, 5% and 2% of Ni-MH battery's active materials) has been investigated under similar charge-discharge conditions. Electrochemical test cell consisted of a single hydrogen storage negative electrode sandwiched between two NiOOH/Ni(OH)2 positive electrodes. A 6M aqueous KOH solution was used as electrolyte. Electrochemical properties such as specific discharge capacity, high rate charge-discharge capability and cycle life stability have been investigated. The morphology and structure of negative electrode material were examined by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. Chemical analysis of the hydrogen storage alloy was performed using electron probe microanalysis, electron diffraction spectroscopy and induced coupled plasma spectroscopy analysis. Hydrogen absorption-desorption properties were measured in terms of pressure-composition-isotherm curves. It has been found in this study that the presences of CNTs significantly enhanced the overall electrochemical properties of the Ni-MH battery. Maximum specific discharge capacity was observed for 5% CNTs electrode reaching 243 mAh/g, whereas 0% CNTs could only reach 229 mAh/g. High rate charge and discharge capabilities of 5% CNTs electrodes were ~ 241% and 250% higher than the corresponding values for 0% CNTs electrode. Furthermore, the differences in electrochemical hydrogen storage of CNTs with different diameters of 10-20 nm, 20-40 nm, 40-60 nm, and 60-100 nm were investigated. Electrochemical results demonstrated that CNTs with different diameters showed a large variation in the electrochemical hydrogen storage capability under the similar experimental condition. A comparison between electrodes with different CNTs studies was carried out in order to optimize nanotubes choices for Ni-MH battery. It was found that smaller tube diameters, 20-40 nm and 5% CNTs negative electrode showed the best electrochemical properties of Ni-MH battery system.

<p>In this diploma work I present the first experimental investigations</p><p>of carbon nanotubes at Karlstads University. Raw nanotube powder</p><p>of single walled carbon nanotubes have been dispersed primarily in</p><p>1,2-dichloroethane. The solutions have been spincoated on Au(111)</p><p>substrates. In order to determine the solubility of carbon nanotubes</p><p>in the solution the samples have been investigated in an atomic force</p><p>microscope.</p><p>Single walled carbon nanotubes deposited on a Au(111) substrate</p><p>have been investigated in a scanning tunneling microscope. Atomically</p><p>resolved STM images of single walled carbon nanotubes were obtained.</p><p>Scanning tunneling spectroscopy spectra was taken on a tube revealing</p><p>its chirality. The measured data from the nanotubes was compared to</p><p>calculations and confirmed their properties.</p><p>Dry direct contact transfers of individual single walled carbon nanotubes</p><p>have been done as a first step when trying to deposit carbon</p><p>nanotubes on reactive surfaces in ultra-high vacuum. Individual nanotubes</p><p>were found, confirming the success of dry direct contact transfer.</p>

Porous tin oxide nanotubes were obtained by vacuum infiltration of tin oxide nanoparticles into porous aluminum oxide membranes, followed by calcination. The porous tin oxide nanotube arrays so prepared were characterized by FE-SEM, TEM, HRTEM, and XRD. The nanotubes are open-ended, highly ordered with uniform cross-sections, diameters and wall thickness. The tin oxide nanotubes were evaluated as a substitute anode material for the lithium ion batteries. The tin oxide nanotube anode could be charged and discharged repeatedly, retaining a specific capacity of 525 mAh/g after 80 cycles. This capacity is significantly higher than the theoretical capacity of commercial graphite anode (372 mAh/g) and the cyclability is outstanding for a tin based electrode. The cyclability and capacities of the tin oxide nanotubes were also higher than their building blocks of solid tin oxide nanoparticles. A few factors accounting for the good cycling performance and high capacity of tin oxide nanotubes are suggested. / Singapore-MIT Alliance (SMA)

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Restricted until October 2006. Bibliography: leaves 88-94.

In this diploma work I present the first experimental investigations of carbon nanotubes at Karlstads University. Raw nanotube powder of single walled carbon nanotubes have been dispersed primarily in 1,2-dichloroethane. The solutions have been spincoated on Au(111) substrates. In order to determine the solubility of carbon nanotubes in the solution the samples have been investigated in an atomic force microscope. Single walled carbon nanotubes deposited on a Au(111) substrate have been investigated in a scanning tunneling microscope. Atomically resolved STM images of single walled carbon nanotubes were obtained. Scanning tunneling spectroscopy spectra was taken on a tube revealing its chirality. The measured data from the nanotubes was compared to calculations and confirmed their properties. Dry direct contact transfers of individual single walled carbon nanotubes have been done as a first step when trying to deposit carbon nanotubes on reactive surfaces in ultra-high vacuum. Individual nanotubes were found, confirming the success of dry direct contact transfer.

This research project is part of a larger Canadian endeavour to evaluate feasibility of using new nanocatalyst formulations for Fischer-Tropsch synthesis (FTS) to convert fossil-derived or renewable gaseous fuels into green diesel. The green diesel is a clean fuel (with no aromatics and sulfur compounds) suitable for the commonly used transportation system. The catalyst investigated is cobalt metal supported on carbon nanotubes (CNTs). The physical properties of CNTs have improved the common cobalt catalyst currently used in industry. Carbon nanotubes have high surface area, a very stable for FTS activity and, contrary to other common supports, do not interact with the catalyst active phase to produce undesirable compounds. Moreover, CNTs differ from graphite in their purity and by their cylindrical form, which increases the metal dispersion and allows confinement of the particles inside the tubes. Thus, carbon nanotubes as a new type of carbon material have shown interesting properties, favoring catalytic activity for FTS cobalt catalyst. Their surface area can be modified from 170 to 214 m^2/g through acid treatment. The CNT support lowers the amount of Ru promoter needed to increase the catalyst activity up to 80 % CO conversion and potassium promoter increases the selectivity for á-olefins. The olefin to paraffin (O/P) ratio for Co/CNT and CoK/CNT are 0.76 and 0.90, respectively. Moreover, the Co-Fe bimetallic catalysts supported on CNT have proved to be much more attractive in terms of alcohol formation, up to 26.3 % for the Co10Fe4/CNT. The structural characteristics of CNTs have shown to be suitable for use as catalytic support materials for FTS using microemulsion preparation method as applied to produce nanoparticle catalysts. Microemulsion technique results show uniform nanoparticle that are easy to reduce. In addition, the confinement of the particles inside the CNT has improved the lifetime of the catalyst by decreasing the rate of sintering. The deactivation rate at high FTS activity is linear (XCO = -0.13 t(hr) + 75) and at low FTS activity is related to a power law expression of order 11.4 for the cobalt particles outside the tubes and 30.2 for the cobalt particles inside the tube. The optimized catalyst studied was the CoRuK/CNT catalyst. The best kinetic model to describe the CoRuK/CNT catalyst is: 18.5 x 10 ^-5 PH2^0.39/ (1 + 7.2 10 ^-2 PCO^0.72 PH2^0.1)^2.

Endogenously generated H2S has been found not just a toxic substance but may play positive roles, such as the neuromodulator and vasorelaxant in the physiological system since 1990s. Then the precise control of the amount of Hydrogen Sulfide in the animal body raises great interests recently. However, the traditional methods for the Hydrogen Sulfide measurement need a large amount of tissue samples and take a complex procedure; it is impossible to develop any in-vivo real-time approach to measure H2S along the avenue of these methods. There is a great significance to develop new methods toward the measurement of Hydrogen Sulfide in in-vivo, real time, non- or less invasive manner with high resolution. One general idea to make the measurement less invasive is to take blood as sample i.e., to measure Hydrogen Sulfide in blood. <p>The study presented in this thesis aimed to conceive of new measurement methods for Hydrogen Sulfide in an aqueous solution along with their experimental verification. Though the blood sample will eventually be taken, the present study focused on an aqueous solution, which is a first step towards the final goal to measure Hydrogen Sulfide in blood. The study conducted a thorough literature review, resulting in the proposal of five methods, including: (i) the Hydrogen Sulfide measurement by Atomic Force Microscopy, (ii) the H2S measurement by Raman spectroscopy directly, (iii) the Hydrogen Sulfide measurement by Gas Chromatography/Mass Spectroscopy directly (with the static headspace technique), (iv) the Hydrogen Sulfide measurement by Mass Spectroscopy with Carbon Nanotubes, and (v) the Hydrogen Sulfide measurement by Raman spectroscopy with Carbon Nanotubes. The experiments for each of these methods were carried out, and the results were analyzed. Consequently, this study shows that method (v) is very promising to measure low concentration Hydrogen Sulfide in an aqueous solution, especially with the concentration level down to 10 μM and the presence of a linear relationship between the Hydrogen Sulfide concentration and its luminescent intensity.

Bovine respiratory disease complex is the most common disease that causes sig-nificant economic loss, typically in feedlot cattle. Current treatment methods are focused on reducing inflammatory responses, control of airway reactivity and improvement of pulmonary functions without potential side effects. Neutrophils are the key contributors in acute lung inflammation. However, activated neutrophils live longer and cause exces-sive tissue damage upon migration into lungs. Therefore, modulation of their migration and lifespan are attractive approaches in treatment strategies of bovine respiratory dis-ease. Nanotechnology holds significant potential to design new compounds by our ability to manipulate at the nanoscale. Helical rosette nanotubes are a class of novel, biologi-cally inspired, water soluble and metal-free nanotubes. I used helical rosette nanotubes conjugated to arginine-glycine-aspartic acid (RGD-RNT) to study their effects on neu-trophil chemotaxis, cell signaling and apoptosis. Bovine neutrophils exposed to 5% RGD-RNT reduced their migration in response to fMLP (formyl-Methionyl-Leucyl-Phenylalanine), compared to the non-treated group (P<0.001). This inhibitory effect was the same as that of groups treated with ERK1/2 inhibitor (UO126) and p38 MAPK in-hibitor (SB239063). In addition, the phosphorylated ERK1/2 and p38 MAPK for the first time were quantified by sandwich ELISA to elucidate the mechanism of neutrophil mi-gration. The phosphorylation of both the ERK1/2 and p38 was inhibited at 5 minutes by RGD-rosette nanotubes (P<0.05). Furthermore, integrin ÑvÒ3 is possibly involved in mi-gration of bovine neutrophils. Moreover, RGD-RNT did not induce apoptosis of bovine neutrophils which was inversed by pre-exposing them to LPS for 30 minutes (P<0.001). These experiments provide the first evidence that RGD-rosette nanotubes suppress phos-phorylation of ERK1/2 and p38 MAPK and inhibit chemotaxis of bovine neutrophils.

Optical transition energies are widely used for providing experimental insight into the electronic band structure of single-wall carbon nanotubes (SWCNTs). While the first and second optical transitions in semiconducting carbon nanotubes have already been heavily studied, due to experimental difficulties in accessing the relevant excitation energy region, little is known about higher lying transitions. Here, I present measurements of the third and fourth optical transitions of small-diameter (0.7-1.2 nm), semiconducting single-wall carbon nanotubes via resonant Raman spectroscopy in the visible deep blue region (415-465 nm) and photoluminescence excitation spectroscopy in the ultraviolet and visible blue optical regions (280-488 nm). Diameter-dependent Raman radial breathing mode features, as well as resonant energy excitation maxima determined by Raman and photoluminescence measurements, are assigned to specific (n,m) nanotube species. The Raman intensity within a given 2n+m branch is found to increase with decreasing chiral angle, consistent with similar measurements for lower order optical states. Additionally, increased excitation line widths and weaker Raman intensities are observed as higher lying transitions are accessed for a given nanotube, in agreement with previous Raman measurements. Chiefly, a scaling law analysis that removes the chiral-angle-dependent contribution to the optical transition energy indicates that the third and fourth transition energies exhibit a significant deviation from the energy trend line observed for the first and second optical transitions, when the transition energies are plotted as a function of nanotube diameter. This deviation can be understood in the context of a change in the competition between exchange and excitonic correction terms. Furthermore, for semiconducting SWCNTs with diameters less than 0.9 nm, an additional deviation is observed that is interpreted as the first observation of crossing-over of the third and fourth transition energy trend lines for a given 2n+m branch and a chirality dependence in the many-body excitonic effects that becomes significant at high nanotube curvatures.

Los nanotubos de carbono (CNTs, carbon nanotubes) son moléculas tubulares cuyo diámetro es de escala nanométrica y cuyas paredes están formadas por capas monoatómicas de carbono. Su estructura en combinación con su morfología unidimensional confieren unas propiedades muy especiales que hacen de los CNTs un material muy atractivo para el desarrollo de amplia gama de aplicaciones. En el marco de la micro y nanotecnología, los CNTs son un material muy prometedor para la fabricación de dispositivos y sistemas, por ejemplo, en el campo de la nanoelectrónica, los sensores o los sistemas nanoelectromecánicos (NEMS, del inglés nanoeletcromechanical systems). Sin embargo, dado que aún no se han estandarizado procesos para su síntesis controlada, su integración sigue siendo un reto. Esta tesis fue concebida para avanzar en la integración CNTs en distintos micro y nanodispositivos. El trabajo realizado aborda la ingeniería de procesos, el diseño de dispositivos, y la fabricación y la caracterización de esos dispositivos. Se plantearon dos objetivos principales. El primero fue el adquirir el conocimiento de la síntesis de CNTs mediante la técnica de depósito químico desde fase vapor por calentamiento rápido (RTCVD, rapid termal chemical vapour deposition) y desarrollar procesos para la síntesis de CNTs de una estructura concreta y en una determinada configuración. El segundo objetivo fue el desarrollo de procesos de fabricación para la integración de CNTs en dispositivos basados en diferentes tecnologías y con diferentes funcionalidades. A pesar de la problemática inherente al desarrollo de los procesos tecnológicos, se cumplieron la mayor parte de los objetivos inicialmente propuestos. La síntesis de CNTs se logró mediante catalizadores convencionales (principalmente hierro y níquel) y mediante catalizadores no convencionales (platino). Cabe destacar que los procesos de síntesis de CNTs fueron estandarizados a nivel de obleas de 4 pulgadas, tanto para configuraciones de baja densidad de CNTs monocapa (SWCNTs, single-walled carbon nanotubes) como para configuraciones de alta densidad de CNTs multicapa (MWCNTs, multi-walled carbon nanotubes), ya que la síntesis tradicionalmente se realiza a nivel de chip. En cuanto a la integración de CNTs, se optimizaron dos procesos principalmente. Por un lado, se desarrolló una tecnología para la fabricación masiva en oblea de transistores basados en SWCNTs. Mediante esta tecnología se logró la fabricación de 10.000 transistores funcionales en obleas de 4 pulgadas. Por otro lado, se integró gran densidad de MWCNTs sobre los electrodos metálicos de dispositivos que habían sido demostrados para detección bio-electroquímica. La caracterización de estos electrodos demostró que esta actualización de la tecnología mejora el rendimiento de la fabricación y las características electroquímicas de los electrodos respecto a los diseños anteriores. Los resultados presentados en esta tesis son un paso adelante para la Integración a muy gran escala (VLSI, very large system integration) de CNTs. Los procesos que se desarrollaron son de interés en el campo de la nanoelectrónica, en el campo de la bio-sensores electroquímicos, para la fabricación de dispositivos optoelectrónicos y para la fabricación de NEMS. / Carbon nanotubes (CNTs) are tubular molecules which diameters may be smaller than one nanometre and which walls are formed of single carbon atom layers that are arranged in a honey comb lattice. Because of their one dimensional aspect ratio and properties, which are conferred by their structural arrangement, CNTs are a very attractive material for a wide range of applications. In the frame of micro- and nanotechnology, CNTs have been demonstrated to be very promising for the fabrication of devices and systems for nanoelectronics, sensors or nanoelectromechanical systems (NEMS). However, standardised processes for their fully controlled synthesis and their successful integration into those systems are still challenging. This thesis was conceived to advance on the wafer scale integration of CNTs into micro- and nanodevices. Performed work dealt with process engineering, device design, device fabrication and device characterization. Two major goals were pursued: (i) to acquire the knowhow on the synthesis of CNTs by rapid thermal chemical vapour deposition (RTCVD) to develop recipes to synthesize certain in structure CNTs and certain in morphology CNT arrays, and (ii) the wafer scale integration of CNTs into devices with different functionalities and technological processes by conventional fabrication steps. Despite the inherent problematic of the technological process developments, most of the initially foreseen goals were fulfilled. The CNT synthesis was achieved by conventional (mainly iron and nickel) and by nonconventional (platinum) catalyst materials. It is remarkable how the CNT RTCVD synthesis processes were standardized at 4 inch wafer scale for either low density of single-walled (SW) CNT arrays or for dense, vertically aligned multi-walled (MW) CNT arrays, since the CNT synthesis is normally performed at chip level. Regarding the wafer scale integration of the CNTs, two main processes were optimised. On the one side, SWCNTs were integrated in the fabrication of CNT-FETs. This technology resulted in the fabrication of 10,000 functional CNT-FETs on 4 inch wafers in a sole fabrication process. Later on, the technology was upgraded for the fabrication of passivated CNT-FET devices for electrochemical sensing. On the other side, dense arrays of MWCNTs were integrated into devices based on metallic electrodes that had previously been demonstrated for bio-electrochemical sensing. These electrodes were demonstrated to improve the fabrication yield and the electrochemical characteristics with respect to the previous designs. Presented in this thesis results are a step forward to the Very Large Scale Integration (VLSI) of CNTs. The developed processes are of interest in the field of nanoelectronics, in the field of bio-electrochemical sensing, for the fabrication of optoelectronic devices and for the fabrication NEMS.