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Sample records for carbon nanotube growth

  1. Carbon nanotube growth density control

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  2. Templated Growth of Carbon Nanotubes

    Science.gov (United States)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  3. Carbon nanotube growth by PECVD: a review

    Energy Technology Data Exchange (ETDEWEB)

    Meyyappan, M; Delzeit, Lance; Cassell, Alan; Hash, David [NASA Ames Research Center, Moffett Field, CA 94035 (United States)

    2003-05-01

    Carbon nanotubes (CNTs), due to their unique electronic and extraordinary mechanical properties, have been receiving much attention for a wide variety of applications. Recently, plasma enhanced chemical vapour deposition (PECVD) has emerged as a key growth technique to produce vertically-aligned nanotubes. This paper reviews various plasma sources currently used in CNT growth, catalyst preparation and growth results. Since the technology is in its early stages, there is a general lack of understanding of growth mechanisms, the role of the plasma itself, and the identity of key species responsible for growth. This review is aimed at the low temperature plasma research community that has successfully addressed such issues, through plasma and surface diagnostics and modelling, in semiconductor processing and diamond thin film growth.

  4. Increased Alignment in Carbon Nanotube Growth

    Science.gov (United States)

    Delzeit, Lance D. (Inventor)

    2007-01-01

    Method and system for fabricating an array of two or more carbon nanotube (CNT) structures on a coated substrate surface, the structures having substantially the same orientation with respect to a substrate surface. A single electrode, having an associated voltage source with a selected voltage, is connected to a substrate surface after the substrate is coated and before growth of the CNT structures, for a selected voltage application time interval. The CNT structures are then grown on a coated substrate surface with the desired orientation. Optionally, the electrode can be disconnected before the CNT structures are grown.

  5. Carbon nanotubes: controlled growth and application

    Directory of Open Access Journals (Sweden)

    Chang Liu

    2013-01-01

    Full Text Available Notable progress has been made on the synthesis, properties and uses of carbon nanotubes (CNTs in the past two decades. However, the controlled growth of single-wall CNTs (SWCNTs with predefined and uniform structures remains a big challenge, and making full use of CNTs in applications still requires great effort. In this article, our strategies and recent progress on the controlled synthesis of SWCNTs by chemical vapor deposition are reviewed, and the applications of CNTs in lithium-ion batteries, transparent conductive films, and as connectors of metal atomic chains are discussed. Finally, future prospects for CNTs are considered.

  6. Continuous Growth of Vertically Aligned Carbon Nanotubes Forests

    OpenAIRE

    Guzman de Villoria, Roberto; Wardle, Brian L.

    2011-01-01

    Vertically aligned carbon nanotubes are one of the most promising materials due their numerous applications in flexible electronic devices, biosensors and multifunctional aircraft materials, among others. However, the costly production of aligned carbon nanotubes, generally in a batch process, prevents their commercial use. For the first time, a controlled process to grow aligned carbon nanotubes in a continuous manner is presented. Uniform growth is achieved using 2D and 3D substrates. A sig...

  7. Controlling growth of aligned carbon nanotubes from porous silicon templates

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Fabricating well-aligned carbon nanotubes, especially, on a silicon substrate is very important for their applications. In this paper, an aligned carbon nanotube array has been prepared by pyrolysis of hydrocarbons catalyzed by nickel nanoparticles embedded in porous silicon (PS) templates. High-magnification transmission electron microscopy images confirm that the nanotubes are well graphitized. The PS substrates with pore sizes between 10 and 100 nm play a control role on the growth of carbon nanotubes and the diameters of the tubes increase with the enlargement of the pores of the substrates. However, such a control role cannot be found in the macro-PS substrates.

  8. Catalytic growth of carbon nanotubes with large inner diameters

    Directory of Open Access Journals (Sweden)

    WEI REN ZHONG

    2005-02-01

    Full Text Available Carbon nanotubes (2.4 g/g catalyst, with large inner diameters were successfully synthesized through pyrolysis of methane on a Ni–Cu–Al catalyst by adding sodium carbonate into the carbon nanotubes growth system. The inner diameter of the carbon nanotubes prepared by this method is about 20–60 nm, while their outer diameter is about 40–80 nm. Transmission electron microscopy and X-ray diffraction were employed to investigate the morphology and microstructures of the carbon nanotubes. The analyses showed that these carbon nanotubes have large inner diameters and good graphitization. The addition of sodium carbonate into the reaction system brings about a slight decrease in the methane conversion and the yield of carbon. The experimental results showed that sodium carbonate is a mildly toxic material which influenced the catalytic activity of the Ni–Cu–Al catalyst and resulted in the formation of carbon nanotubes with large inner diameters. The growth mechanism of the carbon nanotubes with large inner diameters is discussed in this paper.

  9. Collective mechanochemical growth of carbon nanotubes

    Science.gov (United States)

    Bedewy, Mostafa M. K. M. A.

    Hierarchically ordered carbon nanotubes (CNTs) are promising for integration in high-performance structural composites, electrical interconnects, thermal interfaces, and filtration membranes. These and other applications require CNTs that are monodisperse, well aligned, and densely packed. Moreover, because more than 1 billion CNTs per square centimeter grow simultaneously in a typical chemical vapor deposition (CVD) process, understanding the collective chemical and mechanical effects of growth is key to engineering the properties of CNT-based materials. This dissertation presents tailored synthesis processes, characterization techniques, and mathematical models that enable improved control of the morphology of as-grown CNT "forests.". First, a comprehensive characterization methodology, combining synchrotron X-ray scattering and attenuation with real-time height kinetics, enabled mapping the spatiotemporal evolution of CNT diameter distribution, alignment and density. By this method, the forest mass kinetics were measured and found to follow the S-shaped Gompertz curve of population growth. Dividing a forest into subpopulations revealed size-dependent activation-deactivation competition. Additionally, in situ transmission electron microscopy (TEM) showed that the kinetics of CNT nucleation are S-shaped. Based on these findings, a collective growth model is proposed, wherein randomly oriented CNTs first nucleate then self-organize and lift-off during a crowding stage, followed by a density decay stage until self-termination when the density drops below the self-supporting threshold. Next, further X-ray data analysis enabled modeling the mechanics of entangled CNTs and proved that mechanical coupling is not only responsible for the self-organization into the aligned morphology, but is also an important limiting mechanism as significant forces ensue from diameter-dependent CNT growth rates. A custom-built CVD system was used for mechanical manipulation of growing

  10. Selective growth of carbon nanotube on silicon substrates

    Institute of Scientific and Technical Information of China (English)

    ZOU Xiao-ping; H. ABE; T. SHIMIZU; A. ANDO; H. TOKUMOT; ZHU Shen-ming; ZHOU Hao-shen

    2006-01-01

    The carbon nanotube (CNT) growth of iron oxide-deposited trench-patterns and the locally-ordered CNT arrays on silicon substrate were achieved by simple thermal chemical vapor deposition(STCVD) of ethanol vapor. The CNTs were uniformly synthesized with good selectivity on trench-patterned silicon substrates. This fabrication process is compatible with currently used semiconductor-processing technologies,and the carbon-nanotube fabrication process can be widely applied for the development of electronic devices using carbon-nanotube field emitters as cold cathodes and can revolutionize the area of field-emitting electronic devices. The site-selective growth of CNT from an iron oxide nanoparticle catalyst patterned were also achieved by drying-mediated self-assembly technique. The present method offers a simple and cost-effective method to grow carbon nanotubes with self-assembled patterns.

  11. The growth of carbon nanotubes on montmorillonite and zeolite (clinoptilolite)

    Energy Technology Data Exchange (ETDEWEB)

    Kadlecikova, M. [Department of Microelectronics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Breza, J. [Department of Microelectronics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia)], E-mail: juraj.breza@stuba.sk; Jesenak, K.; Pastorkova, K.; Luptakova, V. [Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska Dolina, 842 15 Bratislava (Slovakia); Kolmacka, M.; Vojackova, A. [Department of Microelectronics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Michalka, M. [International Laser Centre, Ilkovicova 3, 812 19 Bratislava (Slovakia); Vavra, I. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska Cesta 9, 841 04 Bratislava (Slovakia); Krizanova, Z. [Department of Microelectronics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia)

    2008-06-15

    Synthesis of carbon nanotubes described in the present work is based on activation of methane in a hot filament CVD reactor and subsequent creation of nanostructures on a catalyst pre-treated polished surface of silicon. An essential step of the synthesis is the use of natural minerals as catalysts. We have studied the catalyst parameters, the way of its application and the amount of Fe{sup 3+} cations on the surface of aluminosilicates on the quality of the grown nanotube layers. The growth of carbon nanotubes catalyzed by montmorillonite and zeolite (clinoptilolite) was confirmed by scanning electron microscopy and Raman spectroscopy.

  12. The growth of carbon nanotubes on montmorillonite and zeolite (clinoptilolite)

    Science.gov (United States)

    Kadlečíková, M.; Breza, J.; Jesenák, K.; Pastorková, K.; Luptáková, V.; Kolmačka, M.; Vojačková, A.; Michalka, M.; Vávra, I.; Križanová, Z.

    2008-06-01

    Synthesis of carbon nanotubes described in the present work is based on activation of methane in a hot filament CVD reactor and subsequent creation of nanostructures on a catalyst pre-treated polished surface of silicon. An essential step of the synthesis is the use of natural minerals as catalysts. We have studied the catalyst parameters, the way of its application and the amount of Fe 3+ cations on the surface of aluminosilicates on the quality of the grown nanotube layers. The growth of carbon nanotubes catalyzed by montmorillonite and zeolite (clinoptilolite) was confirmed by scanning electron microscopy and Raman spectroscopy.

  13. Kinetics of Laser-Assisted Carbon Nanotube Growth

    CERN Document Server

    van de Burgt, Yoeri; Mandamparambil, Rajesh

    2014-01-01

    Laser-assisted chemical vapour deposition (CVD) growth is an attractive mask-less process for growing locally aligned carbon nanotubes (CNTs) in selected places on temperature sensitive substrates. The nature of the localized process results in fast carbon nanotube growth with high experimental throughput. Here, we report on detailed investigation of growth kinetics related to physical and chemical process characteristics. Specifically, the growth kinetics is investigated by monitoring the dynamical changes of reflected laser beam intensity during growth. Benefiting from the fast growth and high experimental throughput, we investigate a wide range of experimental conditions and propose several growth regimes. Rate-limiting steps are determined using rate equations linked to the proposed growth regimes, which are further characterized by Raman spectroscopy and Scanning Electron Microscopy (SEM), therefore directly linking growth regimes to the structural quality of the CNTs. Activation energies for the differe...

  14. Thermodynamics behind carbon nanotube growth via endothermic catalytic decomposition reaction.

    Science.gov (United States)

    Harutyunyan, Avetik R; Kuznetsov, Oleg A; Brooks, Christopher J; Mora, Elena; Chen, Gugang

    2009-02-24

    Carbon filaments can be grown using hydrocarbons with either exothermic or endothermic catalytic decomposition enthalpies. By in situ monitoring the evolution of the reaction enthalpy during nanotube synthesis via methane gas, we found that although the decomposition reaction of methane is endothermic an exothermic process is superimposed which accompanies the nanotube growth. Analysis shows that the main contributor in this liberated heat is the radiative heat transfer from the surroundings, along with dehydrogenation reaction of in situ formed secondary hydrocarbons on the catalyst surface and the carbon hydrogenation/oxidation processes. This finding implies that nanotube growth process enthalpy is exothermic, and particularly, it extends the commonly accepted temperature gradient driven growth mechanism to the growth via hydrocarbons with endothermic decomposition enthalpy.

  15. Toward Controlled Growth of Helicity-Specific Carbon Nanotubes.

    Science.gov (United States)

    Santos, Elton J G; Nørskov, Jens K; Harutyunyan, Avetik R; Abild-Pedersen, Frank

    2015-06-18

    The underlying mechanisms for the nucleation of carbon nanotubes as well as their helicity, remain elusive. Here, using van der Waals dispersion force calculations implemented within density functional theory, we study the cap formation, believed to be responsible for the chirality of surface-catalyzed carbon nanotubes. We find the energetics associated with growth along different facets to be independent of the surface orientation and that the growth across an edge along the axis of the metal particle leads to a perfect honeycomb lattice in a curved geometry. The formation of defects in the graphene matrix, which bend the carbon plane, requires that two or more graphene embryos with significantly different growth axis merge. Such scenario is only possible at the front- or back-end of the metal particle where growth symmetry is broken. The graphene embryos reconstruct their hexagonal structure into pentagons, heptagons, and octagons counterpart to accommodate the tube curvature.

  16. Plasma Enhanced Growth of Carbon Nanotubes For Ultrasensitive Biosensors

    Science.gov (United States)

    Cassell, Alan M.; Li, J.; Ye, Q.; Koehne, J.; Chen, H.; Meyyappan, M.

    2004-01-01

    The multitude of considerations facing nanostructure growth and integration lends itself to combinatorial optimization approaches. Rapid optimization becomes even more important with wafer-scale growth and integration processes. Here we discuss methodology for developing plasma enhanced CVD growth techniques for achieving individual, vertically aligned carbon nanostructures that show excellent properties as ultrasensitive electrodes for nucleic acid detection. We utilize high throughput strategies for optimizing the upstream and downstream processing and integration of carbon nanotube electrodes as functional elements in various device types. An overview of ultrasensitive carbon nanotube based sensor arrays for electrochemical biosensing applications and the high throughput methodology utilized to combine novel electrode technology with conventional MEMS processing will be presented.

  17. Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs) in Ag-nanocrystal particles/carbon nanotubes (Ag-NCPs/CNTs) hybrid structures were reported. The growth of Ag-NCPs on multiwalled carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition. High-resolution transmission electron microscopy and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc). The growth of Ag-NCPs on MWCNTs induced the cross-section deformation of MWCNT. The experimental results also showed that the synthesized Ag-NCPs/CNTs hybrid structure appeared as quasi-one dimensional nanowires containing the Ag-NCP/CNT hetero-junction. There was local cross-section deformation on MWCNTs at the interface of hetero-junction. These results involve the important topic about fundamental and practical studies for structure of MNCPs on CNTs and also find clues to further research of Ag nanocrystal growing on MWCNTs and related Ag-CNT interaction.

  18. Stable colloidal Co-Pd nanocatalysts for carbon nanotube growth

    Energy Technology Data Exchange (ETDEWEB)

    Berenguer, A.; Golovko, V.B.; Johnson, B.F.G.; Robertson, John [Department of Chemistry, University of Cambridge (United Kingdom); Cantoro, M.; Hofmann, S.; Wirth, C.T. [Department of Engineering, University of Cambridge (United Kingdom)

    2009-12-15

    The standard preparation method for catalysts for surface-bound growth of carbon nanotubes (CNT) is to sputter or evaporate the metal catalyst (Fe, Co, and Ni) onto the surface. A lower cost method for large areas is to use liquid delivery. Colloids have the advantage of containing the catalyst in nanocluster form. Our previously developed colloidal catalysts were successful for growth but had limited shelf-life due to oxidation and coagulation. Here, we develop an air-stable colloidal catalyst with long shelf-life of many months to years. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  19. Epitaxial Growth of Aligned and Continuous Carbon Nanofibers from Carbon Nanotubes.

    Science.gov (United States)

    Lin, Xiaoyang; Zhao, Wei; Zhou, Wenbin; Liu, Peng; Luo, Shu; Wei, Haoming; Yang, Guangzhi; Yang, Junhe; Cui, Jie; Yu, Richeng; Zhang, Lina; Wang, Jiaping; Li, Qunqing; Zhou, Weiya; Zhao, Weisheng; Fan, Shoushan; Jiang, Kaili

    2017-02-28

    Exploiting the superior properties of nanomaterials at macroscopic scale is a key issue of nanoscience. Different from the integration strategy, "additive synthesis" of macroscopic structures from nanomaterial templates may be a promising choice. In this paper, we report the epitaxial growth of aligned, continuous, and catalyst-free carbon nanofiber thin films from carbon nanotube films. The fabrication process includes thickening of continuous carbon nanotube films by gas-phase pyrolytic carbon deposition and further graphitization of the carbon layer by high-temperature treatment. As-fabricated nanofibers in the film have an "annual ring" cross-section, with a carbon nanotube core and a graphitic periphery, indicating the templated growth mechanism. The absence of a distinct interface between the carbon nanotube template and the graphitic periphery further implies the epitaxial growth mechanism of the fiber. The mechanically robust thin film with tunable fiber diameters from tens of nanometers to several micrometers possesses low density, high electrical conductivity, and high thermal conductivity. Further extension of this fabrication method to enhance carbon nanotube yarns is also demonstrated, resulting in yarns with ∼4-fold increased tensile strength and ∼10-fold increased Young's modulus. The aligned and continuous features of the films together with their outstanding physical and chemical properties would certainly promote the large-scale applications of carbon nanofibers.

  20. Can amino-functionalized carbon nanotubes carry functional nerve growth factor?

    Institute of Scientific and Technical Information of China (English)

    Wen Chen; Qing Xiong; Quanxia Ren; Yake Guo; Gao Li

    2014-01-01

    Carbon nanotubes can carry protein into cells to induce biological effects. Amino-functionalized carbon nanotubes are soluble and biocompatible, have high reactivity and low toxicity, and can help promote nerve cell growth. In this study, amino-functionalized ethylenediamine-treated multi-walled carbon nanotubes were used to prepare carbon nanotubes-nerve growth factor complexes by non-covalent grafting. The physicochemical properties, cytotoxicity to PC12 and chick embryo dorsal root ganglion, and biological activity of the carbon nanotubes-nerve growth factor complexes were investigated. The results showed that amino functionalization improved carbon nanotubes-nerve growth factor complex dispersibility, reduced their toxicity to PC12 cells, and promoted PC12 cell differentiation and chick embryo dorsal root ganglion.

  1. Electric field effect in the growth of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, E., E-mail: ericvpp@gmail.com; Briceño-Fuenmayor, H. [Instituto Venezolano de Investigaciones Científicas (IVIC), Laboratorio de Física de Fluidos y Plasma (Venezuela, Bolivarian Republic of); Arévalo, J. [Instituto Zuliano de Investigaciones Tecnológicas (INZIT), Unidad de Caracterización y Estructura de Materiales (Venezuela, Bolivarian Republic of); Atencio, R. [Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Investigación y Tecnología de Materiales (Venezuela, Bolivarian Republic of); Corredor, L. [Instituto Zuliano de Investigaciones Tecnológicas (INZIT), Unidad de Caracterización y Estructura de Materiales (Venezuela, Bolivarian Republic of)

    2015-06-15

    The growth of carbon nanotubes (CNTs) under a controlled electric field in a chemical vapor deposition system is investigated. We evaluate the influence of this external field on the morphological and structural characteristics of CNTs. Scanning electron microscopy results display a large presence of carbonaceous material in the positive plate, which appear to be a consequence of the attraction of electric forces over the electronically unbalanced cracked carbon molecules in the heating zone. We also observe a growth behavior for CNTs, in which catalyst particles are localized either at the bottom or the upper part of the nanotube, depending on the intensity and direction of the electric field. A Raman analysis from all obtained carbon materials shows the presence of two peaks, corresponding to the D ∼ 1340 cm{sup −1} and G ∼ 1590 cm{sup −1} bands attributed to multiwall CNTs. The average diameter of the CNTs is in the range between 90 and 40 nm. These results provide experimental evidence for the dependence of the catalyst and subtract interaction on the growing mechanism, in which weak chemical or electronic interactions could stimulate a top-growing as the strongest base-growing process.

  2. Carbon nanotube growth activated by quantum-confined silicon nanocrystals

    Science.gov (United States)

    Mariotti, D.; Švrček, V.; Mathur, A.; Dickinson, C.; Matsubara, K.; Kondo, M.

    2013-03-01

    We report on the use of silicon nanocrystals (Si-ncs) to activate nucleation and growth of carbon nanotubes (CNTs) without using any metal catalyst. Si-ncs with different surface characteristics have been exposed to the same CH4 low-pressure plasma treatment producing quite different results. Specifically, Si-ncs prepared by laser ablation in water have contributed to the formation of micrometre-sized silicon spherical particles. On the other hand, Si-ncs prepared by electrochemical etching did not induce any specific growth while the third type of Si-ncs, prepared by electrochemical etching and treated by a laser fragmentation process, induced the growth of multi-walled CNTs. The different outcomes of the same plasma process are attributed to the diverse surface features presented by the Si-ncs.

  3. The Infinite Possible Growth Ambients that Support Single-Wall Carbon Nanotube Forest Growth

    Science.gov (United States)

    Kimura, Hiroe; Goto, Jundai; Yasuda, Satoshi; Sakurai, Shunsuke; Yumura, Motoo; Futaba, Don N.; Hata, Kenji

    2013-11-01

    We report the virtually infinite possible carbon feedstocks which support the highly efficient growth of single-wall carbon nanotubes (SWCNTs) using on the water-assisted chemical vapor deposition method. Our results demonstrate that diverse varieties of carbon feedstocks, in the form of hydrocarbons, spanning saturated rings (e.g. trans-deca-hydronaphthalene), saturated chains (e.g. propane), unsaturated rings (e.g. dicyclopentadiene), and unsaturated chains (e.g. ethylene) could be used as a carbon feedstocks with SWCNT forests with heights exceeding 100 ums. Further, we found that all the resultant SWCNTs possessed similar average diameter indicating that the diameter was mainly determined by the catalyst rather than the carbon feedstock within this synthetic system. A demonstration of the generality was the synthesis of a carbon nanotube forest from a highly unorthodox combination of gases where trans-decahydronaphthalene acted as the carbon feedstock and benzaldehyde acted as the growth enhancer.

  4. Computational studies of small carbon and iron-carbon systems relevant to carbon nanotube growth.

    Science.gov (United States)

    Duan, Haiming; Rosén, Arne; Harutyunyan, Avetik; Curtarolo, Stefano; Bolton, Kim

    2008-11-01

    Density functional theory (DFT) calculations show that dimers and longer carbon strings are more stable than individual atoms on Fe(111) surfaces. It is therefore necessary to consider the formation of these species on the metal surfaces and their effect on the mechanism of single-walled nanotube (SWNT) growth. The good agreement between the trends (energies and structures) obtained using DFT and those based on the Brenner and AIREBO models indicate that these analytic models provide adequate descriptions of the supported carbon systems needed for valid molecular dynamics simulations of SWNT growth. In contrast, the AIREBO model provides a better description of the relative energies for isolated carbon species, and this model is preferred over the Brenner potential when simulating SWNT growth in the absence of metal particles. However, the PM3 semiempirical model appears to provide an even better description for these systems and, given sufficient computer resources, direct dynamics methods based on this model may be preferred.

  5. Chirality-dependent vapor-phase epitaxial growth and termination of single-wall carbon nanotubes.

    Science.gov (United States)

    Liu, Bilu; Liu, Jia; Tu, Xiaomin; Zhang, Jialu; Zheng, Ming; Zhou, Chongwu

    2013-09-11

    Structurally uniform and chirality-pure single-wall carbon nanotubes are highly desired for both fundamental study and many of their technological applications, such as electronics, optoelectronics, and biomedical imaging. Considerable efforts have been invested in the synthesis of nanotubes with defined chiralities by tuning the growth recipes but the approach has only limited success. Recently, we have shown that chirality-pure short nanotubes can be used as seeds for vapor-phase epitaxial cloning growth, opening up a new route toward chirality-controlled carbon nanotube synthesis. Nevertheless, the yield of vapor-phase epitaxial growth is rather limited at the present stage, due in large part to the lack of mechanistic understanding of the process. Here we report chirality-dependent growth kinetics and termination mechanism for the vapor-phase epitaxial growth of seven single-chirality nanotubes of (9, 1), (6, 5), (8, 3), (7, 6), (10, 2), (6, 6), and (7, 7), covering near zigzag, medium chiral angle, and near armchair semiconductors, as well as armchair metallic nanotubes. Our results reveal that the growth rates of nanotubes increase with their chiral angles while the active lifetimes of the growth hold opposite trend. Consequently, the chirality distribution of a nanotube ensemble is jointly determined by both growth rates and lifetimes. These results correlate nanotube structures and properties with their growth behaviors and deepen our understanding of chirality-controlled growth of nanotubes.

  6. Single-Wall Carbon Nanotube Growth from Graphite Layers-a Tight Binding Molecular Dynamics Simulation

    Institute of Scientific and Technical Information of China (English)

    Yuntuan FANG; Min ZHU; Yongshun WANG

    2003-01-01

    The growth of single-wall carbon nanotube from graphite layers is studied by tight binding molecular dynamics simulation. Given temperature of 2500 K or 3500 K and an interval of 0.25 nm for the two layers of graphite, a single-wall carbon nanotube with a zigzag shell will be produced. On the other conditions the carbon nanotube cannot grow or grows with too many defects. All carbon nanotube ends have pentagons which play an important role during the tube ends closing.

  7. Direct growth of carbon nanotubes on hydroxyapatite using MPECVD

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M., E-mail: duraia_physics@yahoo.com [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farbi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, Almaty (Kazakhstan); Texas State University-San Marcos, Department of Chemistry and Biochemistry, 601 University Dr., San Marcos, TX 78666 (United States); Hannora, A. [Suez Canal University, Faculty of Petroleum and Mining Engineering (Egypt); Mansurov, Z. [Al-Farbi Kazakh National University, Almaty (Kazakhstan); Beall, Gary W. [Texas State University-San Marcos, Department of Chemistry and Biochemistry, 601 University Dr., San Marcos, TX 78666 (United States)

    2012-01-16

    Graphical abstract: Carbon nanotubes have been grown directly on hydroxyapatite by using microwave plasma-enhanced chemical vapor deposition (MPECVD). Highlights: Black-Right-Pointing-Pointer CNTs have been successfully grown directly on hydroxyapatite using MPECVD. Black-Right-Pointing-Pointer Diameter distribution of the CNTs lies in the range from 30 to 70 nm. Black-Right-Pointing-Pointer The HA surface is partially transformed to {beta}-TCP during the deposition. Black-Right-Pointing-Pointer Grown CNTs have good quality and I{sub G}/I{sub D} ratio lies between 1.243 and 1.774. - Abstract: For the first time carbon nanotubes (CNTs) have been successfully grown directly on hydroxyapatite (HA) by using microwave plasma enhanced chemical vapor deposition (MPECVD). Such integration has potential to capitalize on the merits of both HA and CNTs. This type of coating could be useful to improve the interface between bone and the implant. Scanning electron microscope SEM investigations show that; the surface of the CNTs is relatively clean and free of amorphous carbon. The CNTs diameters lie in the range 30-70 nm. In addition HA encapsulation by carbon was observed at a growth temperature 750 Degree-Sign C. Raman spectroscopy indicates that the CNTs are of high quality and the I{sub G}/I{sub D} ratio lies between 1.243 and 1.774. The changes in the X-ray diffraction (XRD) patterns give an indication that during the plasma deposition the HA-substrate surface is subjected to a temperature sufficient for partial conversion to the {beta}-tricalcium phosphate via dehydroxylation.

  8. Iron assisted growth of copper-tipped multi-walled carbon nanotubes.

    Science.gov (United States)

    Abrams, Z R; Szwarcman, D; Lereah, Y; Markovich, G; Hanein, Y

    2007-12-12

    Carbon nanotubes incorporating copper are highly sought after for nanoelectronic applications. Indeed, several recent studies have demonstrated the production of copper-tipped nanotubes using the chemical vapor deposition method. Here we present the growth and detailed characterization of such copper-tipped nanotubes. The nanotubes grown were of a 'bamboo-like' structure, consisting of stacked cups of graphene, and were produced by chemical vapor deposition employing iron and copper nanoparticles as a catalyst and metal source respectively. Transmission electron microscopy and electron holography analysis of the tips of these nanotubes revealed a small crystalline iron particle on the inner side of the copper tip, with the nanotube structure encapsulating the iron. This form of growth may allow the formation of similar structures with various other metal-tipped carbon nanotubes to be manufactured.

  9. Controlled growth and assembly of single-walled carbon nanotubes for nanoelectronics

    Science.gov (United States)

    Omrane, Badr

    Carbon nanotubes are promising candidates for enhancing electronic devices in the future at the nanoscale level. Their integration into today's electronics has however been challenging due to the difficulties in controlling their orientation, location, chirality and diameter during formation. This thesis investigates and develops new techniques for the controlled growth and assembly of carbon nanotubes as a way to address some of these challenges. Colloidal lithography using nanospheres of 450 nm in diameter, acting as a shadow mask during metal evaporation, has been used to pattern thin films of single-walled carbon nanotube multilayer catalysts on Si and Si/SiO2 substrates. Large areas of periodic hexagonal catalyst islands were formed and chemical vapor deposition resulted in aligned single-walled carbon nanotubes on Si substrates within the hexagonal array of catalyst islands. On silicon dioxide, single-walled carbon nanotubes connecting the hexagonal catalyst islands were observed. To help explain these observations, a growth model based on experimental data has been used. Electrostatic interaction, van der Waals interaction and gas flow appear to be the main forces contributing to single-walled carbon nanotube alignment on Si/SiO2. Although the alignment of single-walled carbon nanotubes on Si substrates is still not fully understood, it may be due to a combination of the above factors, in addition to silicide-nanotube interaction. Atomic force microscopy and Raman spectroscopy of the post-growth samples show single-walled carbon nanotubes of 1-2 nm in diameter. Based on the atomic force microscopy data and Raman spectra, a mixture of individual and bundles of metallic and semiconducting nanotubes were inferred to be present. A novel technique based on direct nanowriting of carbon nanotube catalysts in liquid form has also been developed. The reliability of this method to produce nanoscale catalyst geometries in a highly controlled manner, as required for

  10. Anodic aluminium oxide membranes used for the growth of carbon nanotubes.

    Science.gov (United States)

    López, Vicente; Morant, Carmen; Márquez, Francisco; Zamora, Félix; Elizalde, Eduardo

    2009-11-01

    The suitability of anodic aluminum oxide (AAO) membranes as template supported on Si substrates for obtaining organized iron catalyst for carbon nanotube (CNT) growth has been investigated. The iron catalyst was confined in the holes of the AAO membrane. CVD synthesis with ethylene as carbon source led to a variety of carbon structures (nanotubes, helices, bamboo-like, etc). In absence of AAO membrane the catalyst was homogeneously distributed on the Si surface producing a high density of micron-length CNTs.

  11. Carbon nanotubes instruct physiological growth and functionally mature syncytia: nongenetic engineering of cardiac myocytes.

    Science.gov (United States)

    Martinelli, Valentina; Cellot, Giada; Toma, Francesca Maria; Long, Carlin S; Caldwell, John H; Zentilin, Lorena; Giacca, Mauro; Turco, Antonio; Prato, Maurizio; Ballerini, Laura; Mestroni, Luisa

    2013-07-23

    Myocardial tissue engineering currently represents one of the most realistic strategies for cardiac repair. We have recently discovered the ability of carbon nanotube scaffolds to promote cell division and maturation in cardiomyocytes. Here, we test the hypothesis that carbon nanotube scaffolds promote cardiomyocyte growth and maturation by altering the gene expression program, implementing the cell electrophysiological properties and improving networking and maturation of functional syncytia. In our study, we combine microscopy, biological and electrophysiological methodologies, and calcium imaging, to verify whether neonatal rat ventricular myocytes cultured on substrates of multiwall carbon nanotubes acquire a physiologically more mature phenotype compared to control (gelatin). We show that the carbon nanotube substrate stimulates the induction of a gene expression profile characteristic of terminal differentiation and physiological growth, with a 2-fold increase of α-myosin heavy chain (P carbon nanotubes appear to exert a protective effect against the pathologic stimulus of phenylephrine. Finally, cardiomyocytes on carbon nanotubes demonstrate a more mature electrophysiological phenotype of syncytia and intracellular calcium signaling. Thus, carbon nanotubes interacting with cardiomyocytes have the ability to promote physiological growth and functional maturation. These properties are unique in the current vexing field of tissue engineering, and offer unprecedented perspectives in the development of innovative therapies for cardiac repair.

  12. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, S A; Baumann, T F; Kong, J; Satcher, J H; Dresselhaus, M S

    2007-02-15

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  13. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Science.gov (United States)

    Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.

    2007-02-20

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  14. Laser-assisted growth of carbon nanotubes - A review

    NARCIS (Netherlands)

    Burgt, Y. van de

    2014-01-01

    Laser-assisted chemical vapor deposition (LACVD) is an attractive maskless process for growing locally carbon nanotubes at selected places on substrates that may contain temperature-sensitive components. This review gives a comprehensive overview of the reported research with respect to laser assist

  15. Growth of straight carbon nanotubes by simple thermal chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    ZOU Xiao-ping; H. ABE; T. SHIMIZU; A. ANDO; H. TOKUMOTO; ZHU Shen-ming; ZHOU Hao-shen

    2006-01-01

    Straight carbon nanotubes (CNTs) were achieved by simple thermal chemical vapor deposition(STCVD) catalyzed by Mo-Fe alloy catalyst on silica supporting substrate at 700 ℃. High-resolution transmission electron microscopy images show that the straight CNTs are well graphitized with no attached amorphous carbon. Mo-Fe alloy catalyst particles play a very crucial role in the growth of straight CNTs. The straight carbon nanotubes contain much less defects than the curved nanotubes and might have potential applications for nanoelectrical devices in the future. The simple synthesis of straight CNTs may have benefit for large-scale productions.

  16. Growth of single-walled gold nanotubes confined in carbon nanotubes, studied by molecular dynamics simulations

    Science.gov (United States)

    Han, Yang; Hu, Ting; Dong, Jinming

    2013-01-01

    Growth of the single-walled gold nanotube (SWGNT), confined in the single-walled carbon nanotube (SWCNT) has been studied by using the classical molecular dynamics (MD) simulations, in which two different empirical potentials (the glue and EAM potentials) are used for the interaction between gold atoms. It is found that under the glue potential, three new SWGNTs, (3, 2), (4, 2) and (6, 3) gold tubes can be formed, in addition to the previously found (3, 3), (4, 3) and (5, 3) ones, among which two achiral ones, (4, 2) and (6, 3) gold tubes are particularly interesting because they were thought to be not the tube-like structures, or to have large enough diameter, permitting an extra gold atom chain in it. However, when the EAM potential is used, only four SWGNTs, i.e., (3, 2), (4, 2), (4, 3) and (5, 3) gold tubes could be formed in our MD simulations. After comparing all the MD simulation results with those of the first principles calculations, it is found that the EAM potential is better to describe the interaction between gold atoms than the glue potential for the MD simulation on the growth of gold tubular structure in confined CNT.

  17. Growth of chiral single-walled carbon nanotube caps in the presence of a cobalt cluster

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Gualdron, Diego A; Balbuena, Perla B [Department of Chemical Engineering, Texas A and M University, College Station, TX 77843 (United States)], E-mail: balbuena@tamu.edu

    2009-05-27

    Density functional theory is used to simulate nanotube growth by addition of a pair of carbon atoms to a composite chiral nanotube cap/cobalt cluster system, with caps corresponding to near-armchair (6, 5), (7, 5) and near-zigzag (9, 1) nanotubes. Two different carbon addition processes are evaluated: in the first, the new carbon atoms are located in the vicinity of the armchair site of the cap rim, and thus this process provides insight into the root-growth mechanism; in the second the carbon atoms are initially located under the cobalt cluster, and thus this process helps one to evaluate the dissolution of carbon inside the metal cluster. The geometric evolution and energetics of the system are used to explain features of the mechanism of nanotube growth. The root-growth reaction is shown to occur by displacement of a cobalt atom initially interacting with the armchair site while the added carbon atoms bond to each other forming a new hexagonal ring, whereas the carbon dissolution process shows formation of dimers inside the cluster only for the (6, 5) system. The energetics for both steps reveals that the dissolution stage is probably controlling the overall nanotube growth rate.

  18. Growth of chiral single-walled carbon nanotube caps in the presence of a cobalt cluster.

    Science.gov (United States)

    Gómez-Gualdrón, Diego A; Balbuena, Perla B

    2009-05-27

    Density functional theory is used to simulate nanotube growth by addition of a pair of carbon atoms to a composite chiral nanotube cap/cobalt cluster system, with caps corresponding to near-armchair (6, 5), (7, 5) and near-zigzag (9, 1) nanotubes. Two different carbon addition processes are evaluated: in the first, the new carbon atoms are located in the vicinity of the armchair site of the cap rim, and thus this process provides insight into the root-growth mechanism; in the second the carbon atoms are initially located under the cobalt cluster, and thus this process helps one to evaluate the dissolution of carbon inside the metal cluster. The geometric evolution and energetics of the system are used to explain features of the mechanism of nanotube growth. The root-growth reaction is shown to occur by displacement of a cobalt atom initially interacting with the armchair site while the added carbon atoms bond to each other forming a new hexagonal ring, whereas the carbon dissolution process shows formation of dimers inside the cluster only for the (6, 5) system. The energetics for both steps reveals that the dissolution stage is probably controlling the overall nanotube growth rate.

  19. Decorating multiwalled carbon nanotubes with zinc oxide nano-crystallines through hydrothermal growth process

    Institute of Scientific and Technical Information of China (English)

    LI ChenSha; QIAO YingJie; LI YuMing

    2012-01-01

    Multiwalled-carbon nanotubes coated with nano-crystalline zinc oxide (ZnO) was prepared by in situ growth of nano zinc oxide on the surfaces of carbon nanotubes through hydrothermal method.X-ray diffraction,transmission electron microscopy and scanning electron microscopy analysis techniques were used to characterize the samples.It was observed that a layer of nano-crystalline ZnO with the wurtzite hexagonal crystal structure was uniformly coated on the nanotube surfaces with good adhesion,which resulted in the formation of a novel ZnO-nanotube nano composite.In this work,the carbon nanotubes decorated by metal oxide nanoparticles were synthesized by a simple chemical-solution route which is suitable for the large-scale production with low cost.

  20. A vapor-liquid-solid model for chemical vapor deposition growth of carbon nanotubes.

    Science.gov (United States)

    Jiang, Kaili; Feng, Chen; Liu, Kai; Fan, Shoushan

    2007-01-01

    Although carbon nanotubes (CNTs) with a variety of morphologies have been successfully synthesized, there is no clear physical picture of the growth process. Correspondingly, the growth mechanism is still not clear up to now. Here we suggest a VLS model for the growth process of CNTs, which involves a liquid or liquid-like state catalyst. The basic idea is that, due to the high thermal conductivity and nanometer size of the catalyst and the fast diffusion of carbon atoms in it, both the temperature and the carbon atom distribution across it are uniform. The supersaturation level can be expressed as a function of the carbon concentration and temperature, which determines the nucleation dynamics and growth kinetics. Based on this model, the growth rate equation was obtained to describe the growth kinetics of carbon nanotubes, which shows good accordance with the experimental results.

  1. Phase stability of iron-carbon nanocarbides and implications for the growth of carbon nanotubes

    Science.gov (United States)

    Awasthi, Neha

    Catalyst nanoparticles play a crucial role in the synthesis of single-walled carbon nanotubes by chemical vapor deposition technique. Understanding the thermal behavior of the nano-catalysts, their interaction with Carbon and stability of nanocarbides can give better insight into the growth mechanism and control over selective, yield of nanotubes. In this work, we present results using first-principle calculations and classical molecular dynamics simulations to understand the thermodynamics of free and Al2O3 supported Fe-C nanoparticles. We observe that the substrate plays an important role during the growth reaction by increasing the melting temperatures of small and medium size Fe nanoparticles. We investigate Fe-C phase diagrams for small Fe nanoparticles (d˜2nm) and discover that as the size of the Fe nanoparticle is reduced, the eutectic point shifted significantly toward lower temperatures, as expected from the Gibbs-Thomson law, and also toward lower concentrations of C. We devise a simple model based on the Young-Laplace pressure-radius relation, to predict the behavior of the phases competing for stability in Fe-C nanoclusters at low temperature. We identify ranges of nanoparticle sizes which are compatible for steady state-, limited- and no-growth of SWCNTs corresponding to unaffected, reduced and no solubility of C in the Fe nanoparticles. We also calculate Fe-Mo-C ternary phase diagrams to investigate the behavior of bimetallic Fe:Mo catalyst nanoparticles. Our results show that addition of Mo (upto small concentrations) lowers the minimum radius when stable carbides nucleate and poison the catalyst, which enables a larger range of catalyst nanoparticles sizes to nucleate nanotubes. We also find that pure Fe has the highest surface concentration in Fe:Mo nanoparticles and is likely to be the active nucleation site for nanotubes.

  2. Revealing the Impact of Catalyst Phase Transition on Carbon Nanotube Growth by in Situ Raman Spectroscopy

    Science.gov (United States)

    2013-01-01

    Carbon Nanotube Growth Termina- tion. J. Phys. Chem. Lett. 2010, 1, 918–922. 25. Kamat, P. V. Graphene-Based Nanoarchitectures. Anchor- ing Semiconductor ...1980, 51, 4813–4816. 35. Xiang, Q.; Yu, J.; Jaroniec, M. Synergetic Effect of MoS2 and Graphene as Cocatalysts for Enhanced Photocatalytic H2

  3. Miniaturized reaction chamber for optimized laser-assisted carbon nanotube growth

    NARCIS (Netherlands)

    Burgt, Y. van de; Loon, W. van; Mandamparambil, R.; Bellouard, Y.

    2014-01-01

    The localized growth of carbon nanotube structures has potential in many applications such as interconnects, field emitters and sensors. Using a laser to locally heat the substrate offers a highly versatile process compatible with a broad range of substrates and devices. However, for laser-assisted

  4. Carbon nanotube-based sensor and method for detection of crack growth in a structure

    Science.gov (United States)

    Smits, Jan M. (Inventor); Kite, Marlen T. (Inventor); Moore, Thomas C. (Inventor); Wincheski, Russell A. (Inventor); Ingram, JoAnne L. (Inventor); Watkins, Anthony N. (Inventor); Williams, Phillip A. (Inventor)

    2007-01-01

    A sensor has a plurality of carbon nanotube (CNT)-based conductors operatively positioned on a substrate. The conductors are arranged side-by-side, such as in a substantially parallel relationship to one another. At least one pair of spaced-apart electrodes is coupled to opposing ends of the conductors. A portion of each of the conductors spanning between each pair of electrodes comprises a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis. Because a direct correlation exists between the resistance of a carbon nanotube and its strain, changes experienced by the portion of the structure to which the sensor is coupled induce a corresponding change in the electrical properties of the conductors, thereby enabling detection of crack growth in the structure.

  5. Growth, modification and integration of carbon nanotubes into molecular electronics

    Science.gov (United States)

    Moscatello, Jason P.

    Molecules are the smallest possible elements for electronic devices, with active elements for such devices typically a few Angstroms in footprint area. Owing to the possibility of producing ultra-high density devices, tremendous effort has been invested in producing electronic junctions by using various types of molecules. The major issues for molecular electronics include (1) developing an effective scheme to connect molecules with the present micro- and nano-technology, (2) increasing the lifetime and stabilities of the devices, and (3) increasing their performance in comparison to the state-of-the-art devices. In this work, we attempt to use carbon nanotubes (CNTs) as the interconnecting nanoelectrodes between molecules and microelectrodes. The ultimate goal is to use two individual CNTs to sandwich molecules in a cross-bar configuration while having these CNTs connected with microelectrodes such that the junction displays the electronic character of the molecule chosen. We have successfully developed an effective scheme to connect molecules with CNTs, which is scalable to arrays of molecular electronic devices. To realize this far reaching goal, the following technical topics have been investigated. (1) Synthesis of multi-walled carbon nanotubes (MWCNTs) by thermal chemical vapor deposition (T-CVD) and plasma-enhanced chemical vapor deposition (PECVD) techniques (Chapter 3). We have evaluated the potential use of tubular and bamboo-like MWCNTs grown by T-CVD and PE-CVD in terms of their structural properties. (2) Horizontal dispersion of MWCNTs with and without surfactants, and the integration of MWCNTs to microelectrodes using deposition by dielectrophoresis (DEP) (Chapter 4). We have systematically studied the use of surfactant molecules to disperse and horizontally align MWCNTs on substrates. In addition, DEP is shown to produce impurityfree placement of MWCNTs, forming connections between microelectrodes. We demonstrate the deposition density is tunable by

  6. Enhanced Growth and Redox Characteristics of Some Conducting Polymers on Carbon Nanotube Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    R.Saraswathi

    2007-01-01

    1 Results Recent studies on the electrochemistry of a number of active compounds at carbon nanotube electrodes have proved beyond doubt their excellent electrocatalytic properties.Particularly,the advancements accomplished towards the functionalization of carbon nanotubes resulting in their enhanced solubilization in aqueous solutions have helped in the preparation of stable carbon nanotube electrodes.Glassy carbon has been invariably the preferred substrate for casting carbon nanotube electrodes.Such c...

  7. Carbon nanotube composite materials

    Energy Technology Data Exchange (ETDEWEB)

    O' Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  8. Influence of Ni Catalyst Layer and TiN Diffusion Barrier on Carbon Nanotube Growth Rate

    Directory of Open Access Journals (Sweden)

    Mérel Philippe

    2010-01-01

    Full Text Available Abstract Dense, vertically aligned multiwall carbon nanotubes were synthesized on TiN electrode layers for infrared sensing applications. Microwave plasma-enhanced chemical vapor deposition and Ni catalyst were used for the nanotubes synthesis. The resultant nanotubes were characterized by SEM, AFM, and TEM. Since the length of the nanotubes influences sensor characteristics, we study in details the effects of changing Ni and TiN thickness on the physical properties of the nanotubes. In this paper, we report the observation of a threshold Ni thickness of about 4 nm, when the average CNT growth rate switches from an increasing to a decreasing function of increasing Ni thickness, for a process temperature of 700°C. This behavior is likely related to a transition in the growth mode from a predominantly “base growth” to that of a “tip growth.” For Ni layer greater than 9 nm the growth rate, as well as the CNT diameter, variations become insignificant. We have also observed that a TiN barrier layer appears to favor the growth of thinner CNTs compared to a SiO2 layer.

  9. Growth of nanotubes for electronics

    Directory of Open Access Journals (Sweden)

    John Robertson

    2007-01-01

    Full Text Available The roadmap for semiconductor devices envisages that carbon nanotubes or semiconducting nanowires could become important in about ten years. This article reviews where carbon nanotubes could contribute to microelectronics, in terms of vias, interconnects, and field-effect transistors. It focuses particularly on the requirements microelectronics places on the growth of nanotubes. That is, control over the formation of semiconducting or metallic tubes, controlling the growth location and direction, and achieving high enough nucleation densities.

  10. From Carbon Nanotube Crystals to Carbon Nanotube Flowers

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhengjun; ZHAO Ye; ZHOU Ya

    2005-01-01

    We have investigated the very initial deposition stages of chemical vapor deposition (CVD) with ferrocene (Fe(C5H5)2) and xylene (C8H10) for growing carbon nanotubes, and made clear that the mechanism for the self-organization behaviors of nanotubes at different growth stages by this approach. For instance, the organization of nanotubes into flower-like structures at prolonged deposition is developed from the crystal-like structures formed at early growth stages, both of which are closely related to and determined by the very initial deposition stages of this CVD approach. Based on this approach, ways have been established to build up different architectures of carbon nanotubes, by controlling the initial deposition stages of the CVD process, with which we have realized the selective growth of self-organized carbon nanotube structures. This study provides a new idea for growing carbon nanotube architectures by CVD.

  11. Visualizing the growth dynamics of individual single-wall carbon nanotubes

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Zhang, Lili; He, Maoshuai;

    In order to meet the increasing demand of faster and more flexible electronics and optical devices and at the same time decrease the use of the critical metals, carbon based devices are in fast development. Single walled carbon nanotube (SWCNT) based electronics is a way of addressing...... around the studied sample at elevated temperature gives a unique way of monitoring gas-solid interactions such as CNT growth. Here we show the direct experimental evidence on the growth dynamics of SW-CNTs from Co/MgO catalysts using CO as carbon source inside the environmental TEM. The evolution...

  12. Analysis of Effluent Gases During the CCVD Growth of Multi Wall Carbon Nanotubes from Acetylene

    Science.gov (United States)

    Schmitt, T. C.; Biris, A. S.; Miller, D. W.; Biris, A. R.; Lupu, D.; Trigwell, S.; Rahman, Z. U.

    2005-01-01

    Catalytic chemical vapor deposition was used to grow multi-walled carbon nanotubes on a Fe:Co:CaCO3 catalyst from acetylene. The influent and effluent gases were analyzed by gas chromatography and mass spectrometry at different time intervals during the nanotubes growth process in order to better understand and optimize the overall reaction. A large number of byproducts were identified and it was found that the number and the level for some of the carbon byproducts significantly increased over time. The CaCO3 catalytic support thermally decomposed into CaO and CO2 resulting in a mixture of two catalysts for growing the nanotubes, which were found to have outer diameters belonging to two main groups 8 to 35 nm and 40 to 60 nm, respectively.

  13. Patterned growth of single-walled carbon nanotube arrays from a vapor-deposited Fe catalyst

    OpenAIRE

    Peng, H B; Ristroph, T. G.; Schurmann, G. M.; King, G. M.; Yoon, J; Narayanamurti, Venkatesh; Golovchenko, Jene Andrew

    2003-01-01

    Single-walled carbon nanotubes have been grown on a variety of substrates by chemical vapor deposition using low-coverage vacuum-deposited iron as a catalyst. Ordered arrays of suspended nanotubes ranging from submicron to several micron lengths have been obtained on Si, SiO2,SiO2, Al2O3,Al2O3, and Si3N4Si3N4 substrates that were patterned on hundred nanometer length scales with a focused ion beam machine. Electric fields applied during nanotubegrowth allow the control of growth direction. Na...

  14. Influence of Temperature and Species in the Feedstock on the Growth of Single-Wall Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    赵明文; 马玉臣; 王瑞金; 张华栋; 夏曰源; 李素艳; 梅良模

    2001-01-01

    A molecular dynamics simulation method is used to study the growth of narrow single-wall carbon nanotubes. It is found that the growth temperature and the species of small carbon clusters in the feedstock are important for the quality of the nanotubes grown. There is a temperature range of 1000-1500 K in which the narrow armchair single-wall carbon nanotubes can grow rapidly via adduction of C2 dimers, even without the existence of catalysts. The narrow zigzag tubes cannot keep open-ended growth. If the feedstock consists of various species of carbon clusters, the tubes cannot keep open-ended growth. At higher temperatures, the narrow nanotubes close rapidly in the noncatalytic environment, and the products grown are fullerene-like capsules.

  15. Cyclohexane triggers staged growth of pure and vertically aligned single wall carbon nanotubes

    Science.gov (United States)

    Ayala, P.; Grüneis, A.; Grimm, D.; Kramberger, C.; Engelhard, R.; Rümmeli, M.; Schumann, J.; Kaltofen, R.; Büchner, B.; Schaman, C.; Kuzmany, H.; Gemming, T.; Barreiro, A.; Pichler, T.

    2008-03-01

    An innovative staged chemical vapor deposition (SCVD) approach providing flexible control over the feedstock type during single wall carbon nanotube (SWNTs) growth is proposed. The efficiency of staged growth by means of a cyclohexane/methane system using thin film catalysts is here illustrated. The mechanism involves the nucleation stage efficiently triggered by cyclohexane, followed by methane assisting a growth stage yielding high purity SWNTs vertically aligned with lengths of several hundred μm. In addition, SCVD also facilitates catalyst free SWNT detachment enabling repeated growth.

  16. Effect of catalyst preparation on the yield of carbon nanotube growth

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, Mariano, E-mail: mescobar@df.uba.a [Dep. Quimica Inorganica, Analitica y Quimica Fisica, FCEyN, UBA, Ciudad Universitaria (1428), Bs As (Argentina); LP and MC, Dep. Fisica, FCEyN, UBA (Argentina); Rubiolo, Gerardo [Unidad de Actividad Materiales, CNEA, Av Gral Paz 1499, San Martin (1650), Bs As (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Candal, Roberto [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Instituto de Fisico-quimica de Materiales, Ambiente y Energia (INQUIMAE), CONICET - UBA (Argentina); Goyanes, Silvia [LP and MC, Dep. Fisica, FCEyN, UBA (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)

    2009-10-01

    Multi-wall carbon nanotubes (MWCNTs) were synthesized by catalytic chemical vapor deposition (CVD) on catalytic iron nanoparticles dispersed in a silica matrix, prepared by sol gel method. In this contribution, variation of gelation condition on catalyst structure and its influence on the yield of carbon nanotubes growth was studied. The precursor utilized were tetraethyl-orthosilicate and iron nitrate. The sols were dried at two different temperatures in air (25 or 80 deg. C) and then treated at 450 deg. C for 10 h. The xerogels were introduced into the chamber and reduced in a hydrogen/nitrogen (10%v/v) atmosphere at 600 deg. C. MWCNTs were formed by deposition of carbon atoms from decomposition of acetylene at 700 deg. C. The system gelled at RT shows a yield of 100% respect to initial catalyst mass whereas the yield of that gelled at 80 deg. C was lower than 10%. Different crystalline phases are observed for both catalysts in each step of the process. Moreover, TPR analysis shows that iron oxide can be efficiently reduced to metallic iron only in the system gelled at room temperature. Carbon nanotubes display a diameter of about 25-40 nm and several micron lengths. The growth mechanism of MWCNTs is base growth mode for both catalysts.

  17. Role of the catalyst in the growth of single-wall carbon nanotubes.

    Science.gov (United States)

    Balbuena, Perla B; Zhao, Jin; Huang, Shiping; Wang, Yixuan; Sakulchaicharoen, Nataphan; Resasco, Daniel E

    2006-05-01

    Classical molecular dynamics simulations are carried out to analyze the physical state of the catalyst, and the growth of single-wall carbon nanotubes under typical temperature and pressure conditions of their experimental synthesis, emphasizing the role of the catalyst/substrate interactions. It is found that a strong cluster/substrate interaction increases the cluster melting point, modifying the initial stages of carbon dissolution and precipitation on the cluster surface. Experiments performed on model Co-Mo catalysts clearly illustrate the existence of an initial period where the catalyst is formed and no nanotube growth is observed. To quantify the nature of the Co-Mo2C interaction, quantum density functional theory is applied to characterize structural and energetic features of small Co clusters deposited on a (001) Mo2C surface, revealing a strong attachment of Co-clusters to the Mo2C surface, which may increase the melting point of the cluster and prevent cluster sintering.

  18. The Kinetics of Chirality Assignment in Catalytic Single Walled Carbon Nanotube Growth

    OpenAIRE

    Xu, Ziwei; Yan, Tianying; Ding, Feng

    2014-01-01

    Chirality-selected single-walled carbon nanotubes (SWCNTs) ensure a great potential of building ~1 nm sized electronics. However, the reliable method for chirality-selected SWCNT is still pending. Here we present a theoretical study on the SWCNT's chirality assignment and control during the catalytic growth. This study reveals that the chirality of a SWCNT is determined by the kinetic incorporation of the pentagon formation during SWCNT nucleation. Therefore, chirality is randomly assigned on...

  19. Influence of tungsten on the carbon nanotubes growth by CVD process

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, Mariano [Instituto de Fisicoquimica de Materiales, Ambiente y Energia, CONICET-UBA, Pabellon II, Ciudad Universitaria (1428) Bs As (Argentina); LP and MC, Dep. De Fisica, FCEyN-UBA, Pabellon 1, Ciudad Universitaria (1428) Bs As (Argentina)], E-mail: mescobar@qi.fcen.uba.ar; Rubiolo, Gerardo H. [LP and MC, Dep. De Fisica, FCEyN-UBA, Pabellon 1, Ciudad Universitaria (1428) Bs As (Argentina); Unidad de Actividad Materiales, CNEA, Av. Gral. Paz 1499, San Martin (1650), Bs As (Argentina); Moreno, M. Sergio [Centro Atomico Bariloche, (8400) S.C. de Bariloche, Rio Negro (Argentina); Goyanes, Silvia [LP and MC, Dep. De Fisica, FCEyN-UBA, Pabellon 1, Ciudad Universitaria (1428) Bs As (Argentina); Candal, Roberto [Instituto de Fisicoquimica de Materiales, Ambiente y Energia, CONICET-UBA, Pabellon II, Ciudad Universitaria (1428) Bs As (Argentina)

    2009-06-24

    The effect of tungsten (W) on the growth of multi-walled carbon nanotubes (MWNTs) using the chemical vapour deposition (CVD) process over a metal Fe-W catalyst incorporated into a silica matrix is reported. A W molar content in Fe/SiO{sub 2} up to 10% was studied. The incorporation of only 2% of W substantially modifies the crystalline phases and the crystalline degree of the catalyst during the MWNTs synthesis. This fact seems to have a strong influence on the type and yield of the carbonaceous species obtained by the CVD of acetylene, at 600 deg. C and 180 Torr, over each catalyst. Tungsten interacts with iron within the matrix, diminishing the catalytic activity of the metal nanoparticles, and both, carbon nanotubes and carbon nanofibers, are obtained when tungsten is present. The results obtained support the hypothesis of a base growth model for carbon nanotubes indicating a strong interaction between silica matrix and Fe/W nanoparticles, independently of the content of W.

  20. Effects of Temperature and Catalyst Concentration on the Growth of Aligned Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    BAI Xiaodong; LI Dan; WANG Ye; LIANG Ji

    2005-01-01

    The effects of preheating and pyrolysis temperatures and catalyst concentration on the synthesis of aligned carbon nanotubes (CNTs) using ferrocene as the catalyst and xylene as the carbon source in chemical vapor deposition were experimentally studied. The as-grown aligned CNTs were characterized by field emission scanning electron microscopy, transmission electronic microscopy, high-resolution transmission electronic microscopy, and Raman spectroscopy. The growth rate, the diameters, and the degree of crystal structure of the aligned CNTs were all found to depend on the preheating and pyrolysis temperatures and the catalyst concentration. The optimized conditions for the growth of aligned CNTs resulted in a rapid growth rate of 20.4 μm/min, with the CNTs having a good, uniform crystal structure, and clean surfaces with little amorphous carbon. The results also show that higher preheating temperatures and lower ferrocene concentrations favor the growth of single-walled CNTs.

  1. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  2. Carbon nanotube quantum dots

    NARCIS (Netherlands)

    Sapmaz, S.

    2006-01-01

    Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small si

  3. Synthesis of carbon nanotubes.

    Science.gov (United States)

    Awasthi, Kalpana; Srivastava, Anchal; Srivastava, O N

    2005-10-01

    Carbon nanotubes play a fundamental role in the rapidly developing field of nanoscience and nanotechnology because of their unique properties and high potential for applications. In this article, the different synthesis methods of carbon nanotubes (both multi-walled and single-walled) are reviewed. From the industrial point of view, the chemical vapor deposition method has shown advantages over laser vaporization and electric arc discharge methods. This article also presents recent work in the controlled synthesis of carbon nanotubes with ordered architectures. Special carbon nanotube configurations, such as nanocoils, nanohorns, bamboo-shaped and carbon cylinder made up from carbon nanotubes are also discussed.

  4. Growth Mechanism of Single-Walled Carbon Nanotubes on Iron–Copper Catalyst and Chirality Studies by Electron Diffraction

    DEFF Research Database (Denmark)

    He, Maoshuai; Liu, Bilu; Chernov, Alexander I.

    2012-01-01

    Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type...... by impregnation, showing similar catalytic performance as the atomic layer deposition-prepared catalyst, yielding single-walled carbon nanotubes with a similar narrow chirality distribution....

  5. Chemical vapor deposition of carbon nanotubes: a review on growth mechanism and mass production.

    Science.gov (United States)

    Kumar, Mukul; Ando, Yoshinori

    2010-06-01

    This review article deals with the growth mechanism and mass production of carbon nanotubes (CNTs) by chemical vapor deposition (CVD). Different aspects of CNT synthesis and growth mechanism are reviewed in the light of latest progresses and understandings in the field. Materials aspects such as the roles of hydrocarbon, catalyst and catalyst support are discussed. Many new catalysts and new carbon sources are described. Growth-control aspects such as the effects of temperature, vapor pressure and catalyst concentration on CNT diameter distribution and single- or multi-wall formation are explained. Latest reports of metal-catalyst-free CNT growth are considered. The mass-production aspect is discussed from the perspective of a sustainable CNT technology. Existing problems and challenges of the process are addressed with future directions.

  6. Carbon Nanotubes for Space Applications

    Science.gov (United States)

    Meyyappan, Meyya

    2000-01-01

    The potential of nanotube technology for NASA missions is significant and is properly recognized by NASA management. Ames has done much pioneering research in the last five years on carbon nanotube growth, characterization, atomic force microscopy, sensor development and computational nanotechnology. NASA Johnson Space Center has focused on laser ablation production of nanotubes and composites development. These in-house efforts, along with strategic collaboration with academia and industry, are geared towards meeting the agency's mission requirements. This viewgraph presentation (including an explanation for each slide) outlines the research focus for Ames nanotechnology, including details on carbon nanotubes' properties, applications, and synthesis.

  7. Initial stage of growth of single-walled carbon nanotubes: modeling and simulations.

    Science.gov (United States)

    Chaudhuri, I; Yu, Ming; Jayanthi, C S; Wu, S Y

    2014-03-19

    Because there are different pathways to grow carbon nanotubes (CNTs), a common mechanism for the synthesis of CNTs does not likely exist. However, after carbon atoms are liberated from carbon-containing precursors by catalysts or from pure carbon systems, a common feature, the nucleation of CNTs by electron mediation, does appear. We studied this feature using the initial stage of growth of single wall CNTs (SWCNTs) by transition metal nano-particle catalysts as the working example. To circumvent the bottleneck due to the size and simulation time, we used a model in which the metal droplet is represented by a jellium, and the effect of collisions between the carbon atoms and atoms of the catalyst is captured by charge transfers between the jellium and the carbon. The simulations were performed using a transferable semi-empirical Hamiltonian to model the interactions between carbon atoms in jellium. We annealed different initial configurations of carbon clusters in jellium as well as in a vacuum. We found that in jellium, elongated open tubular structures, precursors to the growth of SWCNTs, are formed. Our model was also shown to be capable of mimicking the continued growth when more atoms were placed near the open end of the tubular structure.

  8. Carbon Nanotubes and Modern Nanoagriculture

    KAUST Repository

    Bayoumi, Maged Fouad

    2015-01-27

    Since their discovery, carbon nanotubes have been prominent members of the nanomaterial family. Owing to their extraordinary physical, chemical, and mechanical properties, carbon nanotubes have been proven to be a useful tool in the field of plant science. They were frequently perceived to bring about valuable biotechnological and agricultural applications that still remain beyond experimental realization. An increasing number of studies have demonstrated the ability of carbon nanotubes to traverse different plant cell barriers. These studies, also, assessed the toxicity and environmental impacts of these nanomaterials. The knowledge provided by these studies is of practical and fundamental importance for diverse applications including intracellular labeling and imaging, genetic transformation, and for enhancing our knowledge of plant cell biology. Although different types of nanoparticles have been found to activate physiological processes in plants, carbon nanotubes received particular interest. Following addition to germination medium, carbon nanotubes enhanced root growth and elongation of some plants such as onion, cucumber and rye-grass. They, also, modulated the expression of some genes that are essential for cell division and plant development. In addition, multi-walled carbon nanotubes were evidenced to penetrate thick seed coats, stimulate germination, and to enhance growth of young tomato seedlings. Multi-walled carbon nanotubes can penetrate deeply into the root system and further distribute into the leaves and the fruits. In recent studies, carbon nanotubes were reported to be chemically entrapped into the structure of plant tracheary elements. This should activate studies in the fields of plant defense and wood engineering. Although, all of these effects on plant physiology and plant developmental biology have not been fully understood, the valuable findings promises more research activity in the near future toward complete scientific understanding of

  9. Carbon nanotubes as plant growth regulators: effects on tomato growth, reproductive system, and soil microbial community.

    Science.gov (United States)

    Khodakovskaya, Mariya V; Kim, Bong-Soo; Kim, Jong Nam; Alimohammadi, Mohammad; Dervishi, Enkeleda; Mustafa, Thikra; Cernigla, Carl E

    2013-01-14

    Multi-walled carbon nanotubes (CNTs) can affect plant phenotype and the composition of soil microbiota. Tomato plants grown in soil supplemented with CNTs produce two times more flowers and fruit compared to plants grown in control soil. The effect of carbon nanotubes on microbial community of CNT-treated soil is determined by denaturing gradient gel electrophoresis and pyrosequencing analysis. Phylogenetic analysis indicates that Proteobacteria and Bacteroidetes are the most dominant groups in the microbial community of soil. The relative abundances of Bacteroidetes and Firmicutes are found to increase, whereas Proteobacteria and Verrucomicorbia decrease with increasing concentration of CNTs. The results of comparing diversity indices and species level phylotypes (OTUs) between samples showed that there is not a significant affect on bacterial diversity.

  10. GROWTH OF CARBON NANOTUBES ON CARBON FIBRES AND THE TENSILE PROPERTIES OF RESULTING CARBON FIBRE REINFORCED POLYPROPYLENE COMPOSITES

    Directory of Open Access Journals (Sweden)

    A.R. SURAYA

    2009-12-01

    Full Text Available Carbon nanotubes were grown directly on carbon fibres using the chemical vapor deposition technique. The effects of reaction temperature (800-900oC and hydrogen gas flowrate (100-300 ml/min on the morphology of the carbon nanotube coating were investigated. Carbon nanotubes produced were characterized using scanning electron microscope and transmission electron microscope. The resulting fibres were compounded with polypropylene to produce carbon fibre reinforced polypropylene composites. The tensile properties of these composites were determined to investigate the effects of the carbon nanotubes on the overall performance of the composites. The optimum treatment condition that produced the thickest coating of carbon nanotubes was obtained at 800oC and 300 ml/min hydrogen gas flowrate. The composite sample obtained under these conditions demonstrated remarkable enhancement in tensile properties compared to composites made from as-received carbon fibres, whereby an increment of up to 52% and 133% was observed for the tensile strength and modulus respectively.

  11. Comparison study of catalyst nanoparticle formation and carbon nanotube growth: Support effect

    Science.gov (United States)

    Wang, Yunyu; Luo, Zhiquan; Li, Bin; Ho, Paul S.; Yao, Zhen; Shi, Li; Bryan, Eugene N.; Nemanich, Robert J.

    2007-06-01

    A comparison study has been conducted on the formation of catalyst nanoparticles on a high surface tension metal and low surface tension oxide for carbon nanotube (CNT) growth via catalytic chemical vapor deposition (CCVD). Silicon dioxide (SiO2) and tantalum have been deposited as supporting layers before deposition of a thin layer of iron catalyst. Iron nanoparticles were formed after thermal annealing. It was found that densities, size distributions, and morphologies of iron nanoparticles were distinctly different on the two supporting layers. In particular, iron nanoparticles revealed a Volmer-Weber growth mode on SiO2 and a Stranski-Krastanov mode on tantalum. CCVD growth of CNTs was conducted on iron/tantalum and iron/SiO2. CNT growth on SiO2 exhibited a tip growth mode with a slow growth rate of less than 100nm /min. In contrast, the growth on tantalum followed a base growth mode with a fast growth rate exceeding 1μm/min. For comparison, plasma enhanced CVD was also employed for CNT growth on SiO2 and showed a base growth mode with a growth rate greater than 2μm /min. The enhanced CNT growth rate on tantalum was attributed to the morphologies of iron nanoparticles in combination with the presence of an iron wetting layer. The CNT growth mode was affected by the adhesion between the catalyst and support as well as CVD process.

  12. In-situ localized carbon nanotube growth inside partially sealed enclosures

    NARCIS (Netherlands)

    Burgt, Y. van de; Champion, A.; Bellouard, Y.

    2013-01-01

    Carbon nanotube assemblies can be used for specific applications such as sensors and filters. We present a method and proof-of-concept to directly grow vertically-aligned carbon nanotube structures within sealed enclosures by means of a feedback-controlled laser-assisted chemical vapor deposition te

  13. Understanding the growth mechanism of carbon nanotubes via the ``cluster volume to surface area" model

    Science.gov (United States)

    Mandati, Sreekanth; Kunstmann, Jens; Boerrnert, Felix; Schoenfelder, Ronny; Ruemmeli, Mark; Kar, Kamal K.; Cuniberti, Gianaurelio

    2010-03-01

    The influence of mixed catalysts for the high yield production of carbon nanotubes (CNTs) has been studied systematically. Based on extensive experimental data a ``Catalyst Volume to Surface Area'' (CVSA) model was developed to understand the influence of the process parameters on the yield and CNT diameter distribution [1]. In our study, we present a refined version of the CVSA model developed by combining experiments and simulations. We discuss our current understanding of the growth mechanism and how the model might be used to increase CNT yields by using mixed catalysts.[4pt] [1] S. Tetali et al., ACS Nano (2009), DOI: 10.1021/nn9012548.

  14. Effect of Particle Density on the Aligned Growth of Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Sheng-gao; WANG Jian-hua; HAN Jian-jun

    2004-01-01

    Aligned carbon nanotubes (CNTs) were prepared on Ni-coated Ni substrate by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at temperature of 550℃.The experimental results show a direct correlation between the alignment of CNTs and the density of the catalyst particles at low temperature.When the particle density is high enough,among CNTs there are strong interactions that can inhibit CNTs from growing randomly.The crowding effect among dense CNTs results in the aligned growth of CNTs at low temperature.

  15. Molecular dynamics study of the catalyst particle size dependence on carbon nanotube growth

    Science.gov (United States)

    Ding, Feng; Rosén, Arne; Bolton, Kim

    2004-08-01

    The molecular dynamics method, based on an empirical potential energy surface, was used to study the effect of catalyst particle size on the growth mechanism and structure of single-walled carbon nanotubes (SWNTs). The temperature for nanotube nucleation (800-1100 K), which occurs on the surface of the cluster, is similar to that used in catalyst chemical vapor deposition experiments, and the growth mechanism, which is described within the vapor-liquid-solid model, is the same for all cluster sizes studied here (iron clusters containing between 10 and 200 atoms were simulated). Large catalyst particles, which contain at least 20 iron atoms, nucleate SWNTs that have a far better tubular structure than SWNTs nucleated from smaller clusters. In addition, the SWNTs that grow from the larger clusters have diameters that are similar to the cluster diameter, whereas the smaller clusters, which have diameters less than 0.5 nm, nucleate nanotubes that are ≈0.6-0.7 nm in diameter. This is in agreement with the experimental observations that SWNT diameters are similar to the catalyst particle diameter, and that the narrowest free-standing SWNT is 0.6-0.7 nm.

  16. PECVD-grown carbon nanotubes on silicon substrates with a nickel-seeded tip-growth structure

    Energy Technology Data Exchange (ETDEWEB)

    Abdi, Y. [Thin Film Laboratory, ECE Department, University of Tehran, Tehran (Iran, Islamic Republic of); Physics Department, University of Tehran, Tehran (Iran, Islamic Republic of); Koohsorkhi, J. [Thin Film Laboratory, ECE Department, University of Tehran, Tehran (Iran, Islamic Republic of); Physics Department, University of Tehran, Tehran (Iran, Islamic Republic of); Derakhshandeh, J. [Thin Film Laboratory, ECE Department, University of Tehran, Tehran (Iran, Islamic Republic of)]. E-mail: derakhshad@yahoo.com; Mohajerzadeh, S. [Thin Film Laboratory, ECE Department, University of Tehran, Tehran (Iran, Islamic Republic of)]. E-mail: smohajer@tfl.ir; Hoseinzadegan, H. [Thin Film Laboratory, ECE Department, University of Tehran, Tehran (Iran, Islamic Republic of); Robertson, M.D. [Department of Physics, Acadia University, Wolfville, Nova Scotia (Canada); Bennett, J.C. [Department of Physics, Acadia University, Wolfville, Nova Scotia (Canada); Wu, X. [Institute for Microstructural Sciences, National Research Council, Ottawa, Ontario (Canada); Radamson, H. [Thin Film Laboratory, ECE Department, University of Tehran, Tehran (Iran, Islamic Republic of)

    2006-07-15

    Vertically aligned carbon nanotubes were grown on silicon substrates by DC-PECVD using nickel as the catalyst particle and a mixture of acetylene and hydrogen as the feed gases. It was observed that larger nickel particles resulted in larger diameter nanotubes whereas lower plasma power densities increased the spatial density of the nanotubes. The carbon nanotubes were characterized by scanning and transmission-electron microscopies and the growth mode was found to be tip initiated. The external diameter of the tubes ranged between 50 nm and 100 nm depending on the growth conditions and the diameter of the internal pore of the tube varied between about 5 nm and 8 nm. Selected area electron diffraction patterns taken from the nickel catalyst particle located at the tip of the tube suggest that (011) lattice planes may be the catalytically active sites on the top surface of the nickel.

  17. Chitin and carbon nanotube composites as biocompatible scaffolds for neuron growth

    Science.gov (United States)

    Singh, Nandita; Chen, Jinhu; Koziol, Krzysztof K.; Hallam, Keith R.; Janas, Dawid; Patil, Avinash J.; Strachan, Ally; G. Hanley, Jonathan; Rahatekar, Sameer S.

    2016-04-01

    The design of biocompatible implants for neuron repair/regeneration ideally requires high cell adhesion as well as good electrical conductivity. Here, we have shown that plasma-treated chitin carbon nanotube composite scaffolds show very good neuron adhesion as well as support of synaptic function of neurons. The addition of carbon nanotubes to a chitin biopolymer improved the electrical conductivity and the assisted oxygen plasma treatment introduced more oxygen species onto the chitin nanotube scaffold surface. Neuron viability experiments showed excellent neuron attachment onto plasma-treated chitin nanotube composite scaffolds. The support of synaptic function was evident on chitin/nanotube composites, as confirmed by PSD-95 staining. The biocompatible and electrically-conducting chitin nanotube composite scaffold prepared in this study can be used for in vitro tissue engineering of neurons and, potentially, as an implantable electrode for stimulation and repair of neurons.

  18. Theoretical study on the 4-angstrom carbon nanotube growth mechanisms inside microporous aluminum phosphate-5

    Science.gov (United States)

    Liu, Jianwen

    The growth mechanisms of mono-sized and parallel-aligned single wall carbon nanotube (CNT) in the microporous channels of AlPO4-5 are investigated by density functional theory calculations. Detailed mechanisms are proposed for the decomposition of TPA, the formation of aromatic ring, and the growth of carbon nanotubes. In the first part, the mechanisms for the dissociation of TPA are studied under three types of conditions. The unimolecular dissociation is initiated by the breaking of either the N-Calpha and Calpha -Cbeta bonds and leads to many complicated processes. Within the confined space inside neutral zeolite channels, the diffusion of H radicals enhances a cycle of reactions, which accounts for the experimental observation of dipropylamine and monopropylamine. In the presence of an acidic site, the dissociation of TPA goes through catalyzed successive steps to produce ammonia and propylene molecules. In the second part, A T5 cluster model is used to investigate mechanisms of propylene aromatization to benzene, which involves chemisorption, dimerization, cyclization and dehydrogenation. Propylene can be chemisorbed to form two distinct products, n-propoxide and i-propoxide, which can further be dimerizated to form longer chain olefins 1-hexene and 2-hexene (from n-propoxide), and 4-methyl-1-pentene and 4-methyl-2-penetene (from i-propoxide). Initiated by H2 elimination, these dimerization products can further go through cyclization process to generated either 6-member ring cyclohexene or 5-member ring methyl-cyclopentene. Catalyzed by zeolite, cyclohexene can directly dehydrogenate to form benzene whereas methyl-cyclopentene can dehydrogenate to form fulven, an isomer to benzene. Under acidic zeolite environment, a fulvene can readily be transformed to the thermodynamically more stable benzene. In the last part, two distinct paths are proposed to investigate the carbon nanotube growth mechanism using benzene as the growth seed and propylene as carbon

  19. Selective growth of palladium and titanium dioxide nanostructures inside carbon nanotube membranes

    Science.gov (United States)

    Hevia, Samuel; Homm, Pía; Cortes, Andrea; Núñez, Verónica; Contreras, Claudia; Vera, Jenniffer; Segura, Rodrigo

    2012-06-01

    Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors.

  20. Mechanism of the initial stages of nitrogen-doped single-walled carbon nanotube growth.

    Science.gov (United States)

    Susi, Toma; Lanzani, Giorgio; Nasibulin, Albert G; Ayala, Paola; Jiang, Tao; Bligaard, Thomas; Laasonen, Kari; Kauppinen, Esko I

    2011-06-21

    We have studied the mechanism of the initial stages of nitrogen-doped single-walled carbon nanotube growth illustrated for the case of a floating catalyst chemical vapor deposition system, which uses carbon monoxide (CO) and ammonia (NH(3)) as precursors and iron as a catalyst. We performed first-principles electronic-structure calculations, fully incorporating the effects of spin polarization and magnetic moments, to investigate the bonding and chemistry of CO, NH(3), and their fragments on a model Fe(55) icosahedral cluster. A possible dissociation path for NH(3) to atomic nitrogen and hydrogen was identified, with a reaction barrier consistent with an experimentally determined value we measured by tandem infrared and mass spectrometry. Both C-C and C-N bond formation reactions were found to be barrierless and exothermic, while a parasitic reaction of HCN formation had a barrier of over 1 eV.

  1. Thermal conductivity of vertically aligned carbon nanotube arrays: Growth conditions and tube inhomogeneity

    Science.gov (United States)

    Bauer, Matthew L.; Pham, Quang N.; Saltonstall, Christopher B.; Norris, Pamela M.

    2014-10-01

    The thermal conductivity of vertically aligned carbon nanotube arrays (VACNTAs) grown on silicon dioxide substrates via chemical vapor deposition is measured using a 3ω technique. For each sample, the VACNTA layer and substrate are pressed to a heating line at varying pressures to extract the sample's thermophysical properties. The nanotubes' structure is observed via transmission electron microscopy and Raman spectroscopy. The presence of hydrogen and water vapor in the fabrication process is tuned to observe the effect on measured thermal properties. The presence of iron catalyst particles within the individual nanotubes prevents the array from achieving the overall thermal conductivity anticipated based on reported measurements of individual nanotubes and the packing density.

  2. Dysprosium-Catalyzed Growth of Single-Walled Carbon Nanotube Arrays on Substrates

    Directory of Open Access Journals (Sweden)

    Qian Yong

    2009-01-01

    Full Text Available Abstract In this letter, we report that dysprosium is an effective catalyst for single-walled carbon nanotubes (SWNTs growth via a chemical vapor deposition (CVD process for the first time. Horizontally superlong well-oriented SWNT arrays on SiO2/Si wafer can be fabricated by EtOH-CVD under suitable conditions. The structure and properties are characterized by scanning electron microscopy, transition electron microscopy, Raman spectroscopy and atomic force microscopy. The results show that the SWNTs from dysprosium have better structural uniformity and better conductivity with fewer defects. This rare earth metal provides not only an alternative catalyst for SWNTs growth, but also a possible method to generate high percentage of superlong semiconducting SWNT arrays for various applications of nanoelectronic device.

  3. Growth of Aligned Multiwall Carbon Nanotubes and the Effect of Adsorbates on the Field Emission Properties

    Science.gov (United States)

    Milne, W. I.; Teo, K. B. K.; Lansley, S. B.; Chhowalla, M.; Amaratunga, G. A. J.; Semet, V.; Binh, Vu Thien; Pirio, G.; Legagneux, P.

    2003-10-01

    In attempt to decipher the field emission characteristics of multiwall carbon nanotubes (MWCNTs), we have developed a fabrication method based on plasma enhanced chemical vapour deposition (PECVD) to provide utmost control of the nanotube structure such as their alignment, individual position, diameter, length and morphology. We investigated the field emission properties of these nanotubes to elucidate the effect of adsorbates on the nanotubes. Our results show that although the adsorbates cause an apparent lowering of the required turn on voltage/field of the nanotubes, the adsorbates undesirably cause a saturation of the current, large temporal fluctuations in the current, and also a deviation of the emission characteristics from Fowler-Nordheim like emission. The adsorbates are easily removed by extracting an emission current of 1 uA per nanotube or using a high applied electric field (˜25V/um).

  4. Carbon nanotubes-porous ceramic composite by in situ CCVD growth of CNTs

    Energy Technology Data Exchange (ETDEWEB)

    Mazumder, Sangram; Sarkar, Naboneeta; Park, Jung Gyu [Institute of Processing and Application of Inorganic Materials (PAIM), Department of Materials Science and Engineering, Hanseo University, #360 Daegok-ri, Haemi-myeon, Seosan-si, Chungnam, 356-706 (Korea, Republic of); Han, In Sub [Korea Institute of Energy Research (KIER), #152 Gajeong-gu, Daejeon 305-343 (Korea, Republic of); Kim, Ik Jin, E-mail: ijkim@hanseo.ac.kr [Institute of Processing and Application of Inorganic Materials (PAIM), Department of Materials Science and Engineering, Hanseo University, #360 Daegok-ri, Haemi-myeon, Seosan-si, Chungnam, 356-706 (Korea, Republic of)

    2016-03-01

    A novel approach towards the formation of Carbon nanotubes-porous alumina ceramic composite was attempted by the application of three different reaction techniques. Porous alumina ceramics having micrometer pore dimensions were developed using the direct foaming technique. NaA zeolites were simultaneously synthesized and coated within the porous ceramics by an in situ hydrothermal process and were subjected to a simple ion exchange reaction for preparing the suitable catalyst material for Carbon nanotubes (CNTs) synthesis. The catalytic chemical vapour deposition (CCVD) technique was used to grow CNTs within the porous ceramics and the effect of growth time on the synthesized CNTs were investigated. Phase compositions of the samples were analysed by X-ray diffractometer (XRD). Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) were used for morphology, surface quality and structural analysis. Crystallinity, defects and yield were studied by Raman spectroscopy and thermogravimetric analysis (TGA). - Highlights: • Novel processing route of MWCNTs grown on Cobalt-zeolites-porous ceramics by CCVD. • CCVD time of 120 min produced MWCNTs with most prominent tube-like structure. • 120 min produced highest yield (19.46%) of CNTs with an I{sub D}/I{sub G} ratio of 0.88.

  5. Growth of half-meter long carbon nanotubes based on Schulz-Flory distribution.

    Science.gov (United States)

    Zhang, Rufan; Zhang, Yingying; Zhang, Qiang; Xie, Huanhuan; Qian, Weizhong; Wei, Fei

    2013-07-23

    The Schulz-Flory distribution is a mathematical function that describes the relative ratios of polymers of different length after a polymerization process, based on their relative probabilities of occurrence. Carbon nanotubes (CNTs) are big carbon molecules which have a very high length-to-diameter ratio, somewhat similar to polymer molecules. Large amounts of ultralong CNTs have not been obtained although they are highly desired. Here, we report that the Schulz-Flory distribution can be applied to describe the relative ratios of CNTs of different lengths produced with a floating chemical vapor deposition process, based on catalyst activity/deactivation probability. With the optimized processing parameters, we successfully synthesized 550-mm-long CNTs, for which the catalyst deactivation probability of a single growth step was ultralow. Our finding bridges the Schulz-Flory distribution and the synthesis of one-dimensional nanomaterials for the first time, and sheds new light on the rational design of process toward controlled production of nanotubes/nanowires.

  6. DNA-directed growth of Pd nanocrystals on carbon nanotubes towards efficient oxygen reduction reactions.

    Science.gov (United States)

    Zhang, Lian Ying; Guo, Chun Xian; Cui, Zhiming; Guo, Jun; Dong, Zhili; Li, Chang Ming

    2012-12-03

    Unique DNA-promoted Pd nanocrystals on carbon nanotubes (Pd/DNA-CNTs) are synthesized for the first time, in which through its regularly arranged PO(4)(3-) groups on the sugar-phosphate backbone, DNA directs the growth of ultrasmall Pd nanocrytals with an average size of 3.4 nm uniformly distributed on CNTs. The Pd/DNA-CNT catalyst shows much more efficient electrocatalytic activity towards oxygen reduction reaction (ORR) with a much more positive onset potential, higher catalytic current density and better stability than other Pd-based catalysts including Pd nanocrystals on carbon nanotubes (Pd/CNTs) without the use of DNA and commercial Pd/C catalyst. In addition, the Pd/DNA-CNTs catalyst provides high methanol tolerance. The high electrocatalytic performance is mainly contributed by the ultrasmall Pd nanocrystal particles grown directed by DNA to enhance the mass transport rate and to improve the utilization of the Pd catalyst. This work may demonstrate a universal approach to fabricate other superior metal nanocrystal catalysts with DNA promotion for broad applications in energy systems and sensing devices.

  7. Study of Mg Powder as Catalyst Carrier for the Carbon Nanotube Growth by CVD

    Directory of Open Access Journals (Sweden)

    Jianli Kang

    2011-01-01

    Full Text Available The possibility of using magnesium powder as catalyst carrier for carbon nanotube growth by chemical vapor deposition, which may pave a new way to in situ fabricate CNT/Mg composites with high CNT dispersion, was investigated for the first time. The fabrication process of the catalyst supported on Mg powder involves the preparation of colloid by a deposition-precipitation method, followed by calcination and reduction. The results show that the interaction between catalyst and support plays an important role for the catalytic property of the catalyst. Ni alloyed with Mg shows no activity for the decomposition of methane. The introduction of Y in Ni/Mg catalyst can promote the reaction temperature between Ni and Mg and thus enhance the activity of the catalyst. A large amount of carbon nanotubes (CNTs with an average diameter of 20 nm was obtained using Ni/Y/Mg catalyst at 450∘C, while only a few short CNTs were obtained using Ni/Mg catalyst due to the low activity of the catalyst at lower temperature.

  8. Growth dynamics of carbon-metal particles and nanotubes synthesized by CO2 laser vaporization

    Science.gov (United States)

    Kokai, F.; Takahashi, K.; Yudasaka, M.; Iijima, S.

    To study the growth of carbon-Co/Ni particles and single-wall carbon nanotubes (SWNTs) by 20 ms CO2 laser-pulse irradiation of a graphite-Co/Ni (1.2 at.%) target in an Ar gas atmosphere (600 Torr), we used emission imaging spectroscopy and shadowgraphy with a temporal resolution of 1.67 ms. Wavelength-selected emission images showed that C2 emission was strong in the region close to the target (within 2 cm), while for the same region the blackbody radiation from the large clusters or particles increased with increasing distance from the target. Shadowgraph images showed that the viscous flow of carbon and metal species formed a mushroom or a turbulent cloud spreading slowly into the Ar atmosphere, indicating that particles and SWNTs continued to grow as the ejected material cooled. In addition, emission imaging spectroscopy at 1200 °C showed that C2 and hot clusters and particles with higher emission intensities were distributed over much wider areas. We discuss the growth dynamics of the particles and SWNTs through the interaction of the ambient Ar with the carbon and metal species released from the target by the laser pulse.

  9. Controlled Growth and Modification of Vertically-Aligned Carbon Nanotubes for Multifunctional Applications

    Science.gov (United States)

    2010-01-01

    addition of H2O into the nanotube-growth CVD system prevented Fe catalyst particles from aggregation through Ostwald ripening due to retarded...polymerization of acetaldehyde . The insets show TEM images of an individual nanotube (a) before and (b) after being coated with a layer of the acetaldehyde

  10. Chiral-Selective Growth of Single-Walled Carbon Nanotubes on Lattice-Mismatched Epitaxial Cobalt Nanoparticles

    DEFF Research Database (Denmark)

    He, Maoshuai; Jiang, Hua; Liu, Bilu

    2013-01-01

    Controlling chirality in growth of single-walled carbon nanotubes (SWNTs) is important for exploiting their practical applications. For long it has been conceptually conceived that the structural control of SWNTs is potentially achievable by fabricating nanoparticle catalysts with proper structur...

  11. Modeling plasma-assisted growth of graphene-carbon nanotube hybrid

    Science.gov (United States)

    Tewari, Aarti

    2016-08-01

    A theoretical model describing the growth of graphene-CNT hybrid in a plasma medium is presented. Using the model, the growth of carbon nanotube (CNT) on a catalyst particle and thereafter the growth of the graphene on the CNT is studied under the purview of plasma sheath and number density kinetics of different plasma species. It is found that the plasma parameter such as ion density; gas ratios and process parameter such as source power affect the CNT and graphene dimensions. The variation in growth rates of graphene and CNT under different plasma power, gas ratios, and ion densities is analyzed. Based on the results obtained, it can be concluded that higher hydrocarbon ion densities and gas ratios of hydrocarbon to hydrogen favor the growth of taller CNTs and graphene, respectively. In addition, the CNT tip radius reduces with hydrogen ion density and higher plasma power favors graphene with lesser thickness. The present study can help in better understanding of the graphene-CNT hybrid growth in a plasma medium.

  12. Nanomechanics of carbon nanotubes.

    Science.gov (United States)

    Kis, Andras; Zettl, Alex

    2008-05-13

    Some of the most important potential applications of carbon nanotubes are related to their mechanical properties. Stiff sp2 bonds result in a Young's modulus close to that of diamond, while the relatively weak van der Waals interaction between the graphitic shells acts as a form of lubrication. Previous characterization of the mechanical properties of nanotubes includes a rich variety of experiments involving mechanical deformation of nanotubes using scanning probe microscopes. These results have led to promising prototypes of nanoelectromechanical devices such as high-performance nanomotors, switches and oscillators based on carbon nanotubes.

  13. Catalyzed growth of oriented carbon nanotubes using Fe organosilicon core shell nanoparticles

    Science.gov (United States)

    Fleaca, C. T.; Morjan, I.; Alexandrescu, R.; Dumitrache, F.; Soare, I.; Gavrila-Florescu, L.; Le Normand, F.; Ersen, O.

    2008-05-01

    Iron-based nanocomposites were synthesized by the CO 2 laser-induced co-pyrolysis of Fe(CO) 5 and [(CH 3) 3Si] 2O (HMDSO) vapors. The obtained nanoparticles exhibited an iron-based core surrounded by an organosilicon polymer shell. Particles having different thicknesses of the polymer shell were deposited by either a spin-coating or by a drop-casting method on Si(1 0 0) substrates. Carbon nanotubes (CNTs) were grown by dc plasma-assisted and filaments-activated CCVD processes in H 2/C 2H 2 mixtures at 700 °C. The CNT growth was studied by several analytical techniques: SEM, TEM and Raman spectroscopy. High density of well-aligned, vertical MWCNTs was obtained.

  14. Enhanced cold wall CVD reactor growth of horizontally aligned single-walled carbon nanotubes

    Science.gov (United States)

    Mu, Wei; Kwak, Eun-Hye; Chen, Bingan; Huang, Shirong; Edwards, Michael; Fu, Yifeng; Jeppson, Kjell; Teo, Kenneth; Jeong, Goo-Hwan; Liu, Johan

    2016-05-01

    HASynthesis of horizontally-aligned single-walled carbon nanotubes (HA-SWCNTs) by chemical vapor deposition (CVD) directly on quartz seems very promising for the fabrication of future nanoelectronic devices. In comparison to hot-wall CVD, synthesis of HA-SWCNTs in a cold-wall CVD chamber not only means shorter heating, cooling and growth periods, but also prevents contamination of the chamber. However, since most synthesis of HA-SWCNTs is performed in hot-wall reactors, adapting this well-established process to a cold-wall chamber becomes extremely crucial. Here, in order to transfer the CVD growth technology from a hot-wall to a cold-wall chamber, a systematic investigation has been conducted to determine the influence of process parameters on the HA-SWCNT's growth. For two reasons, the cold-wall CVD chamber was upgraded with a top heater to complement the bottom substrate heater; the first reason to maintain a more uniform temperature profile during HA-SWCNTs growth, and the second reason to preheat the precursor gas flow before projecting it onto the catalyst. Our results show that the addition of a top heater had a significant effect on the synthesis. Characterization of the CNTs shows that the average density of HA-SWCNTs is around 1 - 2 tubes/ μm with high growth quality as shown by Raman analysis. [Figure not available: see fulltext.

  15. Local growth of aligned carbon nanotubes at surface sites irradiated by pulsed laser

    Science.gov (United States)

    Zimmer, K.; Böhme, R.; Rauschenbach, B.

    2008-05-01

    The utilization of the unique properties of nanostructures often requires their arrangement in mesoscopic patterns, e.g., to facilitate the connection to microelectrodes. Such arrangements can be achieved by local growth of nanostructures. The stimulation of the localized growth of carbon nanotubes (CNT) has been achieved by excimer laser irradiation of iron(III)nitride-coated silicon substrates at a wavelength of 248 nm. After the growth using a thermal CVD process, vertical aligned CNT bundles were found within the laser-irradiated areas. Pulsed UV-laser irradiation causes the transformation of the nitride film into nanoparticles at the substrate surface as AFM measurements show. Surface modification by direct writing techniques allows the growth of arbitrary shaped CNT-forest patterns. Despite the optimization of the processing parameters, an unequal growth of CNT has been observed at the regions of pulse overlap at direct writing. The dissimilar particle properties at the overlap regions are the reason for the different CNT heights. These differences in the catalytic particles properties are caused by the lower laser fluence at the mask edges and the interaction of the laser plasma plume with the pristine nitride film.

  16. Magnetic properties of core-shell catalyst nanoparticles for carbon nanotube growth

    Science.gov (United States)

    Fleaca, C. T.; Morjan, I.; Alexandrescu, R.; Dumitrache, F.; Soare, I.; Gavrila-Florescu, L.; Le Normand, F.; Derory, A.

    2009-03-01

    Two types of core-shell nanoparticles have been prepared by laser pyrolysis using Fe(CO) 5 and C 2H 2 or [(CH 3) 3Si] 2O as precursors and C 2H 4 as sensitizer. The first type (about 4 nm diameter) - produced by the decomposition of Fe(CO) 5 in the presence of C 2H 4 and C 2H 2 - consists of Fe cores protected by graphenic layers. The second type (mean particle size of about 14 nm) consists also of Fe cores, yet covered by few nm thick γ-Fe 2O 3/porous polycarbosiloxane shells resulted from the [(CH 3) 3Si] 2O decomposition and superficial oxidation after air exposure. The hysteresis loops suggest a room temperature superparamagnetic behavior of the Fe-C nanopowder and a weak ferromagnetic one for larger particles in the Fe-Fe 2O 3-polymer sample. Both types of nanoparticles were finally used as a catalyst for the carbon nanotube growth by seeding Si(100) substrates via drop-casting method. CNTs were grown by Hot-Filament Direct. Current PE CVD technique from C 2H 2 and H 2 at 980 K. It is suggested that the increased density and orientation degree observed for the multiwall nanotubes grown from Fe-Fe 2O 3-polymer nanoparticles could be due to their magnetic behavior and surface composition.

  17. Effect of Substrate Morphology on Growth and Field Emission Properties of Carbon Nanotube Films

    Directory of Open Access Journals (Sweden)

    Kumar Vikram

    2008-01-01

    Full Text Available AbstractCarbon nanotube (CNT films were grown by microwave plasma-enhanced chemical vapor deposition process on four types of Si substrates: (i mirror polished, (ii catalyst patterned, (iii mechanically polished having pits of varying size and shape, and (iv electrochemically etched. Iron thin film was used as catalytic material and acetylene and ammonia as the precursors. Morphological and structural characteristics of the films were investigated by scanning and transmission electron microscopes, respectively. CNT films of different morphology such as vertically aligned, randomly oriented flowers, or honey-comb like, depending on the morphology of the Si substrates, were obtained. CNTs had sharp tip and bamboo-like internal structure irrespective of growth morphology of the films. Comparative field emission measurements showed that patterned CNT films and that with randomly oriented morphology had superior emission characteristics with threshold field as low as ~2.0 V/μm. The defective (bamboo-structure structures of CNTs have been suggested for the enhanced emission performance of randomly oriented nanotube samples.

  18. Organic modification of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The organic modification of carbon nanotubes is a novel research field being developed recently. In this article, the history and newest progress of organic modification of carbon nanotubes are reviewed from two aspects:organic covalent modification and organic noncovalent modification of carbon nanotubes. The preparation and properties of organic modified carbon nanotubes are discussed in detail. In addition, the prospective development of organic modification of carbon nanotubes is suggested.

  19. Solid source growth of Si oxide nanowires promoted by carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Congxiang [CINTRA CNRS/NTU/THALES, Nanyang Technological University, Singapore 637553 (Singapore); Novitas, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Liu, Wen-wen; Wang, Xingli [Novitas, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Li, Xiaocheng [Laboratory of clean energy chemistry and materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18 Tianshui Middle Road, Lanzhou 730000 (China); Tan, Chong Wei [CINTRA CNRS/NTU/THALES, Nanyang Technological University, Singapore 637553 (Singapore); Novitas, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Tay, Beng Kang, E-mail: ebktay@ntu.edu.sg [CINTRA CNRS/NTU/THALES, Nanyang Technological University, Singapore 637553 (Singapore); Novitas, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Coquet, Philippe [CINTRA CNRS/NTU/THALES, Nanyang Technological University, Singapore 637553 (Singapore)

    2014-09-30

    Highlights: • An array of well aligned and uniform CNTs is successfully fabricated by PECVD. • SiONW growth utilizes Si substrate as the source, ruling out the usage of silane. • With CNT array on the substrate, SiONW growth is improved significantly. • CNTs help dispersion of the catalysts and diffusion of the Si atoms. - Abstract: We report a method to promote solid source growth of Si oxide nanowires (SiONWs) by using an array of vertically aligned carbon nanotubes (CNTs). It starts with the fabrication of CNT array by plasma enhanced chemical vapor deposition (PECVD) on Si wafers, followed by growth of SiONWs. Herein, CNTs serve as a scaffold, which helps the dispersion of catalysts for SiONWs and also provides space for hydrogen which boosts the diffusion of Si atoms and hence formation of SiONWs. As the result, a three dimensional (3D) hybrid network of densely packed SiONWs and CNTs can be produced rapidly.

  20. Effect of ammonia gas etching on growth of vertically aligned carbon nanotubes/nanofibers

    Institute of Scientific and Technical Information of China (English)

    Sang-Gook KIM; Sooh-Yung KIM; Hytmg-Woo LEE

    2011-01-01

    The etching effect of ammonia (NH3) on the growth of vertically aligned nanotubes/nanofibers (CNTs) was investigated by direct-current plasma enhanced chemical vapor deposition (DC-PECVD). NH3 gas etches Ni catalyst layer to form nanoscale islands while NH3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH3 gas etchingis different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth. the single strand CNT growth requires shorter etching time (5 min) than large catalytic patterns (10 min) since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy (HTEM) shows fishbone structure of CNTs grown by PECVD.

  1. Isolated crater formation by gas cluster ion impact and their use as templates for carbon nanotube growth

    Energy Technology Data Exchange (ETDEWEB)

    Toyoda, Noriaki, E-mail: ntoyoda@incub.u-hyogo.ac.jp; Kimura, Asahi; Yamada, Isao

    2016-03-15

    Crater-like defects formations with gas cluster ion beams (GCIB) were used as templates for carbon nanotube (CNT) growth. Upon a gas cluster ion impact, dense energy is deposited on a target surface while energy/atom of gas cluster ion is low, which creates crater-like defects. Si and SiO{sub 2} were irradiated with Ar-GCIB, subsequently CNTs were grown with an alcohol catalytic CVD using Co and ethanol as catalyst and precursor, respectively. From SEM, AFM and Raman spectroscopy, it was shown that growth of CNT with small diameter was observed on SiO{sub 2} with Ar-GCIB irradiation. On Si targets, formation of craters with bottom oxide prevented Co diffusion during CNT growth, as a result, CNT growth was observed only on Si irradiated with high-energy Ar-GCIB. These results showed that isolated defects created by GCIB can be used as templates for nanotube growth.

  2. Low-temperature growth of multi-walled carbon nanotubes by thermal CVD

    Energy Technology Data Exchange (ETDEWEB)

    Halonen, Niina; Leino, Anne-Riikka; Maeklin, Jani; Kukkola, Jarmo; Toth, Geza [Microelectronics and Materials Physics Laboratories, University of Oulu (Finland); Sapi, Andras; Nagy, Laszlo; Puskas, Robert; Kukovecz, Akos; Konya, Zoltan [Department of Applied and Environmental Chemistry, University of Szeged (Hungary); Wu, Ming-Chung; Liao, Hsueh-Chung; Su, Wei-Fang [Department of Materials Science and Engineering, National Taiwan University, Taipei (China); Shchukarev, Andrey; Mikkola, Jyri-Pekka [Department of Chemistry, Institute of Technical Chemistry, Chemical-Biological Center, Umeaa University (Sweden); Kordas, Krisztian [Microelectronics and Materials Physics Laboratories, University of Oulu (Finland); Department of Chemistry, Institute of Technical Chemistry, Chemical-Biological Center, Umeaa University (Sweden)

    2011-11-15

    Low-temperature thermal chemical vapor deposition (thermal CVD) synthesis of multi-walled carbon nanotubes (MWCNTs) was studied using a large variety of different precursor compounds. Cyclopentene oxide, tetrahydrofuran, methanol, and xylene:methanol mixture as oxygen containing heteroatomic precursors, while xylene and acetylene as conventional hydrocarbon feedstocks were applied in the experiments. The catalytic activity of Co, Fe, Ni, and their bi- as well as tri-metallic combinations were tested for the reactions. Low-temperature CNT growth occurred at 400 C when using bi-metallic Co-Fe and tri-metallic Ni-Co-Fe catalyst (on alumina) and methanol or acetylene as precursors. In the case of monometallic catalyst nanoparticles, only Co (both on alumina and on silica) was found to be active in the low temperature growth (below 500 C) from oxygenates such as cyclopentene oxide and methanol. The structure and composition of the achieved MWCNTs products were studied by scanning and transmission electron microscopy (SEM and TEM) as well as by Raman and X-ray photoelectron spectroscopy (XPS) and by X-ray diffraction (XRD). The successful MWCNT growth below 500 C is promising from the point of view of integrating MWCNT materials into existing IC fabrication technologies. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    Science.gov (United States)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  4. Multi-Directional Growth of Aligned Carbon Nanotubes Over Catalyst Film Prepared by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Zhou Kai

    2010-01-01

    Full Text Available Abstract The structure of vertically aligned carbon nanotubes (CNTs severely depends on the properties of pre-prepared catalyst films. Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD was employed to deposit uniform Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology. The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future.

  5. In-situ localized carbon nanotube growth inside partially sealed enclosures

    Directory of Open Access Journals (Sweden)

    Y. van de Burgt

    2013-09-01

    Full Text Available Carbon nanotube assemblies can be used for specific applications such as sensors and filters. We present a method and proof-of-concept to directly grow vertically-aligned carbon nanotube structures within sealed enclosures by means of a feedback-controlled laser-assisted chemical vapor deposition technique. The process is compatible with a variety of micro-fabrication processes and bypasses the need for post-process packaging. Our experiments raise interesting observations related to the gas diffusion dynamics in micro-scale and sub-micron enclosures.

  6. Epitaxial Approaches to Carbon Nanotube Organization

    Science.gov (United States)

    Ismach, Ariel

    Carbon nanotubes have unique electronic, mechanical, optical and thermal properties, which make them ideal candidates as building blocks in nano-electronic and electromechanical systems. However, their organization into well-defined geometries and arrays on surfaces remains a critical challenge for their integration into functional nanosystems. In my PhD, we developed a new approach for the organization of carbon nanotubes directed by crystal surfaces. The principle relies on the guided growth of single-wall carbon nanotubes (SWNTs) by atomic features presented on anisotropic substrates. We identified three different modes of surface-directed growth (or 'nanotube epitaxy'), in which the growth of carbon nanotubes is directed by crystal substrates: We first observed the nanotube unidirectional growth along atomic steps ('ledge-directed epitaxy') and nanofacets ('graphoepitaxy') on the surface of miscut C-plane sapphire and quartz. The orientation along crystallographic directions ('lattice-directed epitaxy') was subsequently observed by other groups on different crystals. We have proposed a "wake growth" mechanism for the nanotube alignment along atomic steps and nanofacets. In this mechanism, the catalyst nanoparticle slides along the step or facet, leaving the nanotube behind as a wake. In addition, we showed that the combination of surface-directed growth with external forces, such as electric-field and gas flow, can lead to the simultaneous formation of complex nanotube structures, such as grids and serpentines. The "wake growth" model, which explained the growth of aligned nanotubes, could not explain the formation of nanotube serpentines. For the latter, we proposed a "falling spaghetti" mechanism, in which the nanotube first grows by a free-standing process, aligned in the direction of the gas flow, then followed by absorption on the stepped surface in an oscillatory manner, due to the competition between the drag force caused by the gas flow on the suspended

  7. Study on Diameter Controlled Growth of Carbon Nanotubes by LaAl1-xFexO3 Catalysts

    Institute of Scientific and Technical Information of China (English)

    PENG Feng; WANG Hong-juan

    2005-01-01

    A series of LaAl1-xFexO3 catalysts prepared with lanthanum nitrate, aluminium nitrate and iron nitrate was investigated in catalytical syntheses of carbon nanotubes with high yields and purity. The properties of carbon nanotubes prepared by the method of CVD(chemical vapor deposition) with n-hexane as the carbon resource were studied and it was shown that the diameter of carbon nanotubes can be controlled by the molar ratio of iron to aluminum in the catalysts and that the diameter of carbon nanotubes changes a little with the decrease of the iron content in the catalysts. From the TEM pictures of carbon nanotubes, it can be found that the LaAl1-xFexO3 catalysts have a significant influence on the wall thickness of the carbon nanotubes, whereas they have little influence on the inner diameter of the carbon nanotubes.

  8. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.;

    2008-01-01

    an important insight in the energetics and stability of nanotubes of different chirality and might be important for the understanding of nanotube growth process. For the computations we use empirical Brenner and Tersoff potentials and discuss their applicability to the study of carbon nanotubes. From......In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms...... are known. The parameters of the liquid surface model and its potential applications are discussed. The model has been suggested for open end and capped nanotubes. The influence of the catalytic nanoparticle, atop which nanotubes grow, on the nanotube stability is also discussed. The suggested model gives...

  9. Carbon nanotube solar cells.

    Directory of Open Access Journals (Sweden)

    Colin Klinger

    Full Text Available We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.

  10. CONTROLLED GROWTH OF CARBON NANOTUBES ON CONDUCTIVE METAL SUBSTRATES FOR ENERGY STORAGE APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.; Engtrakul, C.

    2009-01-01

    The impressive mechanical and electronic properties of carbon nanotubes (CNTs) make them ideally suited for use in a variety of nanostructured devices, especially in the realm of energy production and storage. In particular, vertically-aligned CNT “forests” have been the focus of increasing investigation for use in supercapacitor electrodes and as hydrogen adsorption substrates. Vertically-aligned CNT growth was attempted on metal substrates by waterassisted chemical vapor deposition (CVD). CNT growth was catalyzed by iron-molybdenum (FeMo) nanoparticle catalysts synthesized by a colloidal method, which were then spin-coated onto Inconel® foils. The substrates were loaded into a custom-built CVD apparatus, where CNT growth was initiated by heating the substrates to 750 °C under the fl ow of He, H2, C2H4 and a controlled amount of water vapor. The resultant CNTs were characterized by a variety of methods including Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and the growth parameters were varied in an attempt to optimize the purity and growth yield of the CNTs. The surface area and hydrogen adsorption characteristics of the CNTs were quantifi ed by the Brunauer- Emmett-Teller (BET) and Sieverts methods, and their capacitance was measured via cyclic voltammetry. While vertically-aligned CNT growth could not be verifi ed, TEM and SEM analysis indicated that CNT growth was still obtained, resulting in multiwalled CNTs of a wide range in diameter along with some amorphous carbon impurities. These microscopy fi ndings were reinforced by Raman spectroscopy, which resulted in a G/D ratio ranging from 1.5 to 3 across different samples, suggestive of multiwalled CNTs. Changes in gas fl ow rates and water concentration during CNT growth were not found to have a discernable effect on the purity of the CNTs. The specifi c capacitance of a CNT/FeMo/Inconel® electrode was found to be 3.2 F/g, and the BET surface area of

  11. Inkjet Printing of Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Ryan P. Tortorich

    2013-07-01

    Full Text Available In an attempt to give a brief introduction to carbon nanotube inkjet printing, this review paper discusses the issues that come along with preparing and printing carbon nanotube ink. Carbon nanotube inkjet printing is relatively new, but it has great potential for broad applications in flexible and printable electronics, transparent electrodes, electronic sensors, and so on due to its low cost and the extraordinary properties of carbon nanotubes. In addition to the formulation of carbon nanotube ink and its printing technologies, recent progress and achievements of carbon nanotube inkjet printing are reviewed in detail with brief discussion on the future outlook of the technology.

  12. Alignment controlled growth of single-walled carbon nanotubes on quartz substrates.

    Science.gov (United States)

    Xiao, Jianliang; Dunham, Simon; Liu, Ping; Zhang, Yongwei; Kocabas, Coskun; Moh, Lionel; Huang, Yonggang; Hwang, Keh-Chih; Lu, Chun; Huang, Wei; Rogers, John A

    2009-12-01

    Single-walled carbon nanotubes (SWNTs) possess extraordinary electrical properties, with many possible applications in electronics. Dense, horizontally aligned arrays of linearly configured SWNTs represent perhaps the most attractive and scalable way to implement this class of nanomaterial in practical systems. Recent work shows that templated growth of tubes on certain crystalline substrates yields arrays with the necessary levels of perfection, as demonstrated by the formation of devices and full systems on quartz. This paper examines advanced implementations of this process on crystalline quartz substrates with different orientations, to yield strategies for forming diverse, but well-defined horizontal configurations of SWNTs. Combined experimental and theoretical studies indicate that angle-dependent van der Waals interactions can account for nearly all aspects of alignment on quartz with X, Y, Z, and ST cuts, as well as quartz with disordered surface layers. These findings provide important insights into methods for guided growth of SWNTs, and possibly other classes of nanomaterials, for applications in electronics, sensing, photodetection, light emission, and other areas.

  13. Growth, dispersion, and electronic devices of nitrogen-doped single-wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Oikonomou, Antonios [School of Computer Science, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Susi, Toma; Kauppinen, Esko I. [Nanomaterials Group, Department of Applied Physics, Aalto University School of Science, PO Box 15100, 00076 Aalto (Finland); Vijayaraghavan, Aravind [School of Computer Science, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Centre for Mesoscience and Nanotechnology, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)

    2012-12-15

    This paper describes the complete processes from growth to electronic devices of nitrogen-doped single-wall carbon nanotubes (N-SWCNTs). The N-SWCNTs were synthesized using a floating catalyst chemical vapor deposition method. The dry-deposited N-SWCNT films were dispersed in N-methylpyrolidone followed by sonication and centrifugation steps to yield a stable dispersion of N-SWCNTs in solution. The length and diameter distribution as well as concentration of N-SWCNTs in solution were measured by atomic force microscopy and optical absorption spectroscopy, respectively. The N-SWCNTs were then assembled into electronic devices using bottom-up dielectrophoresis and characterized as field-effect transistors. Finally, the potential for application of N-SWCNTs in sensors is discussed. The three stages of N-doped SWCNT processing: (a) growth and collection on filter, (b) dispersion in NMP, and (c) dielectrophoretic assembly into transistor device. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Direct-growth carbon nanotubes on 3D structural microelectrodes for electrophysiological recording.

    Science.gov (United States)

    Pan, Alice Ian; Lin, Min-Hsuan; Chung, Hui-Wen; Chen, Hsin; Yeh, Shih-Rung; Chuang, Yung-Jen; Chang, Yen-Chung; Yew, Tri-Rung

    2016-01-01

    A novel 3D carbon nanotube (CNT) microelectrode was developed through direct growth of CNTs on a gold pin-shaped 3D microelectrode at a low temperature (400 °C) for applications in neural and cardiac recording. With an electroplated Ni catalyst layer covering the entire surface of the pin-shaped structure, CNTs were synthesized on a 3D microelectrode by catalytic thermal chemical vapor deposition (CVD). According to the analyses by electrochemical impedance spectroscopy, the impedance of 3D microelectrodes after CNT growth and UV/O3 treatment decreased from 9.3 Ω mm(-2) to 1.2 Ω mm(-2) and the capacitance increased largely from 2.2 mF cm(-2) to 73.3 mF cm(-2). The existence of UVO3-treated CNT led to a large improvement of interfacial capacitance, contributing to the decrease of impedance. The electrophysiological detection capability of this 3D CNT microelectrode was demonstrated by the distinguished P waves, QRS complex and T waves in the electrocardiogram of the zebrafish heart and the action potential recorded from individual rat hippocampal neurons. The compatibility of integration with ICs, high resolution in space, electrophysiological signals, and non-invasive long-term recording suggest that the 3D CNT microelectrode exhibits promising potential for applications in electrophysiological research and clinical trials.

  15. Effects of a carbon nanotube-collagen coating on a titanium surface on osteoblast growth

    Science.gov (United States)

    Park, Jung Eun; Park, Il-Song; Neupane, Madhav Prasad; Bae, Tae-Sung; Lee, Min-Ho

    2014-02-01

    This study was performed to evaluate the effect of collagen-multi-walled carbon nanotubes (MWCNTs) composite coating deposited on titanium on osteoblast growth. Titanium samples coated with only collagen and MWCNTs were used as controls. Pure titanium was coated with collagen-MWCNTs composite coating with 5, 10 and 20 μg cm-2 MWCNTs by dip coating method. Scanning probe microscopy, field emission scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy were used to ascertain the root mean squared roughness, structural and morphological features and, the interaction between the collagen and the MWCNTs, respectively. The biocompatibility of the collagen-MWCNTs composite coated Ti was assessed by MTT and ALP activity assays after culturing the cells for 2 and 5 days. The study reveals that root mean squared surface roughness of collagen-MWCNTs composite coated titanium is relatively higher than those of collagen and MWCNTs coated Ti. There is a strong interaction between the MWCNTs and the collagen, which is supported by the inferences made in FE-SEM and TEM studies and further confirmed by FT-IR spectra. Among all the specimens tested, cell proliferation is relatively higher on collagen-MWCNTs composite coated Ti specimen incorporated with 20 μg cm-2 of MWCNTs (p collagen-MWCNTs composite coated Ti specimens is considered responsible for the relatively higher extent of cell proliferation. The MWCNTs incorporated in the composite could have also contributed to the cell viability and growth.

  16. Polyethyleneimine functionalized single-walled carbon nanotubes as a substrate for neuronal growth.

    Science.gov (United States)

    Hu, Hui; Ni, Yingchun; Mandal, Swadhin K; Montana, Vedrana; Zhao, Bin; Haddon, Robert C; Parpura, Vladimir

    2005-03-17

    We report the synthesis of a single-walled carbon nanotube (SWNT) graft copolymer. This polymer was prepared by the functionalization of SWNTs with polyethyleneimine (PEI). We used this graft copolymer, SWNT-PEI, as a substrate for cultured neurons and found that it promotes neurite outgrowth and branching.

  17. Influence of carrier gas flow rate on carbon nanotubes growth by TCVD with Cu catalyst

    Directory of Open Access Journals (Sweden)

    S.A. Khorrami

    2016-07-01

    Full Text Available Carbon nanotubes (CNTs were grown on copper catalyst by thermal chemical vapor deposition (TCVD using H2 and N2 as carrier gases. CNTs with different morphologies were observed using different carrier gas flow rates. The influence of carrier gas flow rates on the structure of carbon nanotubes was compared. Catalyst nanolayer was sputtered on mirror polished silicon wafers. The catalyst film thickness was determined by using the Rutherford Back Scattering (RBS technique. Ethanol as carbon source has been used. The surface morphology and nanostructure were studied by Scanning Electron Microscopy (SEM, Raman Spectroscopy, Tunneling Electron Microscopy (TEM and Atomic Force Microscopy (AFM. Results indicated that the amounts of deposited carbon decrease with increasing flow rates. These results showed that CNTs’ length decreased with increasing flow rates. Results suggest that Cu nanolayer is suitable as catalyst due to the fact that CNTs are monotonous.

  18. Engineering the Activity and Lifetime of Heterogeneous Catalysts for Carbon Nanotube Growth via Substrate Ion Beam Bombardment (Postprint)

    Science.gov (United States)

    2014-07-31

    11,25 and chirality.19,20 CNTs are grown via heterogeneous catalysis using a thin film of catalyst on a wide variety of catalyst supports. Films of...another method in catalysis science to engineer supports to enhance both catalytic activity and lifetime with general implications for heterogeneous ...AFRL-RX-WP-JA-2014-0159 ENGINEERING THE ACTIVITY AND LIFETIME OF HETEROGENEOUS CATALYSTS FOR CARBON NANOTUBE GROWTH VIA SUBSTRATE ION BEAM

  19. Growth of carbon nanotubes on fully processed silicon-on-insulator CMOS substrates.

    Science.gov (United States)

    Haque, M Samiul; Ali, S Zeeshan; Guha, P K; Oei, S P; Park, J; Maeng, S; Teo, K B K; Udrea, F; Milne, W I

    2008-11-01

    This paper describes the growth of Carbon Nanotubes (CNTs) both aligned and non-aligned on fully processed CMOS substrates containing high temperature tungsten metallization. While the growth method has been demonstrated in fabricating CNT gas sensitive layers for high temperatures SOI CMOS sensors, it can be employed in a variety of applications which require the use of CNTs or other nanomaterials with CMOS electronics. In our experiments we have grown CNTs both on SOI CMOS substrates and SOI CMOS microhotplates (suspended on membranes formed by post-CMOS deep RIE etching). The fully processed SOI substrates contain CMOS devices and circuits and additionally, some wafers contained high current LDMOSFETs and bipolar structures such as Lateral Insulated Gate Bipolar Transistors. All these devices were used as test structures to investigate the effect of additional post-CMOS processing such as CNT growth, membrane formation, high temperature annealing, etc. Electrical characterisation of the devices with CNTs were performed along with SEM and Raman spectroscopy. The CNTs were grown both at low and high temperatures, the former being compatible with Aluminium metallization while the latter being possible through the use of the high temperature CMOS metallization (Tungsten). In both cases we have found that there is no change in the electrical behaviour of the CMOS devices, circuits or the high current devices. A slight degradation of the thermal performance of the CMOS microhotplates was observed due to the extra heat dissipation path created by the CNT layers, but this is expected as CNTs exhibit a high thermal conductance. In addition we also observed that in the case of high temperature CNT growth a slight degradation in the manufacturing yield was observed. This is especially the case where large area membranes with a diameter in excess of 500 microns are used.

  20. Laser printing of nanoparticle toner enables digital control of micropatterned carbon nanotube growth.

    Science.gov (United States)

    Polsen, Erik S; Stevens, Adam G; Hart, A John

    2013-05-01

    Commercialization of materials utilizing patterned carbon nanotube (CNT) forests, such as hierarchical composite structures, dry adhesives, and contact probe arrays, will require catalyst patterning techniques that do not rely on cleanroom photolithography. We demonstrate the large scale patterning of CNT growth catalyst via adaptation of a laser-based electrostatic printing process that uses magnetic ink character recognition (MICR) toner. The MICR toner contains iron oxide nanoparticles that serve as the catalyst for CNT growth, which are printed onto a flexible polymer (polyimide) and then transferred to a rigid substrate (silicon or alumina) under heat and mechanical pressure. Then, the substrate is processed for CNT growth under an atmospheric pressure chemical vapor deposition (CVD) recipe. This process enables digital control of patterned CNT growth via the laser intensity, which controls the CNT density; and via the grayscale level, which controls the pixelation of the image into arrays of micropillars. Moreover, virtually any pattern can be designed using standard software (e.g., MS Word, AutoCAD, etc.) and printed on demand. Using a standard office printer, we realize isolated CNT microstructures as small as 140 μm and isolated catalyst ″pixels″ as small as 70 μm (one grayscale dot) and determine that individual toner microparticles result in features of approximately 5-10 μm . We demonstrate that grayscale CNT patterns can function as dry adhesives and that large-area catalyst patterns can be printed directly onto metal foils or transferred to ceramic plates. Laser printing therefore shows promise to enable high-speed micropatterning of nanoparticle-containing thin films under ambient conditions, possibly for a wide variety of nanostructures by engineering of toners containing nanoparticles of desired composition, size, and shape.

  1. Preparation and properties of in-situ growth of carbon nanotubes reinforced hydroxyapatite coating for carbon/carbon composites.

    Science.gov (United States)

    Liu, Shoujie; Li, Hejun; Su, Yangyang; Guo, Qian; Zhang, Leilei

    2017-01-01

    Carbon nanotubes (CNTs) possess excellent mechanical properties for their role playing in reinforcement as imparting strength to brittle hydroxyapatite (HA) bioceramic coating. However, there are few reports relating to the in-situ grown carbon nanotubes reinforced hydroxyapatite (CNTs-HA) coating. Here we demonstrate the potential application in reinforcing biomaterials by an attempt to use in-situ grown of CNTs strengthen HA coating, using a combined method composited of injection chemical vapor deposition (ICVD) and pulsed electrodeposition. The microstructure, phases and chemical compositions of CNTs-HA coatings were characterized by various advanced methods. The scanning electron microscopy (SEM) images indicated that CNTs-HA coatings avoided the inhomogeneous dispersion of CNTs inside HA coating. The result show that the interfacial shear strength between CNTs-HA coating and the C/C composite matrix reaches to 12.86±1.43MPa. Potenitodynamic polarization and electrochemical impedance spectroscopy (EIS) studies show that the content of CNTs affects the corrosion resistance of CNTs-HA coating. Cell culturing and simulated body fluid test elicit the biocompatibility with living cells and bioactivity of CNTs-HA coatings, respectively.

  2. Effect of Catalyst Film Thickness on Growth Morphology, Surface Wettability and Drag Reduction Property of Carbon Nanotubes

    Science.gov (United States)

    Ma, Weiwei; Zhou, Zhiping; Li, Gang; Li, Ping

    2016-10-01

    Nickel films were deposited on silicon substrates using magnetron sputtering method. The pretreatment process of nickel films under high temperature and ammonia atmosphere was investigated. The thickness of nickel film has a great influence on growth morphology of carbon nanotubes (CNTs). Too large or too small thickness would do harm to the orientated growth of CNTs. The inner structure, elements composition and growth mechanism have been confirmed by TEM and EDX characterization. The surface wettability and drag reduction property of CNTs were investigated. This paper can provide a new, effective method to further develop the practical application in micro/nano devices field.

  3. Growth of carbon nanotubes by Fe-catalyzed chemical vapor processes on silicon-based substrates

    Science.gov (United States)

    Angelucci, Renato; Rizzoli, Rita; Vinciguerra, Vincenzo; Fortuna Bevilacqua, Maria; Guerri, Sergio; Corticelli, Franco; Passini, Mara

    2007-03-01

    In this paper, a site-selective catalytic chemical vapor deposition synthesis of carbon nanotubes on silicon-based substrates has been developed in order to get horizontally oriented nanotubes for field effect transistors and other electronic devices. Properly micro-fabricated silicon oxide and polysilicon structures have been used as substrates. Iron nanoparticles have been obtained both from a thin Fe film evaporated by e-gun and from iron nitrate solutions accurately dispersed on the substrates. Single-walled nanotubes with diameters as small as 1 nm, bridging polysilicon and silicon dioxide “pillars”, have been grown. The morphology and structure of CNTs have been characterized by SEM, AFM and Raman spectroscopy.

  4. The Pattern Growth of Carbon Nanotubes by Self-assembled Monolayers Techniques

    Institute of Scientific and Technical Information of China (English)

    KUO Chengtzu; KUO Deshan; CHEN Polin

    2004-01-01

    The well controllable selective growth of carbon nanotubes (CNTs)on the desired area is an important issue for their future applications. In this study, a novel method for selective growth of CNTs was proposed by using the technology of self-assembly monolayers (SAMs) and the Fe-assisted CNTs growth. The Si wafers with the a: Si/Si3N4 layer patterns were first prepared by low pressure chemical vapor deposition (LPCVD)and lithography techniques to act as the substrates for selective deposition of SAMs. The selectivity of SAMs from APTMS solution (N-(2-aminoethyl)-3-aminopropyltrimethoxsilane) is based on its greater reactivity of head group on a-Si than Si3N4 films. The areas of pattern with SAMs will first chelate the Fe3+ ions by their diamine-terminated group. The Fe3+ ions were then consolidated to become Fe-hydroxides in sodium boron hydride solution to form the Fe-hydroxides pattern. Finally, the Fe-hydroxides pattern was pretreated in H plasma to become a well-distributed Fe nano-particles on the surface, and followed by CNTs deposition using Fe as catalyst in a microwave plasma-chemical vapor deposition (MP-CVD) system to become the CNTs pattern. The products in each processing step, including microstructures and lattice images of CNTs, were characterized by contact angle measurements, scanning electron microscopy(SEM), XPS, Auger spectroscopy, transmission electron microscopy (TEM) and high resolution TEM (HRTEM)deposition. The results show that the main process parameters include the surface activation process and its atmosphere, consolidation time and temperature, H plasma pretreatment. The function of each processing step will be discussed.

  5. The Pattern Growth of Carbon Nanotubes by Self-assembled Monolayers Techniques

    Institute of Scientific and Technical Information of China (English)

    KUO Chengtzu; KUO Deshan; CHEN Polin

    2004-01-01

    The well controllable selective growth of carbon nanotubes (CNTs)on the desired area is an important issue for their future applications. In this study, a novel method for selective growth of CNTs was proposed by using the technology of self-assembly monolayers (SAMs) and the Fe-assisted CNTs growth. The Si wafers with the a : Si/Si3N4 layer patterns were first prepared by low pressure chemical vapor deposition (LPCVD)and lithography techniques to act as the substrates for selective deposition of SAMs. The selectivity of SAMs from APTMS solution (N-(2-aminoethyl)-3-aminopropyltrimethoxsilane) is based on its greater reactivity of head group on a-Si than Si3N4 films. The areas of pattern with SAMs will first chelate the Fe3+ ions by their diamine-terminated group. The Fe3+ ions were then consolidated to become Fe-hydroxides in sodium boron hydride solution to form the Fe-hydroxides pattern. Finally, the Fe-hydroxides pattern was pretreated in H plasma to become a well-distributed Fe nano-particles on the surface, and followed by CNTs deposition using Fe as catalyst in a microwave plasma-chemical vapor deposition (MP-CVD) system to become the CNTs pattern. The products in each processing step, including microstructures and lattice images of CNTs, were characterized by contact angle measurements, scanning electron microscopy (SEM), XPS, Auger spectroscopy, transmission electron microscopy (TEM) and high resolution TEM (HRTEM)deposition. The results show that the main process parameters include the surface activation process and its atmosphere, consolidation time and temperature, H plasma pretreatment. The function of each processing step will be discussed.

  6. Low-temperature catalyst activator: mechanism of dense carbon nanotube forest growth studied using synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Akito Takashima

    2014-07-01

    Full Text Available The mechanism of the one-order-of-magnitude increase in the density of vertically aligned carbon nanotubes (CNTs achieved by a recently developed thermal chemical vapor deposition process was studied using synchrotron radiation spectroscopic techniques. In the developed process, a Ti film is used as the underlayer for an Fe catalyst film. A characteristic point of this process is that C2H2 feeding for the catalyst starts at a low temperature of 450°C, whereas conventional feeding temperatures are ∼800°C. Photoemission spectroscopy using soft and hard X-rays revealed that the Ti underlayer reduced the initially oxidized Fe layer at 450°C. A photoemission intensity analysis also suggested that the oxidized Ti layer at 450°C behaved as a support for nanoparticle formation of the reduced Fe, which is required for dense CNT growth. In fact, a CNT growth experiment, where the catalyst chemical state was monitored in situ by X-ray absorption spectroscopy, showed that the reduced Fe yielded a CNT forest at 450°C. Contrarily, an Fe layer without the Ti underlayer did not yield such a CNT forest at 450°C. Photoemission electron microscopy showed that catalyst annealing at the conventional feeding temperature of 800°C caused excess catalyst agglomeration, which should lead to sparse CNTs. In conclusion, in the developed growth process, the low-temperature catalyst activation by the Ti underlayer before the excess Fe agglomeration realised the CNT densification.

  7. Growth of multi-amine terminated poly(amidoamine) dendrimers on the surface of carbon nanotubes

    Science.gov (United States)

    Pan, Bifeng; Cui, Daxiang; Gao, Feng; He, Rong

    2006-05-01

    An in situ repetitive divergent polymerization strategy was employed to grow multi-amine poly(amidoamine) dendritic macromolecules on the surfaces of multiwalled carbon nanotubes (MWNTs), affording novel three-dimensional (3D) molecular nanocomposites. The crude MWNTs were oxidized using H2SO4/HNO3 = 3:1 (v/v) and then reacted with thionyl chloride, resulting in MWNTs functionalized with chlorocarbonyl groups (MWNT-COCl). MWNT-COCl, when reacted with an excess of ethylenediamine, produced amine-functionalized MWNT supported initiators (MWNT-NH2). Using the MWNT-NH2 as the growth supporter and methylacrylate/ethylenediamine as building blocks, multi-amine dendritic poly(amidoamine) macromolecules were covalently grafted onto the sidewalls and ends of MWNTs via Michael addition reaction and amidation. Thermal gravimetric analysis (TGA) measurements showed that the weight ratio of the as-grown dendritic polymers on the MWNT surfaces lay in the 10%-50% range. The products were also characterized by Fourier transform infrared (FTIR), Raman, nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM) analysis. The results indicate that the dendrimers are grafted onto the surface of MWNTs. The as-prepared nanocomposites exhibit excellent dispersibility in water.

  8. Effects of laminin-coated carbon nanotube/chitosan fibers on guided neurite growth.

    Science.gov (United States)

    Huang, Yi-Cheng; Hsu, Sung-Hao; Kuo, Wen-Chun; Chang-Chien, Cheng-Lun; Cheng, Henrich; Huang, Yi-You

    2011-10-01

    This study assesses the ability and potential of carbon nanotube (CNT)/chitosan to guide axon re-growth after nerve injuries. The CNT/chitosan fibers were produced via the coagulation and hydrodynamic focusing method. Fiber width and morphology were adjusted using such parameters as syringe pumping rate and the coagulant used. The CNT/chitosan fiber diameters were 50-300 μm for syringe pumping rates of 6-48 mL/h. Polyethylene glycol/NaOH (25%, w/w) solution was a suitable coagulant for forming fibers with small diameters. Physical property tests demonstrate that the CNT/chitosan composites had superior tensile strength and electrical conductivity compared with those of chitosan alone. The MTT and LDH tests reveal that CNT/chitosan composites were not cytotoxic. To improve the neural cell affinity of CNT/chitosan fibers, laminin was incorporated onto fiber surfaces via the oxygen plasma technique; cell adhesion ratio increased significantly from 3.5% to 72.2% with this surface modification. Immunofluorescence staining and SEM imaging indicate that PC12 cells adhered successfully and grew on the laminin (LN)-coated CNT/chitosan films and fibers. Experimental results show that PC12 grown on LN-coated CNT/chitosan fibers in vitro extend longitudinally oriented neurites in a manner similar to that of native peripheral nerves. With the inherent electrical properties of CNTs, oriented CNT/chitosan fibers have a potential for use as nerve conduits in nerve tissue engineering.

  9. Growth control of carbon nanotubes using by anodic aluminum oxide nano templates.

    Science.gov (United States)

    Park, Yong Seob; Choi, Won Seek; Yi, Junsin; Lee, Jaehyeong

    2014-05-01

    Anodic Aluminum Oxide (AAO) template prepared in acid electrolyte possess regular and highly anisotropic porous structure with pore diameter range from five to several hundred nanometers, and with a density of pores ranging from 10(9) to 10(11) cm(-2). AAO can be used as microfilters and templates for the growth of CNTs and metal or semiconductor nanowires. Varying anodizing conditions such as temperature, electrolyte, applied voltage, anodizing and widening time, one can control the diameter, the length, and the density of pores. In this work, we deposited Al thin film by radio frequency magnetron sputtering method to fabricate AAO nano template and synthesized multi-well carbon nanotubes on a glass substrate by microwave plasma-enhanced chemical vapor deposition (MPECVD). AAO nano-porous templates with various pore sizes and depths were introduced to control the dimension and density of CNT arrays. The AAO nano template was synthesize on glass by two-step anodization technique. The average diameter and interpore distance of AAO nano template are about 65 nm and 82 nm. The pore density and AAO nano template thickness are about 2.1 x 10(10) pores/cm2 and 1 microm, respectively. Aligned CNTs on the AAO nano template were synthesized by MPECVD at 650 degrees C with the Ni catalyst layer. The length and diameter of CNTs were grown 2 microm and 50 nm, respectively.

  10. Dynamic nanocrystal response and high temperature growth of carbon nanotube-ferroelectric hybrid nanostructure.

    Science.gov (United States)

    Kumar, Ashok; Scott, J F; Katiyar, R S

    2014-01-21

    A long standing problem related to the capping of carbon nanotubes (CNT) by inorganic materials at high temperature has been solved. In situ dynamic response of Pb(Zr0.52Ti0.48)O3 (PZT) nanocrystals attached to the wings of the outer surface of PZT/CNT hybrid-nanostructure has been demonstrated under a constant-energy high-resolution transmission electron microscopy (HRTEM) e-beam. PZT nanocrystals revealed that the crystal orientations, positions, faces, and hopping states change with time. HRTEM study has been performed to investigate the microstructure of hybrid nanostructures and nanosize polycrystal trapped across the wings. Raman spectroscopy was utilized to investigate the local structures, defects, crystal qualities and temperature dependent growth and degradation of hybrid nanostructures. Raman spectra indicate that MWCNT and PZT/MWCNT/n-Si possess good quality of CNT before and after PZT deposition until 650 °C. The monoclinic Cc/Cm phase of PZT which is optimum in piezoelectric properties was prominent in the hybrid structure and should be useful for device applications. An unusual hexagonal faceting oscillation of the nano-crystal perimeter on a 10-30 s period is also observed.

  11. Multifunctional carbon nanotube/bioceramics modulate the directional growth and activity of osteoblastic cells.

    Science.gov (United States)

    Mata, D; Oliveira, F J; Ferro, M; Gomes, P S; Fernandes, M H; Lopes, M A; Silval, R F

    2014-05-01

    Biomaterials can still be reinvented to become simple and universal bone regeneration solutions. Following this roadmap, a bone graft of carbon nanotube (CNT)/glass/hydroxyapatite (HA) with controlled CNT agglomeration state was designed with multifunctionalities able to stimulate the bone cell phenotype. The preparation route, the mechanical and electrical behavior and the in vitro profiles of degradation and osteocompatibility were described. A non-destructive dynamic route was found to have a higher influence than the Diels-Alder functionalization one on controlling the CNT agglomerate state in the ceramic-matrix composite. Biologically safe CNT agglomerates, with diameter sizes below 3 microm homogenously distributed, were obtained in non-functionalized and functionalized composites. Yet, the lowest CNT damage and the highest mechanical and electrical properties were found for the non-functionalized materials. Even though that these composites present higher degradation rate at pH:3 than the ceramic matrix, the CNT agglomerates are released with safe diameter sizes. Also, non-functionalized composites allowed cellular adhesion and modulated the orientation of the cell growth, with a proliferation/differentiation relationship favoring osteoblastic functional activity. Findings offer further contributions for bone tissue engineering by showing that multifunctional bone grafts with high electroconductivity, and integrating CNT agglomerates with maximized interfacing area, allow the in situ control of bone cell functions.

  12. Carbon nanotube junctions and devices

    NARCIS (Netherlands)

    Postma, H.W.Ch.

    2001-01-01

    In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or semiconduct

  13. Vacuum Electron-Beam Evaporation of Fe Nanocrystals on Si3N4 Buffer Layer for carbon Nanotube Growth

    Institute of Scientific and Technical Information of China (English)

    万青; 王太宏; 林成鲁

    2003-01-01

    Vacuum electron-beam evaporated iron nanocrystal is used for the growth of carbon nanotubes. Atomic force microscopy and Raman scattering studies reveal the formation of beta-iron silicide islands on bare silicon substrate after annealing at 700°C in N2 ambient. In order to eliminate the influence of iron-silicon interaction, Si3N4 buffer layer with the thickness of 80 nm is used. This technical route prevents effectively the formation of iron silicide and improves the quality of the iron nanocrystals. Using these iron nanocrystals with high density (about 7 × 1010/cm2) as catalyst, high-density multiwall carbon nanotubes are synthesized on Si3N4/Si substrate.

  14. Growth process and mechanism of a multi-walled carbon nanotube nest deposited on a silicon nanoporous pillar array

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Weifen, E-mail: gingerwfj@yahoo.com.cn [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, No. 36 Beihuan Road, Zhengzhou 450011 (China); Jian Lv; Yang Xiaohui [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, No. 36 Beihuan Road, Zhengzhou 450011 (China); Li Xinjian [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China)

    2010-03-01

    A large scale nest array of multi-walled carbon nanotubes (NACNTs) was grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition. Through observing its macro/micromorphology and structure, ascertaining the catalyst component and its locations at different growth time by hiring field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and selected area electron diffraction, the growth process was deduced. Its thermal properties were also investigated by using a thermogravimetric analyzer. Our experiments demonstrated that the CNTs growth by means of root-growth mechanism at the initial growth stage, then a continuous growth process with its tip open is suggested, finally, a schematic growth model of NACNT/Si-NPA was presented.

  15. Novel growth method of carbon nanotubes using catalyst-support layer developed by alumina grit blasting.

    Science.gov (United States)

    Watanabe, Hiromichi; Ishii, Juntaro; Ota, Keishin

    2016-08-19

    We propose an efficient method of growing carbon nanotube (CNT) arrays on a variety of metals, alloys, and carbon materials using chemical vapor deposition (CVD) assisted by a simple surface treatment of the materials. The main feature of this method is the application of grit blasting with fine alumina particles to the development of a catalyst-support layer required for the growth of CNTs on various conductive materials, including ultra-hard metals such as tungsten. Auger electron spectroscopy shows that grit blasting can form a non-continuous layer where alumina nanoparticles are embedded as residues in the blasting media left on the treated surfaces. This work reveals that such a non-continuous alumina layer can behave as the catalyst-support layer, which is generally prepared by sputter or a vacuum evaporation coating process that considerably restricts the practical applications of CNTs. We have attempted to grow CNTs on grit-blasted substrates of eighteen conventionally used conductive materials using CVD together with a floating iron catalyst. The proposed method was successful in growing multi-walled CNT arrays on the grit-blasted surfaces of all the examined materials, demonstrating its versatility. Furthermore, we found that the group IV metal oxide films thermally grown on the as-received substrates can support the catalytic activity of iron nanoparticles in the CVD process just as well as the alumina film developed by grit blasting. Spectral emissivity of the CNT arrays in the visible and infrared wavelength ranges has been determined to assess the applicability of the CNT arrays as a black coating media.

  16. Novel growth method of carbon nanotubes using catalyst-support layer developed by alumina grit blasting

    Science.gov (United States)

    Watanabe, Hiromichi; Ishii, Juntaro; Ota, Keishin

    2016-08-01

    We propose an efficient method of growing carbon nanotube (CNT) arrays on a variety of metals, alloys, and carbon materials using chemical vapor deposition (CVD) assisted by a simple surface treatment of the materials. The main feature of this method is the application of grit blasting with fine alumina particles to the development of a catalyst-support layer required for the growth of CNTs on various conductive materials, including ultra-hard metals such as tungsten. Auger electron spectroscopy shows that grit blasting can form a non-continuous layer where alumina nanoparticles are embedded as residues in the blasting media left on the treated surfaces. This work reveals that such a non-continuous alumina layer can behave as the catalyst-support layer, which is generally prepared by sputter or a vacuum evaporation coating process that considerably restricts the practical applications of CNTs. We have attempted to grow CNTs on grit-blasted substrates of eighteen conventionally used conductive materials using CVD together with a floating iron catalyst. The proposed method was successful in growing multi-walled CNT arrays on the grit-blasted surfaces of all the examined materials, demonstrating its versatility. Furthermore, we found that the group IV metal oxide films thermally grown on the as-received substrates can support the catalytic activity of iron nanoparticles in the CVD process just as well as the alumina film developed by grit blasting. Spectral emissivity of the CNT arrays in the visible and infrared wavelength ranges has been determined to assess the applicability of the CNT arrays as a black coating media.

  17. Carbon nanotubes for supercapacitor.

    Science.gov (United States)

    Pan, Hui; Li, Jianyi; Feng, Yuanping

    2010-01-05

    As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs) and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage.

  18. Carbon Nanotubes for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Li Jianyi

    2010-01-01

    Full Text Available Abstract As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage.

  19. Effects of a carbon nanotube-collagen coating on a titanium surface on osteoblast growth

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Eun, E-mail: pje312@naver.com; Park, Il-Song, E-mail: ilsong@jbnu.ac.kr; Neupane, Madhav Prasad; Bae, Tae-Sung; Lee, Min-Ho, E-mail: lmh@jbnu.ac.kr

    2014-02-15

    This study was performed to evaluate the effect of collagen-multi-walled carbon nanotubes (MWCNTs) composite coating deposited on titanium on osteoblast growth. Titanium samples coated with only collagen and MWCNTs were used as controls. Pure titanium was coated with collagen-MWCNTs composite coating with 5, 10 and 20 μg cm{sup −2} MWCNTs by dip coating method. Scanning probe microscopy, field emission scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy were used to ascertain the root mean squared roughness, structural and morphological features and, the interaction between the collagen and the MWCNTs, respectively. The biocompatibility of the collagen-MWCNTs composite coated Ti was assessed by MTT and ALP activity assays after culturing the cells for 2 and 5 days. The study reveals that root mean squared surface roughness of collagen-MWCNTs composite coated titanium is relatively higher than those of collagen and MWCNTs coated Ti. There is a strong interaction between the MWCNTs and the collagen, which is supported by the inferences made in FE-SEM and TEM studies and further confirmed by FT-IR spectra. Among all the specimens tested, cell proliferation is relatively higher on collagen-MWCNTs composite coated Ti specimen incorporated with 20 μg cm{sup −2} of MWCNTs (p < 0.05) after 5 days of cell culture. Cell proliferation studies confirm the existence of a strong dependence of the extent of cell proliferation on the amount of MWCNTs incorporated in the composite; the higher the amount of MWCNTs, the greater the extent of cell proliferation. The higher surface roughness of collagen-MWCNTs composite coated Ti specimens is considered responsible for the relatively higher extent of cell proliferation. The MWCNTs incorporated in the composite could have also contributed to the cell viability and growth.

  20. Low Temperature Growth of Vertically Aligned Carbon Nanotubes via Floating Catalyst Chemical Vapor Deposition Method

    Institute of Scientific and Technical Information of China (English)

    M.R. Atiyan; D.R. Awang Biak; F. Ahmadun; I.S. Ahamad; F. Mohd Yasin; H. Mohamed Yusoff

    2011-01-01

    Synthesis of carbon nanotubes (CNTs) below 600℃ using supporting catalyst chemical vapor deposition method was reported by many research groups. However, the floating catalyst chemical vapor deposition received less attention due to imperfect nanotubes produced. In this work, the effects of varying the preheating temperature on the synthesis of CNT were investigated. The reaction temperature was set at 570℃. The preheating set temperature was varied from 150 to 400℃ at 50℃ interval. Three O-ring shape heating mantels were used as heating source for the preheater. In situ monitoring device was used to observe the temperature profile in the reactor. Benzene and ferrocene were used as the carbon source and catalyst precursor, respectively. Vertically aligned CNTs were synthesized when the preheating temperature was set at 400℃. When the preheating temperature was increased up to 400℃, both the length and the alignment of CNTs produced were improved.

  1. Growth of Aligned Carbon Nanotubes through Microwave Plasma Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    王升高; 汪建华; 马志斌; 王传新; 满卫东

    2005-01-01

    Aligned carbon nanotubes (CNTs) were synthesized on glass by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at the low temperature of 550 ℃. The experimental results show that both the self-bias potential and the density of the catalyst particles are responsible for the alignment of CNTs. When the catalyst particle density is high enough, strong interactions among the CNTs can inhibit CNTs from growing randomly and result in parallel alignment.

  2. Growth of metal-catalyst-free nitrogen-doped metallic single-wall carbon nanotubes

    Science.gov (United States)

    Li, Jin-Cheng; Hou, Peng-Xiang; Zhang, Lili; Liu, Chang; Cheng, Hui-Ming

    2014-09-01

    Nitrogen-doped (N-doped) single-wall carbon nanotubes (SWCNTs) were synthesized by chemical vapor deposition using SiOx nanoparticles as a catalyst and ethylenediamine as the source of both carbon and nitrogen. The N-doped SWCNTs have a mean diameter of 1.1 nm and a narrow diameter range, with 92% of them having diameters from 0.7 to 1.4 nm. Multi-wavelength laser Raman spectra and temperature-dependent electrical resistance indicate that the SWCNT sample is enriched with metallic nanotubes. These N-doped SWCNTs showed excellent electrocatalytic activity for the oxygen reduction reaction and highly selective and sensitive sensing ability for dopamine detection.Nitrogen-doped (N-doped) single-wall carbon nanotubes (SWCNTs) were synthesized by chemical vapor deposition using SiOx nanoparticles as a catalyst and ethylenediamine as the source of both carbon and nitrogen. The N-doped SWCNTs have a mean diameter of 1.1 nm and a narrow diameter range, with 92% of them having diameters from 0.7 to 1.4 nm. Multi-wavelength laser Raman spectra and temperature-dependent electrical resistance indicate that the SWCNT sample is enriched with metallic nanotubes. These N-doped SWCNTs showed excellent electrocatalytic activity for the oxygen reduction reaction and highly selective and sensitive sensing ability for dopamine detection. Electronic supplementary information (ESI) available: Additional information including Raman spectra, ORR polarization curves, CV curves, etc. See DOI: 10.1039/c4nr03172e

  3. INTERACTION-MEDIATED GROWTH OF CARBON NANOTUBES ON ACICULAR SILICA-COATED α-Fe CATALYST BY CHEMICAL VAPOR DEPOSITION

    Institute of Scientific and Technical Information of China (English)

    Qixiang Wang; Guoqing Ning; Fei Wei; Guohua Luo

    2003-01-01

    Multi-walled carbon nanotubes (MWNTs) with 20 nm outer diameter were prepared by chemical vapor deposition of ethylene using ultrafine surface-modified acicular α-Fe catalyst particles. The growth mechanism of MWNTs on the larger catalyst particles are attributed to the interaction between the Fe nanoparticles with the surface-modified silica layer. This interaction-mediated growth mechanism is illustrated by studying the electronic, atomic and crystal properties of surface-modified catalysts and MWNTs products by characterization with X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA) and Raman spectra.

  4. A Comparative Study of Three Different Chemical Vapor Deposition Techniques of Carbon Nanotube Growth on Diamond Films

    Science.gov (United States)

    2013-01-01

    1187–1194, 2010. [28] L. T. Sun, J. L. Gong , Z. Y. Zhu et al., “Nanocrystalline diamond from carbon nanotubes,” Applied Physics Letters, vol. 84, no. 15...pp. 759–760, 1994. [33] G. Zhang, P. Qi , X. Wang et al., “Hydrogenation and hydro- carbonation and etching of single-walled carbon nanotubes,” Journal

  5. Growth of carbon nanotubes and microfibers over stainless steel mesh by cracking of methane

    OpenAIRE

    2008-01-01

    The ${La}_{2}{NiO}_{4}$ film was synthesized on the 304 stainless steel (SS) mesh. The hydrogen reduction of La2NiO4 generated homogeneous nanocatalyst particles (probably ${Ni}/{La}_2{O}_{3}$) over which methane was cracked, producing carbon notubes/microfibers and hydrogen. The carbon nanotubes/microfibers were strongly bonded to the SS mesh. It was observed that the methane conversion always reached its maximum at the cracking temperature of 750 °C regardless of its concentration varying f...

  6. Carbon Nanotube Purification

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Delzeit, Clement J. (Inventor)

    2005-01-01

    A method for cleaning or otherwise removing amorphous carbon and other residues that arise in growth of a carbon nanotube (CNT) array. The CNT array is exposed to a plurality of hydroxyls or hydrogen, produced from a selected vapor or liquid source such as H2O or H2O2. and the hydroxyls or hydrogen (neutral or electrically charged) react with the residues to produce partly or fully dissolved or hydrogenated or hydroxylizated products that can be removed or separated from the CNT array. The hydroxyls or hydrogen can be produced by heating the CNT array, residue and selected vapor or liquid source or by application of an electromagnetic excitation signal with a selected frequency or range of frequencies to dissociate the selected vapor or liquid. The excitation frequency can be chirped to cover a selected range of frequencies corresponding to dissociation of the selected vapor or liquid. Sonication may be uscd to supplement dissociation of the H2O and/or H2O2.

  7. Growth Mechanism of a Hybrid Structure Consisting of a Graphite Layer on Top of Vertical Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Nicolo' Chiodarelli

    2012-01-01

    Full Text Available Graphene and carbon nanotubes (CNTs are both carbon-based materials with remarkable optical and electronic properties which, among others, may find applications as transparent electrodes or as interconnects in microchips, respectively. This work reports on the formation of a hybrid structure composed of a graphitic carbon layer on top of vertical CNT in a single deposition process. The mechanism of deposition is explained according to the thickness of catalyst used and the atypical growth conditions. Key factors dictating the hybrid growth are the film thickness and the time dynamic through which the catalyst film dewets and transforms into nanoparticles. The results support the similarities between chemical vapor deposition processes for graphene, graphite, and CNT.

  8. Carbon nanotubes in tissue engineering.

    Science.gov (United States)

    Bosi, Susanna; Ballerini, Laura; Prato, Maurizio

    2014-01-01

    As a result of their peculiar features, carbon nanotubes (CNTs) are emerging in many areas of nanotechnology applications. CNT-based technology has been increasingly proposed for biomedical applications, to develop biomolecule nanocarriers, bionanosensors and smart material for tissue engineering purposes. In the following chapter this latter application will be explored, describing why CNTs can be considered an ideal material able to support and boost the growth and the proliferation of many kinds of tissues.

  9. Direct growth of carbon nanotubes on metal surfaces without an external catalyst and nanocomposite production

    Science.gov (United States)

    Baddour, Carole Emilie

    The research work presented in this thesis deals with carbon nanotubes (CNTs), an allotrope of carbon with a cylindrical structure consisting of a rolled up graphene sheet. CNTs are generally produced by the decomposition of a carbon source in the presence of a metal catalyst at elevated temperatures. CNTs have outstanding properties and have attracted immense attention in both industry and academia. However, the development of commercial applications of CNTs is slow due to limitations in the large scale production of CNTs and their high cost. Another limitation is the interface resistance generated by external catalyst nanoparticles used in traditional CNT growth methods. In order to eliminate the interface resistance and simultaneously provide CNT growth over large surfaces and varying geometries, a method called direct CNT growth is established to enable the extraction of the CNT structure directly from the metal surface. The novel process for the production of CNTs developed in the present thesis is applied to planar surfaces and spherical particles made of stainless steel (SS) 304. The method is based on the establishment of nanometer scale structures at the surface which act as catalyst nanoparticles while at the same time being integral parts of the material. It uses first a mild chemical etching of the surface, followed by a specific heat treatment performed using either standard chemical vapour deposition (standard-CVD) or fluidized bed CVD (FBCVD) techniques. Acetylene (C2H2) is used as the carbon source and SS 304 acts as both the catalyst and the substrate in the growth process. This direct CNT growth with this substrate dual function eliminates the need of external catalyst nanoparticles deposited onto the surface. The active sites necessary for CNT growth are tailored on the SS itself by means of the two-step treatment process. MWNTs of 20-70 nm in diameter are produced. The CNTs are characterized by Raman Spectroscopy, Thermogravimetric analysis (TGA

  10. Influence of Mo on the Fe:Mo:C nanocatalyst thermodynamics for single-walled carbon nanotube growth

    Science.gov (United States)

    Curtarolo, Stefano; Awasthi, Neha; Setyawan, Wahyu; Jiang, Aiqin; Bolton, Kim; Tokune, Toshio; Harutyunyan, Avetik R.

    2008-08-01

    We explore the role of Mo in Fe:Mo nanocatalyst thermodynamics for low-temperature chemical-vapor deposition growth of single-walled carbon nanotubes (SWCNTs). By using the size-pressure approximation and ab initio modeling, we prove that for both Fe-rich ( ˜80% Fe or more) and Mo-rich ( ˜50% Mo or more) Fe:Mo clusters, the presence of carbon in the cluster causes nucleation of Mo2C . This enhances the activity of the particle since it releases Fe, which is initially bound in a stable Fe:Mo phase, so that it can catalyze SWCNT growth. Furthermore, the presence of small concentrations of Mo reduces the lower size limit of low-temperature steady-state growth from ˜0.58nm for pure Fe particles to ˜0.52nm . Our ab initio-thermodynamic modeling explains experimental results and establishes a direction to search for better catalysts.

  11. Fe-Ti-O based catalyst for large-chiral-angle single-walled carbon nanotube growth

    DEFF Research Database (Denmark)

    He, Maoshuai; Zhang, Lili; Jiang, Hua

    2016-01-01

    Catalyst selection is very crucial for controlled growth of single-walled carbon nanotubes (SWNTs). Here we introduce a well-designed Fe-Ti-O solid solution for SWNT growth with a high preference to large chiral angles. The Fe-Ti-O catalyst was prepared by combining Ti layer deposition onto premade...... Fe nanoparticles with subsequent high-temperature air calcination, which favours the formation of a homogeneous Fe-Ti-O solid solution. Using CO as the carbon feedstock, chemical vapour deposition growth of SWNTs at 800 °C was demonstrated on the Fe-Ti-O catalyst. Nanobeam electron diffraction...... characterization on a number of individual SWNTs revealed that more than 94% of SWNTs have chiral angles larger than 15°. In situ environmental transmission electron microscopy study was carried out to reveal the catalyst dynamics upon reduction. Our results identify that the phase segregation through reducing Fe...

  12. Carbon nanotube filters

    Science.gov (United States)

    Srivastava, A.; Srivastava, O. N.; Talapatra, S.; Vajtai, R.; Ajayan, P. M.

    2004-09-01

    Over the past decade of nanotube research, a variety of organized nanotube architectures have been fabricated using chemical vapour deposition. The idea of using nanotube structures in separation technology has been proposed, but building macroscopic structures that have controlled geometric shapes, density and dimensions for specific applications still remains a challenge. Here we report the fabrication of freestanding monolithic uniform macroscopic hollow cylinders having radially aligned carbon nanotube walls, with diameters and lengths up to several centimetres. These cylindrical membranes are used as filters to demonstrate their utility in two important settings: the elimination of multiple components of heavy hydrocarbons from petroleum-a crucial step in post-distillation of crude oil-with a single-step filtering process, and the filtration of bacterial contaminants such as Escherichia coli or the nanometre-sized poliovirus (~25 nm) from water. These macro filters can be cleaned for repeated filtration through ultrasonication and autoclaving. The exceptional thermal and mechanical stability of nanotubes, and the high surface area, ease and cost-effective fabrication of the nanotube membranes may allow them to compete with ceramic- and polymer-based separation membranes used commercially.

  13. Carbon nanotubes for microelectronics?

    Science.gov (United States)

    Graham, Andrew P; Duesberg, Georg S; Seidel, Robert V; Liebau, Maik; Unger, Eugen; Pamler, Werner; Kreupl, Franz; Hoenlein, Wolfgang

    2005-04-01

    Despite all prophecies of its end, silicon-based microelectronics still follows Moore's Law and continues to develop rapidly. However, the inherent physical limits will eventually be reached. Carbon nanotubes offer the potential for further miniaturization as long as it is possible to selectively deposit them with defined properties.

  14. Nitrogen doping in carbon nanotubes.

    Science.gov (United States)

    Ewels, C P; Glerup, M

    2005-09-01

    Nitrogen doping of single and multi-walled carbon nanotubes is of great interest both fundamentally, to explore the effect of dopants on quasi-1D electrical conductors, and for applications such as field emission tips, lithium storage, composites and nanoelectronic devices. We present an extensive review of the current state of the art in nitrogen doping of carbon nanotubes, including synthesis techniques, and comparison with nitrogen doped carbon thin films and azofullerenes. Nitrogen doping significantly alters nanotube morphology, leading to compartmentalised 'bamboo' nanotube structures. We review spectroscopic studies of nitrogen dopants using techniques such as X-ray photoemission spectroscopy, electron energy loss spectroscopy and Raman studies, and associated theoretical models. We discuss the role of nanotube curvature and chirality (notably whether the nanotubes are metallic or semiconducting), and the effect of doping on nanotube surface chemistry. Finally we review the effect of nitrogen on the transport properties of carbon nanotubes, notably its ability to induce negative differential resistance in semiconducting tubes.

  15. The Toxicology of Carbon Nanotubes

    Science.gov (United States)

    Donaldson, Ken; Poland, Craig; Duffin, Rodger; Bonner, James

    2012-06-01

    1. Carbon nanotube structure, synthesis and applications C. Singh and W. Song; 2. The aerodynamic behaviour and pulmonary deposition of carbon nanotubes A. Buckley, R. Smith and R Maynard; 3. Utilising the concept of the biologically effective dose to define the particle and fibre hazards of carbon nanotubes K. Donaldson, R. Duffin, F. Murphy and C. Poland; 4. CNT, biopersistence and the fibre paradigm D. Warheit and M. DeLorme; 5. Length-dependent retention of fibres in the pleural space C. Poland, F. Murphy and K. Donaldson; 6. Experimental carcinogenicity of carbon nanotubes in the context of other fibres K. Unfried; 7. Fate and effects of carbon nanotubes following inhalation J. Ryman-Rasmussen, M. Andersen and J. Bonner; 8. Responses to pulmonary exposure to carbon nanotubes V. Castranova and R. Mercer; 9. Genotoxicity of carbon nanotubes R. Schins, C. Albrecht, K. Gerloff and D. van Berlo; 10. Carbon nanotube-cellular interactions; macrophages, epithelial and mesothelial cells V. Stone, M. Boyles, A. Kermanizadeh, J. Varet and H. Johnston; 11. Systemic health effects of carbon nanotubes following inhalation J. McDonald; 12. Dosimetry and metrology of carbon nanotubes L. Tran, L. MacCalman and R. Aitken; Index.

  16. Laser-assisted growth of carbon nanotubes on laser-patterned substrates and inside sealed micro-channels

    NARCIS (Netherlands)

    Burgt, Y. van de; Bellouard, Y.

    2014-01-01

    Carbon nanotube assemblies can be used for specific applications such as sensors and filters. We present a method and proof-of-concept to directly grow vertically-aligned carbon nanotube structures within sealed enclosures by means of a feedback-controlled laser-assisted chemical vapor deposition te

  17. Post-CMOS wafer level growth of carbon nanotubes for low-cost microsensors-a proof of concept

    Energy Technology Data Exchange (ETDEWEB)

    Santra, Sumita; Guha, Prasanta K; Zhong, Guofang; Robertson, John; Milne, William I; Udrea, Florin [Engineering Department, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Ali, Syed Z [Cambridge CMOS Sensors Ltd, Wellington House, East Road, Cambridge CB1 1BH (United Kingdom); Covington, James A; Gardner, Julian W, E-mail: ss778@cam.ac.uk [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2010-12-03

    Here we demonstrate a novel technique to grow carbon nanotubes (CNTs) on addressable localized areas, at wafer level, on a fully processed CMOS substrate. The CNTs were grown using tungsten micro-heaters (local growth technique) at elevated temperature on wafer scale by connecting adjacent micro-heaters through metal tracks in the scribe lane. The electrical and optical characterization show that the CNTs are identical and reproducible. We believe this wafer level integration of CNTs with CMOS circuitry enables the low-cost mass production of CNT sensors, such as chemical sensors.

  18. Growth and structural discrimination of cortical neurons on randomly oriented and vertically aligned dense carbon nanotube networks

    Directory of Open Access Journals (Sweden)

    Christoph Nick

    2014-09-01

    Full Text Available The growth of cortical neurons on three dimensional structures of spatially defined (structured randomly oriented, as well as on vertically aligned, carbon nanotubes (CNT is studied. Cortical neurons are attracted towards both types of CNT nano-architectures. For both, neurons form clusters in close vicinity to the CNT structures whereupon the randomly oriented CNTs are more closely colonised than the CNT pillars. Neurons develop communication paths via neurites on both nanoarchitectures. These neuron cells attach preferentially on the CNT sidewalls of the vertically aligned CNT architecture instead than onto the tips of the individual CNT pillars.

  19. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    Science.gov (United States)

    Yang, Jun; Yao, Zhiwen; Tang, Changyu; Darvell, B. W.; Zhang, Hualin; Pan, Lingzhan; Liu, Jingsong; Chen, Zhiqing

    2009-07-01

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  20. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun; Yao Zhiwen [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Tang Changyu [Department of Polymer Science and Materials, Sichuan University (China); Darvell, B.W. [Dental Materials Science, Faculty of Dentistry, University of Hong Kong (Hong Kong); Zhang Hualin; Pan Lingzhan; Liu Jingsong [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Chen Zhiqing, E-mail: yangj0710@gmail.com [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China)

    2009-07-30

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  1. Iron-carbide cluster thermal dynamics for catalyzed carbon nanotube growth

    Science.gov (United States)

    Ding, Feng; Bolton, Kim; Rosén, Arne

    2004-07-01

    Molecular dynamics simulations have been used to study the thermal behavior of FeN-mCm clusters where N, the total number of atoms, extends up to 2400. Comparison of the computed results with experimental data shows that the simulations yield the correct trends for the liquid-solid region of the iron-carbide phase diagram as well as the correct dependence of cluster melting point as a function of cluster size. The calculation indicates that, when carbon nanotubes (CNTs) are grown on large (>3-4 nm) catalyst particles at low temperatures (melting of the cluster. .

  2. Local Synthesis of Carbon Nanotubes in Silicon Microsystems: The Effect of Temperature Distribution on Growth Structure

    Directory of Open Access Journals (Sweden)

    Knut E. Aasmundtveit

    2013-07-01

    Full Text Available Local synthesis and direct integration of carbon nanotubes (CNTs into microsystems is a promising method for producing CNT-based devices in a single step, low-cost, and wafer-level, CMOS/MEMS-compatible process. In this report, the structure of the locally grown CNTs are studied by transmission imaging in scanning electron microscopy—S(TEM. The characterization is performed directly on the microsystem, without any post-synthesis processing required. The results show an effect of temperature on the structure of CNTs: high temperature favors thin and regular structures, whereas low temperature favors “bamboo-like” structures.

  3. Carbon Nanotube Purification and Functionalization

    Science.gov (United States)

    Lebron, Marisabel; Mintz, Eric; Smalley, Richard E.; Meador, Michael A.

    2003-01-01

    Carbon nanotubes have the potential to significantly enhance the mechanical, thermal, and electrical properties of polymers. However, dispersion of carbon nanotubes in a polymer matrix is hindered by the electrostatic forces that cause them to agglomerate. Chemical modification of the nanotubes is necessary to minimize these electrostatic forces and promote adhesion between the nanotubes and the polymer matrix. In a collaborative research program between Clark Atlanta University, Rice University, and NASA Glenn Research Center several approaches are being explored to chemically modify carbon nanotubes. The results of this research will be presented.

  4. Production of carbon nanotubes

    Science.gov (United States)

    Journet, C.; Bernier, P.

    Carbon nanostructures such as single-walled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods. Most of them are based on the sublimation of carbon under an inert atmosphere, such as the electric arc discharge process, the laser ablation method, or the solar technique. But chemical methods can also be used to synthesize these kinds of carbon materials: the catalytic decomposition of hydrocarbons, the production by electrolysis, the heat treatment of a polymer, the low temperature solid pyrolysis, or the in situ catalysis.

  5. Catalytic growth of single-, double-, and multi-walled carbon nanotubes and studies of their potential applications

    Science.gov (United States)

    Kayastha, Vijaya Kumar

    Catalytic growth of carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD) was investigated, and role of various growth parameters on the CNT growth rate, density and structures was identified. A unified growth model was proposed which involves dissociative adsorption of acetylene on catalyst particles, and vapor-liquid-solid mechanism. According to it, balance between decomposition of C2H2 molecules on the catalyst surface, and diffusion of released carbon atoms into the catalyst particles is the key step towards the continuous growth of CNTs. Guided by our growth model, we demonstrated the growth of ultra-high dense vertically aligned multi-walled as well as rarely reported vertically aligned single-walled and double-walled CNTs. Post-growth manipulation and purification of CNTs by using AC electric field (dielectrophoresis) were investigated. Deeper understanding on the roles of the applied field strength and AC frequency was achieved. Increasing the electric field enhances the density of aligned nanotubes while increasing frequency enhances the dispersion, and hence the degree of alignment of CNTs, but reduces the nanotube density. CNTs were placed across a pair of electrodes with control of density and degree of alignment. Individual CNTs were successfully placed on an AFM tip. We investigated electron field emission from various types of CNT films and found that graphitic order of the CNTs is a major intrinsic factor which affects the emission current stability. Due to superior structural order, MWCNTs grown by thermal CVD have better emission stability than those grown by plasma enhanced CVD. These findings were explained by introducing a concept of emission current-induced dislocation and electron trapping effects, in which the dislocations induced in CNTs, and thus the electron transport along the CNTs prior to electron tunneling through them depend on the graphitic order of the CNTs. MWCNTs were successfully integrated into 2D and 3D carbon

  6. The role of catalytic nanoparticle pretreatment on the growth of vertically aligned carbon nanotubes by hot-filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Hwan; Gohier, Aurélien; Bourée, Jean Eric; Châtelet, Marc; Cojocaru, Costel-Sorin, E-mail: costel-sorin.cojocaru@polytechnique.edu

    2015-01-30

    The effect of atomic hydrogen assisted pre-treatment on the growth of vertically aligned carbon nanotubes using hot-filament chemical vapor deposition was investigated. Iron nanoparticle catalysts were formed on an aluminum oxide support layer by spraying of iron chloride salt solutions as catalyst precursor. It is found that pre-treatment time and process temperature tune the density as well as the shape and the structure of the grown carbon nanotubes. An optimum pre-treatment time can be found for the growth of long and well aligned carbon nanotubes, densely packed to each other. To provide insight on this behavior, the iron catalytic nanoparticles formed after the atomic hydrogen assisted pre-treatment were analyzed by atomic force microscopy. The relations between the size and the density of the as-formed catalyst and the as-grown carbon nanotube's structure and density are discussed. - Highlights: • Effect of the atomic hydrogen assisted pre-treatment on the growth of VACNT using hot-filament CVD. • Pre-treatment time and process temperature tune the density, the shape and the structure of the CNTs. • Correlations between size and density of the as-formed catalyst and the CNT’s structure and density. • Carbon nanotubes synthesized at low temperature down to 500 °C using spayed iron chloride salts. • Density of the CNT carpet adjusted by catalytic nanoparticle engineering.

  7. Carbon nanotube network varactor

    Science.gov (United States)

    Generalov, A. A.; Anoshkin, I. V.; Erdmanis, M.; Lioubtchenko, D. V.; Ovchinnikov, V.; Nasibulin, A. G.; Räisänen, A. V.

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

  8. Carbon Nanotube Thermoelectric Coolers

    Science.gov (United States)

    2015-02-06

    conductance. Inside thecentral section of the carbon nanotube, we obtained an impressive Peltier cooling 57 K down from the liquid nitrogentemperature. 15... trapped charges or dipoles) that occur either at the interface between the CNT and the gate dielectric (interface defects) or at some position within... liquid nitrogen temperature 77T  K up to hot 134 8T  K, or decreases from 77T  K down to about cold 20 6T  K, thus evidencing a strong

  9. Carbon nanotube biosensors

    OpenAIRE

    Tîlmaciu, Carmen-Mihaela; Morris, May C

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we pr...

  10. Carbon Nanotubes Based Quantum Devices

    Science.gov (United States)

    Lu, Jian-Ping

    1999-01-01

    This document represents the final report for the NASA cooperative agreement which studied the application of carbon nanotubes. The accomplishments are reviewed: (1) Wrote a review article on carbon nanotubes and its potentials for applications in nanoscale quantum devices. (2) Extensive studies on the effects of structure deformation on nanotube electronic structure and energy band gaps. (3) Calculated the vibrational spectrum of nanotube rope and the effect of pressure. and (4) Investigate the properties of Li intercalated nanotube ropes and explore their potential for energy storage materials and battery applications. These studies have lead to four publications and seven abstracts in international conferences.

  11. Optimal deposition conditions of TiN barrier layers for the growth of vertically aligned carbon nanotubes onto metallic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Cespedes, J; Bertran, E [FEMAN Group, IN2UB, Departament de Fisica Aplicada i Optica, Universitat de Barcelona, C/ Martii Franques, 1, E-08028, Barcelona (Spain); Alvarez-Garcia, J [Centre de Recerca i Investigacio de Catalunya, S.A., Travessera de Gracia 108, Entressol, E-08012, Barcelona (Spain); Zhang, X; Hampshire, J [Teer Coatings Ltd, West Stone House, Berry Hill Industrial Estate, Droitwich, Worcestershire, WR9 9AS (United Kingdom)

    2009-05-21

    Plasma enhanced chemical deposition (PECVD) has proven over the years to be the preferred method for the growth of vertically aligned carbon nanotubes and nanofibres (VACNTs and VACNFs, respectively). In particular, carbon nanotubes (CNTs) grown on metallic surfaces present a great potential for high power applications, including low resistance electrical contacts, high power switches, electron guns or supercapacitors. Nevertheless, the deposition of CNTs onto metallic substrates is challenging, due to the intrinsic incompatibility between such substrates and the metallic precursor layers required to promote the growth of CNTs. In particular, the formation of CNT films is assisted by the presence of a nanometric (10-100 nm) monolayer of catalyst clusters, which act as nucleation sites for CNTs. The nanometric character of the precursor layer, together with the high growth temperature involved during the PECVD process ({approx}700 deg. C), strongly favours the in-diffusion of the catalyst nanoclusters into the bulk of the metallic substrate, which results in a dramatic reduction in the nucleation of CNTs. In order to overcome this problem, it is necessary to coat the metallic substrate with a diffusion barrier layer, prior to the growth of the catalyst precursor. Unlike other conventional ceramic barrier layers, TiN provides high electrical conductivity, thus being a promising candidate for use as barrier material in applications involving low resistance contacts. In this work we investigate the anti-diffusion properties of TiN sputtered coatings and its potential applicability to the growth of CNTs onto copper substrates, using Fe as catalyst material. The barrier and catalyst layers were deposited by magnetron sputtering. Auger electron spectroscopy was used to determine the diffusivity of Fe into TiN. Morphological characterization of the CNTs coatings was performed on scanning and transmission electron microscopes. Raman spectroscopy and x-ray diffraction were

  12. Growth of Ag nanoparticles using plasma-modified multi-walled carbon nanotubes.

    Science.gov (United States)

    Tseng, Chun-Hao; Chen, Chuh-Yung

    2008-01-23

    This study presents a novel method for preparing multi-walled carbon nanotubes (MWNTs) grafted with a poly(2-hydroxyethyl methacrylate) (HEMA)-silver complex (CNTs-HEMA-Ag complex) through plasma-induced grafting polymerization. The characteristics of the MWNTs after being grafted with HEMA polymer are monitored by Fourier transform infrared (FT-IR) spectroscopy. The chelating groups in the HEMA polymer grafted on the surface of the CNTs-HEMA are the coordination sites for chelating silver ions, and are further used as nanotemplates for the growing of Ag nanoparticles (quantum dots). Transmission electron microscopy (TEM) reveals that the particle size of Ag nanoparticles on the CNT surfaces increases with the Ag(+) chelating concentration, reaction time, and reaction temperature. Moreover, the crystalline phase of Ag nanoparticles is identified by using x-ray diffraction (XRD). In addition, high-resolution x-ray photoelectron spectroscopy (XPS) is used to characterize the functional groups on the surface of the MWNTs after chemical modification through plasma treatment; it demonstrates that the growing amount of the Ag nanoparticles on the nanotubes increases with the Ag(+) chelating concentration due to the blocking effect of the Ag particles forming on the MWNTs.

  13. Selective and uniform growth of single-wall carbon nanotubes (SWCNTs) for gas sensing application

    Science.gov (United States)

    Alvi, M. A.; Al-Ghamdi, A. A.; Khan, Shamshad A.

    2017-03-01

    In the present work, we have synthesized uniformly distributed single-wall carbon nanotube (SWCNT) networks with a selective diameter suitable for gas sensing device. The SWCNT networks have been synthesized on 2-nm-thick iron (Fe) catalyst-coated silicon (Si) substrates by Plasma-Enhanced Chemical Vapor Deposition (PECVD). The as-grown SWCNTs were characterized by field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy techniques. Using SWCNT network, the sensitivity of ammonia (NH3) gases/vapors was recognized by their surface adsorption and desorption responses. The response curve was observed from the SWCNT network, which is due to a change in the resistance upon exposure to NH3 gas.

  14. Growth of single wall carbon nanotubes using PECVD technique: An efficient chemiresistor gas sensor

    Science.gov (United States)

    Lone, Mohd Yaseen; Kumar, Avshish; Husain, Samina; Zulfequar, M.; Harsh; Husain, Mushahid

    2017-03-01

    In this work, the uniform and vertically aligned single wall carbon nanotubes (SWCNTs) have been grown on Iron (Fe) deposited Silicon (Si) substrate by plasma enhanced chemical vapor deposition (PECVD) technique at very low temperature of 550 °C. The as-grown samples of SWCNTS were characterized by field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM) and Raman spectrometer. SWCNT based chemiresistor gas sensing device was fabricated by making the proper gold contacts on the as-grown SWCNTs. The electrical conductance and sensor response of grown SWCNTs have been investigated. The fabricated SWCNT sensor was exposed to ammonia (NH3) gas at 200 ppm in a self assembled apparatus. The sensor response was measured at room temperature which was discussed in terms of adsorption of NH3 gas molecules on the surface of SWCNTs. The achieved results are used to develope a miniaturized gas sensor device for monitoring and control of environment pollutants.

  15. Growth of linear Ni-filled carbon nanotubes by local arc discharge in liquid ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Sagara, Takuya [Department of Electric Engineering, Graduated School of Science and Technology, Nihon University, 1-8-14 Surugadai Kanda, Chiyoda, Tokyo 101-8308 (Japan); Kurumi, Satoshi [Department of Electric Engineering, College of Science and Technology, Nihon University, 1-8-14 Surugadai Kanda, Chiyoda, Tokyo 101-8308 (Japan); Suzuki, Kaoru, E-mail: kaoru@ele.cst.nihon-u.ac.jp [Department of Electric Engineering, College of Science and Technology, Nihon University, 1-8-14 Surugadai Kanda, Chiyoda, Tokyo 101-8308 (Japan)

    2014-02-15

    The cylindrical geometry of carbon nanotubes (CNTs) allows them to be filled with metal catalysts; the resulting metal-filled CNTs possess different properties depending on the filler metal. Here we report the synthesis of Ni-filled CNTs in which Ni is situated linearly and homogeneously by local arc discharge in liquid ethanol. The structural characteristics of synthesized Ni-filled CNTs were determined by transmission electron microscopy (TEM), and the relationship between pyrolysis conditions and the length and diameter of Ni-filled CNTs was examined. The encapsulated Ni was identified by a TEM-equipped energy-dispersive X-ray spectroscope and found to have a single-crystal fcc structure by nano-beam diffraction. The features of linear Ni-filled CNT are expected to be applicable to probes for magnetic force microscopy.

  16. Highly efficient growth of vertically aligned carbon nanotubes on Fe-Ni based metal alloy foils for supercapacitors

    Science.gov (United States)

    Amalina Raja Seman, Raja Noor; Asyadi Azam, Mohd; Ambri Mohamed, Mohd

    2016-12-01

    Supercapacitors are highly promising energy devices with superior charge storage performance and a long lifecycle. Construction of the supercapacitor cell, especially electrode fabrication, is critical to ensure good performance in applications. This work demonstrates direct growth of vertically aligned carbon nanotubes (CNTs) on Fe-Ni based metal alloy foils, namely SUS 310S, Inconel 600 and YEF 50, and their use in symmetric vertically aligned CNT supercapacitor electrodes. Alumina and cobalt thin film catalysts were deposited onto the foils, and then CNT growth was performed using alcohol catalytic chemical vapour deposition. By this method, vertically aligned CNTs were successfully grown and used directly as a binder-free supercapacitor electrode to deliver excellent electrochemical performance. The device showed relatively good specific capacitance, a superior rate capability and excellent cycle stability, maintaining about 96% capacitance up to 1000 cycles.

  17. Lithium interaction with carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Nalimova, V.A. [Moskovskij Gosudarstvennyj Univ., Moscow (Russian Federation). Khimicheskij Fakul`tet; Sklovsky, D.E. [Moskovskij Gosudarstvennyj Univ., Moscow (Russian Federation). Khimicheskij Fakul`tet; Bondarenko, G.N. [Topcheiv Institute of Petrochemical Synthesis, Leninsky Prospekt, 29, Moscow (Russian Federation); Alvergnat-Gaucher, H. [CRMD, CNRS, Universite d`Orleans, 1B rue de la Ferollerie, 45071, Orleans Cedex 02 (France); Bonnamy, S. [CRMD, CNRS, Universite d`Orleans, 1B rue de la Ferollerie, 45071, Orleans Cedex 02 (France); Beguin, F. [CRMD, CNRS, Universite d`Orleans, 1B rue de la Ferollerie, 45071, Orleans Cedex 02 (France)

    1997-05-01

    Lithium interaction with catalytic carbon nanotubes under high-pressure conditions was studied. A large amount of Li (2Li/C) reacted with the carbon nanotubes forming an intercalation compound (I{sub c}{proportional_to}4.1 A) which follows from X-ray diffraction and IR spectroscopy data. We cannot exclude also the possibility of insertion of a part of Li into the channel of the nanotubes. (orig.)

  18. Carbon nanotube Archimedes screws.

    Science.gov (United States)

    Oroszlány, László; Zólyomi, Viktor; Lambert, Colin J

    2010-12-28

    Recently, nanomechanical devices composed of a long stationary inner carbon nanotube and a shorter, slowly rotating outer tube have been fabricated. In this paper, we study the possibility of using such devices as nanoscale transducers of motion into electricity. When the outer tube is chiral, we show that such devices act like quantum Archimedes screws, which utilize mechanical energy to pump electrons between reservoirs. We calculate the pumped charge from one end of the inner tube to the other, driven by the rotation of a chiral outer nanotube. We show that the pumped charge can be greater than one electron per 360° rotation, and consequently, such a device operating with a rotational frequency of 10 MHz, for example, would deliver a current of ≈1 pAmp.

  19. Carbon Nanotube Growth Rate Regression using Support Vector Machines and Artificial Neural Networks

    Science.gov (United States)

    2014-03-27

    rates are realized by this faster search. 1.3 Assumptions The machine learning approach used for extracting optimal growth parameters assumes the catalyst...and high strength polymers. [25] All carbon to carbon bonds are filled in a CNT so they are chemically inert and stable in acids, bases and solvents ...research in maximizing CNT length. SWNTs of 18.5 cm in length were obtained by using an ethanol precursor and an iron molybdenum catalyst [10]. Also, by

  20. Enhancement of nanofibrous scaffold of multiwalled carbon nanotubes/polyurethane composite to the fibroblasts growth and biosynthesis.

    Science.gov (United States)

    Meng, Jie; Kong, Hua; Han, Zhaozhao; Wang, Chaoying; Zhu, Guangjin; Xie, Sishen; Xu, Haiyan

    2009-01-01

    In this work, the effect of nanofibrous structure and multiwalled carbon nanotubes (MWNTs) incorporation in the polyurethane (PU) on the fibroblasts growth behavior was studied. The nanofibrous scaffold of multiwalled carbon nanotubes and polyurethane composite (MWNT/PU) with an average fiber diameter of 300-500 nm was fabricated by electrospinning technique. The nanofibrous scaffold of PU, smooth film of PU, and MWNT/PU were also prepared as controls. Cell viability assay, laser confocal microscopy, and scanning electron microscopy were applied to evaluate cell adhesion, proliferation, and cytoskeletal development on the scaffolds, respectively. Cell-released protein was analyzed by Bradford protein assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), mass spectrometry, and transwell assay, respectively. Experimental results demonstrated that the scaffold with nanofibrous structure and MWNTs incorporation exhibited highest enhancement not only to the cell adhesion and proliferation but also to the cell migration and aggregation. Besides, cells cultured on the nanofibrous scaffold of MWNT/PU released the largest amount of proteins including collagen in comparison with those on the other substrates. Hence, the nanofibrous architecture and MWNTs incorporation provided favorite interactions to the cells, which implied the application potentials of the nanofibrous composite for tissue repair and regeneration.

  1. Development of Carbon Nanotube-Based Sensor to Monitor Crack Growth in Cracked Aluminum Structures Underneath Composite Patching

    Science.gov (United States)

    2014-06-01

    carbon nanotube/epoxy composites,” Carbon, vol. 44, no. 14, pp. 3022–3029, Nov. 2006. [15] I. D. Rosca and S. V. Hoa , “Highly conductive...nanotube- based sensor- A review,” IEEE Sensors Journal, vol. 7, no. 1-2, pp. 266–284, Jan.–Feb., 2007. [23] M. Nofar, S. V. Hoa and M. D. Pugh

  2. Studies of Carbon Nanotubes

    Science.gov (United States)

    Caneba, Gerard T.

    2005-01-01

    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.

  3. The role of H2 reduction in the growth of single-walled carbon nanotubes

    Science.gov (United States)

    Yuca, Neslihan; Gümüş, Fatih; Karatepe, Nilgün

    2013-09-01

    Carbon nanotubes (CNTs) with their high mechanical, electrical, thermal and chemical properties are regarded as promising materials for many different potential applications. Chemical vapor deposition (CVD) is a common method for CNT synthesis especially for mass production. There are important parameters (synthesis temperature, catalyst and calcination conditions, substrate, carbon source, synthesis time, H2 reduction, etc.) affecting the structure, morphology and the amount of the CNT synthesis. In this study, CNTs were synthesized by CVD of acetylene (C2H2) on magnesium oxide (MgO) powder substrate impregnated by iron nitrate (Fe (NO3)3•9H2O) solution. The synthesis conditions were as follows: at catalyst calcination temperatures of 400 and 550°C, calcination time of 0, 15, 30 and 45 min, hydrogen concentrations of 0, 50 and 100 % vol, synthesis temperature of 800°C and synthesis time of 30 minutes. The synthesized materials were characterized by thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), X ray diffraction (XRD) and Raman spectroscopy. Effects of H2 reduction on catalyst calcination and CNT synthesis were investigated.

  4. Ultrafast growth of carbon nanotubes on graphene for capacitive energy storage

    Science.gov (United States)

    Li, Zijiong; Yang, Baocheng; Su, Yuling; Wang, Haiyan; Groeper, Jonathan

    2016-01-01

    We have demonstrated a novel three-dimensional (3D) architecture of a graphene/carbon nanotube (G-CNT) hybrid synthesized at large scale within just 5 s via a simple microwave-heating method without the usage of any other conducting or expanding agent for the first time. The carbon composites obtained consist of evenly grown CNTs with an average diameter of about 15 nm on the surface of graphene nanosheets. The G-CNT hybrid exhibits enhanced electrochemical performance for both aqueous and organic supercapacitor devices. Particularly, the G-CNT electrodes demonstrate an enhanced specific capacitance of 361 F g-1 at a current density of 1.1 A g-1 in an aqueous electrolyte and a volumetric capacitance of 254 F cm-3 in an organic electrolyte. They also display excellent cycle stability with nearly 91.2% of the initial capacitance retained after 10 000 charging-discharging cycles at a current density of 15 A g-1. This demonstrates that the developed composites have potential applications in supercapacitors and other energy storage devices.

  5. Luminescence of carbon nanotube bulbs

    Institute of Scientific and Technical Information of China (English)

    LI ChuanGang; WU DeHai; WANG KunLin; WEI JinQuan; WEI BingQing; ZHU HongWei; WANG ZhiCheng; LUO JianBin; LIU WenJin; ZHENG MingXin

    2007-01-01

    Carbon nanotube (CNT) bulbs made of decimeter-scale double-walled carbon nanotube (DWCNT) strands and films were fabricated and their luminescence properties, including the lighting efficiency, voltage-current relation and thermal stability were investigated. The results show that the DWCNT bulb has a comparable spectrum of visible light with tungsten bulb and its average efficiency is 40% higher than that of a tungsten filament at the same temperature (1400-2300 K). The nanotube filaments show both resistance and thermal stability over a large temperature region. No obvious damage was found for a nanotube bulb illuminating at 2300 K for more than 24 hours in vacuum.

  6. CARBON NANOTUBES: PROPERTIES AND APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, John, E.

    2009-07-24

    Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in common with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms. One of

  7. Carbon nanotube ecotoxicity in amphibians: assessment of multiwalled carbon nanotubes and comparison with double-walled carbon nanotubes.

    Science.gov (United States)

    Mouchet, Florence; Landois, Perine; Puech, Pascal; Pinelli, Eric; Flahaut, Emmanuel; Gauthier, Laury

    2010-08-01

    The potential impact of industrial multiwalled carbon nanotubes (MWNTs) was investigated under normalized laboratory conditions according to the International Standard micronucleus assay ISO 21427-1 for 12 days of half-static exposure to 0.1, 1, 10 and 50 mg/l of MWNTs in water. Three different end points were carried out for 12 days of exposure: mortality, growth inhibition and micronuclei induction in erythrocytes of the circulating blood of larvae. Raman spectroscopy analysis was used to study the presence of carbon nanotubes in the biological samples. Considering the high diversity of carbon nanotubes according to their different characteristics, MWNTs were analyzed in Xenopus larvae, comparatively to double-walled carbon nanotubes used in a previous study in similar conditions. Growth inhibition in larvae exposed to 50 mg/l of MWNTs was evidenced; however, no genetoxicity (micronucleus assay) was noticed, at any concentration. Carbon nanotube localization in the larvae leads to different possible hypothesis of mechanisms explaining toxicity in Xenopus.

  8. Synthesis of Aligned Carbon Nanotubes by Thermal Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Gang; ZHOU Ming; MA Weiwei; CAI Lan

    2009-01-01

    Single crystal silicon was found to be very beneficial to the growth of aligned carbon nanotubes by chemical vapor deposition with C2H2 as carbon source. A thin film of Ni served as catalyst was deposited on the Si substrate by the K575X Peltier Cooled High Resolution Sputter Coater before growth. The growth properties of carbon nanotubes were studied as a function of the Ni catalyst layer thickness. The diameter, growth rate and areal density of the carbon nanotubes were controlled by the initial thickness of the catalyst layer. Steric hindrance between nanotubes forces them to grow in well-aligned manner at an initial stage of growth. Transmission electron microscope analysis revealed that nanotubes grew by a tip growth mechanism.

  9. Polymerization initated at sidewalls of carbon nanotubes

    Science.gov (United States)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

    2011-01-01

    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  10. Synthesis, characterisation and applications of coiled carbon nanotubes.

    Science.gov (United States)

    Hanus, Monica J; Harris, Andrew T

    2010-04-01

    Coiled carbon nanotubes are helical carbon structures formed when heptagonal and pentagonal rings are inserted into the hexagonal backbone of a 'straight' nanotube. Coiled carbon nanotubes have been reported with both regular and irregular helical structures. In this work the structure, growth mechanism(s), synthesis, properties and potential applications of coiled carbon nanotubes are reviewed. Published data suggests that coiled carbon nanotube synthesis occurs due to nonuniform extrusion of carbon from a catalyst surface. To date, coiled carbon nanotubes have been synthesised using catalyst modification techniques including: (i) the addition of S or P containing compounds during synthesis; (ii) the use of binary or ternary metal catalysts; (iii) the use of microwaves to create a local temperature gradient around individual catalyst particles and; (iv) the use of pH control during catalyst preparation. In most instances coiled carbon nanotubes are produced as a by-product; high yield and/or large-scale synthesis of coiled carbon nanotubes remains problematic. The qualitative analysis of coiled carbon nanotubes is currently hindered by the absence of specific characterisation data in the literature, e.g., oxidation profiles measured by thermogravimetric analysis and Raman spectra of pure coiled carbon nanotube samples.

  11. Carbon Nanotube Biosensors

    Directory of Open Access Journals (Sweden)

    Carmen-Mihaela eTilmaciu

    2015-10-01

    Full Text Available Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  12. Carbon nanotube biosensors

    Science.gov (United States)

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  13. Aligned, isotropic and patterned carbon nanotube substrates that control the growth and alignment of Chinese hamster ovary cells

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Che Azurahanim Che; Asanithi, Piyapong; Brunner, Eric W; Jurewicz, Izabela; Bo, Chiara; Sear, Richard P; Dalton, Alan B [Department of Physics and Surrey Materials Institute, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Azad, Chihye Lewis; Ovalle-Robles, Raquel; Fang Shaoli; Lima, Marcio D; Lepro, Xavier; Collins, Steve; Baughman, Ray H, E-mail: r.sear@surrey.ac.uk [Alan G MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX 75080-3021 (United States)

    2011-05-20

    Here we culture Chinese hamster ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes. This control over cell alignment is required for tissue engineering; almost all tissues consist of oriented cells. The aligned substrates are made using straightforward physical chemistry techniques from forests of multiwall nanotubes; no lithography is required to make inexpensive large-scale substrates with highly aligned nanoscale grooves. Interestingly, although the cells strongly align with the nanoscale grooves, only a few also elongate along this axis: alignment of the cells does not require a pronounced change in morphology of the cell. We also pattern the nanotube bundles over length scales comparable to the cell size and show that the cells follow this pattern.

  14. Aligned, isotropic and patterned carbon nanotube substrates that control the growth and alignment of Chinese hamster ovary cells

    Science.gov (United States)

    Azurahanim Che Abdullah, Che; Asanithi, Piyapong; Brunner, Eric W.; Jurewicz, Izabela; Bo, Chiara; Azad, Chihye Lewis; Ovalle-Robles, Raquel; Fang, Shaoli; Lima, Marcio D.; Lepro, Xavier; Collins, Steve; Baughman, Ray H.; Sear, Richard P.; Dalton, Alan B.

    2011-05-01

    Here we culture Chinese hamster ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes. This control over cell alignment is required for tissue engineering; almost all tissues consist of oriented cells. The aligned substrates are made using straightforward physical chemistry techniques from forests of multiwall nanotubes; no lithography is required to make inexpensive large-scale substrates with highly aligned nanoscale grooves. Interestingly, although the cells strongly align with the nanoscale grooves, only a few also elongate along this axis: alignment of the cells does not require a pronounced change in morphology of the cell. We also pattern the nanotube bundles over length scales comparable to the cell size and show that the cells follow this pattern.

  15. Atomic transportation via carbon nanotubes.

    Science.gov (United States)

    Wang, Quan

    2009-01-01

    The transportation of helium atoms in a single-walled carbon nanotube is reported via molecular dynamics simulations. The efficiency of the atomic transportation is found to be dependent on the type of the applied loading and the loading rate as well as the temperature in the process. Simulations show the transportation is a result of the van der Waals force between the nanotube and the helium atoms through a kink propagation initiated in the nanotube.

  16. A Comparative Study of Three Different Chemical Vapor Deposition Techniques of Carbon Nanotube Growth on Diamond Films

    Directory of Open Access Journals (Sweden)

    Betty T. Quinton

    2013-01-01

    Full Text Available This paper compares between the methods of growing carbon nanotubes (CNTs on diamond substrates and evaluates the quality of the CNTs and the interfacial strength. One potential application for these materials is a heat sink/spreader for high-power electronic devices. The CNTs and diamond substrates have a significantly higher specific thermal conductivity than traditional heat sink/spreader materials making them good replacement candidates. Only limited research has been performed on these CNT/diamond structures and their suitability of different growth methods. This study investigates three potential chemical vapor deposition (CVD techniques for growing CNTs on diamond: thermal CVD (T-CVD, microwave plasma-enhanced CVD (MPE-CVD, and floating catalyst thermal CVD (FCT-CVD. Scanning electron microscopy (SEM and high-resolution transmission electron microscopy (TEM were used to analyze the morphology and topology of the CNTs. Raman spectroscopy was used to assess the quality of the CNTs by determining the ID/IG peak intensity ratios. Additionally, the CNT/diamond samples were sonicated for qualitative comparisons of the durability of the CNT forests. T-CVD provided the largest diameter tubes, with catalysts residing mainly at the CNT/diamond interface. The MPE-CVD process yielded non uniform defective CNTs, and FCT-CVD resulted in the smallest diameter CNTs with catalyst particles imbedded throughout the length of the nanotubes.

  17. Gas-Phase Growth of Heterostructures of Carbon Nanotubes and Bimetallic Nanowires

    Directory of Open Access Journals (Sweden)

    Whi Dong Kim

    2011-01-01

    Full Text Available A simple, inexpensive, and viable method for growing multiple heterostructured carbon nanotubes (CNTs over the entire surface of Ni-Al bimetallic nanowires (NWs in the gas phase was developed. Polymer-templated bimetallic nitrate NWs were produced by electrospinning in the first step, and subsequent calcination resulted in the formation of bimetallic oxide NWs by thermal decomposition. In the second step, free-floating bimetallic NWs were produced by spray pyrolysis in an environment containing hydrogen gas as a reducing gas. These NWs were continuously introduced into a thermal CVD reactor in order to grow CNTs in the gas phase. Scanning electron microscopy (SEM, transmission electron microscopy (TEM, and Raman spectrometry analyses revealed that the catalytic Ni sites exposed in the non-catalytic Al matrix over the entire surface of the bimetallic NWs were seeded to radially grow highly graphitized CNTs, which resembled “foxtail” structures. The grown CNTs were found to have a relatively uniform diameter of approximately 10±2 nm and 10 to 15 walls with a hollow core. The average length of the gas-phase-grown CNTs can be controlled between 100 and 1000 nm by adjusting the residence time of the free-floating bimetallic NWs in the thermal CVD reactor.

  18. Hydroxyapatite growth on multiwall carbon nanotubes grown on titanium fibers from a titanium sheet

    KAUST Repository

    Chetibi, Loubna

    2013-09-27

    Nano-hydroxyapatite (HA) was grown on functionalized multiwalled carbon nanotubes (MWCNTs) deposited on TiO2 nanofibers (NFs) that were hydrothermally grown on Ti metal sheets. The HA was electrochemically grown on the MWCNTs/TiO2 porous layer. It was found that the HA grows on the MWCNTs/TiO2 NFs in the form of dense coating with nanorice grain-shaped. The incorporation of MWCNTs between HA and TiO2 NFs has led to higher adhesion strength as measured by micro-scratching test indicating the benefit of MWCNTs on the improving the bonding strength of HA layer. The obtained coatings exhibit excellent corrosion resistance in simulated body fluid. It is expected that this simple route for preparing the new HA/MWCNTs/TiO2/Ti-layered structure might be used not only in the biomedical field, but also in catalysis and biological sensing among others. © 2013 Springer Science+Business Media New York.

  19. Effect of Lanthanum on Catalytic Growth of Carbon Nanotubes from Methane over Nickel-Aluminum Catalyst

    Institute of Scientific and Technical Information of China (English)

    Ju Yan; Li Fengyi; Wei Renzhong; Rao Richuan

    2004-01-01

    The synthesis of carbon nanotubes (CNTs) from methane decomposition by Ni-La-Al (Ni/La/Al = 10: 1:9) and Ni-Al (Ni/A1 = 1:1 ) catalysts at 1023 K was studied.Catalysts were prepared by a co-precipitation method.During the methane decomposition, a part of gases at the exit of the reactor was analyzed by gas chromatography.The experimental results show that doping La into Ni-A1 catalyst improves the catalytic lifetime and the yields of CNTs in the methane decomposition.Some characteristics of CNTs were investigated by TEM and XRD.The analyses show that CNTs deposited on the Ni-La-A1 catalyst have obvious thinner walls, less bend structures and better graphitization than the sample grown over Ni-Al.These results indicate that the introduction of lanthanum into the nickel-aluminum catalyst leads to significant changes in the morphology and microstructures of the CNTs.

  20. Directional neurite growth using carbon nanotube patterned substrates as a biomimetic cue

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Min Jee; Nam, Yoonkey [Department of Bio and Brain Engineering, KAIST, Daejeon (Korea, Republic of); Namgung, Seon; Hong, Seunghun, E-mail: seunghun@snu.ac.kr, E-mail: ynam@kaist.ac.kr [Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)

    2010-06-11

    Researchers have made extensive efforts to mimic or reverse-engineer in vivo neural circuits using micropatterning technology. Various surface chemical cues or topographical structures have been proposed to design neuronal networks in vitro. In this paper, we propose a carbon nanotube (CNT)-based network engineering method which naturally mimics the structure of extracellular matrix (ECM). On CNT patterned substrates, poly-L-lysine (PLL) was coated, and E18 rat hippocampal neurons were cultured. In the early developmental stage, soma adhesion and neurite extension occurred in disregard of the surface CNT patterns. However, later the majority of neurites selectively grew along CNT patterns and extended further than other neurites that originally did not follow the patterns. Long-term cultured neuronal networks had a strong resemblance to the in vivo neural circuit structures. The selective guidance is possibly attributed to higher PLL adsorption on CNT patterns and the nanomesh structure of the CNT patterns. The results showed that CNT patterned substrates can be used as novel neuronal patterning substrates for in vitro neural engineering.

  1. Method for synthesizing carbon nanotubes

    Science.gov (United States)

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  2. Carbon nanotubes: engineering biomedical applications.

    Science.gov (United States)

    Gomez-Gualdrón, Diego A; Burgos, Juan C; Yu, Jiamei; Balbuena, Perla B

    2011-01-01

    Carbon nanotubes (CNTs) are cylinder-shaped allotropic forms of carbon, most widely produced under chemical vapor deposition. They possess astounding chemical, electronic, mechanical, and optical properties. Being among the most promising materials in nanotechnology, they are also likely to revolutionize medicine. Among other biomedical applications, after proper functionalization carbon nanotubes can be transformed into sophisticated biosensing and biocompatible drug-delivery systems, for specific targeting and elimination of tumor cells. This chapter provides an introduction to the chemical and electronic structure and properties of single-walled carbon nanotubes, followed by a description of the main synthesis and post-synthesis methods. These sections allow the reader to become familiar with the specific characteristics of these materials and the manner in which these properties may be dependent on the specific synthesis and post-synthesis processes. The chapter ends with a review of the current biomedical applications of carbon nanotubes, highlighting successes and challenges.

  3. Morphology, structure and Raman scattering of carbon nanotubes produced by using mesoporous materials

    Institute of Scientific and Technical Information of China (English)

    解思深; 李文治; 王超英; 徐丽雯; 张昊; 张云; 钱露茜

    1997-01-01

    Carbon nanotubes were prepared by chemical vapor deposition (CVD) of hydrocarbon gas on various substrates.The effect of substrates on the growth,morphology and structure of carbon nanotubes were investigated.Aligned carbon nanotubes with high density and purity were achieved by CVD on mesoporous silica substrate.The Raman scattering of aligned carbon nanotubes was carried out,and the dependence of the phonon properties on the mi-crostructure of the nanotubes has been discussed.

  4. Rapid synthesis of CNTs@MIL-101(Cr) using multi-walled carbon nanotubes (MWCNTs) as crystal growth accelerator☆

    Institute of Scientific and Technical Information of China (English)

    Qing Wang; Shengqiang Wang; Hongbing Yu

    2016-01-01

    In this work, hybrid material CNTs@MIL-101(Cr) was synthesized in 2 h using multi-wal ed carbon nanotubes (MWCNTs) as the crystal growth accelerator with hydrothermal method. The characteristic differences between the crystals of CNTs@MIL-101(Cr) and MIL-101 were investigated by N2 adsorption–desorption isotherms, X-ray diffraction (XRD), scanning electron microscope (SEM) and thermogravimetric analyzer (TGA). The results showed that MWCNTs embedding in the hybrid material provide more mesoporous volumes than that of MIL-101. Moreover, the fast synthesized crystals of CNTs@MIL-101(Cr) still preserve the octahedral shape like MIL-101 and have a larger size ranging from 1.5 to 2.0μm which were approximately three times larger than that of MIL-101. In the proposed mechanism, the roles of MWCNTs played in the crystal ization were discussed where MWCNTs can be seen as coaxial cylindrical tubes composed of multi-layer graphenes and the place where nucleation and crystal growth processes occur at the tubes' out surface. Then, a crystal seeding layer bonding with the MWCNTs may be easily formed which accelerates the growth rate of MIL-101 crystals. Thus, larger crystals of CNTs@MIL-101(Cr) were formed due to the faster crystal growth rate of MIL-101.

  5. Modeling of HiPco Process for Carbon Nanotube Production

    Science.gov (United States)

    Gokcen, T.; Dateo, C. E.; Meyyappan, M.; Colbert, D. T.; Smith, D. T.; Smith, K.; Smalley, R. E.; Arnold, James O. (Technical Monitor)

    2000-01-01

    High-pressure carbon monoxide (HiPco) reactor, developed at Rice University, is used to produce single-walled carbon nanotubes (SWNT) from gas-phase reactions of iron carbonyl and nickel carbonyl in carbon monoxide at high pressures (10 - 100 atm). Computational modeling is used to better understand the HiPco process. In the present model, decomposition of the precursor, metal cluster formation and growth, and carbon nanotube growth are addressed. Decomposition of precursor molecules is necessary to initiate metal cluster formation. The metal clusters serve as catalysts for carbon nanotube growth. Diameter of metal clusters and number of atoms in these clusters are some of the essential information for predicting carbon nanotube formation and growth, which is then modeled by Boudouard reaction (2CO ---> C(s) + CO2) with metal catalysts. The growth kinetic model is integrated with a two-dimensional axisymmetric reactor flow model to predict reactor performance.

  6. Aligned carbon nanotubes for nanoelectronics

    Science.gov (United States)

    Choi, Won Bong; Bae, Eunju; Kang, Donghun; Chae, Soodoo; Cheong, Byung-ho; Ko, Ju-hye; Lee, Eungmin; Park, Wanjun

    2004-10-01

    We discuss the central issues to be addressed for realizing carbon nanotube (CNT) nanoelectronics. We focus on selective growth, electron energy bandgap engineering and device integration. We have introduced a nanotemplate to control the selective growth, length and diameter of CNTs. Vertically aligned CNTs are synthesized for developing a vertical CNT-field effect transistor (FET). The ohmic contact of the CNT/metal interface is formed by rapid thermal annealing. Diameter control, synthesis of Y-shaped CNTs and surface modification of CNTs open up the possibility for energy bandgap modulation. The concepts of an ultra-high density transistor based on the vertical-CNT array and a nonvolatile memory based on the top gate structure with an oxide-nitride-oxide charge trap are also presented. We suggest that the deposited memory film can be used for the quantum dot storage due to the localized electric field created by a nano scale CNT-electron channel.

  7. Improved Method of Purifying Carbon Nanotubes

    Science.gov (United States)

    Delzeit, Lance D.

    2004-01-01

    An improved method of removing the residues of fabrication from carbon nanotubes has been invented. These residues comprise amorphous carbon and metal particles that are produced during the growth process. Prior methods of removing the residues include a variety of processes that involved the use of halogens, oxygen, or air in both thermal and plasma processes. Each of the prior methods entails one or more disadvantages, including non-selectivity (removal or damage of nanotubes in addition to removal of the residues), the need to dispose of toxic wastes, and/or processing times as long as 24 hours or more. In contrast, the process described here does not include the use of toxic chemicals, the generation of toxic wastes, causes little or no damage to the carbon nanotubes, and involves processing times of less than 1 hour. In the improved method, purification is accomplished by flowing water vapor through the reaction chamber at elevated temperatures and ambient pressures. The impurities are converted to gaseous waste products by the selective hydrogenation and hydroxylation by the water in a reaction chamber. This process could be performed either immediately after growth or in a post-growth purification process. The water used needs to be substantially free of oxygen and can be obtained by a repeated freeze-pump-thaw process. The presence of oxygen will non-selectively attach the carbon nanotubes in addition to the amorphous carbon.

  8. Functionalization of Carbon Nanotubes

    Science.gov (United States)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2009-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  9. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  10. Carbon nanotube biconvex microcavities

    Science.gov (United States)

    Butt, Haider; Yetisen, Ali K.; Ahmed, Rajib; Yun, Seok Hyun; Dai, Qing

    2015-03-01

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2-3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  11. Enhanced Carbon Nanotube Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation utilizes carbon nanotubes (CNTs) coated with pseudo-capacitive MnO2 material as nano-composite electrode and ionic electrolyte for the...

  12. Carbon nanotubes for coherent spintronics

    DEFF Research Database (Denmark)

    Kuemmeth, Ferdinand; Churchill, H O H; Herring, P K;

    2010-01-01

    Carbon nanotubes bridge the molecular and crystalline quantum worlds, and their extraordinary electronic, mechanical and optical properties have attracted enormous attention from a broad scientific community. We review the basic principles of fabricating spin-electronic devices based on individua...

  13. A new mechanism for carbon nanotube evolution

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Key discoveries on the growth mechanism of carbon nanotubes(CNTs) have recently been achieved by CAS researcher ZHU Zhenping and his research group at the State Key Laboratory of Coal Conversion,the Institute of Coal Chemistry of CAS, funded by the National Natural Science Foundation of China and the CAS Bairen Program.

  14. Dynamic study of carbon nanotube growth and catalyst morphology evolution during acetylene decomposition on Co/SBA-15 in an environmental TEM

    DEFF Research Database (Denmark)

    s Aires, F. J. Cadete Santo; Epicier, T.; Wagner, Jakob Birkedal

    2012-01-01

    -3/10-2 mbar range was used to decrease the growth rate to allow real-time observation of the formation of CNTs over several minutes. These conditions also reduced the coking of the nanoparticles and favoured the formation of tubular structures. Two types of CNTs following the tip-growth mechanism......In situ studies of micro- and nano-objects in their characteristic environment have been performed ever since the early days of electron microscopy [1]. Over several decades the in situ observation of the synthesis of filamentous carbon (nanotubes/nanofilaments) during hydrocarbon decomposition has...... been one of the most popular topics [2] for investigation in the environmental transmission electron microscope (ETEM). In this work we study the growth of carbon nanotubes (CNTs) by the decomposition of acetylene on Co nanoparticles inserted into mesoporous silicas (SBA-15) using both conventional...

  15. Hydroxyl radical induced photo-transformation of single-walled carbon nanotubes in the aquatic environment

    Science.gov (United States)

    Inevitably, the growth in production of carbon nanotubes will translate into their release into our environment, yet existing information about their fate and persistence is limited. We hypothesize that indirect photochemical transformation of unfunctionalized carbon nanotubes is...

  16. Direct growth of single-walled carbon nanotubes on conducting ZnO films and its field emission properties

    Science.gov (United States)

    Min, Yo-Sep; Bae, Eun Ju; Kim, Un Jeong; Park, Wanjun; Hwang, Cheol Seong

    2006-09-01

    Despite the necessity of direct growth of single-walled carbon nanotubes (SWNTs) on conducting films for versatility of designing device architectures for nanoelectronics and optoelectronics, most of SWNT growths have been carried out on insulating films or supporting materials such as SiO2 and Al2O3. Here, the authors report that conducting ZnO films can be used as both an underlying layer for the SWNT growth and an electrode for device operation. ZnO films with a resistivity in the order of 10-3Ωcm were deposited by atomic layer deposition. SWNTs were directly grown on the ZnO film by water plasma chemical vapor deposition. The authors demonstrate field emission properties from the SWNT/ZnO cathode, of which the turn-on electric field for a current density of 10μA /cm2 and the field enhancement factor are 1.8V/μm and 3200, respectively.

  17. Molybdenum Disulfide Sheathed Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xu Chun SONG; Zhu De XU; Yi Fan ZHENG; Gui HAN; Bo LIU; Wei Xiang CHEN

    2004-01-01

    Single and double layered MoS2-coated multiwalled carbon nanotubes (MWCNs) were successfully prepared by pyrolyzing (NH4)2MoS4-coated multiwalled carbon nanotubes in an H2 atmosphere at 900℃. MoS2-coated MWCNs would be expected to have different tribological and mechanical properties compared to MoS2, so it may have potential applications in many fields.

  18. Selective functionalization of carbon nanotubes

    Science.gov (United States)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  19. Carbon nanotubes for coherent spintronics

    DEFF Research Database (Denmark)

    Kuemmeth, Ferdinand; Churchill, H O H; Herring, P K

    2010-01-01

    Carbon nanotubes bridge the molecular and crystalline quantum worlds, and their extraordinary electronic, mechanical and optical properties have attracted enormous attention from a broad scientific community. We review the basic principles of fabricating spin-electronic devices based on individual......, electrically-gated carbon nanotubes, and present experimental efforts to understand their electronic and nuclear spin degrees of freedom, which in the future may enable quantum applications....

  20. Carbon nanotubes in neuroregeneration and repair.

    Science.gov (United States)

    Fabbro, Alessandra; Prato, Maurizio; Ballerini, Laura

    2013-12-01

    In the last decade, we have experienced an increasing interest and an improved understanding of the application of nanotechnology to the nervous system. The aim of such studies is that of developing future strategies for tissue repair to promote functional recovery after brain damage. In this framework, carbon nanotube based technologies are emerging as particularly innovative tools due to the outstanding physical properties of these nanomaterials together with their recently documented ability to interface neuronal circuits, synapses and membranes. This review will discuss the state of the art in carbon nanotube technology applied to the development of devices able to drive nerve tissue repair; we will highlight the most exciting findings addressing the impact of carbon nanotubes in nerve tissue engineering, focusing in particular on neuronal differentiation, growth and network reconstruction.

  1. General hypothesis and shell model for the synthesis of semiconductor nanotubes, including carbon nanotubes

    Science.gov (United States)

    Mohammad, S. Noor

    2010-09-01

    Semiconductor nanotubes, including carbon nanotubes, have vast potential for new technology development. The fundamental physics and growth kinetics of these nanotubes are still obscured. Various models developed to elucidate the growth suffer from limited applicability. An in-depth investigation of the fundamentals of nanotube growth has, therefore, been carried out. For this investigation, various features of nanotube growth, and the role of the foreign element catalytic agent (FECA) in this growth, have been considered. Observed growth anomalies have been analyzed. Based on this analysis, a new shell model and a general hypothesis have been proposed for the growth. The essential element of the shell model is the seed generated from segregation during growth. The seed structure has been defined, and the formation of droplet from this seed has been described. A modified definition of the droplet exhibiting adhesive properties has also been presented. Various characteristics of the droplet, required for alignment and organization of atoms into tubular forms, have been discussed. Employing the shell model, plausible scenarios for the formation of carbon nanotubes, and the variation in the characteristics of these carbon nanotubes have been articulated. The experimental evidences, for example, for the formation of shell around a core, dipole characteristics of the seed, and the existence of nanopores in the seed, have been presented. They appear to justify the validity of the proposed model. The diversities of nanotube characteristics, fundamentals underlying the creation of bamboo-shaped carbon nanotubes, and the impurity generation on the surface of carbon nanotubes have been elucidated. The catalytic action of FECA on growth has been quantified. The applicability of the proposed model to the nanotube growth by a variety of mechanisms has been elaborated. These mechanisms include the vapor-liquid-solid mechanism, the oxide-assisted growth mechanism, the self

  2. The Effect of Alumina and Magnesia Supported Germanium Nanoparticles on the Growth of Carbon Nanotubes in the Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    Ghazaleh Allaedini

    2015-01-01

    Full Text Available The effect of alumina and magnesia supported germanium (Ge nanoparticles on the synthesis of carbon nanotubes (CNTs using the chemical vapor deposition (CVD method in atmospheric pressure was investigated. The TEM micrographs confirmed the formation of carbon nanotubes, and the field emission scanning electron microscopy (FESEM analysis suggested a tip-growth mechanism for the grown carbon nanotubes. The X-ray diffraction (XRD pattern indicated a graphitic nature of the carbon nanotubes. The obtained CNTs using Ge nanoparticles supported by MgO resulted in a higher degree of graphitization than the CNTs obtained using Ge nanoparticles supported by Al2O3. Raman spectroscopy analysis of the CNTs confirmed the presence of radial breathing modes (RBM, which verified the formation of CNTs. High frequency Raman analysis demonstrated that the degree of graphitization of the synthesized CNTs using magnesia supported Ge nanoparticles is higher than that of the alumina supported Ge nanoparticles with the values of (ID/IG ratios equal to 0.45 and 0.73, respectively.

  3. Effect of substrate material on the growth and field emission characteristics of large-area carbon nanotube forests

    Energy Technology Data Exchange (ETDEWEB)

    Ummethala, Raghunandan; Täschner, Christine; Leonhardt, Albrecht; Büchner, Bernd [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Wenger, Daniela; Tedde, Sandro F. [Siemens Healthcare GmbH, Technology Centre, Guenther-Scharowsky-Strasse 1, 91058 Erlangen (Germany); Eckert, Jürgen [Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstrasse 12, A-8700 Leoben (Austria); Department Materials Physics, Montanuniversität Leoben, Jahnstraße 12, A-8700 Leoben (Austria)

    2016-01-28

    Carbon nanotubes (CNTs) are a promising replacement for tungsten filaments as electron emitters in conventional x-ray sources, owing to their higher aspect ratio, superior mechanical stability, chemical inertness, and high electrical and thermal conductivities. Conditions for realizing the best emission behavior from CNTs have been formulated over the last few years. In this paper, we report the relatively less-investigated factor, namely, the influence of the nature of substrate material on the growth as well as field emission characteristics of large-area multiwalled CNTs for their practical application in medical x-ray sources. We compare the morphology of CNTs on a variety of substrates such as stainless steel, copper, molybdenum, graphite, few-layer graphene, and carbon nanowalls grown by thermal chemical vapor deposition following a simple drop-coating of catalyst. We find that CNTs grown on stainless steel and graphite show the best combination of emission characteristics under pulsed operation mode. These studies are helpful in selecting the optimum substrate material for field emission applications. Ex situ studies on field emission degradation of CNTs are presented towards the end.

  4. Effect of substrate material on the growth and field emission characteristics of large-area carbon nanotube forests

    Science.gov (United States)

    Ummethala, Raghunandan; Wenger, Daniela; Tedde, Sandro F.; Täschner, Christine; Leonhardt, Albrecht; Büchner, Bernd; Eckert, Jürgen

    2016-01-01

    Carbon nanotubes (CNTs) are a promising replacement for tungsten filaments as electron emitters in conventional x-ray sources, owing to their higher aspect ratio, superior mechanical stability, chemical inertness, and high electrical and thermal conductivities. Conditions for realizing the best emission behavior from CNTs have been formulated over the last few years. In this paper, we report the relatively less-investigated factor, namely, the influence of the nature of substrate material on the growth as well as field emission characteristics of large-area multiwalled CNTs for their practical application in medical x-ray sources. We compare the morphology of CNTs on a variety of substrates such as stainless steel, copper, molybdenum, graphite, few-layer graphene, and carbon nanowalls grown by thermal chemical vapor deposition following a simple drop-coating of catalyst. We find that CNTs grown on stainless steel and graphite show the best combination of emission characteristics under pulsed operation mode. These studies are helpful in selecting the optimum substrate material for field emission applications. Ex situ studies on field emission degradation of CNTs are presented towards the end.

  5. Properties of Carbon Nanotubes

    Science.gov (United States)

    Masood, Samina; Bullmore, Daniel; Duran, Michael; Jacobs, Michael

    2012-10-01

    Different synthesizing methods are used to create various nanostructures of carbon; we are mainly interested in single and multi-wall carbon nanotubes, (SWCNTs) and (MWCNTs) respectively. The properties of these tubes are related to their synthetic methods, chirality, and diameter. The extremely sturdy structure of CNTs, with their distinct thermal and electromagnetic properties, suggests a tremendous use of these tubes in electronics and medicines. Here, we analyze various physical properties of SWCNTs with a special emphasis on electromagnetic and chemical properties. By examining their electrical properties, we demonstrate the viability of discrete CNT based components. After considering the advantages of using CNTs over microstructures, we make a case for the advancement and development of nanostructures based electronics. As for current CNT applications, it's hard to overlook their use and functionality in the development of cancer treatment. Whether the tubes are involved in chemotherapeutic drug delivery, molecular imaging and targeting, or photodynamic therapy, we show that the remarkable properties of SWCNTs can be used in advantageous ways by many different industries.

  6. Carbon nanotube computer.

    Science.gov (United States)

    Shulaker, Max M; Hills, Gage; Patil, Nishant; Wei, Hai; Chen, Hong-Yu; Wong, H-S Philip; Mitra, Subhasish

    2013-09-26

    The miniaturization of electronic devices has been the principal driving force behind the semiconductor industry, and has brought about major improvements in computational power and energy efficiency. Although advances with silicon-based electronics continue to be made, alternative technologies are being explored. Digital circuits based on transistors fabricated from carbon nanotubes (CNTs) have the potential to outperform silicon by improving the energy-delay product, a metric of energy efficiency, by more than an order of magnitude. Hence, CNTs are an exciting complement to existing semiconductor technologies. Owing to substantial fundamental imperfections inherent in CNTs, however, only very basic circuit blocks have been demonstrated. Here we show how these imperfections can be overcome, and demonstrate the first computer built entirely using CNT-based transistors. The CNT computer runs an operating system that is capable of multitasking: as a demonstration, we perform counting and integer-sorting simultaneously. In addition, we implement 20 different instructions from the commercial MIPS instruction set to demonstrate the generality of our CNT computer. This experimental demonstration is the most complex carbon-based electronic system yet realized. It is a considerable advance because CNTs are prominent among a variety of emerging technologies that are being considered for the next generation of highly energy-efficient electronic systems.

  7. Controlled growth of carbon nanotube-graphene hybrid materials for flexible and transparent conductors and electron field emitters.

    Science.gov (United States)

    Nguyen, Duc Dung; Tai, Nyan-Hwa; Chen, Szu-Ying; Chueh, Yu-Lun

    2012-01-21

    We report a versatile synthetic process based on rapid heating and cooling chemical vapor deposition for the growth of carbon nanotube (CNT)-graphene hybrid materials where the thickness of graphene and density of CNTs are properly controlled. Graphene films are demonstrated as an efficient barrier layer for preventing poisoning of iron nanoparticles, which catalyze the growth of CNTs on copper substrates. Based on this method, the opto-electronic and field emission properties of graphene integrated with CNTs can be remarkably tailored. A graphene film exhibits a sheet resistance of 2.15 kΩ sq(-1) with a transmittance of 85.6% (at 550 nm), while a CNT-graphene hybrid film shows an improved sheet resistance of 420 Ω sq(-1) with an optical transmittance of 72.9%. Moreover, CNT-graphene films are demonstrated as effective electron field emitters with low turn-on and threshold electric fields of 2.9 and 3.3 V μm(-1), respectively. The development of CNT-graphene films with a wide range of tunable properties presented in this study shows promising applications in flexible opto-electronic, energy, and sensor devices.

  8. Industrial compatible re-growth of vertically aligned multiwall carbon nanotubes by ultrafast pure oxygen purification process

    DEFF Research Database (Denmark)

    Bu, Ian Y.Y.; Hou, Kai; Engstrøm, Daniel Southcott

    2011-01-01

    Reproducible high-yield purification process of multiwalled carbon nanotubes (CNTs) was developed by thermal annealing in ultrapure oxygen. The optimized condition involves thermal annealing via a PID controlled heater in high purity oxygen at temperature of 450°C for 180s, which burns out...

  9. Developing Single-Wall Carbon Nanotubes into an Industrial Material through the Super-Growth CVD Method

    Science.gov (United States)

    Futaba, Don

    2013-03-01

    Since the discovery of the carbon nanotube (CNT) 20 years ago, extensive effort has been made to utilize their exceptional intrinsic properties toward industrial applications. However, availability has significantly thwarted these endeavors. In one section of my presentation, I will describe our efforts toward the economical mass-production of single-walled carbon nanotubes (SWCNT) based on the water-assisted chemical vapor deposition technique, from which highly efficient synthesis of vertically aligned SWCNTs grow from substrates (SWCNT forests). Further, I will discuss our work to promote the industrial use of SWCNTs as a member of the Technology Research Association for Single-Walled Carbon Nanotubes (TASC) (A consortium of five companies and AIST founded for the specific purpose of developing SWCNT industrial technology.) Specifically, I will present our progress on developing the technology for the synthetic control of SWCNTs and the development of standardized evaluation techniques for the purpose of understanding the relationship between the SWCNT forest structure, e.g. length, density, crystallinity, etc and the targeted property, e.g. conductivity, mechanical reinforcement, etc. Finally, I will present several examples of applications from composites to CNT-based devices. Technology Research Association for Single Wall Carbon Nanotubes (TASC), Japan

  10. Probing Photosensitization by Functionalized Carbon Nanotubes

    Science.gov (United States)

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  11. Synthesis of Carbon Nanotube (CNT Composite Membranes

    Directory of Open Access Journals (Sweden)

    Dusan Losic

    2010-12-01

    Full Text Available Carbon nanotubes are attractive approach for designing of new membranes for advanced molecular separation because of their unique transport properties and ability to mimic biological protein channels. In this work the synthetic approach for fabrication of carbon nanotubes (CNTs composite membranes is presented. The method is based on growth of multi walled carbon nanotubes (MWCNT using chemical vapour deposition (CVD on the template of nanoporous alumina (PA membranes. The influence of experimental conditions including carbon precursor, temperature, deposition time, and PA template on CNT growth process and quality of fabricated membranes was investigated. The synthesis of CNT/PA composites with controllable nanotube dimensions such as diameters (30–150 nm, and thickness (5–100 µm, was demonstrated. The chemical composition and morphological characteristics of fabricated CNT/PA composite membranes were investigated by various characterisation techniques including scanning electron microscopy (SEM, energy-dispersive x-ray spectroscopy (EDXS, high resolution transmission electron microscopy (HRTEM and x-ray diffraction (XRD. Transport properties of prepared membranes were explored by diffusion of dye (Rose Bengal used as model of hydrophilic transport molecule.

  12. Carbon Nanotube Based Molecular Electronics

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  13. Cytotoxicity of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    ZHU Ying; LI WenXin

    2008-01-01

    With large-scale production and application at large scale, carbon nanotubes (CNTs) may cause ad-verse response to the environment and human health. Thus, study on bio-effects and safety of CNTs has attracted great attention from scientists and governments worldwide. This report briefly summa-rizes the main results from the in vitro toxicity study of CNTs. The emphasis is placed on the descrip-tion of a variety of factors affecting CNTs cytotoxicity, including species of CNTs, impurities contained,lengths of CNTs, aspect ratios, chemical modification, and assaying methods of cytotoxicity. However,experimental information obtained thus far on CNTs' cytotoxicity is lacking in comparability, and some-times there is controversy about it. In order to assess more accurately the potential risks of CNTs to human health, we suggest that care should be taken for issues such as chemical modification and quantitative characterization of CNTa in cytotoxicity assessment. More importantly, studies on physical and chemical mechanisms of CNTs' cytotoxicity should be strengthened; assaying methods and evaluating criteria characterized by nanotoxicology should be gradually established.

  14. Cytotoxicity of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    With large-scale production and application at large scale, carbon nanotubes (CNTs) may cause ad-verse response to the environment and human health. Thus, study on bio-effects and safety of CNTs has attracted great attention from scientists and governments worldwide. This report briefly summa-rizes the main results from the in vitro toxicity study of CNTs. The emphasis is placed on the descrip-tion of a variety of factors affecting CNTs cytotoxicity, including species of CNTs, impurities contained, lengths of CNTs, aspect ratios, chemical modification, and assaying methods of cytotoxicity. However, experimental information obtained thus far on CNTs’ cytotoxicity is lacking in comparability, and some-times there is controversy about it. In order to assess more accurately the potential risks of CNTs to human health, we suggest that care should be taken for issues such as chemical modification and quantitative characterization of CNTs in cytotoxicity assessment. More importantly, studies on physical and chemical mechanisms of CNTs’ cytotoxicity should be strengthened; assaying methods and evaluating criteria characterized by nanotoxicology should be gradually established.

  15. Mild in situ growth of platinum nanoparticles on multiwalled carbon nanotube-poly (vinyl alcohol) hydrogel electrode for glucose electrochemical oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shumin; Zheng, Yudong, E-mail: zhengyudong@mater.ustb.edu.cn; Qiao, Kun [University of Science and Technology Beijing, School of Material Science and Engineering (China); Su, Lei [University of Science and Technology Beijing, School of Chemistry and Biological Engineering (China); Sanghera, Amendeep; Song, Wenhui [University College London, UCL Centre for Nanotechnology & Regenerative Medicine, Division of Surgery and Interventional Science (United Kingdom); Yue, Lina; Sun, Yi [University of Science and Technology Beijing, School of Material Science and Engineering (China)

    2015-12-15

    This investigation describes an effective strategy to fabricate an electrochemically active hybrid hydrogel made from platinum nanoparticles that are highly dense, uniformly dispersed, and tightly embedded throughout the conducting hydrogel network for the electrochemical oxidation of glucose. A suspension of multiwalled carbon nanotubes and polyvinyl alcohol aqueous was coated on glassy carbon electrode by electrophoretic deposition and then physically crosslinked to form a three-dimensional porous conductive hydrogel network by a process of freezing and thawing. The network offered 3D interconnected mass-transport channels (around 200 nm) and confined nanotemplates for in situ growth of uniform platinum nanoparticles via the moderate reduction agent, ascorbic acid. The resulting hybrid hydrogel electrode membrane demonstrates an effective method for loading platinum nanoparticles on multiwalled carbon nanotubes by the electrostatic adsorption between multiwalled carbon nanotubes and platinum ions within porous hydrogel network. The average diameter of platinum nanoparticles is 37 ± 14 nm, which is less than the particle size by only using the moderate reduction agent. The hybrid hydrogel electrode membrane-coated glassy carbon electrode showed excellent electrocatalytic activity and good long-term stability toward glucose electrochemical oxidation. The glucose oxidation current exhibited a linear relationship with the concentration of glucose in the presence of chloride ions, promising for potential applications of implantable biofuel cells, biosensors, and electronic devices.

  16. Computational Dynamics of Metal-Carbon Interface-- Key to Controllable Nanotube Growth

    Science.gov (United States)

    2013-11-13

    Report DISTRIBUTION A: Distribution approved for public release. AIR FORCE RESEARCH LABORATORY AF OFFICE OF SCIENTIFIC RESEARCH (AFOSR)/RSA ARLINGTON...the desired types is therefore a crucial scientific goal. Alternatively to the chiral indices n and m, the nanotube type can be described by the... Visualisation of cyclic and multi-branched molecules with VMD. J. Mol. Graph. Model. 2009, 28, 131-139. 50. Humphrey, W.; Dalke, A.; Schulten, K., VMD

  17. Growth of graphite film over the tops of vertical carbon nanotubes using Ni/Ti/Si substrate

    Institute of Scientific and Technical Information of China (English)

    Chia-chih Chuang; Wei-long Liu; Wen-jauh Chen; Jin-hua Huang

    2009-01-01

    A substrate with Ni/Ti/Si structure was used to grow vertical carbon nanotubes (CNTs) with a graphite film over CNT tops by thermal chemical vapor deposition with CH4 gas as carbon source.The carbon nanotubes and the substrate were character-ized by a field emission scanning electron microscope for the morphologies,a transmission electron microscope for the microstruc-tures,a Raman spectrograph for the crystallinity,and an Auger electron spectrometer for the depth distribution of elements.The re-sult shows that when the thickness ratio of Ni layer to Ti layer in substrate is about i,a graphite film with relatively good quality canbe formed on the CNT tops.

  18. Hybrid Composite of Polyaniline Containing Carbon Nanotube

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Carbon nanotube-polyaniline hybrid material was synthesized by emulsion polymerization in-situ. The morphology of hybrid material was studied by TEM and X-ray diffraction. The conductivity of nanocomposite increases with the increasing of carbon nanotube content because of the new conductivity passageways formed by carbon nanotubes.

  19. Synthesis and Application of Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Qun Zeng; Zhenhua Li; Yuhong Zhou

    2006-01-01

    Owing to the unique structure, the superior physical and chemical properties, the super strong mechanical performances, and so on, carbon nanotubes have attracted the attention of researchers all over the world. In this article, the basic properties and the main production processes of carbon nanotubes are introduced in brief, and the progress of applied research for carbon nanotubes is reviewed.

  20. Growth of carbon nanotubes on Si/SiO{sub 2} wafer etched by hydrofluoric acid under different etching durations

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Lling-Lling [Chemical Engineering Discipline, School of Engineering, Monash University, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor (Malaysia); Chai, Siang-Piao, E-mail: chai.siang.piao@monash.edu [Chemical Engineering Discipline, School of Engineering, Monash University, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor (Malaysia); Mohamed, Abdul Rahman [School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, Seri Ampangan, 14300 NibongTebal, Pulau Pinang (Malaysia)

    2012-05-15

    The preparation of SiO{sub 2} nanoparticles for the metal-free catalyst growth of carbon nanotubes (CNTs) was investigated. SiO{sub 2} nanoparticles were generated by etching Si/SiO{sub 2} wafers with 48-50% hydrofluoric acid. Etching duration was varied to study its effects on the generation of the SiO{sub 2} nanoparticles. Atomic force microscopy characterization showed that etching at 1 min was the most effective considering the significant numbers of SiO{sub 2} nanoparticles obtained under this condition. The wafer etched at 1 min after chemical vapor deposition at 900 Degree-Sign C for 1 h demonstrated a low I{sub D}/I{sub G} from Raman analysis which establishes that CNTs with highly ordered graphitic structures were grown. Raman analysis also showed a strong radial breathing mode peak in the low-frequency range for the substrate following the 1 min etching process after the reaction.

  1. Release potential of single-wall carbon nanotubes produced by super-growth method during manufacturing and handling

    Science.gov (United States)

    Ogura, Isamu; Sakurai, Hiromu; Mizuno, Kohei; Gamo, Masashi

    2011-03-01

    We investigated the release potential of single-wall carbon nanotubes (CNTs) produced by the super-growth method during their manufacturing and handling processes at a research facility. We generally sampled air at points both outside and inside of protective enclosures such as a glove box and fume hood. Sampling the air outside of the enclosures was intended to evaluate the actual exposure of workers to CNTs, while sampling the air inside the enclosures was performed to quantify the release of CNTs to the air in order to estimate the potential exposure of workers without protection. The results revealed that airborne CNTs were generated when (1) CNTs were separated from the substrates using a spatula and placed in a container in a glove box; (2) an air gun was used to clean the air filters (containing dust that included CNTs) of a vacuum cleaner; (3) a vacuum cleaner was used to collect CNTs (emission with exhaust air from the cleaner); (4) the container of CNTs was opened; and (5) CNTs in the bin of the cleaner were transferred to a container. In these processes, airborne CNTs were only found inside the enclosures, except for a small amount of CNTs released from the glove box when it was opened. Electron microscopic observations of aerosol particles found CNT clusters, which were fragments of CNT forests, with sizes ranging from submicrometers to tens of micrometers.

  2. Aligned carbon nanotubes physics, concepts, fabrication and devices

    CERN Document Server

    Ren, Zhifeng; Wang, Yang

    2012-01-01

    This book surveys the physics and fabrication of carbon nanotubes and their applications in optics, electronics, chemistry and biotechnology. The text illustrates major fabrication methods in detail, particularly the most widely used PECVD growth techniques.

  3. Hydrodynamic properties of carbon nanotubes.

    Science.gov (United States)

    Walther, J H; Werder, T; Jaffe, R L; Koumoutsakos, P

    2004-06-01

    We study water flowing past an array of single walled carbon nanotubes using nonequilibrium molecular dynamics simulations. For carbon nanotubes mounted with a tube spacing of 16.4 x 16.4 nm and diameters of 1.25 and 2.50 nm, respectively, we find drag coefficients in reasonable agreement with the macroscopic, Stokes-Oseen solution. The slip length is -0.11 nm for the 1.25 nm carbon nanotube, and 0.49 for the 2.50 nm tube for a flow speed of 50 m/s, respectively, and 0.28 nm for the 2.50 nm tube at 200 m/s. A slanted flow configuration with a stream- and spanwise velocity component of 100 ms(-1) recovers the two-dimensional results, but exhibits a significant 88 nm slip along the axis of the tube. These results indicate that slip depends on the particular flow configuration.

  4. Adsorption on the carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    DING Yi; YANG Xiao-bao; NI Jun

    2006-01-01

    Adsorption on single walled carbon nanotubes (SWCNTs) is a subject of growing experimental and theoretical interest.The possible adsorbed patterns of atoms and molecules on the single-walled carbon nanotubes vary with the diameters and chirality of the tubes due to the confinement.The curvature of the carbon nanotube surface enlarges the distance of the adsorbate atoms and thus enhances the stability of high coverage structures of adsorbate.There exist two novel high-coverage stable structures of potassium adsorbed on SWCNTs,which are not stable on graphite.The electronic properties of SWCNTs can be modified by adsorbate atoms and metal-semiconductor and semiconductor-semi-conductor transitions can be achieved by the doping of alkali atoms.

  5. From Bench Top to Market: Growth of Multi-Walled Carbon Nanotubes by Injection CVD Using Fe Organometallics - Production of a Commercial Reactor

    Science.gov (United States)

    Rowsell, J.; Hepp, A. F.; Harris, J. D.; Raffaelle, R. P.; Cowen, J. C.; Scheiman, D. A.; Flood, D. M.; Flood, D. J.

    2009-01-01

    Preferential oriented multiwalled carbon nanotubes were prepared by the injection chemical vapor deposition (CVD) method using either cyclopentadienyliron dicarbonyl dimer or cyclooctatetraene iron tricarbonyl as the iron catalyst source. The catalyst precursors were dissolved in toluene as the carrier solvent for the injections. The concentration of the catalyst was found to influence both the growth (i.e., MWNT orientation) of the nanotubes, as well as the amount of iron in the deposited material. As deposited, the multiwalled carbon nanotubes contained as little as 2.8% iron by weight. The material was deposited onto tantalum foil and fused silica substrates. The nanotubes were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and thermogravimetric analysis. This synthetic route provides a simple and scalable method to deposit MWNTs with a low defect density, low metal content and a preferred orientation. Subsequently, a small start-up was founded to commercialize the deposition equipment. The contrast between the research and entrepreneurial environments will be discussed.

  6. Carbon nanotube-polymer composite actuators

    Science.gov (United States)

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  7. Preparation of very long and open aligned carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    潘正伟; 常保和; 孙连峰; 钱露茜; 刘祖琴; 唐东升; 王刚; 解思深

    2000-01-01

    Very long and open aligned carbon nanotubes that reach about 2 mm long, an order of magnitude longer than previously reached, have been prepared by chemical vapor deposition over silica dioxide substrates on the surface, where iron/silica nano-composite particles are evenly positioned. The nanotubes are naturally opened at the bottom ends. The growth mechanism of the very long and open-ended nanotubes is also discussed.

  8. Synthesis of Carbon Nanotubes by MWPCVD at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    王升高; 汪建华; 王传新; 马志彬; 满卫东

    2002-01-01

    Growth of carbon nanotubes (CNTs) at low temperature is very important to the applications of nanotubes. In this paper, under the catalytic effect of cobalt nanoparticles supported by SiO2, CNTs were synthesized by microwave plasma chemical vapor deposition (MWPCVD)below 500℃. It demonstrates that MWPCVD can be a very efficient process for the synthesis of CNTs at low temperature.

  9. Modified carbon nanotubes and methods of forming carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Heintz, Amy M.; Risser, Steven; Elhard, Joel D.; Moore, Bryon P.; Liu, Tao; Vijayendran, Bhima R.

    2016-06-14

    In this invention, processes which can be used to achieve stable doped carbon nanotubes are disclosed. Preferred CNT structures and morphologies for achieving maximum doping effects are also described. Dopant formulations and methods for achieving doping of a broad distribution of tube types are also described.

  10. Effect of purity, edge length, and growth area on field emission of multi-walled carbon nanotube emitter arrays

    Energy Technology Data Exchange (ETDEWEB)

    Shahi, Monika [Solid State Physics Laboratory, Lucknow Road, Timarpur, Delhi 110054 (India); Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Gautam, S.; Shah, P. V.; Jha, P.; Kumar, P.; Rawat, J. S.; Chaudhury, P. K.; Harsh [Solid State Physics Laboratory, Lucknow Road, Timarpur, Delhi 110054 (India); Tandon, R. P. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2013-05-28

    Present report aims to study the effect of purity, edge length, and growth area on field emission of patterned carbon nanotube (CNT) emitter arrays. For development of four CNT emitter arrays (CEAs), low resistively silicon substrates were coated with thin film of iron catalyst using photolithography, sputtering, and lift off process. Four CEAs were synthesized on these substrates using thermal chemical vapor deposition with minor changes in pretreatment duration. Out of these, two CEAs have 10 {mu}m Multiplication-Sign 10 {mu}m and 40 {mu}m Multiplication-Sign 40 {mu}m solid square dots of CNTs with constant 20 {mu}m inter-dot separation. Other two CEAs have ring square bundles of CNTs and these CEAs are envisioned as 10 {mu}m Multiplication-Sign 10 {mu}m square dots with 4 {mu}m Multiplication-Sign 4 {mu}m scooped out area and 15 {mu}m Multiplication-Sign 15 {mu}m square dots with 5 {mu}m Multiplication-Sign 5 {mu}m lift out area with constant 20 {mu}m inter-dot spacing. Solid square dot structures have exactly constant edge length per unit area with more than four-fold difference in CNT growth area however ring square dot patterns have minor difference in edge length per unit area with approximately two times difference in CNT growth area. Quality and morphology of synthesized CEAs were assessed by scanning electron microscope and Raman characterization which confirm major differences. Field emission of all CEAs was carried out under same vacuum condition and constant inter-electrode separation. Field emission of solid square dot CEAs show approximately identical current density-electric field curves and Fowler-Nordheim plots with little difference in emission current density at same electric field. Similar results were observed for ring square structure CEAs when compared separately. Maximum emission current density observed from these four CEAs reduces from 14.53, 12.23, 11.01, to 8.66 mA/cm{sup 2} at a constant electric field of 5 V/{mu}m, according to edge

  11. Growth of Carbon Nanotubes over Ni Nano-particles Prepared in Situ by Reduction of La2NiO4 Oxides

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel catalyst precursor, La2NiO4, was investigated to synthesize carbon nanotubes, obtained from catalytic disproportionation of CO. The morphology of carbon nanotubes has been examined by TEM (transmission electron micrograph) and SEM (scaning electron micrograph). It was observed that the Ni nano-particle size formed at different reducing temperatures was a key factor to the yield and diameter of carbon nanotubes.

  12. Carbon Micronymphaea: Graphene on Vertically Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Jong Won Choi

    2013-01-01

    Full Text Available This paper describes the morphology of carbon nanomaterials such as carbon nanotube (CNT, graphene, and their hybrid structure under various operating conditions during a one-step synthesis via plasma-enhanced chemical vapor deposition (PECVD. We focus on the synthetic aspects of carbon hybrid material composed of heteroepitaxially grown graphene on top of a vertical array of carbon nanotubes, called carbon micronymphaea. We characterize the structural features of this unique nanocomposite by uses of electron microscopy and micro-Raman spectroscopy. We observe carbon nanofibers, poorly aligned and well-aligned vertical arrays of CNT sequentially as the growth temperature increases, while we always discover the carbon hybrids, called carbon micronymphaea, at specific cooling rate of 15°C/s, which is optimal for the carbon precipitation from the Ni nanoparticles in this study. We expect one-pot synthesized graphene-on-nanotube hybrid structure poses great potential for applications that demand ultrahigh surface-to-volume ratios with intact graphitic nature and directional electronic and thermal transports.

  13. Carbon Nanotubes by CVD and Applications

    Science.gov (United States)

    Cassell, Alan; Delzeit, Lance; Nguyen, Cattien; Stevens, Ramsey; Han, Jie; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    2001-01-01

    Carbon nanotube (CNT) exhibits extraordinary mechanical and unique electronic properties and offers significant potential for structural, sensor, and nanoelectronics applications. An overview of CNT, growth methods, properties and applications is provided. Single-wall, and multi-wall CNTs have been grown by chemical vapor deposition. Catalyst development and optimization has been accomplished using combinatorial optimization methods. CNT has also been grown from the tips of silicon cantilevers for use in atomic force microscopy.

  14. Quantum transport in carbon nanotubes

    NARCIS (Netherlands)

    Laird, E.A.; Kuemmeth, F.; Steele, G.A.; Grove-Rasmussen, K.; Nygard, J.; Flensberg, K.; Kouwenhoven, L.P.

    2015-01-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This revie

  15. Atomic scale simulation of carbon nanotube nucleation from hydrocarbon precursors.

    Science.gov (United States)

    Khalilov, Umedjon; Bogaerts, Annemie; Neyts, Erik C

    2015-12-22

    Atomic scale simulations of the nucleation and growth of carbon nanotubes is essential for understanding their growth mechanism. In spite of over twenty years of simulation efforts in this area, limited progress has so far been made on addressing the role of the hydrocarbon growth precursor. Here we report on atomic scale simulations of cap nucleation of single-walled carbon nanotubes from hydrocarbon precursors. The presented mechanism emphasizes the important role of hydrogen in the nucleation process, and is discussed in relation to previously presented mechanisms. In particular, the role of hydrogen in the appearance of unstable carbon structures during in situ experimental observations as well as the initial stage of multi-walled carbon nanotube growth is discussed. The results are in good agreement with available experimental and quantum-mechanical results, and provide a basic understanding of the incubation and nucleation stages of hydrocarbon-based CNT growth at the atomic level.

  16. Peel test of spinnable carbon nanotube webs

    Science.gov (United States)

    Khandoker, Noman; Hawkins, Stephen C.; Ibrahim, Raafat; Huynh, Chi P.

    2014-06-01

    This paper presents results of peel tests with spinnable carbon nanotube webs. Peel tests were performed to study the effect of orientation angles on interface energies between nanotubes. In absence of any binding agent the interface energy represents the Van Der Waals energies between the interacting nanotubes. Therefore, the effect of the orientations on Van Der Waals energies between carbon nanotubes is obtained through the peel test. It is shown that the energy for crossed nanotubes at 90° angle is lower than the energy for parallel nanotubes at 0° angle. This experimental observation was validated by hypothetical theoretical calculations.

  17. From carbon nanotubes to carbon atomic chains

    Science.gov (United States)

    Casillas García, Gilberto; Zhang, Weijia; José-Yacamán, Miguel

    2010-10-01

    Carbyne is a linear allotrope of carbon. It is formed by a linear arrangement of carbon atoms with sp-hybridization. We present a reliable and reproducible experiment to obtain these carbon atomic chains using few-layer-graphene (FLG) sheets and a HRTEM. First the FLG sheets were synthesized from worm-like exfoliated graphite and then drop-casted on a lacey-carbon copper grid. Once in the TEM, two holes are opened near each other in a FLG sheet by focusing the electron beam into a small spot. Due to the radiation, the carbon atoms rearrange themselves between the two holes and form carbon fibers. The beam is concentrated on the carbon fibers in order excite the atoms and induce a tension until multi wall carbon nanotube (MWCNT) is formed. As the radiation continues the MWCNT breaks down until there is only a single wall carbon nanotube (SWCNT). Then, when the SWCNT breaks, an atomic carbon chain is formed, lasts for several seconds under the radiation and finally breaks. This demonstrates the stability of this carbon structure.

  18. Attachment of Gold Nanoparticles to Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xi Cheng MA; Ning LUN; Shu Lin WEN

    2005-01-01

    Carbon nanotubes were initially chemically modified with an H2SO4-HNO3 treatment,and subsequently activated with Pd-Sn catalytic nuclei via a one-step activation approach. These activated nanotubes were used as precursors for obtaining gold nanoparticles-attached nanotubes via simple electroless plating. This approach provides an efficient method for attachment of metal nanostructures to carbon nanotubes. Such novel hybrid nanostructures are attractive for many applications.

  19. Pulsed laser deposition of carbon nanotube and polystyrene-carbon nanotube composite thin films

    Science.gov (United States)

    Stramel, A. A.; Gupta, M. C.; Lee, H. R.; Yu, J.; Edwards, W. C.

    2010-12-01

    In this work, we report on the fabrication of carbon nanotube thin films via pulsed laser deposition using a pulsed, diode pumped, Tm:Ho:LuLF laser with 2 μm wavelength. The thin films were deposited on silicon substrates using pure carbon nanotube targets and polystyrene-carbon nanotube composite targets. Raman spectra, scanning electron micrographs, and transmission electron micrographs show that carbon nanotubes are present in the deposited thin films, and that the pulsed laser deposition process causes minimal degradation to the quality of the nanotubes when using pure carbon nanotube targets.

  20. Carbon nanotube materials from hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, A.C.; Bekkedahl, T.A.; Cahill, A.F. [National Renewable Energy Laboratory, Golden, CO (United States)

    1995-09-01

    The lack of convenient and cost-effective hydrogen storage is a major impediment to wide scale use of hydrogen in the United States energy economy. Improvements in the energy densities of hydrogen storage systems, reductions in cost, and increased compatibility with available and forecasted systems are required before viable hydrogen energy use pathways can be established. Carbon-based hydrogen adsorption materials hold particular promise for meeting and exceeding the U.S. Department of Energy hydrogen storage energy density targets for transportation if concurrent increases in hydrogen storage capacity and carbon density can be achieved. These two goals are normally in conflict for conventional porous materials, but may be reconciled by the design and synthesis of new adsorbent materials with tailored pore size distributions and minimal macroporosity. Carbon nanotubes offer the possibility to explore new designs for adsorbents because they can be fabricated with small size distributions, and naturally tend to self-assemble by van der Waals forces. This year we report heats of adsorption for hydrogen on nanotube materials that are 2 and 3 times greater than for hydrogen on activated carbon. The hydrogen which is most strongly bound to these materials remains on the carbon surface to temperatures greater than 285 K. These results suggest that nanocapillary forces are active in stabilizing hydrogen on the surfaces of carbon nanotubes, and that optimization of the adsorbent will lead to effective storage at higher temperatures. In this paper we will also report on our activities which are targeted at understanding and optimizing the nucleation and growth of single wall nanotubes. These experiments were made possible by the development of a unique feedback control circuit which stabilized the plasma-arc during a synthesis run.

  1. Bloch oscillations in carbon nanotubes.

    Science.gov (United States)

    Jódar, Esther; Pérez-Garrido, Antonio; Rojas, Fernando

    2009-05-27

    Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case.

  2. Bloch oscillations in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Jodar, Esther; Perez-Garrido, Antonio [Departamento Fisica Aplicada, Antiguo Hospital de Marina Campus Muralla del Mar, UPCT, Cartagena 30202 Murcia (Spain); Rojas, Fernando [Centro de Nanociencias y Nanotecnologia-UNAM, Apartado Postal 356, Ensenada, Baja California 22800 (Mexico)], E-mail: ejodar@upct.es

    2009-05-27

    Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case. (fast track communication)

  3. Production of single-walled carbon nanotube grids

    Science.gov (United States)

    Hauge, Robert H; Xu, Ya-Qiong; Pheasant, Sean

    2013-12-03

    A method of forming a nanotube grid includes placing a plurality of catalyst nanoparticles on a grid framework, contacting the catalyst nanoparticles with a gas mixture that includes hydrogen and a carbon source in a reaction chamber, forming an activated gas from the gas mixture, heating the grid framework and activated gas, and controlling a growth time to generate a single-wall carbon nanotube array radially about the grid framework. A filter membrane may be produced by this method.

  4. Dispersion fraction enhances cellular growth of carbon nanotube and aluminum oxide reinforced ultrahigh molecular weight polyethylene biocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Anup Kumar; Balani, Kantesh, E-mail: kbalani@iitk.ac.in

    2015-01-01

    Ultrahigh molecular weight polyethylene (UHMWPE) is widely used as bone-replacement material for articulating surfaces due to its excellent wear resistance and low coefficient of friction. But, the wear debris, generated during abrasion between mating surfaces, leads to aseptic loosening of implants. Thus, various reinforcing agents are generally utilized, which may alter the surface and biological properties of UHMWPE. In the current work, the cellular response of compression molded UHMWPE upon reinforcement of bioactive multiwalled carbon nanotubes (MWCNTs) and bioinert aluminum oxide (Al{sub 2}O{sub 3}) is investigated. The phase retention and stability were observed using X-ray diffraction, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The reinforcement of MWCNTs and Al{sub 2}O{sub 3} has shown to alter the wettability (from contact angle of ∼ 88° ± 2° to ∼ 118° ± 4°) and surface energy (from ∼ 23.20 to ∼ 17.75 mN/m) of composites with respect to UHMWPE, without eliciting any adverse effect on cytocompatibility for the L929 mouse fibroblast cell line. Interestingly, the cellular growth of the L929 mouse fibroblast cell line is observed to be dominated by the dispersion fraction of surface free energy (SFE). After 48 h of incubation period, a decrease in metabolic activity of MWCNT–Al{sub 2}O{sub 3} reinforced composites is attributed to apatite formation that reduces the dispersion fraction of surface energy. The mineralized apatite during incubation was confirmed and quantified by energy dispersive spectroscopy and X-ray diffraction respectively. Thus, the dispersion fraction of surface free energy can be engineered to play an important role in achieving enhanced metabolic activity of the MWCNT–Al{sub 2}O{sub 3} reinforced UHMWPE biopolymer composites. - Highlights: • The cellular response of UHMWPE upon MWCNT and Al{sub 2}O{sub 3} reinforcement is highlighted. • Wettability decreases with Al{sub 2}O{sub 3} and

  5. Study of neuron survival on polypyrrole-embedded single-walled carbon nanotube substrates for long-term growth conditions.

    Science.gov (United States)

    Hernández-Ferrer, Javier; Pérez-Bruzón, Rodolfo N; Azanza, María J; González, Mónica; Del Moral, Raquel; Ansón-Casaos, Alejandro; de la Fuente, Jesús M; Marijuan, Pedro C; Martínez, M Teresa

    2014-12-01

    Cultures of primary embryonic rat brain hippocampus neurons with supporting glia cells were carried out on different substrates containing polypyrrole (PPy) and/or single-walled carbon nanotubes (SWCNTs). Neuron adhesion, neurites and dendrites branching elongation, and development of neuron networks on substrates were followed by phase-contrast optical microscopy and quantified to state cell survival and proliferation. Suspensions of as-grown and purified SWCNTs were sprayed on a glass coverslips and PPy/SWCNTs were deposited by potentiodynamic electrochemical deposition. Cell neurotoxicity revealed by neuron death was very high for purified SWCNTs substrates in good agreement with [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) test showing lower viability on SWCNTs containing substrates compared with PPy-substrates and control samples probably due to the metal content and the carboxylic groups introduced during the purification. It is interesting to highlight that neurons grown on PPy-substrates adhere developing neurites and branching dendrites earlier even than on control cultures. On subsequent days the neurons are able to adapt to nanotube substrates developing neuron networks for 14-day cultures with similar patterns of complexity for control, PPy and PPy/SWCNT substrates. PPy/SWCNT substrates show a lower impedance value at frequencies under 1 Hz. We have come to the conclusion that glia cells and PPy added to the culture medium and substrates respectively, improve in some degree nanotube biocompatibility, cell adhesion and hence cell viability.

  6. Carbon nanotube diameter selection by pretreatment of metal catalysts on surfaces

    Science.gov (United States)

    Hauge, Robert H.; Xu, Ya-Qiong; Shan, Hongwei; Nicholas, Nolan Walker; Kim, Myung Jong; Schmidt, Howard K.; Kittrell, W. Carter

    2012-02-28

    A new and useful nanotube growth substrate conditioning processes is herein disclosed that allows the growth of vertical arrays of carbon nanotubes where the average diameter of the nanotubes can be selected and/or controlled as compared to the prior art.

  7. Carbon Nanotubes Filled with Ferromagnetic Materials

    Directory of Open Access Journals (Sweden)

    Albrecht Leonhardt

    2010-08-01

    Full Text Available Carbon nanotubes (CNT filled with ferromagnetic metals like iron, cobalt or nickel are new and very interesting nanostructured materials with a number of unique properties. In this paper we give an overview about different chemical vapor deposition (CVD methods for their synthesis and discuss the influence of selected growth parameters. In addition we evaluate possible growth mechanisms involved in their formation. Moreover we show their identified structural and magnetic properties. On the basis of these properties we present different application possibilities. Some selected examples reveal the high potential of these materials in the field of medicine and nanotechnology.

  8. Pressure-Induced Interlinking of Carbon Nanotubes

    OpenAIRE

    Yildirim, T.; Gulseren, O.; Kilic, C.; Ciraci, S.

    2000-01-01

    We predict new forms of carbon consisting of one and two dimensional networks of interlinked single wall carbon nanotubes, some of which are energetically more stable than van der Waals packing of the nanotubes on a hexagonal lattice. These interlinked nanotubes are further transformed with higher applied external pressures to more dense and complicated stable structures, in which curvature-induced carbon sp$^{3}$ re-hybridizations are formed. We also discuss the energetics of the bond format...

  9. Different Technical Applications of Carbon Nanotubes

    OpenAIRE

    Abdalla, S; Al-Marzouki, F.; Ahmed A. Al-Ghamdi; Abdel-Daiem, A.

    2015-01-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc....

  10. Faster and Smaller with Carbon Nanotubes?

    OpenAIRE

    Seidel, Robert V.; Graham, Andrew P.; Duesberg, Georg S.; Liebau, Maik; Unger, Eugen; Kreupl, Franz; Hoenlein, Wolfgang

    2004-01-01

    Carbon Nanotubes seem to be one of the most promising candidates for nanoelectronic devices beyond presumable scaling limits of silicon and compound semiconductors and independent from lithographic limitations. Discovered only about a decade ago, there has been a tremendous advance in the field of carbon nanotubes. Their exciting properties, especially with respect to electronic applications, and their fabrication methods will be discussed. A variety of Carbon Nanotube...

  11. Carbon Nanotubes and Related Structures

    Directory of Open Access Journals (Sweden)

    Kingsuk Mukhopadhyay

    2008-07-01

    Full Text Available Carbon nanotubes have attracted the fancy of many scientists world wide. The small dimensions,strength, and the remarkable physical properties of these structures make them a unique material with a whole range of promising applications. In this review, the structural aspects, the advantages and disadvantages of different for their procedures synthesis, the qualitative and quantitative estimation of carbon nanotubes by different analytical techniques, the present status on their applications as well as the current challenges faced in the application field, national, in particular DRDO, DMSRDE status, and interest in this field, have been discussed.Defence Science Journal, 2008, 58(4, pp.437-450, DOI:http://dx.doi.org/10.14429/dsj.58.1666

  12. Ballistic Fracturing of Carbon Nanotubes.

    Science.gov (United States)

    Ozden, Sehmus; Machado, Leonardo D; Tiwary, ChandraSekhar; Autreto, Pedro A S; Vajtai, Robert; Barrera, Enrique V; Galvao, Douglas S; Ajayan, Pulickel M

    2016-09-21

    Advanced materials with multifunctional capabilities and high resistance to hypervelocity impact are of great interest to the designers of aerospace structures. Carbon nanotubes (CNTs) with their lightweight and high strength properties are alternative to metals and/or metallic alloys conventionally used in aerospace applications. Here we report a detailed study on the ballistic fracturing of CNTs for different velocity ranges. Our results show that the highly energetic impacts cause bond breakage and carbon atom rehybridizations, and sometimes extensive structural reconstructions were also observed. Experimental observations show the formation of nanoribbons, nanodiamonds, and covalently interconnected nanostructures, depending on impact conditions. Fully atomistic reactive molecular dynamics simulations were also carried out in order to gain further insights into the mechanism behind the transformation of CNTs. The simulations show that the velocity and relative orientation of the multiple colliding nanotubes are critical to determine the impact outcome.

  13. Carbon Nanotubes: Molecular Electronic Components

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

    The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

  14. Torsional Carbon Nanotube Artificial Muscles

    Science.gov (United States)

    Foroughi, Javad; Spinks, Geoffrey M.; Wallace, Gordon G.; Oh, Jiyoung; Kozlov, Mikhail E.; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D. W.; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H.

    2011-10-01

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  15. A Thermal Model for Carbon Nanotube Interconnects

    Science.gov (United States)

    Mohsin, Kaji Muhammad; Srivastava, Ashok; Sharma, Ashwani K.; Mayberry, Clay

    2013-01-01

    In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI) interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT) interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.

  16. OPPORTUNITIES OF BIOMEDICAL USE OF CARBON NANOTUBES

    Directory of Open Access Journals (Sweden)

    I. V. Mitrofanova

    2014-01-01

    Full Text Available Nanomaterials  –  materials,  whouse  structure  elements  has  proportions  doesn’t  exceed  100  nm.  In superdispersed state matter acquire new properties. In the last decade, carbon nanotubes become the most popular nanomaterials, that cause attention of representatives of various scientific field. The сarbon nanotubes offer new opportunities for biological and medical applications: imaging at the molecular, cellular and tissue levels, biosensors and electrodes based on carbon nanotubes, target delivery of various substances, radiation and photothermal therapy. The most promising of carbon nanotubes in the context of biomedical applications is their ability to penetrate the various tissues of the body and carry large doses of agents, providing diagnostic and therapeutic effects. Functionalized nanotubes are biodegradable. Other current direction of using carbon nanotubes in medicine and biology is to visualize objects on the molecular, cellular and tissue level. Associated with carbon nanotubes contrasting substances improve the visualization of cells and tissues, which can detected new patterns of development of the pathological process. Due to the vagueness of the question of biocompatibility and cytotoxicity of carbon nanotubes possibility of their practical application is hampered. Before the introduction of carbon nanotubes into practical health care is necessary to provide all the possible consequences of using nanotubes. High rates of properties and development of new nanostructures based on carbon nanotubes in the near future will lead to new advances related to the application and development of new parameters that will determine their properties and effects. In these review attention is paid to the structure, physico-chemical properties of nanotubes, their functionalization, pharmacokinetics and pharmacodynamics and all aspects of using of carbon nanotubes.

  17. In situ Diagnostics During Carbon Nanotube Production by Laser Ablation

    Science.gov (United States)

    Arepalli, Sivaram

    1999-01-01

    The preliminary results of spectral analysis of the reaction zone during the carbon nanotube production by laser ablation method indicate synergetic dependence on dual laser setup. The emission spectra recorded from different regions of the laser ablated plume at different delay times from the laser pulses are used to map the temperatures of C2 and C3. These are compared with Laser Induced Fluorescence (LIF) spectra also obtained during production to model the growth mechanism of carbon nanotubes. Experiments conducted to correlate the spectral features with nanotube yields as a function of different production parameters will be discussed.

  18. Real-Time Observation of Cell and Carbon Nanotube Interactions

    Science.gov (United States)

    Chen, Michelle; Broman, Melanie; Mathews, Claire; McPherson, Eric

    2014-03-01

    Carbon nanotubes have been widely researched for disease diagnosis and drug delivery applications. However, its impact on biological systems is yet to be sufficiently understood. We studied optical imaging of Chinese hamster ovarian (CHO) cells exposed to various carbon nanotubes concentrations at various time points. The cell stress due to carbon nanotubes exposure is accessed via morphological changes of the CHO cells. Data showed that cell death increases with increasing carbon nanotube concentration and time exposure. To continuously view such changes of any one individual cell, we constructed an optically transparent miniaturized incubator that fits on a microscope stage. This specific incubator is able to maintain desirable temperature, humidity, and CO2 concentration to allow proper cell growth. Such incubator can be used to track real-time interactions of any cells and nanomaterials for future data collection.

  19. LDRD final report on carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Cahill, P.A.; Rand, P.B.

    1997-04-01

    Carbon nanotubes and their composites were examined using computational and experimental techniques in order to modify the mechanical and electrical properties of resins. Single walled nanotubes were the focus of the first year effort; however, sufficient quantities of high purity single walled nanotubes could not be obtained for mechanical property investigations. The unusually high electrical conductivity of composites loaded with <1% of multiwalled nanotubes is useful, and is the focus of continuing, externally funded, research.

  20. Degradation and healing mechanisms of carbon fibers during the catalytic growth of carbon nanotubes on their surfaces.

    Science.gov (United States)

    Kim, Kyoung Ju; Yu, Woong-Ryeol; Youk, Ji Ho; Lee, Jinyong

    2012-04-01

    This study reports on the main cause of the reduced tensile strength of carbon fibers (CFs) by investigating the microstructural changes in the CFs that are undergoing mainly two processes: catalyst nanoparticle formation and chemical vapor deposition (CVD). Interestingly, the two processes oppositely influenced the tensile strength of the CFs: the former negatively and the latter positively. The catalysts coating and nanoparticle formation degraded the CF surface by inducing amorphous carbons and severing graphitic layers, while those defects were healed by both the injected carbons and interfaced CNTs during the CVD process. The revealed degradation and healing mechanisms can serve as a fundamental engineering basis for exploring optimized processes in the manufacturing of hierarchical reinforcements without sacrificing the tensile strength of the substrate CFs.

  1. Engineering carbon nanotubes and nanotube circuits using electrical breakdown.

    Science.gov (United States)

    Collins, P G; Arnold, M S; Avouris, P

    2001-04-27

    Carbon nanotubes display either metallic or semiconducting properties. Both large, multiwalled nanotubes (MWNTs), with many concentric carbon shells, and bundles or "ropes" of aligned single-walled nanotubes (SWNTs), are complex composite conductors that incorporate many weakly coupled nanotubes that each have a different electronic structure. Here we demonstrate a simple and reliable method for selectively removing single carbon shells from MWNTs and SWNT ropes to tailor the properties of these composite nanotubes. We can remove shells of MWNTs stepwise and individually characterize the different shells. By choosing among the shells, we can convert a MWNT into either a metallic or a semiconducting conductor, as well as directly address the issue of multiple-shell transport. With SWNT ropes, similar selectivity allows us to generate entire arrays of nanoscale field-effect transistors based solely on the fraction of semiconducting SWNTs.

  2. Green backlighting for TV liquid crystal display using carbon nanotubes

    Science.gov (United States)

    Delepierre, Gabriel; Mahfouz, Rami; Cadete Santos Aires, Francisco J.; Dijon, Jean

    2010-08-01

    A methodology to evaluate the emission characteristics of carbon nanotube layers in the context of liquid crystal display backlighting has been elaborated. Carbon nanotube layers with emission characteristics compatible with backlighting have been demonstrated for growth temperature as low as 400 °C, thanks to the use of plasma pretreatment before growth. This very low growth temperature allows to use soda lime glass for the backlight unit and thus to expect very low cost and very low power consumption devices with this technology.

  3. Plasticity and Kinky Chemistry of Carbon Nanotubes

    Science.gov (United States)

    Srivastava, Deepak; Dzegilenko, Fedor

    2000-01-01

    Since their discovery in 1991, carbon nanotubes have been the subject of intense research interest based on early predictions of their unique mechanical, electronic, and chemical properties. Materials with the predicted unique properties of carbon nanotubes are of great interest for use in future generations of aerospace vehicles. For their structural properties, carbon nanotubes could be used as reinforcing fibers in ultralight multifunctional composites. For their electronic properties, carbon nanotubes offer the potential of very high-speed, low-power computing elements, high-density data storage, and unique sensors. In a continuing effort to model and predict the properties of carbon nanotubes, Ames accomplished three significant results during FY99. First, accurate values of the nanomechanics and plasticity of carbon nanotubes based on quantum molecular dynamics simulations were computed. Second, the concept of mechanical deformation catalyzed-kinky-chemistry as a means to control local chemistry of nanotubes was discovered. Third, the ease of nano-indentation of silicon surfaces with carbon nanotubes was established. The elastic response and plastic failure mechanisms of single-wall nanotubes were investigated by means of quantum molecular dynamics simulations.

  4. Dielectrophoretic assembly of carbon nanotube devices

    DEFF Research Database (Denmark)

    Dimaki, Maria

    The purpose of this project has been to assemble single-walled carbon nanotubes on electrodes at the tip of a biocompatible cantilever and use these for chemical species sensing in air and liquid, for example in order to measure the local activity from ion channels in the cell membrane....... The electrical resistance of carbon nanotubes has been shown to be extremely sensitive to gas molecules. Dielectrophoresis is a method capable of quickly attracting nanotubes on microelectrodes by using an electric field, thus enabling nanotube integration in microsystems. Dielectrophoresis offers also...... the potential of distinguishing between nanotubes of different electrical properties, which is very important for the optimisation of the properties of the carbon nanotube sensors. Various cantilever and planar structures were designed, fabricated and tested both with multi-walled and single-walled carbon...

  5. Sorting carbon nanotubes for electronics.

    Science.gov (United States)

    Martel, Richard

    2008-11-25

    Because of their unique structure and composition, single-wall carbon nanotubes (SWNTs) are at the interface between molecules and crystalline solids. They also present properties that are ideal for making lightweight, inexpensive, and flexible electronics. The raw material is composed of a heterogeneous mixture of SWNTs that differ in helicity and diameter and, therefore, requires purification and separation. In a series of groundbreaking experiments, a robust process serving this purpose was developed based on SWNTs encapsulated in surfactants and water. Ultracentrifugation in a density gradient combined with surfactant mixtures provided buoyant density differences, enabling enrichment for both diameter and electronic properties. A new paper in this issue explores further the process through the hydrodynamic properties of SWNT-surfactant complexes. The study reveals that we have just begun to uncover the dynamics and properties of nanotube-surfactant interactions and highlights the potential that could be gained from a better understanding of their chemistry. The time scale of integration of carbon nanotubes into electronics applications remains unclear, but the recent developments in sorting out SWNTs paves the way for improving on the properties of network-based SWNTs.

  6. Synthesis of carbon nanotubes by catalytic pyrolysis method with Feitknecht compound as precursor of NiZnAl catalyst

    Institute of Scientific and Technical Information of China (English)

    Yan Xiaoqi; Liu Quanrun; Zhang Songlin; Zhang Kun; Chen Jiuling; Li Yongdan

    2004-01-01

    Carbon nanotubes are synthesized by catalytic pyrolysis method with a kind of new type catalyst--nickel-zinc-alumina catalyst prepared from Feitknecht compound. Tubular carbon nanotubes, bamboo-shaped carbon naotubes, herringbone carbon nanotubues and branched carbon nanotubes are all found formed at moderate temperature. It is important for the formation of quasi-liquid state of the metal nanoparticles at the tip of carbon naotubes during the growth of carbon nanotubes to lead to different kinds of carbon nanotubes. It is likely that the addition of zinc make the activity of nickel catalyst after calcinations and reduction changed strangely.

  7. Study of Carbon Nanotube-Substrate Interaction

    Directory of Open Access Journals (Sweden)

    Jaqueline S. Soares

    2012-01-01

    Full Text Available Environmental effects are very important in nanoscience and nanotechnology. This work reviews the importance of the substrate in single-wall carbon nanotube properties. Contact with a substrate can modify the nanotube properties, and such interactions have been broadly studied as either a negative aspect or a solution for developing carbon nanotube-based nanotechnologies. This paper discusses both theoretical and experimental studies where the interaction between the carbon nanotubes and the substrate affects the structural, electronic, and vibrational properties of the tubes.

  8. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  9. A Tunable Carbon Nanotube Oscillator

    Science.gov (United States)

    Sazonova, Vera

    2005-03-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. Carbon nanotubes (NT) are perhaps the ultimate material for realizing a NEMS device as they are the stiffest material known, have low density, ultrasmall cross sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus is able to sense its own motion. Here, we report the electrical actuation and detection of the guitar-string oscillation modes of doubly-clamped NT oscillators. We observed resonance frequencies in the 5MHz to 150MHz range with quality factors in the 50 to 100 range. We showed that the resonance frequencies can be widely tuned by a gate voltage. We also report on the temperature dependence of the quality factor and present a discussion of possible loss mechanisms.

  10. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.

    2014-04-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  11. Mapping the transition from catalyst-pool to bamboo-like growth-mechanism in vertically-aligned free-standing films of carbon nanotubes filled with Fe3C: The key role of water

    Science.gov (United States)

    Boi, Filippo S.; Wang, Shanling; He, Yi

    2016-08-01

    The control of carbon nanotube growth has challenged researchers for more than a decade due to the complex parameters-control necessary in the commonly used CVD approaches. Here we show that a direct transition from the catalyst-pool growth mechanism characterized by graphene-caps in the direction of growth to a bamboo-shaped mechanism characterized by the repetition of periodic elongated graphitic compartments is present when controlled quantities of water are added to ferrocene/dichlorobenzene. Our results suggest that water-addition allows enhancing the level of stress accumulated under the graphitic nanotubes-cap.

  12. Hydrogen Storage in Carbon Nanotubes

    Science.gov (United States)

    Gilbert, Joseph; Gilbert, Matthew; Naab, Fabian; Savage, Lauren; Holland, Wayne; Duggan, Jerome; McDaniel, Floyd

    2004-10-01

    Hydrogen as a fuel source is an attractive, relatively clean alternative to fossil fuels. However, a major limitation in its use for the application of automobiles has been the requirement for an efficient hydrogen storage medium. Current hydrogen storage systems are: physical storage in high pressure tanks, metal hydride, and gas-on-solid absorption. However, these methods do not fulfill the Department of Energy's targeted requirements for a usable hydrogen storage capacity of 6.5 wt.%, operation near ambient temperature and pressure, quick extraction and refueling, reliability and reusability.Reports showing high capacity hydrogen storage in single-walled carbon nanotubes originally prompted great excitement in the field, but further research has shown conflicting results. Results for carbon nanostructures have ranged from less than 1 wt.% to 70 wt.%. The wide range of adsorption found in previous experiments results from the difficulty in measuring hydrogen in objects just nanometers in size. Most previous experiments relied on weight analysis and residual gas analysis to determine the amount of hydrogen being adsorbed by the CNTs. These differing results encouraged us to perform our own analysis on single-walled (SWNTs), double-walled (DWNTs), and multi-walled carbon nanotubes (MWNTs), as well as carbon fiber. We chose to utilize direct measurement of hydrogen in the materials using elastic recoil detection analysis (ERDA). This work was supported by the National Science Foundation's Research Experience for Undergraduates and the University of North Texas.

  13. Optimization of growth temperature of multi-walled carbon nanotubes synthesized by spray pyrolysis method and application for arsenic removal

    Directory of Open Access Journals (Sweden)

    S. Mageswari

    2014-12-01

    Full Text Available Multi-walled carbon nanotubes have been synthesized at different temperatures ranging from 550 °C to 750 °C on silica supported Fe-Co catalyst by spray pyrolysis method using Citrus limonum oil under nitrogen atmosphere. The as-grown MWNTs were characterized by scanning electron microscope (SEM, high resolution transmission electron microscope (HRTEM, X-ray diffraction analysis (XRD and Raman spectral studies. The HRTEM and Raman spectroscopic studies confirmed the evolution of MWNTs with the outer diameter between 25 and 38 nm. The possibility of use of as-grown MWNTs as an adsorbent for removal of As (V ions from drinking water was studied. Adsorption isotherm data were interpreted by the Langmuir and Freundlich equations. Kinetic data were studied using Elovich, pseudo-first order and pseudo-second order equations in order to elucidate the reaction mechanism.

  14. Glucose oxidase immobilization onto carbon nanotube networking

    CERN Document Server

    Karachevtsev, V A; Zarudnev, E S; Karachevtsev, M V; Leontiev, V S; Linnik, A S; Lytvyn, O S; Plokhotnichenko, A M; Stepanian, S G

    2012-01-01

    When elaborating the biosensor based on single-walled carbon nanotubes (SWNTs), it is necessary to solve such an important problem as the immobilization of a target biomolecule on the nanotube surface. In this work, the enzyme (glucose oxidase (GOX)) was immobilized on the surface of a nanotube network, which was created by the deposition of nanotubes from their solution in 1,2-dichlorobenzene by the spray method. 1-Pyrenebutanoic acid succinimide ester (PSE) was used to form the molecular interface, the bifunctional molecule of which provides the covalent binding with the enzyme shell, and its other part (pyrene) is adsorbed onto the nanotube surface. First, the usage of such a molecular interface leaves out the direct adsorption of the enzyme (in this case, its activity decreases) onto the nanotube surface, and, second, it ensures the enzyme localization near the nanotube. The comparison of the resonance Raman (RR) spectrum of pristine nanotubes with their spectrum in the PSE environment evidences the creat...

  15. Polymer Self-assembly on Carbon Nanotubes

    Science.gov (United States)

    Giulianini, Michele; Motta, Nunzio

    This chapter analyses the poly(3-hexylthiophene) self-assembly on carbon nanotubes and the interaction between the two materials forming a new hybrid nanostructure. The chapter starts with a review of the several studies investigating polymers and biomolecules self-assembled on nanotubes. Then conducting polymers and polythiophenes are briefly introduced. Accordingly, carbon nanotube structure and properties are reported in Sect. 3. The experimental section starts with the bulk characterisation of polymer thin films with the inclusion of uniformly distributed carbon nanotubes. By using volume film analysis techniques (AFM, TEM, UV-Vis and Raman), we show how the polymer's higher degree of order is a direct consequence of interaction with carbon nanotubes. Nevertheless, it is through the use of nanoscale analysis and molecular dynamic simulations that the self-assembly of the polymer on the nanotube surface can be clearly evidenced and characterised. In Sect. 6, the effect of the carbon templating structure on the P3HT organisation on the surface is investigated, showing the chirality-driven polymer assembly on the carbon nanotube surface. The interaction between P3HT and CNTs brings also to charge transfer, with the modification of physical properties for both species. In particular, the alteration of the polymer electronic properties and the modification of the nanotube mechanical structure are a direct consequence of the P3HT π-π stacking on the nanotube surface. Finally, some considerations based on molecular dynamics studies are reported in order to confirm and support the experimental results discussed.

  16. Suspended carbon nanotubes coupled to superconducting circuits

    NARCIS (Netherlands)

    Schneider, B.H.

    2014-01-01

    Carbon nanotubes are unique candidates to study quantum mechanical properties of a nanomechanical resonator. However to access this quantum regime, present detectors are not yet sensitive enough. In this thesis we couple a carbon nanotube CNT mechanical resonator to a superconducting circuit which i

  17. Carbon Nanotubes – Interactions with Biological Systems

    OpenAIRE

    Reis, Joana; Capela-Silva, Fernando; Potes, José; Fonseca, Alexandra; Oliveira, Mónica; Kanagaraj, Subramani; Marques, António Torres

    2011-01-01

    his book chapter discusses the prospective biomedical applications of carbon nanotubes based materials, the impact of carbon nanotubes properties in the interaction with biological systems. Protein adsorption, impact on cell viability and cytokine production are explored. Potential respiratory and dermal toxicity are reviewed, as the difficulties on studying the biological response. In face of recent studies, special attention is drawn upon promising orthopaedic use.

  18. Multiscale Simulations of Carbon Nanotubes and Liquids

    Science.gov (United States)

    Koumoutsakos, Petros

    2005-11-01

    We present molecular dynamics and hybrid continuum/atomistic simulations of carbon nanotubes in liquid environments with an emphasis on aqueous solutions. We emphasize computational issues such as interaction potentials and coupling techniques and their influence on the simulated physics. We present results from simulations of water flows inside and outside doped and pure carbon nanotubes and discuss their implications for experimental studies.

  19. Highly efficient metal-free growth of nitrogen-doped single-walled carbon nanotubes on plasma-etched substrates for oxygen reduction.

    Science.gov (United States)

    Yu, Dingshan; Zhang, Qiang; Dai, Liming

    2010-11-03

    We have for the first time developed a simple plasma-etching technology to effectively generate metal-free particle catalysts for efficient metal-free growth of undoped and/or nitrogen-doped single-walled carbon nanotubes (CNTs). Compared with undoped CNTs, the newly produced metal-free nitrogen-containing CNTs were demonstrated to show relatively good electrocatalytic activity and long-term stability toward oxygen reduction reaction (ORR) in an acidic medium. Owing to the highly generic nature of the plasma etching technique, the methodology developed in this study can be applied to many other substrates for efficient growth of metal-free CNTs for various applications, ranging from energy related to electronic and to biomedical systems.

  20. Frontiers of graphene and carbon nanotubes devices and applications

    CERN Document Server

    2015-01-01

    This book focuses on carbon nanotubes and graphene as representatives of nano-carbon materials, and describes the growth of new technology and applications of new devices. As new devices and as new materials, nano-carbon materials are expected to be world pioneers that could not have been realized with conventional semiconductor materials, and as those that extend the limits of conventional semiconductor performance. This book introduces the latest achievements of nano-carbon devices, processes, and technology growth. It is anticipated that these studies will also be pioneers in the development of future research of nano-carbon devices and materials. This book consists of 18 chapters. Chapters 1 to 8 describe new device applications and new growth methods of graphene, and Chapters 9 to 18, those of carbon nanotubes. It is expected that by increasing the advantages and overcoming the weak points of nanocarbon materials, a new world that cannot be achieved with conventional materials will be greatly expanded. W...

  1. Development of supercapacitors based on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Block-type electrodes made of carbon nanotubes were fabricated by different processes. The volumetric specific capacitance based on such electrodes reached 107 F/cm3, which proves carbon nanotubes to be ideal candidate materials for supercapacitors. The composite electrodes consisting of carbon nanotubes and RuO2.xH2O were developed by the deposition of RuO2 on the surface of carbon nanotubes. Supercapacitors based on the composite electrodes show much higher specific capacitance than those based on pure carbon nanotube ones. A specific capacitance of 600 F/g can be achieved when the weight percent of RuO2.xH2O in the composite electrodes reaches 75%. In addition, supercapacitors based on the composite electrodes show both high energy density and high power density characteristics.

  2. Development of supercapacitors based on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    马仁志; 魏秉庆; 徐才录; 梁吉; 吴德海

    2000-01-01

    Block-type electrodes made of carbon nanotubes were fabricated by different processes. The volumetric specific capacitance based on such electrodes reached 107 F/cm3, which proves carbon nanotubes to be ideal candidate materials for supercapacitors. The composite electrodes consisting of carbon nanotubes and RuO2 ·xH2O were developed by the deposition of RuO2 on the surface of carbon nanotubes. Supercapacitors based on the composite electrodes show much higher specific capacitance than those based on pure carbon nanotube ones. A specific capacitance of 600 F/g can be achieved when the weight percent of RuO2· xH2O in the composite electrodes reaches 75% . In addition , supercapacitors based on the composite electrodes show both high energy density and high power density characteristics.

  3. Growing carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Yoshinori Ando

    2004-10-01

    Full Text Available The discovery of ‘fullerenes’ added a new dimension to the knowledge of carbon science1; and the subsequent discovery of ‘carbon nanotubes’ (CNTs, the elongated fullerene added a new dimension to the knowledge of technology2;. Today, ‘nanotechnology’ is a hot topic attracting scientists, industrialists, journalists, governments, and even the general public. Nanotechnology is the creation of functional materials, devices, and systems through control of matter on the nanometer scale and the exploitation of novel phenomena and properties of matter (physical, chemical, biological, electrical, etc. at that length scale. CNTs are supposed to be a key component of nanotechnology. Almost every week a new potential application of CNTs is identified, stimulating scientists to peep into this tiny tube with ever increasing curiosity.

  4. Improved synthesis of carbon nanotubes with junctions and of single-walled carbon nanotubes

    Indian Academy of Sciences (India)

    F L Deepak; A Govindaraj; C N R Rao

    2006-01-01

    Pyrolysis of thiophene over nickel nanoparticles dispersed on silica is shown to yield Yjunction carbon nanotubes with smaller diameters than those obtained by the pyrolysis of organometallicthiophene mixtures. In the presence of water vapour, the pyrolysis of organometallic-hydrocarbon mixtures yields single-walled nanotubes, as well as relatively narrow-diameter carbon nanotubes with Y-junctions. Pyrolysis of organometallic-hydrocarbon mixtures, in the absence of water vapour, only gives nanotubes with T- and Y-junctions.

  5. Coated carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  6. Carbon Nanotube Microarrays Grown on Nanoflake Substrates

    Science.gov (United States)

    Schmidt, Howard K.; Hauge, Robert H.; Pint, Cary; Pheasant, Sean

    2013-01-01

    This innovation consists of a new composition of matter where single-walled carbon nanotubes (SWNTs) are grown in aligned arrays from nanostructured flakes that are coated in Fe catalyst. This method of growth of aligned SWNTs, which can yield well over 400 percent SWNT mass per unit substrate mass, exceeds current yields for entangled SWNT growth. In addition, processing can be performed with minimal wet etching treatments, leaving aligned SWNTs with superior properties over those that exist in entangled mats. The alignment of the nanotubes is similar to that achieved in vertically aligned nanotubes, which are called "carpets. " Because these flakes are grown in a state where they are airborne in a reactor, these flakes, after growing SWNTs, are termed "flying carpets. " These flakes are created in a roll-to-roll evaporator system, where three subsequent evaporations are performed on a 100-ft (approx. =30-m) roll of Mylar. The first layer is composed of a water-soluble "release layer, " which can be a material such as NaCl. After depositing NaCl, the second layer involves 40 nm of supporting layer material . either Al2O3 or MgO. The thickness of the layer can be tuned to synthesize flakes that are larger or smaller than those obtained with a 40-nm deposition. Finally, the third layer consists of a thin Fe catalyst layer with a thickness of 0.5 nm. The thickness of this layer ultimately determines the diameter of SWNT growth, and a layer that is too thick will result in the growth of multiwalled carbon nanotubes instead of single-wall nanotubes. However, between a thickness of 0.5 nm to 1 nm, single-walled carbon nanotubes are known to be the primary constituent. After this three-layer deposition process, the Mylar is rolled through a bath of water, which allows catalyst-coated flakes to detach from the Mylar. The flakes are then collected and dried. The method described here for making such flakes is analogous to that which is used to make birefringent ink that is

  7. Purification of carbon nanotube by wet oxidation; Shisshiki sanka ni yoru carbon nanotube no seisei

    Energy Technology Data Exchange (ETDEWEB)

    Morishita, K.; Takarada, T. [Gunma University, Gunma (Japan)

    1997-07-10

    In order to efficiently recover carbon nanotubes, the purification method by wet oxidation with orthoperiodic acid and perchloric acid is investigated. The reactivity of the carbonaceous material toward the acids depends on the type of carbon. Carbon nanotubes are selectively recovered under the mild oxidation conditions. The degree of purification depends on the concentration of orthoperiodic acid. It is suggested that wet oxidation is an effective method for purification of carbon nanotubes. 17 refs., 6 figs.

  8. Carbon nanotubes on carbon fibers: Synthesis, structures and properties

    Science.gov (United States)

    Zhang, Qiuhong

    The interface between carbon fibers (CFs) and the resin matrix in traditional high performance composites is characterized by a large discontinuity in mechanical, electrical, and thermal properties which can cause inefficient energy transfer. Due to the exceptional properties of carbon nanotubes (CNTs), their growth at the surface of carbon fibers is a promising approach to controlling interfacial interactions and achieving the enhanced bulk properties. However, the reactive conditions used to grow carbon nanotubes also have the potential to introduce defects that can degrade the mechanical properties of the carbon fiber (CF) substrate. In this study, using thermal chemical vapor deposition (CVD) method, high density multi-wall carbon nanotubes have been successfully synthesized directly on PAN-based CF surface without significantly compromising tensile properties. The influence of CVD growth conditions on the single CF tensile properties and carbon nanotube (CNT) morphology was investigated. The experimental results revealed that under high temperature growth conditions, the tensile strength of CF was greatly decreased at the beginning of CNT growth process with the largest decrease observed for sized CFs. However, the tensile strength of unsized CFs with CNT was approximately the same as the initial CF at lower growth temperature. The interfacial shear strength of CNT coated CF (CNT/CF) in epoxy was studied by means of the single-fiber fragmentation test. Results of the test indicate an improvement in interfacial shear strength with the addition of a CNT coating. This improvement can most likely be attributed to an increase in the interphase yield strength as well as an improvement in interfacial adhesion due to the presence of the nanotubes. CNT/CF also offers promise as stress and strain sensors in CF reinforced composite materials. This study investigates fundamental mechanical and electrical properties of CNT/CF using nanoindentation method by designed

  9. Mechanical behavior of ultralong multiwalled carbon nanotube mats

    Science.gov (United States)

    Deck, Christian P.; Flowers, Jason; McKee, Gregg S. B.; Vecchio, Kenneth

    2007-01-01

    Carbon nanotubes (CNTs) have been a subject of great interest partially due to their potential for exceptional material properties. Improvements in synthesis methods have facilitated the production of ultralong CNT mats, with lengths in the millimeter range. The increased length of these ultralong mats has, in return, opened the way to greater flexibility to probe their mechanical response. In this work, mats of dense, well-aligned, multiwalled carbon nanotubes were grown with a vapor-phase chemical vapor deposition technique using ferrocene and benzene as reactants, and subsequently tested in both tension and compression using two methods, in a thermomechanical analyzer and in situ inside a scanning electron microscope. In compression, measured stiffness was very low, due to buckling of the nanotubes. In tension, the nanotube mats behaved considerably stiffer; however, they were still more compliant than expected for nanotubes (˜1TPa). Analysis of both the growth method used and the nanotube mat fracture surface suggests that the mats grown in this method are not composed of continuous nanotubes and their strengths actually closely match those of woven nanotube yarns and ropes.

  10. Catalysts for Efficient Production of Carbon Nanotubes

    Science.gov (United States)

    Sun, Ted X.; Dong, Yi

    2009-01-01

    Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

  11. Mechanisms of Carbon Nanotube Production by Laser Ablation Process

    Science.gov (United States)

    Scott, Carl D.; Arepalli, Sivaram; Nikolaev, Pavel; Smalley, Richard E.; Nocholson, Leonard S. (Technical Monitor)

    2000-01-01

    We will present possible mechanisms for nanotube production by laser oven process. Spectral emission of excited species during laser ablation of a composite graphite target is compared with that of laser irradiated C60 vapor. The similarities in the transient and spectral data suggest that fullerenes are intermediate precursors for nanotube formation. The confinement of the ablation products by means of a 25-mm diameter tube placed upstream of the target seems to improve the production and purity of nanotubes. Repeated laser pulses vaporize the amorphous/graphitic carbon and possibly catalyst particles, and dissociate fullerenes yielding additional feedstock for SWNT growth.

  12. A one-step single source route to carbon nanotubes

    Indian Academy of Sciences (India)

    Tao Cheng; Zhiyong Fang; Guifu Zou; Qixiu Hu; Biao Hu; Xiaozhi Yang; Youjin Zhang

    2006-12-01

    Carbon nanotubes (CNTs) have been synthesized via directly pyrolyzing ferrocene in the autoclave. The nanotubes with several micrometers in length have outer and inner diameters in the range of 40–100 nm and 20–40 nm, respectively. An yield of ∼70% of CNTs can be obtained without any accessorial solvents and catalysts. Experimental results showed that a temperature higher than 600°C in conjunction with proper pressure was favourable for achievement of the nanotubes. The growth mechanism of CNTs was also discussed.

  13. Functionalized carbon nanotubes: biomedical applications

    Directory of Open Access Journals (Sweden)

    Vardharajula S

    2012-10-01

    Full Text Available Sandhya Vardharajula,1 Sk Z Ali,2 Pooja M Tiwari,1 Erdal Eroğlu,1 Komal Vig,1 Vida A Dennis,1 Shree R Singh11Center for NanoBiotechnology and Life Sciences Research, Alabama State University, Montgomery, AL, USA; 2Department of Microbiology, Osmania University, Hyderabad, IndiaAbstract: Carbon nanotubes (CNTs are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity.Keywords: carbon nanotubes, cytotoxicity, functionalization, biomedical applications

  14. Selective intercalation of polymers in carbon nanotubes.

    Science.gov (United States)

    Bazilevsky, Alexander V; Sun, Kexia; Yarin, Alexander L; Megaridis, Constantine M

    2007-07-03

    A room-temperature, open-air method is devised to selectively intercalate relatively low-molecular-weight polymers (approximately 10-100 kDa) from dilute, volatile solutions into open-end, as-grown, wettable carbon nanotubes with 50-100 nm diameters. The method relies on a novel self-sustained diffusion mechanism driving polymers from dilute volatile solutions into carbon nanotubes and concentrating them there. Relatively low-molecular-weight polymers, such as poly(ethylene oxide) (PEO, 600 kDa) and poly(caprolactone) (PCL, 80 kDa), were encapsulated in graphitic nanotubes as confirmed by transmission electron microscopy, which revealed morphologies characteristic of mixtures in nanoconfinements affected by intermolecular forces. Whereas relatively small, flexible polymer molecules can conform to enter these nanotubes, larger macromolecules (approximately 1000 kDa) remain outside. The selective nature of this process is useful for filling nanotubes with polymers and could also be valuable in capping nanotubes.

  15. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  16. Investigation of the formation of Fe-filled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Reuther, H [Forschungszentrum Dresden-Rossendorf, PO Box 510119, D-01314 Dresden (Germany); Mueller, C; Leonhardt, A; Kutz, M C, E-mail: reuther@fzd.d [Leibniz-Institute of Solid State and Materials Research Dresden, PO Box 270116, D-01171 Dresden (Germany)

    2010-03-01

    The formation of Fe-filled carbon nanotubes by thermal decomposition of ferrocene combined with a Fe-catalyst-nanostructuring on an oxidized Si substrate is investigated in the temperature range of 1015 - 1200 K. The optimal growth conditions for aligned and homogeneous carbon nanotubes are found at 1103 K. Moessbauer spectroscopy (both in transmission geometry and CEMS) was used to analyze and quantify the different formed Fe-phases. In general, {alpha}-Fe, {gamma}-Fe and Fe{sub 3}C are found to form within the carbon nanotubes. Depending on the growth conditions their fractions vary strongly. Moreover, an alignment of the {alpha}-Fe in the tubes could be detected.

  17. SYNTHESIS OF CARBON NANOTUBES FOR ACETYLENE DETECTION

    Directory of Open Access Journals (Sweden)

    M.Y. FAIZAH

    2008-04-01

    Full Text Available A gas sensor, utilizing carbon nanotubes (CNTs in a pellet form for acetylene detection has been developed. This research was carried out to investigate the absorption effect of acetylene (C2H2 towards the change of resistance of carbon nanotubes pellet as sensor signal. Source Measurement Unit (SMU was used to study the gas sensing behaviour of resistance based sensors employing carbon nanotubes pellet as the active sensing element. Studies revealed that the absorption of acetylene into the carbon nanotubes pellet resulting in increase in pellet resistance. The changes are attributed to p-type conductivity in semiconducting carbon nanotubes. Carbon nanotubes used in this research was synthesized by means of Floating Catalyst Chemical Vapor Deposition (FC-CVD method. Benzene was used as a hydrocarbon source while ferrocene as a source of catalyst with Hydrogen and Argon as carrier and purge gas respectively. From the research, it was shown that carbon nanotubes show high sensitivity towards acetylene. The highest sensitivity recorded was 1.21, 1.16 and 17.86 for S1, S2 and S3 respectively. It is expected that many applications of CNT-based sensors will be explored in future as the interest of the nanotechnology research in this field increases.

  18. A Tester for Carbon Nanotube Mode Lockers

    Science.gov (United States)

    Song, Yong-Won; Yamashita, Shinji

    2007-05-01

    We propose and demonstrate a tester for laser pulsating operation of carbon nanotubes employing a circulator with the extra degree of freedom of the second port to access diversified nanotube samples. The nanotubes are deposited onto the end facet of a dummy optical fiber by spray method that guarantees simple sample loading along with the minimized perturbation of optimized laser cavity condition. Resultant optical spectra, autocorrelation traces and pulse train of the laser outputs with qualified samples are presented.

  19. Enzymatic degradation of multiwalled carbon nanotubes.

    Science.gov (United States)

    Zhao, Yong; Allen, Brett L; Star, Alexander

    2011-09-01

    Because of their unique properties, carbon nanotubes and, in particular, multiwalled carbon nanotubes (MWNTs) have been used for the development of advanced composite and catalyst materials. Despite their growing commercial applications and increased production, the potential environmental and toxicological impacts of MWNTs are not fully understood; however, many reports suggest that they may be toxic. Therefore, a need exists to develop protocols for effective and safe degradation of MWNTs. In this article, we investigated the effect of chemical functionalization of MWNTs on their enzymatic degradation with horseradish peroxidase (HRP) and hydrogen peroxide (H(2)O(2)). We investigated HRP/H(2)O(2) degradation of purified, oxidized, and nitrogen-doped MWNTs and proposed a layer-by-layer degradation mechanism of nanotubes facilitated by side wall defects. These results provide a better understanding of the interaction between HRP and carbon nanotubes and suggest an eco-friendly way of mitigating the environmental impact of nanotubes.

  20. Carbon nanotube fiber spun from wetted ribbon

    Science.gov (United States)

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  1. Methods for producing reinforced carbon nanotubes

    Science.gov (United States)

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2008-10-28

    Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  2. Ordered phases of cesium in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jeong Won; Hwang, Ho Jung; Song, Ki Oh; Choi, Won Young; Byun, Ki Ryang [Chung-Ang University, Seoul (Korea, Republic of); Kwon, Oh Keun [Semyung University, Jecheon (Korea, Republic of); Lee, Jun Ha [Sangmyung University, Chonan (Korea, Republic of); Kim, Won Woo [Juseong College, Cheongwon (Korea, Republic of)

    2003-10-15

    We investigate the structural phases of Cs in carbon nanotubes by using a structural optimization process applied to an atomistic simulation method. As the radius of the carbon nanotubes is increased, the structures are found in various phases from an atomic strand to multishell packs composed of coaxial cylindrical shells. Both helical structures and layered structures are found. The numbers of helical atom rows composed of coaxial tubes and the orthogonal vectors of the circular rolling of a triangular network can explain the structural phases of Cs in carbon nanotubes.

  3. Microcapsule carbon nanotube devices for therapeutic applications

    Science.gov (United States)

    Kulamarva, Arun; Raja, Pavan M. V.; Bhathena, Jasmine; Chen, Hongmei; Talapatra, Saikat; Ajayan, Pulickel M.; Nalamasu, Omkaram; Prakash, Satya

    2009-01-01

    Carbon nanotubes are a new class of nanomaterials that have immense potential in the field of biomedicine. Their ability to carry large quantities of therapeutic molecules makes them prime candidates for providing targeted delivery of therapeutics for use in various diseases. However, their utility is limited due to the problems faced during their delivery to target sites. This article for the first time describes the design of a novel microcapsule carbon nanotube targeted delivery device. This device has potential in the targeted delivery of carbon nanotubes in suitable membranes along with their cargo, safely and effectively to the target loci.

  4. Highly oriented carbon nanotube papers made of aligned carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ding; Song Pengcheng; Liu Changhong; Wu Wei; Fan Shoushan [Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics, Tsinghua University, Beijing 100084 (China)], E-mail: chliu@tsinghua.edu.cn

    2008-02-20

    Paper-like carbon nanotube (CNT) materials have many important applications such as in catalysts, in filtration, actuators, capacitor or battery electrodes, and so on. Up to now, the most popular way of preparing buckypapers has involved the procedures of dispersion and filtration of a suspension of CNTs. In this work, we present a simple and effective macroscopic manipulation of aligned CNT arrays called 'domino pushing' in the preparation of the aligned thick buckypapers with large areas. This simple method can efficiently ensure that most of the CNTs are well aligned tightly in the buckypaper. The initial measurements indicate that these buckypapers have better performance on thermal and electrical conductance. These buckypapers with controllable structure also have many potential applications, including supercapacitor electrodes.

  5. Controlled Growth of Well-Defined Conjugated Polymers from the Surfaces of Multiwalled Carbon Nanotubes: Photoresponse Enhancement via Charge Separation.

    Science.gov (United States)

    Hou, Wenpeng; Zhao, Ning-Jiu; Meng, Dongli; Tang, Jing; Zeng, Yi; Wu, Yu; Weng, Yangziwan; Cheng, Chungui; Xu, Xiulai; Li, Yi; Zhang, Jian-Ping; Huang, Yong; Bielawski, Christopher W; Geng, Jianxin

    2016-05-24

    The installation of heterojunctions on the surfaces of carbon nanotubes (CNTs) is an effective method for promoting the charge separation processes needed for CNT-based electronics and optoelectronics applications. Conjugated polymers are proven state-of-the-art candidates for modifying the surfaces of CNTs. However, all previous attempts to incorporate conjugated polymers to CNTs resulted in unordered interfaces. Herein we show that well-defined chains of regioregular poly(3-hexylthiophene) (P3HT) were successfully grown from the surfaces of multiwalled CNTs (MWNTs) using surface-initiated Kumada catalyst-transfer polycondensation. The polymerization was found to proceed in a controlled manner as chains of tunable lengths were prepared through variation of the initial monomer-to-initiator ratio. Moreover, it was determined that large-diameter MWNTs afforded highly ordered P3HT aggregates, which exhibited a markedly bathochromically shifted optical absorption due to a high grafting density induced planarization of the polymer chains. Using ultrafast spectroscopy, the heterojunctions formed between the MWNTs and P3HT were shown to effectively overcome the binding energy of excitons, leading to photoinduced electron transfer from P3HT to MWNTs. Finally, when used as prototype devices, the individual MWNT-g-P3HT core-shell structures exhibited excellent photoresponses under a low illumination density.

  6. The electrical conduction variation in stained carbon nanotubes

    Science.gov (United States)

    Sun, Shih-Jye; Wei Fan, Jun; Lin, Chung-Yi

    2012-01-01

    Carbon nanotubes become stained from coupling with foreign molecules, especially from adsorbing gas molecules. The charge exchange, which is due to the orbital hybridization, occurred in the stained carbon nanotube induces electrical dipoles that consequently vary the electrical conduction of the nanotube. We propose a microscopic model to evaluate the electrical current variation produced by the induced electrical dipoles in a stained zigzag carbon nanotube. It is found that stronger orbital hybridization strengths and larger orbital energy differences between the carbon nanotube and the gas molecules help increasing the induced electrical dipole moment. Compared with the stain-free carbon nanotube, the induced electrical dipoles suppress the current in the nanotube. In the carbon nanotubes with induced dipoles the current increases as a result of increasing orbital energy dispersion via stronger hybridization couplings. In particular, at a fixed hybridization coupling, the current increases with the bond length for the donor-carbon nanotube but reversely for the acceptor-carbon nanotube.

  7. Methods for preparation of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Rakov, Eduard G [D.I. Mendeleev Russian University of Chemical Technology, Moscow (Russian Federation)

    2000-01-31

    The most important methods of synthesis and purification of carbon nanotubes, a new form of material, are described. The prospects for increasing the scale of preparation processes and for more extensive application of nanotubes are evaluated. The bibliography includes 282 references.

  8. Carbon nanotubes for RF and microwaves

    OpenAIRE

    Burke, P. J.; Yu, Z; Rutherglen, C.

    2005-01-01

    In this invited overview paper we provide a brief up-to-date summary of the potential applications of carbon nanotubes for RF and microwave devices and systems. We focus in particular on the use of nanotubes as ultra-high speed interconnects in integrated circuits.

  9. Carbon nanotubes as heat dissipaters in microelectronics

    DEFF Research Database (Denmark)

    Pérez Paz, Alejandro; García-Lastra, Juan María; Markussen, Troels

    2013-01-01

    We review our recent modelling work of carbon nanotubes as potential candidates for heat dissipation in microelectronics cooling. In the first part, we analyze the impact of nanotube defects on their thermal transport properties. In the second part, we investigate the loss of thermal properties...

  10. Carbon Nanotubes for Human Space Flight

    Science.gov (United States)

    Scott, Carl D.; Files, Brad; Yowell, Leonard

    2003-01-01

    Single-wall carbon nanotubes offer the promise of a new class of revolutionary materials for space applications. The Carbon Nanotube Project at NASA Johnson Space Center has been actively researching this new technology by investigating nanotube production methods (arc, laser, and HiPCO) and gaining a comprehensive understanding of raw and purified material using a wide range of characterization techniques. After production and purification, single wall carbon nanotubes are processed into composites for the enhancement of mechanical, electrical, and thermal properties. This "cradle-to-grave" approach to nanotube composites has given our team unique insights into the impact of post-production processing and dispersion on the resulting material properties. We are applying our experience and lessons-learned to developing new approaches toward nanotube material characterization, structural composite fabrication, and are also making advances in developing thermal management materials and electrically conductive materials in various polymer-nanotube systems. Some initial work has also been conducted with the goal of using carbon nanotubes in the creation of new ceramic materials for high temperature applications in thermal protection systems. Human space flight applications such as advanced life support and fuel cell technologies are also being investigated. This discussion will focus on the variety of applications under investigation.

  11. Synthesis and Characterization of Carbon Nanotubes for Reinforced and Functional Applications

    Science.gov (United States)

    Zhu, Shen; Su, C.-H.; Lehoczky, S.; Watson, M.

    2003-01-01

    Many efforts have been engaged recently in synthesizing single-walled and multi-walled carbon nanotubes due to their superior mechanical, electrical and thermal properties, which could be used for numerous applications to enhance the performance of electronics, sensors and composites. This presentation will demonstrate the synthesizing process of carbon nanotube by thermal chemical vapor deposition and the characterization results by using electron microscopy and optical spectroscopy. Carbon nanotubes could be synthesized on various substances. The conditions of fabricating single-walled or multi-walled carbon nanotubes depend strongly on temperature and hydrocarbon concentration but weakly on pressure. The sizes, orientations, and growth modes of carbon nanotubes will be illustrated. The advantages and limitations of several potential aerospace applications such as reinforced and functional composites, temperature sensing, and thermal control by using carbon nanotubes will be discussed.

  12. Coulomb drag in multiwall armchair carbon nanotubes

    DEFF Research Database (Denmark)

    Lunde, A.M.; Jauho, Antti-Pekka

    2004-01-01

    We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...

  13. Microfabricated electroactive carbon nanotube actuators

    Science.gov (United States)

    Ahluwalia, Arti; Baughman, Ray H.; De Rossi, Danilo; Mazzoldi, Alberto; Tesconi, Mario; Tognetti, Alessandro; Vozzi, Giovanni

    2001-07-01

    A variety of microfabrication techniques have been developed at the University of Pisa. They are based either on pressure or piston actuated microsyringes or modified ink-jet printers. This work present the results of a study aimed at fabricating carbon nanotube (NT) actuators using micro-syringes. In order to prevent the nanotubes from aggregating into clumps, they were enclosed in a partially cross-linked polyvinylalcohol - polyallylamine matrix. After sonication the solution remained homogenously dispersed for about 40 minutes, which was sufficient time for deposition. Small strips of NT, about 5 mm across and 15 mm long were deposited. Following deposition, the films were baked at 80 degree(s)C and their thickness, impedance and mechanical resistance measured. The results indicate that 50 minutes of baking time is sufficient to give a constant resistivity of 1.12 x 10-2 (Omega) m per layer similar to a typical semiconductor, and each layer has a thickness of about 6 micrometers .

  14. Flightweight Carbon Nanotube Magnet Technology

    Science.gov (United States)

    Chapman, J. N.; Schmidt, H. J.; Ruoff, R. S.; Chandrasekhar, V.; Dikin, D. A.; Litchford, R. J.

    2003-01-01

    Virtually all plasma-based systems for advanced airborne/spaceborne propulsion and power depend upon the future availability of flightweight magnet technology. Unfortunately, current technology for resistive and superconducting magnets yields system weights that tend to counteract the performance advantages normally associated with advanced plasma-based concepts. The ongoing nanotechnology revolution and the continuing development of carbon nanotubes (CNT), however, may ultimately relieve this limitation in the near future. Projections based on recent research indicate that CNTs may achieve current densities at least three orders of magnitude larger than known superconductors and mechanical strength two orders of magnitude larger than steel. In fact, some published work suggests that CNTs are superconductors. Such attributes imply a dramatic increase in magnet performance-to-weight ratio and offer real hope for the construction of true flightweight magnets. This Technical Publication reviews the technology status of CNTs with respect to potential magnet applications and discusses potential techniques for using CNT wires and ropes as a winding material and as an integral component of the containment structure. The technology shortfalls are identified and a research and technology strategy is described that addresses the following major issues: (1) Investigation and verification of mechanical and electrical properties, (2) development of tools for manipulation and fabrication on the nanoscale, (3) continuum/molecular dynamics analysis of nanotube behavior when exposed to practical bending and twisting loads, and (4) exploration of innovative magnet fabrication techniques that exploit the natural attributes of CNTs.

  15. Single-wall and multi-wall carbon nanotubes promote rice root growth by eliciting the similar molecular pathways and epigenetic regulation.

    Science.gov (United States)

    Yan, Shihan; Zhang, Hao; Huang, Yan; Tan, Junjun; Wang, Pu; Wang, Yapei; Hou, Haoli; Huang, Jin; Li, Lijia

    2016-08-01

    Organisms are constantly exposed to environmental stimuli and have evolved mechanisms of protection and adaptation. Various effects of nanoparticles (NPs) on crops have been described and some results confirm that NPs could enhance plant growth at the physiological and genetic levels. This study comparatively analysed the effect of carbon nanotubes (CNTs) on rice growth. The results showed that single-wall CNTs were located in the intercellular space while multi-wall CNTs penetrated cell walls in roots. CNTs could promote rice root growth through the regulation of expression of the root growth related genes and elevated global histone acetylation in rice root meristem zones. These responses were returned to normal levels after CNTs were removed from medium. CNTs caused the similar histone acetylation and methylation statuses across the local promoter region of the Cullin-RING ligases 1 (CRL1) gene and increased micrococcal nuclease accessibility of this region, which enhanced this gene expression. The authors results suggested that CNTs could cause plant responses at the cellular, genetic, and epigenetic levels and these responses were independent on interaction modes between root cells and CNTs.

  16. Effects of charge distribution on water filling process in carbon nanotube

    Institute of Scientific and Technical Information of China (English)

    MENG LingYi; LI QiKai; SHUAI ZhiGang

    2009-01-01

    Using umbrella sampling technique with molecular dynamics simulation, we investigated the nanoflu-idic transport of water in carbon nanotube (CNT). The simulations showed that a positive charge modi-fication to the carbon nanotube can slow down the water column growth process, while the negative charge modification to the carbon nanotube will, on the other hand, quicken the water column growth process. The free energy curves were obtained through the statistical process of water column growth under different charge distributions, and the results indicated that these free energy curves can be employed to explain the dynamical process of water column growth in the nanosized channels.

  17. Effects of charge distribution on water filling process in carbon nanotube

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Using umbrella sampling technique with molecular dynamics simulation,we investigated the nanoflu-idic transport of water in carbon nanotube(CNT).The simulations showed that a positive charge modi-fication to the carbon nanotube can slow down the water column growth process,while the negative charge modification to the carbon nanotube will,on the other hand,quicken the water column growth process.The free energy curves were obtained through the statistical process of water column growth under different charge distributions,and the results indicated that these free energy curves can be employed to explain the dynamical process of water column growth in the nanosized channels.

  18. Modification of carbon nanotubes and synthesis of polymeric composites involving the nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Badamshina, E R; Gafurova, M P; Estrin, Yakov I [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2010-12-29

    The results of studies, mainly published in recent years, on modification of carbon nanotubes and design of composites with these nanotubes for the manufacture of new-generation materials are generalized and analyzed. The methods of modification of the nanotubes by low- and high-molecular compounds and methods of polymer modification by carbon nanotubes are considered. Data on the properties of modified nanotubes are presented. The current and potential applications of materials based on the nanotubes are indicated.

  19. Film fabrication of Fe or Fe3O4 nanoparticles mixed with palmitic acid for vertically aligned carbon nanotube growth using Langmuir-Blodgett technique

    Science.gov (United States)

    Nakamura, Kentaro; Kuriyama, Naoki; Takagiwa, Shota; Sato, Taiga; Kushida, Masahito

    2016-03-01

    Vertically aligned carbon nanotubes (VA-CNTs) were studied as a new catalyst support for polymer electrolyte fuel cells (PEFCs). Controlling the number density and the diameter of VA-CNTs may be necessary to optimize PEFC performance. As the catalyst for CNT growth, we fabricated Fe or Fe3O4 nanoparticle (NP) films by the Langmuir-Blodgett (LB) technique. The catalyst Fe or Fe3O4 NPs were widely separated by mixing with filler molecules [palmitic acid (C16)]. The number density of VA-CNTs was controlled by varying the ratio of catalyst NPs to C16 filler molecules. The VA-CNTs were synthesized from the catalyst NP-C16 LB films by thermal chemical vapor deposition (CVD) using acetylene gas as the carbon source. The developing solvents used in the LB technique and the hydrogen reduction conditions of CVD were optimized to improve the VA-CNT growth rate. We demonstrate that the proposed method can independently control both the density and the diameter of VA-CNTs.

  20. Purification of Carbon Nanotubes: Alternative Methods

    Science.gov (United States)

    Files, Bradley; Scott, Carl; Gorelik, Olga; Nikolaev, Pasha; Hulse, Lou; Arepalli, Sivaram

    2000-01-01

    Traditional carbon nanotube purification process involves nitric acid refluxing and cross flow filtration using surfactant TritonX. This is believed to result in damage to nanotubes and surfactant residue on nanotube surface. Alternative purification procedures involving solvent extraction, thermal zone refining and nitric acid refiuxing are used in the current study. The effect of duration and type of solvent to dissolve impurities including fullerenes and P ACs (polyaromatic compounds) are monitored by nuclear magnetic reasonance, high performance liquid chromatography, and thermogravimetric analysis. Thermal zone refining yielded sample areas rich in nanotubes as seen by scanning electric microscopy. Refluxing in boiling nitric acid seem to improve the nanotube content. Different procedural steps are needed to purify samples produced by laser process compared to arc process. These alternative methods of nanotube purification will be presented along with results from supporting analytical techniques.

  1. Deconvoluting hepatic processing of carbon nanotubes

    Science.gov (United States)

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-07-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans.

  2. Carbon Nanotube Composites: Strongest Engineering Material Ever?

    Science.gov (United States)

    Mayeaux, Brian; Nikolaev, Pavel; Proft, William; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    The primary goal of the carbon nanotube project at Johnson Space Center (JSC) is to fabricate structural materials with a much higher strength-to-weight ratio than any engineered material today, Single-wall nanotubes present extraordinary mechanical properties along with new challenges for materials processing. Our project includes nanotube production, characterization, purification, and incorporation into applications studies. Now is the time to move from studying individual nanotubes to applications work. Current research at JSC focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. These nanoscale fibers present unique new challenges to composites engineers. Preliminary studies show good nanotube dispersion and wetting by the epoxy materials. Results of tensile strength tests will also be reported. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical uses.

  3. Functionalized carbon nanotubes: biomedical applications.

    Science.gov (United States)

    Vardharajula, Sandhya; Ali, Sk Z; Tiwari, Pooja M; Eroğlu, Erdal; Vig, Komal; Dennis, Vida A; Singh, Shree R

    2012-01-01

    Carbon nanotubes (CNTs) are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity.

  4. Carbon Nanotube Tape Vibrating Gyroscope

    Science.gov (United States)

    Tucker, Dennis Stephen (Inventor)

    2016-01-01

    A vibrating gyroscope includes a piezoelectric strip having length and width dimensions. The piezoelectric strip includes a piezoelectric material and carbon nanotubes (CNTs) substantially aligned and polled along the strip's length dimension. A spindle having an axis of rotation is coupled to the piezoelectric strip. The axis of rotation is parallel to the strip's width dimension. A first capacitance sensor is mechanically coupled to the spindle for rotation therewith. The first capacitance sensor is positioned at one of the strip's opposing ends and is spaced apart from one of the strip's opposing faces. A second capacitance sensor is mechanically coupled to the spindle for rotation therewith. The second capacitance sensor is positioned at another of the strip's opposing ends and is spaced apart from another of the strip's opposing faces. A voltage source applies an AC voltage to the piezoelectric strip.

  5. Carbon nanotubes – becoming clean

    Directory of Open Access Journals (Sweden)

    Nicole Grobert

    2007-01-01

    Full Text Available Carbon nanotubes (CNTs are now well into their teenage years. Early on, theoretical predictions and experimental data showed that CNTs possess chemical and mechanical properties that exceed those of many other materials. This has triggered intense research into CNTs. A variety of production methods for CNTs have been developed; chemical modification, functionalization, filling, and doping have been achieved; and manipulation, separation, and characterization of individual CNTs is now possible. Today, products containing CNTs range from tennis rackets and golf clubs to vehicle fenders, X-ray tubes, and Li ion batteries. Breakthroughs for CNT-based technologies are anticipated in the areas of nanoelectronics, biotechnology, and materials science. In this article, I review the current situation in CNT production and highlight the importance of clean CNT material for the success of future applications.

  6. Carbon nanotube polymer composition and devices

    Science.gov (United States)

    Liu, Gao; Johnson, Stephen; Kerr, John B.; Minor, Andrew M.; Mao, Samuel S.

    2011-06-14

    A thin film device and compound having an anode, a cathode, and at least one light emitting layer between the anode and cathode, the at least one light emitting layer having at least one carbon nanotube and a conductive polymer.

  7. Carbon nanotube heat-exchange systems

    Science.gov (United States)

    Hendricks, Terry Joseph; Heben, Michael J.

    2008-11-11

    A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

  8. A Thermal Model for Carbon Nanotube Interconnects

    Directory of Open Access Journals (Sweden)

    Clay Mayberry

    2013-04-01

    Full Text Available In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.

  9. Fabrication of porous carbon nanotube network.

    Science.gov (United States)

    Su, Jun-Wei; Fu, Shu-Juan; Gwo, Shangjr; Lin, Kuan-Jiuh; Lin, Kuna-Jiuh

    2008-11-21

    We used the spin-coating method combined with ultrasonic atomization as a continuous, one-step process to generate a two-dimensional honeycomb network that was constructed from pure multi-walled carbon nanotubes.

  10. Self Assembled Carbon Nanotube Enhanced Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA STTR program is to develop single wall carbon nanotube (SWCNT) based ultracapacitors for energy storage devices (ESD) application, using...

  11. Piezoresistive Sensors Based on Carbon Nanotube Films

    Institute of Scientific and Technical Information of China (English)

    L(U) Jian-wei; WANG Wan-lu; LIAO Ke-jun; WANG Yong-tian; LIU CHang-lin; Zeng Qing-gao

    2005-01-01

    Piezoresistive effect of carbon nanotube films was investigated by a three-point bending test.Carbon nanotubes were synthesized by hot filament chemical vapor deposition.The experimental results showed that the carbon nanotubes have a striking piezoresistive effect.The relative resistance was changed from 0 to 10.5×10-2 and 3.25×10-2 for doped and undoped films respectively at room temperature when the microstrain under stress from 0 to 500. The gauge factors for doped and undoped carbon nanotube films under 500 microstrain were about 220 and 67 at room temperature, respectively, exceeding that of polycrystalline silicon (30) at 35℃.The origin of the resistance changes in the films may be attributed to a strain-induced change in the band gap for the doped tubes and the defects for the undoped tubes.

  12. Fermentation based carbon nanotube multifunctional bionic composites

    Science.gov (United States)

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-06-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal.

  13. Catalyst deposition for the preparation of carbon nanotubes

    DEFF Research Database (Denmark)

    2013-01-01

    Disclosed is a method of depositing islands of catalyst with a predetermined density, wherein in said method comprises the steps of: obtaining a diffusion barrier covered nano patterned surface comprising a plurality of plateaus, having a density of plateaus dependent on the predetermined density...... patterned surface is configured to ensure that no more than a single island of catalyst is formed on each plateau, so that a sub sequent growth of carbon nanotubes from the deposited islands result in that no more than a single carbon nanotube is grown from each plateau....

  14. Controlled Deposition and Alignment of Carbon Nanotubes

    Science.gov (United States)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2012-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  15. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.

    2016-12-13

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  16. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.

    2016-11-15

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  17. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.

    2016-10-25

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  18. [Hygienic evaluation of multilayer carbon nanotubes].

    Science.gov (United States)

    Haliullin, T O; Zalyalov, R R; Shvedova, A A; Tkachov, A G

    2015-01-01

    The authors demonstrate that traditional methods evaluating work conditions on contemporary innovative enterprises producing nanomaterials assess these conditions as harmless and safe. At the same time, special investigation methods enable to reveal new hazards for workers' health: the study results prove that workers engaged into multilayer carbon nanotubes production are exposed to multilayer carbon nanotubes aerosols in concentrations exceeding internationally acceptable levels of 1 μg/ml (NIOSH)--that can harm the workers' health.

  19. Carbon nanotube temperature and pressure sensors

    Science.gov (United States)

    Ivanov, Ilia N; Geohegan, David Bruce

    2013-10-29

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  20. Carbon nanotubes field effect transistors biosensors

    OpenAIRE

    Martínez, M.T.; Tseng, Y. C.; Ormategui, N.; Loinaz, I.; Eritja Casadellà, Ramón; Salvador, Juan Pablo; Marco, María Pilar; Bokor, J.

    2012-01-01

    [EN] Carbon nanotube transistor arrays (CNTFETs) were used as biosensors to detect NA hybridization and to recognize two anabolic steroids, stanozolol (Stz) and methylboldenone (MB). Single strand DNA and antibodies specific for STz and MB were immobilized on the carbon nanotubes (CNTs) in situ in the device using two different approaches: direct noncovalent bonding of antibodies to the devices and covalently trough a polymer previously attached to the CNTFETs. A new approach to ensure specif...

  1. Integrating Carbon Nanotubes For Atomic Force Microscopy Imaging Applications

    Science.gov (United States)

    Ye, Qi; Cassell, Alan M.; Liu, Hongbing; Han, Jie; Meyyappan, Meyya

    2004-01-01

    Carbon nanotube (CNT) related nanostructures possess remarkable electrical, mechanical, and thermal properties. To produce these nanostructures for real world applications, a large-scale controlled growth of carbon nanotubes is crucial for the integration and fabrication of nanodevices and nanosensors. We have taken the approach of integrating nanopatterning and nanomaterials synthesis with traditional silicon micro fabrication techniques. This integration requires a catalyst or nanomaterial protection scheme. In this paper, we report our recent work on fabricating wafer-scale carbon nanotube AFM cantilever probe tips. We will address the design and fabrication considerations in detail, and present the preliminary scanning probe test results. This work may serve as an example of rational design, fabrication, and integration of nanomaterials for advanced nanodevice and nanosensor applications.

  2. Carbon Nanotubes for Thin Film Transistor: Fabrication, Properties, and Applications

    Directory of Open Access Journals (Sweden)

    Yucui Wu

    2013-01-01

    Full Text Available We review the present status of single-walled carbon nanotubes (SWCNTs for their production and purification technologies, as well as the fabrication and properties of single-walled carbon nanotube thin film transistors (SWCNT-TFTs. The most popular SWCNT growth method is chemical vapor deposition (CVD, including plasma-enhanced chemical vapor deposition (PECVD, floating catalyst chemical vapor deposition (FCCVD, and thermal CVD. Carbon nanotubes (CNTs used to fabricate thin film transistors are sorted by electrical breakdown, density gradient ultracentrifugation, or gel-based separation. The technologies of applying CNT random networks to work as the channels of SWCNT-TFTs are also reviewed. Excellent work from global researchers has been benchmarked and analyzed. The unique properties of SWCNT-TFTs have been reviewed. Besides, the promising applications of SWCNT-TFTs have been explored. Finally, the key issues to be solved in future have been summarized.

  3. High-throughput optical imaging and spectroscopy of individual carbon nanotubes in devices.

    Science.gov (United States)

    Liu, Kaihui; Hong, Xiaoping; Zhou, Qin; Jin, Chenhao; Li, Jinghua; Zhou, Weiwei; Liu, Jie; Wang, Enge; Zettl, Alex; Wang, Feng

    2013-12-01

    Single-walled carbon nanotubes are uniquely identified by a pair of chirality indices (n,m), which dictate the physical structures and electronic properties of each species. Carbon nanotube research is currently facing two outstanding challenges: achieving chirality-controlled growth and understanding chirality-dependent device physics. Addressing these challenges requires, respectively, high-throughput determination of the nanotube chirality distribution on growth substrates and in situ characterization of the nanotube electronic structure in operating devices. Direct optical imaging and spectroscopy techniques are well suited for both goals, but their implementation at the single nanotube level has remained a challenge due to the small nanotube signal and unavoidable environment background. Here, we report high-throughput real-time optical imaging and broadband in situ spectroscopy of individual carbon nanotubes on various substrates and in field-effect transistor devices using polarization-based microscopy combined with supercontinuum laser illumination. Our technique enables the complete chirality profiling of hundreds of individual carbon nanotubes, both semiconducting and metallic, on a growth substrate. In devices, we observe that high-order nanotube optical resonances are dramatically broadened by electrostatic doping, an unexpected behaviour that points to strong interband electron-electron scattering processes that could dominate ultrafast dynamics of excited states in carbon nanotubes.

  4. Growth and physico-chemical properties of interconnected carbon nanotubes in FeSBA-15 mesoporous molecular sieves

    Directory of Open Access Journals (Sweden)

    Ulka Suryavanshi

    2016-03-01

    Full Text Available Carbon nanotubes (CNTs with well-defined hollow interiors, and different morphologies have been grown inside the nanochannels of iron substituted SBA-15 (Santa Barbara Amorphous with different iron contents and well-ordered large mesopores by chemical vapour deposition method. This novel method requires only 3 min for the formation of high quality multiwalled CNTs inside the SBA-15. The physico-chemical characteristics of the prepared CNT/Fe-SBA-15 nanocomposite have been analysed with powder X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy and thermogravimetric analysis (TGA. XRD, Raman spectroscopy and TGA results confirm that the formed CNTs in SBA-15 nanochannels are highly pure and graphitic in nature, which can be altered by tuning the Fe content in the support matrix. SEM images show the interconnected network of SBA-15/CNT where CNT bridges the neighbouring SBA-15 nanoparticles. Interestingly, spring like CNTs and multi-terminal junctions such as Y and H junctions were also observed. The morphology of the CNTs inside the nanochannels of the SBA-15 support can also be controlled by the simple adjustment of the iron content in the SBA-15 framework. It has also been found that the content of Fe in the silica framework of SBA-15 plays a significant role in the formation of the CNTs and the amount of deposited CNTs in the nanochannels of SBA-15 increased with increasing the concentration of iron in framework. Among the materials studied, the FeSBA-15 with the nSi/nFe ratio of 2 showed the highest catalytic activity towards the formation of high quality CNTs.

  5. Filling of carbon nanotubes and nanofibres

    Directory of Open Access Journals (Sweden)

    Reece D. Gately

    2015-02-01

    Full Text Available The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications.

  6. ON THE CONTINUUM MODELING OF CARBON NANOTUBES

    Institute of Scientific and Technical Information of China (English)

    张鹏; 黄永刚; Philippe H.Geubelle; 黄克智

    2002-01-01

    We have recently proposed a nanoscale continuum theory for carbonnanotubes. The theory links continuum analysis with atomistic modeling by incor-porating interatomic potentials and atomic structures of carbon nanotubes directlyinto the constitutive law. Here we address two main issues involved in setting upthe nanoscale continuum theory for carbon nanotubes, namely the multi-body in-teratomic potentials and the lack of centrosymmetry in the nanotube structure. Weexplain the key ideas behind these issues in establishing a nanoscale continuum theoryin terms of interatomic potentials and atomic structures.

  7. Bone Marrow Stem Cells Response to Collagen/Single-Wall Carbon Nanotubes-COOHs Nanocomposite Films with Transforming Growth Factor Beta 1.

    Science.gov (United States)

    Wang, Jianhua; He, Chaolong; Cheng, Niangmei; Yang, Qiu; Chen, Mingmao; You, Lijun; Zhang, Qiqing

    2015-07-01

    Single-wall carbon nanotubes (SWNTs) have attractive biochemical properties such as strong cell adhesion and protein absorption, which are very useful for a cell cultivation scaffold. In this study, collagen/SWNT-COOHs nanocomposite films composed of regenerated fish collagen and SWNT-COOHs (0, 0.5, 1.0 and 2.0 weight percent) were prepared by mixing solubilized pepsin-soluble collagen with solutions of SWNT-COOHs. Morphological observation by SEM indicated the homogenous dispersion of SWNT-COOHs in the collagen matrix. The application of FTIR confirmed that the process we applied to prepare the composites did not destroy the native structures of collagen and composites were crosslinked by D-ribose. The biocompatibility was evaluated in vitro using SD rat bone marrow stem cells (BMSCs). Compared with films without transforming growth factor beta 1 (TGF-β1), films with TGF-β1 had superior performance on promotion of cell growth. Compared with pure collagen film with TGF-β1, SWNT-containing films might promote cellular functions by adsorbing more growth factors. In conclusion, the study suggested that the collagen/SWNT-COOHs nanocomposite films with TGF-β1 were expected to be useful scaffolds in cartilage tissue engineering.

  8. Method for nano-pumping using carbon nanotubes

    Science.gov (United States)

    Insepov, Zeke; Hassanein, Ahmed

    2009-12-15

    The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

  9. Fast readout of carbon nanotube mechanical resonators

    Science.gov (United States)

    Meerwaldt, Harold; Singh, Vibhor; Schneider, Ben; Schouten, Raymond; van der Zant, Herre; Steele, Gary

    2013-03-01

    We perform fast readout measurements of carbon nanotube mechanical resonators. Using an electronic mixing scheme, we can detect the amplitude of the mechanical motion with an intermediate frequency (IF) of 46 MHz and a timeconstant of 1 us, up to 5 orders of magnitude faster than before. Previous measurements suffered from a low bandwidth due to the combination of the high resistance of the carbon nanotube and a large stray capacitance. We have increased the bandwidth significantly by using a high-impedance, close-proximity HEMT amplifier. The increased bandwidth should allow us to observe the nanotube's thermal motion and its transient response, approaching the regime of real-time detection of the carbon nanotube's mechanical motion.

  10. Manipulation and cutting of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Nanomanipulation plays an important role in nanofabrication, it is also a technology necessary in exploring the secrets of nanoworld, and it thus beco mesa start point to research future nanomachine. In this study, manipulation and cutting of carbon nanotubes have been conducted in order to examine whether we can move a nanocomponent from one site to another by using the tip of atomic fo rce microscope (AFM). The technique may also be valuable for providing the const ructive materials of nanofabrication. While exploring the method for manipulatin g and cutting of nanotubes, some new phenomena have been observed during the process. Results show that carbon nanotubes present a feature of deformation combin ing bending and distortion when subjected to large mechanical forces exerted by the tip of AFM. In special cases, long carbon nanotubes can be cut into two part s, by which we can remove the part where crystal lattice is flawed, and therefor e a perfect nanocomponent can be obtained.

  11. Synthesis of carbon nanotubes by plasma-enhanced CVD process: gas phase study of synthesis conditions

    OpenAIRE

    Guláš, Michal; Cojocaru, Costel Sorin; Fleaca, Claudiu; Farhat, Samir; Veis, Pavel; Le Normand, Francois

    2008-01-01

    International audience; To support experimental investigations, a model based on ChemkinTM software was used to simulate gas phase and surface chemistry during plasma-enhanced catalytic CVD of carbon nanotubes. According to these calculations, gas phase composition, etching process and growth rates are calculated. The role of several carbon species, hydrocarbon molecules and ions in the growth mechanism of carbon nanotubes is presented in this study. Study of different conditions of gas phase ...

  12. Static and dynamic wetting measurements of single carbon nanotubes.

    Science.gov (United States)

    Barber, Asa H; Cohen, Sidney R; Wagner, H Daniel

    2004-05-07

    Individual carbon nanotubes were immersed and removed from various organic liquids using atomic force microscopy. The carbon nanotube-liquid interactions could be monitored in situ, and accurate measurements of the contact angle between liquids and the nanotube surface were made. These wetting data were used to produce Owens and Wendt plots giving the dispersive and polar components of the nanotube surface.

  13. Center for Applications of Single-Walled Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Resasco, Daniel E

    2008-02-21

    This report describes the activities conducted under a Congressional Direction project whose goal was to develop applications for Single-walled carbon nanotubes, under the Carbon Nanotube Technology Center (CANTEC), a multi-investigator program that capitalizes on OU’s advantageous position of having available high quality carbon nanotubes. During the first phase of CANTEC, 11 faculty members and their students from the College of Engineering developed applications for carbon nanotubes by applying their expertise in a number of areas: Catalysis, Reaction Engineering, Nanotube synthesis, Surfactants, Colloid Chemistry, Polymer Chemistry, Spectroscopy, Tissue Engineering, Biosensors, Biochemical Engineering, Cell Biology, Thermal Transport, Composite Materials, Protein synthesis and purification, Molecular Modeling, Computational Simulations. In particular, during this phase, the different research groups involved in CANTEC made advances in the tailoring of Single-Walled Carbon Nanotubes (SWNT) of controlled diameter and chirality by Modifying Reaction Conditions and the Nature of the catalyst; developed kinetic models that quantitatively describe the SWNT growth, created vertically oriented forests of SWNT by varying the density of metal nanoparticles catalyst particles, and developed novel nanostructured SWNT towers that exhibit superhydrophobic behavior. They also developed molecular simulations of the growth of Metal Nanoparticles on the surface of SWNT, which may have applications in the field of fuell cells. In the area of biomedical applications, CANTEC researchers fabricated SWNT Biosensors by a novel electrostatic layer-by-layer (LBL) deposition method, which may have an impact in the control of diabetes. They also functionalized SWNT with proteins that retained the protein’s biological activity and also retained the near-infrared light absorbance, which finds applications in the treatment of cancer.

  14. Oscillatory characteristics of carbon nanotubes inside carbon nanotube bundles

    Science.gov (United States)

    Ansari, R.; Alipour, A.; Sadeghi, F.

    2012-12-01

    This article presents a comprehensive study on the mechanics of carbon nanotubes (CNTs) oscillating in CNT bundles. Using the continuum approximation along with Lennard-Jones (LJ) potential function, new semi-analytical expressions in terms of double integrals are presented to evaluate van der Waals (vdW) potential energy and interaction force upon which the equation of motion is directly solved. The obtained potential expression enables one to arrive at a new semi-analytical formula for the exact evaluation of oscillation frequency. Also, an algebraic frequency formula is extracted on the basis of the simplifying assumption of constant vdW force. Based on the present expressions, a thorough study on various aspects of operating frequencies under different system parameters is given, which permits fresh insight into the problem. The strong dependence of oscillation frequency on system parameters, such as the extrusion distance and initial velocity of the core as initial conditions for the motion is indicated. Interestingly, a specific initial velocity is found at which the oscillation frequency is independent of the core length. In addition, a relation between this specific initial velocity and the escape velocity is disclosed.

  15. Carbon nanotubes and graphene towards soft electronics

    Science.gov (United States)

    Chae, Sang Hoon; Lee, Young Hee

    2014-04-01

    Although silicon technology has been the main driving force for miniaturizing device dimensions to improve cost and performance, the current application of Si to soft electronics (flexible and stretchable electronics) is limited due to material rigidity. As a result, various prospective materials have been proposed to overcome the rigidity of conventional Si technology. In particular, nano-carbon materials such as carbon nanotubes (CNTs) and graphene are promising due to outstanding elastic properties as well as an excellent combination of electronic, optoelectronic, and thermal properties compared to conventional rigid silicon. The uniqueness of these nano-carbon materials has opened new possibilities for soft electronics, which is another technological trend in the market. This review covers the recent progress of soft electronics research based on CNTs and graphene. We discuss the strategies for soft electronics with nano-carbon materials and their preparation methods (growth and transfer techniques) to devices as well as the electrical characteristics of transparent conducting films (transparency and sheet resistance) and device performances in field effect transistor (FET) (structure, carrier type, on/off ratio, and mobility). In addition to discussing state of the art performance metrics, we also attempt to clarify trade-off issues and methods to control the trade-off on/off versus mobility). We further demonstrate accomplishments of the CNT network in flexible integrated circuits on plastic substrates that have attractive characteristics. A future research direction is also proposed to overcome current technological obstacles necessary to realize commercially feasible soft electronics.

  16. 75 FR 56880 - Multi-Walled Carbon Nanotubes and Single-Walled Carbon Nanotubes; Significant New Use Rules

    Science.gov (United States)

    2010-09-17

    ... structural characteristics entitled ``Material Characterization of Carbon Nanotubes for Molecular Identity... AGENCY 40 CFR Parts 9 and 721 RIN 2070-AB27 Multi-Walled Carbon Nanotubes and Single-Walled Carbon...). The two chemical substances are identified generically as multi-walled carbon nanotubes (MWCNT) (PMN...

  17. Effects of O 2 and N 2/H 2 plasma treatments on the neuronal cell growth on single-walled carbon nanotube paper scaffolds

    Science.gov (United States)

    Yoon, Ok Ja; Lee, Hyun Jung; Jang, Yeong Mi; Kim, Hyun Woo; Lee, Won Bok; Kim, Sung Su; Lee, Nae-Eung

    2011-08-01

    The O 2 and N 2/H 2 plasma treatments of single-walled carbon nanotube (SWCNT) papers as scaffolds for enhanced neuronal cell growth were conducted to functionalize their surfaces with different functional groups and to roughen their surfaces. To evaluate the effects of the surface roughness and functionalization modifications of the SWCNT papers, we investigated the neuronal morphology, mitochondrial membrane potential, and acetylcholine/acetylcholinesterase levels of human neuroblastoma during SH-SY5Y cell growth on the treated SWCNT papers. Our results demonstrated that the plasma-chemical functionalization caused changes in the surface charge states with functional groups with negative and positive charges and then the increased surface roughness enhanced neuronal cell adhesion, mitochondrial membrane potential, and the level of neurotransmitter in vitro. The cell adhesion and mitochondrial membrane potential on the negatively charged SWCNT papers were improved more than on the positively charged SWCNT papers. Also, measurements of the neurotransmitter level showed an enhanced acetylcholine level on the negatively charged SWCNT papers compared to the positively charged SWCNT papers.

  18. Carbon Nanotube-Based Synthetic Gecko Tapes

    Science.gov (United States)

    Dhinojwala, Ali

    2008-03-01

    Wall-climbing geckos have unique ability to attach to different surfaces without the use of any viscoelastic glues. On coming in contact with any surface, the micron-size gecko foot-hairs deform, enabling molecular contact over large areas, thus translating weak van der Waals (vdW) interactions into enormous shear forces. We will present our recent results on the development of synthetic gecko tape using aligned carbon nanotubes to mimic the keratin hairs found on gecko feet. The patterned carbon nanotube-based gecko tape can support a shear stress (36 N/cm^2) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micron-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak vdW interactions into high shear forces. The carbon nanotube based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics and space applications. The mechanism behind these large shear forces and self-cleaning properties of these carbon nanotube based synthetic gecko tapes will be discussed. This work was performed in collaboration with graduate students Liehui Ge, and Sunny Sethi, and collaborators from RPI; Lijie Ci and Professor Pulickel Ajayan.

  19. Carbon nanotube based NEMS actuators and sensors

    Science.gov (United States)

    Forney, Michael; Poler, Jordan

    2011-03-01

    Single-walled carbon nanotubes (SWNTs) have been widely studied due to superior mechanical and electrical properties. We have grown vertically aligned SWNTs (VA-SWNTs) onto microcantilever (MC) arrays, which provides an architecture for novel actuators and sensors. Raman spectroscopy confirms that the CVD-grown nanotubes are SWNTs and SEM confirms aligned growth. As an actuator, this hybrid MC/VA-SWNT system can be electrostatically modulated. SWNTs are excellent electron acceptors, so we can charge up the VA-SWNT array by applying a voltage. The electrostatic repulsion among the charged SWNTs provides a surface stress that induces MC deflection. Simulation results show that a few electrons per SWNT are needed for measureable deflections, and experimental actuators are being characterized by SEM, Raman, and an AFM optical lever system. The applied voltage is sinusoidally modulated, and deflection is measured with a lock-in amplifier. These actuators could be used for nano-manipulation, release of drugs from a capsule, or nano-valves. As a sensor, this MC/VA-SWNT system offers an improved sensitivity for chemical and bio-sensing compared to surface functionalized MC-based sensors. Those sensors only have a 2D sensing surface, but a MC/VA-SWNT system has significantly more sensing surface because the VA-SWNTs extend microns off the MC surface.

  20. A carbon nanotube wall membrane for water treatment.

    Science.gov (United States)

    Lee, Byeongho; Baek, Youngbin; Lee, Minwoo; Jeong, Dae Hong; Lee, Hong H; Yoon, Jeyong; Kim, Yong Hyup

    2015-05-14

    Various forms of carbon nanotubes have been utilized in water treatment applications. The unique characteristics of carbon nanotubes, however, have not been fully exploited for such applications. Here we exploit the characteristics and corresponding attributes of carbon nanotubes to develop a millimetre-thick ultrafiltration membrane that can provide a water permeability that approaches 30,000 l m(-2) h(-1) bar(-1), compared with the best water permeability of 2,400 l m(-2) h(-1) bar(-1) reported for carbon nanotube membranes. The developed membrane consists only of vertically aligned carbon nanotube walls that provide 6-nm-wide inner pores and 7-nm-wide outer pores that form between the walls of the carbon nanotubes when the carbon nanotube forest is densified. The experimental results reveal that the permeance increases as the pore size decreases. The carbon nanotube walls of the membrane are observed to impede bacterial adhesion and resist biofilm formation.

  1. A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

    Directory of Open Access Journals (Sweden)

    Waris Obitayo

    2012-01-01

    Full Text Available The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

  2. Methods for Gas Sensing with Single-Walled Carbon Nanotubes

    Science.gov (United States)

    Kaul, Anupama B. (Inventor)

    2013-01-01

    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  3. Release characteristics of selected carbon nanotube polymer composites

    Science.gov (United States)

    Multi-walled carbon nanotubes (MWCNTs) are commonly used in polymer formulations to improve strength, conductivity, and other attributes. A developing concern is the potential for carbon nanotube polymer nanocomposites to release nanoparticles into the environment as the polymer ...

  4. Carbon Nanotube Reinforced Polymers for Radiation Shielding Applications

    Science.gov (United States)

    Thibeault, S. (Technical Monitor); Vaidyanathan, Ranji

    2004-01-01

    This viewgraph presentation provides information on the use of Extrusion Freeform Fabrication (EEF) for the fabrication of carbon nanotubes. The presentation addresses TGA analysis, Raman spectroscopy, radiation tests, and mechanical properties of the carbon nanotubes.

  5. Physical Removal of Metallic Carbon Nanotubes from Nanotube Network Devices Using a Thermal and Fluidic Process

    OpenAIRE

    Ford, Alexandra C.; Shaughnessy, Michael; Wong, Bryan M.; Kane, Alexander A.; Kuznetsov, Oleksandr V.; Krafcik, Karen L.; Billups, W. E.; Hauge, Robert H.; Léonard, François

    2013-01-01

    Electronic and optoelectronic devices based on thin films of carbon nanotubes are currently limited by the presence of metallic nanotubes. Here we present a novel approach based on nanotube alkyl functionalization to physically remove the metallic nanotubes from such network devices. The process relies on preferential thermal desorption of the alkyls from the semiconducting nanotubes and the subsequent dissolution and selective removal of the metallic nanotubes in chloroform. The approach is ...

  6. Synergistic strengthening effect of nanocrystalline copper reinforced with carbon nanotubes.

    Science.gov (United States)

    Wang, Hu; Zhang, Zhao-Hui; Hu, Zheng-Yang; Wang, Fu-Chi; Li, Sheng-Lin; Korznikov, Elena; Zhao, Xiu-Chen; Liu, Ying; Liu, Zhen-Feng; Kang, Zhe

    2016-05-17

    In this study, a novel multi-walled carbon nanotubes reinforced nanocrystalline copper matrix composite with super high strength and moderate plasticity was synthesized. We successfully overcome the agglomeration problem of the carbon nanotubes and the grain growth problem of the nanocrystalline copper matrix by combined use of the electroless deposition and spark plasma sintering methods. The yield strength of the composite reach up to 692 MPa, which is increased by 2 and 5 times comparing with those of the nanocrystalline and coarse copper, respectively. Simultaneously, the plasticity of the composite was also significantly increased in contrast with that of the nanocrystalline copper. The increase of the density of the carbon nanotubes after coating, the isolation effect caused by the copper coating, and the improvement of the compatibility between the reinforcements and matrix as well as the effective control of the grain growth of the copper matrix all contribute to improving the mechanical properties of the composite. In addition, a new strengthening mechanism, i.e., the series-connection effect of the nanocrystalline copper grains introduced by carbon nanotubes, is proposed to further explain the mechanical behavior of the nanocomposite.

  7. Carbon Nanotube Tower-Based Supercapacitor

    Science.gov (United States)

    Meyyappan, Meyya (Inventor)

    2012-01-01

    A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

  8. Carbon Nanotube-Based Permeable Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T; Eaglesham, D

    2004-04-06

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium transport rate (for a pressure drop of 1 atm) of 0.25 cc/sec is predicted. Helium flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate greater than 1x10{sup -6} cc/sec. For viscous, laminar flow conditions, water is estimated to flow across the nanotube membrane (under a 1 atm pressure drop) at up to 2.8x10{sup -5} cc/sec (1.7 {micro}L/min).

  9. Functionalized carbon nanotubes for potential medicinal applications.

    Science.gov (United States)

    Zhang, Yi; Bai, Yuhong; Yan, Bing

    2010-06-01

    Functionalized carbon nanotubes display unique properties that enable a variety of medicinal applications, including the diagnosis and treatment of cancer, infectious diseases and central nervous system disorders, and applications in tissue engineering. These potential applications are particularly encouraged by their ability to penetrate biological membranes and relatively low toxicity. High aspect ratio, unique optical property and the likeness as small molecule make carbon nanotubes an unusual allotrope of element carbon. After functionalization, carbon nanotubes display potentials for a variety of medicinal applications, including the diagnosis and treatment of cancer, infectious diseases and central nervous system disorders, and applications in tissue engineering. These potential applications are particularly encouraged by their ability to penetrate biological membranes and relatively low toxicity.

  10. Carbon Nanotubes and Chronic Granulomatous Disease

    Directory of Open Access Journals (Sweden)

    Barbara P. Barna

    2014-06-01

    Full Text Available Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and natural gas. In experimental animal models, carbon nanotubes have been shown to induce granulomas or other inflammatory changes. Evidence suggesting potential involvement of carbon nanomaterials in human granulomatous disease, has been gathered from analyses of dusts generated in the World Trade Center disaster combined with epidemiological data showing a subsequent increase in granulomatous disease of first responders. In this review we will discuss evidence for similarities in the pathophysiology of carbon nanotube-induced pulmonary disease in experimental animals with that of the human granulomatous disease, sarcoidosis.

  11. Elastomer Reinforced with Carbon Nanotubes

    Science.gov (United States)

    Hudson, Jared L.; Krishnamoorti, Ramanan

    2009-01-01

    Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

  12. Localized Excitons in Carbon Nanotubes.

    Science.gov (United States)

    Adamska, Lyudmyla; Doorn, Stephen K.; Tretiak, Sergei

    2015-03-01

    It has been historically known that unintentional defects in carbon nanotubes (CNTs) may fully quench the fluorescence. However, some dopants may enhance the fluorescence by one order of magnitude thus turning the CNTs, which are excellent light absorbers, in good emitters. We have correlated the experimentally observed photoluminescence spectra to the electronic structure simulations. Our experiment reveals multiple sharp asymmetric emission peaks at energies 50-300 meV red-shifted from that of the lowest bright exciton peak. Our simulations suggest an association of these peaks with deep trap states tied to different specific chemical adducts. While the wave functions of excitons in undoped CNTs are delocalized, those of the deep-trap states are strongly localized and pinned to the dopants. These findings are consistent with the experimental observation of asymmetric broadening of the deep trap emission peaks, which can result from scattering of acoustic phonons on localized excitons. Our work lays the foundation to utilize doping as a generalized route for wave function engineering and direct control of carrier dynamics in SWCNTs toward enhanced light emission properties for photonic applications.

  13. Thermal Transport in Carbon Nanotubes

    Science.gov (United States)

    Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

    2011-10-01

    Recent advances in nanostructure technology have made it possible to create small devices at the nanoscale. Carbon nanotubes (CNT's) are among the most exciting building blocks of nanotechnology. Their versatility and extremely desirable properties for electronic and other devices have driven intense research and development efforts in recent years. A review of electrical and thermal conduction of the structures will be presented. The theoretical investigation is mainly based on molecular dynamics. Green Kubo relation is used for the study of thermal conductivity. Results include kinetic energy, potential energy, heat flux autocorrelation function, and heat conduction of various CNT structures. Most of the computation and simulation has been conducted on the Beowulf cluster at Ball State University. Various software packages and tools such as Visual Molecular Dynamics (VMD), Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and NanoHUB, the open online resource at Purdue University have been used for the research. The work has been supported by the Indiana Academy of Science Research Fund, 2010-2011.

  14. Different Technical Applications of Carbon Nanotubes.

    Science.gov (United States)

    Abdalla, S; Al-Marzouki, F; Al-Ghamdi, Ahmed A; Abdel-Daiem, A

    2015-12-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  15. Chemical reactions confined within carbon nanotubes.

    Science.gov (United States)

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N

    2016-08-22

    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors.

  16. Different Technical Applications of Carbon Nanotubes

    Science.gov (United States)

    Abdalla, S.; Al-Marzouki, F.; Al-Ghamdi, Ahmed A.; Abdel-Daiem, A.

    2015-09-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  17. Edge effects in finite elongated carbon nanotubes

    CERN Document Server

    Hod, O; Scuseria, G E; Hod, Oded; Peralta, Juan E.; Scuseria, Gustavo E.

    2006-01-01

    The importance of finite-size effects for the electronic structure of long zigzag and armchair carbon nanotubes is studied. We analyze the electronic structure of capped (6,6), (8,0), and (9,0) single walled carbon nanotubes as a function of their length up to 60 nm, using a divide and conquer density functional theory approach. For the metallic nanotubes studied, most of the physical features appearing in the density of states of an infinite carbon nanotube are recovered at a length of 40 nm. The (8,0) semi-conducting nanotube studied exhibits pronounced edge effects within the energy gap that scale as the inverse of the length of the nanotube. As a result, the energy gap reduces from the value of ~1 eV calculated for the periodic system to a value of ~0.25 eV calculated for a capped 62 nm long CNT. These edge effects are expected to become negligible only at tube lengths exceeding 6 micrometers. Our results indicate that careful tailoring of the nature of the system and its capping units should be applied w...

  18. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

    Science.gov (United States)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

    2013-01-01

    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  19. Chitosan-mediated synthesis of carbon nanotube-gold nanohybrids

    Institute of Scientific and Technical Information of China (English)

    GRAVEL; Edmond; FOILLARD; Stéphanie; DORIS; Eric

    2010-01-01

    Metal-nanotube nanohybrids were produced by in situ synthesis and stabilization of gold nanoparticles on chitosan-functionalized carbon nanotubes.The formation of gold nanoparticles from tetrachloroauric acid was observed after only a few minutes of contact with the functionalized nanotubes,at room temperature.These results suggest that adsorption of chitosan at the surface of carbon nanotubes permits smooth reduction of the metallic salt and efficient anchoring of gold nanoparticles to the nanotubes.

  20. Effects of single-walled carbon nanotubes on lysozyme gelation.

    Science.gov (United States)

    Tardani, Franco; La Mesa, Camillo

    2014-09-01

    The possibility to disperse carbon nanotubes in biocompatible matrices has got substantial interest from the scientific community. Along this research line, the inclusion of single walled carbon nanotubes in lysozyme-based hydrogels was investigated. Experiments were performed at different nanotube/lysozyme weight ratios. Carbon nanotubes were dispersed in protein solutions, in conditions suitable for thermal gelation. The state of the dispersions was determined before and after thermal treatment. Rheology, dynamic light scattering and different microscopies investigated the effect that carbon nanotubes exert on gelation. The gelation kinetics and changes in gelation temperature were determined. The effect of carbon and lysozyme content on the gel properties was, therefore, determined. At fixed lysozyme content, moderate amounts of carbon nanotubes do not disturb the properties of hydrogel composites. At moderately high volume fractions in carbon nanotubes, the gels become continuous in both lysozyme and nanotubes. This is because percolating networks are presumably formed. Support to the above statements comes by rheology.

  1. Deposition of the platinum crystals on the carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new technique and the affecting factors for depositing platinum on the carbon nanotubes were investigated. The results show that the deposited platinum crystals in the atmosphere of hydrogen or nitrogen have a small size and a homogeneous distribution on the surface of the carbon nanotubes. The pretreatment would decrease the platinum particles on the carbon nanotubes significantly.

  2. Transport Properties of Carbon-Nanotube/Cement Composites

    NARCIS (Netherlands)

    Han, B.; Yang, Z.; Shi, X.; Yu, X.

    2012-01-01

    This paper preliminarily investigates the general transport properties (i.e., water sorptivity, water permeability, and gas permeability) of carbon-nanotube/cement composites. Carboxyl multi-walled carbon nanotubes (MWNTs) are dispersed into cement mortar to fabricate the carbon nanotubes (CNTs) rei

  3. Preparation of carbon nanotubes with different morphology by microwave plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan); Mansurov, Zulkhair [Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Tokmoldin, S.Zh. [Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan)

    2010-04-15

    In this work we present a part of our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapour deposition MPECVD. Well aligned, curly, carbon nanosheets, coiled carbon sheets and carbon microcoils have been prepared. We have investigated the effect of the different growth condition parameters such as the growth temperature, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. The yield of the carbon microcoils was high when the growth temperature was 700 C. There is a linear relation between the growth rate and the methane to hydrogen ratio. The effect of the gas pressure on the CNTs was also studied. Our samples were investigated by scanning electron microscope and Raman spectroscopy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Multiwalled Carbon Nanotubes Decorated with Cobalt Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    D. G. Larrude

    2012-01-01

    Full Text Available Multiwalled carbon nanotubes (MWCNTs synthesized by spray pyrolysis were decorated with cobalt oxide nanoparticles using a simple synthesis route. This wet chemistry method yielded nanoparticles randomly anchored to the surface of the nanotubes by decomposition of cobalt nitrate hexahydrate diluted in acetone. Electron microscopy analysis indicated that dispersed particles were formed on the MWCNTs walls. The average size increased with the increasing concentration of cobalt nitrate in acetone in the precursor mixture. TEM images indicated that nanoparticles were strongly attached to the tube walls. The Raman spectroscopy results suggested that the MWCNT structure was slightly damaged after the nanoparticle growth.

  5. Interaction of pristine and functionalized carbon nanotubes with lipid membranes.

    Science.gov (United States)

    Baoukina, Svetlana; Monticelli, Luca; Tieleman, D Peter

    2013-10-10

    Carbon nanotubes are widely used in a growing number of applications. Their interactions with biological materials, cell membranes in particular, is of interest in applications including drug delivery and for understanding the toxicity of carbon nanotubes. We use extensive molecular dynamics simulations with the MARTINI model to study the interactions of model nanotubes of different thickness, length, and patterns of chemical modification with model membranes. In addition, we characterize the interactions of small bundles of carbon nanotubes with membrane models. Short pristine carbon nanotubes readily insert into membranes and adopt an orientation parallel to the plane of the membrane in the center of the membrane. Larger aggregates and functionalized nanotubes exhibit a range of possible interactions. The distribution and orientation of carbon nanotubes can be controlled by functionalizing the nanotubes. Free energy calculations provide thermodynamic insight into the preferred orientations of different nanotubes and quantify structural defects in the lipid matrix.

  6. Graphene-carbon nanotube hybrid materials and use as electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Tour, James M.; Zhu, Yu; Li, Lei; Yan, Zheng; Lin, Jian

    2016-09-27

    Provided are methods of making graphene-carbon nanotube hybrid materials. Such methods generally include: (1) associating a graphene film with a substrate; (2) applying a catalyst and a carbon source to the graphene film; and (3) growing carbon nanotubes on the graphene film. The grown carbon nanotubes become covalently linked to the graphene film through carbon-carbon bonds that are located at one or more junctions between the carbon nanotubes and the graphene film. In addition, the grown carbon nanotubes are in ohmic contact with the graphene film through the carbon-carbon bonds at the one or more junctions. The one or more junctions may include seven-membered carbon rings. Also provided are the formed graphene-carbon nanotube hybrid materials.

  7. Carbon nanotube suspensions, dispersions, & composites

    Science.gov (United States)

    Simmons, Trevor John

    Carbon Nanotubes (CNTs) are amazing structures that hold the potential to revolutionize many areas of scientific research. CNTs can be behave both as semiconductors and metals, can be grown in highly ordered arrays and patterns or in random orientation, and can be comprised of one graphene cylinder (single wall nanotube, SWNT) or several concentric graphene cylinders (multi-wall nanotube, MWNT). Although these structures are usually only a few nanometers wide, they can be grown up to centimeter lengths, and in massive quantities. CNTs can be produced in a variety of processes ranging from repeated combustion of organic material such as dried grass, arc-discharge with graphite electrodes, laser ablation of a graphitic target, to sophisticated chemical vapor deposition (CVD) techniques. CNTs are stronger than steel but lighter than aluminum, and can be more conductive than copper or semiconducting like silicon. This variety of properties has been matched by the wide variety of applications that have been developed for CNTs. Many of these applications have been limited by the inability of researchers to tame these structures, and incorporating CNTs into existing technologies can be exceedingly difficult and prohibitively expensive. It is therefore the aim of the current study to develop strategies for the solution processing and deposition of CNTs and CNT-composites, which will enable the use of CNTs in existing and emerging technologies. CNTs are not easily suspended in polar solvents and are extremely hydrophobic materials, which has limited much of the solution processing to organic solvents, which also cannot afford high quality dispersions of CNTs. The current study has developed a variety of aqueous CNT solutions that employ surfactants, water-soluble polymers, or both to create suspensions of CNTs. These CNT 'ink' solutions were deposited with a variety of techniques that have afforded many interesting structures, both randomly oriented as well as highly

  8. Modeling of the HiPco process for carbon nanotube production. II. Reactor-scale analysis

    Science.gov (United States)

    Gokcen, Tahir; Dateo, Christopher E.; Meyyappan, M.

    2002-01-01

    The high-pressure carbon monoxide (HiPco) process, developed at Rice University, has been reported to produce single-walled carbon nanotubes from gas-phase reactions of iron carbonyl in carbon monoxide at high pressures (10-100 atm). Computational modeling is used here to develop an understanding of the HiPco process. A detailed kinetic model of the HiPco process that includes of the precursor, decomposition metal cluster formation and growth, and carbon nanotube growth was developed in the previous article (Part I). Decomposition of precursor molecules is necessary to initiate metal cluster formation. The metal clusters serve as catalysts for carbon nanotube growth. The diameter of metal clusters and number of atoms in these clusters are some of the essential information for predicting carbon nanotube formation and growth, which is then modeled by the Boudouard reaction with metal catalysts. Based on the detailed model simulations, a reduced kinetic model was also developed in Part I for use in reactor-scale flowfield calculations. Here this reduced kinetic model is integrated with a two-dimensional axisymmetric reactor flow model to predict reactor performance. Carbon nanotube growth is examined with respect to several process variables (peripheral jet temperature, reactor pressure, and Fe(CO)5 concentration) with the use of the axisymmetric model, and the computed results are compared with existing experimental data. The model yields most of the qualitative trends observed in the experiments and helps to understanding the fundamental processes in HiPco carbon nanotube production.

  9. High frequency conductivity in carbon nanotubes

    Directory of Open Access Journals (Sweden)

    S. S. Abukari

    2012-12-01

    Full Text Available We report on theoretical analysis of high frequency conductivity in carbon nanotubes. Using the kinetic equation with constant relaxation time, an analytical expression for the complex conductivity is obtained. The real part of the complex conductivity is initially negative at zero frequency and become more negative with increasing frequency, until it reaches a resonance minimum at ω ∼ ωB for metallic zigzag CNs and ω < ωB for armchair CNs. This resonance enhancement is indicative for terahertz gain without the formation of current instabilities induced by negative dc conductivity. We noted that due to the high density of states of conduction electrons in metallic zigzag carbon nanotubes and the specific dispersion law inherent in hexagonal crystalline structure result in a uniquely high frequency conductivity than the corresponding values for metallic armchair carbon nanotubes. We suggest that this phenomenon can be used to suppress current instabilities that are normally associated with a negative dc differential conductivity.

  10. Boron-Filled Hybrid Carbon Nanotubes

    Science.gov (United States)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-07-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

  11. A review on protein functionalized carbon nanotubes.

    Science.gov (United States)

    Nagaraju, Kathyayini; Reddy, Roopa; Reddy, Narendra

    2015-12-18

    Carbon nanotubes (CNTs) have been widely recognized and used for controlled drug delivery and in various other fields due to their unique properties and distinct advantages. Both single-walled carbon nanotubes (SWCNTs) and multiwalled (MWCNTs) carbon nanotubes are used and/or studied for potential applications in medical, energy, textile, composite, and other areas. Since CNTs are chemically inert and are insoluble in water or other organic solvents, they are functionalized or modified to carry payloads or interact with biological molecules. CNTs have been preferably functionalized with proteins because CNTs are predominantly used for medical applications such as delivery of drugs, DNA and genes, and also for biosensing. Extensive studies have been conducted to understand the interactions, cytotoxicity, and potential applications of protein functionalized CNTs but contradicting results have been published on the cytotoxicity of the functionalized CNTs. This paper provides a brief review of CNTs functionalized with proteins, methods used to functionalize the CNTs, and their potential applications.

  12. Boron-Filled Hybrid Carbon Nanotubes

    Science.gov (United States)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  13. Carbon Nanotube Bolometer for Absolute FTIR Spectroscopy

    Science.gov (United States)

    Woods, Solomon; Neira, Jorge; Tomlin, Nathan; Lehman, John

    We have developed and calibrated planar electrical-substitution bolometers which employ absorbers made from vertically-aligned carbon nanotube arrays. The nearly complete absorption of light by the carbon nanotubes from the visible range to the far-infrared can be exploited to enable a device with read-out in native units equivalent to optical power. Operated at cryogenic temperatures near 4 K, these infrared detectors are designed to have time constant near 10 ms and a noise floor of about 10 pW. Built upon a micro-machined silicon platform, each device has an integrated heater and thermometer, either a carbon nanotube thermistor or superconducting transition edge sensor, for temperature control. We are optimizing temperature-controlled measurement techniques to enable high resolution spectral calibrations using these devices with a Fourier-transform spectrometer.

  14. Carbon Nanotubes Synthesis Through Gamma Radiation

    Science.gov (United States)

    Tirado, Pablo; Garcia, Rafael; Montes, Jorge; Melendrez, Rodrigo; Barboza, Marcelino; Contreras, Oscar

    2015-03-01

    Carbon nanotubes show a great potential of applications since there discovery by Iijima in 1991[1] due to their numerous physical-chemical properties such as their high weight to strength relationship, which make them ideal to use in high resistance compound materials, and in many other applications[2] In this work, a novel method for the synthesis of carbon nanotubes is presented, starting from an ultra-thin sheet of graphite synthesized by the chemical vapor decomposition technique (CVD), using ultra high purity methane and hydrogen at 1200°C in a horizontal quartz reactor. For the synthesis of carbon nanotubes, the graphite sheets were exposed to different doses of radiation, with the objective of breaking the graphite bonds and form carbon nanotubes; a Gammacell equipment model 220 Excel was used for the purpose, which counts with a radiation source of cobalt 60, and a current radiation rate of 0.9 Gy/seconds. The time of exposure to radiation was varied in each sample, according to the desired dose of radiation in each case, afterwards the samples were characterized using the Raman spectroscopy and TEM microscopy techniques with the objective of observing the kind of nanotubes formed, their morphology and their number of defects. Results will be shown during the poster session.

  15. Theoretical Descriptions of Carbon Nanotubes Synthesis in a Chemical Vapor Deposition Reactor: A Review

    OpenAIRE

    Lubej, M.; Plazl, I.

    2012-01-01

    The mechanisms by which carbon nanotubes nucleate and grow are still poorly understood. Understanding and mathematically describing the process is crucial for its optimization. This paper reviews different models which have been proposed to explain carbon nanotube growth in the chemical vapor deposition process. The review is divided into two sections, the first section describes some nucleation, growth and termination simulations based on molecular dynamics, and the second section describes ...

  16. A carbon nanotube optical rectenna

    Science.gov (United States)

    Sharma, Asha; Singh, Virendra; Bougher, Thomas L.; Cola, Baratunde A.

    2015-12-01

    An optical rectenna—a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current—was first proposed over 40 years ago, yet this concept has not been demonstrated experimentally due to fabrication challenges at the nanoscale. Realizing an optical rectenna requires that an antenna be coupled to a diode that operates on the order of 1 PHz (switching speed on the order of 1 fs). Diodes operating at these frequencies are feasible if their capacitance is on the order of a few attofarads, but they remain extremely difficult to fabricate and to reliably couple to a nanoscale antenna. Here we demonstrate an optical rectenna by engineering metal-insulator-metal tunnel diodes, with a junction capacitance of ˜2 aF, at the tip of vertically aligned multiwalled carbon nanotubes (˜10 nm in diameter), which act as the antenna. Upon irradiation with visible and infrared light, we measure a d.c. open-circuit voltage and a short-circuit current that appear to be due to a rectification process (we account for a very small but quantifiable contribution from thermal effects). In contrast to recent reports of photodetection based on hot electron decay in a plasmonic nanoscale antenna, a coherent optical antenna field appears to be rectified directly in our devices, consistent with rectenna theory. Finally, power rectification is observed under simulated solar illumination, and there is no detectable change in diode performance after numerous current-voltage scans between 5 and 77 °C, indicating a potential for robust operation.

  17. Micromechanics of carbon nanotube turfs

    Science.gov (United States)

    Torabi, Hamid

    Complex structures consisting of intertwined, nominally vertical carbon nanotubes (CNTs) are called turfs. Unique electrical, thermal, optical, and permeability properties of these turfs have attracted growing attention during the past decade, and have rendered them as appropriate candidates for applications such as contact thermal switches. These properties are controlled by the details of the turf microstructures. Due to the application of the turfs in different fields, they are subjected to different loading conditions. Deformation changes the microstructure of a CNT turf, which results in change of effective properties. Many researchers have recently studied the collective mechanical behavior of CNT turfs to compression loading, as this behavior determines their performance. However, their complex and intertwined structure must be investigated in more details to find the relation between their deformation and their underlying morphology. Under uniform compression experiments, CNT turfs exhibit irreversible collective buckling of a layer preceded by reorientation of CNT segments. Experimentally observed independence of the buckling stress and the buckling wavelength on the turf width suggests the existence of an intrinsic material length. To investigate the relationship the macroscopic material properties and the statistical parameters describing the nano-scale geometry of the turf (tortuosity, density and connectivity) we develop a nano-scale computational model, based on the representation of CNT segments as elastica finite elements with van der Waals interactions. The virtual turfs are generated by means of a constrained random walk algorithm and subsequent relaxation. The resulting computational model is robust and is capable of modeling the collective behavior of CNTs. We first establish the dependence of statistical parameters on the computational parameters used for turf generation, then establish relationships between post-buckling stress, initial

  18. Structural and biological properties of carbon nanotube composite films

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Roger J. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)]. E-mail: roger.narayan@mse.gatech.edu; Berry, C.J. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States); Brigmon, R.L. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States)

    2005-11-20

    Carbon nanotube composite films have been developed that exhibit unusual structural and biological properties. These novel materials have been created by pulsed laser ablation of graphite and bombardment of nitrogen ions at temperatures between 600 and 700 deg. C. High-resolution transmission electron microscopy and radial distribution function analysis demonstrate that this material consists of sp{sup 2}-bonded concentric ribbons that are wrapped approximately 15 deg. normal to the silicon substrate. The interlayer order in this material extends to approximately 15-30 A. X-ray photoelectron spectroscopy and Raman spectroscopy data suggest that this material is predominantly trigonally coordinated. The carbon nanotube composite structure results from the use of energetic ions, which allow for non-equilibrium growth of graphitic planes. In vitro testing has revealed significant antimicrobial activity of carbon nanotube composite films against Staphylococcus aureus and Staphylococcus warneri colonization. Carbon nanotube composite films may be useful for inhibiting microorganism attachment and biofilm formation in hemodialysis catheters and other medical devices.

  19. Laser ablative synthesis of carbon nanotubes

    Science.gov (United States)

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2010-03-02

    An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.

  20. Carbon nanotubes for in vivo cancer nanotechnology

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The latest progress of using carbon nanotubes(CNTs) for in vivo cancer nanotechnology is reviewed.CNTs can be functionalized by either covalent or non-covalent chemistry to produce functional bioconjugates for many in vivo applications.In vivo behaviors and toxicology studies of CNTs are summarized,suggesting no significant toxicity of well functionalized CNTs to the treated mice.Owing to their unique chemical and physical properties,CNTs,especially single-walled carbon nanotubes(SWNTs),have been widely used for various modalities of in vivo cancer treatment and imaging.Future development of CNT-based nanomedicine may bring novel opportunities to cancer diagnosis and therapy.

  1. Piezoresistive effect in carbon nanotube films

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The piezoresistive effect of the pristine carbon nanotube (CNT) films has been studied. Carbon nanotubes were synthesized by hot filament chemical vapor deposition. The piezoresistive effect in the pristine CNT films was studied by a three-point bending test. The gauge factor for the pristine CNT films under 500 microstrains was found to be at least 65 at room temperature, and increased with temperature, exceeding that of polycrystalline silicon (30) at 35℃. The origin of the piezoresistivity in CNT films may be ascribed to a pressure-induced change in the band gap and the defects.

  2. Nanoscale atomic waveguides with suspended carbon nanotubes

    CERN Document Server

    Peano, V; Kasper, A; Egger, R

    2005-01-01

    We propose an experimentally viable setup for the realization of one-dimensional ultracold atom gases in a nanoscale magnetic waveguide formed by single doubly-clamped suspended carbon nanotubes. We show that all common decoherence and atom loss mechanisms are small guaranteeing a stable operation of the trap. Since the extremely large current densities in carbon nanotubes are spatially homogeneous, our proposed architecture allows to overcome the problem of fragmentation of the atom cloud. Adding a second nanowire allows to create a double-well potential with a moderate tunneling barrier which is desired for tunneling and interference experiments with the advantage of tunneling distances being in the nanometer regime.

  3. Carbon nanotube based transparent conductive thin films.

    Science.gov (United States)

    Yu, X; Rajamani, R; Stelson, K A; Cui, T

    2006-07-01

    Carbon nanotube (CNT) based optically transparent and electrically conductive thin films are fabricated on plastic substrates in this study. Single-walled carbon nanotubes (SWNTs) are chemically treated with a mixture of concentrated sulfuric acid and nitric acid before being dispersed in aqueous surfactant-contained solutions. SWNT thin films are prepared from the stable SWNT solutions using wet coating techniques. The 100 nm thick SWNT thin film exhibits a surface resistivity of 6 kohms/square nanometer with an average transmittance of 88% on the visible light range, which is three times better than the films prepared from the high purity as-received SWNTs.

  4. Are carbon nanotubes a natural solution? Applications in biology and medicine.

    Science.gov (United States)

    Heister, Elena; Brunner, Eric W; Dieckmann, Gregg R; Jurewicz, Izabela; Dalton, Alan B

    2013-03-01

    Carbon nanotubes and materials based on carbon nanotubes have many perceived applications in the field of biomedicine. Several highly promising examples have been highlighted in the literature, ranging from their use as growth substrates or tissue scaffolds to acting as intracellular transporters for various therapeutic and diagnostic agents. In addition, carbon nanotubes have a strong optical absorption in the near-infrared region (in which tissue is transparent), which enables their use for biological imaging applications and photothermal ablation of tumors. Although these advances are potentially game-changing, excitement must be tempered somewhat as several bottlenecks exist. Carbon nanotube-based technologies ultimately have to compete with and out-perform existing technologies in terms of performance and price. Moreover, issues have been highlighted relating to toxicity, which presents an obstacle for the transition from preclinical to clinical use. Although many studies have suggested that well-functionalized carbon nanotubes appear to be safe to the treated animals, mainly rodents, long-term toxicity issues remains to be elucidated. In this report, we systematically highlight some of the most promising biomedical application areas of carbon nanotubes and review the interaction of carbon nanotubes with cultured cells and living organisms with a particular focus on in vivo biodistribution and potential adverse health effects. To conclude, future challenges and prospects of carbon nanotubes for biomedical applications will be addressed.

  5. Quantum transport in carbon nanotubes

    DEFF Research Database (Denmark)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.;

    2015-01-01

    by recent advances in theory. As well as the well-understood overall picture, we also state clearly open questions for the field. These advances position nanotubes as a leading system for the study of spin and valley physics in one dimension where electronic disorder and hyperfine interaction can both...... and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and from valley freedom. We focus on the interplay between the two....... In single quantum dots defined in short lengths of nanotube, the energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are revealed by Coulomb blockade spectroscopy. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli...

  6. A tunable carbon nanotube electromechanical oscillator

    Science.gov (United States)

    Sazonova, Vera; Yaish, Yuval; Üstünel, Hande; Roundy, David; Arias, Tomás A.; McEuen, Paul L.

    2004-09-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. In particular, NEMS oscillators have been proposed for use in ultrasensitive mass detection, radio-frequency signal processing, and as a model system for exploring quantum phenomena in macroscopic systems. Perhaps the ultimate material for these applications is a carbon nanotube. They are the stiffest material known, have low density, ultrasmall cross-sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus may be able to sense its own motion. In spite of this great promise, a room-temperature, self-detecting nanotube oscillator has not been realized, although some progress has been made. Here we report the electrical actuation and detection of the guitar-string-like oscillation modes of doubly clamped nanotube oscillators. We show that the resonance frequency can be widely tuned and that the devices can be used to transduce very small forces.

  7. Shear Flow Induced Alignment of Carbon Nanotubes in Natural Rubber

    Directory of Open Access Journals (Sweden)

    Yan He

    2015-01-01

    Full Text Available A new procedure for the fabrication of natural rubber composite with aligned carbon nanotubes is provided in this study. The two-step approach is based on (i the preparation of mixture latex of natural rubber, multiwalled carbon nanotubes, and other components and (ii the orientation of carbon nanotubes by a flow field. Rubber composite sheets filled with variable volume fraction of aligned carbon nanotubes were fabricated and then confirmed by transmission electron microscopy and Raman spectroscopy studies. An obvious increase in thermal conductivity has been obtained after the alignment of carbon nanotubes. The dynamic mechanical analysis was carried out in a tear mode for the composite.

  8. Carbon nanotubes as tips for atomic force microscopy

    Institute of Scientific and Technical Information of China (English)

    国立秋; 徐宗伟; 赵铁强; 赵清亮; 张飞虎; 董申

    2004-01-01

    Ordinary AFM probes' characters prevent the AFM' s application in various scopes. Carbon nanotubes represent ideal AFM probe materials for their higher aspect ratio, larger Young' s modulus, unique chemical structure, and well-defined electronic property. Carbon nanotube AFM probes are obtained by using a new method of attaching carbon nanotubes to the end of ordinary AFM probes, and are then used for doing AFM experiments. These experiments indicated that carbon nanotube probes have higher elastic deformation, higher resolution and higher durability. And it was also found that carbon nanotube probes can accurately reflect the morphology of deep narrow gaps, while ordinary probes can not reflect.

  9. Computational Nanomechanics of Carbon Nanotubes and Composites

    Science.gov (United States)

    Srivastava, Deepak; Wei, Chenyu; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

    2002-01-01

    Nanomechanics of individual carbon and boron-nitride nanotubes and their application as reinforcing fibers in polymer composites has been reviewed with interplay of theoretical modeling, computer simulations and experimental observations. The emphasis in this work is on elucidating the multi-length scales of the problems involved, and of different simulation techniques that are needed to address specific characteristics of individual nanotubes and nanotube polymer-matrix interfaces. Classical molecular dynamics simulations are shown to be sufficient to describe the generic behavior such as strength and stiffness modulus but are inadequate to describe elastic limit and nature of plastic buckling at large strength. Quantum molecular dynamics simulations are shown to bring out explicit atomic nature dependent behavior of these nanoscale materials objects that are not accessible either via continuum mechanics based descriptions or through classical molecular dynamics based simulations. As examples, we discus local plastic collapse of carbon nanotubes under axial compression and anisotropic plastic buckling of boron-nitride nanotubes. Dependence of the yield strain on the strain rate is addressed through temperature dependent simulations, a transition-state-theory based model of the strain as a function of strain rate and simulation temperature is presented, and in all cases extensive comparisons are made with experimental observations. Mechanical properties of nanotube-polymer composite materials are simulated with diverse nanotube-polymer interface structures (with van der Waals interaction). The atomistic mechanisms of the interface toughening for optimal load transfer through recycling, high-thermal expansion and diffusion coefficient composite formation above glass transition temperature, and enhancement of Young's modulus on addition of nanotubes to polymer are discussed and compared with experimental observations.

  10. Graphene/single-walled carbon nanotube hybrids: one-step catalytic growth and applications for high-rate Li-S batteries.

    Science.gov (United States)

    Zhao, Meng-Qiang; Liu, Xiao-Fei; Zhang, Qiang; Tian, Gui-Li; Huang, Jia-Qi; Zhu, Wancheng; Wei, Fei

    2012-12-21

    The theoretically proposed graphene/single-walled carbon nanotube (G/SWCNT) hybrids by placing SWCNTs among graphene planes through covalent C-C bonding are expected to have extraordinary physical properties and promising engineering applications. However, the G/CNT hybrids that have been fabricated differ greatly from the proposed G/SWCNT hybrids because either the covalent C-C bonding is not well constructed or only multiwalled CNTs/carbon nanofibers rather than SWCNTs are available in the hybrids. Herein, a novel G/SWCNT hybrid was successfully fabricated by a facile catalytic growth on layered double hydroxide (LDH) at a high temperature over 950 °C. The thermally stable Fe nanoparticles and the uniform structure of the calcined LDH flakes are essential for the simultaneously catalytic deposition of SWCNTs and graphene. The SWCNTs and the CVD-grown graphene, as well as the robust connection between the SWCNTs and graphene, facilitated the construction of a high electrical conductive pathway. The internal spaces between the two stacked graphene layers and among SWCNTs offer room for sulfur storage. Therefore, the as obtained G/SWCNT-S cathode exhibited excellent performance in Li-S batteries with a capacity as high as 650 mAh g(-1) after 100 cycles even at a high current rate of 5 C. Such a novel G/SWCNT hybrid can serve not only as a prototype to shed light on the chemical principle of G/CNT synthesis but also as a platform for their further applications in the area of nanocomposites, heterogeneous catalysis, drug delivery, electrochemical energy storage, and so on.

  11. Preparation of Carbon Nanotubes from Methane on Ni/Cu/A1 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Renzhong Wei; Fengyi Li; Yan Ju

    2005-01-01

    A series of Ni/Cu/Al catalyst samples were prepared by the co-precipitation method. Carbon nanotubes with large inner diameters are successfully synthesized from methane on Ni/Cu/Al catalyst by adding sodium carbonate. The effects of the copper content and amounts of sodium carbonate on the morphology and microstructures of carbon nanotubes were investigated by CO adsorption and TEM technique. The experimental results showed that copper can influence both the catalytic activity and catalyst life. Best result was obtained when the copper content was 15%. Addition of sodium carbonate favors the formation of carbon nanotubes with large inner diameters. The growth mechanism of carbon nanotubes with large inner diameter is discussed.

  12. Nickel oxide nanotube synthesis using multiwalled carbon nanotubes as sacrificial templates for supercapacitor application

    Science.gov (United States)

    Abdalla, Ahmed M.; Sahu, Rakesh P.; Wallar, Cameron J.; Chen, Ri; Zhitomirsky, Igor; Puri, Ishwar K.

    2017-02-01

    A novel approach for the fabrication of nickel oxide nanotubes based on multiwalled carbon nanotubes as a sacrificial template is described. Electroless deposition is employed to deposit nickel onto carbon nanotubes. The subsequent annealing of the product in the presence of air oxidizes nickel to nickel oxide, and carbon is released as gaseous carbon dioxide, leaving behind nickel oxide nanotubes. Electron microscopy and elemental mapping confirm the formation of nickel oxide nanotubes. New chelating polyelectrolytes are used as dispersing agents to achieve high colloidal stability for both the nickel-coated carbon nanotubes and the nickel oxide nanotubes. A gravimetric specific capacitance of 245.3 F g-1 and an areal capacitance of 3.28 F cm-2 at a scan rate of 2 mV s-1 is achieved, with an electrode fabricated using nickel oxide nanotubes as the active element with a mass loading of 24.1 mg cm-2.

  13. Coal-derived carbon nanotubes by thermal plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Y.; Zhang, Y.L.; Wang, B.J.; Ji, W.J.; Zhang, Y.F.; Xie, K.C. [Nanjing University, Nanjing (China). Dept. of Physics

    2004-07-01

    A coal/arc-jet technique by directly and successively injecting coal fine particles into the arc plasma jet instead of arcing graphite or coal-based electrodes for producing carbon nanotubes (CNTs) from coal was developed. The derived carbon products by this technique were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), high-resolution TEM (HRTEM), X-ray energy dispersive spectrum (EDS), X-ray diffraction (XRD) and Raman spectrum. The experimental results clearly indicated that certain metal catalysts favored the growth of CNTs in the process, and the relevant growth mechanism was discussed in terms of the characterizations.

  14. Flexible microdevices based on carbon nanotubes

    Science.gov (United States)

    Allen, Ashante'; Cannon, Andrew; Lee, Jungchul; King, William P.; Graham, Samuel

    2006-12-01

    This work reports the fabrication and testing of flexible carbon nanotube microdevices made using hot embossing material transfer. Both micro-plasma and photodetector devices were made using as-grown unpurified multi-wall carbon nanotubes printed on PMMA substrates. Optical detectors were fabricated by attaching metal wires and monitoring the resistance as a function of light exposure. The electrical resistance of the nanotubes showed a strong sensitivity to light exposure which was also enhanced by heating the devices. While such processes in MWCNTs are not fully understood, the addition of thermal energy is believed to generate additional free charge carriers in the nanotubes. The plasma-generating microdevices consisted of a thin layer of thermoplastic polymer having the CNT electrode on one side and a metal electrode on the reverse side. The devices were electrically tested under atmospheric conditions with 0.01-1 kV ac and at 2.5 kHz, with the plasma igniting near 0.7 kV. The fabrication of these flexible organic devices demonstrates the ability to pattern useful carbon nanotube microdevices in low-cost thermoplastic polymers.

  15. Carbon nanotubes as optical biomedical sensors.

    Science.gov (United States)

    Kruss, Sebastian; Hilmer, Andrew J; Zhang, Jingqing; Reuel, Nigel F; Mu, Bin; Strano, Michael S

    2013-12-01

    Biosensors are important tools in biomedical research. Moreover, they are becoming an essential part of modern healthcare. In the future, biosensor development will become even more crucial due to the demand for personalized-medicine, point-of care devices and cheaper diagnostic tools. Substantial advances in sensor technology are often fueled by the advent of new materials. Therefore, nanomaterials have motivated a large body of research and such materials have been implemented into biosensor devices. Among these new materials carbon nanotubes (CNTs) are especially promising building blocks for biosensors due to their unique electronic and optical properties. Carbon nanotubes are rolled-up cylinders of carbon monolayers (graphene). They can be chemically modified in such a way that biologically relevant molecules can be detected with high sensitivity and selectivity. In this review article we will discuss how carbon nanotubes can be used to create biosensors. We review the latest advancements of optical carbon nanotube based biosensors with a special focus on near-infrared (NIR)-fluorescence, Raman-scattering and fluorescence quenching.

  16. Carbon Nanotube Membranes: Carbon Nanotube Membranes for Energy-Efficient Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-03-01

    Broad Funding Opportunity Announcement Project: Porifera is developing carbon nanotube membranes that allow more efficient removal of CO2 from coal plant exhaust. Most of today’s carbon capture methods use chemical solvents, but capture methods that use membranes to draw CO2 out of exhaust gas are potentially more efficient and cost effective. Traditionally, membranes are limited by the rate at which they allow gas to flow through them and the amount of CO2 they can attract from the gas. Smooth support pores and the unique structure of Porifera’s carbon nanotube membranes allows them to be more permeable than other polymeric membranes, yet still selective enough for CO2 removal. This approach could overcome the barriers facing membrane-based approaches for capturing CO2 from coal plant exhausts.

  17. A Study of Surface Modifications of Carbon Nanotubes on the Properties of Polyamide 66/Multiwalled Carbon Nanotube Composites

    Directory of Open Access Journals (Sweden)

    Li Qiu

    2013-01-01

    Full Text Available The effects of surface modification of carbon nanotube on the properties of polyamide 66/multiwalled carbon nanotube composites have been investigated. Polyamide 66 (PA66 and multiwalled carbon nanotube (MWCNT composites were prepared by melt mixing. The surfaces of MWCNTs were modified with acid- and amine-groups. Field emission scanning electron microscopy analyses revealed that amine-MWCNTs (D-MWCNTs dispersed better in the PA66 matrix than pristine- and acid-MWCNTs. However, an introduction of D-MWCNTs into PA66 matrix induced heterogeneous nucleation and affected the crystal growth process during the crystallization of PA66/MWCNT composites. Both nanoindentation and friction analyses were carried out in a study of the effect of the introduction of modified MWCNTs on both mechanical and friction properties of the composites. With the introduction of D-MWCNTs, both nanohardness and elastic modulus of the composites were significantly improved, but it was observed that the maximum depth, nanohardness, and elastic modulus of the composites showed no distinct change before and after a friction test. It is evident that PA66/D-MWCNT composites have the least friction coefficient of the PA66/MWCNT composites of all the approaches of carbon nanotube surface modification.

  18. Interfacing carbon nanotubes (CNT) with plants: enhancement of growth, water and ionic nutrient uptake in maize ( Zea mays) and implications for nanoagriculture

    Science.gov (United States)

    Tiwari, D. K.; Dasgupta-Schubert, N.; Villaseñor Cendejas, L. M.; Villegas, J.; Carreto Montoya, L.; Borjas García, S. E.

    2014-06-01

    The application of nano-biotechnology to crop-science/agriculture (`nanoagriculture') is a recent development. While carbon nanotubes (CNTs) have been shown to dramatically improve germination of some comestible plants, deficiencies in consistency of behavior and reproducibility arise, partially from the variability of the CNTs used. In this work, factory-synthesized multi-walled-CNTs (MWCNTs) of quality-controlled specifications were seen to enhance the germinative growth of maize seedlings at low concentrations but depress it at higher concentrations. Growth enhancement principally arose through improved water delivery by the MWCNT. Polarized EDXRF spectrometry showed that MWCNTs affect mineral nutrient supply to the seedling through the action of the mutually opposing forces of inflow with water and retention in the medium by the ion-CNT transient-dipole interaction. The effect varied with ion type and MWCNT concentration. The differences of the Fe tissue concentrations when relatively high equimolar Fe2+ or Fe3+ was introduced, implied that the ion-CNT interaction might induce redox changes to the ion. The tissue Ca2+ concentration manifested as the antipode of the Fe2+ concentration indicating a possible cationic exchange in the cell wall matrix. SEM images showed that MWCNTs perforated the black-layer seed-coat that could explain the enhanced water delivery. The absence of perforations with the introduction of FeCl2/FeCl3 reinforces the idea of the modification of MWCNT functionality by the ion-CNT interaction. Overall, in normal media, low dose MWCNTs were seen to be beneficial, improving water absorption, plant biomass and the concentrations of the essential Ca, Fe nutrients, opening a potential for possible future commercial agricultural applications.

  19. Roll-to-Roll production of carbon nanotubes based supercapacitors

    Science.gov (United States)

    Zhu, Jingyi; Childress, Anthony; Karakaya, Mehmet; Roberts, Mark; Arcilla-Velez, Margarita; Podila, Ramakrishna; Rao, Apparao

    2014-03-01

    Carbon nanomaterials provide an excellent platform for electrochemical double layer capacitors (EDLCs). However, current industrial methods for producing carbon nanotubes are expensive and thereby increase the costs of energy storage to more than 10 Wh/kg. In this regard, we developed a facile roll-to-roll production technology for scalable manufacturing of multi-walled carbon nanotubes (MWNTs) with variable density on run-of-the-mill kitchen Al foils. Our method produces MWNTs with diameter (heights) between 50-100 nm (10-100 μm), and a specific capacitance as high as ~ 100 F/g in non-aqueous electrolytes. In this talk, the fundamental challenges involved in EDLC-suitable MWNT growth, roll-to-roll production, and device manufacturing will be discussed along with electrochemical characteristics of roll-to-roll MWNTs. Research supported by NSF CMMI Grant1246800.

  20. Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake

    OpenAIRE

    Miralles, Pola; Johnson, Errin; Tamara L. Church; Harris, Andrew T.

    2012-01-01

    Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l−1 CNTs, and root elongation was enhanced in alfalfa and wh...

  1. Carbon nanotubes for thermal interface materials in microelectronic packaging

    Science.gov (United States)

    Lin, Wei

    As the integration scale of transistors/devices in a chip/system keeps increasing, effective cooling has become more and more important in microelectronics. To address the thermal dissipation issue, one important solution is to develop thermal interface materials with higher performance. Carbon nanotubes, given their high intrinsic thermal and mechanical properties, and their high thermal and chemical stabilities, have received extensive attention from both academia and industry as a candidate for high-performance thermal interface materials. The thesis is devoted to addressing some challenges related to the potential application of carbon nanotubes as thermal interface materials in microelectronics. These challenges include: 1) controlled synthesis of vertically aligned carbon nanotubes on various bulk substrates via chemical vapor deposition and the fundamental understanding involved; 2) development of a scalable annealing process to improve the intrinsic properties of synthesized carbon nanotubes; 3) development of a state-of-art assembling process to effectively implement high-quality vertically aligned carbon nanotubes into a flip-chip assembly; 4) a reliable thermal measurement of intrinsic thermal transport property of vertically aligned carbon nanotube films; 5) improvement of interfacial thermal transport between carbon nanotubes and other materials. The major achievements are summarized. 1. Based on the fundamental understanding of catalytic chemical vapor deposition processes and the growth mechanism of carbon nanotube, fast synthesis of high-quality vertically aligned carbon nanotubes on various bulk substrates (e.g., copper, quartz, silicon, aluminum oxide, etc.) has been successfully achieved. The synthesis of vertically aligned carbon nanotubes on the bulk copper substrate by the thermal chemical vapor deposition process has set a world record. In order to functionalize the synthesized carbon nanotubes while maintaining their good vertical alignment

  2. Structure Stability of Ⅰ-Type Carbon Nanotube Junctions

    Institute of Scientific and Technical Information of China (English)

    夏丹; 袁喆; 李家明

    2002-01-01

    Carbon nanotubes with junctions may play an important role in future ‘nanoelectronics' and future ‘nano devices'.In particular, junctions constructed with metal and semiconducting nanotubes have potential applications. Basedon the orthogonal tight-binding molecular dynamics method, we present our study of the structure stability ofI-type carbon nanotube junctions.

  3. Advanced materials based on carbon nanotube arrays, yarns and papers

    Science.gov (United States)

    Bradford, Phlip David

    Carbon nanotubes have hundreds of potential applications but require innovative processing techniques to manipulate the microscopic carbon dust into useful devices and products. This thesis describes efforts to process carbon nanotubes (CNTs) using novel methods with the goals of: (1) improving the properties of energy absorbing and composite carbon nanotube materials and (2) increasing understanding of fundamental structure-property relationships within these materials. Millimeter long CNTs, in the form of arrays, yarns and papers, were used to produce energy absorbing foams and high volume fraction CNT composites. Vertically aligned CNT arrays were grown on silicon substrates using chemical vapor deposition (CVD) of ethylene gas over iron nano-particles. The low density, millimeter thick arrays were tested under compression as energy absorbing foams. With additional CVD processing steps, it was possible to tune the compressive properties of the arrays. After the longest treatment, the compressive strength of the arrays was increased by a factor of 35 with a density increase of only six fold, while also imparting recovery from compression to the array. Microscopy revealed that the post-synthesis CVD treatment increased the number of CNT walls through an epitaxial type radial growth on the surface of the as-grown tubes. The increase in tube radius and mutual support between nanotubes explained the increases in compressive strength while an increase in nanotube roughness was proposed as the morphological change responsible for recovery in the array. Carbon nanotube yarns were used as the raw material for macroscopic textile preforms with a multi-level hierarchical carbon nanotube (CNT) structure: nanotubes, bundles, spun single yarns, plied yarns and 3-D braids. In prior tensile tests, composites produced from the 3-D braids exhibited unusual mechanical behavior effects. The proposed physical hypotheses explained those effects by molecular level interactions and

  4. Bioaccumulation and ecotoxicity of carbon nanotubes

    DEFF Research Database (Denmark)

    Jackson, Petra; Jacobsen, Nicklas Raun; Baun, Anders;

    2013-01-01

    Carbon nanotubes (CNT) have numerous industrial applications and may be released to the environment. In the aquatic environment, pristine or functionalized CNT have different dispersion behavior, potentially leading to different risks of exposure along the water column. Data included in this review...

  5. Effective models for excitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Cornean, Horia; Duclos, Pierre; Ricaud, Benjamin

    2007-01-01

    We analyse the low lying spectrum of a model of excitons in carbon nanotubes. Consider two particles with opposite charges and a Coulomb self-interaction, placed on an infinitely long cylinder. If the cylinder radius becomes small, the low lying spectrum of their relative motion is well described...

  6. Effective models for excitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Cornean, Horia; Duclos, Pierre; Ricaud, Benjamin

    We analyse the low lying spectrum of a model of excitons in carbon nanotubes. Consider two particles with a Coulomb self-interaction, placed on an infinitely long cylinder. If the cylinder radius becomes small, the low lying spectrum is well described by a one-dimensional effective Hamiltonian...

  7. In-line manufacture of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Brambilla, Nicol Michele; Signorelli, Riccardo; Martini, Fabrizio; Corripio Luna, Oscar Enrique

    2015-04-28

    Mass production of carbon nanotubes (CNT) are facilitated by methods and apparatus disclosed herein. Advantageously, the methods and apparatus make use of a single production unit, and therefore provide for uninterrupted progress in a fabrication process. Embodiments of control systems for a variety of CNT production apparatus are included.

  8. Biodistribution of Carbon Nanotubes in Animal Models

    DEFF Research Database (Denmark)

    Jacobsen, Nicklas Raun; Møller, Peter; Clausen, Per Axel

    2016-01-01

    The many physical and chemical properties of carbon nanotubes (CNT) make it one of the most commercially attractive materials in the era of nanotechnology. Here, we review the recent publications on in vivo biodistribution of pristine and functionalized forms of single-walled and multi-walled CNT...

  9. Conductance of AFM Deformed Carbon Nanotubes

    Science.gov (United States)

    Svizhenko, Alexei; Maiti, Amitesh; Anatram, M. P.; Biegel, Bryan (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on the electrical conductivity of carbon nanotubes upon deformation by atomic force microscopy (AFM). The density of states and conductance were computed using four orbital tight-binding method with various parameterizations. Different chiralities develop bandgap that varies with chirality.

  10. Multiwall carbon nanotubes reinforced epoxy nanocomposites

    Science.gov (United States)

    Chen, Wei

    The emergence of carbon nanotubes (CNTs) has led to myriad possibilities for structural polymer composites with superior specific modulus, strength, and toughness. While the research activities in carbon nanotube reinforced polymer composites (NRPs) have made enormous progress towards fabricating next-generation advanced structural materials with added thermal, optical, and electrical advantages, questions concerning the filler dispersion, interface, and CNT alignment in these composites remain partially addressed. In this dissertation, the key technical challenges related to the synthesis, processing, and reinforcing mechanics governing the effective mechanical properties of NRPs were introduced and reviewed in the first two chapters. Subsequently, issues on the dispersion, interface control, hierarchical structure, and multi-functionality of NRPs were addressed based on functionalized multi-walled carbon nanotube reinforced DGEBA epoxy systems (NREs). In chapter 3, NREs with enhanced flexural properties were discussed in the context of improved dispersion and in-situ formation of covalent bonds at the interface. In chapter 4, NREs with controlled interface and tailored thermomechanical properties were demonstrated through the judicious choice of surface functionality and resin chemistry. In chapter 5, processing-condition-induced CNT organization in hierarchical epoxy nanocomposites was analyzed. In Chapter 6, possibilities were explored for multi-functional NREs for underwater acoustic structural applications. Finally, the findings of this dissertation were concluded and future research was proposed for ordered carbon nanotube array reinforced nanocomposites in the last chapter. Four journal publications resulted from this work are listed in Appendix.

  11. Spatially resolved spectroscopy on carbon nanotubes

    NARCIS (Netherlands)

    Janssen, J.W.

    2001-01-01

    Carbon nanotubes are small cylindrical molecules with a typical diameter of 1 nm and lengths of up to micrometers. These intriguing molecules exhibit, depending on the exact atomic structure, either semiconducting or metallic behavior. This makes them ideal candidates for possible future molecular e

  12. Chemistry of Carbon Nanotubes for Everyone

    Science.gov (United States)

    Basu-Dutt, Sharmistha; Minus, Marilyn L.; Jain, Rahul; Nepal, Dhriti; Kumar, Satish

    2012-01-01

    Carbon nanotubes (CNTs) have the extraordinary potential to change our lives by improving existing products and enabling new ones. Current and future research and industrial workforce professionals are very likely to encounter some aspects of nanotechnology including CNT science and technology in their education or profession. The simple structure…

  13. Single electron-ics with carbon nanotubes

    NARCIS (Netherlands)

    Götz, G.T.J.

    2010-01-01

    We experimentally investigate Quantum Dots, formed in Carbon Nanotubes. The first part of this thesis deals with charge sensing on such quantum dots. The charge sensor is a metallic Single-electron-transistor, sensitive to the charge of a single electron on the quantum dot. We use this technique for

  14. Photothermal effects of immunologically modified carbon nanotubes

    Science.gov (United States)

    Griswold, Ryan T.; Henderson, Brock; Goddard, Jessica; Tan, Yongqiang; Hode, Tomas; Liu, Hong; Nordquist, Robert E.; Chen, Wei R.

    2013-02-01

    Carbon nanotubes have a great potential in the biomedical applications. To use carbon nanotubes in the treatment of cancer, we synthesized an immunologically modified single-walled carbon nanotube (SWNT) using a novel immunomodifier, glycated chitosan (GC), as an effective surfactant for SWNT. This new composition SWNT-GC was stable due to the strong non-covalent binding between SWNT and GC. The structure of SWNT-GC is presented in this report. The photothermal effect of SWNT-GC was investigated under irradiation of a near-infrared laser. SWNT-GC retained the optical properties of SWNT and the immunological properties of GC. Specifically, the SWNT-GC could selectively absorb a 980-nm light and induce desirable thermal effects in tissue culture and in animals. It could also induce tumor cell destruction, controlled by the laser settings and the doses of SWNT and GC. Laser+SWNT-GC treatment could also induce strong expression of heat shock proteins on the surface of tumor cells. This immunologically modified carbon nanotube could be used for selective photothermal interactions in noninvasive tumor treatment.

  15. A New Resistance Formulation for Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Ji-Huan He

    2008-01-01

    Full Text Available A new resistance formulation for carbon nanotubes is suggested using fractal approach. The new formulation is also valid for other nonmetal conductors including nerve fibers, conductive polymers, and molecular wires. Our theoretical prediction agrees well with experimental observation.

  16. Field emission properties of the graphenated carbon nanotube electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zanin, H., E-mail: hudson.zanin@bristol.ac.uk [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Faculdade de Engenharia Elétrica e Computação, Departamento de Semicondutores, Instrumentos e Fotônica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N. 400, CEP 13 083-852 Campinas, São Paulo (Brazil); Ceragioli, H.J.; Peterlevitz, A.C.; Baranauskas, Vitor [Faculdade de Engenharia Elétrica e Computação, Departamento de Semicondutores, Instrumentos e Fotônica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N. 400, CEP 13 083-852 Campinas, São Paulo (Brazil); Marciano, F.R.; Lobo, A.O. [Laboratory of Biomedical Nanotechnology/Institute of Research and Development at UNIVAP, Av. Shishima Hifumi, 2911, CEP 12244-000 Sao Jose dos Campos, SP (Brazil)

    2015-01-01

    Graphical abstract: - Highlights: • Facile method to prepare graphenated carbon nanotubes (g-CNTs). • The electric field emission behaviour of g-CNTs was studied. • g-CNTs show better emission current stability than non-graphenated CNTs. - Abstract: Reduced graphene oxide-coated carbon nanotubes (RGO-CNT) electrodes have been prepared by hot filament chemical vapour deposition system in one-step growth process. We studied RGO-CNT electrodes behaviour as cold cathode in field emission test. Our results show that RGO-CNT retain the low threshold voltage typical of CNTs, but with greatly improved emission current stability. The field emission enhancement value is significantly higher than that expected being caused by geometric effect (height divided by the radius of nanotube). This suggested that the field emission of this hybrid structure is not only from a single tip, but eventually it is from several tips with contribution of graphene nanosheets at CNT's walls. This phenomenon explains why the graphenated carbon nanotubes do not burn out as quickly as CNT does until emission ceases completely. These preliminaries results make nanocarbon materials good candidates for applications as electron sources for several devices.

  17. Quantum transport in carbon nanotubes

    DEFF Research Database (Denmark)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.

    2015-01-01

    modifies their transport behaviour. Interaction between electrons inside and outside a quantum dot is manifested in SU(4) Kondo behavior and level renormalization. Interaction within a dot leads to Wigner molecules and more complex correlated states. This review takes an experimental perspective informed...... and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and from valley freedom. We focus on the interplay between the two....... In single quantum dots defined in short lengths of nanotube, the energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are revealed by Coulomb blockade spectroscopy. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli...

  18. Making junctions between carbon nanotubes using an ion beam

    CERN Document Server

    Krasheninnikov, A V; Keinonen, J; Banhart, F

    2003-01-01

    Making use of empirical potential molecular dynamics, we study ion bombardment of crossed single-walled carbon nanotubes as a tool to join the nanotubes. We demonstrate that ion irradiation should result in welding of crossed nanotubes, both suspended and deposited on substrates. We further predict optimum ion doses and energies for ion-mediated nanotube welding which may potentially be used for developing complicated networks of joined nanotubes.

  19. Carbon nanotubes for stem cell control

    Directory of Open Access Journals (Sweden)

    David A. Stout

    2012-07-01

    Full Text Available In the past decade, two major advancements have transformed the world of tissue engineering and regenerative medicine—stem cells and carbon nano-dimensional materials. In the past, stem cell therapy seemed like it may present a cure for all medical ailments, but problems arose (i.e., immune system clearance, control of differentiation in the body, etc. that have hindered progress. But, with the synergy of carbon nano-dimensional materials, researchers have been able to overcome these tissue engineering and regenerative medicine obstacles and have begun developing treatments for strokes, bone failure, cardiovascular disease, and many other conditions. Here, we briefly review research involving carbon nanotubes which are relevant to the tissue engineering and regenerative medicine field with a special emphasis on carbon nanotube applications for stem cell delivery, drug delivery applications, and their use as improved medical devices.

  20. Pure carbon nanoscale devices: Nanotube heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Chico, L.; Crespi, V.H.; Benedict, L.X.; Louie, S.G.; Cohen, M.L. [Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States)]|[Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

    1996-02-01

    Introduction of pentagon-heptagon pair defects into the hexagonal network of a single carbon nanotube can change the helicity of the tube and alter its electronic structure. Using a tight-binding method to calculate the electronic structure of such systems we show that they behave as nanoscale metal/semiconductor or semiconductor/semiconductor junctions. These junctions could be the building blocks of nanoscale electronic devices made entirely of carbon. {copyright} {ital 1996 The American Physical Society.}

  1. Exploring the Immunotoxicity of Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yu Yanmei

    2008-01-01

    Full Text Available Abstract Mass production of carbon nanotubes (CNTs and their applications in nanomedicine lead to the increased exposure risk of nanomaterials to human beings. Although reports on toxicity of nanomaterials are rapidly growing, there is still a lack of knowledge on the potential toxicity of such materials to immune systems. This article reviews some existing studies assessing carbon nanotubes’ toxicity to immune system and provides the potential mechanistic explanation.

  2. Preparation of double-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    JIANG Bin; WEI Jinquan; CI Lijie; WU Dehai

    2004-01-01

    Double-walled carbon nanotubes were prepared using the floating chemical vapor deposition with methane as carbon source and adding small amount of sulfur into the ferrocene catalyst. The optimized technological parameters are: the reaction temperature is 1200℃; the catalyst vapor temperature is 80℃; the flow rate of argon is 2000 SCCM; the flow rate of methane is 5 SCCM. The purified DWNTs under these optimized technological parameters have high purity above 90 wt%.

  3. Three-dimensional helical carbon materials: Microcoiled carbon fibers, carbon nanocoils, carbon nanotubes: Synthesis, properties and applications

    Science.gov (United States)

    Xie, Jining

    . Due to their extraordinary properties, carbon nanotubes have been expected to have wide applications. Efforts have been made on the synthesis of high quality carbon nanotubes economically in this work. A novel catalyst/catalyst support pair, iron/magnesium carbonate, has been developed for synthesis of multi-walled carbon nanotubes with high purity. The coil morphology is induced by insertion of pentagon-heptagon pairs into hexagonal network of nanotube wall periodically. Thorough purification of carbon nanotubes is always a concern before investigating their properties and potential applications. Impurities in raw carbon nanotube material have to be removed by chemical treatment. A couple of purification methods are presented in this work. Various techniques have been used to characterize these micro- and nano-3D materials, such as scanning electron microscopy (SEM), energy dispersive spectrum (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer Emmett-Teller (BET), thermal gravimetric analysis (TGA), etc. Growth mechanisms are proposed based on the experimental and characterization results. It is verified that the nonuniform carbon deposition rate on catalyst particles leads to the bending of the carbon fiber/tubule, and hence results in the coil morphology. To conclude, the research work reported here is a systematic study on synthesis, characterizations, and applications of micro- and nano-3D helical carbon materials, such as micro coiled carbon fibers, carbon nanocoils and carbon nanotubes. A few suggestions for future research directions are also listed.

  4. Electrochemical production of Sn-filled carbon nanotubes in molten salts

    Institute of Scientific and Technical Information of China (English)

    黄辉; 张文魁; 李美超; 甘永平; 马淳安; 张孝彬

    2004-01-01

    Sn-filled carbon nanotubes(CNTs) were prepared in situ by electrolysis of graphite in molten LiCl/SnCl2mixtures. Transmission electron microscopy(TEM) investigation shows that the as-made products contain abundance of carbon nanotubes and most of them are filled with metal nanoparticles or nanorods. Some nanotubes are even inserted with long continuous nanowires more than several micrometers in length. Selected area electron diffraction(SAED) patterns and energy dispersive X-ray spectroscopy(EDS) of the filled nanotubes confirm the presence ofSn inside the nanotubes. The encapsulated Sn was further identified asβ-Sn with tetragonal structure. Based on theexperimental results, a possible growth mechanism of the Sn-filled nanotubes was also discussed.

  5. Carbon nanotube oscillators for applications as nanothermometers

    Science.gov (United States)

    Rahmat, Fainida; Thamwattana, Ngamta; Hill, James M.

    2010-10-01

    Nanostructures such as carbon nanotubes have a broad range of potential applications such as nanomotors, nano-oscillators and electromechanical nanothermometers, and a proper understanding of the molecular interaction between nanostructures is fundamentally important for these applications. In this paper, we determine the molecular interaction potential of interacting carbon nanotubes for two configurations. The first is a shuttle configuration involving a short outer tube sliding on a fixed inner tube, and the second involves a telescopic configuration for which an inner tube moves both in the region between two outer tubes and through the tubes themselves. For the first configuration we examine two cases of semi-infinite and finite inner carbon nanotubes. We employ the continuum approximation and the 6-12 Lennard-Jones potential for non-bonded molecules to determine the molecular interaction potential and the resulting van der Waals force, and we evaluate the resulting surface integrals numerically. We also investigate the acceptance condition and suction energy for the first configuration. Our results show that for the shuttle configuration with a semi-infinite inner tube, the suction energy is maximum when the difference between the outer and inner tubes radii is approximately 3.4 Å, which is the ideal inter-wall spacing between graphene sheets. For the finite inner tube, the potential energy is dependent on both the inner and outer tube lengths as well as on the inter-wall spacing. In terms of the oscillating frequency, the critical issue is the length of the moving outer tube, and the shorter the length, the higher the frequency. Further, for the telescopic configuration with two semi-infinite outer nanotubes of different radii, we find that the interaction energy also depends on the difference of the tube radii. For two outer nanotubes of equal radii we observe that the shorter the distance between the two outer nanotubes, the higher the magnitude of the

  6. Role of Reaction and Factors of Carbon Nanotubes Growth in Chemical Vapour Decomposition Process Using Methane—A Highlight

    Directory of Open Access Journals (Sweden)

    Sivakumar VM

    2010-01-01

    This paper reviewed the synthesis of CNT by CVD especially focusing on methane CVD. Various parameters influencing the reaction and CNT growth were also discussed. A detailed review was made over the different types of CVD process, influence of metal, supports, metal-support interaction, effect of promoters, and reaction parameters role in CNTs growth.

  7. Production of Carbon Nanotubes over Pre-reduced LaCoO3 by Using Fluidized-bed Catalytic Reactor

    Institute of Scientific and Technical Information of China (English)

    刘宝春; 唐水花; 梁奇; 高利珍; 张伯兰; 瞿美臻; 于作龙

    2001-01-01

    A technique has been developed to grow carbon nanotubes by flowing acetylene over pre-reduced LaCoO3 catalyst in a fluidized- bed catalytic reactor. Carbon nanotubes were characterized by means of SEM and TEM. The pre-reduced LaCoO3catalyst was found to be effective in producing carbon nanotubes with even diameter. The effects of reduction temperature of LaCoO3 on the growth of carbon nanotubes were investigated. This process can easily be scaled up.

  8. Controlled carbon nanotube synthesis for quantification of polymer-nanotube composite micromechanics

    Science.gov (United States)

    Bult, Justin Bernard

    Conventional experimental approaches to the understanding of nanotube-polymer micro-mechanics have struggled to produce reproducible data due to the inherent difficulty in physically manipulating the nanotube in-situ. To avoid the problems scale represents in nanotube-polymer composites a novel approach of using Polarized Raman spectroscopy was developed. The Raman spectroscopic technique has the advantage of using non-invasive analysis to compute the composite micro mechanical properties of interfacial shear stress and critical length. Composites with nanotubes of defined length were needed in order to use the Raman technique. To satisfy this requirement a new thermal Chemical Vapor Deposition (CVD) tool capable of reproducibly growing aligned length uniformity with large mass yield was designed and built. The course of developing these furnace capabilities led to the investigation of nanotube growth mechanics. It is shown herein that a stable passivation barrier is required for nanotube growth. Using X-Ray Photoelectron Spectroscopy (XPS) depth profiling of metal substrate growth conclusively shows the presence of a stable catalyst layer on the outer surface of stable oxides of greater than 100 nm. By analyzing the diffusion profile represented in the XPS data it is shown that a critical thickness for the passivation oxide can be calculated as a function of time and temperature. For the growth parameters used in this study the critical thickness was found to be between 10 nm and 30 nm depending on the diffusivity value used for iron in chromia. This value agrees well with experimental observation. Uniformly grown carbon nanotubes with lengths of 4, 14, 17, 22, 43, 74, and 116 mum were incorporated into a polycarbonate matrix polymer via solvent-antisolvent processing. The nanotube composites of varied length were tested in tensile strain while Raman spectra were taken concurrently to deduce the load transfer to the nanotube due to composite strain. It is found

  9. Field-effect transistors assembled from functionalized carbon nanotubes

    OpenAIRE

    Klinke, Christian; Hannon, James B.; Afzali, Ali; Avouris, Phaedon

    2006-01-01

    We have fabricated field effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Upon annealing, the functionalization is removed, restoring the electronic properties of the nanotubes. The devices we have fabricated show excellent electrical characteristics.

  10. Porous carbon nanotubes: Molecular absorption, transport, and separation

    Science.gov (United States)

    Yzeiri, Irena; Patra, Niladri; Král, Petr

    2014-03-01

    We use classical molecular dynamics simulations to study nanofluidic properties of porous carbon nanotubes. We show that saturated water vapor condenses on the porous nanotubes, can be absorbed by them and transported in their interior. When these nanotubes are charged and placed in ionic solutions, they can selectively absorb ions in their interior and transport them. Porous carbon nanotubes can also be used as selective molecular sieves, as illustrated on a room temperature separation of benzene and ethanol.

  11. Carbon nanotubes on a spider silk scaffold

    Science.gov (United States)

    Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

    2013-09-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations.

  12. Localization in single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Fuhrer, M.S.; Cohen, M.L.; Zettl, A.; Crespi, V.H.

    1998-08-15

    We demonstrate that in low temperature semiconductor-like regions the electrical resistance of single-walled carbon nanotube mats is highly nonlinear with a temperature-dependent threshold field for the onset of nonohmic conduction. The modest applied electric field completely suppresses the upturn in resistance and recovers metallic behavior over the entire temperature range 2.2K < T < 300K. The transport data indicate low-temperature localization of charge carriers arise from disorder on the nanotube bundles themselves and not from granularity caused by weak interbundle connections. The temperature-independent localization radius a is determined to be approximately 330 nm.

  13. Extraordinary improvement of the graphitic structure of continuous carbon nanofibers templated with double wall carbon nanotubes.

    Science.gov (United States)

    Papkov, Dimitry; Beese, Allison M; Goponenko, Alexander; Zou, Yan; Naraghi, Mohammad; Espinosa, Horacio D; Saha, Biswajit; Schatz, George C; Moravsky, Alexander; Loutfy, Raouf; Nguyen, Sonbinh T; Dzenis, Yuris

    2013-01-22

    Carbon nanotubes are being widely studied as a reinforcing element in high-performance composites and fibers at high volume fractions. However, problems with nanotube processing, alignment, and non-optimal stress transfer between the nanotubes and surrounding matrix have so far prevented full utilization of their superb mechanical properties in composites. Here, we present an alternative use of carbon nanotubes, at a very small concentration, as a templating agent for the formation of graphitic structure in fibers. Continuous carbon nanofibers (CNF) were manufactured by electrospinning from polyacrylonitrile (PAN) with 1.2% of double wall nanotubes (DWNT). Nanofibers were oxidized and carbonized at temperatures from 600 °C to 1850 °C. Structural analyses revealed significant improvements in graphitic structure and crystal orientation in the templated CNFs, with the largest improvements observed at lower carbonization temperatures. In situ pull-out experiments showed good interfacial bonding between the DWNT bundles and the surrounding templated carbon matrix. Molecular Dynamics (MD) simulations of templated carbonization confirmed oriented graphitic growth and provided insight into mechanisms of carbonization initiation. The obtained results indicate that global templating of the graphitic structure in fine CNFs can be achieved at very small concentrations of well-dispersed DWNTs. The outcomes reveal a simple and inexpensive route to manufacture continuous CNFs with improved structure and properties for a variety of mechanical and functional applications. The demonstrated improvement of graphitic order at low carbonization temperatures in the absence of stretch shows potential as a promising new manufacturing technology for next generation carbon fibers.

  14. A new method of preparing single-walled carbon nanotubes

    OpenAIRE

    Vivekchang, SRC; Govindaraj, A.

    2003-01-01

    A novel method of purification for single-walled carbon nanotubes, prepared by an arc-discharge method, is described. The method involves a combination of acid washing followed by high temperature hydrogen treatment to remove the metal nanoparticles and amorphous carbon present in the as-synthesized single-walled carbon nanotubes. The purified single-walled carbon nanotubes have been characterised by low-angle X-ray diffraction, electron microscopy, thermo-gravimetric analysis and Raman spect...

  15. Carbon Nanotubes Hybrid Hydrogels in Drug Delivery: A Perspective Review

    OpenAIRE

    Giuseppe Cirillo; Silke Hampel; Umile Gianfranco Spizzirri; Ortensia Ilaria Parisi; Nevio Picci; Francesca Iemma

    2014-01-01

    The use of biologics, polymers, silicon materials, carbon materials, and metals has been proposed for the preparation of innovative drug delivery devices. One of the most promising materials in this field are the carbon-nanotubes composites and hybrid materials coupling the advantages of polymers (biocompatibility and biodegradability) with those of carbon nanotubes (cellular uptake, stability, electromagnatic, and magnetic behavior). The applicability of polymer-carbon nanotubes composites i...

  16. A new method of preparing single-walled carbon nanotubes

    Indian Academy of Sciences (India)

    S R C Vivekchand; A Govindaraj

    2003-10-01

    A novel method of purification for single-walled carbon nanotubes, prepared by an arc-discharge method, is described. The method involves a combination of acid washing followed by high temperature hydrogen treatment to remove the metal nanoparticles and amorphous carbon present in the as-synthesized singlewalled carbon nanotubes. The purified single-walled carbon nanotubes have been characterised by low-angle X-ray diffraction, electron microscopy, thermo-gravimetric analysis and Raman spectroscopy.

  17. Modification of multi-walled carbon nanotubes by plasma treatment and further use as templates for growth of CdS nanocrystals.

    Science.gov (United States)

    Tseng, Chun-Hao; Wang, Cheng-Chien; Chen, Chuh-Yung

    2006-11-28

    In this study, we present a novel method for preparing multi-walled carbon nanotubes (MWCNTs) grafted with a poly(2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester) (GMA-IDA)-cadmium sulfide complex (CNTs-G-ICdS complex) through plasma-induced grafting polymerization. The characteristics of the MWCNTs after being grafted with the GMA-IDA polymer were monitored by a Fourier transform infrared (FT-IR) spectroscope. Scanning electronic microscopy (SEM) shows that the amount of GMA-IDA grafted onto the MWCNTs increases with the concentration of GMA-IDA monomer. The complex resulting from GMA-IDA polymer grafting onto the MWCNTs, CNTs-G-I (15%), shows excellent dispersion properties in aqueous solution and has high Zeta potential values over a wide range of pH values, from 2 to 12. Moreover, Raman spectroscopy was used to confirm the successful chemical modification of MWCNTs through the plasma treatment. The chelating groups, -N(CH(2)COO(-))(2) in the GMA-IDA polymer grafted on the surface of the CNTs-G-I, are the coordination sites for chelating cadmium ions, and are further used as nano-templates for the growth of CdS nanocrystals (quantum dots). Moreover, TEM microscopy reveals that the size of the CdS nanocrystals on the CNT surfaces increases with increasing S(2-) concentration. In addition, high resolution x-ray photoelectron (XPS) spectroscopy was used to characterize the functional groups on the surface of the MWCNTs after chemical modification by the plasma treatment and grafting with GMA-IDA polymer.

  18. Thin Coatings of Polymeric Carbon and Carbon Nanotubes for Corrosion Protection

    Science.gov (United States)

    2009-02-01

    Carbon Nanotube Functionalization /Doping Polyvinylpyrrolidone (PVP) A) p-Doping C) Polymer Wrapping Model B) n-Doping Polyethyleneimine ( PEI ) SWCNT Paint...fluorine-containing) groups functions as the barrier layer Multilayer Smart Carbon Nanotube Coating Insoluble polymer layer top coating -PMMA Substrate...Thin Coatings of Polymeric Carbon and Carbon Nanotubes for Corrosion Protection Zafar Iqbal Department of Chemistry and Environmental Science New

  19. Functionalization of vertically aligned carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Eloise Van Hooijdonk

    2013-02-01

    Full Text Available This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs. The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs.

  20. Carbon nanotubes degraded by neutrophil myeloperoxidase induce less pulmonary inflammation

    Science.gov (United States)

    Kagan, Valerian E.; Konduru, Nagarjun V.; Feng, Weihong; Allen, Brett L.; Conroy, Jennifer; Volkov, Yuri; Vlasova, Irina I.; Belikova, Natalia A.; Yanamala, Naveena; Kapralov, Alexander; Tyurina, Yulia Y.; Shi, Jingwen; Kisin, Elena R.; Murray, Ashley R.; Franks, Jonathan; Stolz, Donna; Gou, Pingping; Klein-Seetharaman, Judith; Fadeel, Bengt; Star, Alexander; Shvedova, Anna A.

    2010-05-01

    We have shown previously that single-walled carbon nanotubes can be catalytically biodegraded over several weeks by the plant-derived enzyme, horseradish peroxidase. However, whether peroxidase intermediates generated inside human cells or biofluids are involved in the biodegradation of carbon nanotubes has not been explored. Here, we show that hypochlorite and reactive radical intermediates of the human neutrophil enzyme myeloperoxidase catalyse the biodegradation of single-walled carbon nanotubes in vitro, in neutrophils and to a lesser degree in macrophages. Molecular modelling suggests that interactions of basic amino acids of the enzyme with the carboxyls on the carbon nanotubes position the nanotubes near the catalytic site. Importantly, the biodegraded nanotubes do not generate an inflammatory response when aspirated into the lungs of mice. Our findings suggest that the extent to which carbon nanotubes are biodegraded may be a major determinant of the scale and severity of the associated inflammatory responses in exposed individuals.

  1. Adsorption of Gases on Carbon Nanotubes

    Science.gov (United States)

    Mbaye, Mamadou Thiao

    2014-01-01

    This research focus in studying the interaction between various classical and quantum gases with novel carbon nanostructures, mainly carbon nanotubes (CNTs). Since their discovery by the Japanese physicist Sumio Iijima [1] carbon nanotubes have, experimentally and theoretically, been subjected to many scientific investigation. Studies of adsorption on CNTs are particularly directed toward their better usage in gas storage, gas separation, catalyst, drug delivery, and water purification. We explore the adsorption of different gases entrapped in a single, double, or multi-bundles of CNTs using computer simulations. The first system we investigate consists of Ar and Kr films adsorbed on zigzag or armchair nanotubes. Our simulations revealed that Kr atoms on intermediate size zigzag NTs undergo two phase transitions: A liquid-vapor (L→V), and liquid-commensurate (L→CS) with a fractional coverage of one Kr atoms adsorbed for every four carbon atoms. For Ar on zigzag and armchair NTs, the only transition observed is a L→V. In the second problem, we explore the adsorption of CO2 molecules in a nanotube bundle and calculate the isosteric heat of adsorption of the entrapped molecules within the groove. We observed that the lower the temperature, the higher the isosteric of adsorption. Last, we investigate the adsorption of hydrogen, Helium, and Neon gases on the groove site of two parallel nanotubes. At low temperature, the transverse motion on the plane perpendicular to the tubes' axis is frozen out and as a consequence, the heat capacity is reduced to 1/2. At high temperature, the atoms gain more degree of freedom and as a consequence the heat capacity is 5/2.

  2. Purification of Carbon Nanotubes by Proton Irradiation

    Science.gov (United States)

    Kim, Euikwoun; Lee, Jeonggil; Lee, Younman; Jeon, Jaekyun; Kim, Jae-Yong; Kim, Jeongha; Shin, Kwanwoo; Youn, Sang-Pil; Kim, Kyeryung

    2007-10-01

    Carbon nanotubes (CNTs) exhibit variety of superior physical properties including well-defined nanodimensional structure, high electrical and thermal conductivity, and good mechanical stability against external irradiations. Further, a large specific surface area per unit weight suggests that carbon nanotubes could be excellent candidates for gas storage, purification, and separation. However, the practical application of CNTs is limited mainly due to the metallic impurities that were used as a catalyst during the fabrication process. Here, we irradiated CNTs by using high energy proton beams (35.7 MeV at the Bragg Peak). Interestingly, metallic impurities such as Fe, Ni, Co and chunk of amorphous carbon that were attached on the surface of CNTs were completely removed after the irradiation. The mechanism of such the purification process is not understood. The possible speculation will be demonstrated combined with the changes of physical properties including the appearance of the magnetism after the irradiation.

  3. Mechanical properties of functionalized carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z Q; Liu, B; Chen, Y L; Hwang, K C [FML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Jiang, H [Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, AZ 85287 (United States); Huang, Y [Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208 (United States)], E-mail: liubin@tsinghua.edu.cn, E-mail: y-huang@northwestern.edu

    2008-10-01

    Carbon nanotubes (CNTs) used to reinforce polymer matrix composites are functionalized to form covalent bonds with the polymer in order to enhance the CNT/polymer interfaces. These bonds destroy the perfect atomic structures of a CNT and degrade its mechanical properties. We use atomistic simulations to study the effect of hydrogenization on the mechanical properties of single-wall carbon nanotubes. The elastic modulus of CNTs gradually decreases with the increasing functionalization (percentage of C-H bonds). However, both the strength and ductility drop sharply at a small percentage of functionalization, reflecting their sensitivity to C-H bonds. The cluster C-H bonds forming two rings leads to a significant reduction in the strength and ductility. The effect of carbonization has essentially the same effect as hydrogenization.

  4. On the Nanoindentation of the Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Petre P. Teodorescu

    2010-01-01

    Full Text Available A new inverse approach is proposed in this paper, which combines elements of nonlocal theory and molecular mechanics, based on the experimental results available in the nanoindentation literature. The effect of the inlayer van der Waals atomistic interactions for carbon nanotubes with multiple walls (MWCNT is included by means of the Brenner-Tersoff potential and experimental results. The neighboring walls of MWCNT are coupled through van der Waals interactions, and the shell buckling would initiate in the outermost shell, when nanotubes are short. The nanoindentation technique is simulated for the axially compressed of individual nanotubes, in order to evaluate the load-unloaded-displacement, the curve critical buckling and the appropriate values for local Lamé constants.

  5. A Carbon Arc Apparatus For Production Of Nanotubes In Microgravity

    Science.gov (United States)

    Alford, J. M.; Mason, G. R.; Feikema, D. A.

    2003-01-01

    Although many methods are available for production of single-walled carbon nanotubes (SWNTs), the conventional carbon arc process remains the most popular due to its simplicity and large production rate. However, high temperatures inside the carbon arc generate strong buoyancy driven convection, and it is hypothesized that the non-uniform environment created by this flow will have large effects on the growth and morphology of SWNTs produced by the arc process. Indeed, using normal gravity experiments, Marin et al. have demonstrated that changes in the buoyant convection plume produced by altering the arc electrode orientation can be used to change the diameter distribution of the SWNTs produced; an effect they attribute to changes in the temperature of the local nanotube growth environment. While these experiments present convincing evidence that buoyant convection has a strong effect on nanotube growth, normal gravity experiments are severely limited in scope. The ideal way to study the effect of buoyancy on SWNT production is to remove it completely. Toward this goal, a microgravity carbon arc reactor has been designed for use in the NASA Glenn 2.2 and 5 second drop towers. Although simple in principle, conventional carbon arc machines, which generally employ large reaction chambers and require heavy duty welding power supplies capable of supplying kilowatts of power, are not suitable for microgravity experiments. Here we describe a miniature carbon arc machine for SWNT production that fits into a conventional drop rig for use on the NASA Glenn 2.2 and 5 second drop towers, but that has a performance (production rate) that is better than most large ground-based machines.

  6. A Spray Pyrolysis Method to Grow Carbon Nanotubes on Carbon Fibres, Steel and Ceramic Bricks.

    Science.gov (United States)

    Vilatela, Juan J; Rabanal, M E; Cervantes-Sodi, Felipe; García-Ruiz, Máximo; Jiménez-Rodríguez, José A; Reiband, Gerd; Terrones, Mauricio

    2015-04-01

    We demonstrate a spray pyrolysis method to grow carbon nanotubes (CNTs) with high degree of crystallinity, aspect ratio and degree of alignment on a variety of different substrates, such as conventional steel, carbon fibres (CF) and ceramics. The process consists in the chemical vapour deposition of both a thin SiO2 layer and CNTs that subsequently grow on this thin layer. After CNT growth, increases in specific surface by factors of 1000 and 30 for the steel and CF samples, respectively, are observed. CNTs growth on ceramic surfaces results in a surface resistance of 37.5 Ohm/sq. When using conventional steel as a rector tube, we observed CNTs growth rates of 0.6 g/min. Details of nanotube morphology and the growth mechanism are discussed. Since the method discussed here is highly versatile, it opens up a wide variety of applications in which specific substrates could be used in combination with CNTs.

  7. Bamboo and herringbone shaped carbon nanotubes and carbon nanofibres synthesized in direct current-plasma enhanced chemical vapour deposition.

    Science.gov (United States)

    Zhang, Lu; Chen, Li; Wells, Torquil; El-Gomati, Mohamed

    2009-07-01

    Carbon nanotubes with different structures were catalytically synthesized on Ni coated SiO2/Si substrate in a Direct Current Plasma Enhanced Chemical Vapour Deposition system, in which C2H2 acted as the carbon source and NH3 as the etchant gas. A Scanning Electron Microscope study showed that carbon nanotubes were all vertically aligned with respect to the substrate, with diameters ranging from 10 nm to 200 nm. Different sizes of Ni catalyst particles were observed on the tips of carbon nanotubes. Transmission Electron Microscopy was used to study the morphology of the grown tubes and the results obtained show that the diameters and structures of these carbon nanotubes were closely correlated to the sizes and structures of the Ni nanoparticles. Two main structures namely bamboo shaped carbon nanotubes and herringbone shaped carbon nanofibres were found on the same sample. It is suggested that by controlling the pre-growth condition, desired structure of carbon nanotubes or carbon nanofibres could be produced for practical applications.

  8. Carbon Nanotubes for Space Photovoltaic Applications

    Science.gov (United States)

    Efstathiadis, Harry; Haldar, Pradeep; Landi, Brian J.; Denno, Patrick L.; DiLeo, Roberta A.; VanDerveer, William; Raffaelle, Ryne P.

    2007-01-01

    Carbon nanotubes (CNTs) can be envisioned as an individual graphene sheet rolled into a seamless cylinder (single-walled, SWNT), or concentric sheets as in the case of a multi-walled carbon nanotube (MWNT) (1). The role-up vector will determine the hexagonal arrangement and "chirality" of the graphene sheet, which will establish the nanotube to be metallic or semiconducting. The optoelectronic properties will depend directly on this chiral angle and the diameter of the SWNT, with semiconductor types exhibiting a band gap energy (2). Characteristic of MWNTs are the concentric graphene layers spaced 0.34 nm apart, with diameters from 10-200 nm and lengths up to hundreds of microns (2). In the case of SWNTs, the diameters range from 0.4 - 2 nm and lengths have been reported up to 1.5 cm (3). SWNTs have the distinguishable property of "bundling" together due to van der Waal's attractions to form "ropes." A comparison of these different structural types is shown in Figure 1. The use of SWNTS in space photovoltaic (PV) applications is attractive for a variety of reasons. Carbon nanotubes as a class of materials exhibit unprecedented optical, electrical, mechanical properties, with the added benefit of being nanoscale in size which fosters ideal interaction in nanomaterial-based devices like polymeric solar cells. The optical bandgap of semiconducting SWNTs can be varied from approx. 0.4 - 1.5 eV, with this property being inversely proportional to the nanotube diameter. Recent work at GE Global Research has shown where a single nanotube device can behave as an "ideal" pn diode (5). The SWNT was bridged over a SiO2 channel between Mo contacts and exhibited an ideality factor of 1, based on a fit of the current-voltage data using the diode equation. The measured PV efficiency under a 0.8 eV monochromatic illumination showed a power conversion efficiency of 0.2 %. However, the projected efficiency of these junctions is estimated to be > 5 %, especially when one considers the

  9. Multifunctional Carbon Nanotube Fiber Composites

    Science.gov (United States)

    2007-11-02

    coagulant. The second process (patent pending) is novel in that it directly results polymer-free nanotube fibers without using a super acid spinning...chemical and electrochemical stability, hydrophobicity and viscosity . The generic structure, chemical name and abbreviations for the most common ions...modification procedure involved the electrochemical infiltration of small amounts of the polypyrrole/p-toluene sulphonate (PPy/PTS) conducting polymer

  10. Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon

    Science.gov (United States)

    Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.

    2012-01-01

    The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.

  11. Metal-enhanced fluorescence of carbon nanotubes.

    Science.gov (United States)

    Hong, Guosong; Tabakman, Scott M; Welsher, Kevin; Wang, Hailiang; Wang, Xinran; Dai, Hongjie

    2010-11-17

    The photoluminescence (PL) quantum yield of single-walled carbon nanotubes (SWNTs) is relatively low, with various quenching effects by metallic species reported in the literature. Here, we report the first case of metal enhanced fluorescence (MEF) of surfactant-coated carbon nanotubes on nanostructured gold substrates. The photoluminescence quantum yield of SWNTs is observed to be enhanced more than 10-fold. The dependence of fluorescence enhancement on metal-nanotube distance and on the surface plasmon resonance (SPR) of the gold substrate for various SWNT chiralities is measured to reveal the mechanism of enhancement. Surfactant-coated SWNTs in direct contact with metal exhibit strong MEF without quenching, suggesting a small quenching distance for SWNTs on the order of the van der Waals distance, beyond which the intrinsically fast nonradiative decay rate in nanotubes is little enhanced by metal. The metal enhanced fluorescence of SWNTs is attributed to radiative lifetime shortening through resonance coupling of SWNT emission to the reradiating dipolar plasmonic modes in the metal.

  12. Spectroscopy of Optical Excitations in Carbon Nanotubes

    Science.gov (United States)

    Ma, Yingzhong

    2006-03-01

    Understanding the optical spectra and electronic excited state dynamics of carbon naotubes is important both for fundamental research and a wide variety of potential applications. In this presentation, we will report the results of a systematic study on semiconducting single-walled carbon nanotubes (SWNTs) obtained by utilizing complementary femtosecond spectroscopic techniques, including fluorescence up-conversion, frequency-resolved transient absorption, and three-pulse photon echo peakshift (3PEPS) spectroscopy. Our efforts have focused on optically selective detection of the spectra and dynamics associated with structurally distinct semiconducting SWNT species. Using individual nanotube enriched micelle-dispersed SWNT preparations, in combination with resonant excitation and detection, has enabled us to independently access selected species, such as the (8,3), (6,5), (7,5), (11,0), (7,6) and (9,5) nanotubes. We will discuss the following topics: (1) the excitonic nature of the elementary excitation and its unambiguous identification from direct determination of the exciton binding energy for a selected semiconducting nanotube, the (8,3) tube; (2) the spectroscopic and dynamical signatures of exciton-exciton annihilation and its predominant role in governing ultrafast excited state relaxation; (3) the annihilation-concomitant exciton dissociation and the spectroscopic and dynamic features of the resulting electron-hole continuum; (4) timescales characterizing the ultrafast thermalization processes. In addition, we will demonstrate the power of 3PEPS spectroscopy to elucidate the spectral properties and dynamics of SWNTs. This work was supported by the NSF.

  13. Developing Carbon Nanotube Standards at NASA

    Science.gov (United States)

    Nikolaev, Pasha; Arepalli, Sivaram; Sosa, Edward; Gorelik, Olga; Yowell, Leonard

    2007-01-01

    Single wall carbon nanotubes (SWCNTs) are currently being produced and processed by several methods. Many researchers are continuously modifying existing methods and developing new methods to incorporate carbon nanotubes into other materials and utilize the phenomenal properties of SWCNTs. These applications require availability of SWCNTs with known properties and there is a need to characterize these materials in a consistent manner. In order to monitor such progress, it is critical to establish a means by which to define the quality of SWCNT material and develop characterization standards to evaluate of nanotube quality across the board. Such characterization standards should be applicable to as-produced materials as well as processed SWCNT materials. In order to address this issue, NASA Johnson Space Center has developed a protocol for purity and dispersion characterization of SWCNTs. The NASA JSC group is currently working with NIST, ANSI and ISO to establish purity and dispersion standards for SWCNT material. A practice guide for nanotube characterization is being developed in cooperation with NIST. Furthermore, work is in progress to incorporate additional characterization methods for electrical, mechanical, thermal, optical and other properties of SWCNTs.

  14. Remote Joule heating by a carbon nanotube

    Science.gov (United States)

    Baloch, Kamal H.; Voskanian, Norvik; Bronsgeest, Merijntje; Cumings, John

    2012-05-01

    Minimizing Joule heating remains an important goal in the design of electronic devices. The prevailing model of Joule heating relies on a simple semiclassical picture in which electrons collide with the atoms of a conductor, generating heat locally and only in regions of non-zero current density, and this model has been supported by most experiments. Recently, however, it has been predicted that electric currents in graphene and carbon nanotubes can couple to the vibrational modes of a neighbouring material, heating it remotely. Here, we use in situ electron thermal microscopy to detect the remote Joule heating of a silicon nitride substrate by a single multiwalled carbon nanotube. At least 84% of the electrical power supplied to the nanotube is dissipated directly into the substrate, rather than in the nanotube itself. Although it has different physical origins, this phenomenon is reminiscent of induction heating or microwave dielectric heating. Such an ability to dissipate waste energy remotely could lead to improved thermal management in electronic devices.

  15. Graphene nanoribbons production from flat carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Melo, W. S.; Guerini, S.; Diniz, E. M., E-mail: eduardo.diniz@ufma.br [Departamento de Física, Universidade Federal do Maranhão, São Luís - MA 65080-805 (Brazil)

    2015-11-14

    Graphene nanoribbons are of great interest for pure and applied sciences due to their unique properties which depend on the nanoribbon edges, as, for example, energy gap and antiferromagnetic coupling. Nevertheless, the synthesis of nanoribbons with well-defined edges remains a challenge. To collaborate with this subject, here we propose a new route for the production of graphene nanoribbons from flat carbon nanotubes filled with a one-dimensional chain of Fe atoms by first principles calculations based on density functional theory. Our results show that Fe-filled flat carbon nanotubes are energetically more stable than non flattened geometries. Also we find that by hydrogenation or oxygenation of the most curved region of the Fe-filled flat armchair carbon nanotube, it occurred a spontaneous production of zigzag graphene nanoribbons which have metallic or semiconducting behavior depending on the edge and size of the graphene nanoribbon. Such findings can be used to create a new method of synthesis of regular-edge carbon nanoribbons.

  16. Carbon nanotube catalysts: recent advances in synthesis, characterization and applications.

    Science.gov (United States)

    Yan, Yibo; Miao, Jianwei; Yang, Zhihong; Xiao, Fang-Xing; Yang, Hong Bin; Liu, Bin; Yang, Yanhui

    2015-05-21

    Carbon nanotubes are promising materials for various applications. In recent years, progress in manufacturing and functionalizing carbon nanotubes has been made to achieve the control of bulk and surface properties including the wettability, acid-base properties, adsorption, electric conductivity and capacitance. In order to gain the optimal benefit of carbon nanotubes, comprehensive understanding on manufacturing and functionalizing carbon nanotubes ought to be systematically developed. This review summarizes methodologies of manufacturing carbon nanotubes via arc discharge, laser ablation and chemical vapor deposition and functionalizing carbon nanotubes through surface oxidation and activation, doping of heteroatoms, halogenation, sulfonation, grafting, polymer coating, noncovalent functionalization and nanoparticle attachment. The characterization techniques detecting the bulk nature and surface properties as well as the effects of various functionalization approaches on modifying the surface properties for specific applications in catalysis including heterogeneous catalysis, photocatalysis, photoelectrocatalysis and electrocatalysis are highlighted.

  17. CARBON NANOTUBES: AN APPROACH TO NOVEL DRUG DELIVERY SYSTEM

    Directory of Open Access Journals (Sweden)

    M. H. Alai et al.

    2012-01-01

    Full Text Available Carbon nanotubes are cylindrical carbon molecules have novel properties, making them potentially useful in many applications in nanotechnology, electronics, optics, and other fields of material science as well as potential uses in architectural fields. They have unique electronic, mechanical, optical and chemical properties that make them good candidates for a wide variety of applications, including drug transporters, new therapeutics, delivery systems and diagnostics. Their unique surface area, stiffness, strength and resilience have led to much excitement in the field of pharmacy. Nanotubes are categorized as single-walled nanotubes, multiple walled nanotubes. Various techniques have been developed to produce nanotubes in sizeable quantities, including arc discharge, laser ablation, chemical vapor deposition. They can pass through membranes, carrying therapeutic drugs, vaccines and nucleic acids deep into the cell to targets previously unreachable. Purification of the tubes can be divided into a couple of main techniques: oxidation, acid treatment, annealing, sonication, filtering and functionalization techniques. The main problem of insolubility in aqueous media has been solved by developing a synthetic protocol that allows highly water-soluble carbon NTs to be obtained. The modifications are done to improve efficiency of carbon nanotubes by formulating luminescent carbon nanotubes, ultrathin carbon nanoneedles, magnetically guided nanotubes. The application of carbon nanotube in tissue engineering, drug carrier release system, wound healing, in cancer treatment and as biosensor. Researchers have recently developed a new approach to Boron Neutron Capture Therapy in the treatment of cancer using substituted Carborane-Appended Water-Soluble single-wall carbon nanotubes.

  18. Adhesion to carbon nanotube conductive scaffolds forces action-potential appearance in immature rat spinal neurons.

    Science.gov (United States)

    Fabbro, Alessandra; Sucapane, Antonietta; Toma, Francesca Maria; Calura, Enrica; Rizzetto, Lisa; Carrieri, Claudia; Roncaglia, Paola; Martinelli, Valentina; Scaini, Denis; Masten, Lara; Turco, Antonio; Gustincich, Stefano; Prato, Maurizio; Ballerini, Laura

    2013-01-01

    In the last decade, carbon nanotube growth substrates have been used to investigate neurons and neuronal networks formation in vitro when guided by artificial nano-scaled cues. Besides, nanotube-based interfaces are being developed, such as prosthesis for monitoring brain activity. We recently described how carbon nanotube substrates alter the electrophysiological and synaptic responses of hippocampal neurons in culture. This observation highlighted the exceptional ability of this material in interfering with nerve tissue growth. Here we test the hypothesis that carbon nanotube scaffolds promote the development of immature neurons isolated from the neonatal rat spinal cord, and maintained in vitro. To address this issue we performed electrophysiological studies associated to gene expression analysis. Our results indicate that spinal neurons plated on electro-conductive carbon nanotubes show a facilitated development. Spinal neurons anticipate the expression of functional markers of maturation, such as the generation of voltage dependent currents or action potentials. These changes are accompanied by a selective modulation of gene expression, involving neuronal and non-neuronal components. Our microarray experiments suggest that carbon nanotube platforms trigger reparative activities involving microglia, in the absence of reactive gliosis. Hence, future tissue scaffolds blended with conductive nanotubes may be exploited to promote cell differentiation and reparative pathways in neural regeneration strategies.

  19. Buckling-driven delamination of carbon nanotube forests

    Science.gov (United States)

    Pour Shahid Saeed Abadi, Parisa; Hutchens, Shelby B.; Greer, Julia R.; Cola, Baratunde A.; Graham, Samuel

    2013-06-01

    We report buckling-driven delamination of carbon nanotube (CNT) forests from their growth substrates when subjected to compression. Macroscale compression experiments reveal local delamination at the CNT forest-substrate interface. Results of microscale flat punch indentations indicate that enhanced CNT interlocking at the top surface of the forest accomplished by application of a metal coating causes delamination of the forest from the growth substrate, a phenomenon not observed in indentation of as-grown CNT forests. We postulate that the post-buckling tensile stresses that develop at the base of the CNT forests serve as the driving force for delamination.

  20. Van der Waals interaction between two crossed carbon nanotubes

    OpenAIRE

    Zhbanov, Alexander I.; Pogorelov, Evgeny G.; Chang, Yia-Chung

    2008-01-01

    The analytical expressions for the van der Waals potential energy and force between two crossed carbon nanotubes are presented. The Lennard-Jones potential for two carbon atoms and the method of the smeared out approximation suggested by L.A. Girifalco were used. The exact formula is expressed in terms of rational and elliptical functions. The potential and force for carbon nanotubes were calculated. The uniform potential curves for single- and multi- wall nanotubes were plotted. The equilibr...