Diameter modulation of vertically aligned single-walled carbon nanotubes.

Science.gov (United States)

Xiang, Rong; Einarsson, Erik; Murakami, Yoichi; Shiomi, Junichiro; Chiashi, Shohei; Tang, Zikang; Maruyama, Shigeo

2012-08-28

We demonstrate wide-range diameter modulation of vertically aligned single-walled carbon nanotubes (SWNTs) using a wet chemistry prepared catalyst. In order to ensure compatibility to electronic applications, the current minimum mean diameter of 2 nm for vertically aligned SWNTs is challenged. The mean diameter is decreased to about 1.4 nm by reducing Co catalyst concentrations to 1/100 or by increasing Mo catalyst concentrations by five times. We also propose a novel spectral analysis method that allows one to distinguish absorbance contributions from the upper, middle, and lower parts of a nanotube array. We use this method to quantitatively characterize the slight diameter change observed along the array height. On the basis of further investigation of the array and catalyst particles, we conclude that catalyst aggregation-rather than Ostwald ripening-dominates the growth of metal particles.

Enhanced ablation of small anodes in a carbon nanotube arc discharge

Science.gov (United States)

Raitses, Yevgeny; Fetterman, Abraham; Keidar, Michael

2008-11-01

An atmospheric pressure helium arc discharge is used for carbon nanotube synthesis. The arc discharge operates in an anodic mode with the ablating anode made from a graphite material. For such conditions, models predict the electron-repelling (negative) anode sheath. In the present experiments, the anode ablation rate is investigated as a function of the anode diameter. It is found that anomalously high ablation occurs for small anode diameters (Fetterman, Y. Raitses and M. Keidar, Carbon (2008).

Diameter sensitive effect in singlewalled carbon nanotubes upon acid treatment

International Nuclear Information System (INIS)

Costa, S.; Borowiak-Palen, E.

2009-01-01

Singlewalled carbon nanotubes (SWCNT) exhibit very unique properties. As an electronic system they undergo amphoteric doping effects (n-type and p-type) which can be reversed. These processes affect the optical and vibronic properties of the carbon nanotubes. The most common and widely used procedure which changes the properties of the SWCNT is acid treatment applied as a purification procedure. This effect has been widely studied but not fully understood so far. Here, we present a study, in which a diameter sensitive effect has been observed. Therefore, two kinds of SWCNT samples have been studied: (i) produced via chemical vapour deposition with a broad diameter distribution, and (ii) synthesised by the laser ablation technique which is commonly known to result in narrow diameter distribution bulk SWCNT samples. Resonance Raman spectroscopy, optical absorption spectroscopy, and Fourier transform middle-infrared spectroscopy have been applied for the characterisation of the samples.

Precise control of multiwall carbon nanotube diameters using thermal chemical vapor deposition

Science.gov (United States)

Siegal, M. P.; Overmyer, D. L.; Provencio, P. P.

2002-03-01

We grow multiwall carbon nanotube (CNT) films using thermal chemical vapor deposition at atmospheric pressure using a mixture of acetylene and nitrogen from a 4-nm-thick Ni film catalyst. CNTs are characterized using electron microscopy and Rutherford backscattering spectrometry. CNTs grown with this method are extremely uniform in diameter, both throughout the sample and within the lengths of individual tubes. Nanotube outer diameters, ranging from 5-350 nm, and the total deposition of carbon material, increase exponentially with growth temperature from 630 °C-790 °C.

The thermal properties of controllable diameter carbon nanotubes synthesized by using AB5 alloy of micrometer magnitude as catalyst

International Nuclear Information System (INIS)

Zhang Haiyan; Chen Yiming; Zeng Guoxun; Huang Huiping; Xie Zhiwei; Jie Xiaohua

2007-01-01

We have synthesized multi-wall carbon nanotubes by catalytic chemical vapour deposition (CCVD) method using an AB 5 hydrogen storage alloy with diameter ranging from 38 to 150 μm as a catalyst. The H 2 uptake capacity of the carbon nanotubes prepared using an AB 5 alloy as a catalyst is about 4 wt.% through to the pressure of 8 MPa at room temperature. Differential thermal analysis-thermogravimetric analysis (DTA-TGA) technique has been applied to investigate the effect of the diameters of the AB 5 alloy catalyst of micrometer magnitude and the technique conditions in the CCVD process on the thermal properties of carbon nanotubes. As the catalyst diameter increases from 38 to 150 μm, the average diameter of the prepared carbon nanotubes increases and the diameter distribution also enlarges. Electron microscope, Raman spectrum and thermal analysis all indicated that the catalyst sizes affect the diameter and the thermal properties of the carbon nanotubes. When the catalyst diameter increases, the initial weight loss temperature and the differential thermal peak temperature of the carbon nanotubes increases, which shows that the lager the diameter of the carbon nanotubes is, the higher the oxidation temperature, and the better the anti-oxidizablity. However, if the diameter of the catalyst is larger than 100 μm, the anti-oxidizablity does not rise anymore but tend to be invariableness. In the CCVD preparation process, the anti-oxidizability of the carbon nanotubes increases, when raising the ratio of the hydrogen gas in the reaction gas in our experimental range (4:1, 3:1, and 2:1, respectively)

Structural transformations of carbon chains inside nanotubes

International Nuclear Information System (INIS)

Warner, Jamie H.; Ruemmeli, Mark H.; Bachmatiuk, Alicja; Buechner, Bernd

2010-01-01

In situ aberration-corrected high-resolution transmission electron microscopy is used to examine the structural transformations of carbon chains that occur in the interior region of carbon nanotubes. We find electron-beam irradiation leads to the formation of two-dimensional carbon structures that are freely mobile inside the nanotube. The inner diameter of the nanotube influences the structural transformations of the carbon chains. As the diameter of the nanotube increases, electron-beam irradiation leads to curling of the chains and eventually the formation of closed looped structures. The closed looped structures evolve into spherical fullerenelike structures that exhibit translational motion inside the nanotubes and also coalesce to form larger nanotube structures. These results demonstrate the use of carbon nanotubes as test tubes for growing small carbon nanotubes within the interior by using only electron-beam irradiation at 80 kV.

Thermal stability of hydrogenated small-diameter carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Podlivaev, A. I., E-mail: AIPodlivayev@mephi.ru; Openov, L. A. [National Research Nuclear University “MEPhI” (Russian Federation)

2017-02-15

The initial stage of hydrogen desorption from fully hydrogenated carbon nanotubes (3.0) and (2.2) is numerically studied by the molecular dynamics method. The temperature dependence of the desorption rate is directly determined at T = 1800–2500 K. The characteristic desorption times are determined at temperatures outside this range by extrapolation. It is shown that hydrogen desorption leads to the appearance of electronic states in the band gap.

Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts

Science.gov (United States)

Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

2016-01-01

We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices.We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high

Nonlinear buckling analyses of a small-radius carbon nanotube

International Nuclear Information System (INIS)

Liu, Ning; Li, Min; Jia, Jiao; Wang, Yong-Gang

2014-01-01

Carbon nanotube (CNT) was first discovered by Sumio Iijima. It has aroused extensive attentions of scholars from all over the world. Over the past two decades, we have acquired a lot of methods to synthesize carbon nanotubes and learn their many incredible mechanical properties such as experimental methods, theoretical analyses, and computer simulations. However, the studies of experiments need lots of financial, material, and labor resources. The calculations will become difficult and time-consuming, and the calculations may be even beyond the realm of possibility when the scale of simulations is large, as for computer simulations. Therefore, it is necessary for us to explore a reasonable continuum model, which can be applied into nano-scale. This paper attempts to develop a mathematical model of a small-radius carbon nanotube based on continuum theory. An Isotropic circular cross-section, Timoshenko beam model is used as a simplified mechanical model for the small-radius carbon nanotube. Theoretical part is mainly based on modified couple stress theory to obtain the numerical solutions of buckling deformation. Meanwhile, the buckling behavior of the small radius carbon nanotube is simulated by Molecular Dynamics method. By comparing with the numerical results based on modified couple stress theory, the dependence of the small-radius carbon nanotube mechanical behaviors on its elasticity constants, small-size effect, geometric nonlinearity, and shear effect is further studied, and an estimation of the small-scale parameter of a CNT (5, 5) is obtained

Nonlinear buckling analyses of a small-radius carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Liu, Ning, E-mail: liuxiao@ase.buaa.edu.cn; Li, Min; Jia, Jiao [School of Aeronautic Science and Engineering, Beihang University, Beijing 100091 (China); Wang, Yong-Gang [Department of Applied Mechanics, China Agricultural University, Beijing 100083 (China)

2014-04-21

Carbon nanotube (CNT) was first discovered by Sumio Iijima. It has aroused extensive attentions of scholars from all over the world. Over the past two decades, we have acquired a lot of methods to synthesize carbon nanotubes and learn their many incredible mechanical properties such as experimental methods, theoretical analyses, and computer simulations. However, the studies of experiments need lots of financial, material, and labor resources. The calculations will become difficult and time-consuming, and the calculations may be even beyond the realm of possibility when the scale of simulations is large, as for computer simulations. Therefore, it is necessary for us to explore a reasonable continuum model, which can be applied into nano-scale. This paper attempts to develop a mathematical model of a small-radius carbon nanotube based on continuum theory. An Isotropic circular cross-section, Timoshenko beam model is used as a simplified mechanical model for the small-radius carbon nanotube. Theoretical part is mainly based on modified couple stress theory to obtain the numerical solutions of buckling deformation. Meanwhile, the buckling behavior of the small radius carbon nanotube is simulated by Molecular Dynamics method. By comparing with the numerical results based on modified couple stress theory, the dependence of the small-radius carbon nanotube mechanical behaviors on its elasticity constants, small-size effect, geometric nonlinearity, and shear effect is further studied, and an estimation of the small-scale parameter of a CNT (5, 5) is obtained.

Diameter-dependent release of a cisplatin pro-drug from small and large functionalized carbon nanotubes

Science.gov (United States)

Muzi, Laura; Ménard-Moyon, Cécilia; Russier, Julie; Li, Jian; Chin, Chee Fei; Ang, Wee Han; Pastorin, Giorgia; Risuleo, Gianfranco; Bianco, Alberto

2015-03-01

The use of platinum-based chemotherapeutic drugs in cancer therapy still suffers from severe disadvantages, such as lack of appropriate selectivity for tumor tissues and insurgence of multi-drug resistance. Moreover, drug efficacy can be attenuated by several mechanisms such as premature drug inactivation, reduced drug uptake inside cells and increased drug efflux once internalized. The use of functionalized carbon nanotubes (CNTs) as chemotherapeutic drug delivery systems is a promising strategy to overcome such limitations due to their ability to enhance cellular internalization of poorly permeable drugs and thus increase the drug bioavailability at the diseased site, compared to the free drug. Furthermore, the possibility to encapsulate agents in the nanotubes' inner cavity can protect the drug from early inactivation and their external functionalizable surface is useful for selective targeting. In this study, a hydrophobic platinum(iv) complex was encapsulated within the inner space of two different diameter functionalized multi-walled CNTs (Pt(iv)@CNTs). The behavior of the complexes, compared to the free drug, was investigated on both HeLa human cancer cells and RAW 264.7 murine macrophages. Both CNT samples efficiently induced cell death in HeLa cancer cells 72 hours after the end of exposure to CNTs. Although the larger diameter CNTs were more cytotoxic on HeLa cells compared to both the free drug and the smaller diameter nanotubes, the latter allowed a prolonged release of the encapsulated drug, thus increasing its anticancer efficacy. In contrast, both Pt(iv)@CNT constructs were poorly cytotoxic on macrophages and induced negligible cell activation and no pro-inflammatory cytokine production. Both CNT samples were efficiently internalized by the two types of cells, as demonstrated by transmission electron microscopy observations and flow cytometry analysis. Finally, the platinum levels found in the cells after Pt(iv)@CNT exposure demonstrate that they can

Conducting carbonized polyaniline nanotubes

International Nuclear Information System (INIS)

Mentus, Slavko; Ciric-Marjanovic, Gordana; Trchova, Miroslava; Stejskal, Jaroslav

2009-01-01

Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min -1 up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 μm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 μm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm -1 , increased to 0.7 S cm -1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

Conducting carbonized polyaniline nanotubes

Energy Technology Data Exchange (ETDEWEB)

Mentus, Slavko; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.rs

2009-06-17

Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min{sup -1} up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 {mu}m, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 {mu}m, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm{sup -1}, increased to 0.7 S cm{sup -1} upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

Diameter grouping in bulk samples of single-walled carbon nanotubes from optical absorption spectroscopy

NARCIS (Netherlands)

Golden, M.S.; Fink, J.; Dunsch, L.; Bauer, H.-D.; Reibold, M.; Knupfer, M.; Friedlein, R.; Pichler, T.; Jost, O.

1999-01-01

The influence of the synthesis parameters on the mean characteristics of single-wall carbon nanotubes in soot produced by the laser vaporization of graphite has been analyzed using optical absorption spectroscopy. The abundance and mean diameter of the nanotubes were found to be most influenced by

Electrostrictive deformations in small carbon clusters, hydrocarbon molecules, and carbon nanotubes

International Nuclear Information System (INIS)

Cabria, I.; Lopez, M. J.; Alonso, J. A.; Amovilli, C.; March, N. H.

2006-01-01

The electrostrictive response of small carbon clusters, hydrocarbon molecules, and carbon nanotubes is investigated using the density functional theory. For ringlike carbon clusters, one can get insight on the deformations induced by an electric field from a simple two-dimensional model in which the positive charge of the carbon ions is smeared out in a circular homogeneous line of charge and the electronic density is calculated for a constant applied electric field within a two-dimensional Thomas-Fermi method. According to the Hellmann-Feynman theorem, this model predicts, for fields of about 1 V/A ring , only a small elongation of the ring clusters in the direction of the electric field. Full three-dimensional density functional calculations with an external electric field show similar small deformations in the ring carbon clusters compared to the simple model. The saturated benzene and phenanthrene hydrocarbon molecules do not experience any deformation, even under the action of relatively intense (1 V/A ring ) electric fields. In contrast, finite carbon nanotubes experience larger elongations (∼2.9%) induced by relatively weak (0.1 V/A ring ) applied electric fields. Both C-C bond length elongation and the deformation of the honeycomb structure contribute equally to the nanotube elongation. The effect of the electric field in hydrogen terminated nanotubes is reduced with respect to the nanotubes with dangling bonds in the edges

Electroless reductions on carbon nanotubes: How critical is the diameter of a nanotube

KAUST Repository

Guo, Yong

2013-01-01

Detailed experimental and theoretical studies have been performed to investigate the influence of the diameter of multi-walled carboxy-functionalized carbon nanotubes (CFCNTs) on their ability to reduce PdCl4 2- salt to Pd nanoparticles on their surface at room temperature. The obtained results (inductively-coupled plasmaspectrometry and cyclic voltammetry) show that the reduction ability of CFCNTs with 5 nm diameter (CFCNT5) is stronger than that of CFCNTs with 15 nm diameter (CFCNT15). Density Functional Theory (DFT) calculations suggest that a more negative charge distribution exists on CFCNT5, which makes it a better electron donor to PdCl42-. This journal is © The Royal Society of Chemistry.

Anode Sheath Switching in a Carbon Nanotube Arc Plasma

International Nuclear Information System (INIS)

Fetterman, Abe; Raitses, Yevgeny; Keidar, Michael

2008-01-01

The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

Diameter Tuning of Single-Walled Carbon Nanotubes by Diffusion Plasma CVD

Directory of Open Access Journals (Sweden)

Toshiaki Kato

2011-01-01

Full Text Available We have realized a diameter tuning of single-walled carbon nanotubes (SWNTs by adjusting process gas pressures with plasma chemical vapor deposition (CVD. Detailed photoluminescence measurements reveal that the diameter distribution of SWNTs clearly shifts to a large-diameter region with an increase in the pressure during plasma CVD, which is also confirmed by Raman scattering spectroscopy. Based on the systematical investigation, it is found that the main diameter of SWNTs is determined by the pressure during the heating in an atmosphere of hydrogen and the diameter distribution is narrowed by adjusting the pressure during the plasma generation. Our results could contribute to an application of SWNTs to high-performance thin-film transistors, which requires the diameter-controlled semiconductor-rich SWNTs.

Spectroscopic study of the diameter distribution of B-doped single-walled carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Ruiz-Soria, G.; Pichler, T.; Ayala, P. [University of Vienna, Faculty of Physics, 1090 Vienna (Austria); Daothong, S. [Chiang Mai University, Faculty of Science, 50200 Chiang Mai (Thailand)

2012-12-15

In this paper, we report on the diameter distribution of boron-doped single-walled carbon nanotubes grown from triethyl borate with high vacuum chemical vapor deposition, using multi-frequency Raman resonance spectroscopy. The nanotube yield is higher than in previously reported material produced with the same method. Our results suggest that the amount of as-grown material and the range of diameters are directly correlated with feedstock used in the synthesis. The I{sub D}/I{sub G} ratio shows that the morphology of the samples is critically affected by the temperature. The population of diameters in the optimal conditions shows a Poisson distribution with a mean value at {proportional_to}1.15 nm. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Exploring the diameter and surface dependent conformational changes in carbon nanotube-protein corona and the related cytotoxicity

International Nuclear Information System (INIS)

Zhao, Xingchen; Lu, Dawei; Hao, Fang; Liu, Rutao

2015-01-01

Highlights: • CNT diameter and surface area govern the stability of adsorbed proteins. • More BSA was loaded and destabilized on smaller CNTs. • Protein corona reduces the cytotoxicity of CNTs - Abstract: In this work, we investigated and compared carbon nanotubes (CNTs) of different diameters regarding their interaction with bovine serum albumin (BSA) and their ability to alter protein structure. BSA was exposed to CNT solutions, and the effects were assessed by utilizing fluorescence spectroscopy, UV–vis absorption spectroscopy, circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM), bichinchoninic acid (BCA) and zeta-potential measurement assays. We demonstrate that CNT diameter and surface area play key roles in influencing the stability of adsorbed proteins. Results showed that the secondary and tertiary structural stability of BSA decreased upon adsorption onto CNTs, with greater decrease on smaller-diametered nanotubes. Besides, more protein was loaded onto CNTs with small diameter, reducing the cytotoxicity. This study, therefore, provides fundamental information for the influence of CNT diameter and surface on protein behavior, which may be helpful to understand toxic effects of CNTs and prove beneficial for developing novel biomedical devices and safe use of nanomaterials

Conformational analysis and electronic structure of chiral carbon and carbon nitride nanotubes

Directory of Open Access Journals (Sweden)

Cristiano Geraldo de Faria

2011-12-01

Full Text Available Geometry and electronic structure of chiral carbon and carbon nitride (CNx nanotubes were investigated through quantum chemical methods. Finite nanotubes with diameters ranging from 5 to 10 Å and containing up to 500 atoms were considered. CNx structures were built through random substitution of carbon atoms by nitrogen. The molecules were fully optimized by semi-empirical quantum chemical method (PM3. Our results show that the energy associated with nitrogen incorporation depends strongly upon the tube helicity and diameter. The doping of nanotubes with nitrogen contributes to reduce the stress caused by the small diameter of the studied systems. Density of States (DOS results for pure carbon and CNx nanostructures, obtained through DFT and Hartree-Fock calculations, were analyzed. The introduction of nitrogen in the tube produce states in the gap region which characterizes the metallic behavior, as expected for these systems after N-doping.

Diameter-dependent hydrophobicity in carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Kyakuno, Haruka, E-mail: h-kyakuno@kanagawa-u.ac.jp [Department of Physics, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Institute of Physics, Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan); Fukasawa, Mamoru; Ichimura, Ryota; Nakai, Yusuke; Maniwa, Yutaka, E-mail: maniwa@phys.se.tmu.ac.jp [Department of Physics, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Matsuda, Kazuyuki [Institute of Physics, Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan); Miyata, Yasumitsu [Department of Physics, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); PRESTO, JST, Kawaguchi 332-0012 (Japan); Saito, Takeshi [Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565 (Japan)

2016-08-14

Single-wall carbon nanotubes (SWCNTs) are a good model system that provides atomically smooth nanocavities. It has been reported that water-SWCNTs exhibit hydrophobicity depending on the temperature T and the SWCNT diameter D. SWCNTs adsorb water molecules spontaneously in their cylindrical pores around room temperature, whereas they exhibit a hydrophilic-hydrophobic transition or wet-dry transition (WDT) at a critical temperature T{sub wd} ≈ 220-230 K and above a critical diameter D{sub c} ≈ 1.4-1.6 nm. However, details of the WDT phenomenon and its mechanism remain unknown. Here, we report a systematic experimental study involving X-ray diffraction, optical microscopy, and differential scanning calorimetry. It is found that water molecules inside thick SWCNTs (D > D{sub c}) evaporate and condense into ice Ih outside the SWCNTs at T{sub wd} upon cooling, and the ice Ih evaporates and condenses inside the SWCNTs upon heating. On the other hand, residual water trapped inside the SWCNTs below T{sub wd} freezes. Molecular dynamics simulations indicate that upon lowering T, the hydrophobicity of thick SWCNTs increases without any structural transition, while the water inside thin SWCNTs (D < D{sub c}) exhibits a structural transition, forming an ordered ice. This ice has a well-developed hydrogen bonding network adapting to the cylindrical pores of the SWCNTs. Thus, the unusual diameter dependence of the WDT is attributed to the adaptability of the structure of water to the pore dimension and shape.

Electrical conductance of carbon nanotubes with misaligned ends

Energy Technology Data Exchange (ETDEWEB)

Pantano, Antonio, E-mail: antonio.pantano@unipa.it; Muratore, Giuseppe; Montinaro, Nicola [Universita degli Studi di Palermo, Dipartimento di Ingegneria Chimica, Gestionale, Informatica e Meccanica (Italy)

2013-09-15

During a manufacturing process, when a straight carbon nanotube is placed on a substrate, e.g., production of transistors, its two ends are often misaligned. In this study, we investigate the effects of multiwall carbon nanotubes' (MWCNTs) outer diameter and chirality on the change in conductance due to misalignment of the two ends. The length of the studied MWCNTs was 120 nm, while the diameters ranged between 4 and 7 nm. A mixed finite element-tight-binding approach was carefully designed to realize reduction in computational time by orders of magnitude in calculating the deformation-induced changes in the electrical transport properties of the nanotubes. Numerical results suggest that armchair MWCNTs of small diameter should work better if used as conductors, while zigzag MWCNTs of large diameter are more suitable for building sensors.Graphical Abstract.

Carbon nanotubes and methods of making carbon nanotubes

KAUST Repository

Basset, Jean-Marie; Zhou, Lu; Saih, Youssef

2017-01-01

Embodiments of the present disclosure provide for methods that can be used to produce carbon nanotubes (hereinafter CNT) having an inner diameter about 5-55 nm, methods of tuning the inner diameter of CNTs (e.g., by adjusting reaction pressure

Carbon nanotubes and methods of making carbon nanotubes

KAUST Repository

Basset, Jean-Marie

2017-04-27

Embodiments of the present disclosure provide for methods that can be used to produce carbon nanotubes (hereinafter CNT) having an inner diameter about 5-55 nm, methods of tuning the inner diameter of CNTs (e.g., by adjusting reaction pressure), CNTs having an inner diameter of greater than 20 nm or more, and the like.

Oxidation behavior of multiwall carbon nanotubes with different diameters and morphology

Energy Technology Data Exchange (ETDEWEB)

Mazov, Ilya, E-mail: ilya.mazov@gmail.com [Boreskov Institute of Catalysis, Lavrentieva ave. 5, Novosibirsk, 630090 (Russian Federation); Kuznetsov, Vladimir L. [Boreskov Institute of Catalysis, Lavrentieva ave. 5, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova st. 2, Novosibirsk, 630090 (Russian Federation); Simonova, Irina A. [Boreskov Institute of Catalysis, Lavrentieva ave. 5, Novosibirsk, 630090 (Russian Federation); Stadnichenko, Andrey I. [Boreskov Institute of Catalysis, Lavrentieva ave. 5, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova st. 2, Novosibirsk, 630090 (Russian Federation); Ishchenko, Arkady V. [Boreskov Institute of Catalysis, Lavrentieva ave. 5, Novosibirsk, 630090 (Russian Federation); Romanenko, Anatoly I.; Tkachev, Evgeniy N.; Anikeeva, Olga B. [Nikolaev Institute of Inorganic Chemistry, Lavrentieva ave. 3, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Pirogova st. 2, Novosibirsk, 630090 (Russian Federation)

2012-06-15

Multiwall carbon nanotubes (MWNT) with three medium diameters (20-22, 9-13, and 6-8 nm) and different morphology were chemically oxidized using concentrated nitric acid, mixture of nitric and sulfuric acids ('melange' solution) and mixture of sulfuric acid and hydrogen peroxide ('piranha' solution). Influence of MWNT type and structure as well as type of oxidizer on the surface composition and structure of nanotubes after oxidation was investigated. Acid-base titration, X-ray photoelectron spectroscopy and thermal gravimetric analysis were used for quantitative and qualitative investigation of surface group composition of initial and oxidized nanotubes. Amount of oxygen-containing groups on the surface of oxidized MWNT depends on the type of initial MWNT. It was found that ratio of different oxygen containing groups is less dependent on the type of oxidizer. Electrophysical properties of initial and oxidized nanotubes were investigated in temperature range 4-293 K and main types of electrical conductivity were determined. It was shown that oxidation results in decrease in electrical conductivity of all samples with simultaneous change in the conductivity mechanism. Dispersive behavior of initial and oxidized nanotubes in different commonly used solvents was investigated. It was shown that oxidation leads to the improvement of sedimentation stability of MWNT in polar solvents.

Oxidation behavior of multiwall carbon nanotubes with different diameters and morphology

Science.gov (United States)

Mazov, Ilya; Kuznetsov, Vladimir L.; Simonova, Irina A.; Stadnichenko, Andrey I.; Ishchenko, Arkady V.; Romanenko, Anatoly I.; Tkachev, Evgeniy N.; Anikeeva, Olga B.

2012-06-01

Multiwall carbon nanotubes (MWNT) with three medium diameters (20-22, 9-13, and 6-8 nm) and different morphology were chemically oxidized using concentrated nitric acid, mixture of nitric and sulfuric acids ("mélange" solution) and mixture of sulfuric acid and hydrogen peroxide ("piranha" solution). Influence of MWNT type and structure as well as type of oxidizer on the surface composition and structure of nanotubes after oxidation was investigated. Acid-base titration, X-ray photoelectron spectroscopy and thermal gravimetric analysis were used for quantitative and qualitative investigation of surface group composition of initial and oxidized nanotubes. Amount of oxygen-containing groups on the surface of oxidized MWNT depends on the type of initial MWNT. It was found that ratio of different oxygen containing groups is less dependent on the type of oxidizer. Electrophysical properties of initial and oxidized nanotubes were investigated in temperature range 4-293 K and main types of electrical conductivity were determined. It was shown that oxidation results in decrease in electrical conductivity of all samples with simultaneous change in the conductivity mechanism. Dispersive behavior of initial and oxidized nanotubes in different commonly used solvents was investigated. It was shown that oxidation leads to the improvement of sedimentation stability of MWNT in polar solvents.

Unzipping of multi-wall carbon nanotubes with different diameter distributions: Effect on few-layer graphene oxide obtention

Science.gov (United States)

Torres, D.; Pinilla, J. L.; Suelves, I.

2017-12-01

Few-layer graphene oxide (FLGO) was obtained by chemical unzipping of multi-wall carbon nanotubes (MWCNT) of different diameter distributions. MWCNT were synthesized by catalytic decomposition of methane using Fe-Mo/MgO catalysts. The variation in the Fe/Mo ratio (1, 2 and 5) was very influential in MWCNT diameter distribution and type of MWCNT obtained, including textural, chemical, structural and morphological characteristics. MWCNT diameter distribution and surface defects content had a profound impact on the characteristics of the resulting FLGO. Thus, MWCNT obtained with the catalyst with a Fe/Mo: 5 and presenting a narrow diameter distribution centered at 8.6 ± 3.3 nm led to FLGO maintaining non-oxidized graphite stacking (according to XRD analysis), lower specific surface area and higher thermostability as compared to FLGO obtained from MWCNT showing wider diameter distributions. The presence of more oxygen-containing functionalities and structural defects in large diameter nanotubes promotes the intercalation of species towards the inner layers of the nanotube, resulting in an enhanced MWCNT oxidation and opening into FLGO, what improves both micro- and mesoporosity.

Process for derivatizing carbon nanotubes with diazonium species

Science.gov (United States)

Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

2007-01-01

The invention incorporates new processes for the chemical modification of carbon nanotubes. Such processes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications and sensor devices. The methods of derivatization include electrochemical induced reactions thermally induced reactions (via in-situ generation of diazonium compounds or pre-formed diazonium compounds), and photochemically induced reactions. The derivatization causes significant changes in the spectroscopic properties of the nanotubes. The estimated degree of functionality is ca. 1 out of every 20 to 30 carbons in a nanotube bearing a functionality moiety. Such electrochemical reduction processes can be adapted to apply site-selective chemical functionalization of nanotubes. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes ##STR00001##.

Diameter control and emission properties of carbon nanotubes grown using chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Kaatz, F.H.; Siegal, M.P.; Overmyer, D.L.; Provencio, P.P.; Jackson, J.L

2003-01-15

We grow multiwalled carbon nanotubes (CNTs) via thermal chemical vapor deposition from a sputtered 4-nm-thick nickel catalyst film on a tungsten-coated silicon substrate. CNTs grow from a mixture of nitrogen and acetylene gases at temperatures ranging from 630 to 790 deg. C, resulting in CNT outer diameters of 5-350 nm. CNT diameters increase exponentially with temperature. These results define regimes for template growth fabricated in catalytically active anodized aluminum oxide (AAO) with controlled pinhole sizes ranging from 10 to 50 nm. We measure a threshold electron emission field of 3 V/{mu}m and a field enhancement factor {beta}=5230 on randomly oriented 10-nm diameter CNTs.

Diameter control and emission properties of carbon nanotubes grown using chemical vapor deposition

International Nuclear Information System (INIS)

Kaatz, F.H.; Siegal, M.P.; Overmyer, D.L.; Provencio, P.P.; Jackson, J.L.

2003-01-01

We grow multiwalled carbon nanotubes (CNTs) via thermal chemical vapor deposition from a sputtered 4-nm-thick nickel catalyst film on a tungsten-coated silicon substrate. CNTs grow from a mixture of nitrogen and acetylene gases at temperatures ranging from 630 to 790 deg. C, resulting in CNT outer diameters of 5-350 nm. CNT diameters increase exponentially with temperature. These results define regimes for template growth fabricated in catalytically active anodized aluminum oxide (AAO) with controlled pinhole sizes ranging from 10 to 50 nm. We measure a threshold electron emission field of 3 V/μm and a field enhancement factor β=5230 on randomly oriented 10-nm diameter CNTs

Diameter-Sensitive Breakdown of Single-Walled Carbon Nanotubes upon KOH Activation.

Science.gov (United States)

Ye, Jianglin; Wu, Shuilin; Ni, Kun; Tan, Ziqi; Xu, Jin; Tao, Zhuchen; Zhu, Yanwu

2017-07-19

While potassium hydroxide (KOH) activation has been used to create pores in carbon nanotubes (CNTs) for improved energy-storage performance, the KOH activation mechanism of CNTs has been rarely investigated. In this work, the reaction between single-walled CNTs (SWCNTs) and KOH is studied in situ by thermogravimetric analysis coupled to infrared (IR) spectroscopy and gas chromatography/mass spectrometry (MS). The IR and MS results clearly demonstrate the sequential evolution of CO, hydrocarbons, CO 2 , and H 2 O in the activation process. By using the radial breathing mode of Raman spectroscopy, a diameter-sensitive selectivity is observed in the reaction between SWCNTs and KOH, leading to a preferential distribution of SWCNTs with diameters larger than 1 nm after activation at 900 °C and a preferential removal of SWCNTs with diameters below 1 nm upon activation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Process for derivatizing carbon nanotubes with diazonium species and compositions thereof

Science.gov (United States)

Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

2011-01-01

Methods for the chemical modification of carbon nanotubes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications, and sensor devices. The methods of derivatization include electrochemical induced reactions, thermally induced reactions, and photochemically induced reactions. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes.

Effect of Hydrogen Adsorption on the Stone-Wales Transformation in Small-Diameter Carbon Nanotubes

Science.gov (United States)

Openov, L. A.; Podlivaev, A. I.

2018-04-01

The effect of hydrogenation of (4, 0) and (3, 0) carbon nanotubes on the Stone-Wales transformation is studied in the framework of the nonorthogonal tight-binding model. It is shown that the atomic hydrogen adsorption can lead to both a decrease and an increase in the barriers for the direct and inverse transformations depending on the orientation of a rotating C-C bond with respect to the nanotube axis. The characteristic times of formation and annealing the Stone-Wales defects have been estimated. The Young's moduli have been calculated.

Synthesis of Carbon Nanotubes of Few Walls Using Aliphatic Alcohols as a Carbon Source

Directory of Open Access Journals (Sweden)

Francisco Espinosa-Magaña

2013-06-01

Full Text Available Carbon nanotubes with single and few walls are highly appreciated for their technological applications, regardless of the limited availability due to their high production cost. In this paper we present an alternative process that can lead to lowering the manufacturing cost of CNTs of only few walls by means of the use of the spray pyrolysis technique. For this purpose, ferrocene is utilized as a catalyst and aliphatic alcohols (methanol, ethanol, propanol or butanol as the carbon source. The characterization of CNTs was performed by scanning electron microscopy (SEM and transmission electron microscopy (TEM. The study of the synthesized carbon nanotubes (CNTs show important differences in the number of layers that constitute the nanotubes, the diameter length, the quantity and the quality as a function of the number of carbons employed in the alcohol. The main interest of this study is to give the basis of an efficient synthesis process to produce CNTs of few walls for applications where small diameter is required.

Novel strategy for diameter-selective separation and functionalization of single-wall carbon nanotubes.

Science.gov (United States)

Tromp, R M; Afzali, A; Freitag, M; Mitzi, D B; Chen, Zh

2008-02-01

The problem of separating single-wall carbon nanotubes (CNTs) by diameter and/or chirality is one of the greatest impediments toward the widespread application of these promising materials in nanoelectronics. In this paper, we describe a novel physical-chemical method for diameter-selective CNT separation that is both simple and effective and that allows up-scaling to large volumes at modest cost. Separation is based on size-selective noncovalent matching of an appropriate anchor molecule to the wall of the CNT, enabling suspension of the CNTs in solvents in which they would otherwise not be soluble. We demonstrate size-selective separation in the 1-2 nm diameter range using easily synthesized oligo-acene adducts as a diameter-selective molecular anchor. CNT field effect transistors fabricated from diameter-selected CNTs show markedly improved electrical properties as compared to nonselected CNTs.

Investigation of the interfacial properties of polyurethane/carbon nanotube hybrid composites: A molecular dynamics study

Science.gov (United States)

Goclon, Jakub; Panczyk, Tomasz; Winkler, Krzysztof

2018-03-01

Considering the varied applications of hybrid polymer/carbon nanotube composites and the constant progress in the synthesis methods of such materials, we report a theoretical study of interfacial layer formation between pristine single-wall carbon nanotubes (SWCNTs) and polyurethane (PU) using molecular dynamic simulations. We vary the SWCNT diameter and the number of PU chains to examine various PU-SWCNT interaction patterns. Our simulations indicate the important role of intra-chain forces in PU. No regular polymeric structures could be identified on the carbon nanotube surface during the simulations. We find that increasing the SWCNT diameter results in stronger polymer binding. However, higher surface loadings of PU lead to stronger interpenetration by the polymeric segments; this effect is more apparent for SWCNTs with small diameters. Our core finding is that the attached PU binds most strongly to the carbon nanotubes with the largest diameters. Polymer dynamics reveal the loose distribution of PU chains in these systems.

Carbon nanotube composite materials

Science.gov (United States)

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.

Length-scale and strain rate-dependent mechanism of defect formation and fracture in carbon nanotubes under tensile loading

Energy Technology Data Exchange (ETDEWEB)

Javvaji, Brahmanandam [Indian Institute of Science, Department of Aerospace Engineering (India); Raha, S. [Indian Institute of Science, Department of Computational and Data Sciences (India); Mahapatra, D. Roy, E-mail: droymahapatra@aero.iisc.ernet.in [Indian Institute of Science, Department of Aerospace Engineering (India)

2017-02-15

Electromagnetic and thermo-mechanical forces play a major role in nanotube-based materials and devices. Under high-energy electron transport or high current densities, carbon nanotubes fail via sequential fracture. The failure sequence is governed by certain length scale and flow of current. We report a unified phenomenological model derived from molecular dynamic simulation data, which successfully captures the important physics of the complex failure process. Length-scale and strain rate-dependent defect nucleation, growth, and fracture in single-walled carbon nanotubes with diameters in the range of 0.47 to 2.03 nm and length which is about 6.17 to 26.45 nm are simulated. Nanotubes with long length and small diameter show brittle fracture, while those with short length and large diameter show transition from ductile to brittle fracture. In short nanotubes with small diameters, we observe several structural transitions like Stone-Wales defect initiation, its propagation to larger void nucleation, formation of multiple chains of atoms, conversion to monatomic chain of atoms, and finally complete fracture of the carbon nanotube. Hybridization state of carbon-carbon bonds near the end cap evolves, leading to the formation of monatomic chain in short nanotubes with small diameter. Transition from ductile to brittle fracture is also observed when strain rate exceeds a critical value. A generalized analytical model of failure is established, which correlates the defect energy during the formation of atomic chain with aspect ratio of the nanotube and strain rate. Variation in the mechanical properties such as elastic modulus, tensile strength, and fracture strain with the size and strain rate shows important implications in mitigating force fields and ways to enhance the life of electronic devices and nanomaterial conversion via fracture in manufacturing.

Reconstruction of mono-vacancies in carbon nanotubes: Atomic relaxation vs. spin polarization

Energy Technology Data Exchange (ETDEWEB)

Berber, S. [Institute of Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571 (Japan)]. E-mail: berber@comas.frsc.tsukuba.ac.jp; Oshiyama, A. [Institute of Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571 (Japan)

2006-04-01

We have investigated the reconstruction of mono-vacancies in carbon nanotubes using density functional theory (DFT) geometry optimization and electronic structure calculations, employing a numerical basis set. We considered mono-vacancies in achiral nanotubes with diameter range {approx}4-9A. Contrary to previous tight-binding calculations, our results indicate that mono-vacancies could have several metastable geometries, confirming the previous plane-wave DFT results. Formation energy of mono-vacancies is 4.5-5.5eV, increasing with increasing tube diameter. Net magnetic moment decreases from ideal mono-vacancy value after reconstruction, reflecting the reduction of the number of dangling bonds. In spite of the existence of a dangling bond, ground state of mono-vacancies in semiconducting tubes have no spin polarization. Metallic carbon nanotubes show net magnetic moment for most stable structure of mono-vacancy, except for very small diameter tubes.

Reconstruction of mono-vacancies in carbon nanotubes: Atomic relaxation vs. spin polarization

International Nuclear Information System (INIS)

Berber, S.; Oshiyama, A.

2006-01-01

We have investigated the reconstruction of mono-vacancies in carbon nanotubes using density functional theory (DFT) geometry optimization and electronic structure calculations, employing a numerical basis set. We considered mono-vacancies in achiral nanotubes with diameter range ∼4-9A. Contrary to previous tight-binding calculations, our results indicate that mono-vacancies could have several metastable geometries, confirming the previous plane-wave DFT results. Formation energy of mono-vacancies is 4.5-5.5eV, increasing with increasing tube diameter. Net magnetic moment decreases from ideal mono-vacancy value after reconstruction, reflecting the reduction of the number of dangling bonds. In spite of the existence of a dangling bond, ground state of mono-vacancies in semiconducting tubes have no spin polarization. Metallic carbon nanotubes show net magnetic moment for most stable structure of mono-vacancy, except for very small diameter tubes

Black silicon maskless templates for carbon nanotube forests

DEFF Research Database (Denmark)

Wierzbicki, Rafal; Schmidt, Michael Stenbæk; Boisen, Anja

2013-01-01

allows maskless definition of carbon nanotube forests with control of their density, nanotube diameter and height. Four nanograss reactive ion etching recipes are investigated and their wafer-to-wafer repeatability, wafer uniformity, and density control is discussed. Evaluation of carbon nanotube forests...

Lithium storage properties of multiwall carbon nanotubes prepared by CVD

International Nuclear Information System (INIS)

Ahn, J.-O.; Andong National University,; Wang, G.X.; Liu, H.K.; Dou, S.X.

2003-01-01

Full text: Multiwall carbon nanotubes (MWCNTs) were synthesised by chemical vapour deposition (CVD) method using acetylene gas. The XRD pattern of as prepared carbon nanotubes showed that the d 002 value is 3.44 Angstroms. The morphology and microstructure of carbon nanotubes were characterized by HRTEM. Most of carbon nanotubes are entangled together to form bundles or ropes. The diameter of the carbon nanotubes is in the range of 10 ∼ 20 nm. There is a small amount of amorphous carbon particles presented in the sample. However, the yield of carbon nanotubes is more than 95%. Electrochemical properties of carbon nanotubes were characterised via a variety of electrochemical testing techniques. The result of CV test showed that the Li insertion potential is quite low, which is very close to O V versus Li + /Li reference electrode, whereas the potential for Li de-intercalation is in the range of 0.2-0.4 V. There exists a slight voltage hysteresis between Li intercalation and Li de-intercalation, which is similar to the other carbonaceous materials. The intensity of redox peaks of carbon nanotubes decrease with scanning cycle, indicating that the reversible Li insertion capacity gradually decreases. The carbon nanotubes electrode demonstrated a reversible lithium storage capacity of 340 mAh/g with good cyclability at moderate current density. Further improvement of Li storage capacity is possible by opening the end of carbon nanotubes to allow lithium insertion into inner graphene sheet of carbon nanotubes. The kinetic properties of lithium insertion in carbon nanotube electrodes were characterised by a.c. impedance measurements. It was found that the lithium diffusion coefficient d Li decreases with an increase of Li ion concentration in carbon nanotube host

Synthesis of PbI(2) single-layered inorganic nanotubes encapsulated within carbon nanotubes.

Science.gov (United States)

Cabana, Laura; Ballesteros, Belén; Batista, Eudar; Magén, César; Arenal, Raúl; Oró-Solé, Judith; Rurali, Riccardo; Tobias, Gerard

2014-04-02

The template assisted growth of single-layered inorganic nanotubes is reported. Single-crystalline lead iodide single-layered nanotubes have been prepared using the inner cavities of carbon nanotubes as hosting templates. The diameter of the resulting inorganic nanotubes is merely dependent on the diameter of the host. This facile method is highly versatile opening up new horizons in the preparation of single-layered nanostructures. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tuning the electronic properties by width and length modifications of narrow-diameter carbon nanotubes for nanomedicine

KAUST Repository

Poater, Albert; Saliner, Ana Gallegos; Cavallo, Luigi; Poch, Manel P.; Solà , Miquel; Worth, Andrew P.

2012-01-01

The distinctive characteristics of nanoparticles, resulting from properties that arise at the nano-scale, underlie their potential applications in the biomedical sector. However, the very same characteristics also result in widespread concerns about the potentially toxic effects of nanoparticles. Given the large number of nanoparticles that are being developed for possible biomedical use, there is a need to develop rapid screening methods based on in silico methods. This study illustrates the application of conceptual Density Functional Theory (DFT) to some carbon nanotubes (CNTs) optimized by means of static DFT calculations. The computational efforts are focused on the geometry of a family of packed narrow-diameter carbon nanotubes (CNTs) formed by units from four to twelve carbons evaluating the strength of the C-C bonds by means of Mayer Bond Orders (MBO). Thus, width and length are geometrical features that might be used to tune the electronic properties of the CNTs. At infinite length, partial semi-conductor characteristics are expected. © 2012 Bentham Science Publishers.

Tuning the electronic properties by width and length modifications of narrow-diameter carbon nanotubes for nanomedicine

KAUST Repository

Poater, Albert

2012-10-01

The distinctive characteristics of nanoparticles, resulting from properties that arise at the nano-scale, underlie their potential applications in the biomedical sector. However, the very same characteristics also result in widespread concerns about the potentially toxic effects of nanoparticles. Given the large number of nanoparticles that are being developed for possible biomedical use, there is a need to develop rapid screening methods based on in silico methods. This study illustrates the application of conceptual Density Functional Theory (DFT) to some carbon nanotubes (CNTs) optimized by means of static DFT calculations. The computational efforts are focused on the geometry of a family of packed narrow-diameter carbon nanotubes (CNTs) formed by units from four to twelve carbons evaluating the strength of the C-C bonds by means of Mayer Bond Orders (MBO). Thus, width and length are geometrical features that might be used to tune the electronic properties of the CNTs. At infinite length, partial semi-conductor characteristics are expected. © 2012 Bentham Science Publishers.

Electron diffraction from carbon nanotubes

International Nuclear Information System (INIS)

Qin, L-C

2006-01-01

The properties of a carbon nanotube are dependent on its atomic structure. The atomic structure of a carbon nanotube can be defined by specifying its chiral indices (u, v), that specify its perimeter vector (chiral vector), with which the diameter and helicity are also determined. The fine electron beam available in a modern transmission electron microscope (TEM) offers a unique probe to reveal the atomic structure of individual nanotubes. This review covers two aspects related to the use of the electron probe in the TEM for the study of carbon nanotubes: (a) to understand the electron diffraction phenomena for inter-pretation of the electron diffraction patterns of carbon nanotubes and (b) to obtain the chiral indices (u, v), of the carbon nanotubes from the electron diffraction patterns. For a nanotube of a given structure, the electron scattering amplitude from the carbon nanotube is first described analytically in closed form using the helical diffraction theory. From a known structure as given by the chiral indices (u, v), its electron diffraction pattern can be calculated and understood. The reverse problem, i.e. assignment of the chiral indices from an electron diffraction pattern of a carbon nanotube, is approached from the relationship between the electron scattering intensity distribution and the chiral indices (u, v). We show that electron diffraction patterns can provide an accurate and unambiguous assignment of the chiral indices of carbon nanotubes. The chiral indices (u, v) can be read indiscriminately with a high accuracy from the intensity distribution on the principal layer lines in an electron diffraction pattern. The symmetry properties of electron diffraction from carbon nanotubes and the electron diffraction from deformed carbon nanotubes are also discussed in detail. It is shown that 2mm symmetry is always preserved for single-walled carbon nanotubes, but it can break down for multiwalled carbon nanotubes under some special circumstances

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.

Electrostatic sensing and electrochemistry with single carbon nanotubes

NARCIS (Netherlands)

Heller, I.

2009-01-01

This thesis describes the experimental study of devices based on single carbon nanotubes in the context of (bio)sensing in aqueous solutions. Carbon nanotubes are cylindrical molecules of sp2- carbon, about one nanometer in diameter and typically several micrometers long, which have semiconducting

Growth of uniform thin-walled carbon nanotubes with spin-coated Fe catalyst and the correlation between the pre-growth catalyst size and the nanotube diameter

International Nuclear Information System (INIS)

Seah, Choon-Ming; Chai, Siang-Piao; Ichikawa, Satoshi; Mohamed, Abdul Rahman

2013-01-01

Single-walled carbon nanotubes (CNTs) and double-walled CNTs with a selectivity of 93 % were obtained by means of the novel homemade iron catalysts which were spin coated on silicon wafer. The average diameters of the iron particles prepared from the colloidal solutions containing 30, 40, 50, 60, and 70 mmol/L of iron nitrate were 8.2, 5.1, 20.8, 32.2, and 34.7 nm, respectively, and growing thin-walled CNTs with the average diameters of 4.1, 2.2, 9.2, 11.1, and 18.1 nm, respectively. The diameters of the CNTs were correlated with the geometric sizes of the pre-growth catalyst particles. Thin-walled CNTs were found to have a catalyst mean diameter-to-CNT average diameter ratio of 2.31. Iron carbide was formed after the growth of CNTs, and it is believed that during the growth of CNTs, carbon source decomposed and deposited on the surface of catalyst, followed by the diffusion of surface carbon into the iron catalyst particles, resulting in carbon supersaturation state before the growth of CNTs.

Extremely high thermal conductivity anisotropy of double-walled carbon nanotubes

Directory of Open Access Journals (Sweden)

Zhaoji Ma

2017-06-01

Full Text Available Based on molecular dynamics simulations, we reveal that double-walled carbon nanotubes can possess an extremely high anisotropy ratio of radial to axial thermal conductivities. The mechanism is basically the same as that for the high thermal conductivity anisotropy of graphene layers - the in-plane strong sp2 bonds lead to a very high intralayer thermal conductivity while the weak van der Waals interactions to a very low interlayer thermal conductivity. However, different from flat graphene layers, the tubular structures of carbon nanotubes result in a diameter dependent thermal conductivity. The smaller the diameter, the larger the axial thermal conductivity but the smaller the radial thermal conductivity. As a result, a DWCNT with a small diameter may have an anisotropy ratio of thermal conductivity significantly higher than that for graphene layers. The extremely high thermal conductivity anisotropy allows DWCNTs to be a promising candidate for thermal management materials.

Layered growth of aligned carbon nanotube arrays by pyrolysis

International Nuclear Information System (INIS)

Zhang Hongrui; Liang Erjun; Ding Pei; Chao Mingju

2003-01-01

Based on the study of reaction temperature and duration of the growth of aligned carbon nanotube arrays, layered aligned multi-wall carbon nanotube (MWNT) films grown directly around a reaction quartz tube in an Ar/H 2 atmosphere by pyrolysis of ferrocene in xylene in a suitable reaction furnace with the help of cobalt powder. The scanning electron microscope and transmission electron microscope images indicated that the obtained arrays were composed of many separated layers with MWNTs. The reaction temperature significantly influenced the alignment of the MWNTs, and an appropriate reaction temperature range for growth was 800-900 deg. C. The diameter of the carbon nanotube increased from 46 to 75 nm with the growth temperature. Besides temperature, the reaction duration influenced the length of the well-aligned carbon nanotubes. There was no significant relation between the growth time and the diameter of the carbon nanotubes in the array

Structure of carbon and boron nitride nanotubes produced by mechano-thermal process

International Nuclear Information System (INIS)

Chen, Y.; Conway, M.; FitzGerald, J.; Williams, J.S.; Chadderton, L.T.

2002-01-01

Full text: Structure of carbon and boron nitride (BN) nanotubes produced by mechano-thermal process has been investigated by using field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) including high resolution TEM. FESEM and TEM reveal that nanotubes obtained have a diameter varying from several nm to 200 nm and a length of several micrometers. The size of the nanotubes appears to depend on both milling and heating conditions. Many nanotubes are extruded from particle clusters, implying a special growth mechanism. TEM reveals single- and multi- wall tubular structures and different caps. Bomboo-type nanotubes containing small metal particles inside are also observed in both carbon and BN tubes. This investigation shows that nanotubes with controlled size and structure could be produced by the mechano-thermal process

EB treatment of carbon nanotube-reinforced polymer composites

International Nuclear Information System (INIS)

Szebenyi, G.; Romhany, G.; Czvikovszky, T.; Vajna, B.

2011-01-01

Complete text of publication follows. A small amount - less than 0.5% - carbon nanotube reinforcement may improve significantly the mechanical properties of epoxy based composite materials. The basic technical problem is on one side the dispersion of the nanotubes into the viscous matrix resin. Namely the fine, powder-like - less than 100 nanometer diameter - nanotubes are prone to form aggregates. On the other side, the good connection between the nanofiber and matrix, - which is determining the success of the reinforcement, - requires some efficient adhesion promoting treatment. After an elaborate masterbatch mixing technology we applied Electron Beam treatment of epoxy-matrix polymer composites containing carbon nanotubes in presence of vinylester resins. The Raman spectra of vinylester-epoxy mixtures treated by an 8 MeV EB showed the advantage of the electron treatment. Even in the case of partially immiscible epoxy and vinylester resins, the anchorage of carbon nanotubes reflects improvement if a reasonable 25 kGy EB dose is applied. Atomic Force Microscopy as well as mechanical tests on flexural and impact properties confirm the benefits of EB treatment. Simultaneous application of multiwall carbon nanotubes and 'conventional' carbon fibers as reinforcement in vinylester modified epoxies results in new types of hybrid nanocomposites as engineering materials. The bending- and interlaminar properties of such hybrid systems showed the beneficial effect of the EB treatment. Acknowledgement: This work has been supported by the New Hungary Development Plan (Project ID: TAMOP-4.2.1/B-09/1/KMR-2010-0002).

Modelling the relative stability of carbon nanotubes exposed to environmental adsorbates and air

International Nuclear Information System (INIS)

Barnard, Amanda S

2009-01-01

In parallel with the development of technological applications for carbon nanotubes, issues related to toxicology and environmental impact are also under increased scrutiny. It is clear from the available literature that the integrity of future carbon nanotube-based devices, our ability to anticipate failure of these devices, and our ability to manage the toxicological and environmental impacts require a detailed understanding of the stability of pure and functionalized carbon nanotubes under a full range of environmental conditions. Motivated by this endeavour, the present study uses a general thermodynamic model to predict the relative stability of carbon nanotubes exposed to a variety of atmospheric adsorbates, and uses them to examine the stability of nanotubes in air, as a function of the relative humidity. In general the results indicate that the adsorption of a sparse coverage of air is thermodynamically favoured, depending on the humidity, and the stability of small diameter nanotubes may be improved by exposure to humid air.

Carbon Nanotube Templated Microfabrication of Porous Silicon-Carbon Materials

Science.gov (United States)

Song, Jun; Jensen, David; Dadson, Andrew; Vail, Michael; Linford, Matthew; Vanfleet, Richard; Davis, Robert

2010-10-01

Carbon nanotube templated microfabrication (CNT-M) of porous materials is demonstrated. Partial chemical infiltration of three dimensional carbon nanotube structures with silicon resulted in a mechanically robust material, precisely structured from the 10 nm scale to the 100 micron scale. Nanoscale dimensions are determined by the diameter and spacing of the resulting silicon/carbon nanotubes while the microscale dimensions are controlled by lithographic patterning of the CNT growth catalyst. We demonstrate the utility of this hierarchical structuring approach by using CNT-M to fabricate thin layer chromatography (TLC) separations media with precise microscale channels for fluid flow control and nanoscale porosity for high analyte capacity.

New approach to synthesis of carbon nanotubes

International Nuclear Information System (INIS)

Ha, Jong Keun; Choi, Kyo Hong; Cho, Kwon Koo; Kim, Ki Won; Nam, Tae Hyun; Ahn, Hyo Jun; Ahn, Jou Hyun; Cho, Gyu Bong

2007-01-01

Carbon nanotubes (CNTs) have been synthesized through chemical vapor deposition in argon gas atmosphere using Fe-2.5%Mo alloyed nanoparticles as a catalyst and H 2 /CH 4 gas mixture as a reaction gas. Fe-2.5 wt.%Mo alloyed nanoparticles with average diameter of 7, 20, 45 and 85 nm are prepared by the chemical vapor condensation process using the pyrolysis of iron pentacarbonyl (Fe(CO) 5 ) and molybdenum hexacarbonyl (Mo(CO) 6 ). The morphologies of the CNTs are controlled by adjusting the nanoparticle size, reaction gas ratio and reaction temperature. With decreasing nanoparticle size under the same experimental conditions, the degree of crystalline perfection increases gradually and the morphologies of the carbon nanotubes vary from multi wall carbon nanotubes to single wall carbon nanotubes. Also, the ratio of reaction gas has an effect on the morphology and the degree of crystallinity of CNTs. In this work, it is suggested that morphology, diameter and degree of crystallinity of CNTs could be controlled by adjusting the reaction gas ratio, reaction temperature and catalyst size

Atomic Structure and Energy Distribution of Collapsed Carbon Nanotubes of Different Chiralities

Directory of Open Access Journals (Sweden)

Julia A. Baimova

2015-01-01

Full Text Available For carbon nanotubes of sufficiently large diameter at sufficiently low temperature, due to the action of the van der Waals forces, the ground state is a bilayer graphene with closed edges, the so-called collapsed configuration. Molecular dynamics simulation of collapsed carbon nanotubes is performed. The effect of length, diameter, and chirality of the nanotubes on their properties is investigated. It is shown that collapsed nanotubes after relaxation have rippled structure which is strongly dependent on the nanotube chirality. The structural properties are studied by calculating the radial distribution function and energy distribution along various regions in the collapsed carbon nanotubes.

Intrinsic Chirality Origination in Carbon Nanotubes.

Science.gov (United States)

Pierce, Neal; Chen, Gugang; P Rajukumar, Lakshmy; Chou, Nam Hawn; Koh, Ai Leen; Sinclair, Robert; Maruyama, Shigeo; Terrones, Mauricio; Harutyunyan, Avetik R

2017-10-24

Elucidating the origin of carbon nanotube chirality is key for realizing their untapped potential. Currently, prevalent theories suggest that catalyst structure originates chirality via an epitaxial relationship. Here we studied chirality abundances of carbon nanotubes grown on floating liquid Ga droplets, which excludes the influence of catalyst features, and compared them with abundances grown on solid Ru nanoparticles. Results of growth on liquid droplets bolsters the intrinsic preference of carbon nuclei toward certain chiralities. Specifically, the abundance of the (11,1)/χ = 4.31° tube can reach up to 95% relative to (9,4)/χ = 17.48°, although they have exactly the same diameter, (9.156 Å). However, the comparative abundances for the pair, (19,3)/χ = 7.2° and (17,6)/χ = 14.5°, with bigger diameter, (16.405 Å), fluctuate depending on synthesis temperature. The abundances of the same pairs of tubes grown on floating solid polyhedral Ru nanoparticles show completely different trends. Analysis of abundances in relation to nucleation probability, represented by a product of the Zeldovich factor and the deviation interval of a growing nuclei from equilibrium critical size, explain the findings. We suggest that the chirality in the nanotube in general is a result of interplay between intrinsic preference of carbon cluster and induction by catalyst structure. This finding can help to build the comprehensive theory of nanotube growth and offers a prospect for chirality-preferential synthesis of carbon nanotubes by the exploitation of liquid catalyst droplets.

Confinement in single walled carbon nanotubes investigated by spectroscopic ellipsometry

International Nuclear Information System (INIS)

Battie, Y.; Jamon, D.; Lauret, J.S.; Gu, Q.; Gicquel-Guézo, M.; En Naciri, A.; Loiseau, A.

2014-01-01

Thick films of single walled carbon nanotubes (SWCNTs) with different diameter and chirality distributions are characterized by combining transmission electron microscopy and spectroscopic ellipsometry. The dependence of the dielectric function with the increase of the SWCNT diameter occurs with a drastic redshift of the S 11 , S 22 and M 11 transition energies. The transfer integral parameter γ 0 of SWCNT is also evaluated and analyzed. We demonstrate that parts of the optical properties of SWCNTs are attributed to a one dimensional confinement effect. - Highlights: • Ellipsometric measurements are performed on carbon nanotube thick films. • The complex dielectric functions of conventional carbon nanotubes are given. • Confinement effects explain the variations of dielectric function of nanotubes

Thermodynamics and vibrational study of hydrogenated carbon nanotubes: A DFT study

Science.gov (United States)

Khalil, Rana M. Arif; Hussain, Fayyaz; Rana, Anwar Manzoor; Imran, Muhammad

2018-02-01

Thermodynamic stability of the hydrogenated carbon nanotubes has been explored in the chemisorption limit. Statistical physics and density functional theory calculations have been used to predict hydrogen release temperatures at standard pressure in zigzag and armchair carbon nanotubes. It is found that hydrogen release temperatures decrease with increase in diameters of hydrogenated zigzag carbon nanotubes (CNTs) but opposite trend is noted in armchair CNTs at standard pressure of 1 bar. The smaller diameter hydrogenated zigzag CNTs have large values of hydrogen release temperature due to the stability of Csbnd H bonds. The vibrational density of states for hydrogenated carbon nanotubes have been calculated to confirm the Csbnd H stretching mode caused by sp3 hybridization.

Structural properties of carbon nanotubes derived from 13C NMR

KAUST Repository

Abou-Hamad, E.

2011-10-10

We present a detailed experimental and theoretical study on how structural properties of carbon nanotubes can be derived from 13C NMR investigations. Magic angle spinning solid state NMR experiments have been performed on single- and multiwalled carbon nanotubes with diameters in the range from 0.7 to 100 nm and with number of walls from 1 to 90. We provide models on how diameter and the number of nanotube walls influence NMR linewidth and line position. Both models are supported by theoretical calculations. Increasing the diameter D, from the smallest investigated nanotube, which in our study corresponds to the inner nanotube of a double-walled tube to the largest studied diameter, corresponding to large multiwalled nanotubes, leads to a 23.5 ppm diamagnetic shift of the isotropic NMR line position δ. We show that the isotropic line follows the relation δ = 18.3/D + 102.5 ppm, where D is the diameter of the tube and NMR line position δ is relative to tetramethylsilane. The relation asymptotically tends to approach the line position expected in graphene. A characteristic broadening of the line shape is observed with the increasing number of walls. This feature can be rationalized by an isotropic shift distribution originating from different diamagnetic shielding of the encapsulated nanotubes together with a heterogeneity of the samples. Based on our results, NMR is shown to be a nondestructive spectroscopic method that can be used as a complementary method to, for example, transmission electron microscopy to obtain structural information for carbon nanotubes, especially bulk samples.

Nanotube cathodes.

Energy Technology Data Exchange (ETDEWEB)

Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

2006-11-01

had a thin coating of glassy carbon surrounding them in a sheath-like manner. This glassy carbon, or nano-crystalline graphite, is likely to be a poor conductor due to phonon scattering, and should actually be deleterious for extracting electrons with electric fields. While we did not achieve the field emission reported for single-wall carbon nanotubes that spurred the idea for this project, at the year's very end, we had a breakthrough in materials growth and learned to control the growth of very-small diameter nanotubes ranging from 1.4 to 7 nm. The 1.4-nm nanotubes are single-walled and grow at only 530 C. This is the lowest temperature known to result in single-wall carbon nanotubes, and may be very important for many applications that where certain substrates could not be used due to the high temperatures commonly used for CNT growth. Critically important for field emission, these small diameter nanotubes, consisting of only a few concentric graphene cylindrical walls, do not show the presence of a poorly-conductive sheath material. Therefore, these nanotubes will almost definitely have superior field emission properties to those we already measured, and it is possible that they could provide the necessary field emission to make this project successful. Controlled spacing and lengths of these single-wall nanotubes have yet to be explored, along with correlating their structures to their improved field emission. Unfortunately, we did not discover the methods to grow these highly-crystalline and small diameter CNTs until late in the year. Since we did not achieve the necessary emission properties by mid-year, the project was ''prematurely'' terminated prior to the start of the second year. However, it should be noted that with the late developments, this work has not hit the proverbial ''brick wall''. Clearly the potential still exists to reproduce and even exceed the high emission results reported for randomly

Nanotube cathodes

International Nuclear Information System (INIS)

Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

2006-01-01

had a thin coating of glassy carbon surrounding them in a sheath-like manner. This glassy carbon, or nano-crystalline graphite, is likely to be a poor conductor due to phonon scattering, and should actually be deleterious for extracting electrons with electric fields. While we did not achieve the field emission reported for single-wall carbon nanotubes that spurred the idea for this project, at the year's very end, we had a breakthrough in materials growth and learned to control the growth of very-small diameter nanotubes ranging from 1.4 to 7 nm. The 1.4-nm nanotubes are single-walled and grow at only 530 C. This is the lowest temperature known to result in single-wall carbon nanotubes, and may be very important for many applications that where certain substrates could not be used due to the high temperatures commonly used for CNT growth. Critically important for field emission, these small diameter nanotubes, consisting of only a few concentric graphene cylindrical walls, do not show the presence of a poorly-conductive sheath material. Therefore, these nanotubes will almost definitely have superior field emission properties to those we already measured, and it is possible that they could provide the necessary field emission to make this project successful. Controlled spacing and lengths of these single-wall nanotubes have yet to be explored, along with correlating their structures to their improved field emission. Unfortunately, we did not discover the methods to grow these highly-crystalline and small diameter CNTs until late in the year. Since we did not achieve the necessary emission properties by mid-year, the project was ''prematurely'' terminated prior to the start of the second year. However, it should be noted that with the late developments, this work has not hit the proverbial ''brick wall''. Clearly the potential still exists to reproduce and even exceed the high emission results reported for randomly-oriented and curly single-wall carbon nanotubes, both

Molecular dynamics simulations of proton-ordered water confined in low-diameter carbon nanotubes.

Science.gov (United States)

Li, Shujuan; Schmidt, Burkhard

2015-03-21

The present work deals with molecular dynamics simulations of water confined in single-walled carbon nanotubes (CNTs), with emphasis on the proton-ordering of water and its polarization. First, the water occupancy of open-ended armchair and zigzag CNTs immersed in water under ambient NPT conditions is calculated for various water models, and for varying Lennard-Jones parameters of the water-carbon interaction. As a function of the CNT diameter, the water density displays several oscillations before converging to the bulk value. Based on these results, the water structures encapsulated in 10 nm long armchair CNTs (n,n) with 5 ≤ n ≤ 10, are investigated under NVT conditions. Inside the smallest nanotubes (n = 5, 6) highly ferroelectric (FE), quasi-one-dimensional water chains are found while inside the other CNTs water molecules assemble into single-walled ice nanotubes (INTs). There are several, near-degenerate minimum energy INT structures: single helical structures were found for 7 ≤ n ≤ 10, in all cases in FE arrangement. In addition, a double helical INT structure was found for n = 8 with an even higher polarization. Prism-like structures were found only for 8 ≤ n ≤ 10 with various FE, ferrielectric (FI), and antiferroelectric (AF, n = 9, 10) proton ordering. The coexistence of the nearly iso-energetic FE, FI, and AF INT structures separated by high barriers renders the molecular dynamics highly metastable, typically with nanosecond timescales at room temperature. Hence, the replica exchange simulation method is used to obtain populations of different INT states at finite temperatures. Many of the FE INT structures confined in low-diameter CNTs are still prevalent at room temperature. Both helix-helix and helix-prism structural transitions are detected which can be either continuous (around 470 K for n = 8) or discontinuous (at 218 K for n = 9). Also melting-like transitions are found in which the INT structures are disrupted leading to a loss of FE

Electrical measurements on submicronic synthetic conductors : carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Langer, L [Unite de Physico-Chimie et de Physique des Materiaux, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium); Stockman, L [Lab. voor Vaste Stof-Fysika en Magnetisme, Katholieke Univ. Leuven (Belgium); Heremans, J P [Physics Dept., General Motors Research, Warren, MI (United States); Bayot, V [Unite de Physico-Chimie et de Physique des Materiaux, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium); Olk, C H [Physics Dept., General Motors Research, Warren, MI (United States); Haesendonck, C van [Lab. voor Vaste Stof-Fysika en Magnetisme, Katholieke Univ. Leuven (Belgium); Bruynseraede, Y [Lab. voor Vaste Stof-Fysika en Magnetisme, Katholieke Univ. Leuven (Belgium); Issi, J P [Unite de Physico-Chimie et de Physique des Materiaux, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium)

1995-03-15

The synthesis of very small samples has raised the need for a drastic miniaturization of the classical four-probe technique in order to realize electrical resistance measurements. Two methods to realize electrical contacts on very small fibers are described here. Using classical photolithography the electrical resistivity of a submicronic catalytic chemical vapour deposited filament is estimated. Scanning tunneling microscopy (STM) lithography allowed to attach small gold contacts to a small bundle (diameter 50 nm) of carbon nanotubes. This bundle is found to exhibit a semimetallic behavior at higher temperature and an unexpected drop of the electrical resistivity at lower temperature. (orig.)

Optical properties of carbon nanotubes

Science.gov (United States)

Chen, Gugang

This thesis addresses the optical properties of novel carbon filamentary nanomaterials: single-walled carbon nanotubes (SWNTs), double-walled carbon nanotubes (DWNTs), and SWNTs with interior C60 molecules ("peapods"). Optical reflectance spectra of bundled SWNTs are discussed in terms of their electronic energy band structure. An Effective Medium Model for a composite material was found to provide a reasonable description of the spectra. Furthermore, we have learned from optical absorption studies of DWNTs and C60-peapods that the host tube and the encapsulant interact weakly; small shifts in interband absorption structure were observed. Resonant Raman scattering studies on SWNTs synthesized via the HiPCO process show that the "zone-folding" approximation for phonons and electrons works reasonably well, even for small diameter (d effect, rather than the vdW interaction. Finally, we studied the chemical doping of DWNTs, where the dopant (Br anions) is chemically bound to the outside of the outer tube. The doped DWNT system is a model for a cylindrical molecular capacitor. We found experimentally that 90% of the positive charge resides on the outer tube, so that most of electric field on the inner tube is screened, i.e., we have observed a molecular Faraday cage effect. A self-consistent theoretical model in the tight-binding approximation with a classical electrostatic energy term is in good agreement with our experimental results.

Density functional theory calculations of energy-loss carbon near-edge spectra of small diameter armchair and zigzag nanotubes: Core-hole, curvature, and momentum-transfer orientation effects

International Nuclear Information System (INIS)

Titantah, J.T.; Lamoen, D.; Jorissen, K.

2004-01-01

We perform density functional theory calculations on a series of armchair and zigzag nanotubes of diameters less than 1 nm using the all-electron full-potential(-linearized)-augmented-plane-wave method. Emphasis is laid on the effects of curvature, the electron-beam orientation, and the inclusion of the core hole on the carbon electron-energy-loss K edge. The electron-energy-loss near-edge spectra of all the studied tubes show strong curvature effects compared to that of flat graphene. The curvature-induced π-σ hybridization is shown to have a more drastic effect on the electronic properties of zigzag tubes than on those of armchair tubes. We show that the core-hole effect must be accounted for in order to correctly reproduce electron-energy-loss measurements. We also find that the energy-loss near-edge spectra of these carbon systems are dominantly dipole selected and that they can be expressed simply as a proportionality with the local momentum projected density of states, thus portraying the weak energy dependence of the transition matrix elements. Compared to graphite, we report a reduction in the anisotropy as seen on the energy-loss near-edge spectra of carbon nanotubes

Discovery of carbon nanotubes. Sara ni carbon nanotube e

Energy Technology Data Exchange (ETDEWEB)

Iijima, S

1994-01-20

This paper describes the following matters on carbon nanotubes (CNt): CNt is discovered in carbon deposits generated in the tip of a negative electrode during DC arc discharge between carbon electrodes. CNt has a construction in which cylinders made of normally several layers are superposed, based on cylindrical crystals in a single layer with six-member rings of carbon atoms laid out. Spiral arrangement of carbon six-member rings has been discovered in the single-layered crystals. Five-member rings exist in a location where the CNt tip is closed, and seven-member rings in a location where the CNt presents a saddle-like curve, without exceptions. It is introduced theoretically that the electronic structure of the single-layered CNt depends on the cylinder diameter and spiral pitch. Replacing part of the carbon negative electrode with iron, and vaporizing iron and carbon simultaneously through arc discharge can result in a single-layered CNt with a diameter of 1 nm. Heating the CNt deposited with metallic lead in an oxygen atmosphere can form CNt containing lead compounds. 19 refs., 9 figs.

Four- and eight-membered rings carbon nanotubes: A new class of carbon nanomaterials

Directory of Open Access Journals (Sweden)

Fangfang Li

2018-06-01

Full Text Available A new class of carbon nanomaterials composed of alternating four- and eight-membered rings is studied by density functional theory (DFT, including single-walled carbon nanotubes (SWCNTs double-walled carbon nanotubes (DWCNTs and triple-walled CNTs (TWCNTs. The analysis of geometrical structure shows that carbon atoms’ hybridization in novel carbon tubular clusters (CTCs and the corresponding carbon nanotubes (CNTs are both sp2 hybridization; The thermal properties exhibit the high stability of these new CTCs. The results of energy band and density of state (DOS indicate that the electronic properties of CNTs are independent of their diameter, number of walls and chirality, exhibit obvious metal properties. Keywords: Four- and eight-membered rings, Carbon nanotubes, Stability, Electronic properties

Pseudo-topotactic conversion of carbon nanotubes to T-carbon nanowires under picosecond laser irradiation in methanol.

Science.gov (United States)

Zhang, Jinying; Wang, Rui; Zhu, Xi; Pan, Aifei; Han, Chenxiao; Li, Xin; Dan Zhao; Ma, Chuansheng; Wang, Wenjun; Su, Haibin; Niu, Chunming

2017-09-25

Pseudo-topotactic conversion of carbon nanotubes into one-dimensional carbon nanowires is a challenging but feasible path to obtain desired diameters and morphologies. Here, a previously predicted but experimentally unobserved carbon allotrope, T-carbon, has been produced from pseudo-topotactic conversion of a multi-walled carbon nanotube suspension in methanol by picosecond pulsed-laser irradiation. The as-grown T-carbon nanowires have the same diameter distribution as pristine carbon nanotubes, and have been characterized by high-resolution transmission electron microscopy, fast Fourier transform, electron energy loss, ultraviolet-visible, and photoluminescence spectroscopies to possess a diamond-like lattice, where each carbon is replaced by a carbon tetrahedron, and a lattice constant of 7.80 Å. The change in entropy from carbon nanotubes to T-carbon reveals the phase transformation to be first order in nature. The computed electronic band structures and projected density of states are in good agreement with the optical absorption and photoluminescence spectra of the T-carbon nanowires.T-carbon is a previously predicted but so far unobserved allotrope of carbon, with a crystal structure similar to diamond, but with each atomic lattice position replaced by a carbon tetrahedron. Here, the authors produce T-carbon nanowires via laser-irradiating a suspension of carbon nanotubes in methanol.

Manufacturing High-Quality Carbon Nanotubes at Lower Cost

Science.gov (United States)

Benavides, Jeanette M.; Lidecker, Henning

2004-01-01

A modified electric-arc welding process has been developed for manufacturing high-quality batches of carbon nanotubes at relatively low cost. Unlike in some other processes for making carbon nanotubes, metal catalysts are not used and, consequently, it is not necessary to perform extensive cleaning and purification. Also, unlike some other processes, this process is carried out at atmospheric pressure under a hood instead of in a closed, pressurized chamber; as a result, the present process can be implemented more easily. Although the present welding-based process includes an electric arc, it differs from a prior electric-arc nanotube-production process. The welding equipment used in this process includes an AC/DC welding power source with an integral helium-gas delivery system and circulating water for cooling an assembly that holds one of the welding electrodes (in this case, the anode). The cathode is a hollow carbon (optionally, graphite) rod having an outside diameter of 2 in. (approximately equal to 5.1 cm) and an inside diameter of 5/8 in. (approximately equal to 1.6 cm). The cathode is partly immersed in a water bath, such that it protrudes about 2 in. (about 5.1 cm) above the surface of the water. The bottom end of the cathode is held underwater by a clamp, to which is connected the grounding cable of the welding power source. The anode is a carbon rod 1/8 in. (approximately equal to 0.3 cm) in diameter. The assembly that holds the anode includes a thumbknob- driven mechanism for controlling the height of the anode. A small hood is placed over the anode to direct a flow of helium downward from the anode to the cathode during the welding process. A bell-shaped exhaust hood collects the helium and other gases from the process. During the process, as the anode is consumed, the height of the anode is adjusted to maintain an anode-to-cathode gap of 1 mm. The arc-welding process is continued until the upper end of the anode has been lowered to a specified height

Variable electron beam diameter achieved by a titanium oxide/carbon nanotube hetero-structure suitable for nanolithography

International Nuclear Information System (INIS)

Abdi, Yaser; Barati, Fatemeh

2013-01-01

We report the fabrication of a titanium oxide/carbon nanotube based field emission device suitable for nanolithography and fabrication of transistors. The growth of carbon nanotubes (CNTs) is performed on silicon substrates using a plasma-enhanced chemical vapor deposition method. The vertically grown CNTs are encapsulated by titanium oxide (TiO 2 ) using an atmospheric pressure chemical vapor deposition system. Field emission from the CNTs is realized by mechanical polishing of the prepared structure. Possible applications of such nanostructures as a lithography tool with variable electron beam diameter has been investigated. The obtained results show that a spot size of less than 30 nm can be obtained by applying the proper voltage on TiO 2 surrounding gate. Electrical measurements of the fabricated device confirm the capability of the structure for fabrication of field emission based field effect transistors. By a voltage applied between the gate and the cathode electrode, the emission current from CNTs shows a significant drop, indicating proper control of the gate on the emission current. (paper)

Structure and Characterization of Vertically Aligned Single-Walled Carbon Nanotube Bundles

International Nuclear Information System (INIS)

Marquez, F.; Morant, C.; Elizalde, E.; Roque-Malherbe, R.; Lopez, V.; Zamora, F.; Domingo, C.

2010-01-01

Arrays of vertically aligned single-walled carbon nanotube bundles, SWCNTs, have been synthesized by simple alcohol catalytic chemical vapor deposition process, carried out at 800 degree C. The formed SWCNTs are organized in small groups perpendicularly aligned and attached to the substrate. These small bundles show a constant diameter of ca. 30 nm and are formed by the adhesion of no more than twenty individual SWCNTs perfectly aligned along their length.

Four- and eight-membered rings carbon nanotubes: A new class of carbon nanomaterials

Science.gov (United States)

Li, Fangfang; Lu, Junzhe; Zhu, Hengjiang; Lin, Xiang

2018-06-01

A new class of carbon nanomaterials composed of alternating four- and eight-membered rings is studied by density functional theory (DFT), including single-walled carbon nanotubes (SWCNTs) double-walled carbon nanotubes (DWCNTs) and triple-walled CNTs (TWCNTs). The analysis of geometrical structure shows that carbon atoms' hybridization in novel carbon tubular clusters (CTCs) and the corresponding carbon nanotubes (CNTs) are both sp2 hybridization; The thermal properties exhibit the high stability of these new CTCs. The results of energy band and density of state (DOS) indicate that the electronic properties of CNTs are independent of their diameter, number of walls and chirality, exhibit obvious metal properties.

Structure, electronic properties, and aggregation behavior of hydroxylated carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

López-Oyama, A. B.; Silva-Molina, R. A.; Ruíz-García, J.; Guirado-López, R. A., E-mail: guirado@ifisica.uaslp.mx [Instituto de Física “Manuel Sandoval Vallarta,” Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí (Mexico); Gámez-Corrales, R. [Departamento de Física, Universidad de Sonora, Apartado Postal 5-088, 83190, Hermosillo, Sonora (Mexico)

2014-11-07

We present a combined experimental and theoretical study to analyze the structure, electronic properties, and aggregation behavior of hydroxylated multiwalled carbon nanotubes (OH–MWCNT). Our MWCNTs have average diameters of ∼2 nm, lengths of approximately 100–300 nm, and a hydroxyl surface coverage θ∼0.1. When deposited on the air/water interface the OH–MWCNTs are partially soluble and the floating units interact and link with each other forming extended foam-like carbon networks. Surface pressure-area isotherms of the nanotube films are performed using the Langmuir balance method at different equilibration times. The films are transferred into a mica substrate and atomic force microscopy images show that the foam like structure is preserved and reveals fine details of their microstructure. Density functional theory calculations performed on model hydroxylated carbon nanotubes show that low energy atomic configurations are found when the OH groups form molecular islands on the nanotube's surface. This patchy behavior for the OH species is expected to produce nanotubes having reduced wettabilities, in line with experimental observations. OH doping yields nanotubes having small HOMO–LUMO energy gaps and generates a nanotube → OH direction for the charge transfer leading to the existence of more hole carriers in the structures. Our synthesized OH–MWCNTs might have promising applications.

Thermodynamic model for growth mechanisms of multiwall carbon nanotubes

Science.gov (United States)

Kaatz, F. H.; Siegal, M. P.; Overmyer, D. L.; Provencio, P. P.; Tallant, D. R.

2006-12-01

Multiwall carbon nanotubes are grown via thermal chemical vapor deposition between temperatures of 630 and 830°C using acetylene in nitrogen as the carbon source. This process is modeled using classical thermodynamics to explain the total carbon deposition as a function of time and temperature. An activation energy of 1.60eV is inferred for nanotube growth after considering the carbon solubility term. Scanning electron microscopy shows growth with diameters increasing linearly with time. Transmission electron microscopy and Raman spectroscopy show multiwall nanotubes surrounded by a glassy-carbon sheath, which grows with increasing wall thickness as growth temperatures and times rise.

Growth of highly oriented carbon nanotubes by plasma-enhanced hot filament chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Huang, Z.P.; Xu, J.W.; Ren, Z.F.; Wang, J.H. [Materials Synthesis Laboratory, Departments of Physics and Chemistry, and Center for Advanced Photonic and Electronic Materials (CAPEM), State University of New York at Buffalo, Buffalo, New York 14260 (United States); Siegal, M.P.; Provencio, P.N. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)

1998-12-01

Highly oriented, multiwalled carbon nanotubes were grown on polished polycrystalline and single crystal nickel substrates by plasma enhanced hot filament chemical vapor deposition at temperatures below 666 {degree}C. The carbon nanotubes range from 10 to 500 nm in diameter and 0.1 to 50 {mu}m in length depending on growth conditions. Acetylene is used as the carbon source for the growth of the carbon nanotubes and ammonia is used for dilution gas and catalysis. The plasma intensity, acetylene to ammonia gas ratio, and their flow rates, etc. affect the diameters and uniformity of the carbon nanotubes. {copyright} {ital 1998 American Institute of Physics.}

Carbon nanotube: the inside story.

Science.gov (United States)

Ando, Yoshinori

2010-06-01

Carbon nanotubes (CNTs) were serendipitously discovered as a byproduct of fullerenes by direct current (DC) arc discharge; and today this is the most-wanted material in the nanotechnology research. In this brief review, I begin with the history of the discovery of CNTs and focus on CNTs produced by arc discharge in hydrogen atmosphere, which is little explored outside my laboratory. DC arc discharge evaporation of pure graphite rod in pure hydrogen gas results in multi-walled carbon nanotubes (MWCNTs) of high crystallinity in the cathode deposit. As-grown MWCNTs have very narrow inner diameter. Raman spectra of these MWCNTs show high-intensity G-band, unusual high-frequency radial breathing mode at 570 cm(-1), and a new characteristic peak near 1850 cm(-1). Exciting carbon nanowires (CNWs), consisting of a linear carbon chain in the center of MWCNTs are also produced. Arc evaporation of graphite rod containing metal catalysts results in single-wall carbon nanotubes (SWCNTs) in the whole chamber like macroscopic webs. Two kinds of arc method have been developed to produce SWCNTs: Arc plasma jet (APJ) and Ferrum-Hydrogen (FH) arc methods. Some new purification methods for as-produced SWCNTs are reviewed. Finally, double-walled carbon nanotubes (DWCNTs) are also described.

Effect of Length, Diameter, Chirality, Deformation, and Strain on Contact Thermal Conductance between Single Wall Carbon Nanotubes

Science.gov (United States)

Varshney, Vikas; Lee, Jonghoon; Brown, Joshua S.; Farmer, Barry L.; Voevodin, Andrey A.; Roy, Ajit K.

2018-04-01

Thermal energy transfer across physically interacting single-wall carbon nanotube (SWCNT) interconnects has been investigated using non-equilibrium molecular dynamics simulations. The role of various geometrical and structural (length, diameter, chirality) as well as external (deformation and strain) carbon nanotube (CNT) parameters has been explored to estimate total as well as area-normalized thermal conductance across cross-contact interconnects. It is shown that the CNT aspect ratio and degree of lateral as well as tensile deformation play a significant role in determining the extent of thermal energy exchange across CNT contacts, while CNT chirality has a negligible influence on thermal transport. Depending on the CNT diameter, aspect ratio, and degree of deformation at the contact interface, the thermal conductance values can vary significantly –by more than an order of magnitude for total conductance and a factor of 3 to 4 for area-normalized conductance. The observed trends are discussed from the perspective of modulation in number of low frequency out-of-plane (transverse, flexural, and radial) phonons that transmit thermal energy across the contact and govern the conductance across the interface. The established general dependencies for phonon governed thermal transport at CNT contacts are anticipated to help design and performance prediction of CNT-based flexible nanoelectronic devices, where CNT-CNT contact deformation and strain are routinely encountered during device operations.

Preparation of carbon nanotubes from vacuum pyrolysis of polycarbosilane

International Nuclear Information System (INIS)

Jou, S.; Hsu, C.K.

2004-01-01

Carbon nanotubes (CNTs) were synthesized by vacuum pyrolysis of two types of polycarbosilane (PCS) with iron nano-particles between 800 and 1100 deg. C. Straight nanotubes were obtained from low molecular weight (990 g/mol) PCS whereas curled nanotubes were derived from medium molecular weight (1290 g/mol) PCS. Diameters of these straight and curled nanotubes were between 5 and 20 nm. The mechansim of condensed phase growth of carbon nanotubes was discussed. Electron emission capability of these carbon nanotubes increased with their pyrolyzing temperature. The electric fields required to emit a current density of 10 -2 A/cm 2 from the straight nanotubes being pyrolyzed at 800, 900, 1000, and 1100 deg. C were 1.17, 0.73, 0.67, and 0.33 V/μm, respectively

Adhered Supported Carbon Nanotubes

International Nuclear Information System (INIS)

Johnson, Dale F.; Craft, Benjamin J.; Jaffe, Stephen M.

2001-01-01

Carbon nanotubes (NTs) in excess of 200 μm long are grown by catalytic pyrolysis of hydrocarbon vapors. The nanotubes grow continuously without the typical extinction due to catalyst encapsulation. A woven metal mesh supports the nanotubes creating a metal supported nanotube (MSNT) structure. The 140 μm wide mesh openings are completely filled by 70 nm diameter multiwalled nanotubes (MWNTs). The MWNTs are straight, uniform and highly crystalline. Their wall thickness is about 10 nm (30 graphite layers). The adherent NTs are not removed from the support in a Scotch tape pull test. A 12.5 cm 2 capacitor made from two MSNT structures immersed in 1 M KCl has a capacitance of 0.35 F and an equivalent series resistance of 0.18 Ω. Water flows through the MSNT at a flow velocity of 1 cm/min with a pressure drop of 15 inches of water. With the support removed, the MWNTs naturally form a carbon nanocomposite (CNC) paper with a specific area of 80 m 2 /gm, a bulk density of 0.21 g/cm 3 , an open pore fraction of 0.81, and a resistivity of 0.16 Ω-cm

A fabrication method for field emitter array of carbon nanotubes with improved carbon nanotube rooting

Energy Technology Data Exchange (ETDEWEB)

Chouhan, V., E-mail: vchouhan@post.kek.jp [School of High Energy Accelerator, The Graduate University for Advanced Studies, Tsukuba 305-0801 (Japan); Noguchi, T. [High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Kato, S. [School of High Energy Accelerator, The Graduate University for Advanced Studies, Tsukuba 305-0801 (Japan); High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan)

2015-11-30

We have developed a technique for fabrication of a field emitter array (FEA) of carbon nanotubes (CNTs) to obtain a high emission current along with a high current density. The FEA was prepared with many small equidistant circular emitters of randomly oriented multiwall carbon nanotubes. The fabrication of a FEA substrate followed with deposition of titanium nitride (TiN) film on a tantalum (Ta) substrate and circular titanium (Ti) islands on the TiN coated Ta substrate in a DC magnetron sputtering coater. CNTs were dispersed on the substrate and rooted into the circular Ti islands at a high temperature to prepare an array of circular emitters of CNTs. The TiN film was applied on a Ta substrate to make a reaction barrier between the Ta substrate and CNTs in order to root CNTs only into the Ti islands without a reaction with the Ta substrate at the high temperature. A high emission current of 31.7 mA with an effective current density of 34.5 A/cm{sup 2} was drawn at 6.5 V/μm from a FEA having 130 circular emitters in a diameter of 50 μm and with a pitch of 200 μm. The high emission current was ascribed to the good quality rooting of CNTs into the Ti islands and an edge effect, in which a high emission current was expected from the peripheries of the circular emitters. - Highlights: • We developed a method to fabricate a field emitter array of carbon nanotubes (CNTs). • CNT rooting into array of titanium islands was improved at a high temperature. • Titanium nitride film was used to stop reaction between CNT and tantalum substrate. • Strong edge effect was achieved from an array of small circular emitters of CNTs. • The good quality CNT rooting and the edge effect enhanced an emission current.

Band-gap sensitive adsorption of fluorine molecules on sidewalls of carbon nanotubes: an ab initio study

International Nuclear Information System (INIS)

Choi, Woon Ih; Park, Sohee; Kim, Tae-Eun; Park, Noejung; Lee, Kwang-Ryeol; Lee, Young Hee; Ihm, Jisoon; Han, Seungwu

2006-01-01

We report from ab initio calculations that the band-gap sensitive side-wall functionalization of a carbon nanotube is feasible with the fluorine molecule (F 2 ), which can provide a route to the extraction of semiconducting nanotubes by etching away metallic ones. In the small diameter cases like (11, 0) and (12, 0), the nanotubes are easily functionalized with F 2 regardless of their electronic properties. As the diameter becomes larger, however, the fluorination is favoured on metallic CNTs with smaller activation barriers than those of semiconducting ones. Our results suggest that low-temperature exposure to F 2 molecules in the gas phase can make a dominant portion of fluorinated metallic nanotubes and unfluorinated semiconducting ones. This is consistent with recent experimental reports

Alignment of muscle precursor cells on the vertical edges of thick carbon nanotube films

Energy Technology Data Exchange (ETDEWEB)

Holt, Ian, E-mail: ian.holt@rjah.nhs.uk [Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG (United Kingdom); Institute for Science and Technology in Medicine, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Gestmann, Ingo, E-mail: Ingo.Gestmann@fei.com [FEI Europe B.V., Achtseweg Noord 5, 5651 Eindhoven (Netherlands); Wright, Andrew C., E-mail: a.wright@glyndwr.ac.uk [Advanced Materials Research Laboratory, Glyndwr University, Plas Coch, Mold Rd, Wrexham LL11 2AW (United Kingdom)

2013-10-15

The development of scaffolds and templates is an essential aspect of tissue engineering. We show that thick (> 0.5 mm) vertically aligned carbon nanotube films, made by chemical vapour deposition, can be used as biocompatible substrates for the directional alignment of mouse muscle cells where the cells grow on the exposed sides of the films. Ultra high resolution scanning electron microscopy reveals that the films themselves consist mostly of small diameter (10 nm) multi-wall carbon nanotubes of wavy morphology with some single wall carbon nanotubes. Our findings show that for this alignment to occur the nanotubes must be in pristine condition. Mechanical wiping of the films to create directional alignment is detrimental to directional bioactivity. Larger areas for study have been formed from a composite of multiply stacked narrow strips of nanotubes wipe-transferred onto elastomer supports. These composite substrates appear to show a useful degree of alignment of the cells. Highlights: • Highly oriented muscle precursor cells grown on edges of carbon nanotube pads • Mechanical treatment of nanotube pads highly deleterious to cell growth on edges • Larger areas created from wipe-transfer of narrow strips of nanotubes onto elastomer supports • Very high resolution SEM reveals clues to aligned cell growth.

Alignment of muscle precursor cells on the vertical edges of thick carbon nanotube films

International Nuclear Information System (INIS)

Holt, Ian; Gestmann, Ingo; Wright, Andrew C.

2013-01-01

The development of scaffolds and templates is an essential aspect of tissue engineering. We show that thick (> 0.5 mm) vertically aligned carbon nanotube films, made by chemical vapour deposition, can be used as biocompatible substrates for the directional alignment of mouse muscle cells where the cells grow on the exposed sides of the films. Ultra high resolution scanning electron microscopy reveals that the films themselves consist mostly of small diameter (10 nm) multi-wall carbon nanotubes of wavy morphology with some single wall carbon nanotubes. Our findings show that for this alignment to occur the nanotubes must be in pristine condition. Mechanical wiping of the films to create directional alignment is detrimental to directional bioactivity. Larger areas for study have been formed from a composite of multiply stacked narrow strips of nanotubes wipe-transferred onto elastomer supports. These composite substrates appear to show a useful degree of alignment of the cells. Highlights: • Highly oriented muscle precursor cells grown on edges of carbon nanotube pads • Mechanical treatment of nanotube pads highly deleterious to cell growth on edges • Larger areas created from wipe-transfer of narrow strips of nanotubes onto elastomer supports • Very high resolution SEM reveals clues to aligned cell growth

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.

A Computational Experiment on Single-Walled Carbon Nanotubes

Science.gov (United States)

Simpson, Scott; Lonie, David C.; Chen, Jiechen; Zurek, Eva

2013-01-01

A computational experiment that investigates single-walled carbon nanotubes (SWNTs) has been developed and employed in an upper-level undergraduate physical chemistry laboratory course. Computations were carried out to determine the electronic structure, radial breathing modes, and the influence of the nanotube's diameter on the…

A thermodynamic model for growth mechanisms of multiwall carbon nanotubes.

Energy Technology Data Exchange (ETDEWEB)

Kaatz, Forrest H.; Overmyer, Donald L.; Siegal, Michael P.

2006-02-01

Multiwall carbon nanotubes are grown via thermal chemical vapor deposition between temperatures of 630 and 830 C using acetylene in nitrogen as the carbon source. This process is modeled using classical thermodynamics to explain the total carbon deposition as a function of time and temperature. An activation energy of 1.60 eV is inferred for nanotube growth after considering the carbon solubility term. Scanning electron microscopy shows growth with diameters increasing linearly with time. Transmission electron microscopy and Raman spectroscopy show multiwall nanotubes surrounded by a glassy-carbon sheath, which grows with increasing wall thickness as growth temperatures and times rise.

Optical Characterization and Applications of Single Walled Carbon Nanotubes

Science.gov (United States)

Strano, Michael S.

2005-03-01

Recent advances in the dispersion and separation of single walled carbon nanotubes have led to new methods of optical characterization and some novel applications. We find that Raman spectroscopy can be used to probe the aggregation state of single-walled carbon nanotubes in solution or as solids with a range of varying morphologies. Carbon nanotubes experience an orthogonal electronic dispersion when in electrical contact that broadens (from 40 meV to roughly 80 meV) and shifts the interband transition to lower energy (by 60 meV). We show that the magnitude of this shift is dependent on the extent of bundle organization and the inter-nanotube contact area. In the Raman spectrum, aggregation shifts the effective excitation profile and causes peaks to increase or decrease, depending on where the transition lies, relative to the excitation wavelength. The findings are particularly relevant for evaluating nanotube separation processes, where relative peak changes in the Raman spectrum can be confused for selective enrichment. We have also used gel electrophoresis and column chromatography conducted on individually dispersed, ultrasonicated single-walled carbon nanotubes to yield simultaneous separation by tube length and diameter. Electroelution after electrophoresis is shown to produce highly resolved fractions of nanotubes with average lengths between 92 and 435 nm. Separation by diameter is concomitant with length fractionation, and nanotubes that have been cut shortest also possess the greatest relative enrichments of large-diameter species. The relative quantum yield decreases nonlinearly as the nanotube length becomes shorter. These findings enable new applications of nanotubes as sensors and biomarkers. Particularly, molecular detection using near infrared (n-IR) light between 0.9 and 1.3 eV has important biomedical applications because of greater tissue penetration and reduced auto-fluorescent background in thick tissue or whole blood media. Carbon nanotubes

Control of carbon nanotube growth using cobalt nanoparticles as catalyst

International Nuclear Information System (INIS)

Huh, Yoon; Green, Malcolm L.H.; Kim, Young Heon; Lee, Jeong Yong; Lee, Cheol Jin

2005-01-01

We have controllably grown carbon nanotubes using uniformly distributed cobalt nanoparticles as catalyst. Cobalt nanoparticles with a uniform size were synthesized by chemical reaction and colloidal solutions including the cobalt nanoparticles were prepared. The cobalt nanoparticles were uniformly distributed on silicon substrates by a spin-coating method. Carbon nanotubes with a uniform diameter were synthesized on the cobalt nanoparticles by thermal chemical vapor deposition of acetylene gas. The density and vertical alignment of carbon nanotubes could be controlled by adjusting the density of cobalt (Co) nanoparticles

Carbon nanotubes-based chemiresistive immunosensor for small molecules: detection of nitroaromatic explosives.

Science.gov (United States)

Park, Miso; Cella, Lakshmi N; Chen, Wilfred; Myung, Nosang V; Mulchandani, Ashok

2010-12-15

In recent years, there has been a growing focus on use of one-dimensional (1-D) nanostructures, such as carbon nanotubes and nanowires, as transducer elements for label-free chemiresistive/field-effect transistor biosensors as they provide label-free and high sensitivity detection. While research to-date has elucidated the power of carbon nanotubes- and other 1-D nanostructure-based field effect transistors immunosensors for large charged macromolecules such as proteins and viruses, their application to small uncharged or charged molecules has not been demonstrated. In this paper we report a single-walled carbon nanotubes (SWNTs)-based chemiresistive immunosensor for label-free, rapid, sensitive and selective detection of 2,4,6-trinitrotoluene (TNT), a small molecule. The newly developed immunosensor employed a displacement mode/format in which SWNTs network forming conduction channel of the sensor was first modified with trinitrophenyl (TNP), an analog of TNT, and then ligated with the anti-TNP single chain antibody. Upon exposure to TNT or its derivatives the bound antibodies were displaced producing a large change, several folds higher than the noise, in the resistance/conductance of SWNTs giving excellent limit of detection, sensitivity and selectivity. The sensor detected between 0.5 ppb and 5000 ppb TNT with good selectivity to other nitroaromatic explosives and demonstrated good accuracy for monitoring TNT in untreated environmental water matrix. We believe this new displacement format can be easily generalized to other one-dimensional nanostructure-based chemiresistive immuno/affinity-sensors for detecting small and/or uncharged molecules of interest in environmental monitoring and health care. Copyright © 2010 Elsevier B.V. All rights reserved.

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.

Carbon nanotube network-silicon oxide non-volatile switches.

Science.gov (United States)

Liao, Albert D; Araujo, Paulo T; Xu, Runjie; Dresselhaus, Mildred S

2014-12-08

The integration of carbon nanotubes with silicon is important for their incorporation into next-generation nano-electronics. Here we demonstrate a non-volatile switch that utilizes carbon nanotube networks to electrically contact a conductive nanocrystal silicon filament in silicon dioxide. We form this device by biasing a nanotube network until it physically breaks in vacuum, creating the conductive silicon filament connected across a small nano-gap. From Raman spectroscopy, we observe coalescence of nanotubes during breakdown, which stabilizes the system to form very small gaps in the network~15 nm. We report that carbon nanotubes themselves are involved in switching the device to a high resistive state. Calculations reveal that this switching event occurs at ~600 °C, the temperature associated with the oxidation of nanotubes. Therefore, we propose that, in switching to a resistive state, the nanotube oxidizes by extracting oxygen from the substrate.

Role of adsorbed surfactant in the reaction of aryl diazonium salts with single-walled carbon nanotubes.

Science.gov (United States)

Hilmer, Andrew J; McNicholas, Thomas P; Lin, Shangchao; Zhang, Jingqing; Wang, Qing Hua; Mendenhall, Jonathan D; Song, Changsik; Heller, Daniel A; Barone, Paul W; Blankschtein, Daniel; Strano, Michael S

2012-01-17

Because covalent chemistry can diminish the optical and electronic properties of single-walled carbon nanotubes (SWCNTs), there is significant interest in developing methods of controllably functionalizing the nanotube sidewall. To date, most attempts at obtaining such control have focused on reaction stoichiometry or strength of oxidative treatment. Here, we examine the role of surfactants in the chemical modification of single-walled carbon nanotubes with aryl diazonium salts. The adsorbed surfactant layer is shown to affect the diazonium derivatization of carbon nanotubes in several ways, including electrostatic attraction or repulsion, steric exclusion, and direct chemical modification of the diazonium reactant. Electrostatic effects are most pronounced in the cases of anionic sodium dodecyl sulfate and cationic cetyltrimethylammonium bromide, where differences in surfactant charge can significantly affect the ability of the diazonium ion to access the SWCNT surface. For bile salt surfactants, with the exception of sodium cholate, we find that the surfactant wraps tightly enough such that exclusion effects are dominant. Here, sodium taurocholate exhibits almost no reactivity under the explored reaction conditions, while for sodium deoxycholate and sodium taurodeoxycholate, we show that the greatest extent of reaction is observed among a small population of nanotube species, with diameters between 0.88 and 0.92 nm. The anomalous reaction of nanotubes in this diameter range seems to imply that the surfactant is less effective at coating these species, resulting in a reduced surface coverage on the nanotube. Contrary to the other bile salts studied, sodium cholate enables high selectivity toward metallic species and small band gap semiconductors, which is attributed to surfactant-diazonium coupling to form highly reactive diazoesters. Further, it is found that the rigidity of anionic surfactants can significantly influence the ability of the surfactant layer to

Functional materials based on carbon nanotubes: Carbon nanotube actuators and noncovalent carbon nanotube modification

Science.gov (United States)

Fifield, Leonard S.

Carbon nanotubes have attractive inherent properties that encourage the development of new functional materials and devices based on them. The use of single wall carbon nanotubes as electromechanical actuators takes advantage of the high mechanical strength, surface area and electrical conductivity intrinsic to these molecules. The work presented here investigates the mechanisms that have been discovered for actuation of carbon nanotube paper: electrostatic, quantum chemical charge injection, pneumatic and viscoelastic. A home-built apparatus for the measurement of actuation strain is developed and utilized in the investigation. An optical fiber switch, the first demonstrated macro-scale device based on the actuation of carbon nanotubes, is described and its performance evaluated. Also presented here is a new general process designed to modify the surface of carbon nanotubes in a non-covalent, non-destructive way. This method can be used to impart new functionalities to carbon nanotube samples for a variety of applications including sensing, solar energy conversion and chemical separation. The process described involves the achievement of large degrees of graphitic surface coverage with polycyclic aromatic hydrocarbons through the use of supercritical fluids. These molecules are bifunctional agents that anchor a desired chemical group to the aromatic surface of the carbon nanotubes without adversely disrupting the conjugated backbone that gives rise the attractive electronic and physical properties of the nanotubes. Both the nanotube functionalization work and the actuator work presented here emphasize how an understanding and control of nanoscale structure and phenomena can be of vital importance in achieving desired performance for active materials. Opportunities for new devices with improved function over current state-of-the-art can be envisioned and anticipated based on this understanding and control.

Synthesis of Stacked-Cup Carbon Nanotubes in a Metal Free Low Temperature System

Science.gov (United States)

Kimura, Yuki; Nuth, Joseph A.; Johnson, Natasha M.; Farmer, Kevin D.; Roberts, Kenneth P.; Hussaini, Syed R.

2011-01-01

Stacked-cup carbon nanotubes were formed by either Fischer-Tropsch type or Haber Bosch type reactions in a metal free system. Graphite particles were used as the catalyst. The samples were heated at 600 C in a gas mixture of CO 75 Torr, N2 75 Torr and H2 550 Torr for three days. Trans mission electron microscope analysis of the catalyst surface at the completion of the experiment recognized the growth of nanotubes. They were 10-50 nm in diameter and approximately 1 micrometer in length. They had a hollow channel of 5-20 nm in the center. The nanotubes may have grown on graphite surfaces by the CO disproportionation reaction and the surface tension of the carbon nucleus may have determined the diameter. Although, generally, the diameter of a carbon nanotube depends on the size of the cataly1ic particles, the diameter of the nanotubes on graphite particles was independent of the particle size and significantly confined within a narrow range compared with that produced using catalytic amorphous iron-silicate nanoparticles. Therefore, they must have an unknown formation process that is different than the generally accepted mechanism.

Diameter control of vertically aligned carbon nanotubes using CoFe2O4 nanoparticle Langmuir-Blodgett films

Science.gov (United States)

Tamiya, Shuhei; Sato, Taiga; Kushida, Masahito

2018-03-01

Vertically aligned carbon nanotubes (VA-CNTs) are suggested for utilization as a new catalyst support of polymer electrolyte fuel cells (PEFCs). The independent control of the diameter and number density of VA-CNTs is essential for application in PEFCs. As the catalyst for VA-CNT growth, we fabricated CoFe2O4 nanoparticle (NP) films using the Langmuir-Blodgett (LB) technique. Using the LB technique, we were able to separately control the diameter and number density of VA-CNTs. The number density of VA-CNTs was changed by mixing with the filler moleculer, palmitic acid (C16). The VA-CNT diameter was changed by the adjusting the CoFe2O4 NP diameter. However, the heat-induced aggregation of CoFe2O4 NPs occurred in thermal chemical vapor deposition to synthesize VA-CNTs. Therefore, we examined how to minimize the effect of heat-induced aggregation of CoFe2O4 NPs. As a result, selection of the appropriate number density and diameter of CoFe2O4 NPs was found to be important for the control of VA-CNT diameter.

EB treatment of carbon nanotube-reinforced polymer composites

International Nuclear Information System (INIS)

Szebényi, G.; Romhány, G.; Vajna, B.; Czvikovszky, T.

2012-01-01

A small amount — less than 0.5% — carbon nanotube reinforcement may improve the mechanical properties of epoxy based composite materials significantly. The basic technical problem on one side is the dispersion of the nanotubes into the viscous matrix resin, namely, the fine powder-like — less than 100 nanometer diameter — nanotubes are prone to form aggregates. On the other side, the good connection between the nanofiber and matrix, which is determining the success of the reinforcement, requires some efficient adhesion promoting treatment. The goal of our research was to give one such treatment capable of industrial size application. A two step curing epoxy/vinylester resin process technology has been developed where the epoxy component has been cured conventionally, while the vinylester has been cured by electron treatment afterwards. The sufficient irradiation dose has been selected according to Raman spectroscopy characterization. Using the developed hybrid resin system hybrid composites containing carbon fibers and multiwalled carbon nanotubes have been prepared. The effect of the electron beam induced curing of the vinylester resin on the mechanical properties of the composites has been characterized by three point bending and interlaminar shear tests, which showed clearly the superiority of the developed resin system. The results of the mechanical tests have been supported by AFM studies of the samples, which showed that the difference in the viscoelastic properties of the matrix constituents decreased significantly by the electron beam treatment.

Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons

Science.gov (United States)

Brooks, A. J.; Lim, Hyung-nam; Kilduff, James E.

2012-07-01

Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons

International Nuclear Information System (INIS)

Brooks, A J; Kilduff, James E; Lim, Hyung-nam

2012-01-01

Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7–8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π–π electron donor–acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion

How fast does water flow in carbon nanotubes?

DEFF Research Database (Denmark)

Kannam, Sridhar; Todd, Billy; Hansen, Jesper Schmidt

2013-01-01

The purpose of this paper is threefold. First, we review the existing literature on flow rates of water in carbon nanotubes. Data for the slip length which characterizes the flow rate are scattered over 5 orders of magnitude for nanotubes of diameter 0.81–10 nm. Second, we precisely compute...... the slip length using equilibrium molecular dynamics (EMD) simulations, from which the interfacial friction between water and carbon nanotubes can be found, and also via external field driven non-equilibrium molecular dynamics simulations (NEMD). We discuss some of the issues in simulation studies which...... and reliably extrapolate the results for the slip length to values of the field corresponding to experimentally accessible pressure gradients. Finally, we comment on several issues concerning water flow rates in carbon nanotubes which may lead to some future research directions in this area....

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.

Tuning the Slide-Roll Motion Mode of Carbon Nanotubes via Hydroxyl Groups

Science.gov (United States)

Li, Rui; Wang, Shiwei; Peng, Qing

2018-05-01

Controlling the motion of carbon nanotubes is critical in manipulating nanodevices, including nanorobots. Herein, we investigate the motion behavior of SWCNT (10,10) on Si substrate utilizing molecular dynamics simulations. We show that hydroxyl groups have sensitive effect on the carbon nanotube's motion mode. When the hydroxyl groups' ratio on carbon nanotube and silicon substrate surfaces is larger than 10 and 20%, respectively, the motion of carbon nanotube transforms from sliding to rolling. When the hydroxyl groups' ratio is smaller, the slide or roll mode can be controlled by the speed of carbon nanotube, which is ultimately determined by the competition between the interface potential energy and kinetic energy. The change of motion mode holds true for different carbon nanotubes with hydroxyl groups. The chirality has little effect on the motion behavior, as opposed to the diameter, attributed to the hydroxyl groups' ratio. Our study suggests a new route to control the motion behavior of carbon nanotube via hydroxyl groups.

Influence of carbon nanotubes on the buckling of microtubule bundles in viscoelastic cytoplasm using nonlocal strain gradient theory

Directory of Open Access Journals (Sweden)

A. Farajpour

Full Text Available Carbon nanotubes are a new class of microtubule-stabilizing agents since they interact with protein microtubules in living cells, interfering with cell division and inducing apoptosis. In the present work, a modified beam model is developed to investigate the effect of carbon nanotubes on the buckling of microtubule bundles in living cell. A realistic interaction model is employed using recent experimental data on the carbon nanotube-stabilized microtubules. Small scale and surface effects are taken into account applying the nonlocal strain gradient theory and surface elasticity theory. Pasternak model is used to describe the normal and shearing effects of enclosing filament matrix on the buckling behavior of the system. An exact solution is obtained for the buckling growth rates of the mixed bundle in viscoelastic surrounding cytoplasm. The present results are compared with those reported in the open literature for single microtubules and an excellent agreement is found. Finally, the effects of different parameters such as the size, chirality, position and surface energy of carbon nanotubes on the buckling growth rates of microtubule bundles are studied. It is found that the buckling growth rate may increase or decrease by adding carbon nanotubes, depending on the diameter and chirality of carbon nanotubes. Keywords: Microtubules, Carbon nanotubes, Buckling, Size effects

Synthesis of Large Arrays of Well-Aligned Carbon Nanotubes on Glass

Energy Technology Data Exchange (ETDEWEB)

Bush, P. Siegal, M.P.; Huang, Z.P.; Provencio, P.N.; Ren, Z.F.; Wang, J.H.; Xu, J.W.

1998-11-10

Free-standing aligned carbon nanotubes have previously been grown above 7000C on mesoporous silica embedded with iron nanoparticles. Here, carbon nanotubes aligned over areas up to several square centimeters were grown on nickel-coated glass below 666oC by plasma-enhanced hot filament chemical vapor deposition. Acetylene (C2H2) gas was used as the carbon source and ammonia (NH3) gas was used as a catalyst and dilution gas. Nanotubes with controllable diameters from 20 to 400 nanometers and lengths from 0.1 to 50 micrometers were obtained. Using this method, large panels of aligned carbon nanotubes can be made under conditions that are suitable for device fabrication.

Ballistic resistance capacity of carbon nanotubes

International Nuclear Information System (INIS)

Mylvaganam, Kausala; Zhang, L C

2007-01-01

Carbon nanotubes have high strength, light weight and excellent energy absorption capacity and therefore have great potential applications in making antiballistic materials. By examining the ballistic impact and bouncing-back processes on carbon nanotubes, this investigation shows that nanotubes with large radii withstand higher bullet speeds and the ballistic resistance is the highest when the bullet hits the centre of the CNT; the ballistic resistance of CNTs will remain the same on subsequent bullet strikes if the impact is after a small time interval

Search for muonium states in BN, WS[sub 2] and carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Ansaldo, E J [TRIUMF, Vancouver (Canada) Univ. of Saskatchewan, Saskatoon (Canada)

1994-07-01

A sizable missing fraction was found for semiconductors (cubic) BN and (hexagonal) WS[sub 2]. A repolarization measurement at room temperature yielded a high hyperfine frequency for the dominant muonium signal in BN. The missing fraction in carbon nanotubes with average 20 nm outer diameter was less than 4% at temperatures above 5 K, with very small relaxation in transverse and longitudinal fields, indicating that such tubulenes are microscopically (semi-)metals or small-gap semiconductors, non-magnetic and non-superconducting. (orig.)

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.

Fast synthesis of multilayer carbon nanotubes from camphor oil as an energy storage material.

Science.gov (United States)

TermehYousefi, Amin; Bagheri, Samira; Shinji, Kawasaki; Rouhi, Jalal; Rusop Mahmood, Mohamad; Ikeda, Shoichiro

2014-01-01

Among the wide range of renewable energy sources, the ever-increasing demand for electricity storage represents an emerging challenge. Utilizing carbon nanotubes (CNTs) for energy storage is closely being scrutinized due to the promising performance on top of their extraordinary features. In this work, well-aligned multilayer carbon nanotubes were successfully synthesized on a porous silicon (PSi) substrate in a fast process using renewable natural essential oil via chemical vapor deposition (CVD). Considering the influx of vaporized multilayer vertical carbon nanotubes (MVCNTs) to the PSi, the diameter distribution increased as the flow rate decreased in the reactor. Raman spectroscopy results indicated that the crystalline quality of the carbon nanotubes structure exhibits no major variation despite changes in the flow rate. Fourier transform infrared (FT-IR) spectra confirmed the hexagonal structure of the carbon nanotubes because of the presence of a peak corresponding to the carbon double bond. Field emission scanning electron microscopy (FESEM) images showed multilayer nanotubes, each with different diameters with long and straight multiwall tubes. Moreover, the temperature programmed desorption (TPD) method has been used to analyze the hydrogen storage properties of MVCNTs, which indicates that hydrogen adsorption sites exist on the synthesized multilayer CNTs.

Fast Synthesis of Multilayer Carbon Nanotubes from Camphor Oil as an Energy Storage Material

Science.gov (United States)

TermehYousefi, Amin; Bagheri, Samira; Shinji, Kawasaki; Rouhi, Jalal; Rusop Mahmood, Mohamad; Ikeda, Shoichiro

2014-01-01

Among the wide range of renewable energy sources, the ever-increasing demand for electricity storage represents an emerging challenge. Utilizing carbon nanotubes (CNTs) for energy storage is closely being scrutinized due to the promising performance on top of their extraordinary features. In this work, well-aligned multilayer carbon nanotubes were successfully synthesized on a porous silicon (PSi) substrate in a fast process using renewable natural essential oil via chemical vapor deposition (CVD). Considering the influx of vaporized multilayer vertical carbon nanotubes (MVCNTs) to the PSi, the diameter distribution increased as the flow rate decreased in the reactor. Raman spectroscopy results indicated that the crystalline quality of the carbon nanotubes structure exhibits no major variation despite changes in the flow rate. Fourier transform infrared (FT-IR) spectra confirmed the hexagonal structure of the carbon nanotubes because of the presence of a peak corresponding to the carbon double bond. Field emission scanning electron microscopy (FESEM) images showed multilayer nanotubes, each with different diameters with long and straight multiwall tubes. Moreover, the temperature programmed desorption (TPD) method has been used to analyze the hydrogen storage properties of MVCNTs, which indicates that hydrogen adsorption sites exist on the synthesized multilayer CNTs. PMID:25258714

77 FR 21734 - Certain Small Diameter Carbon and Alloy Seamless Standard, Line, and Pressure Pipe From Romania...

Science.gov (United States)

2012-04-11

... DEPARTMENT OF COMMERCE International Trade Administration [A-485-805] Certain Small Diameter Carbon and Alloy Seamless Standard, Line, and Pressure Pipe From Romania: Extension of Time Limit for... diameter carbon and alloy seamless standard, line and pressure pipe from Romania for the period August 1...

EDITORIAL: Focus on Carbon Nanotubes

Science.gov (United States)

2003-09-01

planes to stable loops caused by annealing M Endo, B J Lee, Y A Kim, Y J Kim, H Muramatsu, T Yanagisawa, T Hayashi, M Terrones and M S Dresselhaus Energetics and electronic structure of C70-peapods and one-dimensional chains of C70 Susumu Okada, Minoru Otani and Atsushi Oshiyama Theoretical characterization of several models of nanoporous carbon F Valencia, A H Romero, E Hernández, M Terrones and H Terrones First-principles molecular dynamics study of the stretching frequencies of hydrogen molecules in carbon nanotubes Gabriel Canto, Pablo Ordejón, Cheng Hansong, Alan C Cooper and Guido P Pez The geometry and the radial breathing mode of carbon nanotubes: beyond the ideal behaviour Jeno Kürti, Viktor Zólyomi, Miklos Kertesz and Sun Guangyu Curved nanostructured materials Humberto Terrones and Mauricio Terrones A one-dimensional Ising model for C70 molecular ordering in C70-peapods Yutaka Maniwa, Hiromichi Kataura, Kazuyuki Matsuda and Yutaka Okabe Nanoengineering of carbon nanotubes for nanotools Yoshikazu Nakayama and Seiji Akita Narrow diameter double-wall carbon nanotubes: synthesis, electron microscopy and inelastic light scattering R R Bacsa, E Flahaut, Ch Laurent, A Peigney, S Aloni, P Puech and W S Bacsa Sensitivity of single multiwalled carbon nanotubes to the environment M Krüger, I Widmer, T Nussbaumer, M Buitelaar and C Schönenberger Characterizing carbon nanotube samples with resonance Raman scattering A Jorio, M A Pimenta, A G Souza Filho, R Saito, G Dresselhaus and M S Dresselhaus FTIR-luminescence mapping of dispersed single-walled carbon nanotubes Sergei Lebedkin, Katharina Arnold, Frank Hennrich, Ralph Krupke, Burkhard Renker and Manfred M Kappes Structural properties of Haeckelite nanotubes Ph Lambin and L P Biró Structural changes in single-walled carbon nanotubes under non-hydrostatic pressures: x-ray and Raman studies Sukanta Karmakar, Surinder M Sharma, P V Teredesai, D V S Muthu, A Govindaraj, S K Sikka and A K Sood Novel properties of 0

Large quantity production of carbon and boron nitride nanotubes by mechano-thermal process

International Nuclear Information System (INIS)

Chen, Y.; Fitzgerald, J.D.; Chadderton, L.; Williams, J.S.; Campbell, S.J.

2002-01-01

Full text: Nanotube materials including carbon and boron nitride have excellent properties compared with bulk materials. The seamless graphene cylinders with a high length to diameter ratio make them as superstrong fibers. A high amount of hydrogen can be stored into nanotubes as future clean fuel source. Theses applications require large quantity of nanotubes materials. However, nanotube production in large quantity, fully controlled quality and low costs remains challenges for most popular synthesis methods such as arc discharge, laser heating and catalytic chemical decomposition. Discovery of new synthesis methods is still crucial for future industrial application. The new low-temperature mechano-thermal process discovered by the current author provides an opportunity to develop a commercial method for bulk production. This mechano-thermal process consists of a mechanical ball milling and a thermal annealing processes. Using this method, both carbon and boron nitride nanotubes were produced. I will present the mechano-thermal method as the new bulk production technique in the conference. The lecture will summarise main results obtained. In the case of carbon nanotubes, different nanosized structures including multi-walled nanotubes, nanocells, and nanoparticles have been produced in a graphite sample using a mechano-thermal process, consisting of I mechanical milling at room temperature for up to 150 hours and subsequent thermal annealing at 1400 deg C. Metal particles have played an important catalytic effect on the formation of different tubular structures. While defect structure of the milled graphite appears to be responsible for the formation of small tubes. It is found that the mechanical treatment of graphite powder produces a disordered and microporous structure, which provides nucleation sites for nanotubes as well as free carbon atoms. Multiwalled carbon nanotubes appear to grow via growth of the (002) layers during thermal annealing. In the case of BN

The effect of carbon nanotube dimensions and dispersion on the fatigue behavior of epoxy nanocomposites

International Nuclear Information System (INIS)

Zhang, W; Picu, R C; Koratkar, N

2008-01-01

Fatigue is one of the primary reasons for failure in structural materials. It has been demonstrated that carbon nanotubes can suppress fatigue in polymer composites via crack-bridging and a frictional pull-out mechanism. However, a detailed study of the effects of nanotube dimensions and dispersion on the fatigue behavior of nanocomposites has not been performed. In this work, we show the strong effect of carbon nanotube dimensions (i.e. length, diameter) and dispersion quality on fatigue crack growth suppression in epoxy nanocomposites. We observe that the fatigue crack growth rates can be significantly reduced by (1) reducing the nanotube diameter, (2) increasing the nanotube length and (3) improving the nanotube dispersion. We qualitatively explain these observations by using a fracture mechanics model based on crack-bridging and pull-out of the nanotubes. By optimizing the above parameters (tube length, diameter and dispersion) we demonstrate an over 20-fold reduction in the fatigue crack propagation rate for the nanocomposite epoxy compared to the baseline (unfilled) epoxy

Carbon nanotube forests growth using catalysts from atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Chen, Bingan; Zhang, Can; Esconjauregui, Santiago; Xie, Rongsi; Zhong, Guofang; Robertson, John [Department of Engineering, University of Cambridge, Cambridge CB3 0FA (United Kingdom); Bhardwaj, Sunil [Istituto Officina dei Materiali-CNR Laboratorio TASC, s.s. 14, km 163.4, I-34012 Trieste (Italy); Sincrotone Trieste S.C.p.A., s.s. 14, km 163.4, I-34149 Trieste (Italy); Cepek, Cinzia [Istituto Officina dei Materiali-CNR Laboratorio TASC, s.s. 14, km 163.4, I-34012 Trieste (Italy)

2014-04-14

We have grown carbon nanotubes using Fe and Ni catalyst films deposited by atomic layer deposition. Both metals lead to catalytically active nanoparticles for growing vertically aligned nanotube forests or carbon fibres, depending on the growth conditions and whether the substrate is alumina or silica. The resulting nanotubes have narrow diameter and wall number distributions that are as narrow as those grown from sputtered catalysts. The state of the catalyst is studied by in-situ and ex-situ X-ray photoemission spectroscopy. We demonstrate multi-directional nanotube growth on a porous alumina foam coated with Fe prepared by atomic layer deposition. This deposition technique can be useful for nanotube applications in microelectronics, filter technology, and energy storage.

Carbon nanotubes shynthesis in fluidized bed reactor equipped with a cyclone

Science.gov (United States)

Setyopratomo, P.; Sudibandriyo, M.; Wulan, P. P. D. K.

2018-03-01

This work aimed to observe the performance of a fluidized bed reactor which was equipped with a cyclone in the synthesis of carbon nanotubes (CNT) by chemical vapor deposition. Liquefied petroleum gas with a constant volumetric flow rate of 1940 cm3/minutes was fed to the reactor as a carbon source, while a combination of metal components of Fe-Co-Mo supported on MgO was used as catalyst. The CNT synthesis was carried out at a reaction temperature which was maintained at around 800 – 850 °C for 1 hour. The CNT yield was decreased sharply when the catalyst feed was increased. The carbon efficiency is directly proportional to the mass of catalyst fed. It was found from the experiment that the mass of as-grown CNT increased in proportion to the increase of the catalyst mass fed. A sharp increase of the mass percentage of carbon nanotubes entrainment happened when the catalyst feed was raised from 3 to 7 grams. Agglomerates of carbon nanotubes have been formed. The agglomerates composed of mutually entangled carbon nanotubes which have an outer diameter range 8 – 14 nm and an inner diameter range 4 – 10 nm, which confirmed that the multi-walled carbon nanotubes were formed in this synthesis. It was found that the mesopores dominate the pore structure of the CNT product and contribute more than 90 % of the total pore volume.

A one-step single source route to carbon nanotubes

Indian Academy of Sciences (India)

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 ...

Optical absorption and thermal transport of individual suspended carbon nanotube bundles.

Science.gov (United States)

Hsu, I-Kai; Pettes, Michael T; Bushmaker, Adam; Aykol, Mehmet; Shi, Li; Cronin, Stephen B

2009-02-01

A focused laser beam is used to heat individual single-walled carbon nanotube bundles bridging two suspended microthermometers. By measurement of the temperature rise of the two thermometers, the optical absorption of 7.4-10.3 nm diameter bundles is found to be between 0.03 and 0.44% of the incident photons in the 0.4 microm diameter laser spot. The thermal conductance of the bundle is obtained with the additional measurement of the temperature rise of the nanotubes in the laser spot from shifts in the Raman G band frequency. According to the nanotube bundle diameter determined by transmission electron microscopy, the thermal conductivity is obtained.

Influence of Fe nanoparticles diameters on the structure and electron emission studies of carbon nanotubes and multilayer graphene

International Nuclear Information System (INIS)

Sharma, Himani; Shukla, A.K.; Vankar, V.D.

2013-01-01

In this paper we report the effect of Fe film thickness on the growth, structure and electron emission characteristics of carbon nanotubes (CNTs) and multilayer graphene deposited on Si substrate. It is observed that the number of graphitic shells in carbon nanostructures (CNs) varies with the thickness of the catalyst depending on the average size of nanoparticles. Further, the Fe nanoparticles do not catalyze beyond a particular size of nanoclusters leading to the formation of multilayer graphene structure, instead of carbon nanotubes (CNTs). It is observed that the crystallinity of CNs enhances upon increasing the catalyst thickness. Multilayer graphene structures show improved crystallinity in comparison to CNTs as graphitic to defect mode intensity ratio (I D /I G ) decreases from 1.2 to 0.8. However, I 2D /I G value for multilayer graphene is found to be 1.1 confirming the presence of at least 10 layers of graphene in these samples. CNTs with smaller diameter show better electron emission properties with enhancement factor (γ C = 2.8 × 10 3 ) in comparison to multilayer graphene structure (γ C = 1.5 × 10 3 ). The better emission characteristics in CNTs are explained due to combination of electrons from edges as well as centers in comparison to the multilayer graphene. Highlights: ► Graphitic shells in CNTs and graphene depend on the size of Fe nanoparticles. ► The diameter of nanoparticles decides the morphology of CNTs and graphene. ► Multilayer graphene structures show improved crystallinity in comparison to CNTs. ► Multilayer graphene (MLG) has the γ C factor of 1.5 × 10 3 and CNTs has 2.8 × 10 3 . ► The nonlinearity in MLG may occur through change in work function.

Fracture of vacancy-defected carbon nanotubes and their embedded nanocomposites

International Nuclear Information System (INIS)

Xiao Shaoping; Hou Wenyi

2006-01-01

In this paper, we investigate effects of vacancy defects on fracture of carbon nanotubes and carbon nanotube/aluminum composites. Our studies show that even a one-atom vacancy defect can dramatically reduce the failure stresses and strains of carbon nanotubes. Consequently, nanocomposites, in which vacancy-defected nanotubes are embedded, exhibit different characteristics from those in which pristine nanotubes are embedded. It has been found that defected nanotubes with a small volume fraction cannot reinforce but instead weaken nanocomposite materials. Although a large volume fraction of defected nanotubes can slightly increase the failure stresses of nanocomposites, the failure strains of nanocomposites are always decreased

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.

Gas sensing with gold-decorated vertically aligned carbon nanotubes.

Science.gov (United States)

Mudimela, Prasantha R; Scardamaglia, Mattia; González-León, Oriol; Reckinger, Nicolas; Snyders, Rony; Llobet, Eduard; Bittencourt, Carla; Colomer, Jean-François

2014-01-01

Vertically aligned carbon nanotubes of different lengths (150, 300, 500 µm) synthesized by thermal chemical vapor deposition and decorated with gold nanoparticles were investigated as gas sensitive materials for detecting nitrogen dioxide (NO2) at room temperature. Gold nanoparticles of about 6 nm in diameter were sputtered on the top surface of the carbon nanotube forests to enhance the sensitivity to the pollutant gas. We showed that the sensing response to nitrogen dioxide depends on the nanotube length. The optimum was found to be 300 µm for getting the higher response. When the background humidity level was changed from dry to 50% relative humidity, an increase in the response to NO2 was observed for all the sensors, regardless of the nanotube length.

Gas sensing with gold-decorated vertically aligned carbon nanotubes

Directory of Open Access Journals (Sweden)

Prasantha R. Mudimela

2014-06-01

Full Text Available Vertically aligned carbon nanotubes of different lengths (150, 300, 500 µm synthesized by thermal chemical vapor deposition and decorated with gold nanoparticles were investigated as gas sensitive materials for detecting nitrogen dioxide (NO2 at room temperature. Gold nanoparticles of about 6 nm in diameter were sputtered on the top surface of the carbon nanotube forests to enhance the sensitivity to the pollutant gas. We showed that the sensing response to nitrogen dioxide depends on the nanotube length. The optimum was found to be 300 µm for getting the higher response. When the background humidity level was changed from dry to 50% relative humidity, an increase in the response to NO2 was observed for all the sensors, regardless of the nanotube length.

Fast Synthesis of Multilayer Carbon Nanotubes from Camphor Oil as an Energy Storage Material

Directory of Open Access Journals (Sweden)

Amin TermehYousefi

2014-01-01

Full Text Available Among the wide range of renewable energy sources, the ever-increasing demand for electricity storage represents an emerging challenge. Utilizing carbon nanotubes (CNTs for energy storage is closely being scrutinized due to the promising performance on top of their extraordinary features. In this work, well-aligned multilayer carbon nanotubes were successfully synthesized on a porous silicon (PSi substrate in a fast process using renewable natural essential oil via chemical vapor deposition (CVD. Considering the influx of vaporized multilayer vertical carbon nanotubes (MVCNTs to the PSi, the diameter distribution increased as the flow rate decreased in the reactor. Raman spectroscopy results indicated that the crystalline quality of the carbon nanotubes structure exhibits no major variation despite changes in the flow rate. Fourier transform infrared (FT-IR spectra confirmed the hexagonal structure of the carbon nanotubes because of the presence of a peak corresponding to the carbon double bond. Field emission scanning electron microscopy (FESEM images showed multilayer nanotubes, each with different diameters with long and straight multiwall tubes. Moreover, the temperature programmed desorption (TPD method has been used to analyze the hydrogen storage properties of MVCNTs, which indicates that hydrogen adsorption sites exist on the synthesized multilayer CNTs.

Study on the growth of aligned carbon nanotubes controlled by ion bombardment

International Nuclear Information System (INIS)

Wang Biben; Zhang Bing; Zheng Kun; Hao Wei; Wang Wanlu; Liao Kejun

2004-01-01

Aligned carbon nanotubes were prepared by plasma-enhanced hot filament chemical vapor deposition using CH 4 , H 2 and NH 3 as reaction gases. It was investigated how different negative bias affects the growth of aligned carbon nanotubes. The results indicate that the average diameter of the aligned carbon nanotubes is reduced and the average length of the aligned carbon nanotubes is increased with increasing negative bias. Because of the occurrence of glow discharge, a cathode sheath forms near the substrate surface, and a number of ions are produced in it, and a very strong electrical field builds up near the substrate surface. Under the effect of the field, the strong bombardment of ions on the substrate surface will influence the growth of aligned carbon nanotubes. Combined with related theories, authors have analyzed and discussed the ion bombardment effects on the growth of the aligned carbon nanotudes

Carbon nanotube array actuators

International Nuclear Information System (INIS)

Geier, S; Mahrholz, T; Wierach, P; Sinapius, M

2013-01-01

Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750–2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs. (paper)

The Use of Multi-Walled Carbon Nanotubes as Possible Carrier in Drug Delivery System for Aspirin

Science.gov (United States)

Yusof, Alias Mohd.; Buang, Nor Aziah; Yean, Lee Sze; Ibrahim, Mohd. Lokman

2009-06-01

Carbon nanotubes (CNTs) have raised great interest in a number of applications, including field emission, energy storage, molecular electronics, sensors, biochips and drug delivery systems. This is due to their remarkable mechanical properties, chemical stability and biofunctionalizability. This nanomaterial is low in weight, has high strength and a high aspect ratio (long length compared to a small diameter). This paper will present a brief overview of drugs adsorbed onto the surface of carbon nanotubes via sonication method. The surface area of carbon nanotubes was measured by methylene blue method, Carbon nanotubes synthesized by catalytic chemical vapor deposition (CCVD) method were purified and functionalized in a mixture of concentrated acids (H2SO4:HNO3 = 3:1) at room temperature (25° C) via sonication in water bath, yielding carboxylic acid group on the CNTs' surface. CNT was successfully loaded with 48 %(w/w) aspirin molecules by suspending CNTs in a solution of aspirin in alcohol. Analysis of loaded CNTs by Field Emission-Scanning Electron Microscope (FESEM), Fourier Transform Infrared Spectrum (FITR) and UV-visible Spectroscopy confirmed the loading of the drug onto the CNTs. The work presented is a prelude to the direction of using carbon nanotubes as a drug delivery system to desired sites in human body.

Parametric study on vapor-solid-solid growth mechanism of multiwalled carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Shukrullah, S., E-mail: zshukrullah@gmail.com [Center of Innovative Nanostructures and Nanodevices, Universiti Teknologi PETRONAS, 32610, Bandar Seri Iskandar, Perak (Malaysia); Mohamed, N.M. [Center of Innovative Nanostructures and Nanodevices, Universiti Teknologi PETRONAS, 32610, Bandar Seri Iskandar, Perak (Malaysia); Shaharun, M.S. [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 32610, Bandar Seri Iskandar, Perak (Malaysia); Naz, M.Y. [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 32610, Bandar Seri Iskandar, Perak (Malaysia)

2016-06-15

This study aimed at investigating the effect of the fluidized bed chemical vapor deposition (FBCVD) process parameters on growth mechanism, morphology and purity of the multiwalled carbon nanotubes (MWCNTs). Nanotubes were produced in a vertical FBCVD reactor by catalytic decomposition of ethylene over Al{sub 2}O{sub 3} supported nano-iron catalyst buds at different flow rates. FESEM, TEM, Raman spectroscopy and TGA thermograms were used to elaborate the growth parameters of the as grown MWCNTs. As the growth process was driven by the process temperatures well below the iron-carbon eutectic temperature (1147 °C), the appearance of graphite platelets from the crystallographic faces of the catalyst particles suggested a solid form of the catalyst during CNT nucleation. A vapor-solid-solid (VSS) growth mechanism was predicted for nucleation of MWCNTs with very low activation energy. The nanotubes grown at optimized temperature and ethylene flow rate posed high graphitic symmetry, purity, narrow diameter distribution and shorter inter-layer spacing. In Raman and TGA analyses, small I{sub D}/I{sub G} ratio and residual mass revealed negligible ratios of structural defects and amorphous carbon in the product. However, several structural defects and impurity elements were spotted in the nanotubes grown under unoptimized process parameters. - Graphical abstract: Arrhenius plot of relatively pure MWCNTs grown over Al2O3 supported nano-iron buds. - Highlights: • Vapor–solid–solid growth mechanism of MWCNTs was studied in a vertical FBCVD reactor. • MWCNTs were grown over Al2O3 supported nano-iron buds at very low activation energy. • FBCVD reactor was operated at temperatures well below the iron-carbon eutectic point. • Ideally graphitized structures were obtained at a process temperature of 800 °C. • Tube diameter revealed a narrow distribution of 20–25 nm at the optimum temperature.

Parametric study on vapor-solid-solid growth mechanism of multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Shukrullah, S.; Mohamed, N.M.; Shaharun, M.S.; Naz, M.Y.

2016-01-01

This study aimed at investigating the effect of the fluidized bed chemical vapor deposition (FBCVD) process parameters on growth mechanism, morphology and purity of the multiwalled carbon nanotubes (MWCNTs). Nanotubes were produced in a vertical FBCVD reactor by catalytic decomposition of ethylene over Al_2O_3 supported nano-iron catalyst buds at different flow rates. FESEM, TEM, Raman spectroscopy and TGA thermograms were used to elaborate the growth parameters of the as grown MWCNTs. As the growth process was driven by the process temperatures well below the iron-carbon eutectic temperature (1147 °C), the appearance of graphite platelets from the crystallographic faces of the catalyst particles suggested a solid form of the catalyst during CNT nucleation. A vapor-solid-solid (VSS) growth mechanism was predicted for nucleation of MWCNTs with very low activation energy. The nanotubes grown at optimized temperature and ethylene flow rate posed high graphitic symmetry, purity, narrow diameter distribution and shorter inter-layer spacing. In Raman and TGA analyses, small I_D/I_G ratio and residual mass revealed negligible ratios of structural defects and amorphous carbon in the product. However, several structural defects and impurity elements were spotted in the nanotubes grown under unoptimized process parameters. - Graphical abstract: Arrhenius plot of relatively pure MWCNTs grown over Al2O3 supported nano-iron buds. - Highlights: • Vapor–solid–solid growth mechanism of MWCNTs was studied in a vertical FBCVD reactor. • MWCNTs were grown over Al2O3 supported nano-iron buds at very low activation energy. • FBCVD reactor was operated at temperatures well below the iron-carbon eutectic point. • Ideally graphitized structures were obtained at a process temperature of 800 °C. • Tube diameter revealed a narrow distribution of 20–25 nm at the optimum temperature.

Electrochemical Capacitors Based on Aligned Carbon Nanotubes Directly Synthesized on Tantalum Substrates

International Nuclear Information System (INIS)

Kim, Byung Woo; Chung, Hae Geun; Kim, Woong; Min, Byoung Koun; Kim, Hong Gon

2010-01-01

We demonstrate that vertically aligned carbon nanotubes can be synthesized directly on tantalum substrate via waterassisted chemical vapor deposition and evaluate their properties as electrochemical capacitors. The mean diameter of the carbon nanotubes was 7.1 ± 1.5 nm, and 70% of them had double walls. The intensity ratio of G-band to D-band in Raman spectra was as high as 5, indicating good quality of the carbon nanotubes. Owing to the alignment and low equivalent series resistance, the carbon nanotube based supercapacitors showed good rate performance. Rectangular shape of cyclic voltammogram was maintained even at the scan rate of > 1 V/s in 1 M sulfuric acid aqueous solution. Specific capacitance was well-retained (∼94%) even when the discharging current density dramatically increased up to 145 A/g. Consequently, specific power as high as 60 kW/kg was obtained from as-grown carbon nanotubes in aqueous solution. Maximum specific energy of ∼20 Wh/kg was obtained when carbon nanotubes were electrochemically oxidized and operated in organic solution. Demonstration of direct synthesis of carbon nanotubes on tantalum current collectors and their applications as supercapacitors could be an invaluable basis for fabrication of high performance carbon nanotube supercapacitors

The role of carbon solubility in Fe-C nano-clusters on the growth of small single-walled carbon nanotubes

Science.gov (United States)

Curtarolo, Stefano; Awasthy, Neha; Setyawan, Wahyu; Mora, Elena; Tokune, Toshio; Bolton, Kim; Harutyunyan, Avetik

2008-03-01

Various diameters of alumina-supported Fe catalysts are used to grow single-walled carbon nanotubes (SWCNTs) with chemical vapor decomposition. We find that the reduction of the catalyst size requires an increase of the minimum temperature necessary for the growth. We address this phenomenon in terms of solubility of C in Fe nanoclusters and, by using first principles calculations, we devise a simple model to predict the behavior of the phases competing for stability in Fe-C nanoclusters at low temperature. We show that, as a function particles size, there are three scenarios compatible with steady state-, limited- and no-growth of SWCNTs, corresponding to unaffected, reduced and no solubility of C in the particles. The result raises previously unknown concerns about the growth feasibility of small and very-long SWCNTs within the current Fe CVD technology, and suggests new strategies in the search of better catalysts. Research supported by Honda R.I. and NSF.

Characterization of carbon nanotubes grown on Fe70Pd30 film

International Nuclear Information System (INIS)

Khan, Zishan H.; Islam, S.S.; Kung, S.C.; Perng, T.P.; Khan, Samina; Tripathi, K.N.; Agarwal, Monika; Zulfequar, M.; Husain, M.

2006-01-01

Carbon nanotubes have been synthesized by a LPCVD on nanocrystalline Fe-Pd film. CNTs are grown for 30min and 1h respectively. From the SEM images, the diameter of these nanotubes varies from 40-80nm and the length is several micro-meter approximately. TEM observations suggest that the CNTs are multi-walled and the structure changes from ordinary geometry of CNTs to bamboo shaped. We have observed sharp G and D bands in the Raman spectra of these carbon nanotubes. Higher D-band is observed for the carbon nanotubes grown for longer time (1h), showing that these nanotubes contain more amorphous carbon. The field emission measurements for these CNTs are also performed. For CNTs grown for longer time (1h), a superior turn-on field of 4.88V/μm (when the current density achieves 10μA/cm 2 ) is obtained and a current density of 29.36mA/cm 2 can be generated at 9.59V/μm

Effects of tube diameter and chirality on the stability of single-walled carbon nanotubes under ion irradiation

International Nuclear Information System (INIS)

Xu Zijian; Zhang Wei; Zhu Zhiyuan; Ren Cuilan; Li Yong; Huai Ping

2009-01-01

Using molecular dynamics method, we investigated the influence of tube diameter and chirality on the stability of single-walled carbon nanotubes (CNTs) under ion irradiation. We found that in the energy range below 1 keV, the dependence of CNT stability on the tube diameter is no longer monotonic under C ion irradiation, and the thinner (5, 5) CNT may be more stable than the thicker (7, 7) CNT, while under Ar irradiation, the CNT stability increases still monotonically with the CNT diameter. This stability behavior was further verified by the calculations of the threshold ion energies to produce displacement damage in CNTs. The abnormal stability of thin CNTs is related to their resistance to the instantaneous deformation in the wall induced by ion pushing, the high self-healing capacity, as well as the different interaction properties of C and Ar ions with CNT atoms. We also found that under ion irradiation the stability of a zigzag CNT is better than that of an armchair CNT with the same diameter. This is because of the bonding structure difference between the armchair and the zigzag CNTs with respect to the orientations of graphitic networks as well as the self-healing capacity difference.

Carbon Nanotube Conditioning: Ab Initio Simulations of the Effect of Interwall Interaction, Defects And Doping on the Electronic Properties of Carbon Nanotubes

Science.gov (United States)

Castillo, Matias Soto

Using carbon nanotubes for electrical conduction applications at the macroscale has been shown to be a difficult task for some time now, mainly, due to defects and impurities present, and lack of uniform electronic properties in synthesized carbon nanotube bundles. Some researchers have suggested that growing only metallic armchair nanotubes and arranging them with an ideal contact length could lead to the ultimate electrical conductivity; however, such recipe presents too high of a cost to pay. A different route is to learn to manage the defects, impurities, and the electronic properties of carbon nanotubes present in bundles grown by current state-of-the-art reactors, so that the electrical conduction of a bundle or even wire may be enhanced. In our work, we have used first-principles density functional theory calculations to study the effect of interwall interaction, defects and doping on the electronic structure of metallic, semi-metal and semiconducting single- and double-walled carbon nanotubes in order to gain a clear picture of their properties. The electronic band gap for a range of zigzag single-walled carbon nanotubes with chiral indices (5,0) - (30,0) was obtained. Their properties were used as a stepping stone in the study of the interwall interaction in double-walled carbon nanotubes, from which it was found that the electronic band gap depends on the type of inner and outer tubes, average diameter, and interwall distance. The effect of vacancy defects was also studied for a range of single-walled carbon nanotubes. It was found that the electronic band gap is reduced for the entire range of zigzag carbon nanotubes, even at vacancy defects concentrations of less than 1%. Finally, interaction potentials obtained via first-principles calculations were generalized by developing mathematical models for the purpose of running simulations at a larger length scale using molecular dynamics of the adsorption doping of diatomic iodine. An ideal adsorption site

Characterization of bundled and individual triple-walled carbon nanotubes by resonant Raman spectroscopy.

Science.gov (United States)

Hirschmann, Thomas Ch; Araujo, Paulo T; Muramatsu, Hiroyuki; Zhang, Xu; Nielsch, Kornelius; Kim, Yoong Ahm; Dresselhaus, Mildred S

2013-03-26

The optical characterization of bundled and individual triple-walled carbon nanotubes was studied for the first time in detail by using resonant Raman spectroscopy. In our approach, the outer tube of a triple-walled carbon nanotube system protects the two inner tubes (or equivalently the inner double-walled carbon nanotube) from external environment interactions making them a partially isolated system. Following the spectral changes and line-widths of the radial breathing modes and G-band by performing laser energy dependent Raman spectroscopy, it is possible to extract important information as regards to the electronic and vibrational properties, tube diameters, wall-to-wall distances, radial breathing mode, and G-band resonance evolutions as well as high-curvature intertube interactions in isolated double- and triple-walled carbon nanotube systems.

Single-walled carbon nanotube-induced mitotic disruption⋆

OpenAIRE

Sargent, L.M.; Hubbs, A.F.; Young, S.-H.; Kashon, M.L.; Dinu, C.Z.; Salisbury, J.L.; Benkovic, S.A.; Lowry, D.T.; Murray, A.R.; Kisin, E.R.; Siegrist, K.J.; Battelli, L.; Mastovich, J.; Sturgeon, J.L.; Bunker, K.L.

2011-01-01

Carbon nanotubes were among the earliest products of nanotechnology and have many potential applications in medicine, electronics, and manufacturing. The low density, small size, and biological persistence of carbon nanotubes create challenges for exposure control and monitoring and make respiratory exposures to workers likely. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to 24, 48 and 96 μg/cm2 single-walled c...

Transverse electric field–induced deformation of armchair single-walled carbon nanotube

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Yuan Ningyi

2010-01-01

Full Text Available Abstract The deformation of armchair single-walled carbon nanotube under transverse electric field has been investigated using density functional theory. The results show that the circular cross-sections of the nanotubes are deformed to elliptic ones, in which the tube diameter along the field direction is increased, whereas the diameter perpendicular to the field direction is reduced. The electronic structures of the deformed nanotubes were also studied. The ratio of the major diameter to the minor diameter of the elliptic cross-section was used to estimate the degree of the deformation. It is found that this ratio depends on the field strength and the tube diameter. However, the field direction has little role in the deformation. (See supplementary material 1 Electronic supplementary material The online version of this article (doi:10.1007/s11671-010-9617-y contains supplementary material, which is available to authorized users. Click here for file

Irradiation of carbon nanotubes with carbon projectiles: A molecular dynamics study

Energy Technology Data Exchange (ETDEWEB)

Denton, Cristian D. [Departamento de Fisica Aplicada, Universidad de Alicante, 03080 Alicante (Spain); Heredia-Avalos, Santiago; Moreno-Marin, Juan Carlos [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, 03080 Alicante (Spain)

2013-04-15

The irradiation of carbon based nanostructures with ions and electrons has been shown to be an appropriate tool to tailor their properties. The defects induced in the nanostructures during irradiation are able to modify their mechanical and electronic properties. Here we simulate the irradiation of carbon nanotubes with carbon ions using a molecular dynamics code. We use the Tersoff potential joined smoothly to the Universal Ziegler-Biersack-Littmark potential at short distances. We study the number of defects produced after irradiation with a single carbon ion finding a saturation with its energy at {proportional_to} 3 keV. We observe, after continuum irradiation with low energy ions, the formation of bumps in the irradiated region. For larger energy ions we find that the diameter of the nanotube shrinks as shown in previous works. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Finite element modeling of single-walled carbon nanotubes with introducing a new wall thickness

International Nuclear Information System (INIS)

Jalalahmadi, B; Naghdabadi, R

2007-01-01

A three-dimensional finite element (FE) model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs) is proposed. By considering the covalent bonds as connecting elements between carbon atoms, a nanotube is simulated as a space frame-like structure. Here, the carbon atoms act as joints of the connecting elements. To create the FE models, nodes are placed at the locations of carbon atoms and the bonds between them are modeled using three-dimensional elastic beam elements. Using Morse atomic potential, the elastic moduli of beam elements are obtained via considering a linkage between molecular and continuum mechanics. Also, a new wall thickness ( bond diameter) equal to 0.1296 nm is introduced. In order to demonstrate the applicability of FE model and new wall thickness, the influence of tube wall thickness, diameter and chirality on the Young's modulus of SWCNTs is investigated. It is found that the choice of wall thickness significantly affects the calculation of Young's modulus. For the values of wall thickness used in the literature, the Young's moduli are estimated which agree very well with the corresponding theoretical results and experimental measurements. We also investigate the dependence of elastic moduli on diameter and chirality of the nanotube. The larger tube diameter, the higher Young's modulus of SWCNT. The Young's modulus of chiral SWCNTs is found to be generally larger than that of armchair and zigzag SWCNTs. The presented results demonstrate that the proposed FE model and wall thickness may provide a valuable tool for studying the mechanical behavior of carbon nanotubes and their application in nano-composites

Micro glow plasma for localized nanostructural modification of carbon nanotube forest

Energy Technology Data Exchange (ETDEWEB)

Sarwar, Mirza Saquib us; Xiao, Zhiming; Saleh, Tanveer; Nojeh, Alireza; Takahata, Kenichi [University of British Columbia, Vancouver, British Columbia V6T 1Z4 (Canada)

2016-08-22

This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ∼30% and ∼300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.

Preparation and desalination performance of multiwall carbon nanotubes

International Nuclear Information System (INIS)

Zhang Dengsong; Shi Liyi; Fang Jianhui; Dai Kai; Li Xuanke

2006-01-01

Multiwall carbon nanotubes (MWCNTs) were prepared by catalytic decomposition of methane at 680-700 deg. C, using nickel oxide-silica binary aerogels as the catalyst. The morphological structure of MWCNTs was investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The results revealed that MWCNTs had a diameter of 40-60 nm, with high quality and high length/diameter ratio, and some metal catalyst particles were encapsulated at the tip of nanotubes. Using MWCNTs as the electrodes of flow-through capacitor (FTC), desalination performance was investigated. The results showed that modification methods had great effect on desalination performance of MWCNTs. The removal amount of NaCl was generally dependent on the surface area and pore volume of MWCNTs. After modification in diluted HNO 3 solution with ultrasonic and then ball milling, the metal catalyst particles at the tip of nanotubes disappeared, the nanotube length became short, the cap at the tip of nanotubes was opened, the internal surface area could be effectively used, leading to increasing the specific surface area and pore volume for MWCNTs, and thus, the desalination performance thereof was the best of all

Multiscale Modeling with Carbon Nanotubes

Energy Technology Data Exchange (ETDEWEB)

Maiti, A

2006-02-21

Technologically important nanomaterials come in all shapes and sizes. They can range from small molecules to complex composites and mixtures. Depending upon the spatial dimensions of the system and properties under investigation computer modeling of such materials can range from equilibrium and nonequilibrium Quantum Mechanics, to force-field-based Molecular Mechanics and kinetic Monte Carlo, to Mesoscale simulation of evolving morphology, to Finite-Element computation of physical properties. This brief review illustrates some of the above modeling techniques through a number of recent applications with carbon nanotubes: nano electromechanical sensors (NEMS), chemical sensors, metal-nanotube contacts, and polymer-nanotube composites.

Guided proliferation and bone-forming functionality on highly ordered large diameter TiO2 nanotube arrays

International Nuclear Information System (INIS)

Zhang, Ruopeng; Wu, Hongliu; Ni, Jiahua; Zhao, Changli; Chen, Yifan; Zheng, Chengjunyi; Zhang, Xiaonong

2015-01-01

The significantly enhanced osteoblast adhesion, proliferation and alkaline phosphatase (ALP) activity were observed on TiO 2 nanotube surface in recent studies in which the scale of nanotube diameter was restricted under 100 nm. In this paper, a series of highly ordered TiO 2 nanotube arrays with larger diameters ranging from 150 nm to 470 nm were fabricated via high voltage anodization. The behaviors of MC3T3-E1 cells in response to the diameter-controlled TiO 2 nanotubes were investigated. A contrast between the trend of proliferation and the trend of cell elongation was observed. The highest cell elongation (nearly 10:1) and the lowest cell number were observed on the TiO 2 nanotube arrays with 150 nm diameter. While, the lowest cell elongation and highest cell number were achieved on the TiO 2 nanotube arrays with 470 nm diameter. Furthermore, the ALP activity peaked on the 150 nm diameter TiO 2 nanotube arrays and decreased dramatically with the increase of nanotube diameter. Thus a narrow range of diameter (100–200 nm) that could induce the greatest bone-forming activity is determined. It is expected that more delicate design of orthopedic implant with regional abduction of cell proliferation or bone forming could be achieved by controlling the diameter of TiO 2 nanotubes. - Highlights: • Improved anodization methods leading to more ordered large diameter TiO 2 nanotubes • Significantly enhanced ALP activity was observed on 150 nm diameter TiO 2 nanotubes. • The highest cell density was observed on 470 nm diameter TiO 2 nanotube arrays. • Similar cell response was observed on the amorphous and anatase phased nanotube surface

Removal of Chromium (III from Water by Using Modified and Nonmodified Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Muataz Ali Atieh

2010-01-01

Full Text Available This study was carried out to evaluate the environmental application of modified and nonmodified carbon nanotubes through the experiment removal of chromium trivalent (III from water. The aim was to find the optimal condition of the chromium (III removal from water under different treatment conditions of pH, adsorbent dosage, contact time and agitation speed. Multi wall carbon nanotubes (MW-CNTs were characterized by field emission scanning electron microscopy (FE-SEM and transmission electron microscopy (TEM. The diameter of the carbon nanotubes produced varied from 20–40 nm with average diameter of 24 nm and 10 micrometer in length. Adsorption isotherms were used to model the adsorption behavior and to calculate the adsorption capacity of the absorbents. The results showed that, 18% of chromium (III removal was achieved using modified carbon nanotubes (M-CNTs at pH 7, 150 rpm, and 2 hours for a dosage of 150 mg of CNTs. The removal of Cr (III is mainly attributed to the affinity of chromium (III to the physical and chemical properties of the CNTs. The adsorption isotherms plots were well fitted with experimental data.

Electronic Transport Parameter of Carbon Nanotube Metal-Semiconductor On-Tube Heterojunction

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Sukirno

2009-03-01

Full Text Available Carbon Nanotubes research is one of the top five hot research topics in physics since 2006 because of its unique properties and functionalities, which leads to wide-range applications. One of the most interesting potential applications is in term of nanoelectronic device. It has been modeled carbon nanotubes heterojunction, which was built from two different carbon nanotubes, that one is metallic and the other one is semiconducting. There are two different carbon nanotubes metal-semiconductor heterojunction. The first one is built from CNT(10,10 as metallic carbon nanotube and CNT (17,0 as semiconductor carbon nanotube. The other one is built from CNT (5,5 as metallic carbon nanotube and CNT (8,0. All of the semiconducting carbon nanotubes are assumed to be a pyridine-like N-doped. Those two heterojunctions are different in term of their structural shape and diameter. It has been calculated their charge distribution and potential profile, which would be useful for the simulation of their electronic transport properties. The calculations are performed by using self-consistent method to solve Non-Homogeneous Poisson’s Equation with aid of Universal Density of States calculation method for Carbon Nanotubes. The calculations are done by varying the doping fraction of the semiconductor carbon nanotubes The electron tunneling transmission coefficient, for low energy region, also has been calculated by using Wentzel-Kramer-Brillouin (WKB approximation. From the calculation results, it is obtained that the charge distribution as well as the potential profile of this device is doping fraction dependent. It is also inferred that the WKB method is fail to be used to calculate whole of the electron tunneling coefficient in this system. It is expected that further calculation for electron tunneling coefficient in higher energy region as well as current-voltage characteristic of this system will become an interesting issue for this carbon nanotube based

Electrodes from carbon nanotubes/NiO nanocomposites synthesized in modified Watts bath for supercapacitors

Science.gov (United States)

Hakamada, Masataka; Abe, Tatsuhiko; Mabuchi, Mamoru

2016-09-01

A modified Watts bath coupled with pulsed current electroplating is used to uniformly deposit ultrafine nickel oxide particles (diameter < 4 nm) on multiwalled carbon nanotubes. The capacitance of the multiwalled carbon nanotubes/nickel oxide electrodes was as high as 2480 F g-1 (per mass of nickel oxide), which is close to the theoretical capacitance of NiO.

Controllable synthesis of carbon nanotubes by changing the Mo content in bimetallic Fe-Mo/MgO catalyst

International Nuclear Information System (INIS)

Xu Xiangju; Huang Shaoming; Yang Zhi; Zou Chao; Jiang Junfan; Shang Zhijie

2011-01-01

Research highlights: → Increasing the Mo content in the Fe-Mo/MgO catalysts resulted in an increase in wall number, diameter and growth yield of carbon nanotubes. → The Fe interacts with MgO to form complex (MgO) x (FeO) 1-x (0 4 and relative large metal Mo particles can be generated after reduction. → The avalanche-like reduction of MgMoO 4 makes the catalyst particles to be small thus enhances the utilize efficiency of Fe nanoparticles. - Abstract: A series of Fe-Mo/MgO catalysts with different Mo content were prepared by combustion method and used as catalysts for carbon nanotube (CNT) growth. Transmission electron microscopy studies of the nanotubes show that the number of the CNT walls and the CNT diameters increase with the increasing of Mo content in the bimetallic catalyst. The growth yield determined by thermogravimetric analysis also follows the trend: the higher the Mo content, the higher the yield of the CNTs. However, the increase of Mo content leads to the lower degree of graphitization of CNTs. A comparative study on the morphology and catalytic functions of Fe/MgO, Mo/MgO and Fe-Mo/MgO catalysts was carried out by scanning electron microscopy and X-ray diffraction. It is found that the Fe interacts with MgO to form complexes and is then dispersed into the MgO support uniformly, resulting in very small Fe nanoparticles after reduction. The Mo interacts with MgO to form stoichiometry compound MgMoO 4 and relative large metal Mo particles can be generated after reduction. High yield CNTs with small diameter can be generated from Fe-Mo/MgO because the avalanche-like reduction of MgMoO 4 makes the catalyst particles to be small thus enhances the utilize efficiency of Fe nanoparticles.

Effects of nitrogen-doped multi-walled carbon nanotubes compared to pristine multi-walled carbon nanotubes on human small airway epithelial cells.

Science.gov (United States)

Mihalchik, Amy L; Ding, Weiqiang; Porter, Dale W; McLoughlin, Colleen; Schwegler-Berry, Diane; Sisler, Jennifer D; Stefaniak, Aleksandr B; Snyder-Talkington, Brandi N; Cruz-Silva, Rodolfo; Terrones, Mauricio; Tsuruoka, Shuji; Endo, Morinobu; Castranova, Vincent; Qian, Yong

2015-07-03

Nitrogen-doped multi-walled carbon nanotubes (ND-MWCNTs) are modified multi-walled carbon nanotubes (MWCNTs) with enhanced electrical properties that are used in a variety of applications, including fuel cells and sensors; however, the mode of toxic action of ND-MWCNT has yet to be fully elucidated. In the present study, we compared the interaction of ND-MWCNT or pristine MWCNT-7 with human small airway epithelial cells (SAEC) and evaluated their subsequent bioactive effects. Transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction suggested the presence of N-containing defects in the lattice of the nanotube. The ND-MWCNTs were determined to be 93.3% carbon, 3.8% oxygen, and 2.9% nitrogen. A dose-response cell proliferation assay showed that low doses of ND-MWCNT (1.2μg/ml) or MWCNT-7 (0.12μg/ml) increased cellular proliferation, while the highest dose of 120μg/ml of either material decreased proliferation. ND-MWCNT and MWCNT-7 appeared to interact with SAEC at 6h and were internalized by 24h. ROS were elevated at 6 and 24h in ND-MWCNT exposed cells, but only at 6h in MWCNT-7 exposed cells. Significant alterations to the cell cycle were observed in SAEC exposed to either 1.2μg/ml of ND-MWCNT or MWCNT-7 in a time and material-dependent manner, possibly suggesting potential damage or alterations to cell cycle machinery. Our results indicate that ND-MWCNT induce effects in SAEC over a time and dose-related manner which differ from MWCNT-7. Therefore, the physicochemical characteristics of the materials appear to alter their biological effects. Published by Elsevier Ireland Ltd.

Purification of carbon nanotubes via selective heating

Science.gov (United States)

Rogers, John A.; Wilson, William L.; Jin, Sung Hun; Dunham, Simon N.; Xie, Xu; Islam, Ahmad; Du, Frank; Huang, Yonggang; Song, Jizhou

2017-11-21

The present invention provides methods for purifying a layer of carbon nanotubes comprising providing a precursor layer of substantially aligned carbon nanotubes supported by a substrate, wherein the precursor layer comprises a mixture of first carbon nanotubes and second carbon nanotubes; selectively heating the first carbon nanotubes; and separating the first carbon nanotubes from the second carbon nanotubes, thereby generating a purified layer of carbon nanotubes. Devices benefiting from enhanced electrical properties enabled by the purified layer of carbon nanotubes are also described.

Migration of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling

Directory of Open Access Journals (Sweden)

Peng Hao

2011-01-01

Full Text Available Abstract The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 μm were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt.%, the heat flux is from 10 to 100 kW·m-2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results indicate that the migration ratio of carbon nanotube increases with the increase of the outside diameter or the length of carbon nanotube. For the fixed type of carbon nanotube, the migration ratio decreases with the increase of the oil concentration or the heat flux, and increases with the increase of the initial liquid-level height. The migration ratio of carbon nanotube increases with the decrease of dynamic viscosity of refrigerant or the increase of liquid phase density of refrigerant. A model for predicting the migration ratio of carbon nanotubes in the refrigerant-based nanofluid pool boiling is proposed, and the predictions agree with 92% of the experimental data within a deviation of ±20%.

Imaging active topological defects in carbon nanotubes

Science.gov (United States)

Suenaga, Kazu; Wakabayashi, Hideaki; Koshino, Masanori; Sato, Yuta; Urita, Koki; Iijima, Sumio

2007-06-01

A single-walled carbon nanotube (SWNT) is a wrapped single graphene layer, and its plastic deformation should require active topological defects-non-hexagonal carbon rings that can migrate along the nanotube wall. Although in situ transmission electron microscopy (TEM) has been used to examine the deformation of SWNTs, these studies deal only with diameter changes and no atomistic mechanism has been elucidated experimentally. Theory predicts that some topological defects can form through the Stone-Wales transformation in SWNTs under tension at 2,000 K, and could act as a dislocation core. We demonstrate here, by means of high-resolution (HR)-TEM with atomic sensitivity, the first direct imaging of pentagon-heptagon pair defects found in an SWNT that was heated at 2,273 K. Moreover, our in situ HR-TEM observation reveals an accumulation of topological defects near the kink of a deformed nanotube. This result suggests that dislocation motions or active topological defects are indeed responsible for the plastic deformation of SWNTs.

Recent development of carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Yamabe, Tokio [Div. of Molecular Engineering, Kyoto Univ. (Japan); [Inst. for Fundamental Chemistry, Kyoto (Japan)

1995-03-15

Recent developments of carbon nanotubes are reviewed. Analytical solutions for the electronic structure of carbon nanotube on the basis of thight-binding approximation are presented and interpreted using the concepts of crystal orbital. The electronic properties of actual carbon nanotubes are presented. The electronic structures of carbon nanotubes in the presence of magnetic fiels are also summerized. (orig.)

Quantitative Analysis of Isolated Single-Wall Carbon Nanotubes with Their Molar Absorbance Coefficients

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Shota Kuwahara

2014-01-01

Full Text Available The molar absorbance coefficients of metallic, semiconducting, and (6,5 chirality enriched single-wall carbon nanotubes were evaluated by a spray technique combined with atomic force microscopy. Single-wall carbon nanotubes with isolated and a single predominant electronic type were obtained by using the density-gradient ultracentrifugation technique. In the visible region, all coefficients had similar values around 2–5 × 109/mL mol−1 cm−1, independent of their diameter distribution and the electronic types of single-wall carbon nanotubes, and the εS22/εM11  and εS11/εM11 were estimated to be 1.0 and 4.0, respectively. The coefficient strongly depends on the length of single-wall carbon nanotubes, independent of their electronic types and chirality.

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.

Resonant ablation of single-wall carbon nanotubes by femtosecond laser pulses

International Nuclear Information System (INIS)

Arutyunyan, N R; Komlenok, M S; Kononenko, V V; Pashinin, V P; Pozharov, A S; Konov, V I; Obraztsova, E D

2015-01-01

The thin 50 nm film of bundled arc-discharge single-wall carbon nanotubes was irradiated by femtosecond laser pulses with wavelengths 675, 1350 and 1745 nm corresponding to the absorption band of metallic nanotubes E 11 M , to the background absorption and to the absorption band of semiconducting nanotubes E 11 S , respectively. The aim was to induce a selective removal of nanotubes of specific type from the bundled material. Similar to conducted thermal heating experiments, the effect of laser irradiation results in suppression of all radial breathing modes in the Raman spectra, with preferential destruction of the metallic nanotubes with diameters less than 1.26 nm and of the semiconducting nanotubes with diameters 1.36 nm. However, the etching rate of different nanotubes depends on the wavelength of the laser irradiation. It is demonstrated that the relative content of nanotubes of different chiralities can be tuned by a resonant laser ablation of undesired nanotube fraction. The preferential etching of the resonant nanotubes has been shown for laser wavelengths 675 nm (E 11 M ) and 1745 nm (E 11 S ). (paper)

Enhanced electrochemical activity using vertically aligned carbon nanotube electrodes grown on carbon fiber

Directory of Open Access Journals (Sweden)

Evandro Augusto de Morais

2011-09-01

Full Text Available Vertically aligned carbon nanotubes were successfully grown on flexible carbon fibers by plasma enhanced chemical vapor deposition. The diameter of the CNT is controllable by adjusting the thickness of the catalyst Ni layer deposited on the fiber. Vertically aligned nanotubes were grown in a Plasma Enhanced Chemical Deposition system (PECVD at a temperature of 630 ºC, d.c. bias of -600 V and 160 and 68 sccm flow of ammonia and acetylene, respectively. Using cyclic voltammetry measurements, an increase of the surface area of our electrodes, up to 50 times higher, was observed in our samples with CNT. The combination of VACNTs with flexible carbon fibers can have a significant impact on applications ranging from sensors to electrodes for fuel cells.

Synthesis of single and multi-shell carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Lambert, J M [Groupe de Dynamique des Phases Condensees, Univ. de Montpellier 2, 34 Montpellier (France); Ajayan, P M [Lab. de Physique des Solides, Univ. Paris-Sud, 91 Orsay (France); Bernier, P [Groupe de Dynamique des Phases Condensees, Univ. de Montpellier 2, 34 Montpellier (France)

1995-03-15

We report here interesting growth morphologies produced during the electric arc-discharge between a graphite cathode and different composite metal-graphite anodes: when the metal is pure cobalt powder, we obtain, under certain conditions of pressure and cobalt content in the electrode, many single-shell carbon nanotubes of 1-2 nm diameter which appear in the soot, webs, threads (in the reactor chamber) and also on a collaret that forms around the conventional deposit containing multi-shell nanotubes. When the metal is pure manganese powder, we obtain multi-layer hollow carbon fibers in the soot similar to the carbon fibers grown by catalytic chemical vapor deposition. Furthermore, many fibers have a good portion of the length filled with metal. We present here high-resolution transmission electron microscopy images of these structures. (orig.)

Fractal and digital image processing to determine the degree of dispersion of carbon nanotubes

International Nuclear Information System (INIS)

Liang, Xiao-ning; Li, Wei

2016-01-01

The degree of dispersion is an important parameter to quantitatively study properties of carbon nanotube composites. Among the many methods for studying dispersion, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy are the most commonly used, intuitive, and convincing methods. However, they have the disadvantage of not being quantitative. To overcome this disadvantage, the fractal theory and digital image processing method can be used to provide a quantitative analysis of the morphology and properties of carbon nanotube composites. In this paper, the dispersion degree of carbon nanotubes was investigated using two fractal methods, namely, the box-counting method and the differential box-counting method. On the basis of the results, we propose a new method for the quantitative characterization of the degree of dispersion of carbon nanotubes. This hierarchical grid method can be used as a supplementary method, and can be combined with the fractal calculation method. Thus, the accuracy and effectiveness of the quantitative characterization of the dispersion degree of carbon nanotubes can be improved. (The outer diameter of the carbon nanotubes is about 50 nm; the length of the carbon nanotubes is 10–20 μm.)

Fractal and digital image processing to determine the degree of dispersion of carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Liang, Xiao-ning, E-mail: xnliang0506@163.com; Li, Wei, E-mail: 1099006@mail.dhu.edu.cn, E-mail: liwei@dhu.edu.cn, E-mail: waiwentougao@outlook.com [Donghua University, College of Textiles (China)

2016-05-15

The degree of dispersion is an important parameter to quantitatively study properties of carbon nanotube composites. Among the many methods for studying dispersion, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy are the most commonly used, intuitive, and convincing methods. However, they have the disadvantage of not being quantitative. To overcome this disadvantage, the fractal theory and digital image processing method can be used to provide a quantitative analysis of the morphology and properties of carbon nanotube composites. In this paper, the dispersion degree of carbon nanotubes was investigated using two fractal methods, namely, the box-counting method and the differential box-counting method. On the basis of the results, we propose a new method for the quantitative characterization of the degree of dispersion of carbon nanotubes. This hierarchical grid method can be used as a supplementary method, and can be combined with the fractal calculation method. Thus, the accuracy and effectiveness of the quantitative characterization of the dispersion degree of carbon nanotubes can be improved. (The outer diameter of the carbon nanotubes is about 50 nm; the length of the carbon nanotubes is 10–20 μm.)

Synthesis of gold nano-catalysts supported on carbon nanotubes by using electroless plating technique

International Nuclear Information System (INIS)

Ma Xicheng; Li Xia; Lun Ning; Wen Shulin

2006-01-01

Gold nanoparticles supported on carbon nanotubes were prepared by using electroless plating technique. High-resolution transmission electron microscopy (HRTEM) has shown that spherical gold nanoparticles were homogeneously dispersed on the surfaces of the carbon nanotubes with a distribution of particle sizes sharply at around 3-4 nm in diameter. The results presented in this work will probably provide new catalysts with better performances

Stability and signatures of biexcitons in carbon nanotubes

DEFF Research Database (Denmark)

Pedersen, Thomas Garm; Pedersen, Kjeld; Cornean, Horia Decebal

2005-01-01

The linear optical properties of semiconducting carbon nanotubes are dominated by quasi-one-dimensional excitons formed by single electron-hole pairs. Hence, the nonlinear response at high pump levels most likely leads to the formation of exciton complexes involving several electron-hole pairs....... Such complexes would threfore play an important role in e.g. lasing applications. We demonstrate here that the biexciton complex is surprisingly stable for nanotubes in a wide diameter range. Theoretical predictions for the signature of such states in pump-probe spectroscopy are presented....

The growth of aligned carbon nanotubes on quartz substrate by spray pyrolysis of hexane

International Nuclear Information System (INIS)

Sadeghian, Zahra

2008-01-01

Vertically aligned multiwall carbon nanotubes were grown by spray pyrolysis of hexane as the carbon source in the presence of ferrocene as catalyst precursor on a quartz substrate. In recent work we used optimal experimental parameters for the feeding method, reactor conditions, reaction temperature and time, concentration of catalyst and flow rate of feed and gas. The process parameters were chosen so as to obtain multiwall carbon nanotubes and aligned multiwall carbon nanotubes. The tubes are around 15-80 nm in diameter. The morphology and structure of the samples were characterized by x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses

Electroluminescence from single-wall carbon nanotube network transistors.

Science.gov (United States)

Adam, E; Aguirre, C M; Marty, L; St-Antoine, B C; Meunier, F; Desjardins, P; Ménard, D; Martel, R

2008-08-01

The electroluminescence (EL) properties from single-wall carbon nanotube network field-effect transistors (NNFETs) and small bundle carbon nanotube field effect transistors (CNFETs) are studied using spectroscopy and imaging in the near-infrared (NIR). At room temperature, NNFETs produce broad (approximately 180 meV) and structured NIR spectra, while they are narrower (approximately 80 meV) for CNFETs. EL emission from NNFETs is located in the vicinity of the minority carrier injecting contact (drain) and the spectrum of the emission is red shifted with respect to the corresponding absorption spectrum. A phenomenological model based on a Fermi-Dirac distribution of carriers in the nanotube network reproduces the spectral features observed. This work supports bipolar (electron-hole) current recombination as the main mechanism of emission and highlights the drastic influence of carrier distribution on the optoelectronic properties of carbon nanotube films.

Lithium storage performance of carbon nanotubes prepared from polyaniline for lithium-ion batteries

International Nuclear Information System (INIS)

Xiang Xiaoxia; Huang Zhengzheng; Liu Enhui; Shen Haijie; Tian Yingying; Xie Hui; Wu Yuhu; Wu Zhilian

2011-01-01

Highlights: → Polyaniline nanotube is synthesized by the self-assembly method in aqueous media. → Carbon nanotubes were prepared from polyaniline nanotube by physical activation. → Activation leads to large surface area, and surface nitrogen and oxygen functional groups. → Such physical and chemical properties lead to the good electrochemical properties. → After 20 cycles, a reversible capacity of 728 mAh g -1 was obtained. - Abstract: Carbon nanotubes with large surface area and surface nitrogen and oxygen functional groups are prepared by carbonizing and activating of polyaniline nanotubes, which is synthesized by polymerization of aniline with the self-assembly method in aqueous media. The physicochemical properties of the carbon nanotubes are characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller, elemental analyses and X-ray photoelectron spectroscopy measurements. The surface area and pore diameter are 618.9 m 2 g -1 and 3.10 nm. The electrochemical properties of the carbon nanotubes as anode materials in lithium ion batteries are evaluated. At a current density of 100 mA g -1 , the activated carbon nanotube shows an enormously first discharge capacity of about 1370 mAh g -1 and a charge capacity of 907 mAh g -1 . After 20 cycling tests, the activated carbon nanotube retains a reversible capacity of 728 mAh g -1 . These indicate it may be a promising candidate for an anode material for lithium secondary batteries.

Carbon nanotube yarns as strong flexible conductive capacitive electrodes

NARCIS (Netherlands)

Liu, F.; Wagterveld, R.M.; Gebben, B.; Otto, M.J.; Biesheuvel, P.M.; Hamelers, H.V.M.

2015-01-01

Carbon nanotube (CNT) yarn, consisting of 23 µm diameter CNT filaments, can be used as capacitive electrodes that are long, flexible, conductive and strong, for applications in energy and electrochemical water treatment. We measure the charge storage capacity as function of salt concentration, and

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

77 FR 67336 - Certain Small Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe From Romania...

Science.gov (United States)

2012-11-09

... Carbon and Alloy Seamless Standard, Line and Pressure Pipe From Romania: Final Results of Antidumping... alloy seamless standard, line and pressure pipe from Romania. The period of review is August 1, 2010..., line and pressure pipe from Romania. See Certain Small Diameter Carbon and Alloy Seamless Standard...

Effect of diameter and chirality on the structure and electronic properties of BC2N nanotubes

International Nuclear Information System (INIS)

Akhavan, Mojdeh; Jalili, Seifollah; Schofield, Jeremy

2015-01-01

Highlights: • BC 2 N nanotubes with different diameters and four chirality types are studied. • Two lowest-diameter zigzag BC 2 N tubes are metallic and others are semiconducting. • Band gap of zigzag tubes is more sensitive to diameter compared to armchair tubes. • Even–odd oscillation is observed for the band gap of one kind of zigzag tubes. • The energy and band gap for large-diameter tubes converge to BC 2 N sheet values. - Abstract: Density functional theory calculations are used to investigate a series of BC 2 N nanotubes with a wide range of diameters. Two types of zigzag and two types of armchair nanotubes are studied to survey the effect of diameter and chirality on energetics and electronic properties of nanotubes. Two nanotubes are found to be metallic and others show semiconducting behavior. The diameter is shown to have a greater impact on the band gap of zigzag nanotubes than those of armchair tubes. (n, 0) zigzag nanotubes show an even–odd band gap oscillation, which can be explained by the electron density distribution of the lowest unoccupied crystalline orbital. The stability of the nanotubes is also assessed using strain energies and it is shown that the strain energy does not depend on nanotube type and chirality. In the limit of large diameters, the geometry and band gap of all nanotubes converge to BC 2 N sheet data

Industrial-scale separation of high-purity single-chirality single-wall carbon nanotubes for biological imaging

Science.gov (United States)

Yomogida, Yohei; Tanaka, Takeshi; Zhang, Minfang; Yudasaka, Masako; Wei, Xiaojun; Kataura, Hiromichi

2016-01-01

Single-chirality, single-wall carbon nanotubes are desired due to their inherent physical properties and performance characteristics. Here, we demonstrate a chromatographic separation method based on a newly discovered chirality-selective affinity between carbon nanotubes and a gel containing a mixture of the surfactants. In this system, two different selectivities are found: chiral-angle selectivity and diameter selectivity. Since the chirality of nanotubes is determined by the chiral angle and diameter, combining these independent selectivities leads to high-resolution single-chirality separation with milligram-scale throughput and high purity. Furthermore, we present efficient vascular imaging of mice using separated single-chirality (9,4) nanotubes. Due to efficient absorption and emission, blood vessels can be recognized even with the use of ∼100-fold lower injected dose than the reported value for pristine nanotubes. Thus, 1 day of separation provides material for up to 15,000 imaging experiments, which is acceptable for industrial use. PMID:27350127

Source brightness and useful beam current of carbon nanotubes and other very small emitters

International Nuclear Information System (INIS)

Kruit, P.; Bezuijen, M.; Barth, J.E.

2006-01-01

The potential application of carbon nanotubes as electron sources in electron microscopes is analyzed. The resolution and probe current that can be obtained from a carbon nanotube emitter in a low-voltage scanning electron microscope are calculated and compared to the state of the art using Schottky electron sources. Many analytical equations for probe-size versus probe-current relations in different parameter regimes are obtained. It is shown that for most carbon nanotube emitters, the gun lens aberrations are larger than the emitters' virtual source size and thus restrict the microscope's performance. The result is that the advantages of the higher brightness of nanotube emitters are limited unless the angular emission current is increased over present day values or the gun lens aberrations are decreased. For some nanotubes with a closed cap, it is known that the emitted electron beam is coherent over the full emission cone. We argue that for such emitters the parameter ''brightness'' becomes meaningless. The influence of phase variations in the electron wave front emitted from such a nanotube emitter on the focusing of the electron beam is analyzed

A density functional study of nitrogen adsorption in single-wall carbon nanotubes

International Nuclear Information System (INIS)

Zhu Jie; Wang Yao; Li Wenjun; Wei Fei; Yu Yangxin

2007-01-01

An understanding of the adsorption behaviour of nitrogen in single-wall carbon nanotubes (SWCNTs) is necessary for obtaining information on its pores by nitrogen adsorption manometry. Non-local density functional theory was used to simulate nitrogen adsorption behaviour, including the adsorption isotherms, equilibrium density profiles and potential energy of the nitrogen molecules at 77 K, inside SWCNTs with diameters ranging from 0.696 to 3.001 nm. With increasing diameter, nitrogen adsorption changes from continuous filling in one dimension to a two-stage adsorption that corresponds to monolayer formation followed by multilayer condensation. The average density of the adsorbed nitrogen and the density profiles, especially in small diameter SWCNTs, were used to analyse the adsorbate phase at the saturation pressure. The results indicate that the type of pore filling depends primarily on the ratio of the SWCNT diameter to the adsorbate molecular diameter. The filling of SWCNTs is not a simple capillary condensation process, but is dominated by geometrical limitation

Solution-phase synthesis of chromium-functionalized single-walled carbon nanotubes

KAUST Repository

Kalinina, Irina V.; Al-Hadeethi, Yas Fadel; Bekyarova, Elena; Zhao, Chao; Wang, Qingxiao; Zhang, Xixiang; Al-Zahrani, Ali; Al-Agel, Faisal Abdulaziz M; Al-Marzouki, Fahad M.; Haddon, Robert C.

2015-01-01

The solution phase reactions of single-walled carbon nanotubes (SWNTs) with Cr(CO)6 and benzene-Cr(CO)3 can lead to the formation of small chromium clusters. The cluster size can be varied from less than 1 nm to about 4 nm by increasing the reaction time. TEM images suggest that the clusters are deposited predominantly on the exterior walls of the nanotubes. TGA analysis was used to obtain the Cr content and carbon to chromium ratio in the Cr-complexed SWNTs. It is suggested that the carbon nanotube benzenoid structure templates the condensation of chromium atoms and facilitates the loss of carbon monoxide leading to well defined metal clusters.

Solution-phase synthesis of chromium-functionalized single-walled carbon nanotubes

KAUST Repository

Kalinina, Irina V.

2015-03-01

The solution phase reactions of single-walled carbon nanotubes (SWNTs) with Cr(CO)6 and benzene-Cr(CO)3 can lead to the formation of small chromium clusters. The cluster size can be varied from less than 1 nm to about 4 nm by increasing the reaction time. TEM images suggest that the clusters are deposited predominantly on the exterior walls of the nanotubes. TGA analysis was used to obtain the Cr content and carbon to chromium ratio in the Cr-complexed SWNTs. It is suggested that the carbon nanotube benzenoid structure templates the condensation of chromium atoms and facilitates the loss of carbon monoxide leading to well defined metal clusters.

Wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes with surface and nonlocal effects

Science.gov (United States)

Zhen, Ya-Xin

2017-02-01

In this paper, the transverse wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes is investigated based on nonlocal elasticity theory with consideration of surface effect. The governing equation is formulated utilizing nonlocal Euler-Bernoulli beam theory and Kelvin-Voigt model. Explicit wave dispersion relation is developed and wave phase velocities and frequencies are obtained. The effect of the fluid flow velocity, structural damping, surface effect, small scale effects and tube diameter on the wave propagation properties are discussed with different wave numbers. The wave frequency increases with the increase of fluid flow velocity, but decreases with the increases of tube diameter and wave number. The effect of surface elasticity and residual surface tension is more significant for small wave number and tube diameter. For larger values of wave number and nonlocal parameters, the real part of frequency ratio raises.

Ultrafast excitation energy transfer from encapsulated quaterrylene to single-walled carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Koyama, Takeshi, E-mail: koyama@nuap.nagoya-u.ac.jp [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Tsunekawa, Takuya [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Saito, Takeshi [Research Center for Advanced Carbon Materials, AIST, Tsukuba, Ibaraki 305-8565 (Japan); Asaka, Koji; Saito, Yahachi [Department of Quantum Engineering, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Kishida, Hideo [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Nakamura, Arao [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192 (Japan)

2016-01-15

We investigate excitation energy transfer from an encapsulated quaterrylene molecule to a single-walled carbon nanotube by means of femtosecond pump-probe spectroscopy. The time constant of energy transfer becomes shorter with increasing average diameter of nanotube: 1.4±0.2 ps for 1.0 nm, 1.1±0.2 ps for 1.4 nm, and 0.4±0.1 ps for 1.8 nm. The observed behavior is discussed considering the distance of less than 1 nm between the molecule and the nanotube wall. - Highlights: • Dynamical properties of excited states in quaterrylene/SWNT composites were studied. • Excitation energy transfer occurs in the time range of 0.4-1.4 ps. • The transfer rate depends on the nanotube diameter, i.e. molecule-nanotube wall distance. • This dependence indicates the feature of excitation energy transfer on the nanoscale.

Fabrication and characterization of reaction bonded silicon carbide/carbon nanotube composites

International Nuclear Information System (INIS)

Thostenson, Erik T; Karandikar, Prashant G; Chou, T.-W.

2005-01-01

Carbon nanotubes have generated considerable excitement in the scientific and engineering communities because of their exceptional mechanical and physical properties observed at the nanoscale. Carbon nanotubes possess exceptionally high stiffness and strength combined with high electrical and thermal conductivities. These novel material properties have stimulated considerable research in the development of nanotube-reinforced composites (Thostenson et al 2001 Compos. Sci. Technol. 61 1899, Thostenson et al 2005 Compos. Sci. Technol. 65 491). In this research, novel reaction bonded silicon carbide nanocomposites were fabricated using melt infiltration of silicon. A series of multi-walled carbon nanotube-reinforced ceramic matrix composites (NT-CMCs) were fabricated and the structure and properties were characterized. Here we show that carbon nanotubes are present in the as-fabricated NT-CMCs after reaction bonding at temperatures above 1400 deg. C. Characterization results reveal that a very small volume content of carbon nanotubes, as low as 0.3 volume %, results in a 75% reduction in electrical resistivity of the ceramic composites. A 96% decrease in electrical resistivity was observed for the ceramics with the highest nanotube volume fraction of 2.1%

Modifying the electronic and optical properties of carbon nanotubes

Science.gov (United States)

Kinder, Jesse M.

The intrinsic electronic and optical properties of carbon nanotubes make them promising candidates for circuit elements and LEDs in nanoscale devices. However, applied fields and interactions with the environment can modify these intrinsic properties. This dissertation is a theoretical study of perturbations to an ideal carbon nanotube. It illustrates how transport and optical properties of carbon nanotubes can be adversely affected or intentionally modified by the local environment. The dissertation is divided into three parts. Part I analyzes the effect of a transverse electric field on the single-electron energy spectrum of semiconducting carbon nanotubes. Part II analyzes the effect of the local environment on selection rules and decay pathways relevant to dark excitons. Part III is a series of 26 appendices. Two different models for a transverse electric field are introduced in Part I. The first is a uniform field perpendicular to the nanotube axis. This model suggests the field has little effect on the band gap until it exceeds a critical value that can be tuned with strain or a magnetic field. The second model is a transverse field localized to a small region along the nanotube axis. The field creates a pair of exponentially localized bound states but has no effect on the band gap for particle transport. Part II explores the physics of dark excitons in carbon nanotubes. Two model calculations illustrate the effect of the local environment on allowed optical transitions and nonradiative recombination pathways. The first model illustrates the role of inversion symmetry in the optical spectrum. Broken inversion symmetry may explain low-lying peaks in the exciton spectrum of boron nitride nanotubes and localized photoemission around impurities and interfaces in carbon nanotubes. The second model in Part II suggests that free charge carriers can mediate an efficient nonradiative decay process for dark excitons in carbon nanotubes. The appendices in Part III

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.

Improved synthesis of carbon nanotubes with junctions and of single ...

Indian Academy of Sciences (India)

Unknown

Abstract. Pyrolysis of thiophene over nickel nanoparticles dispersed on silica is shown to yield Y- junction carbon nanotubes with smaller diameters than those obtained by the pyrolysis of organometallic- thiophene mixtures. In the presence of water vapour, the pyrolysis of organometallic-hydrocarbon mixtures.

Preparation of carbon nanotubes by MPECVD

International Nuclear Information System (INIS)

El-Shazly Duraia, M.A.; Mansorov, Z.A.; Tokmoldin, S.Zh.; Klimenov, V.V.; Nevmerzhitsky, I.S.; Dochshanov, A.M.

2009-01-01

measurements were performed at room temperature under the excitation laser with wavelength of 325 nm. There are two intensive peaks near the ultraviolet range (411 nm, 433 nm for the sample at growth temperature 600 C ). The sample at growth temperature 600 C represents the optimum sample for the PL among the other samples. It was observed the peaks positions shits to the higher wavelengths value as the growth temperature increases. Through the experiments it was observed that the photoluminescence intensity is very sensitive to the change in the angle. For example, the samples of vertically carbon nanotubes gives the maximum PL intensity at a very small angle with respect to the laser beam and the intensity gradually decreased as the angle increased, on the other hand, the samples with the horizontal carbon nanotubes gives the maximum PL intensity when the sample approximately parallel to the laser beam. This strong polarization dependence may be due to the quantum confinement effect through the diameter of the carbon nanotube. The effect of the annealing temperature on the photoluminescence was also studied. The experiments showed that the photoluminescence is completely disappeared after the annealing at 600 C in air for five minutes. The effect of the gas pressure on the CNTs was also investigated. The gradual increase in the Raman intensity for all peaks was observed, which indicates the enhancement of the CNTs quality and amount with the gas pressure increasing. When the gas pressure is low, the growth rate of the CNTs was also low because the a lot amount of carbon atoms at lower pressure may fly for long time and does not deposited at the substrate. (author)

Compatible above-ground biomass equations and carbon stock estimation for small diameter Turkish pine (Pinus brutia Ten.).

Science.gov (United States)

Sakici, Oytun Emre; Kucuk, Omer; Ashraf, Muhammad Irfan

2018-04-15

Small trees and saplings are important for forest management, carbon stock estimation, ecological modeling, and fire management planning. Turkish pine (Pinus brutia Ten.) is a common coniferous species and comprises 25.1% of total forest area of Turkey. Turkish pine is also important due to its flammable fuel characteristics. In this study, compatible above-ground biomass equations were developed to predict needle, branch, stem wood, and above-ground total biomass, and carbon stock assessment was also described for Turkish pine which is smaller than 8 cm diameter at breast height or shorter than breast height. Compatible biomass equations are useful for biomass prediction of small diameter individuals of Turkish pine. These equations will also be helpful in determining fire behavior characteristics and calculating their carbon stock. Overall, present study will be useful for developing ecological models, forest management plans, silvicultural plans, and fire management plans.

Functionalized carbon nanotubes and nanofibers for biosensing applications

Energy Technology Data Exchange (ETDEWEB)

Wang, Jun; Lin, Yuehe

2008-07-30

This review summarizes the recent advances of carbon nanotube (CNT) and carbon nanofiber (CNF)-based electrochemical biosensors with an emphasis on the applications of CNTs. Carbon nanotubes and carbon nanofibers have unique electric, electrocatalytic, and mechanical properties which make them efficient materials for the use in electrochemical biosensor development. In this article, the functionalization of CNTs for biosensors is simply discussed. The electrochemical biosensors based on CNT and their various applications, e.g., measurement of small biological molecules and environmental pollutants, detection of DNA, and immunosensing of disease biomarkers, are reviewed. Moreover, the development of carbon nanofiber-based electrochemical biosensors and their applications are outlined. Finally, some challenges are discussed in the conclusion.

Thermal Analysis of Copper-Titanium-Multiwall Carbon Nanotube Composites.

Science.gov (United States)

Hamamda, Smail; Jari, Ahmed; Revo, S; Ivanenko, K; Jari, Youcef; Avramenko, T

2017-12-01

The aim of this research is the thermostructural study of Cu-Ti, Cu-Ti 1 vol% multiwall carbon nanotubes (MWCNTs) and Cu-Ti 3 vol% MWCNTs. Several investigation techniques were used to achieve this objective. Dilatometric data show that the coefficient of thermal expansion of the nanocomposite containing less multiwall carbon nanotubes is linear and small. The same nanocomposite exhibits regular heat transfer and weak mass exchange with the environment. Raman spectroscopy shows that the nanocomposite with more MWCNTs contains more defects. This implies that the carbon nanotubes have better dispersion in Cu-Ti 1 vol% MWCNTs. Infrared spectroscopy reveals that Cu-Ti 1 vol% MWCNTs has better crystallinity than Cu-Ti 3 vol% MWCNTs.

Carbon Nanotubes and Modern Nanoagriculture

KAUST Repository

Serag, Maged F.

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

Enhanced Photocurrent Efficiency of a Carbon Nanotube Embedded in a Photonic Structure

Energy Technology Data Exchange (ETDEWEB)

Wong, Bryan M. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Materials Science

2008-08-01

One of the most rapidly-growing areas in nanoscience is the ability to artificially manipulate optical and electrical properties at the nanoscale. In particular, nanomaterials such as single-wall carbon nanotubes offer enhanced methods for converting infrared light to electrical energy due to their unique one-dimensional electronic properties. However, in order for this energy conversion to occur, a realistic nanotube device would require high-intensity light to be confined on a nanometer scale. This arises from the fact that the diameter of a single nanotube is on the order of a nanometer, and infrared light from an external source must be tightly focused on the narrow nanotube for efficient energy conversion. To address this problem, I calculate the theoretical photocurrent of a nanotube p-n junction illuminated by a highly-efficient photonic structure. These results demonstrate the utility of using a photonic structure to couple large-scale infrared sources with carbon nanotubes while still retaining all the unique optoelectronic properties found at the nanoscale.

The impact of different multi-walled carbon nanotubes on the X-band microwave absorption of their epoxy nanocomposites.

Science.gov (United States)

Che, Bien Dong; Nguyen, Bao Quoc; Nguyen, Le-Thu T; Nguyen, Ha Tran; Nguyen, Viet Quoc; Van Le, Thang; Nguyen, Nieu Huu

2015-01-01

Carbon nanotube (CNT) characteristics, besides the processing conditions, can change significantly the microwave absorption behavior of CNT/polymer composites. In this study, we investigated the influence of three commercial multi-walled CNT materials with various diameters and length-to-diameter aspect ratios on the X-band microwave absorption of epoxy nanocomposites with CNT contents from 0.125 to 2 wt%, prepared by two dispersion methods, i.e. in solution with surfactant-aiding and via ball-milling. The laser diffraction particle size and TEM analysis showed that both methods produced good dispersions at the microscopic level of CNTs. Both a high aspect ratio resulting in nanotube alignment trend and good infiltration of the matrix in the individual nanotubes, which was indicated by high Brookfield viscosities at low CNT contents of CNT/epoxy dispersions, are important factors to achieve composites with high microwave absorption characteristics. The multi-walled carbon nanotube (MWCNT) with the largest aspect ratio resulted in composites with the best X-band microwave absorption performance, which is considerably better than that of reported pristine CNT/polymer composites with similar or lower thicknesses and CNT loadings below 4 wt%. A high aspect ratio of CNTs resulting in microscopic alignment trend of nanotubes as well as a good level of micro-scale CNT dispersion resulting from good CNT-matrix interactions are crucial to obtain effective microwave absorption performance. This study demonstrated that effective radar absorbing MWCNT/epoxy nanocomposites having small matching thicknesses of 2-3 mm and very low filler contents of 0.25-0.5 wt%, with microwave energy absorption in the X-band region above 90% and maximum absorption peak values above 97%, could be obtained via simple processing methods, which is promising for mass production in industrial applications. Graphical AbstractComparison of the X-band microwave reflection loss of epoxy composites of

Thermoplastic polyurethane and multi-walled carbon nanotubes nanocomposites for electrostatic dissipation

International Nuclear Information System (INIS)

Lavall, Rodrigo L.; Sales, Juliana A. de; Borges, Raquel S.; Calado, Hallen D. R.; Machado, Jose C.; Windmoeller, Dario; Silva, Glaura G.; Lacerda, Rodrigo G.; Ladeira, Luiz O.

2010-01-01

Polyurethane/multi-walled carbon nanotube (MWCNT) nanocomposites have been prepared with nanotube concentrations between 0.01 wt% and 1 wt%. MWCNT as-synthesized samples with ∼74 nm diameter and ∼7 mm length were introduced by solution processing in the polyurethane matrix. Scanning electron microscopy (SEM) images demonstrated good dispersion and adhesion of the CNTs to the polymeric matrix. The C=O stretching band showed evidence of perturbation of the hydrogen interaction between urethanic moieties in the nanocomposites as compared to pure TPU. Differential scanning calorimetry and positron annihilation lifetime spectroscopy measurements allowed the detection of glass transition displacement with carbon nanotube addition. Furthermore, the electrical conductivity of the nanocomposites was significantly increased with the addition of CNT. (author)

Morphological control of three-dimensional carbon nanotube anode for high-capacity lithium-ion battery

Science.gov (United States)

Kang, Chiwon; Lee, Hoo-Jeong

2018-05-01

In this paper, we report the results of modulating the processing conditions (mainly, temperature) of a two-step method consisting of sputtering deposition of a Ni catalytic layer and chemical vapor deposition (CVD) of carbon nanotubes (CNTs) on a three-dimensional (3D)-structured Cu mesh to control the morphology of CNTs for advanced Li-ion battery (LIB) applications. We disclosed that CNT growth at a low temperature (700 °C) produced small-diameter CNTs (CNT_S) with an average diameter of ∼20 nm, while that at a high temperature (750 °C) produced large-diameter CNTs (CNT_L) with an average diameter of 200–300 nm. The high-resolution transmission electron microscopy (HR-TEM) and Raman analyses manifested poorly crystalline CNTs for both samples. CNTS showed a specific capacity of 476 mAh g‑1, which is ∼176% superior to that of CNTL (271 mAh g‑1) and ∼128% higher than the theoretical capacity of the state-of-the-art graphites and recently reported nanostructured carbon-based anode materials.

Carbon nanotube materials for hydrogen storage

Energy Technology Data Exchange (ETDEWEB)

Dillon, A.C.; Parilla, P.A.; Jones, K.M.; Riker, G.; Heben, M.J. [National Renewable Energy Lab., Golden, CO (United States)

1998-08-01

Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work the authors developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be {approximately} 5 times higher than for adsorption on planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. This year the authors have made significant advances in synthesis and characterization of SWNT materials so that they can now prepare gram quantities of high-purity SWNT samples and measure and control the diameter distribution of the tubes by varying key parameters during synthesis. They have also developed methods which purify nanotubes and cut nanotubes into shorter segments. These capabilities provide a means for opening the tubes which were unreactive to the oxidation methods that successfully opened tubes, and offer a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. They also performed temperature programmed desorption spectroscopy on high purity carbon nanotube material obtained from collaborator Prof. Patrick Bernier and finished construction of a high precision Seivert`s apparatus which will allow the hydrogen pressure-temperature-composition phase diagrams to be evaluated for SWNT materials.

A carbon nanotube-based pressure sensor

International Nuclear Information System (INIS)

Karimov, Kh S; Saleem, M; Khan, Adam; Qasuria, T A; Mateen, A; Karieva, Z M

2011-01-01

In this study, a carbon nanotube (CNT)-based Al/CNT/Al pressure sensor was designed, fabricated and investigated. The sensor was fabricated by depositing CNTs on an adhesive elastic polymer tape and placing this in an elastic casing. The diameter of multiwalled nanotubes varied between 10 and 30 nm. The nominal thickness of the CNT layers in the sensors was in the range ∼300-430 μm. The inter-electrode distance (length) and the width of the surface-type sensors were in the ranges 4-6 and 3-4 mm, respectively. The dc resistance of the sensors decreased 3-4 times as the pressure was increased up to 17 kN m -2 . The resistance-pressure relationships were simulated.

Role of intertube interactions in double- and triple-walled carbon nanotubes.

Science.gov (United States)

Hirschmann, Thomas Ch; Araujo, Paulo T; Muramatsu, Hiroyuki; Rodriguez-Nieva, Joaquin F; Seifert, Max; Nielsch, Kornelius; Kim, Yoong Ahm; Dresselhaus, Mildred S

2014-02-25

Resonant Raman spectroscopy studies are performed to access information about the intertube interactions and wall-to-wall distances in double- and triple-walled carbon nanotubes. Here, we explain how the surroundings of the nanotubes in a multiwalled system influence their radial breathing modes. Of particular interest, the innermost tubes in double- and triple-walled carbon nanotube systems are shown to be significantly shielded from environmental interactions, except for those coming from the intertube interaction with their own respective host tubes. From a comparison of the Raman results for bundled as well as individual fullerene-peapod-derived double- and triple-walled carbon nanotubes, we observe that metallic innermost tubes, when compared to their semiconducting counterparts, clearly show weaker intertube interactions. Additionally, we discuss a correlation between the wall-to-wall distances and the frequency upshifts of the radial breathing modes observed for the innermost tubes in individual double- and triple-walled carbon nanotubes. All results allow us to contemplate fundamental properties related to DWNTs and TWNTs, as for example diameter- and chirality-dependent intertube interactions. We also discuss differences in fullerene-peapod-derived and chemical vapor deposition grown double- and triple-walled systems with the focus on mechanical coupling and interference effects.

All carbon nanotubes are not created equal

International Nuclear Information System (INIS)

Geohegan, David B.; Puretzky, Alexander A.; Rouleau, Christopher M.

2010-01-01

This chapter presents the various factors that enter into consideration when choosing the source of carbon nanotubes for a specific application. Carbon nanotubes are giant molecules made of pure carbon. They have captured the imagination of the scientific community by the unique structure that provides superior physical, chemical, and electrical properties. However, a surprisingly wide disparity exists between the intrinsic properties determined under ideal conditions and the properties that carbon nanotubes exhibit in real world situations. The lack of uniformity in carbon nanotube properties is likely to be the main obstacle holding back the development of carbon nanotube applications. This tutorial addresses the nonuniformity of carbon nanotube properties from the synthesis standpoint. This synthesis-related nonuniformity is on top of the intrinsic chirality distribution that gives the ∼1:2 ratio of metallic to semiconducting nanotubes. From the standpoint of carbon bonding chemistry the variation in the quality and reproducibility of carbon nanotube materials is not unexpected. It is an intrinsic feature that is related to the metastability of carbon structures. The extent to which this effect is manifested in carbon nanotube formation is governed by the type and the kinetics of the carbon nanotube synthesis reaction. Addressing this variation is critical if nanotubes are to live up to the potential already demonstrated by their phenomenal physical properties.

Molecular Dynamics Simulation of Damage to Coiled Carbon Nanotubes under C Ion Irradiation

International Nuclear Information System (INIS)

Zhou Bin; Zhang Wei; Gong Wen-Bin; Wang Song; Ren Cui-Lan; Wang Cheng-Bin; Zhu Zhi-Yuan; Huai Ping

2013-01-01

The stability of coiled carbon nanotubes under C ion irradiation is investigated by molecular dynamics simulations. The defect statistics shows that small curvature coiled carbon nanotubes have better radiation tolerance than normal straight carbon nanotubes. To understand the effect of the curvature on defect production, the threshold displacement energies for the upper and lower walls, as well as those for the side parts, are calculated. The results show that the lower wall has better radiation tolerance than the upper wall. For the upper wall, a small increase in the curvature of nanotube axis gives rise to an increase in the radiation tolerance and then a decrease with the curvature becomes larger. However, for the lower wall, as the curvature of the nanotube axis increases, the radiation tolerance increases as the bonds compressed slightly in our simulation

Synthesis of an ultradense forest of vertically aligned triple-walled carbon nanotubes of uniform diameter and length using hollow catalytic nanoparticles.

Science.gov (United States)

Baliyan, Ankur; Nakajima, Yoshikata; Fukuda, Takahiro; Uchida, Takashi; Hanajiri, Tatsuro; Maekawa, Toru

2014-01-22

It still remains a crucial challenge to actively control carbon nanotube (CNT) structure such as the alignment, area density, diameter, length, chirality, and number of walls. Here, we synthesize an ultradense forest of CNTs of a uniform internal diameter by the plasma-enhanced chemical vapor deposition (PECVD) method using hollow nanoparticles (HNPs) modified with ligand as a catalyst. The diameters of the HNPs and internal cavities in the HNPs are uniform. A monolayer of densely packed HNPs is self-assembled on a silicon substrate by spin coating. HNPs shrink via the collapse of the internal cavities and phase transition from iron oxide to metallic iron in hydrogen plasma during the PECVD process. Agglomeration of catalytic NPs is avoided on account of the shrinkage of the NPs and ligand attached to the NPs. Diffusion of NPs into the substrate, which would inactivate the growth of CNTs, is also avoided on account of the ligand. As a result, an ultradense forest of triple-walled CNTs of a uniform internal diameter is successfully synthesized. The area density of the grown CNTs is as high as 0.6 × 10(12) cm(-2). Finally, the activity of the catalytic NPs and the NP/carbon interactions during the growth process of CNTs are investigated and discussed. We believe that the present approach may make a great contribution to the development of an innovative synthetic method for CNTs with selective properties.

Method for producing carbon nanotubes

Science.gov (United States)

Phillips, Jonathan [Santa Fe, NM; Perry, William L [Jemez Springs, NM; Chen, Chun-Ku [Albuquerque, NM

2006-02-14

Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.

Carbon Nanotubes: A Review on Structure and Their Interaction with Proteins

Directory of Open Access Journals (Sweden)

N. Saifuddin

2013-01-01

Full Text Available Carbon nanotubes (CNTs are allotropes of carbon with a nanostructure that can have a length-to-diameter ratio greater than 1,000,000. Techniques have been developed to produce nanotubes in sizeable quantities, including arc discharge, laser ablation, and chemical vapor deposition. Developments in the past few years have illustrated the potentially revolutionizing impact of nanomaterials, especially in biomedical imaging, drug delivery, biosensing, and the design of functional nanocomposites. Methods to effectively interface proteins with nanomaterials for realizing these applications continue to evolve. The high surface-to-volume ratio offered by nanoparticles resulted in the concentration of the immobilized entity being considerably higher than that afforded by other materials. There has also been an increasing interest in understanding the influence of nanomaterials on the structure and function of proteins. Various immobilization methods have been developed, and in particular, specific attachment of enzymes on carbon nanotubes has been an important focus of attention. With the growing attention paid to cascade enzymatic reaction, it is possible that multienzyme coimmobilization would be one of the next goals in the future. In this paper, we focus on advances in methodology for enzyme immobilization on carbon nanotubes.

Functionalized carbon nanotubes containing isocyanate groups

International Nuclear Information System (INIS)

Zhao Chungui; Ji Lijun; Liu Huiju; Hu Guangjun; Zhang Shimin; Yang Mingshu; Yang Zhenzhong

2004-01-01

Functionalized carbon nanotubes containing isocyanate groups can extend the nanotube chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized carbon nanotubes containing highly reactive isocyanate groups on its surface via the reaction between toluene 2,4-diisocyanate and carboxylated carbon nanotubes. Fourier-transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed that reactive isocyanate groups were covalently attached to carbon nanotubes. The content of isocyanate groups were determined by chemical titration and thermogravimetric analysis (TGA)

Growth and field emission properties of one-dimensional carbon composite structure consisting of vertically aligned carbon nanotubes and nanocones

International Nuclear Information System (INIS)

Zhang Hongxin; Feng, Peter X; Fonseca, Luis; Morell, Gerardo; Makarov, Vladimir I; Weiner, Brad R

2009-01-01

A simple approach is demonstrated for quickly growing a large-area aligned carbon composite nanostructure consisting of vertically aligned nanotubes and nanocones by the catalyst-assisted pulsed laser deposition techniques. The pyrolytic graphite was used as carbon source. The carbon nanocones were first grown on the molybdenum substrate with Ni catalysts. The carbon nanotubes have a uniform shape and length, aligned vertically on carbon nanocones, and the average diameter is about 7 nm. The special carbon composite arrays exhibit excellent field emission behaviours. The long-term field emission current stability of the one-dimensioned carbon nanostructure has also been investigated. No obvious current density decay was observed after a 10-day continuous experiment, indicating the super stability of the sample as cathode material.

Continuous carbon nanotube reinforced composites.

Science.gov (United States)

Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M

2008-09-01

Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.

Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume: An Investigation of the Metal Catalyst by Laser Ablation Atomic Fluorescence Spectroscopy

Science.gov (United States)

deBoer, Gary; Scott, Carl

2003-01-01

Carbon nanotubes, elongated molecular tubes with diameters of nanometers and lengths in microns, hold great promise for material science. Hopes for super strong light-weight material to be used in spacecraft design is the driving force behind nanotube work at JSC. The molecular nature of these materials requires the appropriate tools for investigation of their structure, properties, and formation. The mechanism of nanotube formation is of particular interest because it may hold keys to controlling the formation of different types of nanotubes and allow them to be produced in much greater quantities at less cost than is currently available. This summer's work involved the interpretation of data taken last summer and analyzed over the academic year. The work involved diagnostic studies of carbon nanotube formation processes occurring in a laser-produced plume. Laser ablation of metal doped graphite to produce a plasma plume in which carbon nanotubes self assemble is one method of making carbon nanotube. The laser ablation method is amenable to applying the techniques of laser spectroscopy, a powerful tool for probing the energies and dynamics of atomic and molecular species. The experimental work performed last summer involved probing one of the metal catalysts, nickel, by laser induced fluorescence. The nickel atom was studied as a function of oven temperature, probe laser wavelength, time after ablation, and position in the laser produced plume. This data along with previously obtained data on carbon was analyzed over the academic year. Interpretations of the data were developed this summer along with discussions of future work. The temperature of the oven in which the target is ablated greatly influences the amount of material ablated and the propagation of the plume. The ablation conditions and the time scale of atomic and molecular lifetimes suggest that initial ablation of the metal doped carbon target results in atomic and small molecular species. The metal

DNA-templated synthesis of Pt nanoparticles on single-walled carbon nanotubes.

Science.gov (United States)

Dong, Lifeng

2009-11-18

A series of electron microscopy characterizations demonstrate that single-stranded deoxyribonucleic acid (ssDNA) can bind to nanotube surfaces and disperse bundled single-walled carbon nanotubes (SWCNTs) into individual tubes. The ssDNA molecules on the nanotube surfaces demonstrate various morphologies, such as aggregated clusters and spiral wrapping around a nanotube with different pitches and spaces, indicating that the morphology of the SWCNT/DNA hybrids is not related solely to the base sequence of the ssDNA or the chirality or the diameter of the nanotubes. In addition to serving as a non-covalent dispersion agent, the ssDNA molecules bonded to the nanotube surface can provide addresses for localizing Pt(II) complexes along the nanotubes. The Pt nanoparticles obtained by a reduction of the Pt2+-DNA adducts are crystals with a size of direct ethanol/methanol fuel cells and nanoscale electronics.

High-performance carbon nanotube-implanted mesoporous carbon spheres for supercapacitors with low series resistance

Energy Technology Data Exchange (ETDEWEB)

Yi, Bin [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Chen, Xiaohua, E-mail: hudacxh62@yahoo.com.cn [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Guo, Kaimin [College of Physics and Electronic Science, Changsha University of Science and Technology (China); Xu, Longshan [Department of Mechanical Engineering, Xiamen University of Technology, Xiamen 361024 (China); Chen, Chuansheng [College of Physics and Electronic Science, Changsha University of Science and Technology (China); Yan, Haimei; Chen, Jianghua [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

2011-11-15

Research highlights: {yields} CNTs-implanted porous carbon spheres are prepared by using gelatin as soft template. {yields} Homogeneously distributed CNTs form a well-develop network in carbon spheres. {yields} CNTs act as a reinforcing backbone assisting the formation of pore structure. {yields} CNTs improve electrical conductivity and specific capacitance of supercapacitor. -- Abstract: Carbon nanotube-implanted mesoporous carbon spheres were prepared by an easy polymerization-induced colloid aggregation method using gelatin as a soft template. Scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption measurements reveal that the materials are mesoporous carbon spheres, with a diameter of {approx}0.5-1.0 {mu}m, a specific surface area of 284 m{sup 2}/g and average pore size of 3.9 nm. Using the carbon nanotube-implanted mesoporous carbon spheres as electrode material for supercapacitors in an aqueous electrolyte solution, a low equivalent series resistance of 0.83 {Omega} cm{sup 2} and a maximum specific capacitance of 189 F/g with a measured power density of 8.7 kW/kg at energy density of 6.6 Wh/kg are obtained.

Passively Q-switched of EDFL employing multi-walled carbon nanotubes with diameter less than 8 nm as saturable absorber

Directory of Open Access Journals (Sweden)

Zuikafly Siti Nur Fatin

2017-01-01

Full Text Available The paper demonstrates passively Q-switched erbium-doped fiber laser implementing multiwalled carbon nanotubes (MWCNTs based saturable absorber. The paper is the first to report the use of the MWCNTs with diameter less than 8 nm as typically, the diameter used is 10 to 20 nm. The MWCNTs is incorporated with water soluble host polymer, polyvinyl alcohol (PVA to produce a MWCNTs polymer composite thin film which is then sandwiched between two fiber connectors. The fabricated SA is employed in the laser experimental setup in ring cavity. The Q-switching regime started at threshold pump power of 103 mW and increasable to 215 mW. The stable pulse train from 41.6 kHz to 76.92 kHz with maximum average output power and pulse energy of 0.17 mW and 3.39 nJ are produced. The shortest pulse width of 1.9 μs is obtained in the proposed experimental work, making it the lowest pulse width ever reported using MWCNTs-based saturable absorber.

Theoretical study on the combined systems of peanut-shaped carbon nanotubes encapsulated in single-walled carbon nanotubes

International Nuclear Information System (INIS)

Wang, Guo; Huang, Yuanhe

2012-01-01

Highlights: ► The combined systems of peanut-shaped carbon nanotubes encapsulated in single-walled carbon nanotubes are investigated. ► The band structures and related electronic properties are calculated by using crystal orbital method. ► The carrier mobility and mean free path are evaluated under the deformation potential theory. -- Abstract: The combined systems of peanut-shaped carbon nanotubes encapsulated in both semiconducting and metallic single-walled carbon nanotubes are investigated by using self-consistent field crystal orbital method based on the density functional theory. The investigation indicates that the interaction between the two constituents is mainly contributed by the π orbitals. The encapsulation does not change the semiconducting or metallic nature of the single-walled carbon nanotubes, but significantly changes the band dispersion and decreases the frontier band width of the metallic one. The carrier mobility and mean free path of the metallic single-walled carbon nanotube increase greatly after the encapsulation. The calculated mobilities have the order of 10 3 cm 2 V −1 s −1 for both of the semiconducting and metallic double-walled carbon nanotubes.

Surface plasmon observed for carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Bursill, L A; Stadelmann, P A [Ecole Polytechnique Federale, Lausanne (Switzerland); Peng, J L; Prawer, S [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1994-12-31

This paper presents parallel electron energy loss spectra (PEELS) results, obtained for individual carbon nanotubes, using nanoprobe techniques (1-2 nm diameter electron beam), energy resolution 0.5 eV and collection times of 4-25 sec. The aim was to use a nanoprobe to compare PEELS spectra from different parts of a tube, in order to search for variations in sp{sup 2}/sp{sup 3} bonding ratios as well as to look for orientation dependent plasmon and core-loss phenomena. It also seemed interesting to compare results for nanotubes with those for other varieties of graphitized carbons. The most interesting result so far was the appearance of a 15 eV plasmon peak, which appeared only for tubes containing {<=} about 12 graphite-like layers. This peak did not shift significantly with tube size. A low-loss peaks at 6 eV of variable relative intensity was also observed this peak was relatively very weak for amorphous tubes; it appears to be characteristic of graphite-like layers, as found for nanotubes and, of course, graphite itself. This paper is restricted to discussion of the low-loss results. The experimental techniques are first described, including some details of the methods which may be used to disperse and support sooty carbons for high-resolution transmission electron microscopy. The results are then presented, followed by an interpretation of all the low-loss PEELS results, including those of the other authors. 14 refs., 2 figs.

Mechanical properties of carbon nanotubes

Science.gov (United States)

Salvetat, J.-P.; Bonard, J.-M.; Thomson, N. H.; Kulik, A. J.; Forró, L.; Benoit, W.; Zuppiroli, L.

A variety of outstanding experimental results on the elucidation of the elastic properties of carbon nanotubes are fast appearing. These are based mainly on the techniques of high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) to determine the Young's moduli of single-wall nanotube bundles and multi-walled nanotubes, prepared by a number of methods. These results are confirming the theoretical predictions that carbon nanotubes have high strength plus extraordinary flexibility and resilience. As well as summarising the most notable achievements of theory and experiment in the last few years, this paper explains the properties of nanotubes in the wider context of materials science and highlights the contribution of our research group in this rapidly expanding field. A deeper understanding of the relationship between the structural order of the nanotubes and their mechanical properties will be necessary for the development of carbon-nanotube-based composites. Our research to date illustrates a qualitative relationship between the Young's modulus of a nanotube and the amount of disorder in the atomic structure of the walls. Other exciting results indicate that composites will benefit from the exceptional mechanical properties of carbon nanotubes, but that the major outstanding problem of load transfer efficiency must be overcome before suitable engineering materials can be produced.

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.

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.

The effect of different temperature profiles upon the length and crystallinity of vertically-aligned multi-walled carbon nanotubes.

Science.gov (United States)

Yun, Jongju; Lee, Cheesung; Zheng, Qing; Baik, Seunghyun

2012-08-01

We synthesized vertically-aligned multi-walled carbon nanotubes with an inner diameter of 1.6-7.5 nm and stack height of 80-28600 microm by chemical vapor deposition. The effects of synthesis conditions such as substrate position in the tube furnace, maximum temperature, temperature increasing rate and synthesis duration on the structure of nanotubes were investigated. It was found that slightly faster temperature increase rate resulted in significantly longer length, larger diameter and more defects of nanotubes. Structural parameters such as inner, outer diameters, wall thickness and defects were investigated using transmission electron microscopy and Raman spectroscopy.

Synthesis of carbon nanotube-TiO2 nanotubular material for reversible hydrogen storage

International Nuclear Information System (INIS)

Mishra, Amrita; Banerjee, Subarna; Mohapatra, Susanta K; Graeve, Olivia A; Misra, Mano

2008-01-01

A material consisting of multi-walled carbon nanotubes (MWCNTs) and larger titania (TiO 2 ) nanotube arrays has been produced and found to be efficient for reversible hydrogen (H 2 ) storage. The TiO 2 nanotube arrays (diameter ∼60 nm and length ∼2-3 μm) are grown on a Ti substrate, and MWCNTs a few μm in length and ∼30-60 nm in diameter are grown inside these TiO 2 nanotubes using chemical vapor deposition with cobalt as a catalyst. The resulting material has been used in H 2 storage experiments based on a volumetric method using the pressure, composition, and temperature relationship of the storage media. This material can store up to 2.5 wt% of H 2 at 77 K under 25 bar with more than 90% reversibility.

Synthesis of carbon nanotube-TiO(2) nanotubular material for reversible hydrogen storage.

Science.gov (United States)

Mishra, Amrita; Banerjee, Subarna; Mohapatra, Susanta K; Graeve, Olivia A; Misra, Mano

2008-11-05

A material consisting of multi-walled carbon nanotubes (MWCNTs) and larger titania (TiO(2)) nanotube arrays has been produced and found to be efficient for reversible hydrogen (H(2)) storage. The TiO(2) nanotube arrays (diameter ∼60 nm and length ∼2-3 µm) are grown on a Ti substrate, and MWCNTs a few µm in length and ∼30-60 nm in diameter are grown inside these TiO(2) nanotubes using chemical vapor deposition with cobalt as a catalyst. The resulting material has been used in H(2) storage experiments based on a volumetric method using the pressure, composition, and temperature relationship of the storage media. This material can store up to 2.5 wt% of H(2) at 77 K under 25 bar with more than 90% reversibility.

Method for nano-pumping using carbon nanotubes

Science.gov (United States)

Insepov, Zeke [Darien, IL; Hassanein, Ahmed [Bolingbrook, IL

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.

Carbon nanotubes for biological and biomedical applications

International Nuclear Information System (INIS)

Yang Wenrong; Thordarson, Pall; Gooding, J Justin; Ringer, Simon P; Braet, Filip

2007-01-01

Ever since the discovery of carbon nanotubes, researchers have been exploring their potential in biological and biomedical applications. The recent expansion and availability of chemical modification and bio-functionalization methods have made it possible to generate a new class of bioactive carbon nanotubes which are conjugated with proteins, carbohydrates, or nucleic acids. The modification of a carbon nanotube on a molecular level using biological molecules is essentially an example of the 'bottom-up' fabrication principle of bionanotechnology. The availability of these biomodified carbon nanotube constructs opens up an entire new and exciting research direction in the field of chemical biology, finally aiming to target and to alter the cell's behaviour at the subcellular or molecular level. This review covers the latest advances of bio-functionalized carbon nanotubes with an emphasis on the development of functional biological nano-interfaces. Topics that are discussed herewith include methods for biomodification of carbon nanotubes, the development of hybrid systems of carbon nanotubes and biomolecules for bioelectronics, and carbon nanotubes as transporters for a specific delivery of peptides and/or genetic material to cells. All of these current research topics aim at translating these biotechnology modified nanotubes into potential novel therapeutic approaches. (topical review)

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.

Carbon nanotube transistors scaled to a 40-nanometer footprint.

Science.gov (United States)

Cao, Qing; Tersoff, Jerry; Farmer, Damon B; Zhu, Yu; Han, Shu-Jen

2017-06-30

The International Technology Roadmap for Semiconductors challenges the device research community to reduce the transistor footprint containing all components to 40 nanometers within the next decade. We report on a p-channel transistor scaled to such an extremely small dimension. Built on one semiconducting carbon nanotube, it occupies less than half the space of leading silicon technologies, while delivering a significantly higher pitch-normalized current density-above 0.9 milliampere per micrometer at a low supply voltage of 0.5 volts with a subthreshold swing of 85 millivolts per decade. Furthermore, we show transistors with the same small footprint built on actual high-density arrays of such nanotubes that deliver higher current than that of the best-competing silicon devices under the same overdrive, without any normalization. We achieve this using low-resistance end-bonded contacts, a high-purity semiconducting carbon nanotube source, and self-assembly to pack nanotubes into full surface-coverage aligned arrays. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

1/f noise in carbon nanotubes

International Nuclear Information System (INIS)

Collins, Philip G.; Fuhrer, M. S.; Zettl, A.

2000-01-01

The electrical noise characteristics of single-walled carbon nanotubes have been investigated. For all three cases of individual isolated nanotubes, thin films of interconnected nanotubes, and bulk nanotube mats, anomalously large bias-dependent 1/f noise is found. The noise magnitude greatly exceeds that commonly observed in metal films, carbon resistors, or even carbon fibers with comparable resistances. A single empirical expression describes the noise for all nanotube samples, suggesting a common noise-generating mechanism proportional only to the number of nanotubes in the conductor. We consider likely sources of the fluctuations, and consequences for electronic applications of nanotubes if the excessive noise cannot be suppressed. (c) 2000 American Institute of Physics

Modelling of single walled carbon nanotube cylindrical structures with finite element method simulations

Science.gov (United States)

Günay, E.

2016-04-01

In this study, the modulus of elasticity and shear modulus values of single-walled carbon nanotubes SWCNTs were modelled by using both finite element method and the Matlab code. Initially, cylindrical armchair and zigzag single walled 3D space frames were demonstrated as carbon nanostructures. Thereafter, macro programs were written by the Matlab code producing the space truss for zigzag and armchair models. 3D space frames were introduced to the ANSYS software and then tension, compression and additionally torsion tests were performed on zigzag and armchair carbon nanotubes with BEAM4 element in obtaining the exact values of elastic and shear modulus values. In this study, two different boundary conditions were tested and especially used in torsion loading. The equivalent shear modulus data was found by averaging the corresponding values obtained from ten different nodal points on the nanotube path. Finally, in this study it was determined that the elastic constant values showed proportional changes by increasing the carbon nanotube diameters up to a certain level but beyond this level these values remained stable.

Modelling of single walled carbon nanotube cylindrical structures with finite element method simulations

International Nuclear Information System (INIS)

Günay, E.

2016-01-01

In this study, the modulus of elasticity and shear modulus values of single-walled carbon nanotubes SWCNTs were modelled by using both finite element method and the Matlab code. Initially, cylindrical armchair and zigzag single walled 3D space frames were demonstrated as carbon nanostructures. Thereafter, macro programs were written by the Matlab code producing the space truss for zigzag and armchair models. 3D space frames were introduced to the ANSYS software and then tension, compression and additionally torsion tests were performed on zigzag and armchair carbon nanotubes with BEAM4 element in obtaining the exact values of elastic and shear modulus values. In this study, two different boundary conditions were tested and especially used in torsion loading. The equivalent shear modulus data was found by averaging the corresponding values obtained from ten different nodal points on the nanotube path. Finally, in this study it was determined that the elastic constant values showed proportional changes by increasing the carbon nanotube diameters up to a certain level but beyond this level these values remained stable.

Modelling of single walled carbon nanotube cylindrical structures with finite element method simulations

Energy Technology Data Exchange (ETDEWEB)

Günay, E. [Gazi University, Mechanical Engineering Department, 06570, Ankara (Turkey)

2016-04-21

In this study, the modulus of elasticity and shear modulus values of single-walled carbon nanotubes SWCNTs were modelled by using both finite element method and the Matlab code. Initially, cylindrical armchair and zigzag single walled 3D space frames were demonstrated as carbon nanostructures. Thereafter, macro programs were written by the Matlab code producing the space truss for zigzag and armchair models. 3D space frames were introduced to the ANSYS software and then tension, compression and additionally torsion tests were performed on zigzag and armchair carbon nanotubes with BEAM4 element in obtaining the exact values of elastic and shear modulus values. In this study, two different boundary conditions were tested and especially used in torsion loading. The equivalent shear modulus data was found by averaging the corresponding values obtained from ten different nodal points on the nanotube path. Finally, in this study it was determined that the elastic constant values showed proportional changes by increasing the carbon nanotube diameters up to a certain level but beyond this level these values remained stable.

Channeling of protons in various types of radially compressed carbon nanotubes

International Nuclear Information System (INIS)

Karabarbounis, A.; Sarros, S.; Trikalinos, Ch.

2015-01-01

Channeling of 10 MeV protons in various types of radially compressed chiral carbon nanotubes is considered. Monte Carlo simulation program is used for the calculation of the trajectories, energy losses and angular distributions of protons in nanotubes of various lengths, where the potential in Doyle–Turner approximation is used to describe the interaction between a proton and a nanotube. Carbon nanotubes, which are considered, are radially compressed at the centre or at both ends. The results show that in some cases a decreased angular distribution of the beam is observed, compared with propagation through a straight nanotube. Furthermore, the energy distribution of channeled protons in nanotubes present a series of small peaks besides a main one, the number of which depends on the nanotube length and the angle of incidence, which in some cases are significantly high

Channeling of protons in various types of radially compressed carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Karabarbounis, A. [Department of Physics, Section of Nuclear and Particle Physics, University of Athens, Panepistimioupolis, Ilissia, 15771 Athens (Greece); Sarros, S., E-mail: stsarros@phys.uoa.gr [Department of Physics, Section of Nuclear and Particle Physics, University of Athens, Panepistimioupolis, Ilissia, 15771 Athens (Greece); Trikalinos, Ch. [Department of Philosophy and History of Science, University of Athens, Panepistimioupolis, Ilissia, 15771 Athens (Greece)

2015-07-15

Channeling of 10 MeV protons in various types of radially compressed chiral carbon nanotubes is considered. Monte Carlo simulation program is used for the calculation of the trajectories, energy losses and angular distributions of protons in nanotubes of various lengths, where the potential in Doyle–Turner approximation is used to describe the interaction between a proton and a nanotube. Carbon nanotubes, which are considered, are radially compressed at the centre or at both ends. The results show that in some cases a decreased angular distribution of the beam is observed, compared with propagation through a straight nanotube. Furthermore, the energy distribution of channeled protons in nanotubes present a series of small peaks besides a main one, the number of which depends on the nanotube length and the angle of incidence, which in some cases are significantly high.

Vertically aligned multiwalled carbon nanotubes as electronic interconnects

Science.gov (United States)

Gopee, Vimal Chandra

The drive for miniaturisation of electronic circuits provides new materials challenges for the electronics industry. Indeed, the continued downscaling of transistor dimensions, described by Moore’s Law, has led to a race to find suitable replacements for current interconnect materials to replace copper. Carbon nanotubes have been studied as a suitable replacement for copper due to its superior electrical, thermal and mechanical properties. One of the advantages of using carbon nanotubes is their high current carrying capacity which has been demonstrated to be three orders of magnitude greater than that of copper. Most approaches in the implementation of carbon nanotubes have so far focused on the growth in vias which limits their application. In this work, a process is described for the transfer of carbon nanotubes to substrates allowing their use for more varied applications. Arrays of vertically aligned multiwalled carbon nanotubes were synthesised by photo-thermal chemical vapour deposition with high growth rates. Raman spectroscopy was used to show that the synthesised carbon nanotubes were of high quality. The carbon nanotubes were exposed to an oxygen plasma and the nature of the functional groups present was determined using X-ray photoelectron spectroscopy. Functional groups, such as carboxyl, carbonyl and hydroxyl groups, were found to be present on the surface of the multiwalled carbon nanotubes after the functionalisation process. The multiwalled carbon nanotubes were metallised after the functionalisation process using magnetron sputtering. Two materials, solder and sintered silver, were chosen to bind carbon nanotubes to substrates so as to enable their transfer and also to make electrical contact. The wettability of solder to carbon nanotubes was investigated and it was demonstrated that both functionalisation and metallisation were required in order for solder to bond with the carbon nanotubes. Similarly, functionalisation followed by metallisation

Utilization of bio-degradable fermented tapioca to synthesized low toxicity of carbon nanotubes for drug delivery applications

Energy Technology Data Exchange (ETDEWEB)

Nurulhuda, I., E-mail: nurulnye@gmail.com [NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Poh, R. [Department of Molecular Medicine, University of Malaya, 50603 Kuala Lumpur (Malaysia); Mazatulikhma, M. Z. [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-Electronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Salman, A. H. A.; Haseeb, A. K.

2016-07-06

Carbon nanotubes (CNT) have potential biomedical applications, and investigations are shifting towards the production of such nanotubes using renewable natural sources. CNTs were synthesized at various temperatures of 700, 750, 800, 850 and 900 °C, respectively, using a local fermented food known as “tapai ubi” or fermented tapioca as a precursor. The liquid part of this fermented food was heated separately at 80°C and channeled directly into the furnace system that employs the thermal chemical vapor deposition (CVD) method. Ferrocene, which was the catalyst was placed in furnace 1 in the thermal CVD process. The resulting CNTs produced from the process were studied using field emission scanning electron microscopy (FESEM) and Raman spectroscopy. The FESEM images showed the growth morphology of the CNTs at the different temperatures employed. It was observed that the higher the synthesis temperature up to a point, the diameter of CNTs produced, after which the diameter increased. CNTs with helical structures were observed at 700 °C with a diameter range of 111 - 143 nm. A more straightened structure was observed at 750 °C with a diameter range of 59 - 121 nm. From 800 °C onwards, the diameters of the CNTs were less than 60 nm. Raman analysis revealed the present of D, G and G’ peak were observed at 1227-1358, 1565-1582, and 2678-2695 cm{sup −1}, respectively. The highest degree of crystallity of the carbon nanotubes synthesized were obtained at 800 °C. The radial breathing mode (RBM) were in range between 212-220 and 279-292 cm{sup −1}. Carbon nanotubes also being functionalized with Polyethylene bis(amine) Mw2000 (PEG 2000-NH2) and showed highly cells viability compared to non-functionalized CNT. The nanotubes synthesized will be applied as drug delivery in future study.

Utilization of bio-degradable fermented tapioca to synthesized low toxicity of carbon nanotubes for drug delivery applications

International Nuclear Information System (INIS)

Nurulhuda, I.; Poh, R.; Mazatulikhma, M. Z.; Rusop, M.; Salman, A. H. A.; Haseeb, A. K.

2016-01-01

Carbon nanotubes (CNT) have potential biomedical applications, and investigations are shifting towards the production of such nanotubes using renewable natural sources. CNTs were synthesized at various temperatures of 700, 750, 800, 850 and 900 °C, respectively, using a local fermented food known as “tapai ubi” or fermented tapioca as a precursor. The liquid part of this fermented food was heated separately at 80°C and channeled directly into the furnace system that employs the thermal chemical vapor deposition (CVD) method. Ferrocene, which was the catalyst was placed in furnace 1 in the thermal CVD process. The resulting CNTs produced from the process were studied using field emission scanning electron microscopy (FESEM) and Raman spectroscopy. The FESEM images showed the growth morphology of the CNTs at the different temperatures employed. It was observed that the higher the synthesis temperature up to a point, the diameter of CNTs produced, after which the diameter increased. CNTs with helical structures were observed at 700 °C with a diameter range of 111 - 143 nm. A more straightened structure was observed at 750 °C with a diameter range of 59 - 121 nm. From 800 °C onwards, the diameters of the CNTs were less than 60 nm. Raman analysis revealed the present of D, G and G’ peak were observed at 1227-1358, 1565-1582, and 2678-2695 cm −1 , respectively. The highest degree of crystallity of the carbon nanotubes synthesized were obtained at 800 °C. The radial breathing mode (RBM) were in range between 212-220 and 279-292 cm −1 . Carbon nanotubes also being functionalized with Polyethylene bis(amine) Mw2000 (PEG 2000-NH2) and showed highly cells viability compared to non-functionalized CNT. The nanotubes synthesized will be applied as drug delivery in future study.

Carbon nanotube plane fastener

Directory of Open Access Journals (Sweden)

Kaori Hirahara

2011-12-01

Full Text Available We report a feature of carbon nanotubes (CNTs that arises when the surfaces of two vertically-aligned CNT brushes are pressed together. Adhesion between the CNTs creates a plane fastener-like device. Observations from scanning electron microscopy and measurements of adhesion properties indicate a device-dependence on CNT density and shape near the tip region. Among other applications, such fasteners have the potential to attach small components onto micron-sized electronic devices.

Vertically aligned carbon nanotube field-effect transistors

KAUST Repository

Li, Jingqi; Zhao, Chao; Wang, Qingxiao; Zhang, Qiang; Wang, Zhihong; Zhang, Xixiang; Abutaha, Anas I.; Alshareef, Husam N.

2012-01-01

Vertically aligned carbon nanotube field-effect transistors (CNTFETs) have been developed using pure semiconducting carbon nanotubes. The source and drain were vertically stacked, separated by a dielectric, and the carbon nanotubes were placed

Sculpting carbon bonds for allotropic transformation through solid-state re-engineering of –sp2 carbon

Energy Technology Data Exchange (ETDEWEB)

Jung, Hyun Young; Araujo, Paulo T.; Kim, Young Lae; Jung, Sung Mi; Jia, Xiaoting; Hong, Sanghyun; Ahn, Chi Won; Kong, Jing; Dresselhaus, Mildred S.; Kar, Swastik; Jung, Yung Joon

2014-09-15

Carbon forms one of nature’s strongest chemical bonds; its allotropes having provided some of the most exciting scientific discoveries in recent times. The possibility of inter-allotropic transformations/hybridization of carbon is hence a topic of immense fundamental and technological interest. Such modifications usually require extreme conditions (high temperature, pressure and/or high-energy irradiations), and are usually not well controlled. Here we demonstrate inter-allotropic transformations/hybridizations of specific types that appear uniformly across large-area carbon networks, using moderate alternating voltage pulses. By controlling the pulse magnitude, small-diameter single-walled carbon nanotubes can be transformed predominantly into larger-diameter single-walled carbon nanotubes, multi-walled carbon nanotubes of different morphologies, multi-layered graphene nanoribbons or structures with sp3 bonds. This re-engineering of carbon bonds evolves via a coalescence-induced reconfiguration of sp2 hybridization, terminates with negligible introduction of defects and demonstrates remarkable reproducibility. This reflects a potential step forward for large-scale engineering of nanocarbon allotropes and their junctions.

Controlling electrical percolation in multicomponent carbon nanotube dispersions.

Science.gov (United States)

Kyrylyuk, Andriy V; Hermant, Marie Claire; Schilling, Tanja; Klumperman, Bert; Koning, Cor E; van der Schoot, Paul

2011-04-10

Carbon nanotube reinforced polymeric composites can have favourable electrical properties, which make them useful for applications such as flat-panel displays and photovoltaic devices. However, using aqueous dispersions to fabricate composites with specific physical properties requires that the processing of the nanotube dispersion be understood and controlled while in the liquid phase. Here, using a combination of experiment and theory, we study the electrical percolation of carbon nanotubes introduced into a polymer matrix, and show that the percolation threshold can be substantially lowered by adding small quantities of a conductive polymer latex. Mixing colloidal particles of different sizes and shapes (in this case, spherical latex particles and rod-like nanotubes) introduces competing length scales that can strongly influence the formation of the system-spanning networks that are needed to produce electrically conductive composites. Interplay between the different species in the dispersions leads to synergetic or antagonistic percolation, depending on the ease of charge transport between the various conductive components.

78 FR 41369 - Certain Small Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe From Romania...

Science.gov (United States)

2013-07-10

... Carbon and Alloy Seamless Standard, Line and Pressure Pipe From Romania: Preliminary Results of..., line and pressure pipe (small diameter seamless pipe) from Romania. The period of review (POR) is... and Alloy Seamless Standard, Line and Pressure Pipe from Romania,'' dated concurrently with this...

Investigating interfacial contact configuration and behavior of single-walled carbon nanotube-based nanodevice with atomistic simulations

Energy Technology Data Exchange (ETDEWEB)

Cui, Jianlei, E-mail: cjlxjtu@mail.xjtu.edu.cn; Zhang, Jianwei [Xi’an Jiaotong University, State Key Laboratory for Manufacturing Systems Engineering (China); He, Xiaoqiao, E-mail: bcxqhe@cityu.edu.hk [City University of Hong Kong, Department of Architecture and Civil Engineering (Hong Kong); Mei, Xuesong; Wang, Wenjun [Xi’an Jiaotong University, State Key Laboratory for Manufacturing Systems Engineering (China); Yang, Xinju [Fudan University, State Key Laboratory of Surface Physics and Department of Physics (China); Xie, Hui; Yang, Lijun; Wang, Yang [Harbin Institute of Technology, State Key Laboratory of Robotics and Systems (China)

2017-03-15

Carbon nanotubes (CNTs), including single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), are considered to be the promising candidates for next-generation interconnects with excellent physical and chemical properties ranging from ultrahigh mechanical strength, to electrical properties, to thermal conductivity, to optical properties, etc. To further study the interfacial contact configurations of SWNT-based nanodevice with a 13.56-Å diameter, the corresponding simulations are carried out with the molecular dynamic method. The nanotube collapses dramatically into the surface with the complete collapse on the Au/Ag/graphite electrode surface and slight distortion on the Si/SiO{sub 2} substrate surface, respectively. The related dominant mechanism is studied and explained. Meanwhile, the interfacial contact configuration and behavior, depended on other factors, are also analyzed in this article.

Direct synthesis of nitrogen-containing carbon nanotubes on carbon paper for fuel cell electrode

Science.gov (United States)

Yin, Wong Wai; Daud, Wan Ramli Wan; Mohamad, Abu Bakar; Kadhum, Abdul Amir Hassan; Majlan, Edy Herianto; Shyuan, Loh Kee

2012-06-01

Organic catalyst has recently been identified as the potential substitution for expensive platinum electrocatalyst for fuel cell application. Numerous studies have shown that the nitrogen-containing carbon nanotubes (N-CNT) can be synthesized through spray pyrolysis or floating chemical vapor deposition (CVD) technique using various type of organometallic as precursors. This paper presents the method of synthesis and the initial findings of the growth of N-CNT directly on carbon paper using a modified CVD technique. In this research, nickel (II) phthalocyanines (Ni-Pc) as precursor was dissolved in ethanol solvent, stirred and sonicated to become homogenized. The solution was poured into a bubbler and heated up to allow the mixture to vaporize. Subsequently, the solution vapor was flowed into the tubical reactor maintained at 900°C. Carbon paper sputtered with nickel nanoparticles was used as the substrate. The synthesized sample was examined through Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM) and Fourier Transform Infra-Red (FTIR). Long, entangled and compartmentalized nanotubes with tube diameter ranging 23-27 nm were found covered the carbon paper surface with approximate of 5.5-6.0 μm in thickness. EDX analysis has successfully showed the presence of nitrogen in the carbon nanotube. FTIR analysis showed the presence of the C-N bond on CNT.

Torsional properties of hexagonal boron nitride nanotubes, carbon nanotubes and their hybrid structures: A molecular dynamics study

Energy Technology Data Exchange (ETDEWEB)

Xiong, Qi-lin, E-mail: xiongql@hust.edu.cn [Department of Mechanics, Huazhong University of Science & Technology, 1037 Luoyu Road, Wuhan 430074 (China); Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment, Luoyu Road 1037, Wuhan 430074 (China); Tian, Xiao Geng [State Key Laboratory for Mechanical Structure Strength and Vibration, Xi’an Jiaotong University, Xi’an 710049 (China)

2015-10-15

The torsional mechanical properties of hexagonal single-walled boron nitride nanotubes (SWBNNTs), single-walled carbon nanotubes (SWCNTs), and their hybrid structures (SWBN-CNTs) are investigated using molecular dynamics (MD) simulation. Two approaches - force approach and energy approach, are adopted to calculate the shear moduli of SWBNNTs and SWCNTs, the discrepancy between two approaches is analyzed. The results show that the shear moduli of single-walled nanotubes (SWNTs), including SWBNNTs and SWCNTs are dependent on the diameter, especially for armchair SWNTs. The armchair SWNTs show the better ability of resistance the twisting comparable to the zigzag SWNTs. The effects of diameter and length on the critical values of torque of SWNTs are obtained by comparing the torsional behaviors of SWNTs with different diameters and different lengths. It is observed that the MD results of the effect of diameter and length on the critical values of torque agrees well with the prediction of continuum shell model. The shear modulus of SWBN-CNT has a significant dependence on the percentages of SWCNT and the hybrid style has also an influence on shear modulus. The critical values of torque of SWBN-CNTs increase with the increase of the percentages of SWCNT. This phenomenon can be interpreted by the function relationship between the torque of different bonds (B-N-X, C-C-X, C-B-X, C-N-X) and the angles of bonds.

Theoretical properties of carbon nanotubes

International Nuclear Information System (INIS)

Palser, A.H.

2000-01-01

Carbon nanotubes are invariably terminated with hemi-fullerene caps. In order to investigate the effect of these caps on the electronic structure, a method is developed to enumerate every hemi-fullerene cap which is commensurate with a given nanotube body. This algorithm is then applied to nanotubes for which I + m ≤ 25. The results of this algorithm are then used to study the effects of caps with different symmetries on the electronic structure of metallic and semi-conducting nanotubes within the Hueckel model. It is found that caps can cause localised and resonance states, although the likelihood of localised states occurring in capped metallic nanotubes is shown to be small. In addition, caps induce a non-uniform charge distribution, in which negative charge tends to accumulate on pentagon vertices. The thesis ends by describing two new density matrix methods for performing linear-scaling electronic-structure calculations within the independent electron approximation. Example calculations demonstrate that these methods provide efficient and robust ways of performing linear-scaling calculations, either grand canonically (at a fixed chemical potential) or canonically (at a fixed electron count). (author)

Structural properties of water around uncharged and charged carbon nanotubes

International Nuclear Information System (INIS)

Dezfoli, Amir Reza Ansari; Mehrabian, Mozaffar Ali; Rafsanjani, Hassan Hashemipour

2013-01-01

Studying the structural properties of water molecules around the carbon nanotubes is very important in a wide variety of carbon nanotubes applications. We studied the number of hydrogen bonds, oxygen and hydrogen density distributions, and water orientation around carbon nanotubes. The water density distribution for all carbon nanotubes was observed to have the same feature. In water-carbon nanotubes interface, a high-density region of water molecules exists around carbon nanotubes. The results reveal that the water orientation around carbon nanotubes is roughly dependent on carbon nanotubes surface charge. The water molecules in close distances to carbon nanotubes were found to make an HOH plane nearly perpendicular to the water-carbon nanotubes interface for carbon nanotubes with negative surface charge. For uncharged carbon nanotubes and carbon nanotubes with positive surface charge, the HOH plane was in tangential orientation with water-carbon nanotubes interface. There was also a significant reduction in hydrogen bond of water region around carbon nanotubes as compared with hydrogen bond in bulk water. This reduction was very obvious for carbon nanotubes with positive surface charge. In addition, the calculation of dynamic properties of water molecules in water-CNT interface revealed that there is a direct relation between the number of Hbonds and self-diffusion coefficient of water molecules

Continuous approximation for interaction energy of adamantane encapsulated inside carbon nanotubes

Science.gov (United States)

Baowan, Duangkamon; Hill, James M.; Bacsa, Wolfgang

2018-02-01

The interaction energy for two adjacent adamantane molecules and that of adamantane molecules encapsulated inside carbon nanotubes are investigated considering only dipole-dipole induced interaction. The Lennard-Jones potential and the continuous approximation are utilised to derive analytical expressions for these interaction energies. The equilibrium distance 3.281 Å between two adamantane molecules is determined. The smallest carbon nanotube radius b0 that can encapsulate the adamantane molecule and the radius of the tube bmax that gives the maximum suction energy, linearly depend on the adamantane radius, are calculated. For larger diameter tubes, the off axis position has been calculated, and equilibrium distance between molecule and tube wall is found to be close to the interlayer spacing in graphene.

Influence of filler alignment in the mechanical and electrical properties of carbon nanotubes/epoxy nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Felisberto, M. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); INQUIMAE-CONICET-UBA, Pab II Ciudad Universitaria, Buenos Aires 1428 (Argentina); Arias-Duran, A. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Ramos, J.A.; Mondragon, I. [Dep. Ingenieria Quimica y M. Ambiente. Esc. Politecnica. UPV/EHU, Pza. Europa 1, Donostia-San Sebastian 20018 (Spain); Candal, R. [INQUIMAE-CONICET-UBA, Pab II Ciudad Universitaria, Buenos Aires 1428 (Argentina); Escuela de Ciencia y Tecnologia-UNSAM, San Martin, Prov. De Buenos Aires (Argentina); Goyanes, S. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Rubiolo, G.H., E-mail: rubiolo@cnea.gov.ar [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Dep. Materiales, Comision Nacional de Energia Atomica (CNEA-CAC), Avda Gral Paz 1499, B1650KNA San Martin (Argentina)

2012-08-15

In this work, we report the mechanical and electrical properties of carbon nanotubes/epoxy composites prepared with aligned and randomly oriented nanotubes as filler. The samples are disks of 30 mm in diameter and 3 mm in thickness. To obtain the carbon nanotubes alignment, an external electric field (250 VAC; 50 Hz) was applied through the thickness of the sample during all the cure process. The AC electrical current was measured, during the cure, as a strategy to determine the optimum time in which the alignment reaches the maximum value. DC conductivity measured after the cure shows a percolation threshold in the filler content one order of magnitude smaller for composites with aligned nanotubes than for composites with randomly oriented filler (from 0.06 to 0.5 wt%). In the percolation threshold, the achieved conductivity was 1.4 Multiplication-Sign 10{sup -5} Sm{sup -1}. In both cases, aligned and randomly distributed carbon nanotube composites, the wear resistance increases with the addition of the filler while the Rockwell hardness decreases independently of the nanotubes alignment.

Low-frequency plasmons in metallic carbon nanotubes

International Nuclear Information System (INIS)

Lin, M.F.; Chuu, D.S.; Shung, K.W.

1997-01-01

A metallic carbon nanotube could exhibit a low-frequency plasmon, while a semiconducting carbon nanotube or a graphite layer could not. This plasmon is due to the free carriers in the linear subbands intersecting at the Fermi level. The low-frequency plasmon, which corresponds to the vanishing transferred angular momentum, belongs to an acoustic plasmon. For a smaller metallic nanotube, it could exist at larger transferred momenta, and its frequency is higher. Such a plasmon behaves as that in a one-dimensional electron gas (EGS). However, it is very different from the π plasmons in all carbon nanotubes. Intertube Coulomb interactions in a metallic multishell nanotube and a metallic nanotube bundle have been included. They have a strong effect on the low-frequency plasmon. The intertube coupling among coaxial nanotubes markedly modifies the acoustic plasmons in separate metallic nanotubes. When metallic carbon nanotubes are packed in the bundle form, the low-frequency plasmon would change into an optical plasmon, and behave like that in a three-dimensional EGS. Experimental measurements could be used to distinguish metallic and semiconducting carbon nanotubes. copyright 1997 The American Physical Society

Packing C60 in Boron Nitride Nanotubes

Science.gov (United States)

Mickelson, W.; Aloni, S.; Han, Wei-Qiang; Cumings, John; Zettl, A.

2003-04-01

We have created insulated C60 nanowire by packing C60 molecules into the interior of insulating boron nitride nanotubes (BNNTs). For small-diameter BNNTs, the wire consists of a linear chain of C60 molecules. With increasing BNNT inner diameter, unusual C60 stacking configurations are obtained (including helical, hollow core, and incommensurate) that are unknown for bulk or thin-film forms of C60. C60 in BNNTs thus presents a model system for studying the properties of dimensionally constrained ``silo'' crystal structures. For the linear-chain case, we have fused the C60 molecules to form a single-walled carbon nanotube inside the insulating BNNT.

Optical properties of spray coated layers with carbon nanotubes and graphene nanoplatelets

Science.gov (United States)

Lorenc, Zofia; Krzeminski, Jakub; Wroblewski, Grzegorz; Salbut, Leszek

2016-04-01

Carbon nanotubes as well as graphene are allotropic forms of carbon. Graphene is a two dimensional (2D) form of atomic-scale, hexagonal lattice, while carbon nanotube is a cylindrical nanostructure composed of a rolled sheet of graphene lattice at specific and discrete angles. Both of discussed materials have a high potential for modern engineering, especially in organic and printed electronics. High transparency in the visible part of the electromagnetic spectrum and low electrical resistance are desirable features in various applications and may be fulfilled with studied carbon nanomaterials. They have chances to become an important technological improvement in customers electronic devices by applying them to electrodes production in flexible screens and light sources. Graphene end carbon nanotubes are conceptually similar. However, characteristic properties of these two substances are different. In the article authors present the results of the transmission in visible electromagnetic spectrum characteristics of different samples. This parameter and the resistance of electrodes are tested, analysed and compared. Characteristics of optical transmittance against resistance with the optimal point of that relationship are presented in paper. Moreover, dependency of graphene nanoplatelets agglomerates arrangement against type of nano-fillers is shown. Two groups of tested inks contain graphene nanoplatelets with different fillers diameters. The third group contains carbon nanotubes. Described parameters are important for production process and results of analysis can be used by technologists working with elastic electronics.

Conformational changes of fibrinogen in dispersed carbon nanotubes

Directory of Open Access Journals (Sweden)

Park SJ

2012-08-01

Full Text Available Sung Jean Park,1 Dongwoo Khang21College of Pharmacy, Gachon University, Yeonsu-gu, Incheon, South Korea; 2School of Nano and Advanced Materials Science Engineering and Center for PRC and RIGET, Gyeongsang National University, Jinju, South KoreaAbstract: The conformational changes of plasma protein structures in response to carbon nanotubes are critical for determining the nanotoxicity and blood coagulation effects of carbon nanotubes. In this study, we identified that the functional intensity of carboxyl groups on carbon nanotubes, which correspond to the water dispersity or hydrophilicity of carbon nanotubes, can induce conformational changes in the fibrinogen domains. Also, elevation of carbon nanotube density can alter the secondary structures (ie, helices and beta sheets of fibrinogen. Furthermore, fibrinogen that had been in contact with the nanoparticle material demonstrated a different pattern of heat denaturation compared with free fibrinogen as a result of a variation in hydrophilicity and concentration of carbon nanotubes. Considering the importance of interactions between carbon nanotubes and plasma proteins in the drug delivery system, this study elucidated the correlation between nanoscale physiochemical material properties of carbon nanotubes and associated structural changes in fibrinogen.Keywords: carbon nanotubes, fibrinogen, nanotoxicity, conformational change, denaturation

Spinning Carbon Nanotube Nanothread under a Scanning Electron Microscope

Directory of Open Access Journals (Sweden)

Mark Schulz

2011-08-01

Full Text Available Nanothread with a diameter as small as one hundred nanometers was manufactured under a scanning electron microscope. Made directly from carbon nanotubes, and inheriting their superior electrical and mechanical properties, nanothread may be the world’s smallest man-made fiber. The smallest thread that can be spun using a bench-top spinning machine is about 5 microns in diameter. Nanothread is a new material building block that can be used at the nanoscale or plied to form yarn for applications at the micro and macro scales. Preliminary electrical and mechanical properties of nanothread were measured. The resistivity of nanothread is less than 10−5 Ω∙m. The strength of nanothread is greater than 0.5 GPa. This strength was obtained from measurements using special glue that cures in an electron microscope. The glue weakened the thread, thus further work is needed to obtain more accurate measurements. Nanothread will have broad applications in enabling electrical components, circuits, sensors, and tiny machines. Yarn can be used for various macroscale applications including lightweight antennas, composites, and cables.

Defect- and dopant-controlled carbon nanotubes fabricated by self-assembly of graphene nanoribbons

Institute of Scientific and Technical Information of China (English)

Cun Zhang and Shaohua Chen

2015-01-01

Molecular dynamics simulations showed that a basal carbon nanotube can activate and guide the fabrication of single-walled carbon nanotubes （CNTs） on its internal surface by self-assembly of edge-unpassivated graphene nanoribbons with defects. Furthermore, the distribution of defects on self-assembled CNTs is controllable. The system temperature and defect fraction are two main factors that influence the success of self-assembly. Due to possible joint flaws formed at the boundaries under a relatively high constant temperature, a technique based on increasing the temperature is adopted. Self-assembly is always successful for graphene nanoribbons with relatively small defect fractions, while it will fail in cases with relatively large ones. Similar to the self-assembly of graphene nanoribbons with defects, graphene nanoribbons with different types of dopants can also be self-assembled into carbon nanotubes. The finding provides a possible fabrication technique not only for carbon nanotubes with metallic or semi-con- ductive properties but also for carbon nanotubes with electromagnetic induction characteristics.

Thermal conductivity and thermal rectification in unzipped carbon nanotubes

International Nuclear Information System (INIS)

Ni Xiaoxi; Li Baowen; Zhang Gang

2011-01-01

We study the thermal transport in completely unzipped carbon nanotubes, which are called graphene nanoribbons, partially unzipped carbon nanotubes, which can be seen as carbon-nanotube-graphene-nanoribbon junctions, and carbon nanotubes by using molecular dynamics simulations. It is found that the thermal conductivity of a graphene nanoribbon is much less than that of its perfect carbon nanotube counterparts because of the localized phonon modes at the boundary. A partially unzipped carbon nanotube has the lowest thermal conductivity due to additional localized modes at the junction region. More strikingly, a significant thermal rectification effect is observed in both partially unzipped armchair and zigzag carbon nanotubes. Our results suggest that carbon-nanotube-graphene-nanoribbon junctions can be used in thermal energy control.

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...

PT AND PT/NI "NEEDLE" ELETROCATALYSTS ON CARBON NANOTUBES WITH HIGH ACTIVITY FOR THE ORR

Energy Technology Data Exchange (ETDEWEB)

Colon-Mercado, H.

2011-11-10

Platinum and platinum/nickel alloy electrocatalysts supported on graphitized (gCNT) or nitrogen doped carbon nanotubes (nCNT) are prepared and characterized. Pt deposition onto carbon nanotubes results in Pt 'needle' formations that are 3.5 nm in diameter and {approx}100 nm in length. Subsequent Ni deposition and heat treatment results in PtNi 'needles' with an increased diameter. All Pt and Pt/Ni materials were tested as electrocatalysts for the oxygen reduction reaction (ORR). The Pt and Pt/Ni catalysts showed excellent performance for the ORR, with the heat treated PtNi/gCNT (1.06 mA/cm{sup 2}) and PtNi/nCNT (0.664 mA/cm{sup 2}) showing the highest activity.

Direct growth of carbon nanotubes on hydroxyapatite using MPECVD

International Nuclear Information System (INIS)

Duraia, El-Shazly M.; Hannora, A.; Mansurov, Z.; Beall, Gary W.

2012-01-01

Graphical abstract: Carbon nanotubes have been grown directly on hydroxyapatite by using microwave plasma-enhanced chemical vapor deposition (MPECVD). Highlights: ► CNTs have been successfully grown directly on hydroxyapatite using MPECVD. ► Diameter distribution of the CNTs lies in the range from 30 to 70 nm. ► The HA surface is partially transformed to β-TCP during the deposition. ► Grown CNTs have good quality and I G /I 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 °C. Raman spectroscopy indicates that the CNTs are of high quality and the I G /I 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 β-tricalcium phosphate via dehydroxylation.

Optical Study of Liquid Crystal Doped with Multiwalled Carbon Nanotube

Science.gov (United States)

Gharde, Rita A.; Thakare, Sangeeta Y.

2014-11-01

Liquid crystalline materials have been useful for display devices i.e watches, calculators, automobile dashboards, televisions, multi media projectors etc. as well as in electro tunable lasers, optical fibers and lenses. Carbon nanotube is chosen as the main experimental factor in this study as it has been observed that Carbon Nano Tube influence the existing properties of liquid crystal host and with the doping of CNT can enhance1 the properties of LC. The combination of carbon nanotube (CNT) and liquid crystal (LC) materials show considerable interest in the scientific community due to unique physical properties of CNT in liquid crystal. Dispersion of CNTs in LCs can provide us a cheap, simple, versatile and effective means of controlling nanotube orientation on macroscopic scale with no restrictions on nanotube type. LCs have the long range orientational order rendering them to be anisotropic phases. If CNTs can be well dispersed in LC matrix, they will align with their long axes along the LC director to minimize distortions of the LC director field and the free energy. In this paper, we doped liquid crystal (Cholesteryl Nonanoate) by a small amount of multiwall carbon nanotube 0.05% and 0.1% wt. We found that by adding carbon nanotube to liquid crystals the melting point of the mixture is decreased but TNI is increased. It has been also observed that with incereas in concentration of carbon nanotube into liquid crystal shows conciderable effect on LC. The prepared samples were characterized using various techniques to study structural, thermal and optical properties i.e PMS, FPSS, UV-Vis spectroscopy, FT-IR measurements, and DTA.

Screen-printed electrodes modified with carbon nanotubes or graphene for simultaneous determination of melatonin and serotonin

International Nuclear Information System (INIS)

Gomez, Federico José Vicente; Martín, Aída; Escarpa, Alberto; Silva, María Fernanda

2015-01-01

Single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT) and graphene have been tested as carbon allotropes for the modification of carbon screen-printed electrodes (CSPEs) to simultaneously determine melatonin (MT) and serotonin (5-HT). Two groups of CSPEs, both 4 mm in diameter, were explored: The first includes commercial SWCNT, MWCNT and graphene, the second includes SWCNT, MWCNT, graphene oxide nanoribbons and reduced nanoribbons that were drop casted on the electrodes. The carbon nanomaterials enhanced the electroactive area in the following order: CSPE carbon nanomaterials, in particular of graphene oxide nanoribbons on CSPEs, represents an excellent and disposable tool for sensing the two target molecules in even small sample volumes. Figures of merit for MT and 5-HT include (a) detection limit of 1.1 and 0.4 μM for MT and 5-HT, respectively; (b) an inter-electrode reproducibility with RSD ≤ 8 %; (c) 120 s response time, and (d) recoveries (in case of spiked samples) ranging from 94 to 103 % (with an RSD < 1 %). (author)

Carbon nanotubes as adsorbent of solid-phase extraction and matrix for laser desorption/ionization mass spectrometry.

Science.gov (United States)

Pan, Chensong; Xu, Songyun; Zou, Hanfa; Guo, Zhong; Zhang, Yu; Guo, Baochuan

2005-02-01

A method with carbon nanotubes functioning both as the adsorbent of solid-phase extraction (SPE) and the matrix for matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) to analyze small molecules in solution has been developed. In this method, 10 microL suspensions of carbon nanotubes in 50% (vol/vol) methanol were added to the sample solution to extract analytes onto surface of carbon nanotubes because of their dramatic hydrophobicity. Carbon nanotubes in solution are deposited onto the bottom of tube with centrifugation. After removing the supernatant fluid, carbon nanotubes are suspended again with dispersant and pipetted directly onto the sample target of the MALDI-MS to perform a mass spectrometric analysis. It was demonstrated by analysis of a variety of small molecules that the resolution of peaks and the efficiency of desorption/ionization on the carbon nanotubes are better than those on the activated carbon. It is found that with the addition of glycerol and sucrose to the dispersant, the intensity, the ratio of signal to noise (S/N), and the resolution of peaks for analytes by mass spectrometry increased greatly. Compared with the previously reported method by depositing sample solution onto thin layer of carbon nanotubes, it is observed that the detection limit for analytes can be enhanced about 10 to 100 times due to solid-phase extraction of analytes in solution by carbon nanotubes. An acceptable result of simultaneously quantitative analysis of three analytes in solution has been achieved. The application in determining drugs spiked into urine has also been realized.

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.

Multiporous carbon allotropes transformed from symmetry-matched carbon nanotubes

Directory of Open Access Journals (Sweden)

Yingxiang Cai

2016-06-01

Full Text Available Carbon nanotubes (CNTs with homogeneous diameters have been proven to transform into new carbon allotropes under pressure but no studies on the compression of inhomogeneous CNTs have been reported. In this study, we propose to build new carbon allotropes from the bottom-up by applying pressure on symmetry-matched inhomogeneous CNTs. We find that the (3,0 CNT with point group C3v and the (6,0 CNT with point group C6v form an all sp3 hybridized hexagonal 3060-Carbon crystal, but the (4,0 CNT with point group D4h and the (8,0 CNT with point group D8h polymerize into a sp2+sp3 hybridized tetragonal 4080-Carbon structure. Their thermodynamic, mechanical and dynamic stabilities show that they are potential carbon allotropes to be experimentally synthesized. The multiporous structures, excellently mechanical properties and special electronic structures (semiconductive 3060-Carbon and semimetallic 4080-Carbon imply their many potential applications, such as gases purification, hydrogen storage and lightweight semiconductor devices. In addition, we simulate their feature XRD patterns which are helpful for identifying the two carbon crystals in future experimental studies.

Multiporous carbon allotropes transformed from symmetry-matched carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Cai, Yingxiang, E-mail: yingxiangcai@ncu.edu.cn; Wang, Hao; Xu, Shengliang; Hu, Yujie; Liu, Ning; Xu, Xuechun [Department of Physics, NanChang University, Jiangxi, Nanchang 330031 (China)

2016-06-15

Carbon nanotubes (CNTs) with homogeneous diameters have been proven to transform into new carbon allotropes under pressure but no studies on the compression of inhomogeneous CNTs have been reported. In this study, we propose to build new carbon allotropes from the bottom-up by applying pressure on symmetry-matched inhomogeneous CNTs. We find that the (3,0) CNT with point group C{sub 3v} and the (6,0) CNT with point group C{sub 6v} form an all sp{sup 3} hybridized hexagonal 3060-Carbon crystal, but the (4,0) CNT with point group D{sub 4h} and the (8,0) CNT with point group D{sub 8h} polymerize into a sp{sup 2}+sp{sup 3} hybridized tetragonal 4080-Carbon structure. Their thermodynamic, mechanical and dynamic stabilities show that they are potential carbon allotropes to be experimentally synthesized. The multiporous structures, excellently mechanical properties and special electronic structures (semiconductive 3060-Carbon and semimetallic 4080-Carbon) imply their many potential applications, such as gases purification, hydrogen storage and lightweight semiconductor devices. In addition, we simulate their feature XRD patterns which are helpful for identifying the two carbon crystals in future experimental studies.

The Effect of Small Additions of Carbon Nanotubes on the Mechanical Properties of Epoxy Polymers under Static and Dynamic Loads

Science.gov (United States)

Tarasov, A. E.; Badamshina, E. R.; Anokhin, D. V.; Razorenov, S. V.; Vakorina, G. S.

2018-01-01

The results of measurements of the mechanical characteristics of cured epoxy composites containing small and ultrasmall additions of single-walled carbon nanotubes in the concentration range from 0 to 0.133 wt % under static and dynamic loads are presented. Static measurements of strength characteristics have been carried out under standard test conditions. Measurements of the Hugoniot elastic limit and spall strength were performed under a shock wave loading of the samples at a deformation rate of (0.8-1.5) ß 105 s-1 before the fracture using explosive devices by recording and subsequent analyzing the evolution of the full wave profiles. It has been shown that agglomerates of nanotubes present in the structure of the composites after curing cause a significant scatter of the measured strength parameters, both in the static and in the dynamic test modes. However, the effects of carbon nanotube additions in the studied concentration interval on the physical and mechanical characteristics of the parameters were not revealed for both types of loading.

A modal analysis of carbon nanotube using elastic network model

International Nuclear Information System (INIS)

Kim, Min Hyeok; Seo, Sang Jae; Lim, Byeong Soo; Choi, Jae Boong; Kim, Moon Ki; Liu, Wing Kam

2012-01-01

Although it is widely known that both size and chirality play significant roles in vibration behaviors of single walled carbon nanotubes (SWCNTs), there haven't been yet enough studies specifying the relationship between structure and vibration mode shape of SWCNTs. We have analyzed the chirality and length dependence of SWCNT by using normal mode analysis based elastic network model in which all interatomic interactions of the given SWCNTs structure are represented by a network of linear spring connections. As this method requires relatively short computation time compared to molecular dynamics simulation, we can efficiently analyze vibration behavior of SWCNTs. To ensure the relationship between SWCNT structure and its vibration mode shapes, we simulated more than one hundred SWCNTs having different types of chirality and length. Results indicated that the first two major mode shapes are bending and breathing. The minimum length of nanotube for maintaining the bending mode does not depend on chirality but on its diameter. Our simulations pointed out that there is a critical aspect ratio between diameter and length to determine vibration mode shapes, and it can be empirically formulated as a function of nanotube length and diameter. Therefore, uniformity control is the most important premise in order to utilize vibration features of SWCNTs. It is also expected that the obtained vibration aspect will play an important role in designing nanotube based devices such as resonators and sensors more accurately

Review on properties, dispersion and toxicology of carbon nanotubes

International Nuclear Information System (INIS)

Saeed, K.

2010-01-01

Carbon nanotubes (CNTs) have the most intensely studied nano structures because of their unique properties. There are two types of carbon nanotubes CNTs, single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), prepared by chemical-vapour deposition (CVD), plasma enhanced chemical-vapour deposition, thermal chemical vapour deposition, Vapour phase growth, Arc discharge and Lasser ablation. Both single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) possess high mechanical and electrical conductivity, ultra-light weight, high aspect ratio and have excellent chemical and thermal stabilities. They also possess semi- and metallic-conductive properties depending upon their chirality. This review focuses on progress toward functionalization (not only dispersed nano tube but also dramatically improve their solubility), preparation and purification, composites and the toxicity of the carbon nanotubes (CNTs). The functional groups attached to carbon nanotubes (CNTs) should react with polymers and improve the mechanical properties of the nano composites. Carbon nanotubes (CNTs) has significant application in pharmaceutical field such as drug delivery and nano medicine, but the available literature also suggests that carbon nanotubes (CNTs) may have unusual toxicity and have more adverse effects than the same mass of nano size carbon and quartz. (author)

Curvature dependence of single-walled carbon nanotubes for SO2 adsorption and oxidation

Science.gov (United States)

Chen, Yanqiu; Yin, Shi; Li, Yueli; Cen, Wanglai; Li, Jianjun; Yin, Huaqiang

2017-05-01

Porous carbon-based catalysts showing high catalytic activity for SO2 oxidation to SO3 is often used in flue gas desulfurization. Their catalytic activity has been ascribed in many publications to the microporous structure and the effect of its spatial confinement. First principles method was used to investigate the adsorption and oxidation of SO2 on the inner and outer surface of single-walled carbon nanotubes (SWCNTs) with different diameters. It is interesting to found that there is a direct correlation: the barrier for the oxidation O_SWCNT + SO2 → SO3 + SWCNT monotonically decreases with the increase of SWCNTs' curvature. The oxygen functional located at the inner wall of SWCNTs with small radius is of higher activity for SO2 oxidation, which is extra enhanced by the spatial confinement effects of SWCNTs. These findings can be useful for the development of carbon-based catalysts and provide clues for the optimization and design of porous carbon catalysts.

Highly aligned carbon nanotube arrays fabricated by bias sputtering

International Nuclear Information System (INIS)

Hayashi, Nobuyuki; Honda, Shin-ichi; Tsuji, Keita; Lee, Kuei-Yi; Ikuno, Takashi; Fujimoto, Keiichi; Ohkura, Shigeharu; Katayama, Mitsuhiro; Oura, Kenjiro; Hirao, Takashi

2003-01-01

Vertically aligned carbon nanotube (CNT) arrays have been successfully grown on Si substrates by dc bias sputtering. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the resultant arrays consisted of dense CNTs with diameters of 40-60 nm and lengths of 300-400 nm. The CNTs were found to have a bamboo-like structure at the end of which metallic nanoparticle was formed, indicating tip growth mechanism. The energy enhancement of carbon particles is a key factor for synthesis of CNTs using dc bias sputtering system

Synthesis and characterization of carbon nanotube from coconut shells activated carbon

Science.gov (United States)

Melati, A.; Hidayati, E.

2016-03-01

Carbon nanotubes (CNTs) have been explored in almost every single cancer treatment modality, including drug delivery, lymphatic targeted chemotherapy, photodynamic therapy, and gene therapy. They are considered as one of the most promising nanomaterial with the capability of both detecting the cancerous cells and delivering drugs or small therapeutic molecules to the cells. CNTs have unique physical and chemical properties such as high aspect ratio, ultralight weight, high mechanical strength, high electrical conductivity, and high thermal conductivity. Coconut Shell was researched as active carbon source on 500 - 600°C. These activated carbon was synthesized becomes carbon nanotube and have been proposed as a promising tool for detecting the expression of indicative biological molecules at early stage of cancer. Clinically, biomarkers cancer can be detected by CNT Biosensor. We are using pyrolysis methods combined with CVD process or Wet Chemical Process on 600°C. Our team has successfully obtained high purity, and aligned MWCNT (Multi Wall Nanotube) bundles on synthesis CNT based on coconut shells raw materials. CNTs can be used to cross the mammalian cell membrane by endocytosis or other mechanisms. SEM characterization of these materials have 179 nm bundles on phase 83° and their materials compound known by using FTIR characterization.

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...

Graphene-carbon nanotube hybrid materials and use as electrodes

Science.gov (United States)

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.

Current-voltage characteristics of carbon nanotubes with substitutional nitrogen

DEFF Research Database (Denmark)

Kaun, C.C.; Larade, B.; Mehrez, H.

2002-01-01

unit cell generates a metallic transport behavior. Nonlinear I-V characteristics set in at high bias and a negative differential resistance region is observed for the doped tubes. These behaviors can be well understood from the alignment/mis-alignment of the current carrying bands in the nanotube leads......We report ab initio analysis of current-voltage (I-V) characteristics of carbon nanotubes with nitrogen substitution doping. For zigzag semiconducting tubes, doping with a single N impurity increases current flow and, for small radii tubes, narrows the current gap. Doping a N impurity per nanotube...

Ag-catalysed cutting of multi-walled carbon nanotubes

International Nuclear Information System (INIS)

La Torre, A; Rance, G A; Miners, S A; Lucas, C Herreros; Smith, E F; Giménez-López, M C; Khlobystov, A N; Fay, M W; Brown, P D; Zoberbier, T; Kaiser, U

2016-01-01

In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon–carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes. (paper)

Nitrotyrosine adsorption on carbon nanotube: a density functional theory study

Science.gov (United States)

Majidi, R.; Karami, A. R.

2014-05-01

We have studied the effect of nitrotyrosine on electronic properties of different single-wall carbon nanotubes by density functional theory. Optimal adsorption configurations of nitrotyrosine adsorbed on carbon nanotube have been determined by calculation of adsorption energy. Adsorption energies indicate that nitrotyrosine is chemisorbed on carbon nanotubes. It is found that the nitrotyrosine adsorption modifies the electronic properties of the semiconducting carbon nanotubes significantly and these nanotubes become n-type semiconductors, while the effect of nitrotyrosine on metallic carbon nanotubes is not considerable and these nanotubes remain metallic. Results clarify sensitivity of carbon nanotubes to nitrotyrosine adsorption and suggest the possibility of using carbon nanotubes as biosensor for nitrotyrosine detection.

Strain Dependence of Photoluminescense of Individual Carbon Nanotubes

Science.gov (United States)

Nikolaev, Pavel N.; Leeuw, Tonya K.; Tsyboulski, Dmitri A.; Bachilo, Sergei M.; Weisman, Bruce; Arepalli, Sivaram

2007-01-01

We have investigated strain dependence of photoluminescense (PL) spectra of single wall carbon nanotubes (SWNT). Nanotubes were sparsely dispersed in a thin PMMA film applied to acrylic bar, and strained in both compression and extension by bending this bar in either direction in a homebuilt four-point bending rig. The average surface strain was measured with high accuracy by a resistive strain gage applied on top of the film. The near infrared imaging and spectroscopy were performed on the inverted microscope equipped with high numerical aperture reflective objective lens and InGaAs CCD cameras. PL was excited with a diode laser at either 658, 730 or 785 nm, linearly polarized in the direction of the strain. We were able to measure (n,m) types and orientation of individual nanotubes with respect to strain direction and strain dependence of their PL maxima. It was found that PL peak shifts with respect to the values measured in SDS micelles are a sum of three components. First, a small environmental shift due to difference in the dielectric constant of the surrounding media, that is constant and independent of the nanotube type. Second, shift due to isotropic compression of the film during drying. Third, shifts produced by the uniaxial loading of the film in the experiment. Second and third shifts follow expression based on the first-order expansion of the TB hamiltonian. Their magnitude is proportional to the nanotube chiral angle and strain, and direction is determined by the nanotube quantum number. PL strain dependence measured for a number of various nanotube types allows to estimate TB carbon-carbon transfer integral.

Microstructure and durability of Portland cement-carbon nanotube composites

OpenAIRE

MacLeod, Alastair James Neil

2017-01-01

The incorporation of carbon nanotubes (CNTs), fibres with diameters less than 100 nanometres that exhibit a tensile strength in excess of ten times greater than steel, into Portland cement (OPC) is a relatively novel, yet promising, development for next-generation construction materials exhibiting enhanced strength and ductility, even multifunctionality. When added to Portland cement, creating a Portland cement-CNT nanocomposite material (OPC-CNT), CNTs promote the nucleation of the princi...

Functionalization of carbon nanotubes with silver clusters

International Nuclear Information System (INIS)

Cveticanin, Jelena; Krkljes, Aleksandra; Kacarevic-Popovic, Zorica; Mitric, Miodrag; Rakocevic, Zlatko; Trpkov, Djordje; Neskovic, Olivera

2010-01-01

In this paper, an advanced method of one-step functionalization of single and multi walled carbon nanotubes (SWCNTs and MWCNTs) using γ-irradiation was described. Two synthesis procedures, related with different reduction species, were employed. For the first time, poly(vinyl alcohol) PVA is successfully utilized as a source to reduce silver (Ag) metal ions without having any additional reducing agents to obtain Ag nanoparticles on CNTs. The decoration of carbon nanotubes with Ag nanoparticles takes place through anchoring of (PVA) on nanotube's surface. Optical properties of as-prepared samples and mechanism responsible for the functionalization of carbon nanotubes were investigated using UV-vis and FTIR spectroscopy, respectively. Decorated carbon nanotubes were visualized using microscopic techniques: transmission electron microscopy and scanning tunneling microscopy. Also, the presence of Ag on the nanotubes was confirmed using energy dispersive X-ray spectroscopy. This simple and effective method of making a carbon nanotube type of composites is of interest not only for an application in various areas of technology and biology, but for investigation of the potential of radiation technology for nanoengineering of materials.

A carbon nanotube immunosensor for Salmonella

Science.gov (United States)

Lerner, Mitchell B.; Goldsmith, Brett R.; McMillon, Ronald; Dailey, Jennifer; Pillai, Shreekumar; Singh, Shree R.; Johnson, A. T. Charlie

2011-12-01

Antibody-functionalized carbon nanotube devices have been suggested for use as bacterial detectors for monitoring of food purity in transit from the farm to the kitchen. Here we report progress towards that goal by demonstrating specific detection of Salmonella in complex nutrient broth solutions using nanotube transistors functionalized with covalently-bound anti-Salmonella antibodies. The small size of the active device region makes them compatible with integration in large-scale arrays. We find that the on-state current of the transistor is sensitive specifically to the Salmonella concentration and saturates at low concentration (Salmonella and other bacteria types, with no sign of saturation even at much larger concentrations (108 cfu/ml).

Review of carbon nanotube nanoelectronics and macroelectronics

International Nuclear Information System (INIS)

Che, Yuchi; Chen, Haitian; Gui, Hui; Liu, Jia; Liu, Bilu; Zhou, Chongwu

2014-01-01

Carbon nanotubes have the potential to spur future development in electronics due to their unequalled electrical properties. In this article, we present a review on carbon nanotube-based circuits in terms of their electrical performance in two major directions: nanoelectronics and macroelectronics. In the nanoelectronics direction, we direct our discussion to the performance of aligned carbon nanotubes for digital circuits and circuits designed for radio-frequency applications. In the macroelectronics direction, we focus our attention on the performance of thin films of carbon nanotube random networks in digital circuits, display applications, and printed electronics. In the last part, we discuss the existing challenges and future directions of nanotube-based nano- and microelectronics. (invited review)

Carbon nanotubes significance in Darcy-Forchheimer flow

Science.gov (United States)

Hayat, Tasawar; Rafique, Kiran; Muhammad, Taseer; Alsaedi, Ahmed; Ayub, Muhammad

2018-03-01

The present article examines Darcy-Forchheimer flow of water-based carbon nanotubes. Flow is induced due to a curved stretchable surface. Heat transfer mechanism is analyzed in presence of convective heating process. Xue model of nanofluid is employed to study the characteristics of both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Results for both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) are achieved and compared. Appropriate transformations correspond to strong nonlinear ordinary differential system. Optimal homotopy analysis method (OHAM) is used for the solution development of the resulting system. The contributions of different sundry variables on the velocity and temperature are studied. Further the skin friction coefficient and local Nusselt number are analyzed graphically for both SWCNTs and MWCNTs cases.

Cohesive zone model of carbon nanotube-coated carbon fiber/polyester composites

International Nuclear Information System (INIS)

Agnihotri, Prabhat Kamal; Kar, Kamal K; Basu, Sumit

2012-01-01

It has been previously reported that the average properties of carbon nanotube-coated carbon fiber/polyester multiscale composites critically depend on the length and density of nanotubes on the fiber surface. In this paper the effect of nanotube length and density on the interfacial properties of the carbon nanotube-coated carbon fiber–polymer interface has been studied using shear lag and a cohesive zone model. The latter model incorporates frictional sliding after complete debonding between the fiber and matrix and has been developed to quantify the effect of nanotube coating on various interfacial characterizing parameters. Our numerical results indicate that fibers with an optimal coverage and length of nanotubes significantly increase the interfacial strength and friction between the fiber and polymer. However, they also embrittle the interface compared with bare fibers. (paper)

The reaction of lithium metal vapor with single walled carbon nanotubes of large diameters

Czech Academy of Sciences Publication Activity Database

Kalbáč, Martin; Kavan, Ladislav; Dunsch, L.

2009-01-01

Roč. 246, 11-12 (2009), s. 2428-2431 ISSN 0370-1972 R&D Projects: GA AV ČR IAA400400911; GA AV ČR KAN200100801; GA AV ČR IAA400400804; GA ČR GC203/07/J067; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : lithium * single walled carbon nanotubes * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 1.150, year: 2009

Carbon nanotube based stationary phases for microchip chromatography

DEFF Research Database (Denmark)

Mogensen, Klaus Bo; Kutter, Jörg Peter

2012-01-01

already been demonstrated in more classical formats, for improved separation performance in gas and liquid chromatography, and for unique applications in solid phase extraction. Carbon nanotubes are now also entering the field of microfluidics, where there is a large potential to be able to provide......The objective of this article is to provide an overview and critical evaluation of the use of carbon nanotubes and related carbon-based nanomaterials for microchip chromatography. The unique properties of carbon nanotubes, such as a very high surface area and intriguing adsorptive behaviour, have...... integrated, tailor-made nanotube columns by means of catalytic growth of the nanotubes inside the fluidic channels. An evaluation of the different implementations of carbon nanotubes and related carbon-based nanomaterials for microfluidic chromatography devices is given in terms of separation performance...

Morphology optimization of CCVD-synthesized multiwall carbon nanotubes, using statistical design of experiments

International Nuclear Information System (INIS)

Nourbakhsh, Amirhasan; Ganjipour, Bahram; Zahedifar, Mostafa; Arzi, Ezatollah

2007-01-01

The possibility of optimization of morphological features of multiwall carbon nanotubes (MWCNTs) using the statistical design of experiments (DoE) is investigated. In this study, MWCNTs were synthesized using a catalytic chemical vapour deposition (CCVD) method in a horizontal reactor using acetylene as the carbon source. The effects of six synthesis parameters (synthesis time, synthesis temperature, catalyst mass, reduction time, acetylene flow rate and hydrogen flow rate) on the average diameter and mean rectilinear length (MRL) of carbon nanotubes were examined using fractional-factorial design (FFD) coupled with response surface methodology (RSM). Using a 2 III 6-3 FFD, the main effects of reaction temperature, hydrogen flow rate and chemical reduction time were concluded to be the key factors influencing the diameter and MRL of MWCNTs; then Box-Behnken design (BBD) was exploited to create a response surface from the main factors. The total number of required runs is 26: 8 runs are for FFD parameter screening, 17 runs are for the response surface obtained by the BBD, and the final run is used to confirm the predicted results

Self-assembled ordered carbon-nanotube arrays and membranes.

Energy Technology Data Exchange (ETDEWEB)

Overmyer, Donald L.; Siegal, Michael P.; Yelton, William Graham

2004-11-01

Imagine free-standing flexible membranes with highly-aligned arrays of carbon nanotubes (CNTs) running through their thickness. Perhaps with both ends of the CNTs open for highly controlled nanofiltration? Or CNTs at heights uniformly above a polymer membrane for a flexible array of nanoelectrodes or field-emitters? How about CNT films with incredible amounts of accessible surface area for analyte adsorption? These self-assembled crystalline nanotubes consist of multiple layers of graphene sheets rolled into concentric cylinders. Tube diameters (3-300 nm), inner-bore diameters (2-15 nm), and lengths (nanometers - microns) are controlled to tailor physical, mechanical, and chemical properties. We proposed to explore growth and characterize nanotube arrays to help determine their exciting functionality for Sandia applications. Thermal chemical vapor deposition growth in a furnace nucleates from a metal catalyst. Ordered arrays grow using templates from self-assembled hexagonal arrays of nanopores in anodized-aluminum oxide. Polymeric-binders can mechanically hold the CNTs in place for polishing, lift-off, and membrane formation. The stiffness, electrical and thermal conductivities of CNTs make them ideally suited for a wide-variety of possible applications. Large-area, highly-accessible gas-adsorbing carbon surfaces, superb cold-cathode field-emission, and unique nanoscale geometries can lead to advanced microsensors using analyte adsorption, arrays of functionalized nanoelectrodes for enhanced electrochemical detection of biological/explosive compounds, or mass-ionizers for gas-phase detection. Materials studies involving membrane formation may lead to exciting breakthroughs in nanofiltration/nanochromatography for the separation of chemical and biological agents. With controlled nanofilter sizes, ultrafiltration will be viable to separate and preconcentrate viruses and many strains of bacteria for 'down-stream' analysis.

Synthesis of carbon nanotubes and nanotube forests on copper catalyst

International Nuclear Information System (INIS)

Kruszka, Bartosz; Terzyk, Artur P; Wiśniewski, Marek; Gauden, Piotr A; Szybowicz, Mirosław

2014-01-01

The growth of carbon nanotubes on bulk copper is studied. We show for the first time, that super growth chemical vapor deposition method can be successfully applied for preparation of nanotubes on copper catalyst, and the presence of hydrogen is necessary. Next, different methods of copper surface activation are studied, to improve catalyst efficiency. Among them, applied for the first time for copper catalyst in nanotubes synthesis, sulfuric acid activation is the most promising. Among tested samples the surface modified for 10 min is the most active, causing the growth of vertically aligned carbon nanotube forests. Obtained results have potential importance in application of nanotubes and copper in electronic chips and nanodevices. (paper)

Pressure Dependence of the Radial Breathing Mode of Carbon Nanotubes: The Effect of Fluid Adsorption

Science.gov (United States)

Longhurst, M. J.; Quirke, N.

2007-04-01

The pressure dependence of shifts in the vibrational modes of individual carbon nanotubes is strongly affected by the nature of the pressure transmitting medium as a result of adsorption at the nanotube surface. The adsorbate is treated as an elastic shell which couples with the radial breathing mode (RBM) of the nanotube via van der Waal interactions. Using analytical methods as well as molecular simulation, we observe a low frequency breathing mode for the adsorbed fluid at ˜50cm-1, as well as diameter dependent upshifts in the RBM frequency with pressure, suggesting metallic nanotubes may wet more than semiconducting ones.

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.

Fabrication of nano-electrode arrays of free-standing carbon nanotubes on nano-patterned substrate by imprint method

Energy Technology Data Exchange (ETDEWEB)

Chang, W.S., E-mail: paul@kimm.re.kr [Department of Nano Mechanics, Korea Institute of Machinery and Materials, 104 Sinseongno, Yuseong-gu Daejeon 305-343 (Korea, Republic of); Kim, J.W. [Gyeongbuk Hybrid Technology Institute, 36 Goeyeon-dong, Yeongcheon, Gyeongbuk 770-170 (Korea, Republic of); Choi, D.G. [Department of Nano Mechanics, Korea Institute of Machinery and Materials, 104 Sinseongno, Yuseong-gu Daejeon 305-343 (Korea, Republic of); Han, C.S. [Gyeongbuk Hybrid Technology Institute, 36 Goeyeon-dong, Yeongcheon, Gyeongbuk 770-170 (Korea, Republic of)

2011-01-15

The synthesis of isolated carbon nanotubes with uniform outer diameters and ordered spacing over wafer-scale areas was investigated for fabrication of nano-electrode arrays on silicon wafers for field emission and sensor devices. Multi-walled carbon nanotubes (MWCNTs) were grown on TiN electrode layer with iron catalyst patterned by nano-imprint lithography (NIL), which allows the precise placement of individual CNTs on a substrate. The proposed techniques, including plasma-enhanced chemical vapor deposition (PECVD) and NIL, are simple, inexpensive, and reproducible methods for fabrication of nano-scale devices in large areas. The catalyst patterns were defined by an array of circles with 200 nm in diameter, and variable lengths of pitch. The nano-patterned master and Fe catalyst were observed with good pattern fidelity over a large area by atomic force microscope (AFM) and scanning electron microscopy (SEM). Nano-electrodes of MWCNTs had diameters ranging from 50 nm to 100 nm and lengths of about 300 nm. Field emission tests showed the reducing ignition voltage as the geometry of nanotube arrays was controlled by catalyst patterning. These results showed a wafer-scale approach to the control of the size, pitch, and position of nano-electrodes of nanotubes for various applications including electron field-emission sources, electrochemical probes, functionalized sensor elements, and so on.

Structural studies of carbon nanotubes by powder x-ray diffraction at SPring-8 and KEK PF

CERN Document Server

Maniwa, Y; Fujiwara, A

2003-01-01

Powder X-ray diffraction (XRD) studies on carbon nanotubes (CNTs) using synchrotron radiation are reported. In spite of the observed broad XRD peak profiles of two-dimensional triangular (hexagonal) lattice of single-wall carbon nanotubes (SWNTs), it was shown that useful structural information, such as the tube diameter and its distribution, can be deduced from detailed analysis of the characteristic XRD patterns. In particular, powder-XRD measurements were performed to study the phase transition of encapsulated materials inside SWNTs. In the C sub 7 sub 0 -one dimensional (1D) crystals formed inside SWNTs, importance of one-dimensionality in the C sub 7 sub 0 -molecular dynamics was suggested. It was also shown that water inside SWNTs undergoes a phase transition from liquid to an ice-nanotube structure below -38degC. Conversion process from SWNT to double-wall carbon nanotube (DWNT) was also studied by XRD.

Selective Deposition and Alignment of Single-Walled Carbon Nanotubes Assisted by Dielectrophoresis: From Thin Films to Individual Nanotubes

Science.gov (United States)

Li, Pengfei; Xue, Wei

2010-06-01

Dielectrophoresis has been used in the controlled deposition of single-walled carbon nanotubes (SWNTs) with the focus on the alignment of nanotube thin films and their applications in the last decade. In this paper, we extend the research from the selective deposition of SWNT thin films to the alignment of small nanotube bundles and individual nanotubes. Electrodes with “teeth”-like patterns are fabricated to study the influence of the electrode width on the deposition and alignment of SWNTs. The entire fabrication process is compatible with optical lithography-based techniques. Therefore, the fabrication cost is low, and the resulting devices are inexpensive. A series of SWNT solutions is prepared with concentrations ranging from 0.0125 to 0.2 mg/ml. The alignment of SWNT thin films, small bundles, and individual nanotubes is achieved under the optimized experimental conditions. The electrical properties of these samples are characterized; the linear current-voltage plots prove that the aligned SWNTs are mainly metallic nanotubes. The microscopy inspection of the samples demonstrates that the alignment of small nanotube bundles and individual nanotubes can only be achieved using narrow electrodes and low-concentration solutions. Our investigation shows that it is possible to deposit a controlled amount of SWNTs in desirable locations using dielectrophoresis.

Selective Deposition and Alignment of Single-Walled Carbon Nanotubes Assisted by Dielectrophoresis: From Thin Films to Individual Nanotubes

Directory of Open Access Journals (Sweden)

Li Pengfei

2010-01-01

Full Text Available Abstract Dielectrophoresis has been used in the controlled deposition of single-walled carbon nanotubes (SWNTs with the focus on the alignment of nanotube thin films and their applications in the last decade. In this paper, we extend the research from the selective deposition of SWNT thin films to the alignment of small nanotube bundles and individual nanotubes. Electrodes with “teeth”-like patterns are fabricated to study the influence of the electrode width on the deposition and alignment of SWNTs. The entire fabrication process is compatible with optical lithography-based techniques. Therefore, the fabrication cost is low, and the resulting devices are inexpensive. A series of SWNT solutions is prepared with concentrations ranging from 0.0125 to 0.2 mg/ml. The alignment of SWNT thin films, small bundles, and individual nanotubes is achieved under the optimized experimental conditions. The electrical properties of these samples are characterized; the linear current–voltage plots prove that the aligned SWNTs are mainly metallic nanotubes. The microscopy inspection of the samples demonstrates that the alignment of small nanotube bundles and individual nanotubes can only be achieved using narrow electrodes and low-concentration solutions. Our investigation shows that it is possible to deposit a controlled amount of SWNTs in desirable locations using dielectrophoresis.

Marine fouling release silicone/carbon nanotube nanocomposite coatings: on the importance of the nanotube dispersion state.

Science.gov (United States)

Beigbeder, Alexandre; Mincheva, Rosica; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Claes, Michael; Dubois, Philippe

2010-05-01

The present work reports on the influence of the dispersion quality of multiwall carbon nanotubes (MWCNTs) in a silicone matrix on the marine fouling-release performance of the resulting nanocomposite coatings. A first set of coatings filled with different nanofiller contents was prepared by the dilution of a silicone/MWCNTs masterbatch within a hydrosilylation-curing polydimethylsiloxane resin. The fouling-release properties of the nanocomposite coatings were studied through laboratory assays with the marine alga (seaweed) Ulva, a common fouling species. As reported previously (see Ref. [19]), the addition of a small (0.05%) amount of carbon nanotubes substantially improves the fouling-release properties of the silicone matrix. This paper shows that this improvement is dependent on the amount of filler, with a maximum obtained with 0.1 wt% of multiwall carbon nanotubes (MWCNTs). The method of dispersion of carbon nanotubes in the silicone matrix is also shown to significantly (p = 0.05) influence the fouling-release properties of the coatings. Dispersing 0.1% MWCNTs using the masterbatch approach yielded coatings with circa 40% improved fouling-release properties over those where MWCNTs were dispersed directly in the polymeric matrix. This improvement is directly related to the state of nanofiller dispersion within the cross-linked silicone coating.

Synthesis of high quality single-walled carbon nanotubes via a catalytic layer reinforced by self-assembled monolayers

International Nuclear Information System (INIS)

Adhikari, Prashanta Dhoj; Song, Wooseok; Cha, Myoung-Jun; Park, Chong-Yun

2013-01-01

This work reports the synthesis of high quality single-walled carbon nanotubes (SWCNT) using a catalytic layer reinforced by self-assembled monolayers (SAM). Amine-SAM was introduced on a SiO 2 /Si substrate and then an iron nanoparticles solution was dropped on the substrate by spin-coating. This catalytic template was used to grow carbon nanotubes by chemical vapor deposition and the synthesized SWCNT were observed to be prominent, based on the size distribution. Highly dense SWCNT with a diameter of about 1.1-1.2 nm were produced at 800-850 °C. Moreover, the diameter distribution of the SWCNT was more selective at a growth temperature of 900 °C. These findings provide important insights for a SAM support layer that can play the role as a restriction for the agglomeration of iron catalyst and is promising for the synthesis of high quality SWCNT. - Highlights: • Fe nanoparticles on self-assembled monolayers (SAM) containing template is underlined. • Its catalytic behavior to synthesis single-walled carbon nanotubes is studied. • The role of SAM on catalytic template is explored

Synthesis and Characterization Carbon Nanotubes Doped Carbon Aerogels

Science.gov (United States)

Xu, Yuelong; Yan, Meifang; Liu, Zhenfa

2017-12-01

Polycondensation of phloroglucinol, resorcinol and formaldehyde with carbon nanotube (CNT) as the additives, using sodium carbonate as the catalyst, leads to the formation of CNT - doped carbon aerogels. The structure of carbon aerogels (CAs) with carbon nanotubes (CNTs) were characterized by X-ray diffraction and scanning electron microscopy. The specific surface area, pore size distribution and pore volume were measured by surface area analyzer. The results show that when the optimum doping dosage is 5%, the specific surface area of CNT - doped carbon aerogel is up to 665 m2 g-1 and exhibit plentiful mesoporous.

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....... A model for the dielectrophoretic assembly of carbon nanotubes on microelectrodes was developed and several simulations were conducted using values from the available literature for the various key parameters. The model can give qualitative results regarding the parameters dominating the dielectrophoretic...

Enhancing the electrochemical response of myoglobin with carbon nanotube electrodes.

Science.gov (United States)

Esplandiu, M J; Pacios, M; Cyganek, L; Bartroli, J; del Valle, M

2009-09-02

In this paper, the electrochemical behavior of different myoglobin-modified carbon electrodes is evaluated. In particular, the performance of voltammetric biosensors made of forest-like carbon nanotubes, carbon nanotube composites and graphite composites is compared by monitoring mainly the electrocatalytic reduction of H(2)O(2) by myoglobin and their corresponding electroanalytical characteristics. Graphite composites showed the worst electroanalytical performance, exhibiting a small linear range, a limit of detection (LOD) of 9 x 10(-5) M and low sensitivity. However, it was found that the electrochemical response was enhanced with the use of carbon nanotube-based electrodes with LOD up to 5 x 10(-8) M, higher sensitivities and wider linear range response. On the one hand, in the case of the CNT epoxy composite, the improvement in the response can be mainly attributed to its more porous surface which allows the immobilization of higher amounts of the electroactive protein. On the other hand, in the case of the forest-like CNT electrodes, the enhancement is due to an increase in the electron transfer kinetics. These findings encourage the use of myoglobin-modified carbon nanotube electrodes as potential (bio)sensors of H(2)O(2) or O(2) in biology, microbiology and environmental fields.

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.

Multiscale Hybrid Micro-Nanocomposites Based on Carbon Nanotubes and Carbon Fibers

Directory of Open Access Journals (Sweden)

Fawad Inam

2010-01-01

Full Text Available Amino-modified double wall carbon nanotube (DWCNT-NH2/carbon fiber (CF/epoxy hybrid micro-nanocomposite laminates were prepared by a resin infusion technique. DWCNT-NH2/epoxy nanocomposites and carbon fiber/epoxy microcomposites were made for comparison. Morphological analysis of the hybrid composites was performed using field emission scanning electron microscope. A good dispersion at low loadings of carbon nanotubes (CNTs in epoxy matrix was achieved by a bath ultrasonication method. Mechanical characterization of the hybrid micro-nanocomposites manufactured by a resin infusion process included three-point bending, mode I interlaminar toughness, dynamic mechanical analysis, and drop-weight impact testing. The addition of small amounts of CNTs (0.025, 0.05, and 0.1 wt% to epoxy resins for the fabrication of multiscale carbon fiber composites resulted in a maximum enhancement in flexural modulus by 35%, a 5% improvement in flexural strength, a 6% improvement in absorbed impact energy, and 23% decrease in the mode I interlaminar toughness. Hybridization of carbon fiber-reinforced epoxy using CNTs resulted in a reduction in and dampening characteristics, presumably as a result of the presence of micron-sized agglomerates.

Interaction between fullerene halves C_n (n ≤ 40) and single wall carbon nanotube

International Nuclear Information System (INIS)

Sharma, Amrish; Kaur, Sandeep; Mudahar, Isha

2016-01-01

We have investigated the structural and electronic properties of carbon nanotube with small fullerene halves C_n (n ≤ 40) which are covalently bonded to the side wall of an armchair single wall carbon nanotube (SWCNT) using first principle method based on density functional theory. The fullerene size results in weak bonding between fullerene halves and carbon nanotube (CNT). Further, it was found that the C-C bond distance that attaches the fullerene half and CNT is of the order of 1.60 Å. The calculated binding energies indicate the stability of the complexes formed. The HOMO-LUMO gaps and electron density of state plots points towards the metallicity of the complex formed. Our calculations on charge transfer reveal that very small amount of charge is transferred from CNT to fullerene halves.

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 ...

Dispersions of Carbon nanotubes in Polymer Matrices

Science.gov (United States)

Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

2010-01-01

Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

Synthesis of carbon nanotubes bridging metal electrodes

International Nuclear Information System (INIS)

Kotlar, M.; Vojs, M.; Marton, M.; Vesel, M.; Redhammer, R.

2012-01-01

In our work we demonstrate growth of carbon nanotubes that can conductively bridge the metal electrodes. The role of different catalysts was examined. Interdigitated metal electrodes are made from copper and we are using bimetal Al/Ni as catalyst for growth of carbon nanotubes. We are using this catalyst composition for growth of the single-walled carbon nanotube network. (authors)

Mechanics of single-walled carbon nanotubes inside open single-walled carbon nanocones

International Nuclear Information System (INIS)

Ansari, R.; Hosseinzadeh, M.

2013-01-01

This study investigates the mechanical characteristics of single-walled carbon nanotubes (CNTs) inside open single-walled carbon nanocones (CNCs). New semi-analytical expressions are presented to evaluate van der Waals (vdW) interactions between CNTs and open CNCs. Continuum approximation, along with the the Lennard-Jones (LJ) potential function, is used in this study. The effects of geometrical parameters on alterations in vdW potential energy and the interaction force are extensively examined for the concentric CNT-open CNC configuration. The CNT is assumed to enter the nanocone either through the small end or the wide end of the cone. The preferred position of the CNT with respect to the nanocone axis is fully investigated for various geometrical parameters. The optimum nanotube radius minimizing the total potential energy of the concentric configuration is determined for different radii of the small end of the cone. The examined configuration generates asymmetric oscillation; thus, the system constitutes a nano-oscillator.

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...... the calculated energies we determine the elastic properties of the single-wall carbon nanotubes (Young modulus, curvature constant) and perform a comparison with available experimental measurements and earlier theoretical predictions....

Effect of catalyst preparation on the yield of carbon nanotube growth

International Nuclear Information System (INIS)

Escobar, Mariano; Rubiolo, Gerardo; Candal, Roberto; Goyanes, Silvia

2009-01-01

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.

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.

Growth of carbon nanotubes in arc plasma treated graphite disc: microstructural characterization and electrical conductivity study

Science.gov (United States)

Nayak, B. B.; Sahu, R. K.; Dash, T.; Pradhan, S.

2018-03-01

Circular graphite discs were treated in arc plasma by varying arcing time. Analysis of the plasma treated discs by field emission scanning electron microscope revealed globular grain morphologies on the surfaces, but when the same were observed at higher magnification and higher resolution under transmission electron microscope, growth of multiwall carbon nanotubes of around 2 nm diameter was clearly seen. In situ growth of carbon nanotube bundles/bunches consisting of around 0.7 nm tube diameter was marked in the case of 6 min treated disc surface. Both the untreated and the plasma treated graphite discs were characterized by X-ray diffraction, energy dispersive spectra of X-ray, X-ray photoelectron spectroscopy, transmission electron microscopy, micro Raman spectroscopy and BET surface area measurement. From Raman spectra, BET surface area and microstructure observed in transmission electron microscope, growth of several layers of graphene was identified. Four-point probe measurements for electrical resistivity/conductivity of the graphite discs treated under different plasma conditions showed significant increase in conductivity values over that of untreated graphite conductivity value and the best result, i.e., around eightfold increase in conductivity, was observed in the case of 6 min plasma treated sample exhibiting carbon nanotube bundles/bunches grown on disc surface. By comparing the microstructures of the untreated and plasma treated graphite discs, the electrical conductivity increase in graphite disc is attributed to carbon nanotubes (including bundles/bunches) growth on disc surface by plasma treatment.

Chirality Characterization of Dispersed Single Wall Carbon Nanotubes

Science.gov (United States)

Namkung, Min; Williams, Phillip A.; Mayweather, Candis D.; Wincheski, Buzz; Park, Cheol; Namkung, Juock S.

2005-01-01

Raman scattering and optical absorption spectroscopy are used for the chirality characterization of HiPco single wall carbon nanotubes (SWNTs) dispersed in aqueous solution with the surfactant sodium dodecylbenzene sulfonate. Radial breathing mode (RBM) Raman peaks for semiconducting and metallic SWNTs are identified by directly comparing the Raman spectra with the Kataura plot. The SWNT diameters are calculated from these resonant peak positions. Next, a list of (n, m) pairs, yielding the SWNT diameters within a few percent of that obtained from each resonant peak position, is established. The interband transition energies for the list of SWNT (n, m) pairs are calculated based on the tight binding energy expression for each list of the (n, m) pairs, and the pairs yielding the closest values to the corresponding experimental optical absorption peaks are selected. The results reveal that (1, 11), (4, 11), and (0, 11) as the most probable chiralities of the semiconducting nanotubes. The results also reveal that (4, 16), (6, 12) and (8, 8) are the most probable chiralities for the metallic nanotubes. Directly relating the Raman scattering data to the optical absorption spectra, the present method is considered the simplest technique currently available. Another advantage of this technique is the use of the E(sup 8)(sub 11) peaks in the optical absorption spectrum in the analysis to enhance the accuracy in the results.

Selective Functionalization of Carbon Nanotubes: Part II

Science.gov (United States)

Meyyappan, Meyya; Khare, Bishun

2010-01-01

An alternative method of low-temperature plasma functionalization of carbon nanotubes provides for the simultaneous attachment of molecular groups of multiple (typically two or three) different species or different mixtures of species to carbon nanotubes at different locations within the same apparatus. This method is based on similar principles, and involves the use of mostly the same basic apparatus, as those of the methods described in "Low-Temperature Plasma Functionalization of Carbon Nanotubes" (ARC-14661-1), NASA Tech Briefs, Vol. 28, No. 5 (May 2004), page 45. The figure schematically depicts the basic apparatus used in the aforementioned method, with emphasis on features that distinguish the present alternative method from the other. In this method, one exploits the fact that the composition of the deposition plasma changes as the plasma flows from its source in the precursor chamber toward the nanotubes in the target chamber. As a result, carbon nanotubes mounted in the target chamber at different flow distances (d1, d2, d3 . . .) from the precursor chamber become functionalized with different species or different mixtures of species. In one series of experiments to demonstrate this method, N2 was used as the precursor gas. After the functionalization process, the carbon nanotubes from three different positions in the target chamber were examined by Fourier-transform infrared spectroscopy to identify the molecular groups that had become attached. On carbon nanotubes from d1 = 1 cm, the attached molecular groups were found to be predominantly C-N and C=N. On carbon nanotubes from d2 = 2.5 cm, the attached molecular groups were found to be predominantly C-(NH)2 and/or C=NH2. (The H2 was believed to originate as residual hydrogen present in the nanotubes.) On carbon nanotubes from d3 = 7 cm no functionalization could be detected - perhaps, it was conjectured, because this distance is downstream of the plasma source, all of the free ions and free radicals of

Plasmonic-Resonant Bowtie Antenna for Carbon Nanotube Photodetectors

Directory of Open Access Journals (Sweden)

Hongzhi Chen

2012-01-01

Full Text Available The design of bowtie antennas for carbon nanotube (CNT photodetectors has been investigated. CNT photodetectors have shown outstanding performance by using CNT as sensing element. However, detection wavelength is much larger than the diameter of the CNT, resulting in small fill factor. Bowtie antenna can confine light into a subwavelength volume based on plasmonic resonance, thus integrating a bowtie antenna to CNT photodetectors can highly improve photoresponse of the detectors. The electric field enhancement of bowtie antennas was calculated using the device geometry by considering fabrication difficulties and photodetector structure. It is shown that the electric field intensity enhancement increased exponentially with distance reduction between the CNT photodetector to the antenna. A redshift of the peak resonance wavelength is predicted due to the increase of tip angles of the bowtie antennas. Experimental results showed that photocurrent enhancement agreed well with theoretical calculations. Bowtie antennas may find wide applications in nanoscale photonic sensors.

Quantum oscillations and ferromagnetic hysteresis observed in iron filled multiwall carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Barzola-Quiquia, Jose; Klingner, Niko; Molle, Axel [Division of Superconductivity and Magnetism, University of Leipzig, D-04103 Leipzig (Germany); Leonhardt, Albrecht [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany)

2011-07-01

Carbon-based materials as multiwall carbon nanotubes (MWCNT) are attractive for spintronics because spin is only weakly coupled to the lattice, leading to large spin-flip scattering length and long spin relaxation times. In this contribution we have investigated the electrical transport properties of iron filled MWCNT (outer diameter 150 nm, inner diameter 25 nm and length 2000 nm) as a function of temperature and magnetic field. We observed quantum interference effects, i.e. universal conductance fluctuations, and weak localization effects. The in-plane magnetoresistance shows typical butterfly structure revealing the ferromagnetic properties of the Fe-filled MWCNT. The ferromagnetic hysteresis was observed up to 40K.

Nano-Reinforcement of Interfaces in Prepreg-Based Composites Using a Carbon Nanotubes Spraying Method

KAUST Repository

Almuhammadi, Khaled

2012-01-01

of epoxy resins used as matrix materials for CFRP composites can be increased by the addition of nano-sized fillers such as Carbon nanotubes (CNTs). CNTs are particularly well suited for this purpose because of their nano-scale diameter and high aspect

Geckolike high shear strength by carbon nanotube fiber adhesives

Science.gov (United States)

Maeno, Y.; Nakayama, Y.

2009-01-01

Carbon nanotube adhesives can adhere strongly to surfaces as a gecko does. The number of carbon nanotube layers is an important determinant of the contact area for adhesion. Balancing the catalyst ratio and buffer layer used for chemical vapor deposition processing controls the number of carbon nanotube layers and their distribution. The features of carbon nanotubes determine the shear strength of adhesion. Carbon nanotubes with a broad distribution of layers exhibit enhanced shear strength with equivalent adhesive capability to that of a natural Tokay Gecko (Gekko gecko)

Turning refuse plastic into multi-walled carbon nanotube forest

Directory of Open Access Journals (Sweden)

Eugene Oh, Jaegeun Lee, Seung-Ho Jung, Seungho Cho, Hye-Jin Kim, Sung-Hyun Lee, Kun-Hong Lee, Kyong-Hwa Song, Chi-Hoon Choi and Do Suck Han

2012-01-01

Full Text Available A novel and effective method was devised for synthesizing a vertically aligned carbon nanotube (CNT forest on a substrate using waste plastic obtained from commercially available water bottles. The advantages of the proposed method are the speed of processing and the use of waste as a raw material. A mechanism for the CNT growth was also proposed. The growth rate of the CNT forest was ~2.5 μm min−1. Transmission electron microscopy images indicated that the outer diameters of the CNTs were 20–30 nm on average. The intensity ratio of the G and D Raman bands was 1.27 for the vertically aligned CNT forest. The Raman spectrum showed that the wall graphitization of the CNTs, synthesized via the proposed method was slightly higher than that of commercially available multi-walled carbon nanotubes (MWCNTs. We expect that the proposed method can be easily adapted to the disposal of other refuse materials and applied to MWCNT production industries.

Turning refuse plastic into multi-walled carbon nanotube forest

Science.gov (United States)

Oh, Eugene; Lee, Jaegeun; Jung, Seung-Ho; Cho, Seungho; Kim, Hye-Jin; Lee, Sung-Hyun; Lee, Kun-Hong; Song, Kyong-Hwa; Choi, Chi-Hoon; Han, Do Suck

2012-01-01

A novel and effective method was devised for synthesizing a vertically aligned carbon nanotube (CNT) forest on a substrate using waste plastic obtained from commercially available water bottles. The advantages of the proposed method are the speed of processing and the use of waste as a raw material. A mechanism for the CNT growth was also proposed. The growth rate of the CNT forest was ∼2.5 μm min−1. Transmission electron microscopy images indicated that the outer diameters of the CNTs were 20–30 nm on average. The intensity ratio of the G and D Raman bands was 1.27 for the vertically aligned CNT forest. The Raman spectrum showed that the wall graphitization of the CNTs, synthesized via the proposed method was slightly higher than that of commercially available multi-walled carbon nanotubes (MWCNTs). We expect that the proposed method can be easily adapted to the disposal of other refuse materials and applied to MWCNT production industries. PMID:27877482

Carbon Nanotubes: Applications in Pharmacy and Medicine

Science.gov (United States)

He, Hua; Pham-Huy, Lien Ai; Dramou, Pierre; Xiao, Deli; Zuo, Pengli

2013-01-01

Carbon nanotubes (CNTs) are allotropes of carbon, made of graphite and constructed in cylindrical tubes with nanometer in diameter and several millimeters in length. Their impressive structural, mechanical, and electronic properties are due to their small size and mass, their strong mechanical potency, and their high electrical and thermal conductivity. CNTs have been successfully applied in pharmacy and medicine due to their high surface area that is capable of adsorbing or conjugating with a wide variety of therapeutic and diagnostic agents (drugs, genes, vaccines, antibodies, biosensors, etc.). They have been first proven to be an excellent vehicle for drug delivery directly into cells without metabolism by the body. Then other applications of CNTs have been extensively performed not only for drug and gene therapies but also for tissue regeneration, biosensor diagnosis, enantiomer separation of chiral drugs, extraction and analysis of drugs and pollutants. Moreover, CNTs have been recently revealed as a promising antioxidant. This minireview focuses the applications of CNTs in all fields of pharmacy and medicine from therapeutics to analysis and diagnosis as cited above. It also examines the pharmacokinetics, metabolism and toxicity of different forms of CNTs and discusses the perspectives, the advantages and the obstacles of this promising bionanotechnology in the future. PMID:24195076

Carbon Nanotubes: Applications in Pharmacy and Medicine

Directory of Open Access Journals (Sweden)

Hua He

2013-01-01

Full Text Available Carbon nanotubes (CNTs are allotropes of carbon, made of graphite and constructed in cylindrical tubes with nanometer in diameter and several millimeters in length. Their impressive structural, mechanical, and electronic properties are due to their small size and mass, their strong mechanical potency, and their high electrical and thermal conductivity. CNTs have been successfully applied in pharmacy and medicine due to their high surface area that is capable of adsorbing or conjugating with a wide variety of therapeutic and diagnostic agents (drugs, genes, vaccines, antibodies, biosensors, etc.. They have been first proven to be an excellent vehicle for drug delivery directly into cells without metabolism by the body. Then other applications of CNTs have been extensively performed not only for drug and gene therapies but also for tissue regeneration, biosensor diagnosis, enantiomer separation of chiral drugs, extraction and analysis of drugs and pollutants. Moreover, CNTs have been recently revealed as a promising antioxidant. This minireview focuses the applications of CNTs in all fields of pharmacy and medicine from therapeutics to analysis and diagnosis as cited above. It also examines the pharmacokinetics, metabolism and toxicity of different forms of CNTs and discusses the perspectives, the advantages and the obstacles of this promising bionanotechnology in the future.

Methods for producing reinforced carbon nanotubes

Science.gov (United States)

Ren, Zhifen [Newton, MA; Wen, Jian Guo [Newton, MA; Lao, Jing Y [Chestnut Hill, MA; Li, Wenzhi [Brookline, MA

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.

Aspect ratio has no effect on genotoxicity of multi-wall carbon nanotubes.

Science.gov (United States)

Kim, Jin Sik; Lee, Kyu; Lee, Young Hee; Cho, Hyun Sun; Kim, Ki Heon; Choi, Kyung Hee; Lee, Sang Hee; Song, Kyung Seuk; Kang, Chang Soo; Yu, Il Je

2011-07-01

Carbon nanotubes (CNTs) have specific physico-chemical and electrical properties that are useful for telecommunications, medicine, materials, manufacturing processes and the environmental and energy sectors. Yet, despite their many advantages, it is also important to determine whether CNTs may represent a hazard to the environment and human health. Like asbestos, the aspect ratio (length:diameter) and metal components of CNTs are known to have an effect on the toxicity of carbon nanotubes. Thus, to evaluate the toxic potential of CNTs in relation to their aspect ratio and metal contamination, in vivo and in vitro genotoxicity tests were conducted using high-aspect-ratio (diameter: 10-15 nm, length: ~10 μm) and low-aspect-ratio multi-wall carbon nanotubes (MWCNTs, diameter: 10-15 nm, length: ~150 nm) according to OECD test guidelines 471 (bacterial reverse mutation test), 473 (in vitro chromosome aberration test), and 474 (in vivo micronuclei test) with a good laboratory practice system. To determine the treatment concentration for all the tests, a solubility and dispersive test was performed, and a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) solution found to be more suitable than distilled water. Neither the high- nor the low-aspect-ratio MWCNTs induced any genotoxicity in a bacterial reverse mutation test (~1,000 μg/plate), in vitro chromosome aberration test (without S9: ~6.25 μg/ml, with S9: ~50 μg/ml), or in vivo micronuclei test (~50 mg/kg). However, the high-aspect-ratio MWCNTs were found to be more toxic than the low-aspect-ratio MWCNTs. Thus, while high-aspect-ratio MWCNTs do not induce direct genotoxicity or metabolic activation-mediated genotoxicity, genotoxicity could still be induced indirectly through oxidative stress or inflammation.

Magnetoreresistance of carbon nanotube-polypyrrole composite yarns

Science.gov (United States)

Ghanbari, R.; Ghorbani, S. R.; Arabi, H.; Foroughi, J.

2018-05-01

Three types of samples, carbon nanotube yarn and carbon nanotube-polypyrrole composite yarns had been investigated by measurement of the electrical conductivity as a function of temperature and magnetic field. The conductivity was well explained by 3D Mott variable range hopping (VRH) law at T < 100 K. Both positive and negative magnetoresistance (MR) were observed by increasing magnetic field. The MR data were analyzed based a theoretical model. A quadratic positive and negative MR was observed for three samples. It was found that the localization length decreases with applied magnetic field while the density of states increases. The increasing of the density of states induces increasing the number of available energy states for hopping. Thus the electron hopping probability increases in between sites with the shorter distance that results to small the average hopping length.

Time-resolved laser-induced incandescence from multiwalled carbon nanotubes in air

Energy Technology Data Exchange (ETDEWEB)

Mitrani, J. M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA; Shneider, M. N. [Department of Mechanical Engineering, Princeton University, Princeton, New Jersey 08544, USA

2015-01-26

We observed temporal laser-induced incandescence (LII) signals from multiwalled carbon nanotubes(MWCNTs) suspended in ambient air. Unlike previous LII experiments with soot particles, which showed that primary particles with larger diameters cool at slower timescales relative to smaller particles, we observed that thicker MWCNTs with larger outer diameters (ODs) cool at faster timescales relative to thinner MWCNTs with smaller ODs. We suggested a simple explanation of this effect, based on the solution of one-dimensional nonstationary heat conduction equation for the initial non-uniform heating of MWCNTs with ODs greater than the skin depth.

Universal interaction-driven gap in metallic carbon nanotubes

Science.gov (United States)

Senger, Mitchell J.; McCulley, Daniel R.; Lotfizadeh, Neda; Deshpande, Vikram V.; Minot, Ethan D.

2018-02-01

Suspended metallic carbon nanotubes (m-CNTs) exhibit a remarkably large transport gap that can exceed 100 meV. Both experiment and theory suggest that strong electron-electron interactions play a crucial role in generating this electronic structure. To further understand this strongly interacting system, we have performed electronic measurements of suspended m-CNTs with known diameter and chiral angle. Spectrally resolved photocurrent microscopy was used to determine m-CNT structure. The room-temperature electrical characteristics of 18 individually contacted m-CNTs were compared to their respective diameter and chiral angle. At the charge neutrality point, we observe a peak in m-CNT resistance that scales exponentially with inverse diameter. Using a thermally activated transport model, we estimate that the transport gap is (450 meV nm)/D , where D is CNT diameter. We find no correlation between the gap and the CNT chiral angle. Our results add important constraints to theories attempting to describe the electronic structure of m-CNTs.

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.

Photophysics of Carbon Nanotubes Interfaced with Organic and Inorganic Materials

CERN Document Server

Levitsky, Igor A; Karachevtsev, Victor A

2012-01-01

Photophysics of Carbon Nanotubes Interfaced with Organic and Inorganic Materials describes physical, optical and spectroscopic properties of the emerging class of nanocomposites formed from carbon nanotubes (CNTs)  interfacing with organic and inorganic materials. The three main chapters detail novel trends in  photophysics related to the interaction of  light with various carbon nanotube composites from relatively simple CNT/small molecule assemblies to complex hybrids such as CNT/Si and CNT/DNA nanostructures.   The latest experimental results are followed up with detailed discussions and scientific and technological perspectives to provide a through coverage of major topics including: ·   Light harvesting, energy conversion, photoinduced charge separation  and transport  in CNT based nanohybrids · CNT/polymer composites exhibiting photoactuation; and ·         Optical  spectroscopy  and structure of CNT/DNA complexes. Including original data and a short review of recent research, Phot...

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.

Thermodynamics on Soluble Carbon Nanotubes: How Do DNA Molecules Replace Surfactants on Carbon Nanotubes?

Science.gov (United States)

Kato, Yuichi; Inoue, Ayaka; Niidome, Yasuro; Nakashima, Naotoshi

2012-01-01

Here we represent thermodynamics on soluble carbon nanotubes that enables deep understanding the interactions between single-walled carbon nanotubes (SWNTs) and molecules. We selected sodium cholate and single-stranded cytosine oligo-DNAs (dCn (n = 4, 5, 6, 7, 8, 10, 15, and 20)), both of which are typical SWNT solubilizers, and successfully determined thermodynamic properties (ΔG, ΔH and ΔS values) for the exchange reactions of sodium cholate on four different chiralities of SWNTs ((n,m) = (6,5), (7,5), (10,2), and (8,6)) for the DNAs. Typical results contain i) the dC5 exhibited an exothermic exchange, whereas the dC6, 8, 10, 15, and 20 materials exhibited endothermic exchanges, and ii) the energetics of the dC4 and dC7 exchanges depended on the associated chiral indices and could be endothermic or exothermic. The presented method is general and is applicable to any molecule that interacts with nanotubes. The study opens a way for science of carbon nanotube thermodynamics. PMID:23066502

Amorphous molecular junctions produced by ion irradiation on carbon nanotubes

International Nuclear Information System (INIS)

Wang Zhenxia; Yu Liping; Zhang Wei; Ding Yinfeng; Li Yulan; Han Jiaguang; Zhu Zhiyuan; Xu Hongjie; He Guowei; Chen Yi; Hu Gang

2004-01-01

Experiments and molecular dynamics have demonstrated that electron irradiation could create molecular junctions between crossed single-wall carbon nanotubes. Recently molecular dynamics computation predicted that ion irradiation could also join single-walled carbon nanotubes. Employing carbon ion irradiation on multi-walled carbon nanotubes, we find that these nanotubes evolve into amorphous carbon nanowires, more importantly, during the process of which various molecular junctions of amorphous nanowires are formed by welding from crossed carbon nanotubes. It demonstrates that ion-beam irradiation could be an effective way not only for the welding of nanotubes but also for the formation of nanowire junctions

Interaction between fullerene halves C{sub n} (n ≤ 40) and single wall carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Sharma, Amrish, E-mail: amrish99@gmail.com; Kaur, Sandeep, E-mail: sipusukhn@gmail.com [Department of Physics, Punjabi University, Patiala (India); Mudahar, Isha, E-mail: isha@pbi.ac.in [Department of Basic and Applied Sciences, Punjabi University, Patiala (India)

2016-05-06

We have investigated the structural and electronic properties of carbon nanotube with small fullerene halves C{sub n} (n ≤ 40) which are covalently bonded to the side wall of an armchair single wall carbon nanotube (SWCNT) using first principle method based on density functional theory. The fullerene size results in weak bonding between fullerene halves and carbon nanotube (CNT). Further, it was found that the C-C bond distance that attaches the fullerene half and CNT is of the order of 1.60 Å. The calculated binding energies indicate the stability of the complexes formed. The HOMO-LUMO gaps and electron density of state plots points towards the metallicity of the complex formed. Our calculations on charge transfer reveal that very small amount of charge is transferred from CNT to fullerene halves.

Mechanical and electrical properties of low density polyethylene filled with carbon nanotubes

International Nuclear Information System (INIS)

Sabet, Maziyar; Soleimani, Hassan

2014-01-01

Carbon nanotubes (CNTs) reveal outstanding electrical and mechanical properties in addition to nanometer scale diameter and high aspect ratio, consequently, making it an ideal reinforcing agent for high strength polymer composites. Low density polyethylene (LDPE)/CNT composites were prepared via melt compounding. Mechanical and electrical properties of (LDPE)/CNT composites with different CNT contents were studied in this research

Preparation and characterization of Z-shaped carbon nanotubes via decomposing magnesium acetate

International Nuclear Information System (INIS)

Yuan Dingsheng; Liu Yingliang; Xiao Yong; Chen Liqiang

2008-01-01

Novel carbon tubes with a diameter of 200-500 nm and a length of 3-5 μm have been synthesized via decomposing magnesium acetate. Novel carbon tubes have been analyzed and characterized using by X-ray diffraction, scanning electron microscope, transmission electron microscope, selected area electron diffraction (SAED) and Raman spectrum. The analysis results indicate that the graphitic degree of novel carbon tubes is low under our synthesis condition. Interestingly, inside these tubes, smaller Z-shaped carbon nanotubes (CNTs) are formed. The unusual morphologies have not been reported before. A tentative formation mechanism is proposed

Synthesis and utilization of carbon nanotubes for fabrication of electrochemical biosensors

International Nuclear Information System (INIS)

Lawal, Abdulazeez T.

2016-01-01

Graphical abstract: Carbon nanotubes. - Highlights: • This review discusses synthesis and applications of carbon nanotubes sensors. • The review summarizes contributions of carbon nanotube to electrochemical biosensor. • Good electrical conductivity makes carbon nanotubes a good material for biosensors. • Carbon nanotubes promotes electron transfer that aids biosensing of biomolecules. - Abstract: This review summarizes the most recent contributions in the fabrication of carbon nanotubes-based electrochemical biosensors in recent years. It discusses the synthesis and application of carbon nanotubes to the assembly of carbon nanotube-based electrochemical sensors, its analytical performance and future expectations. An increasing number of reviews and publications involving carbon nanotubes sensors have been reported ever since the first design of carbon nanotube electrochemical biosensors. The large surface area and good electrical conductivity of carbon nanotubes allow them to act as “electron wire” between the redox center of an enzyme or protein and an electrode's surface, which make them very excellent material for the design of electrochemical biosensors. Carbon nanotubes promote the different rapid electron transfers that facilitate accurate and selective detection of cytochrome-c, β-nicotinamide adenine dinucleotide, hemoglobin and biomolecules, such as glucose, cholesterol, ascorbic acid, uric acid, dopamine pesticides, metals ions and hydrogen peroxide.

Synthesis and utilization of carbon nanotubes for fabrication of electrochemical biosensors

Energy Technology Data Exchange (ETDEWEB)

Lawal, Abdulazeez T., E-mail: abdul.lawal@yahoo.com

2016-01-15

Graphical abstract: Carbon nanotubes. - Highlights: • This review discusses synthesis and applications of carbon nanotubes sensors. • The review summarizes contributions of carbon nanotube to electrochemical biosensor. • Good electrical conductivity makes carbon nanotubes a good material for biosensors. • Carbon nanotubes promotes electron transfer that aids biosensing of biomolecules. - Abstract: This review summarizes the most recent contributions in the fabrication of carbon nanotubes-based electrochemical biosensors in recent years. It discusses the synthesis and application of carbon nanotubes to the assembly of carbon nanotube-based electrochemical sensors, its analytical performance and future expectations. An increasing number of reviews and publications involving carbon nanotubes sensors have been reported ever since the first design of carbon nanotube electrochemical biosensors. The large surface area and good electrical conductivity of carbon nanotubes allow them to act as “electron wire” between the redox center of an enzyme or protein and an electrode's surface, which make them very excellent material for the design of electrochemical biosensors. Carbon nanotubes promote the different rapid electron transfers that facilitate accurate and selective detection of cytochrome-c, β-nicotinamide adenine dinucleotide, hemoglobin and biomolecules, such as glucose, cholesterol, ascorbic acid, uric acid, dopamine pesticides, metals ions and hydrogen peroxide.