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Sample records for metallic single-wall carbon

  1. Metal-doped single-walled carbon nanotubes and production thereof

    DOEpatents

    Dillon, Anne C.; Heben, Michael J.; Gennett, Thomas; Parilla, Philip A.

    2007-01-09

    Metal-doped single-walled carbon nanotubes and production thereof. The metal-doped single-walled carbon nanotubes may be produced according to one embodiment of the invention by combining single-walled carbon nanotube precursor material and metal in a solution, and mixing the solution to incorporate at least a portion of the metal with the single-walled carbon nanotube precursor material. Other embodiments may comprise sputter deposition, evaporation, and other mixing techniques.

  2. Topological Phase Transition in Metallic Single-Wall Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Okuyama, Rin; Izumida, Wataru; Eto, Mikio

    2017-01-01

    The topological phase transition is theoretically studied in a metallic single-wall carbon nanotube (SWNT) by applying a magnetic field B parallel to the tube. The Z topological invariant, winding number, is changed discontinuously when a small band gap is closed at a critical value of B, which can be observed as a change in the number of edge states owing to the bulk-edge correspondence. This is confirmed by numerical calculations for finite SWNTs of ˜1 µm length, using a one-dimensional lattice model to effectively describe the mixing between σ and π orbitals and spin-orbit interaction, which are relevant to the formation of the band gap in metallic SWNTs.

  3. Comparison of metallic silver and copper doping effects on single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kharlamova, M. V.; Niu, J. J.

    2012-10-01

    In this work we performed the filling of single-walled carbon nanotube channels with metallic silver and copper by means of two-step synthesis including imbuing with metal nitrate aqueous solution and further annealing. It has been shown that metal insertion into the nanotube cavities results in the Fermi level upshift and the charge transfer from metal to carbon atoms, thus donor doping of single-walled carbon nanotubes takes place. At the same time, encapsulated silver has a larger donor effect on the carbon nanotubes that has been proved by Raman spectroscopy and X-ray photoelectron spectroscopy.

  4. Random telegraph noise in metallic single-walled carbon nanotubes

    SciTech Connect

    Chung, Hyun-Jong; Woo Uhm, Tae; Won Kim, Sung; Gyu You, Young; Wook Lee, Sang; Ho Jhang, Sung; Campbell, Eleanor E. B.; Woo Park, Yung

    2014-05-12

    We have investigated random telegraph noise (RTN) observed in individual metallic carbon nanotubes (CNTs). Mean lifetimes in high- and low-current states, τ{sub high} and τ{sub low}, have been studied as a function of bias-voltage and gate-voltage as well as temperature. By analyzing the statistics and features of the RTN, we suggest that this noise is due to the random transition of defects between two metastable states, activated by inelastic scattering with conduction electrons. Our results indicate an important role of defect motions in the 1/f noise in CNTs.

  5. Process for separating metallic from semiconducting single-walled carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Sun, Ya-Ping (Inventor)

    2008-01-01

    A method for separating semiconducting single-walled carbon nanotubes from metallic single-walled carbon nanotubes is disclosed. The method utilizes separation agents that preferentially associate with semiconducting nanotubes due to the electrical nature of the nanotubes. The separation agents are those that have a planar orientation, .pi.-electrons available for association with the surface of the nanotubes, and also include a soluble portion of the molecule. Following preferential association of the separation agent with the semiconducting nanotubes, the agent/nanotubes complex is soluble and can be solubilized with the solution enriched in semiconducting nanotubes while the residual solid is enriched in metallic nanotubes.

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

    PubMed

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

    2014-10-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  8. Transition of single-walled carbon nanotubes from metallic to semiconducting in field-effect transistors by hydrogen plasma treatment.

    PubMed

    Zheng, Gang; Li, Qunqing; Jiang, Kaili; Zhang, Xiaobo; Chen, Jia; Ren, Zheng; Fan, Shoushan

    2007-06-01

    We report hydrogen plasma treatment results on converting the metallic single-walled carbon nanotubes to semiconducting single-walled carbon nanotubes. We found that the as-grown single-walled carbon nanotubes (SWNTs) can be sorted as three groups which behave as metallic, as-metallic, and semiconducting SWNTs. These three groups have different changes under hydrogen plasma treatment and successive annealing process. The SWNTs can be easily hydrogenated in the hydrogen plasma environment and the as-metallic SWNTs can be transformed to semiconducting SWNTs. The successive annealing process can break the C-H bond, so the conversion is reversible.

  9. Characterizations of Enriched Metallic Single-Walled Carbon Nanotubes in Polymer Composite

    NASA Technical Reports Server (NTRS)

    Chen, Bin; Li, Jing; Lu, Yijiang; Cinke, Martin; Au, Dyng; Harmon, Julie P.; Muisener, Patricia Anne O.; Clayton, LaNetra; D'Angelo, John

    2003-01-01

    Using different processing conditions, we disperse the single-walled carbon nanotube (SWNT) into the polymethyl methacrylate (PMMA) to form composites. In the melt-blended sample, the SWNTs originally semiconducting - became predominantly metallic after dispersion into the melt-blended composite. The interaction of the PMMA and SWNT is investigated by the polarized Raman studies. The structure changes in the PMMA and SWNT shows that the anisotropic interactions are responsible for SWNT electronic density of states (DOS) changes. The increased metallic SWNT percentage is confirmed by the conductivity and dielectric constant measurements .

  10. Metallic Catalysts for Structure-Controlled Growth of Single-Walled Carbon Nanotubes.

    PubMed

    Li, Meihui; Liu, Xiyan; Zhao, Xiulan; Yang, Feng; Wang, Xiao; Li, Yan

    2017-04-01

    Single-walled carbon nanotubes (SWNTs) have shown great potential in various applications attributed to their unique structures and outstanding structure-dependent properties. The structure-controlled growth of SWNTs is a crucial issue for their advanced applications and has been a great challenge in this field for two decades. Metal catalyst-mediated SWNT growth is believed to be very efficient. In this review, progresses in diameter and chirality controlled growth of SWNTs with metal catalysts is summarized from several aspects, including growth mechanism and theory, effects of catalysts, and the chemical vapor deposition conditions. The design, preparation, handling and dispersion, and the size evolution of metal catalysts are all discussed. The influences of growth environment including the type, composition, and pressure/concentration of the carbon source as well as the temperature on the selectivity toward the nanotube structure are analyzed. We also discuss some of the challenges and trends in this field.

  11. Effect of doping on single-walled carbon nanotubes network of different metallicity.

    PubMed

    Tey, Ju Nie; Ho, Xinning; Wei, Jun

    2012-10-03

    Effects of doping on single-walled carbon nanotubes (SWNT) networks with different metallicity are reported through the study of sheet resistance changes upon annealing and acid treatment. SWNT film with high metallic tube content is found to have relatively good chemical stability against post treatments, as demonstrated from its stable film performance in ambient after annealing, and merely 15% reduction in sheet resistance upon sulfuric acid treatment. Conversely, film stability of SWNT film with low metallic content which comprises largely of semiconducting SWNT varies with days in ambient, and its sheet resistance changes drastically after treated with acid, indicating the extreme sensitivity of semiconducting SWNT to surrounding environment. The results suggest that annealing removes unintentional oxygen doping from the ambient and shifts the Fermi level towards the intrinsic Fermi level. Acid treatment, on the other hand, introduces physisorbed and chemisorbed oxygen and shifts the Fermi level away from the intrinsic level and increases the hole doping.

  12. Growth of Single-Walled Carbon Nanotubes by High Melting Point Metal Oxide Catalysts

    NASA Astrophysics Data System (ADS)

    Qian, Yang; Xiang, Rong; An, Hua; Inoue, Taiki; Chiashi, Shohei; Maruyama, Shigeo

    We report on the growth of single-walled carbon nanotubes (SWNTs) from Co oxide catalysts. The concept is using the relatively lower mobility of metal oxide (than metal) to suppress catalyst aggregation at high temperatures. Compared to the SWNTs grown by pre-reduced catalysts, SWNTs grown from oxidized Co catalysts have shown narrower diameter distribution and smaller average diameter. Different growth parameters are discussed regarding the resulting morphology of SWNTs. Transmission electron microscopy (TEM) investigations reveal the information that Co catalysts are transformed to Co3O4 after reduction-calcination process. X-ray photoelectron spectroscopy (XPS) investigations indicate that Co3O4 has decomposed to CoO before growth at a typical growth temperature (800 ºC) in Ar atmosphere. We propose that CoO has higher melting point than Co and thus is more stable during the growth. Our results indicate that besides the bimetallic catalysts, monometallic catalytic system could also be useful in stabilizing the catalysts to grow chirality-specific SWNTs by transforming the relatively low melting point metal catalysts to high melting point metal oxide catalysts. Yang Qian was supported through ``Global Leader Program for Social Design and Management''.

  13. Structure and magnetic response of a residual metal catalyst in highly purified single walled carbon nanotubes.

    PubMed

    Bittova, Barbara Pacakova; Kalbac, Martin; Kubickova, Simona; Mantlikova, Alice; Mangold, Stephen; Vejpravova, Jana

    2013-04-28

    This article presents methods for detailed physical analysis of partial steps leading to the removal of residual metal catalyst nanoparticles (NPs) from single walled carbon nanotubes (SWCNTs) and options for detecting negligible amounts of metal in samples possessing diamagnetic response. Based on the previous knowledge of the composition, structure and magnetic properties of NPs included in the commercial HiPco_raw and HiPco_SP SWCNTs, the properties of remaining NPs after the multi-step purification (oxidation followed by mild acid treatment) and annealing both under static and dynamic vacuum have been investigated. Thermogravimetry, X-ray diffraction, static and dynamic magnetic property measurements and the Extended X-ray Absorption Fine Structure (EXAFS) experiments have been performed. The data provide information about the nature of the residual NPs in purified SWCNTs, which is crucial for further understanding of the purification processes and their improvement. It has been demonstrated that even if all macroscopic methods indicate a high purity of the treated sample, a non-negligible amount of the metal may still be present and the metal content has to be examined using local and element sensitive probes such as EXAFS.

  14. Valley coupling in finite-length metallic single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Izumida, W.; Okuyama, R.; Saito, R.

    2015-06-01

    Degeneracy of discrete energy levels of finite-length, metallic single-wall carbon nanotubes depends on the type of nanotubes, boundary condition, length of nanotubes, and spin-orbit interaction. Metal-1 nanotubes, in which two nonequivalent valleys in the Brillouin zone have different orbital angular momenta with respect to the tube axis, exhibit nearly fourfold degeneracy and small lift of the degeneracy by the spin-orbit interaction reflecting the decoupling of two valleys in the eigenfunctions. In metal-2 nanotubes, in which the two valleys have the same orbital angular momentum, vernier-scale-like spectra appear for boundaries of orthogonal-shaped edge or cap termination reflecting the strong valley coupling and the asymmetric velocities of the Dirac states. Lift of the fourfold degeneracy by parity splitting overcomes the spin-orbit interaction in shorter nanotubes with a so-called minimal boundary. Slowly decaying evanescent modes appear in the energy gap induced by the curvature of nanotube surface. Effective one-dimensional lattice model reveals the role of boundary on the valley coupling in the eigenfunctions.

  15. Thermal analysis for laser selective removal of metallic single-walled carbon nanotubes

    SciTech Connect

    Song, Jizhou; Li, Yuhang; Du, Frank; Xie, Xu; Rogers, John A.; Huang, Yonggang

    2015-04-28

    Single-walled carbon nanotubes (SWNTs) have been envisioned as one of the best candidates for future semiconductors due to their excellent electrical properties and ample applications. However, SWNTs grow as mixture of both metallic and semiconducting tubes and this heterogeneity hampers their practical applications. Laser radiation shows promises to remove metallic SWNTs (m-SWNTs) in air under an appropriate condition. We established a scaling law, validated by finite element simulations, for the temperature rise of m-SWNTs under a pulsed laser with a Gaussian spot. It is shown that the maximum normalized m-SWNT temperature rise only depends on two non-dimensional parameters: the normalized pulse duration time and the normalized interfacial thermal resistance. In addition, the maximum temperature rise is inversely proportional to the square of spot size and proportional to the incident laser power. These results are very helpful to understand the underlying physics associated with the removal process and provides easily interpretable guidelines for further optimizations.

  16. Metal coated functionalized single-walled carbon nanotubes for composite applications

    NASA Astrophysics Data System (ADS)

    Zeng, Qiang

    This study is considered as a method for producing multifunctional composite materials by using metals coated Single-walled Carbon Nanotubes (SWCNTs). In this research, various metals (Ni, Cu, Ag) were successfully deposited onto the surface of SWCNTs. It has been found that homogenous dispersion and dense nucleation sites are the necessary conditions to form uniform coatings on SWCNTs. Functionalization has been applied to achieve considerable improvement in the dispersion of purified SWCNTs and creates more nucleation sites for subsequent metal deposition. A three-step electroless plating approach was used and the coating mechanism is described in the paper. The samples were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Raman spectroscopy, fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). Bulk copper/aluminum-SWNT composites were processed by powder metallurgy with wet mixing techniques. Coated SWCNTs were well dispersed in the metal matrix. Cold pressing followed by sintering was applied to control porosity. The relationships between hardness and SWCNTs addition were discussed. Ni-SWCNTs composite coatings were prepared by electro-composite deposition. SWCNTs were suspended in a Ni deposition electrolyte and deposited together with nickel during electrodeposition. SWCNTs concentrations in the coatings were found to be related to the SWCNTs concentration in the solution, current density and agitation rate. The microstructure of the coatings has been examined by electron microscopy. Ni coated SWCNTs were also incorporated into the high temperature Bismaleimide (BMI)/graphite composite to improve Electromagnetic Interference (EMI) shielding and surface conductivity. The vacuum assisted resin transfer molding (VARTM) was used to process these composites. Surface and volume resistivity and EMI shielding effectiveness of the composites

  17. Development of Metal-impregnated Single Walled Carbon Nanotubes for Toxic Gas Contaminant Control in Advanced Life Support Systems

    NASA Technical Reports Server (NTRS)

    Pisharody, Suresh A.; Fisher, John W.; Wignarajah, K.

    2002-01-01

    The success of physico-chemical waste processing and resource recovery technologies for life support application depends partly on the ability of gas clean-up systems to efficiently remove trace contaminants generated during the process with minimal use of expendables. Carbon nanotubes promise superior performance over conventional approaches to gas clean-up due to their ability to direct the selective uptake of gaseous species based on their controlled pore size, high surface area, ordered chemical structure that allows functionalization and their effectiveness also as catalyst support materials for toxic gas conversion. We present results and findings from a preliminary study on the effectiveness of metal impregnated single walled nanotubes as catalyst/catalyst support materials for toxic gas contaminate control. The study included the purification of single walled nanotubes, the catalyst impregnation of the purified nanotubes, the experimental characterization of the surface properties of purified single walled nanotubes and the characterization of physisorption and chemisorption of uptake molecules.

  18. Effect of metal oxide and oxygen on the growth of single-walled carbon nanotubes by electric arc discharge

    NASA Astrophysics Data System (ADS)

    He, Delong; Liu, Yongning; Zhao, Tingkai; Zhu, Jiewu; Yu, Guang

    2008-03-01

    The effect of oxygen on the growth of single-walled carbon nanotubes was studied with Ni-Co alloy powder as catalyst under helium atmosphere of 500 Torr by electric arc discharge. The oxygen included in nickel or (and) cobalt oxides was added in catalyst. The content of oxygen in atmosphere was controlled by changing vacuum degree inside furnace before inputting buffer gas. The examinations of TEM and Raman scattering showed that oxygen in metal oxide as catalyst promotes the nucleation of SWCNT by taking effect on the metal catalyst particles. However, O2 in atmosphere has the role of oxidizing amorphous particles along with nanotubes. When its molar proportion is higher than 0.22 ppm (Parts per million), the carbon nanotubes produced are oxidized and their purity decreases. The diameter of single-walled carbon nanotube obtained under different condition has a narrow distribution around 1.28 nm.

  19. Selective nuclear localization of siRNA by metallic versus semiconducting single wall carbon nanotubes in keratinocytes

    PubMed Central

    Huzil, John Torin; Saliaj, Evi; Ivanova, Marina V; Gharagozloo, Marjan; Loureiro, Maria Jimena; Lamprecht, Constanze; Korinek, Andreas; Chen, Ding Wen; Foldvari, Marianna

    2015-01-01

    Background: The potential use of carbon nanotubes (CNTs) in gene therapy as delivery systems for nucleic acids has been recently recognized. Here, we describe that metallic versus semiconducting single-wall CNTs can produce significant differences in transfection rate and cellular distribution of siRNA in murine PAM212 keratinocytes. Results/Methodology: The results of cell interaction studies, coupled with supportive computational simulations and ultrastructural studies revealed that the use of metallic single wall CNTs resulted in siRNA delivery into both the cytoplasm and nucleus of keratinocytes, whereas semiconducting CNTs resulted in delivery only to the cytoplasm. Conclusion: Using enriched fractions of metallic or semiconducting CNTs for siRNA complex preparation may provide specific subcellular targeting advantages. PMID:28031892

  20. Growth of vertically aligned single-walled carbon nanotubes with metallic chirality through faceted FePt-Au catalysts

    NASA Astrophysics Data System (ADS)

    Ohashi, Toshiyuki; Iwama, Hiroki; Shima, Toshiyuki

    2016-02-01

    Direct synthesis of vertically aligned metallic single-walled carbon nanotubes (m-SWCNT forests) is a difficult challenge. We have successfully synthesized m-SWCNT forests using faceted iron platinum-gold catalysts epitaxially grown on a single crystalline magnesium oxide substrate. The metallic content of the forests estimated by Raman spectroscopy reaches 90%. From the standpoint of growth rate of the forests, the growth mechanism is probably based on the catalyst of solid state. It is suggested that preferential growth of m-SWCNTs is achieved when both factors are satisfied, namely, {111} dominant octahedral facet and ideal size (fine particles) of FePt particles.

  1. High-performance hydrogen production and oxidation electrodes with hydrogenase supported on metallic single-wall carbon nanotube networks.

    PubMed

    Svedružić, Draženka; Blackburn, Jeffrey L; Tenent, Robert C; Rocha, John-David R; Vinzant, Todd B; Heben, Michael J; King, Paul W

    2011-03-30

    We studied the electrocatalytic activity of an [FeFe]-hydrogenase from Clostridium acetobutylicum (CaH2ase) immobilized on single-wall carbon nanotube (SWNT) networks. SWNT networks were prepared on carbon cloth by ultrasonic spraying of suspensions with predetermined ratios of metallic and semiconducting nanotubes. Current densities for both proton reduction and hydrogen oxidation electrocatalytic activities were at least 1 order of magnitude higher when hydrogenase was immobilized onto SWNT networks with high metallic tube (m-SWNT) content in comparison to hydrogenase supported on networks with low metallic tube content or when SWNTs were absent. We conclude that the increase in electrocatalytic activities in the presence of SWNTs was mainly due to the m-SWNT fraction and can be attributed to (i) substantial increases in the active electrode surface area, and (ii) improved electronic coupling between CaH2ase redox-active sites and the electrode surface.

  2. Development of Metal-impregnated Single Walled Carbon Nanotubes for Toxic Gas Contaminant Control in Advanced Life Support Systems

    NASA Technical Reports Server (NTRS)

    Cinke, Martin; Li, Jing; Chen, Bin; Wignarajah, Kanapathipillai; Pisharody, Suresh A.; Fisher, John W.; Delzeit, Lance; Meyyappan, Meyya; Partridge, Harry; Clark, Kimberlee

    2003-01-01

    The success of physico-chemical waste processing and resource recovery technologies for life support application depends partly on the ability of gas clean-up systems to efficiently remove trace contaminants generated during the process with minimal use of expendables. Highly purified metal-impregnated carbon nanotubes promise superior performance over conventional approaches to gas clean-up due to their ability to direct the selective uptake gaseous species based both on the nanotube s controlled pore size, high surface area, and ordered chemical structure that allows functionalization and on the nanotube s effectiveness as a catalyst support material for toxic contaminants removal. We present results on the purification of single walled carbon nanotubes (SWCNT) and efforts at metal impregnation of the SWCNT's.

  3. Bulk electrical properties of single-walled carbon nanotubes immobilized by dielectrophoresis: evidence of metallic or semiconductor behavior.

    PubMed

    Mureau, Natacha; Watts, Paul C P; Tison, Yann; Silva, S Ravi P

    2008-06-01

    We report the electrical characterization of single-walled carbon nanotubes (SWCNTs) trapped between two electrodes by dielectrophoresis (DEP). At high frequency, SWCNTs collected by DEP are expected to be of metallic type. Indeed current-voltage (I-V) measurements for devices made at 10 MHz show high values of conductivity and exhibit metallic behavior with linear and symmetric electrical features attributed to ohmic conduction. At low frequency, SWCNTs attracted by DEP are expected to be of semiconducting nature. Devices made at 10 kHz behave as semiconductors and demonstrate nonlinear and rectifying electrical characteristics with conductivities many orders of magnitude below the sample resulting from high-frequency immobilization of SWCNTs. Conducting atomic force microscopy (C-AFM) and current density calculation results are presented to reinforce results obtained by I-V measurements which clearly show type separation of SWCNTs after DEP experiments.

  4. Rare-earth metal halogenide encapsulation-induced modifications in Raman spectra of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kharlamova, M. V.

    2015-01-01

    In the present work, a detailed Raman spectroscopy investigation on the single-walled carbon nanotubes (SWCNTs) filled with praseodymium chloride, terbium chloride and thulium chloride was performed. The salts were incorporated inside the SWCNTs by a capillary filling method using melts, and the high-resolution transmission electron microscopy data proved the high filling degree of the nanotube channels. A thorough analysis of the radial breathing mode and G-band of the Raman spectra of the pristine and filled SWCNTs showed that the encapsulated salts cause acceptor doping of the host nanotubes, and the doping efficiency depends on the compound. The incorporated thulium chloride has the strongest doping effect on the SWCNTs, whereas praseodymium chloride has the weakest effect. It was found that the encapsulated salts modify more significantly the electronic structure of metallic nanotubes than semiconducting SWCNTs.

  5. Impregnation of Catalytic Metals in Single-Walled Carbon Nanotubes for Toxic Gas Conversion in Life Support System

    NASA Technical Reports Server (NTRS)

    Li, Jing; Wignarajah, Kanapathipillai; Cinke, Marty; Partridge, Harry; Fisher, John

    2004-01-01

    Carbon nanotubes (CNTs) possess extraordinary properties such as high surface area, ordered chemical structure that allows functionalization, larger pore volume, and very narrow pore size distribution that have attracted considerable research attention from around the world since their discovery in 1991. The development and characterization of an original and innovative approach for the control and elimination of gaseous toxins using single walled carbon nanotubes (SWNTs) promise superior performance over conventional approaches due to the ability to direct the selective uptake of gaseous species based on their controlled pore size, increased adsorptive capacity due to their increased surface area and the effectiveness of carbon nanotubes as catalyst supports for gaseous conversion. We present our recent investigation of using SWNTs as catalytic supporting materials to impregnate metals, such as rhodium (Rh), palladium (Pd) and other catalysts. A protocol has been developed to oxidize the SWNTs first and then impregnate the Rh in aqueous rhodium chloride solution, according to unique surface properties of SWNTs. The Rh has been successfully impregnated in SWNTs. The Rh-SWNTs have been characterized by various techniques, such as TGA, XPS, TEM, and FTIR. The project is funded by a NASA Research Announcement Grant to find applications of single walled nanocarbons in eliminating toxic gas Contaminant in life support system. This knowledge will be utilized in the development of a prototype SWNT KO, gas purification system that would represent a significant step in the development of high efficiency systems capable of selectively removing specific gaseous for use in regenerative life support system for human exploration missions.

  6. Intertube effects on one-dimensional correlated state of metallic single-wall carbon nanotubes probed by 13C NMR

    NASA Astrophysics Data System (ADS)

    Serita, Noboru; Nakai, Yusuke; Matsuda, Kazuyuki; Yanagi, Kazuhiro; Miyata, Yasumitsu; Saito, Takeshi; Maniwa, Yutaka

    2017-01-01

    The electronic states in isolated single-wall carbon nanotubes (SWCNTs) have been considered as an ideal realization of a Tomonaga-Luttinger liquid (TLL). However, it remains unclear whether one-dimensional correlated states are realized under local environmental effects such as the formation of a bundle structure. Intertube effects originating from other adjacent SWCNTs within a bundle may drastically alter the one-dimensional correlated state. In order to test the validity of the TLL model in bundled SWCNTs, low-energy spin excitation is investigated by nuclear magnetic resonance (NMR). The NMR relaxation rate in bundled mixtures of metallic and semiconducting SWCNTs shows a power-law temperature dependence with a theoretically predicted exponent. This demonstrates that a TLL state with the same strength as that for effective Coulomb interactions is realized in a bundled sample, as in isolated SWCNTs. In bundled metallic SWCNTs, we found a power-law temperature dependence of the relaxation rate, but the magnitude of the relaxation rate is one order of magnitude smaller than that predicted by theory. Furthermore, we found an almost doubled magnitude of the Luttinger parameter. These results indicate suppressed spin excitations with reduced Coulomb interactions in bundled metallic SWCNTs, which are attributable to intertube interactions originating from adjacent metallic SWCNTs within a bundle. Our findings give direct evidence that bundling reduces the effective Coulomb interactions via intertube interactions within bundled metallic SWCNTs.

  7. Noble metal coated single-walled carbon nanotubes for applications in surface enhanced Raman scattering imaging and photothermal therapy.

    PubMed

    Wang, Xiaojing; Wang, Chao; Cheng, Liang; Lee, Shuit-Tong; Liu, Zhuang

    2012-05-02

    Single-walled carbon nanotubes (SWNTs) with various unique optical properties are interesting nanoprobes widely explored in biomedical imaging and phototherapies. Herein, DNA-functionalized SWNTs are modified with noble metal (Ag or Au) nanoparticles via an in situ solution phase synthesis method comprised of seed attachment, seeded growth, and surface modification with polyethylene glycol (PEG), yielding SWNT-Ag-PEG and SWNT-Au-PEG nanocomposites stable in physiological environments. With gold or silver nanoparticles decorated on the surface, the SWNT-metal nanocomposites gain an excellent concentration and excitation-source dependent surface-enhanced Raman scattering (SERS) effect. Using a near-infrared (NIR) laser as the excitation source, targeted Raman imaging of cancer cells labeled with folic acid (FA) conjugated SWNT-Au nanocomposite (SWNT-Au-PEG-FA) is realized, with images acquired in significantly shortened periods of time as compared to that of using nonenhanced SWNT Raman probes. Owing to the strong surface plasmon resonance absorption contributed by the gold shell, the SWNTs-Au-PEG-FA nanocomposite also offers remarkably improved photothermal cancer cell killing efficacy. This work presents a facile approach to synthesize water-soluble noble metal coated SWNTs with a strong SERS effect suitable for labeling and fast Raman spectroscopic imaging of biological samples, which has been rarely realized before. The SWNT-Au-PEG nanocomposite developed here may thus be an interesting optical theranostic probe for cancer imaging and therapy.

  8. Hydrogen Storage in metal-modified single-walled carbon nanotubes

    SciTech Connect

    Dr. Ahn

    2004-04-30

    It has been known for over thirty years that potassium-intercalated graphites can readily adsorb and desorb hydrogen at {approx}1 wt% at 77 K. These levels are much higher than can be attained in pure graphite, owing to a larger thermodynamic enthalpy of adsorption. This increased enthalpy may allow hydrogen sorption at higher temperatures. Potassium has other beneficial effects that enable the design of a new material: (a) Increased adsorption enthalpy in potassium-intercalated graphite compared to pure graphite reduces the pressure and increases the temperature required for a given fractional coverage of hydrogen adsorption. We expect the same effects in potassium-intercalated SWNTs. (b) As an intercalant, potassium separates c-axis planes in graphite. Potassium also separates the individual tubes of SWNTs ropes producing swelling and increased surface area. Increased surface area provides more adsorption sites, giving a proportionately higher capacity. The temperature of adsorption depends on the enthalpy of adsorption. The characteristic temperature is roughly the adsorption enthalpy divided by Boltzmann's constant, k{sub B}. For the high hydrogen storage capacity of SWNTs to be achieved at room temperature, it is necessary to increase the enthalpy of adsorption. Our goal for this project was to use metal modifications to the carbon surface of SWNTs in order to address both enhanced adsorption and surface area. For instance, the enthalpy of sorption of hydrogen on KC8 is 450 meV/H{sub 2}, whereas it is 38 meV/H{sub 2} for unmodified SWNTs. By adsorption thermodynamics we expect approximately that the same performance of SWNTs at 77 K will be achieved at a temperature of [450/38] 77 K = 900 K. This is a high temperature, so we expect that adsorption on nearly all the available sites for hydrogen will occur at room temperature under a much lower pressure. This pressure can be estimated conveniently, since the chemical potential of hydrogen is approximately

  9. A rational design for the separation of metallic and semiconducting single-walled carbon nanotubes using a magnetic field

    NASA Astrophysics Data System (ADS)

    Luo, Chengzhi; Wan, Da; Jia, Junji; Li, Delong; Pan, Chunxu; Liao, Lei

    2016-06-01

    The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm2 V-1 s-1 and an on/off ratio of 106. We also established a model to quantitatively calculate the percentage of m-SWNTs on the substrate and this model shows a good match with the experimental data. Furthermore, our rational design also provides a new avenue for the growth of SWNTs with specific chirality and manipulated arrangement due to the difference of magnetic susceptibilities between different diameters, chiralities, and types.The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm2 V-1 s-1 and an on/off ratio of 106. We also established a model to quantitatively calculate the percentage of m

  10. Quantitative Separation of Single-Walled Carbon Nanotubes into Metallic and Semiconducting Fractions

    DTIC Science & Technology

    2012-08-15

    Boron Nitride Nanocomposite Materials for Superior Thermal Transport Performance ” Angew. Chem. Int. Ed. 2012, 51, 6498–6501. (12) Song, W.-L.; Wang, W...Veca, L. M.; Kong, C. Y.; Cao, M.-S.; Wang, P.; Meziani, M. J.; Qian, H.; LeCroy, G. E.; Cao, L.; Sun, Y.-P. “ Polymeric /Carbon Nanocomposites for... PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10

  11. Evaluation of the immunological profile of antibody-functionalized metal-filled single-walled carbon nanocapsules for targeted radiotherapy

    PubMed Central

    Perez Ruiz de Garibay, Aritz; Spinato, Cinzia; Klippstein, Rebecca; Bourgognon, Maxime; Martincic, Markus; Pach, Elzbieta; Ballesteros, Belén; Ménard-Moyon, Cécilia; Al-Jamal, Khuloud T.; Tobias, Gerard; Bianco, Alberto

    2017-01-01

    This study investigates the immune responses induced by metal-filled single-walled carbon nanotubes (SWCNT) under in vitro, ex vivo and in vivo settings. Either empty amino-functionalized CNTs [SWCNT-NH2 (1)] or samarium chloride-filled amino-functionalized CNTs with [SmCl3@SWCNT-mAb (3)] or without [SmCl3@SWCNT-NH2 (2)] Cetuximab functionalization were tested. Conjugates were added to RAW 264.7 or PBMC cells in a range of 1 μg/ml to 100 μg/ml for 24 h. Cell viability and IL-6/TNFα production were determined by flow cytometry and ELISA. Additionally, the effect of SWCNTs on the number of T lymphocytes, B lymphocytes and monocytes within the PBMC subpopulations was evaluated by immunostaining and flow cytometry. The effect on monocyte number in living mice was assessed after tail vein injection (150 μg of each conjugate per mouse) at 1, 7 and 13 days post-injection. Overall, our study showed that all the conjugates had no significant effect on cell viability of RAW 264.7 but conjugates 1 and 3 led to a slight increase in IL-6/TNFα. All the conjugates resulted in significant reduction in monocyte/macrophage cell numbers within PBMCs in a dose-dependent manner. Interestingly, monocyte depletion was not observed in vivo, suggesting their suitability for future testing in the field of targeted radiotherapy in mice. PMID:28198410

  12. Experimental and theoretical comparison of gas desorption energies on metallic and semiconducting single-walled carbon nanotubes.

    PubMed

    Mandeltort, Lynn; Chen, De-Li; Saidi, Wissam A; Johnson, J Karl; Cole, Milton W; Yates, John T

    2013-05-22

    Single-walled carbon nanotubes (SWNTs) exhibit high surface areas and precisely defined pores, making them potentially useful materials for gas adsorption and purification. A thorough understanding of the interactions between adsorbates and SWNTs is therefore critical to predicting adsorption isotherms and selectivities. Metallic (M-) and semiconducting (S-) SWNTs have extremely different polarizabilities that might be expected to significantly affect the adsorption energies of molecules. We experimentally and theoretically show that this expectation is contradicted, for both a long chain molecule (n-heptane) and atoms (Ar, Kr, and Xe). Temperature-programmed desorption experiments are combined with van der Waals corrected density functional theory, examining adsorption on interior and exterior sites of the SWNTs. Our calculations show a clear dependence of the adsorption energy on nanotube diameter but not on whether the tubes are conducting or insulating. We find no significant experimental or theoretical difference in adsorption energies for molecules adsorbed on M- and S-SWNTs having the same diameter. Hence, we conclude that the differences in polarizabilities between M- and S-SWNTs have a negligible influence on gas adsorption for spherical molecules as well as for highly anisotropic molecules such as n-heptane. We expect this conclusion to apply to all types of adsorbed molecules where van der Waals interactions govern the molecular interaction with the SWNT.

  13. Discriminating between Metallic and Semiconducting Single-Walled Carbon Nanotubes Using Physisorbed Adsorbates: Role of Wavelike Charge-Density Fluctuations

    NASA Astrophysics Data System (ADS)

    Gao, Wang; Chen, Yun; Jiang, Qing

    2016-12-01

    Discriminating between metallic (M ) and semiconducting (S ) single-walled carbon nanotubes (SWNTs) remains a fundamental challenge in the field of nanotechnology. We address this issue by studying the adsorption of the isotropic atoms Xe, Kr, and a highly anisotropic molecule n heptane on M - and S -SWNTs with density functional theory that includes many-body dispersion forces. We find that the distinct polarizabilities of M - and S -SWNTs exhibit significantly different physisorption properties, which are also strongly controlled by the SWNT's diameter, adsorption site, adsorbate coverage, and the adsorbate's anisotropy. These findings stem from the wavelike nature of charge-density fluctuations in SWNTs. Particularly, these results allow us to rationalize the unusual √{3 }×√{3 }R 3 00 phase of Kr atoms on small gap M -SWNTs and the double desorption peak temperatures of n heptane on M -SWNTs in experiments, and also propose the n heptane as an effective sensor for experimentally discriminating M - and S -SWNTs.

  14. Evaluation of the immunological profile of antibody-functionalized metal-filled single-walled carbon nanocapsules for targeted radiotherapy

    NASA Astrophysics Data System (ADS)

    Perez Ruiz de Garibay, Aritz; Spinato, Cinzia; Klippstein, Rebecca; Bourgognon, Maxime; Martincic, Markus; Pach, Elzbieta; Ballesteros, Belén; Ménard-Moyon, Cécilia; Al-Jamal, Khuloud T.; Tobias, Gerard; Bianco, Alberto

    2017-02-01

    This study investigates the immune responses induced by metal-filled single-walled carbon nanotubes (SWCNT) under in vitro, ex vivo and in vivo settings. Either empty amino-functionalized CNTs [SWCNT-NH2 (1)] or samarium chloride-filled amino-functionalized CNTs with [SmCl3@SWCNT-mAb (3)] or without [SmCl3@SWCNT-NH2 (2)] Cetuximab functionalization were tested. Conjugates were added to RAW 264.7 or PBMC cells in a range of 1 μg/ml to 100 μg/ml for 24 h. Cell viability and IL-6/TNFα production were determined by flow cytometry and ELISA. Additionally, the effect of SWCNTs on the number of T lymphocytes, B lymphocytes and monocytes within the PBMC subpopulations was evaluated by immunostaining and flow cytometry. The effect on monocyte number in living mice was assessed after tail vein injection (150 μg of each conjugate per mouse) at 1, 7 and 13 days post-injection. Overall, our study showed that all the conjugates had no significant effect on cell viability of RAW 264.7 but conjugates 1 and 3 led to a slight increase in IL-6/TNFα. All the conjugates resulted in significant reduction in monocyte/macrophage cell numbers within PBMCs in a dose-dependent manner. Interestingly, monocyte depletion was not observed in vivo, suggesting their suitability for future testing in the field of targeted radiotherapy in mice.

  15. Electrically Robust Metal Nanowire Network Formation by In-Situ Interconnection with Single-Walled Carbon Nanotubes

    PubMed Central

    Woo, Jong Seok; Han, Joong Tark; Jung, Sunshin; Jang, Jeong In; Kim, Ho Young; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2014-01-01

    Modulation of the junction resistance between metallic nanowires is a crucial factor for high performance of the network-structured conducting film. Here, we show that under current flow, silver nanowire (AgNW) network films can be stabilised by minimizing the Joule heating at the NW-NW junction assisted by in-situ interconnection with a small amount (less than 3 wt%) of single-walled carbon nanotubes (SWCNTs). This was achieved by direct deposition of AgNW suspension containing SWCNTs functionalised with quadruple hydrogen bonding moieties excluding dispersant molecules. The electrical stabilisation mechanism of AgNW networks involves the modulation of the electrical transportation pathway by the SWCNTs through the SWCNT-AgNW junctions, which results in a relatively lower junction resistance than the NW-NW junction in the network film. In addition, we propose that good contact and Fermi level matching between AgNWs and modified SWCNTs lead to the modulation of the current pathway. The SWCNT-induced stabilisation of the AgNW networks was also demonstrated by irradiating the film with microwaves. The development of the high-throughput fabrication technology provides a robust and scalable strategy for realizing high-performance flexible transparent conductor films. PMID:24763208

  16. Intra- and inter-tube exciton relaxation dynamics in high purity semiconducting and metallic single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ichida, Masao; Saito, Shingo; Miyata, Yasumitsu; Yanagi, Kazuhiro; Kataura, Hiromichi; Ando, Hiroaki

    2013-02-01

    We have measured the exciton and carrier dynamics in the high purity semiconducting (S-) and metallic (M-) single-walled carbon nanotubes (SWNTs) in the isolated and aggregated (bundled) forms. The exciton relaxation decay times are measured by using the pump-probe spectroscopy. For bundled samples, the relaxation time becomes shorter than that for isolated SWNTs sample, because of the existence of inter-tube relaxation. We estimate the relaxation rates from S-SWNT to S-SWNT and S-SWNT to M-SWNT using the decay times for isolated SWNTs, high purity S-SWNTs bundle, and doped S-SWNTs in high purity M-SWNTs bundle. For S-SWNTs, inter-tube relaxation plays an important role in the relaxation dynamics. However, for M-SWNTs, the inter-tube relaxation is not so important, and the transition energy and intensity of exciton in M-SWNTs is strongly affected by the photoexcited carriers which plays like as photo doping.

  17. Surfactant free fractions of metallic and semiconducting single-walled carbon nanotubes via optimised gel chromatography

    SciTech Connect

    Lukaszczuk, Pawel; Ruemmeli, Mark H.; Knupfer, Martin; Kalenczuk, Ryszard J.; Borowiak-Palen, Ewa

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer The application of gel permeation chromatography technique in a field of SWCNT separation. Black-Right-Pointing-Pointer Non-commercial agarose gel used as a column filling. Black-Right-Pointing-Pointer Purification route is presented, quality and quantity estimation is shown. Black-Right-Pointing-Pointer Process is ready for high-scale separation of SWCNTs. -- Abstract: We report the procedure of sorting/purification of carbon nanotubes by electronic type using chromatographic column with sodium dodecylsulfate (SDS) and sodium deoxycholate (DOC) solutions as the eluents. The non-commercial agarose gel in different concentrations has been tested in the process. It was found that in optimal gel concentration the fractionation resulted in {approx}96.2% yield of semiconducting species. Importantly, to get surfactant-free fractions the post-separation purification procedure has been carried out. The UV-vis-NIR and Raman spectroscopy have been utilised for the samples analysis. High resolution transmission microscopy and thermogravimetric analysis allowed to study the sample morphology and purity, respectively.

  18. Sheet resistance characterization of locally anisotropic transparent conductive films made of aligned metal-enriched single-walled carbon nanotubes.

    PubMed

    Kang, Hosung; Kim, Duckjong; Baik, Seunghyun

    2014-09-21

    One-dimensional conductive fillers such as single-walled carbon nanotubes (SWNTs) can be aggregated and aligned during transparent conductive film (TCF) formation by the vacuum filtration method. The potential error of analysing the average sheet resistance of these anisotropic films, using the four-point probe in-line method and the conversion formula developed assuming uniform isotropic material properties, was systematically investigated by finite element analysis and experiments. The finite element analysis of anisotropic stripe-patterned TCFs with alternating low (ρ1) and high (ρ2) resistivities revealed that the estimated average sheet resistance approached ρ1/t when the probes were parallel to the aligned nanotubes. The thickness of the film is t. It was more close to ρ2/t when the probes were perpendicular to the aligned tubes. Indeed, TCFs fabricated by the vacuum filtration method using metal-enriched SWNTs exhibited highly anisotropic local regions where tubes were aggregated and aligned. The local sheet resistances of randomly oriented, aligned, and perpendicular tube regions of the TCF at a transmittance of 89.9% were 5000, 2.4, and 12 300 Ω □(-1), respectively. Resistivities of the aggregated and aligned tube region (ρ1 = 1.2 × 10(-5) Ω cm) and the region between tubes (ρ2 = 6.2 × 10(-2) Ω cm) could be approximated with the aid of finite element analysis. This work demonstrates the potential error of characterizing the average sheet resistance of anisotropic TCFs using the four-point probe in-line method since surprisingly high or low values could be obtained depending on the measurement angle. On the other hand, a better control of aggregation and alignment of nanotubes would realize TCFs with a very small anisotropic resistivity and a high transparency.

  19. Single-Walled Carbon Nanotubes: Mimics of Biological Ion Channels

    PubMed Central

    2017-01-01

    Here we report on the ion conductance through individual, small diameter single-walled carbon nanotubes. We find that they are mimics of ion channels found in natural systems. We explore the factors governing the ion selectivity and permeation through single-walled carbon nanotubes by considering an electrostatic mechanism built around a simplified version of the Gouy–Chapman theory. We find that the single-walled carbon nanotubes preferentially transported cations and that the cation permeability is size-dependent. The ionic conductance increases as the absolute hydration enthalpy decreases for monovalent cations with similar solid-state radii, hydrated radii, and bulk mobility. Charge screening experiments using either the addition of cationic or anionic polymers, divalent metal cations, or changes in pH reveal the enormous impact of the negatively charged carboxylates at the entrance of the single-walled carbon nanotubes. These observations were modeled in the low-to-medium concentration range (0.1–2.0 M) by an electrostatic mechanism that mimics the behavior observed in many biological ion channel-forming proteins. Moreover, multi-ion conduction in the high concentration range (>2.0 M) further reinforces the similarity between single-walled carbon nanotubes and protein ion channels. PMID:28103039

  20. Single-Walled Carbon Nanotubes: Mimics of Biological Ion Channels.

    PubMed

    Amiri, Hasti; Shepard, Kenneth L; Nuckolls, Colin; Hernández Sánchez, Raúl

    2017-02-08

    Here we report on the ion conductance through individual, small diameter single-walled carbon nanotubes. We find that they are mimics of ion channels found in natural systems. We explore the factors governing the ion selectivity and permeation through single-walled carbon nanotubes by considering an electrostatic mechanism built around a simplified version of the Gouy-Chapman theory. We find that the single-walled carbon nanotubes preferentially transported cations and that the cation permeability is size-dependent. The ionic conductance increases as the absolute hydration enthalpy decreases for monovalent cations with similar solid-state radii, hydrated radii, and bulk mobility. Charge screening experiments using either the addition of cationic or anionic polymers, divalent metal cations, or changes in pH reveal the enormous impact of the negatively charged carboxylates at the entrance of the single-walled carbon nanotubes. These observations were modeled in the low-to-medium concentration range (0.1-2.0 M) by an electrostatic mechanism that mimics the behavior observed in many biological ion channel-forming proteins. Moreover, multi-ion conduction in the high concentration range (>2.0 M) further reinforces the similarity between single-walled carbon nanotubes and protein ion channels.

  1. Optical modulation of single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Strano, Michael S.

    2007-03-01

    Recent advances in the spectroscopy of single walled carbon nanotubes have significantly enhanced our ability to understand and control their surface chemistry, both covalently and non-covalently. Our work has focused on modulating the optical properties of semiconducting single walled carbon nanotubes as near infrared photoluminescent sensors for chemical analysis. Molecular detection using near-infrared 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. In one system, the transition of DNA secondary structure modulates the dielectric environment of the single-walled carbon nanotube (SWNT) around which it is adsorbed. The SWNT band-gap fluorescence undergoes a red shift when an encapsulating 30-nucleotide oligomer is exposed to counter ions that screen the charged backbone. We demonstrate the detection of the mercuric ions in whole blood, tissue, and from within living mammalian cells using this technology. Similar results are obtained for DNA hybridization and the detection of single nucleotide polymorphism. We also report the synthesis and successful testing of near-infrared β-D-glucose sensors2 that utilize a different mechanism: a photoluminescence modulation via charge transfer. The results demonstrate new opportunities for nanoparticle optical sensors that operate in strongly absorbing media of relevance to medicine or biology.

  2. Use of alkali metal salts to prepare high purity single-walled carbon nanotube solutions and thin films

    NASA Astrophysics Data System (ADS)

    Ashour, Rakan F.

    Single-walled carbon nanotubes (SWCNTs) display interesting electronic and optical properties desired for many advanced thin film applications, such as transparent conductive electrodes or thin-film transistors. Large-scale production of SWCNTs generally results in polydispersed mixtures of nanotube structures. Since SWCNT electronic character (conducting or semiconducting nature) depends on the nanotube structure, application performance is being held back by this inability to discretely control SWCNT synthesis. Although a number of post-production techniques are able to separate SWCNTs based on electronic character, diameter, or chirality, most still suffer from the disadvantage of high costs of materials, equipment, or labor intensity to be relevant for large-scale production. On the other hand, chromatographic separation has emerged as a method that is compatible with large scale separation of metallic and semiconducting SWCNTs. In this work, SWCNTs, in an aqueous surfactant suspension of sodium dodecyl sulfate (SDS), are separated by their electronic character using a gel chromatography process. Metallic SWCNTs (m-SWCNTs) are collected as initial fractions since they show minimum interaction with the gel medium, whereas, semiconducting SWCNTs (sc- SWCNTs) remain adsorbed to the gel. The process of sc-SWCNT retention in the gel is found to be driven by the packing density of SDS around the SWCNTs. Through a series of separation experiments, it is shown that sc-SWCNTs can be eluted from the gel simply by disturbing the configuration of the SDS/SWCNT micellar structure. This is achieved by either introducing a solution containing a co-surfactant, such as sodium cholate (SC), or solutions of alkali metal ionic salts. Analysis of SWCNT suspensions by optical absorption provides insights into the effect of changing the metal ion (M+ = Li+, Na+, and K+) in the eluting solution. Salts with smaller metal ions (e.g. Li+) require higher concentrations to achieve

  3. Strain Sensitivity in Single Walled Carbon Nanotubes for Multifunctional Materials

    NASA Technical Reports Server (NTRS)

    Heath, D. M. (Technical Monitor); Smits, Jan M., VI

    2005-01-01

    Single walled carbon nanotubes represent the future of structural aerospace vehicle systems due to their unparalleled strength characteristics and demonstrated multifunctionality. This multifunctionality rises from the CNT's unique capabilities for both metallic and semiconducting electron transport, electron spin polarizability, and band gap modulation under strain. By incorporating the use of electric field alignment and various lithography techniques, a single wall carbon nanotube (SWNT) test bed for measurement of conductivity/strain relationships has been developed. Nanotubes are deposited at specified locations through dielectrophoresis. The circuit is designed such that the central, current carrying section of the nanotube is exposed to enable atomic force microscopy and manipulation in situ while the transport properties of the junction are monitored. By applying this methodology to sensor development a flexible single wall carbon nanotube (SWNT) based strain sensitive device has been developed. Studies of tensile testing of the flexible SWNT device vs conductivity are also presented, demonstrating the feasibility of using single walled HiPCO (high-pressure carbon monoxide) carbon nanotubes as strain sensing agents in a multi-functional materials system.

  4. Electrochemical hydrogen storage in single-walled carbon nanotube paper.

    PubMed

    Guo, Z P; Ng, S H; Wang, J Z; Huang, Z G; Liu, H K; Too, C O; Wallace, G G

    2006-03-01

    Single-walled carbon nanotube (SWNT) papers were successfully prepared by dispersing SWNTs in Triton X-100 solution, then filtered by PVDF membrane (0.22 microm pore size). The electrochemical behavior and the reversible hydrogen storage capacity of single-walled carbon nanotube (SWNT) papers have been investigated in alkaline electrolytic solutions (6 N KOH) by cyclic voltammetry, linear micropolarization, and constant current charge/discharge measurements. The effect of thickness and the addition of carbon black on hydrogen adsorption/desorption were also investigated. It was found that the electrochemical charge-discharge mechanism occurring in SWNT paper electrodes is somewhere between that of carbon nanotubes (physical process) and that of metal hydride electrodes (chemical process), and consists of a charge-transfer reaction (Reduction/Oxidation) and a diffusion step (Diffusion).

  5. Fluidic patch antenna based on liquid metal alloy/single-wall carbon-nanotubes operating at the S-band frequency

    NASA Astrophysics Data System (ADS)

    Aïssa, B.; Nedil, M.; Habib, M. A.; Haddad, E.; Jamroz, W.; Therriault, D.; Coulibaly, Y.; Rosei, F.

    2013-08-01

    This letter describes the fabrication and characterization of a fluidic patch antenna operating at the S-band frequency (4 GHz). The antenna prototype is composed of a nanocomposite material made by a liquid metal alloy (eutectic gallium indium) blended with single-wall carbon-nanotube (SWNTs). The nanocomposite is then enclosed in a polymeric substrate by employing the UV-assisted direct-writing technology. The fluidic antennas specimens feature excellent performances, in perfect agreement with simulations, showing an increase in the electrical conductivity and reflection coefficient with respect to the SWNTs concentration. The effect of the SWNTs on the long-term stability of antenna's mechanical properties is also demonstrated.

  6. Is there a difference in van der Waals interactions between rare gas atoms adsorbed on metallic and semiconducting single-walled carbon nanotubes?

    PubMed

    Chen, De-Li; Mandeltort, Lynn; Saidi, Wissam A; Yates, John T; Cole, Milton W; Johnson, J Karl

    2013-03-29

    The differences in the polarizabilities of metallic (M) and semiconducting (S) single-walled carbon nanotubes (SWNTs) might give rise to differences in adsorption potentials. We show from experiments and van der Waals--corrected density functional theory that the binding energies of Xe adsorbed on M- and S-SWNTs are nearly identical. Temperature programed desorption experiments of Xe on purified M- and S-SWNTs give similar peak temperatures, indicating that desorption kinetics and binding energies are independent of the type of SWNT. Binding energies computed from vdW-corrected density functional theory are in good agreement with experiments.

  7. Is there a Difference in Van Der Waals Interactions between Rare Gas Atoms Adsorbed on Metallic and Semiconducting Single-Walled Carbon Nanotubes?

    SciTech Connect

    Chen, De-Li; Mandeltort, Lynn; Saidi, Wissam A.; Yates, John T.; Cole, Milton W.; Johnson, J. Karl

    2013-03-01

    Differences in polarizabilities of metallic (M) and semiconducting (S) single-walled carbon nanotubes (SWNTs) might give rise to differences in adsorption potentials. We show from experiments and van der Waals-corrected density functional theory (DFT) that binding energies of Xe adsorbed on M- and S-SWNTs are nearly identical. Temperature programmed desorption of Xe on purified M- and S-SWNTs give similar peak temperatures, indicating that desorption kinetics and binding energies are independent of the type of SWNT. Binding energies computed from vdW-corrected DFT are in good agreement with experiments.

  8. Electrochemistry at nanoscale electrodes: individual single-walled carbon nanotubes (SWNTs) and SWNT-templated metal nanowires.

    PubMed

    Dudin, Petr V; Snowden, Michael E; Macpherson, Julie V; Unwin, Patrick R

    2011-12-27

    Individual nanowires (NWs) and native single-walled carbon nanotubes (SWNTs) can be readily used as well-defined nanoscale electrodes (NSEs) for voltammetric analysis. Here, the simple photolithography-free fabrication of submillimeter long Au, Pt, and Pd NWs, with sub-100 nm heights, by templated electrodeposition onto ultralong flow-aligned SWNTs is demonstrated. Both individual Au NWs and SWNTs are employed as NSEs for electron-transfer (ET) kinetic quantification, using cyclic voltammetry (CV), in conjunction with a microcapillary-based electrochemical method. A small capillary with internal diameter in the range 30-70 μm, filled with solution containing a redox-active mediator (FcTMA(+) ((trimethylammonium)methylferrocene), Fe(CN)(6)(4-), or hydrazine) is positioned above the NSE, so that the solution meniscus completes an electrochemical cell. A 3D finite-element model, faithfully reproducing the experimental geometry, is used to both analyze the experimental CVs and derive the rate of heterogeneous ET, using Butler-Volmer kinetics. For a 70 nm height Au NW, intrinsic rate constants, k(0), up to ca. 1 cm s(-1) can be resolved. Using the same experimental configuration the electrochemistry of individual SWNTs can also be accessed. For FcTMA(+/2+) electrolysis the simulated ET kinetic parameters yield very fast ET kinetics (k(0) > 2 ± 1 cm s(-1)). Some deviation between the experimental voltammetry and the idealized model is noted, suggesting that double-layer effects may influence ET at the nanoscale.

  9. Production of carbon single wall nanotubes versus experimental parameters

    NASA Astrophysics Data System (ADS)

    Journet, C.; Micholet, V.; Bernier, P.; Maser, W. K.; Loiseau, A.; Lamy de la Chapelle, M.; Lefrant, S.; Lee, R.; Fischer, J. E.

    1998-08-01

    Bundles of carbon single wall nanotubes (SWNTs) are produced by sublimating selected metal mixtures and carbon in an inert atmosphere during an electric arc [1]. Various experimental parameters such as the nature and relative proportions of metallic catalysts [1] or the kind and pressure of gas can influence the quantity and geometry of bundles produced by the arc process. In this paper, we particularly focus on the role of the nature and pressure of gas used. Systematic studies have been made and we present the results obtained by Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), X-Ray Diffraction (XRD) and High Resolution Raman Spectroscopy (HRRS).

  10. Toxicity of single-walled carbon nanotubes.

    PubMed

    Ong, Li-Chu; Chung, Felicia Fei-Lei; Tan, Yuen-Fen; Leong, Chee-Onn

    2016-01-01

    Carbon nanotubes (CNTs) are an important class of nanomaterials, which have numerous novel properties that make them useful in technology and industry. Generally, there are two types of CNTs: single-walled nanotubes (SWNTs) and multi-walled nanotubes. SWNTs, in particular, possess unique electrical, mechanical, and thermal properties, allowing for a wide range of applications in various fields, including the electronic, computer, aerospace, and biomedical industries. However, the use of SWNTs has come under scrutiny, not only due to their peculiar nanotoxicological profile, but also due to the forecasted increase in SWNT production in the near future. As such, the risk of human exposure is likely to be increased substantially. Yet, our understanding of the toxicological risk of SWNTs in human biology remains limited. This review seeks to examine representative data on the nanotoxicity of SWNTs by first considering how SWNTs are absorbed, distributed, accumulated and excreted in a biological system, and how SWNTs induce organ-specific toxicity in the body. The contradictory findings of numerous studies with regards to the potential hazards of SWNT exposure are discussed in this review. The possible mechanisms and molecular pathways associated with SWNT nanotoxicity in target organs and specific cell types are presented. We hope that this review will stimulate further research into the fundamental aspects of CNTs, especially the biological interactions which arise due to the unique intrinsic characteristics of CNTs.

  11. Improvements in Production of Single-Walled Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Balzano, Leandro; Resasco, Daniel E.

    2009-01-01

    A continuing program of research and development has been directed toward improvement of a prior batch process in which single-walled carbon nanotubes are formed by catalytic disproportionation of carbon monoxide in a fluidized-bed reactor. The overall effect of the improvements has been to make progress toward converting the process from a batch mode to a continuous mode and to scaling of production to larger quantities. Efforts have also been made to optimize associated purification and dispersion post processes to make them effective at large scales and to investigate means of incorporating the purified products into composite materials. The ultimate purpose of the program is to enable the production of high-quality single-walled carbon nanotubes in quantities large enough and at costs low enough to foster the further development of practical applications. The fluidized bed used in this process contains mixed-metal catalyst particles. The choice of the catalyst and the operating conditions is such that the yield of single-walled carbon nanotubes, relative to all forms of carbon (including carbon fibers, multi-walled carbon nanotubes, and graphite) produced in the disproportionation reaction is more than 90 weight percent. After the reaction, the nanotubes are dispersed in various solvents in preparation for end use, which typically involves blending into a plastic, ceramic, or other matrix to form a composite material. Notwithstanding the batch nature of the unmodified prior fluidized-bed process, the fluidized-bed reactor operates in a continuous mode during the process. The operation is almost entirely automated, utilizing mass flow controllers, a control computer running software specific to the process, and other equipment. Moreover, an important inherent advantage of fluidized- bed reactors in general is that solid particles can be added to and removed from fluidized beds during operation. For these reasons, the process and equipment were amenable to

  12. Self-formation of highly aligned metallic, semiconducting and single chiral single-walled carbon nanotubes assemblies via a crystal template method

    SciTech Connect

    Kawai, Hideki; Hasegawa, Kai; Yanagi, Kazuhiro; Oyane, Ayako; Naitoh, Yasuhisa

    2014-09-01

    The fabrication of an aligned array of single-walled carbon nanotubes (SWCNTs) with a single chiral state has been a significant challenge for SWCNT applications as well as for basic science research. Here, we developed a simple, unique technique to produce assemblies in which metallic, semiconducting, and single chiral state SWCNTs were densely and highly aligned. We utilized a crystal of surfactant as a template on which mono-dispersed SWCNTs in solution self-assembled. Micro-Raman measurements and scanning electron microscopy measurements clearly showed that the SWCNTs were highly and densely aligned parallel to the crystal axis, indicating that approximately 70% of the SWCNTs were within 7° of being parallel. Moreover, the assemblies exhibited good field effect transistor characteristics with an on/off ratio of 1.3 × 10{sup 5}.

  13. Comparison of sample digestion techniques for the determination of trace and residual catalyst metal content in single-wall carbon nanotubes by inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Grinberg, Patricia; Sturgeon, Ralph E.; Diehl, Liange de O.; Bizzi, Cezar A.; Flores, Erico M. M.

    2015-03-01

    A single-wall carbon nanotube material produced by laser ablation of renewable biochar in the presence of Ni and Co catalyst was characterized for residual catalyst (Co and Ni) as well as trace metal impurity content (Fe, Mo, Cr, Pb and Hg) by isotope dilution ICP-MS following sample digestion. Several matrix destruction procedures were evaluated, including a multi-step microwave-assisted acid digestion, dry ashing at 450 °C and microwave-induced combustion with oxygen. Results were benchmarked against those derived from neutron activation analysis and also supported by solid sampling continuum source GF-AAS for several of the elements. Although laborious to execute, the multi-step microwave-assisted acid digestion proved to be most reliable for recovery of the majority of the analytes, although content of Cr remained biased low for each approach, likely due to its presence as refractory carbide.

  14. Methods for Gas Sensing with Single-Walled Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B. (Inventor)

    2013-01-01

    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  15. Assembling techniques for micellar dispersed carbon single-walled nanotubes

    NASA Astrophysics Data System (ADS)

    Burghard, M.; Muster, J.; Duesberg, G.; Philipp, G.; Krstic, V.; Roth, S.

    1998-08-01

    Surfactant-stabilised aqueous dispersions of carbon single-walled nanotubes (SWNTs) provide attractive possibilities for different types of assembling processes. The adsorption behaviour of chromatographically purified, micellar suspended SWNTs on silica substrates and metal electrodes is presented. Chemical modifications of the substrate surface allow to control the adsorption kinetics and the fraction between adsorbed individual SWNTs and bundles of SWNTs. Tube alignment occurs presumably due to flow effects upon removal of the surfactant. As a second assembling technique, we describe the preparation of Langmuir-Blodgett films consisting of SWNTs embedded in a surfactant matrix.

  16. Fitting Single-Walled Carbon Nanotube Optical Spectra

    PubMed Central

    2017-01-01

    In this work, a comprehensive methodology for the fitting of single-walled carbon nanotube absorption spectra is presented. Different approaches to background subtraction, choice of line profile, and calculation of full width at half-maximum are discussed both in the context of previous literature and the contemporary understanding of carbon nanotube photophysics. The fitting is improved by the inclusion of exciton–phonon sidebands, and new techniques to improve the individualization of overlapped nanotube spectra by exploiting correlations between the first- and second-order optical transitions and the exciton–phonon sidebands are presented. Consideration of metallic nanotubes allows an analysis of the metallic/semiconducting content, and a process of constraining the fit of highly congested spectra of carbon nanotube solid films according to the spectral weights of each (n, m) species in solution is also presented, allowing for more reliable resolution of overlapping peaks into single (n, m) species contributions. PMID:28393134

  17. Fitting Single-Walled Carbon Nanotube Optical Spectra.

    PubMed

    Pfohl, Moritz; Tune, Daniel D; Graf, Arko; Zaumseil, Jana; Krupke, Ralph; Flavel, Benjamin S

    2017-03-31

    In this work, a comprehensive methodology for the fitting of single-walled carbon nanotube absorption spectra is presented. Different approaches to background subtraction, choice of line profile, and calculation of full width at half-maximum are discussed both in the context of previous literature and the contemporary understanding of carbon nanotube photophysics. The fitting is improved by the inclusion of exciton-phonon sidebands, and new techniques to improve the individualization of overlapped nanotube spectra by exploiting correlations between the first- and second-order optical transitions and the exciton-phonon sidebands are presented. Consideration of metallic nanotubes allows an analysis of the metallic/semiconducting content, and a process of constraining the fit of highly congested spectra of carbon nanotube solid films according to the spectral weights of each (n, m) species in solution is also presented, allowing for more reliable resolution of overlapping peaks into single (n, m) species contributions.

  18. Alignment enhanced photoconductivity in single wall carbon nanotube films.

    PubMed

    Liu, Ye; Lu, Shaoxin; Panchapakesan, Balaji

    2009-01-21

    In this paper we report, for the first time, the alignment enhanced photoconductivity of single wall carbon nanotube films upon laser illumination. The photoconductivity exhibited an increase, decrease or even 'negative' values when the laser spot was on different positions between contact electrodes, showing a 'position' dependent photoconductivity of partially aligned films of carbon nanotubes. Photon induced charge carrier generation in single wall carbon nanotubes and subsequent charge separation across the metal-carbon nanotube contacts is believed to cause the photoconductivity changes. A net photovoltage of approximately 4 mV and a photocurrent of approximately 10 microA were produced under the laser intensity of approximately 273 mW with a quantum efficiency of approximately 7.8% in vacuum. The photocurrent was observed to be in the direction of nanotube alignment. Finally, there was a strong dependence of the polarization of the incident light on the photocurrent and the orientation of the films influenced the dynamics of the rise and fall of the photocurrent. All of these phenomena clearly have significance in the area of design and fabrication of solar cells, micro-opto-mechanical systems and photodetectors based on carbon nanotubes.

  19. Single wall carbon nanotubes: Separation and applications to biosensors

    NASA Astrophysics Data System (ADS)

    Kim, Sang Nyon

    Single wall carbon nanotubes uniquely exhibit one-dimensional quantum confined properties by being either semiconducting (sem-) or metallic (met-) depending on their atomic arrangements. The stochastic nature of SWNT growth renders met-:sem- ratio being 1:2 and diameter range being distributed in 0.4-2nm with a close-packed bundle configuration. For many high-performance devices using SWNTs, acquiring well-separated and/or isolated single-diameter, metallicity and/or chirality nanotubes is greatly in demand. Recently, the bulk separation and/or enrichment of single wall carbon nanotubes (SWNTs) according to type (or otherwise termed "metallicity") and diameter (dt) has become possible. This thesis presents a route to probe mechanisms in diameter and metallicity dependent separation of SWNTs. A systematic analysis tool, that enables the quantitative examination of resonance Raman spectra, is established from nanotube samples that have been separated according to metallicity and d t via an octadecylamine mediated protocol. This protocol uses the relative changes in the integrated intensities of the radial-breathing mode region for the quantitative evaluation. By further establishing the physicochemical properties of charge-stabilized SWNT dispersions in polar aprotic media (i.e. N,N-dimethylformide) a more detailed description of the underlying separation mechanism is given. Here, I use resonance Raman spectroscopy (RRS) as a tool to probe SWNT redox chemistry. The Gibbs free energy, modeled by calculating the charge-loss from the (n,m)-dependent integrated density of states across the corresponding jump in the redox potential, is utilized to support the separation mechanism. Additionally, the evaluation of SWNT forest platforms for amperometric protein immunoassays is presented. Horseradish peroxidase is used as the label and the sensing signals are acquired from electrochemical reduction of hydrogen peroxide. Specific studies on human serum albumin and prostate

  20. Optical properties of single-walled carbon nanotubes highly separated in semiconducting and metallic tubes functionalized with poly(vinylidene fluoride)

    NASA Astrophysics Data System (ADS)

    Matea, A.; Baibarac, M.; Baltog, I.

    2017-02-01

    In this paper, the interaction of poly(vinylidene fluoride) (PVDF) with single-walled carbon nanotubes (SWNTs) highly separated in metallic (M) and semiconducting (S) tubes is studied by resonant Raman scattering and FTIR spectroscopy. In this order, the PVDF/SWNTs membranes were prepared by the evaporation of dimethylformamide (DMF) from PVDF solutions containing i) the as-prepared SWNTs samples, i.e., as mixtures of metallic (33%) and semiconducting (66%) tubes (M + S-SWNTs), ii) SWNTs highly separated in metallic tubes (98%, M-SWNTs), and iii) SWNTs highly separated in semiconducting tubes (99%, S-SWNTs). An increase in the PVDF β phase weight, highlighted by the increase in the absorbance of IR band at 843 cm-1, is reported to take place in the presence of M + S-SWNTs and S-SWNTs. An increase of the PVDF γ crystalline phase weight is reported for the PVDF/M + S-SWNTs, PVDF/M-SWNTs and PVDF/S-SWNTs membranes. Using Raman scattering, a donor-acceptor interaction is invoked to take place at the interface PVDF/M + S-SWNTs and PVDF/S-SWNTs. In the case of the membranes based on PVDF and M-SWNTs, the changes reported in Raman spectra of the two constituents are explained on the base induction-interaction forces between the permanent dipole of PVDF and induced dipole of M-SWNTs.

  1. Structure-Controlled Synthesis of Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Yan

    Single-walled carbon nanotubes (SWNTs) present structure-determined outstanding properties and SWNTs with a single (n, m) type are needed in many advanced applications. However, the chirality-specific growth of SWNTs is always a great challenge. Carbon nanotubes and their caps or catalysts can all act as the structural templates to guide the formation of SWNTs with a specified chirality. SWNT growth via a catalyzed chemical vapor deposition CVD process is normally more efficient and therefore of great interest. We developed a new family of catalyst, tungsten-based intermetallic nanocrystals, to grow SWNTs with specified chiral structures. Such intermetallic nanocrystals present unique structure and atomic arrangements, which are distinctly different from the normal alloy nanoparticles or simple metal nanocrystals, therefore can act as the template to grow SWNTs with designed (n, m) structures. Using W6Co7 catalysts, we realized the selective growth of (12, 6), (16, 0), (14, 4) and other chiralities. By the cooperation of thermodynamic and kinetic factors, SWNTs with high chirality purity can be obtained. . Structure-Controlled Synthesis of Single-Walled Carbon Nanotubes.

  2. Center for Applications of Single-Walled Carbon Nanotubes

    SciTech Connect

    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.

  3. Three-Dimensional Flexible Complementary Metal-Oxide-Semiconductor Logic Circuits Based On Two-Layer Stacks of Single-Walled Carbon Nanotube Networks.

    PubMed

    Zhao, Yudan; Li, Qunqing; Xiao, Xiaoyang; Li, Guanhong; Jin, Yuanhao; Jiang, Kaili; Wang, Jiaping; Fan, Shoushan

    2016-02-23

    We have proposed and fabricated stable and repeatable, flexible, single-walled carbon nanotube (SWCNT) thin film transistor (TFT) complementary metal-oxide-semiconductor (CMOS) integrated circuits based on a three-dimensional (3D) structure. Two layers of SWCNT-TFT devices were stacked, where one layer served as n-type devices and the other one served as p-type devices. On the basis of this method, it is able to save at least half of the area required to construct an inverter and make large-scale and high-density integrated CMOS circuits easier to design and manufacture. The 3D flexible CMOS inverter gain can be as high as 40, and the total noise margin is more than 95%. Moreover, the input and output voltage of the inverter are exactly matched for cascading. 3D flexible CMOS NOR, NAND logic gates, and 15-stage ring oscillators were fabricated on PI substrates with high performance as well. Stable electrical properties of these circuits can be obtained with bending radii as small as 3.16 mm, which shows that such a 3D structure is a reliable architecture and suitable for carbon nanotube electrical applications in complex flexible and wearable electronic devices.

  4. Electromechanical transducers based on single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Stampfer, C.; Jungen, A.; Helbling, T.; Durrer, L.; Hierold, C.

    2008-08-01

    Carbon Nanotubes are intensively studied as a new functional material for nanoelectronics and nano electromechanical systems, including nanosensor devices. Single-walled carbon nanotubes (SWNTs) show unique mechanical and electromechanical properties and they change electronic properties by interacting with the environment (this can be e.g. used for chemical and biochemical sensing). Therefore nanotubes are very promising candidates for active elements in future nanoscaled transducers. Concepts for carbon nanotube sensors for mechanical and chemical detection schemes are presented. We focus on single-walled carbon nanotubes as natural macro molecular functional structures with an option for low scale integration in micro and nano electromechanical systems (MEMS and NEMS).

  5. Laser ablation process for single-walled carbon nanotube production

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram

    2004-01-01

    Different types of lasers are now routinely used to prepare single-walled carbon nanotubes. The original method developed by researchers at Rice University used a "double-pulse laser oven" process. Several researchers have used variations of the lasers to include one-laser pulse (green or infrared), different pulse widths (ns to micros as well as continuous wave), and different laser wavelengths (e.g., CO2, or free electron lasers in the near to far infrared). Some of these variations are tried with different combinations and concentrations of metal catalysts, buffer gases (e.g., helium), oven temperatures, flow conditions, and even different porosities of the graphite targets. This article is an attempt to cover all these variations and their relative merits. Possible growth mechanisms under these different conditions will also be discussed.

  6. Single Wall Carbon Nanotube-Based Structural Health Sensing Materials

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal; Ingram, JoAnne L.; Jordan, Jeffrey D.; Wincheski, Russell A.; Smits, Jan M.; Williams, Phillip A.

    2004-01-01

    Single wall carbon nanotube (SWCNT)-based materials represent the future aerospace vehicle construction material of choice based primarily on predicted strength-to-weight advantages and inherent multifunctionality. The multifunctionality of SWCNTs arises from the ability of the nanotubes to be either metallic or semi-conducting based on their chirality. Furthermore, simply changing the environment around a SWCNT can change its conducting behavior. This phenomenon is being exploited to create sensors capable of measuring several parameters related to vehicle structural health (i.e. strain, pressure, temperature, etc.) The structural health monitor is constructed using conventional electron-beam lithographic and photolithographic techniques to place specific electrode patterns on a surface. SWCNTs are then deposited between the electrodes using a dielectrophoretic alignment technique. Prototypes have been constructed on both silicon and polyimide substrates, demonstrating that surface-mountable and multifunctional devices based on SWCNTs can be realized.

  7. Thermoelectric power of a single-walled carbon nanotubes rope.

    PubMed

    Yu, Fang; Hu, Lijun; Zhou, Haiqing; Qiu, Caiyu; Yang, Huaichao; Chen, Minjiang; Lu, Jianglei; Sun, Lianfeng

    2013-02-01

    In this work, a rope of single-walled carbon nanotubes is prepared by using a diamond wire drawing die. At atmospheric condition, the electrical conductance and the thermoelectric voltage of single-walled carbon nanotubes rope have been investigated with the hot-side temperature ranging from 292 to 380 K, and cold-side temperature at 292 K. For different temperatures in the range of 292 to 380 K at hot-side, the current-voltage curves are almost parallel to each other, indicating that the electrical conductance does not change. The dynamic characteristics of voltage at positive, zero and negative current bias demonstrate that a thermoelectric voltage is induced with a direction from hot- to cold-side. The induced thermoelectric voltage shows linear dependence on the temperature difference between hot- and cold-side. The thermoelectric power of single-walled carbon nanotubes rope is found to be positive and has a value about 17.8 +/- 1.0 microV/K. This result suggests the hole-like carriers in single-walled carbon nanotubes rope. This study will pave the way for single-walled carbon nanotubes based thermoelectric devices.

  8. Role of pH controlled DNA secondary structures in the reversible dispersion/precipitation and separation of metallic and semiconducting single-walled carbon nanotubes.

    PubMed

    Maji, Basudeb; Samanta, Suman K; Bhattacharya, Santanu

    2014-04-07

    Single-stranded DNA (ss-DNA) oligomers (dA20, d[(C3TA2)3C3] or dT20) are able to disperse single-walled carbon nanotubes (SWNTs) in water at pH 7 through non-covalent wrapping on the nanotube surface. At lower pH, an alteration of the DNA secondary structure leads to precipitation of the SWNTs from the dispersion. The structural change of dA20 takes place from the single-stranded to the A-motif form at pH 3.5 while in case of d[(C3TA2)3C3] the change occurs from the single-stranded to the i-motif form at pH 5. Due to this structural change, the DNA is no longer able to bind the nanotube and hence the SWNT precipitates from its well-dispersed state. However, this could be reversed on restoring the pH to 7, where the DNA again relaxes in the single-stranded form. In this way the dispersion and precipitation process could be repeated over and over again. Variable temperature UV-Vis-NIR and CD spectroscopy studies showed that the DNA-SWNT complexes were thermally stable even at ∼90 °C at pH 7. Broadband NIR laser (1064 nm) irradiation also demonstrated the stability of the DNA-SWNT complex against local heating introduced through excitation of the carbon nanotubes. Electrophoretic mobility shift assay confirmed the formation of a stable DNA-SWNT complex at pH 7 and also the generation of DNA secondary structures (A/i-motif) upon acidification. The interactions of ss-DNA with SWNTs cause debundling of the nanotubes from its assembly. Selective affinity of the semiconducting SWNTs towards DNA than the metallic ones enables separation of the two as evident from spectroscopic as well as electrical conductivity studies.

  9. Purification Procedures for Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Gorelik, Olga P.; Nikolaev, Pavel; Arepalli, Sivaram

    2001-01-01

    This report summarizes the comparison of a variety of procedures used to purify carbon nanotubes. Carbon nanotube material is produced by the arc process and laser oven process. Most of the procedures are tested using laser-grown, single-wall nanotube (SWNT) material. The material is characterized at each step of the purification procedures by using different techniques including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Raman, X-ray diffractometry (XRD), thermogravimetric analysis (TGA), nuclear magnetic resonance (NMR), and high-performance liquid chromatography (HPLC). The identified impurities are amorphous and graphitic carbon, catalyst particle aggregates, fullerenes, and hydrocarbons. Solvent extraction and low-temperature annealing are used to reduce the amount of volatile hydrocarbons and dissolve fullerenes. Metal catalysts and amorphous as well as graphitic carbon are oxidized by reflux in acids including HCl, HNO3 and HF and other oxidizers such as H2O2. High-temperature annealing in vacuum and in inert atmosphere helps to improve the quality of SWNTs by increasing crystallinity and reducing intercalation.

  10. Electrical characterization of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Berliocchi, Marco; Brunetti, Francesca; Di Carlo, Aldo; Lugli, Paolo; Orlanducci, Silvia; Terranova, Maria Letizia

    2003-04-01

    Single Wall Carbon Nanotubes (SWCNTs) based nanotechnology appears to be promising for future nanoelectronics. The SWCNT may be either metallic or semiconducting and both metallic and semiconducting types of SWCNTs have been observed experimentally. This gives rise to intriguing possibilities to put together semiconductor-semiconductor and semiconductor-metal junctions for diodes and transistors. The potential for nanotubes in nanoelectronics devices, displays and nanosensors is enormous. However, in order to realize the potential of SWCNTs, it is critical to understand the properties of charge transport and to control phase purity, elicity and arrangement according to specific architectures. We have investigated the electrical properties of various SWCNTs samples whit different organization: bundles of SWCNTs, SWCNT fibres and different membranes and tablets obtained using SWCNTs purified and characterized. Electrical characterizations were carried out by a 4155B Agilent Semiconductor Parameter Analyser. In order to give a mechanical stability to SWCNTs fibres and bundles we have used a nafion matrix coating, so an electrical characterization has been performed on samples with and without this layer. I-V measurements were performed in vacuum and in air using aluminium interdigitated coplanar-electrodes (width=20mm or 40mm) on glass substrates. The behaviour observed is generally supralinear with currents of the order of mA in vacuum and lower values in air with the exception of the tablet samples where the behaviour is ohmic, the currents are higher and similar values of current are detected in air and vacuum.

  11. A first-principle study of one-dimensional carbon atomic chain inserted single-wall carbon nanotubes.

    PubMed

    Mao, Yuliang; Zhong, JianXin; Yuan, JianMei; Zhao, Xinluo; Ando, Yoshinori

    2006-05-01

    Using first principles calculations, we investigate the atomic and electronic structure of carbon nanowires (CNWs) as the carbon chain inserted into single wall carbon nanotubes (SWCNTs). It indicates that the (5,5) CNW system exhibits metallic character, however, the insertion of carbon chain can transit a semi-conducting (9,0) SWCNT into a metallic.

  12. Purity Evaluation of Bulk Single Wall Carbon Nanotube Materials

    NASA Astrophysics Data System (ADS)

    Dettlaff-Weglikowska, U.; Wang, J.; Liang, J.; Hornbostel, B.; Cech, J.; Roth, S.

    2005-09-01

    We report on our experience using a preliminary protocol for quality control of bulk single wall carbon nanotube (SWNT) materials produced by the electric arc-discharge and laser ablation method. The first step in the characterization of the bulk material is mechanical homogenization. Quantitative evaluation of purity has been performed using a previously reported procedure based on solution phase near-infrared spectroscopy. Our results confirm that this method is reliable in determining the nanotube content in the arc-discharge sample containing carbonaceous impurities (amorphous carbon and graphitic particles). However, the application of this method to laser ablation samples gives a relative purity value over 100 %. The possible reason for that might be different extinction coefficient meaning different oscillator strength of the laser ablation tubes. At the present time, a 100 % pure reference sample of laser ablation SWNT is not available, so we chose to adopt the sample showing the highest purity as a new reference sample for a quantitative purity evaluation of laser ablation materials. The graphitic part of the carbonaceous impurities has been estimated using X-ray diffraction of 1:1 mixture of nanotube material and C60 as an internal reference. To evaluate the metallic impurities in the as prepared and homogenized carbon nanotube soot inductive coupled plasma (ICP) has been used.

  13. Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hadjiev, V. G.; Arepalli, S.; Nikolaev, P.; Jandl, S.; Yowell, L.

    2003-01-01

    We explore Raman microprobe capabilities to visualize single wall carbon nanotubes (SWCNTs). Although this technique is limited to a micron scale, we demonstrate that images of individual SWCNTs, bundles or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman response from carbon vibrations in SWCNTs excited by confocal scanning of a focused laser beam. Carbon vibrations reveal key characteristics of SWCNTs as nanotube diameter distribution (radial breathing modes, RBM, 100-300 cm(exp -1)), presence of defects and functional groups (D-mode, 1300-1350 cm(exp -1)), strain and oxidation states of SWCNTs, as well as metallic or semiconducting character of the tubes encoded in the lineshape of the G-modes at 1520-1600 cm(exp - 1). In addition, SWCNTs are highly anisotropic scatterers. The Raman response from a SWCNT is maximal for incident light polarization parallel to the tube axis and vanishing for perpendicular directions. We show that the SWCNT bundle shape or direction can be determined, with some limitations, from a set of Raman images taken at two orthogonal directions of the incident light polarization.

  14. Chemical Sensing with Polyaniline Coated Single-Walled Carbon Nanotubes

    SciTech Connect

    Ding, Mengning; Tang, Yifan; Gou, Pingping; Reber, Michael J; Star, Alexander

    2011-01-25

    Single-walled carbon nanotube/polyaniline (SWNT/PAni) nanocomposite with controlled core/shell morphology was synthesized by a noncovalent functionalization approach. Unique electron interactions between the SWNT core and the PAni shell were studied electrochemically and spectroscopically, and superior sensor performance to chemical gases and vapors was demonstrated.

  15. A Computational Experiment on Single-Walled Carbon Nanotubes

    ERIC Educational Resources Information Center

    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…

  16. Thermogravimetric Analysis of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivram; Nikolaev, Pavel; Gorelik, Olga

    2010-01-01

    An improved protocol for thermogravimetric analysis (TGA) of samples of single-wall carbon nanotube (SWCNT) material has been developed to increase the degree of consistency among results so that meaningful comparisons can be made among different samples. This improved TGA protocol is suitable for incorporation into the protocol for characterization of carbon nanotube material. In most cases, TGA of carbon nanotube materials is performed in gas mixtures that contain oxygen at various concentrations. The improved protocol is summarized.

  17. Comparison of influence of incorporated 3d-, 4d- and 4f-metal chlorides on electronic properties of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kharlamova, M. V.

    2013-06-01

    In the present work, the channels of single-walled carbon nanotubes were filled with melts of ZnCl2, CdCl2, and TbCl3 by a capillary method with subsequent slow cooling. The detailed study of electronic structure of filled nanotubes was performed using Raman, optical absorption, and X-ray photoelectron spectroscopy. The obtained data are in mutual agreement and it proves that the filling of carbon nanotube channels with all these salts leads to the charge transfer from nanotube walls to the incorporated compounds, thus acceptor doping of nanotubes takes place. It was found out that encapsulated terbium chloride has the largest influence on the electronic properties of carbon nanotubes.

  18. Chirality Characterization of Dispersed Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    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.

  19. Purification and fractionation of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Scheibe, Blazej; Borowiak-Palen, Ewa; Kalenczuk, Ryszard J.

    2011-11-01

    This study presents the approach to the purification and subsequent metallic/semiconductive (M/S) fractionation of single-walled carbon nanotubes (SWCNTs) with diameter from 1.04 to 1.60 nm produced via laser ablation. SWCNTs were purified through 3-fold refluxing processes in nitric acid followed by the multiple washings with sodium hydroxide and hydrochloric acid. The purified-annealed SWCNTs sample was divided into seven batches. One batch was dispersed in acetone as a reference sample. Each of the remaining batches were dispersed in one of the following surface agents: sodium dodecyl sulfate, sodium cholate acid (SCA), sodium deoxycholate, cetrimonium bromide, cetylpyridinium chloride, and benzalkonium chloride (BKC). SWCNT suspensions were fractionated via free solution electrophoresis technique. The recovered fractions from electrode and control areas were analyzed via optical absorption spectroscopy in UV-Vis-NIR range to evaluate the efficiency of the separation process. Raman spectroscopy was applied to analyze the purity of the samples. The catalyst content was estimated by atomic absorption spectroscopy. The morphology of the investigated samples was observed via high-resolution transmission electron microscopy. This contribution clearly shows that among the investigated surfactants there are two promising candidates (SCA and BKC) which can efficiently enrich the bulk sample in one electronic type of carbon nanotubes when FSE is applied.

  20. Phase breaking in three-terminal contacted single-walled carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Krstić, V.; Roth, S.; Burghard, M.

    2000-12-01

    The three-terminal electrical transport through single-walled carbon nanotube bundles with low resistive metal contacts is investigated at room temperature. After correcting for the lead resistance, two-probe resistances close to the value expected for a metallic single-walled carbon nanotube are found. Analysis of the experimental data in the frame of the Landauer-Büttiker formalism reveals the phase- and momentum-randomizing effect of the third electrode, which is at floating potential, on the quasiballistic transport. Within this model, the phase-coherence length of the charge carriers is estimated to be ~300 nm at room temperature.

  1. Thermionic Emission of Single-Wall Carbon Nanotubes Measured

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Krainsky, Isay L.; Bailey, Sheila G.; Elich, Jeffrey M.; Landi, Brian J.; Gennett, Thomas; Raffaelle, Ryne P.

    2004-01-01

    Researchers at the NASA Glenn Research Center, in collaboration with the Rochester Institute of Technology, have investigated the thermionic properties of high-purity, single-wall carbon nanotubes (SWNTs) for use as electron-emitting electrodes. Carbon nanotubes are a recently discovered material made from carbon atoms bonded into nanometer-scale hollow tubes. Such nanotubes have remarkable properties. An extremely high aspect ratio, as well as unique mechanical and electronic properties, make single-wall nanotubes ideal for use in a vast array of applications. Carbon nanotubes typically have diameters on the order of 1 to 2 nm. As a result, the ends have a small radius of curvature. It is these characteristics, therefore, that indicate they might be excellent potential candidates for both thermionic and field emission.

  2. Production of single-walled carbon nanotube grids

    DOEpatents

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

    2013-12-03

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

  3. Spectroscopy-Based Characterization of Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Namkung, Juock S.; Wincheski, Russell A.; Seo, J.; Park, Cheol

    2003-01-01

    We present the initial results of our combined investigation of Raman scattering and optical absorption spectroscopy in a batch of single wall carbon nanotubes (SWNTs). The SWNT diameters are first estimated from the four radial breathing mode (RBM) peaks using a simple relation of omega(sub RBM) = 248/cm nm/d(sub t)(nm). The calculated diameter values are related to the optical absorption peaks through the expressions of first interband transition energies, i.e., E(sup S)(sub 11) = 2a gamma/d(sub t) for semiconducting and E(sup S)(sub 11) = 6a gamma/d(sub t) for metallic SWNTs, respectively, where a is the carbon-carbon bond length (0.144 nm) and gamma is the energy of overlapping electrons from nearest neighbor atoms, which is 2.9 eV for a SWNT. This analysis indicates that three RBM peaks are from semiconducting tubes, and the remaining one is from metallic tubes. The detailed analysis in the present study is focused on these three peaks of the first absorption band by determining the values of the representative (n,m) pairs. The first step of analysis is to construct a list of possible (n,m) pairs from the diameters calculated from the positions of the RBM peaks. The second step is to compute the first interband transition energy, E(sub 11), by substituting the constructed list of (n,m) into the expression of Reich and Thomsen, and Saito et al. Finally, the pairs with the energies closest to the experimental values are selected.

  4. Role of pH controlled DNA secondary structures in the reversible dispersion/precipitation and separation of metallic and semiconducting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Maji, Basudeb; Samanta, Suman K.; Bhattacharya, Santanu

    2014-03-01

    Single-stranded DNA (ss-DNA) oligomers (dA20, d[(C3TA2)3C3] or dT20) are able to disperse single-walled carbon nanotubes (SWNTs) in water at pH 7 through non-covalent wrapping on the nanotube surface. At lower pH, an alteration of the DNA secondary structure leads to precipitation of the SWNTs from the dispersion. The structural change of dA20 takes place from the single-stranded to the A-motif form at pH 3.5 while in case of d[(C3TA2)3C3] the change occurs from the single-stranded to the i-motif form at pH 5. Due to this structural change, the DNA is no longer able to bind the nanotube and hence the SWNT precipitates from its well-dispersed state. However, this could be reversed on restoring the pH to 7, where the DNA again relaxes in the single-stranded form. In this way the dispersion and precipitation process could be repeated over and over again. Variable temperature UV-Vis-NIR and CD spectroscopy studies showed that the DNA-SWNT complexes were thermally stable even at ~90 °C at pH 7. Broadband NIR laser (1064 nm) irradiation also demonstrated the stability of the DNA-SWNT complex against local heating introduced through excitation of the carbon nanotubes. Electrophoretic mobility shift assay confirmed the formation of a stable DNA-SWNT complex at pH 7 and also the generation of DNA secondary structures (A/i-motif) upon acidification. The interactions of ss-DNA with SWNTs cause debundling of the nanotubes from its assembly. Selective affinity of the semiconducting SWNTs towards DNA than the metallic ones enables separation of the two as evident from spectroscopic as well as electrical conductivity studies.Single-stranded DNA (ss-DNA) oligomers (dA20, d[(C3TA2)3C3] or dT20) are able to disperse single-walled carbon nanotubes (SWNTs) in water at pH 7 through non-covalent wrapping on the nanotube surface. At lower pH, an alteration of the DNA secondary structure leads to precipitation of the SWNTs from the dispersion. The structural change of dA20 takes place

  5. Assessing the pulmonary toxicity of single-walled carbon nanohorns

    SciTech Connect

    Lynch, Rachel M; Voy, Brynn H; Glass-Mattie, Dana F; Mahurin, Shannon Mark; Saxton, Arnold; Donnel, Robert L.; Cheng, Mengdawn

    2007-01-01

    Previous studies have suggested that single-walled carbon nanotubes (SWCNTs) may pose a pulmonary hazard. We investigated the pulmonary toxicity of single-walled carbon nanohorns (SWCNHs), a relatively new carbon-based nanomaterial that is structurally similar to SWCNTs. Mice were exposed to 30 {micro}g of surfactant-suspended SWCNHs or an equal volume of vehicle control by pharyngeal aspiration and sacrificed 24 hours or 7 days post-exposure. Total and differential cell counts and cytokine analysis of bronchoalveolar lavage fluid demonstrated a mild inflammatory response which was mitigated by day 7 post-exposure. Whole lung microarray analysis demonstrated that SWCNH-exposure did not lead to robust changes in gene expression. Finally, histological analysis showed no evidence of granuloma formation or fibrosis following SWCNH aspiration. These combined results suggest that SWCNH is a relatively innocuous nanomaterial when delivered to mice in vivo using aspiration as a delivery mechanism.

  6. Assessing the pulmonary toxicity of single-walled carbon nanohorns

    SciTech Connect

    Lynch, Rachel M; Voy, Brynn H; Glass-Mattie, Dana F; Mahurin, Shannon Mark; Saxton, Arnold; Donnel, Robert L.; Cheng, Mengdawn

    2007-01-01

    Previous studies have suggested that single-walled carbon nanotubes (SWCNTs) may be pose a pulmonary hazard. We investigated the pulmonary toxicity of single-walled carbon nanohorns (SWCNHs), a relatively new carbon-based nanomaterial that is structurally similar to SWCNTs. Mice were exposed to 30 g of surfactant-suspended SWCNHs by pharyngeal aspiration and sacrificed 24 hours or 7 days post exposure. Total and differential cell counts and cytokine analysis of bronchoalveolar lavage fluid demonstrated a mild inflammatory response which was mitigated by day 7 post exposure. Whole lung microarray analysis demonstrated that SWCNH-exposure did not lead to robust changes in gene expression. Finally, histological analysis showed no evidence of granuloma formation or fibrosis following SWCNH aspiration. These combined results suggest that SWCNH is a relatively innocuous nanomaterial when delivered to mice in vivo using aspiration as a delivery mechanism.

  7. Synthesis, assembly, and applications of single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Ryu, Koungmin

    This dissertation presents the synthesis and assembly of aligned carbon nanotubes, and their applications in both nano-electronics such as transistor and integrated circuits and macro-electronics in energy conversion devices as transparent conducting electrodes. Also, the high performance chemical sensor using metal oxide nanowire has been demonstrated. Chapter 1 presents a brief introduction of carbon nanotube, followed by discussion of a new synthesis technique using nanosphere lithography to grow highly aligned single-walled carbon nanotubes atop quartz and sapphire substrates. This method offers great potential to produce carbon nanotube arrays with simultaneous control over the nanotube orientation, position, density, diameter and even chirality. Chapter 3 introduces the wafer-scale integration and assembly of aligned carbon nanotubes, including full-wafer scale synthesis and transfer of massively aligned carbon nanotube arrays, and nanotube device fabrication on 4 inch Si/SiO2 wafer to yield submicron channel transistors with high on-current density ˜ 20 muA/mum and good on/off ratio and CMOS integrated circuits. In addition, various chemical doping methods for n-type nanotube transistors are studied to fabricate CMOS integrated nanotube circuits such as inverter, NAND and NOR logic devices. Furthermore, defect-tolerant circuit design for NAND and NOR is proposed and demonstrated to guarantee the correct operation of logic circuit, regardless of the presence of mis-aligned or mis-positioned nanotubes. Carbon nanotube flexible electronics and smart textiles for ubiquitous computing and sensing are demonstrated in chapter 4. A facile transfer printing technique has been introduced to transfer massively aligned single-walled carbon nanotubes from the original sapphire/quartz substrates to virtually any other substrates, including glass, silicon, polymer sheets, and even fabrics. The characterization of transferred nanotubes reveals that the transferred

  8. Sorting centimetre-long single-walled carbon nanotubes

    PubMed Central

    Yu, Woo Jong; Chae, Sang Hoon; Vu, Quoc An; Lee, Young Hee

    2016-01-01

    While several approaches have been developed for sorting metallic (m) or semiconducting (s) single-walled carbon nanotubes (SWCNTs), the length of SWCNTs is limited within a micrometer, which restricts excellent electrical performances of SWCNTs for macro-scale applications. Here, we demonstrate a simple sorting method of centimetre-long aligned m- and s-SWCNTs. Ni particles were selectively and uniformly coated along the 1-cm-long m-SWCNTs by applying positive gate bias during electrochemical deposition with continuous electrolyte injection. To sort s-SWCNTs, the Ni coating was oxidized to form insulator outer for blocking of current flow through inner m-SWCNTs. Sorting of m-SWCNTs were demonstrated by selective etching of s-SWCNTs via oxygen plasma, while the protected m-SWCNTs by Ni coating remained intact. The series of source-drain pairs were patterned along the 1-cm-long sorted SWCNTs, which confirmed high on/off ratio of 104–108 for s-SWCNTs and nearly 1 for m-SWCNTs. PMID:27476909

  9. Sorting centimetre-long single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yu, Woo Jong; Chae, Sang Hoon; Vu, Quoc An; Lee, Young Hee

    2016-08-01

    While several approaches have been developed for sorting metallic (m) or semiconducting (s) single-walled carbon nanotubes (SWCNTs), the length of SWCNTs is limited within a micrometer, which restricts excellent electrical performances of SWCNTs for macro-scale applications. Here, we demonstrate a simple sorting method of centimetre-long aligned m- and s-SWCNTs. Ni particles were selectively and uniformly coated along the 1-cm-long m-SWCNTs by applying positive gate bias during electrochemical deposition with continuous electrolyte injection. To sort s-SWCNTs, the Ni coating was oxidized to form insulator outer for blocking of current flow through inner m-SWCNTs. Sorting of m-SWCNTs were demonstrated by selective etching of s-SWCNTs via oxygen plasma, while the protected m-SWCNTs by Ni coating remained intact. The series of source-drain pairs were patterned along the 1-cm-long sorted SWCNTs, which confirmed high on/off ratio of 104–108 for s-SWCNTs and nearly 1 for m-SWCNTs.

  10. Length-dependent extraction of single-walled carbon nanotubes.

    PubMed

    Ziegler, Kirk J; Schmidt, Daniel J; Rauwald, Urs; Shah, Kunal N; Flor, Erica L; Hauge, Robert H; Smalley, Richard E

    2005-12-01

    A two-phase liquid-liquid extraction process is presented which is capable of extracting water-soluble single-walled carbon nanotubes into an organic phase. The extraction utilizes electrostatic interactions between a common phase transfer agent and the sidewall functional groups on the nanotubes. Large length-dependent van der Waals forces for nanotubes allow the ability to control the length of nanotubes extracted into the organic phase as demonstrated by atomic force microscopy.

  11. Titanium dioxide, single-walled carbon nanotube composites

    DOEpatents

    Yao, Yuan; Li, Gonghu; Gray, Kimberly; Lueptow, Richard M.

    2015-07-14

    The present invention provides titanium dioxide/single-walled carbon nanotube composites (TiO.sub.2/SWCNTs), articles of manufacture, and methods of making and using such composites. In certain embodiments, the present invention provides membrane filters and ceramic articles that are coated with TiO.sub.2/SWCNT composite material. In other embodiments, the present invention provides methods of using TiO.sub.2/SWCNT composite material to purify a sample, such as a water or air sample.

  12. Modified Single-Wall Carbon Nanotubes for Reinforce Thermoplastic Polyimide

    NASA Technical Reports Server (NTRS)

    Lebron-COlon, Marisabel; Meador, Michael A.

    2006-01-01

    A significant improvement in the mechanical properties of the thermoplastic polyimide film was obtained by the addition of noncovalently functionalized single-wall carbon nanotubes (SWNTs). Polyimide films were reinforced using pristine SWNTs and functionalized SWNTs (F-SWNTs). The tensile strengths of the polyimide films containing F-SWNTs were found to be approximately 1.4 times higher than those prepared from pristine SWNTs.

  13. Fluctuation theory of single-walled carbon nanotube formation

    NASA Astrophysics Data System (ADS)

    Vosel, Sergey V.; Onischuk, Andrei A.; Purtov, Peter A.; Nasibulin, Albert G.

    2013-11-01

    In the framework of classical fluctuation theory an analytical formula is derived for the reversible work of formation of just detached carbon cap on the surface of catalyst nanoparticle (NP). This cap is considered as single walled carbon nanotube (SWCNT) formation center. The work of cap formation depends on the source carbon chemical potential μC. Using the derived formula for this work an expression for the rate of SWCNT formation is determined. From this expression the SWCNT diameter distributions can be obtained. The obtained distributions have sharp maxima. It is found that the modal SWCNT diameter dm increases weakly with μC being in the narrow window of 1.0 < dm < 1.8 nm when changing the source carbon chemical potential in a wide range. The determined diameter distributions proved to be in a good agreement with the typical values of the SWCNT diameters as experimentally measured in the chemical vapor deposition process. The increase of dm is accompanied by the increase of the distribution width Δd. The selectivity dm/Δd is a function of μC, the higher values of μC the worse selectivity is observed. Although the value of the SWCNT formation rate I cannot be calculated precisely the relationship between I and the system parameters, such as the NP radius RS, can be obtained. This relationship is derived for the solid-liquid-solid system. To determine the function I(RS) for nanotubes of a certain diameter d, formulas for catalyst/amorphous carbon mutual solubilities as functions of NP radius are derived in the framework of the rigorous Gibbs theory of interface. Using the derived formulas an expression giving the dependence I(RS) is obtained. The expression predicts an increase of I with the radius RS. The estimations carried out for the metal/carbon interface surface tension of 1000 mN/m show that the SWCNT formation rate increases by a few orders of magnitude with the radius increase from 1 to 10 nm.

  14. Effects of single-walled carbon nanotubes on lysozyme gelation.

    PubMed

    Tardani, Franco; La Mesa, Camillo

    2014-09-01

    The possibility to disperse carbon nanotubes in biocompatible matrices has got substantial interest from the scientific community. Along this research line, the inclusion of single walled carbon nanotubes in lysozyme-based hydrogels was investigated. Experiments were performed at different nanotube/lysozyme weight ratios. Carbon nanotubes were dispersed in protein solutions, in conditions suitable for thermal gelation. The state of the dispersions was determined before and after thermal treatment. Rheology, dynamic light scattering and different microscopies investigated the effect that carbon nanotubes exert on gelation. The gelation kinetics and changes in gelation temperature were determined. The effect of carbon and lysozyme content on the gel properties was, therefore, determined. At fixed lysozyme content, moderate amounts of carbon nanotubes do not disturb the properties of hydrogel composites. At moderately high volume fractions in carbon nanotubes, the gels become continuous in both lysozyme and nanotubes. This is because percolating networks are presumably formed. Support to the above statements comes by rheology.

  15. Dielectrophoretic manipulation of fluorescing single-walled carbon nanotubes.

    PubMed

    Mureau, Natacha; Mendoza, Ernest; Silva, S Ravi P

    2007-05-01

    We investigate the behavior of fluorescing single-walled carbon nanotubes (SWCNTs) under dielectrophoretic conditions and demonstrate their collection with fluorescence microscopy. SWCNTs are dispersed in water with the aid of a nonionic surfactant, Triton X-100, and labeled through noncovalent binding with the dye 3,3'-dihexyloxacarbocyanine iodide (diOC(6)). The chromophore's affinity to the SWCNTs is due to pi-stacking interactions. Carbon nanotube (CNT) localization is clearly identified on the fluorescence images, showing that the nanotubes concentrate between the electrodes and align along the electric field lines.

  16. Growth of semiconducting single-wall carbon nanotubes with a narrow band-gap distribution

    PubMed Central

    Zhang, Feng; Hou, Peng-Xiang; Liu, Chang; Wang, Bing-Wei; Jiang, Hua; Chen, Mao-Lin; Sun, Dong-Ming; Li, Jin-Cheng; Cong, Hong-Tao; Kauppinen, Esko I.; Cheng, Hui-Ming

    2016-01-01

    The growth of high-quality semiconducting single-wall carbon nanotubes with a narrow band-gap distribution is crucial for the fabrication of high-performance electronic devices. However, the single-wall carbon nanotubes grown from traditional metal catalysts usually have diversified structures and properties. Here we design and prepare an acorn-like, partially carbon-coated cobalt nanoparticle catalyst with a uniform size and structure by the thermal reduction of a [Co(CN)6]3− precursor adsorbed on a self-assembled block copolymer nanodomain. The inner cobalt nanoparticle functions as active catalytic phase for carbon nanotube growth, whereas the outer carbon layer prevents the aggregation of cobalt nanoparticles and ensures a perpendicular growth mode. The grown single-wall carbon nanotubes have a very narrow diameter distribution centred at 1.7 nm and a high semiconducting content of >95%. These semiconducting single-wall carbon nanotubes have a very small band-gap difference of ∼0.08 eV and show excellent thin-film transistor performance. PMID:27025784

  17. Aligned arrays of single walled carbon nanotubes for transparent electronics

    NASA Astrophysics Data System (ADS)

    Du, Frank; Rogers, John A.

    2013-06-01

    Single walled carbon nanotubes have garnered substantial interest in the electronic materials research community due to their unparalleled intrinsic electrical properties. In addition, their mechanical robustness and thin geometries make SWNTs ideal candidates for transparent electronics. Aligned arrays of SWNTs grown via chemical vapor deposition (CVD) on quartz enable device uniformity and wafer scale integration with existing commercial semiconductor processing methods. A crucial roadblock in incorporation of SWNTs in commercial electronics has been the co-existence of metallic and semiconducting SWNTs. Demanding device metrics in high performance and complex integrated electrical devices, sensors, and other applications dictate the necessity of pristine, purely semiconducting arrays of SWNTs. By exploiting a novel process in nanoscale flow of thin film organic coatings, we have demonstrated a method to purify as-grown aligned arrays to produce such as result. Comparison with single nanotube statistics, characterization using a novel thermal scanning probe microscopy technique, as well as corroboration with thermal modeling validated the result. Thin film field effect transistors exhibiting mobilities exceeding ~1000cm2/Vs and on/off ratios exceeding 10,000 were fabricated using the purified semiconducting SWNTs. This manuscript reviews some of these results, which represent the first successful demonstration of purification of aligned arrays of SWNTs, in a robust and scalable scheme that allows integration of aligned arrays into complex, high performance electrical devices. We separately also describe new results on the advanced development of soft lithography techniques with the ability to transfer print aligned arrays of SWNTs onto transparent substrates after synthesis and processing, thereby completing a direct pathway to achieve complex, high performance, and highly integrated transparent SWNTs electronics, sensors, or other devices.

  18. Charging and defects in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Nguyen, Khoi Thi

    2011-12-01

    Single-Walled Carbon Nanotubes (SWCNTs) have been one of the most intensively studied materials. Because of their single-atomic-layer structure, SWCNTs are extremely sensitive to environmental interactions, in which charge transfer and defect formation are the most notable effects. Among a number of microscopic and spectroscopic methods, Raman spectroscopy is a widely used technique to characterize physics and chemistry of CNTs. By utilizing simultaneous Raman and electron transport measurements along with polymer electrolyte gating, this dissertation focuses on studying charging and defects in SWCNTs at single nanotube level and in single layer graphene, the building block of SWCNTs. By controllably charging metallic SWCNTs (m-CNTs), the intrinsic nature of the broad and asymmetric Fano lineshape in Raman G band of m-CNTs was first time evidenced. The observation that Fano component is most broadened and downshifted when Fermi level is close to the Dirac point (DP) reveals its origin as the consequence of coupling of phonon to vertical electronic transitions. Furthermore, we have systematically introduced covalent defects to m-CNTs to study how phonon softening and electrical characteristics are affected by disorders. In addition to decreasing electrical conductance with increasing on/off current ratio eventually leading to semiconducting behavior, adding covalent defects reduces the degree of softening and broadening of longitudinal optical (LO) phonon mode but enhances the softening of transverse optical (TO) mode of the G-band near the DP. Charging and defect effects in semiconducting SWCNTs and single layer graphene, a closely related material to SWCNTs, have also been discussed.

  19. 40 CFR 721.10156 - Single-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Single-walled carbon nanotubes... Specific Chemical Substances § 721.10156 Single-walled carbon nanotubes (generic). (a) Chemical substance... single-walled carbon nanotubes (PMN P-08-328) is subject to reporting under this section for...

  20. 40 CFR 721.10156 - Single-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Single-walled carbon nanotubes... Specific Chemical Substances § 721.10156 Single-walled carbon nanotubes (generic). (a) Chemical substance... single-walled carbon nanotubes (PMN P-08-328) is subject to reporting under this section for...

  1. 40 CFR 721.10156 - Single-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Single-walled carbon nanotubes... Specific Chemical Substances § 721.10156 Single-walled carbon nanotubes (generic). (a) Chemical substance... single-walled carbon nanotubes (PMN P-08-328) is subject to reporting under this section for...

  2. 40 CFR 721.10156 - Single-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Single-walled carbon nanotubes... Specific Chemical Substances § 721.10156 Single-walled carbon nanotubes (generic). (a) Chemical substance... single-walled carbon nanotubes (PMN P-08-328) is subject to reporting under this section for...

  3. Chaotic region of elastically restrained single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hu, Weipeng; Song, Mingzhe; Deng, Zichen; Zou, Hailin; Wei, Bingqing

    2017-02-01

    The occurrence of chaos in the transverse oscillation of the carbon nanotube in all of the precise micro-nano mechanical systems has a strong impact on the stability and the precision of the micro-nano systems, the conditions of which are related with the boundary restraints of the carbon nanotube. To generalize some transverse oscillation problems of the carbon nanotube studied in current references, the elastic restraints at both ends of the single-walled carbon nanotube are considered by means of rotational and translational springs to investigate the effects of the boundary restraints on the chaotic properties of the carbon nanotube in this paper. Based on the generalized multi-symplectic theory, both the generalized multi-symplectic formulations for the governing equation describing the transverse oscillation of the single-walled carbon nanotube subjected to the transverse load and the constraint equations resulting from the elastic restraints are presented firstly. Then, the structure-preserving scheme with discrete constraint equations is constructed to simulate the transverse oscillation process of the carbon nanotube. Finally, the chaotic region of the carbon nanotube is captured, and the oscillations of the two extreme cases (including simply supported and cantilever) are investigated in the numerical investigations. From the numerical results, it can be concluded that the relative bending stiffness coefficient and the absolute bending stiffness coefficients at both ends of the carbon nanotube are two important factors that affect the chaotic region of the carbon nanotube, which provides guidance on the design and manufacture of precise micro-nano mechanical systems. In addition, the different routes to the chaos of the carbon nanotube in two extreme cases are revealed.

  4. Chaotic region of elastically restrained single-walled carbon nanotube.

    PubMed

    Hu, Weipeng; Song, Mingzhe; Deng, Zichen; Zou, Hailin; Wei, Bingqing

    2017-02-01

    The occurrence of chaos in the transverse oscillation of the carbon nanotube in all of the precise micro-nano mechanical systems has a strong impact on the stability and the precision of the micro-nano systems, the conditions of which are related with the boundary restraints of the carbon nanotube. To generalize some transverse oscillation problems of the carbon nanotube studied in current references, the elastic restraints at both ends of the single-walled carbon nanotube are considered by means of rotational and translational springs to investigate the effects of the boundary restraints on the chaotic properties of the carbon nanotube in this paper. Based on the generalized multi-symplectic theory, both the generalized multi-symplectic formulations for the governing equation describing the transverse oscillation of the single-walled carbon nanotube subjected to the transverse load and the constraint equations resulting from the elastic restraints are presented firstly. Then, the structure-preserving scheme with discrete constraint equations is constructed to simulate the transverse oscillation process of the carbon nanotube. Finally, the chaotic region of the carbon nanotube is captured, and the oscillations of the two extreme cases (including simply supported and cantilever) are investigated in the numerical investigations. From the numerical results, it can be concluded that the relative bending stiffness coefficient and the absolute bending stiffness coefficients at both ends of the carbon nanotube are two important factors that affect the chaotic region of the carbon nanotube, which provides guidance on the design and manufacture of precise micro-nano mechanical systems. In addition, the different routes to the chaos of the carbon nanotube in two extreme cases are revealed.

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

    NASA Astrophysics Data System (ADS)

    Omrane, Badr

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

  6. Simple and efficient purification of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Dettlaff-Weglikowska, U.; Roth, S.

    2001-11-01

    Single-walled carbon nanotubes (SWNTs) produced by arc-discharge and laser ablation were purified by selective oxidation in air at 350°C and subsequent HCl treatment at 120°C. Raw soot and purified samples were analyzed with X-ray diffraction, thermogravimetric analysis (TGA), chemical analysis and transmission electron microscopy (TEM). The optimized purification temperature of SWNTs in air, 350°C, has been determined from TGA curves. Repetition of the oxidation and acid treatment, larger than 95 wt.% purity of SWNTs has been obtained.

  7. Phonon Dispersion in Chiral Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Mu, Weihua; Vamivakas, Anthony Nickolas; Fang, Yan; Wang, Bolin

    The method to obtain phonon dispersion of achiral single-wall carbon nanotubes (SWNTs) from 6×6 matrix proposed by Mahan and Jeon7 has been extended to chiral SWNTs. The number of calculated phonon modes of a chiral SWNT (10, 1) is much larger than that of a zigzag one (10, 0) because the number of atoms in the translational unit cell of chiral SWNT is larger than that of an achiral one even though they have relative similar radius. The possible application of our approach to other models with more phonon potential terms beyond Mahan and Jeon's model is discussed.

  8. Phonon density of states of single-wall carbon nanotubes

    PubMed

    Rols; Benes; Anglaret; Sauvajol; Papanek; Fischer; Coddens; Schober; Dianoux

    2000-12-11

    The vibrational density of states of single-wall carbon nanotubes (SWNT) was obtained from inelastic neutron scattering data from 0 to 225 meV. The spectrum is similar to that of graphite above 40 meV, while intratube features are clearly observed at 22 and 36 meV. An unusual energy dependence below 10 meV is assigned to contributions from intertube modes in the 2D triangular lattice of SWNT bundles, and from intertube coupling to intratube excitations. Good agreement between experiment and a calculated density of states for the SWNT lattice is found over the entire energy range.

  9. Superconductivity in 4 angstrom single-walled carbon nanotubes.

    PubMed

    Tang, Z K; Zhang, L; Wang, N; Zhang, X X; Wen, G H; Li, G D; Wang, J N; Chan, C T; Sheng, P

    2001-06-29

    Investigation of the magnetic and transport properties of single-walled small-diameter carbon nanotubes embedded in a zeolite matrix revealed that at temperatures below 20 kelvin, 4 angstrom tubes exhibit superconducting behavior manifest as an anisotropic Meissner effect, with a superconducting gap and fluctuation supercurrent. The measured superconducting characteristics display smooth temperature variations owing to one-dimensional fluctuations, with a mean-field superconducting transition temperature of 15 kelvin. Statistical mechanic calculations based on the Ginzburg-Landau free-energy functional yield predictions that are in excellent agreement with the experiments.

  10. Reaction of folic acid with single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ellison, Mark D.; Chorney, Matthew

    2016-10-01

    The oxygen-containing functional groups on oxidized single-walled carbon nanotubes (SWNTs) are used to covalently bond folic acid molecules to the SWNTs. Infrared spectroscopy confirms intact molecular binding to the SWNTs through the formation of an amide bond between a carboxylic acid group on an SWNT and the primary amine group of folic acid. The folic acid-functionalized SWNTs are readily dispersible in water and phosphate-buffered saline, and the dispersions are stable for a period of two weeks or longer. These folic acid-functionalized SWNTs offer potential for use as biocompatible SWNTs.

  11. Raman scattering test of single-wall carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Hadjiev, V. G.; Iliev, M. N.; Arepalli, S.; Nikolaev, P.; Files, B. S.

    2001-05-01

    Raman spectroscopy is used to infer elastic properties of single-wall carbon nanotubes (SWNTs) in composites. This letter presents strain-induced frequency shift of tangential Raman active modes of SWNTs embedded in epoxy resin subjected to bending. Epoxy curing and sample extension in the tensile strength test are found to create residual strains on the SWNT ropes. We demonstrate that specimen compression in combination with the Raman microprobe technique provides a means for determining of these strains and hence load transfer effectiveness.

  12. Fracture resistance of zigzag single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lu, Qiang; Bhattacharya, Baidurya

    2006-03-01

    Carbon nanotubes (CNTs) are known to possess extraordinary strength, stiffness and ductility properties. Their fracture resistance is an important issue from the perspective of durability and reliability of CNT-based materials and devices. According to existing studies, brittle fracture is one of the important failure modes of single-walled carbon nanotube (SWNT) failure due to mechanical loading. However, based on the authors' knowledge, the fracture resistance of CNTs has not been quantified so far. In this paper, the fracture resistance of zigzag SWNTs with preexisting defects is calculated using fracture mechanics concepts based on atomistic simulations. The interatomic forces are modelled with a modified Morse potential; the Anderson thermostat is used for temperature control. The problem of unstable crack growth at finite temperature, presumably caused by the lattice trapping effect, is circumvented by computing the strain energy release rate through a series of displacement-controlled tensile loading of SWNTs (applied through moving the outermost layer of atoms at one end at constant strain rate of 9.4 × 10-4 ps-1) with pre-existing crack-like defects of various lengths. The strain energy release rate, G, is computed for (17, 0), (28, 0) and (35, 0) SWNTs (each with aspect ratio 4) with pre-existing cracks up to 29.5 Å long. The fracture resistance, Gc, is determined as a function of crack length for each tube at three different temperatures (1, 300 and 500 K). A significant dependence of Gc on crack length is observed, reminiscent of the rising R curve behaviour of metals at the macroscale: for the zigzag nanotubes Gc increases with crack length at small length, and tends to reach a constant value if the tube diameter is large enough. We suspect that the lattice trapping effect plays the role of crack tip plasticity at the atomic scale. For example, at 300 K, Gc for the (35, 0) tube with aspect ratio 4 converges to 6 J m-2 as the crack length exceeds 20

  13. Characterization of single-walled carbon nanotubes for environmental implications

    USGS Publications Warehouse

    Agnihotri, S.; Rostam-Abadi, M.; Rood, M.J.

    2004-01-01

    Adsorption capacities of N2 and various organic vapors (methyl-ethyl ketone (MEK), toluene, and cyclohexane) on select electric-arc and HiPco produced single walled carbon nanotubes (SWNT) were measured at 77 and 298 K, respectively. The amount of N2 adsorbed on a SWNT sample depended on the sample purity, methodology, and on the sample age. Adsorption capacities of organic vapors (100-1000 ppm vol) on SWNT in humid conditions were much higher than those for microporous activated carbons. These results established a foundation for additional studies related to potential environmental applications of SWNT. The MEK adsorption capacities of samples EA95 and CVD80 and mesoporous tire-derived activated carbon in humid conditions were lower than in dry conditions. This is an abstract of a paper presented at the AIChE Annual Meeting (Austin, TX 11/7-12/2004).

  14. Electroluminescence from single-wall carbon nanotube network transistors.

    PubMed

    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.

  15. Size engineering of metal nanoparticles to diameter-specified growth of single-walled carbon nanotubes with horizontal alignment on quartz

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Ju; Lee, Byeong-Joo; Lee, Seung-Hwan; Jeong, Goo-Hwan

    2012-03-01

    The electronic, physical and optical properties of single-walled carbon nanotubes (SWNTs) are governed by their diameter and chirality, and thus much research has been focused on controlling the diameter and chirality of SWNTs. To date, control of the catalyst particle size has been thought to be one of the most promising approaches to control the diameter or chirality of SWNTs owing to the correlation between catalyst particle size and tube diameter. In this study, we demonstrate the size engineering of catalytic nanoparticles for the controlled growth of diameter-specified and horizontally aligned SWNTs on quartz substrates. Uniformly sized iron nanoparticles derived from ferritin molecules were used as a catalyst, and their size was intentionally decreased via thermal heat treatment at 900 °C under atmospheric Ar ambient. ST-cut quartz wafers were used as growth substrates in order to elucidate the effect of the size of the nanoparticles on the tube diameter and the effect of catalyst size on the degree of parallel alignment on the quartz substrates. SWNTs grown by chemical vapor deposition using methane as feedstock exhibited a high degree of horizontal alignment when the particle density was low enough to produce individual SWNTs without bundling. Annealing for 60 min at 900 °C produced a reduction of nanoparticle diameter from 2.6 to 1.8 nm and a decrease in the mean tube diameter from 1.2 to 0.8 nm, respectively. Raman spectroscopy results corroborated the observation that prolonged heat treatment of nanoparticles yields thinner tubes with narrower size distributions. The results of this work suggest that straightforward thermal annealing can be a facile way to obtain uniform-sized SWNTs as well as catalytic nanoparticles.

  16. Single Wall Carbon Nano Tube Films and Coatings

    NASA Astrophysics Data System (ADS)

    Sreekumar, T. V.; Kumar, Satish; Ericson, Lars M.; Smalley, Richard E.

    2002-03-01

    Purified single wall carbon nano tubes (SWNTs) produced from the high-pressure carbon monoxide (HiPCO) process have been dissolved /dispersed in oleum. These solutions /dispersions were optically homogeneous and have been used to form stand-alone SWNT films. The washed, dried, and heat-treated films are isotropic. The scanning electron micrographs of the film surface shows that the nanotube ropes (or fibrils) of about 20 nm diameters are arranged just like macroscopic fibers in a non-woven fabric. Polarized Raman spectroscopy of the SWNT film confirms the isotropic nature of these films. The films are being characterized for their thermal, mechanical as well electrical properties. Thin nano tube coatings, including optically transparent coatings, have also been made on a variety of substrates such as glass, polyethylene, polystyrene, polypropylene, silicon wafer, as well as stainless steel.

  17. Surface oxidation study of single wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lebrón-Colón, M.; Meador, M. A.; Lukco, D.; Solá, F.; Santos-Pérez, J.; McCorkle, L. S.

    2011-11-01

    Functionalization of single wall carbon nanotubes (SWCNTs) is desirable to enhance their ability to be incorporated into polymers and enhance their bonding with the matrix. One approach to carbon nanotube functionalization is by oxidation via a strong oxidizing agent or refluxing in strong acids. However, this approach can damage the nanotubes, leading to the introduction of defects and/or shorter nanotubes. Such damage can adversely affect the mechanical, thermal, and electrical properties. A more benign approach to nanotube functionalization has been developed involving photo-oxidation. Chemical analysis by XPS revealed that the oxygen content of the photo-oxidized SWCNTs was 11.3 at.% compared to 6.7 at.% for SWCNTs oxidized by acid treatment. The photo-oxidized SWCNTs produced by this method can be used directly in various polymer matrices or can be further modified by additional chemical reactions.

  18. Storage of Hydrogen in Single-Walled Carbon Nanotubes

    SciTech Connect

    Dillon, A. C.; Jones, K. M.; Bekkedahl, T. A.; Kiang, C. H.; Bethune, D. S.; Heben, M. J.

    1997-03-27

    Pores of molecular dimensions can adsorb large quantities of gases owing to the enhanced density of the adsorbed material inside the pores, a consequence of the attractive potential of the pore walls. Pederson and Broughton have suggested that carbon nanotubes, which have diameters of typically a few nanometres, should be able to draw up liquids by capillarity, and this effect has been seen for low-surface-tension liquids in large-diameter, multi-walled nanotubes. Here we show that a gas can condense to high density inside narrow, single-walled nanotubes (SWNTs). Temperature-programmed desorption spectroscopy shows that hydrogen will condense inside SWNTs under conditions that do not induce adsorption within a standard mesoporous activated carbon. The very high hydrogen uptake in these materials suggests that they might be effective as a hydrogen-storage material for fuel-cell electric vehicles.

  19. Processing of single walled carbon nanotubes for nanocomposites

    NASA Astrophysics Data System (ADS)

    Knapp, Angela M.

    An existing electric arc discharge (EAD) apparatus was found to produce only small quantities of single-walled carbon nanotubes (SWNT), therefore an in depth evaluation of the various parameters was performed in order to optimize the SWNT yield. A systematic study on the current applied (48-116 A) and morphology of the arc during EAD experiments was performed, a study of this type has not been previously reported in literature. Our findings include that the current being applied to the electrodes, as controlled by a commercial software program, was ˜ 20 A lower than expected. Currents in the range of 70-90 A appear to be optimal for this EAD system as the yield of SWNT is consistent with commercially produced SWNT also fabricated with an EAD system. During the experiments, the current was not constant, but fluctuated over a range of values, 7-20 A ranges were not uncommon. Concurrently, the gap between the electrodes was also non-constant, a gap of less than 1 mm or contact as the anode "stabs" the cathode was witnessed. Subsequent analysis of the yield of SVVNT, as a function of the current as well as the physical location in the EAD chamber where the yield was greatest, was performed with simultaneous thermogravimetric analysis and differential thermal analysis. Significant differences in the concentration of metal catalysts used to fabricate the SWNT were observed between sample areas in the chamber. Moreover, an anomalous peak was observed in the differential thermal analysis trace between the 350-400°C. Subsequent analysis of relevant constituent materials was investigated to identify the cause of this anomaly. Static and dynamic mechanical analysis was performed on highly drawn fibers of neat polystyrene and its composites containing 0.3 wt.% of a commercial SWNT containing soot. Though the dynamic and static measurements of fibers in the 130-150 mum did not show improvement with the addition of the filler, composite fibers of 20-50 mum were statistically

  20. Single-Walled Carbon Nanohorns for Energy Applications

    PubMed Central

    Zhang, Zhichao; Han, Shuang; Wang, Chao; Li, Jianping; Xu, Guobao

    2015-01-01

    With the growth of the global economy and population, the demand for energy is increasing sharply. The development of environmentally a benign and reliable energy supply is very important and urgent. Single-walled carbon nanohorns (SWCNHs), which have a horn-shaped tip at the top of single-walled nanotube, have emerged as exceptionally promising nanomaterials due to their unique physical and chemical properties since 1999. The high purity and thermal stability, combined with microporosity and mesoporosity, high surface area, internal pore accessibility, and multiform functionalization make SWCNHs promising candidates in many applications, such as environment restoration, gas storage, catalyst support or catalyst, electrochemical biosensors, drug carrier systems, magnetic resonance analysis and so on. The aim of this review is to provide a comprehensive overview of SWCNHs in energy applications, including energy conversion and storage. The commonly adopted method to access SWCNHs, their structural modifications, and their basic properties are included, and the emphasis is on their application in different devices such as fuel cells, dye-sensitized solar cells, supercapacitors, Li-ion batteries, Li-S batteries, hydrogen storage, biofuel cells and so forth. Finally, a perspective on SWCNHs’ application in energy is presented. PMID:28347092

  1. Molecular Imaging with Single-Walled Carbon Nanotubes

    PubMed Central

    Hong, Hao; Gao, Ting; Cai, Weibo

    2011-01-01

    Nanoparticle-based molecular imaging has emerged as an interdisciplinary field which involves physics, chemistry, engineering, biology, and medicine. Single-walled carbon nanotubes (SWCNTs) have unique properties which make them suitable for applications in a variety of imaging modalities, such as magnetic resonance, near-infrared fluorescence, Raman spectroscopy, photoacoustic tomography, and radionuclide-based imaging. In this review, we will summarize the current state-of-the-art of SWCNTs in molecular imaging applications. Multifunctionality is the key advantage of nanoparticles over traditional approaches. Targeting ligands, imaging labels, therapeutic drugs, and many other agents can all be integrated into the nanoparticle to allow for targeted molecular imaging and molecular therapy by encompassing many biological and biophysical barriers. A multifunctional, SWCNT-based nanoplatform holds great potential for clinical applications in the future. PMID:21754949

  2. Single Wall Carbon Nanotube-polymer Solar Cells

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila G.; Castro, Stephanie L.; Landi, Brian J.; Gennett, Thomas; Raffaelle, Ryne P.

    2005-01-01

    Investigation of single wall carbon nanotube (SWNT)-polymer solar cells has been conducted towards developing alternative lightweight, flexible devices for space power applications. Photovoltaic devices were constructed with regioregular poly(3-octylthiophene)-(P3OT) and purified, >95% w/w, laser-generated SWNTs. The P3OT composites were deposited on ITO-coated polyethylene terapthalate (PET) and I-V characterization was performed under simulated AM0 illumination. Fabricated devices for the 1.0% w/w SWNT-P3OT composites showed a photoresponse with an open-circuit voltage (V(sub oc)) of 0.98 V and a short-circuit current density (I(sub sc)) of 0.12 mA/sq cm. Optimization of carrier transport within these novel photovoltaic systems is proposed, specifically development of nanostructure-SWNT complexes to enhance exciton dissociation.

  3. Single-walled carbon nanotubes for high-performance electronics.

    PubMed

    Cao, Qing; Han, Shu-jen

    2013-10-07

    Single-walled carbon nanotubes (SWNT) could replace silicon in high-performance electronics with their exceptional electrical properties and intrinsic ultra-thin body. During the past five years, the major focus of this field is gradually shifting from proof-of-concept prototyping in academia to technology development in industry with emphasis on manufacturability and integration issues. This article reviews recent advances, starting with experimental and modeling works that evaluate the potential of adopting SWNTs in ultimately scaled transistors. Techniques to separate nanotubes according to their electronic types and assemble them into aligned arrays are then discussed, followed by a description of the engineering aspects in their implementation in integrated circuits and systems. A concluding discussion provides some perspectives on future challenges and research opportunities.

  4. Generalizing thermodynamic properties of bulk single-walled carbon nanotubes

    SciTech Connect

    Rodriguez, Kenneth R. Nanney, Warren A.; Maddux, Cassandra J.A.; Martínez, Hernán L.; Malone, Marvin A.; Coe, James V.

    2014-12-15

    The enthalpy and Gibbs free energy thermodynamical potentials of single walled carbon nanotubes were studied of all types (armchairs, zig-zags, chirals (n>m), and chiral (n

  5. Volumetric hydrogen storage in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, C.; Yang, Q. H.; Tong, Y.; Cong, H. T.; Cheng, H. M.

    2002-04-01

    Macroscopically long ropes of aligned single-walled carbon nanotubes (SWNTs), synthesized by a hydrogen and argon arc discharge method, were cold pressed into tablets without any binder for measurements of their volumetric hydrogen storage capacity. The typical apparent density of the tablets was measured to be around 1.7 g/cm3 with respect to a molding pressure of 0.75 Gpa. A volumetric and mass hydrogen storage capacity of 68 kg H2/m3 and 4.0 wt %, respectively, was achieved at room temperature under a pressure of 11 MPa for suitably pretreated SWNT tablets, and more than 70% of the hydrogen adsorbed can be released under ambient pressure at room temperature. Pore structure analysis indicated that the molding process diminished the mesopore volume of the SWNT ropes, but exerts little influence on their intrinsic pore textures.

  6. Investigation of Hydrogen Adsorption on Single Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Nam, Sang-Hun; Jeong, Seong Hun; Lee, Soon-Bo; Boo, Jin-Hyo

    We have investigated adsorption and desorption condition of atomic hydrogen on single-walled nanotubes (SWCNTs) using ultraviolet photoelectron spectroscopy (UPS) and thermal desorption spectroscopy (TDS). The SWCNTs were made by the high pressure carbon monoxide (HiPCO) method. In our results, we observe from UPS data absorptive states reduce with increasing hydrogen doses and a new peak is developed near 8.6 eV and other points. But this peak is gradually diminished with pumping time. The TDS data show two characteristic peaks at 640 and 790K. By comparing with density functional calculations, we propose these peaks to be related to the presence of atomic hydrogen. Therefore, we can know that there are two adsorption sites on SWCNTs. Also we observed physisorption and chemisorption site by pumping time. We note that the UPS data are fully recoverable after hydrogen desorption at 1200K.

  7. Radiation Protection Using Single-Wall Carbon Nanotube Derivatives

    NASA Technical Reports Server (NTRS)

    Tour, James M.; Lu, Meng; Lucente-Schultz, Rebecca; Leonard, Ashley; Doyle, Condell Dewayne; Kosynkin, Dimitry V.; Price, Brandi Katherine

    2011-01-01

    This invention is a means of radiation protection, or cellular oxidative stress mitigation, via a sequence of quenching radical species using nano-engineered scaffolds, specifically single-wall carbon nanotubes (SWNTs) and their derivatives. The material can be used as a means of radiation protection by reducing the number of free radicals within, or nearby, organelles, cells, tissue, organs, or living organisms, thereby reducing the risk of damage to DNA and other cellular components (i.e., RNA, mitochondria, membranes, etc.) that can lead to chronic and/or acute pathologies, including but not limited to cancer, cardiovascular disease, immuno-suppression, and disorders of the central nervous system. In addition, this innovation could be used as a prophylactic or antidote for accidental radiation exposure, during high-altitude or space travel where exposure to radiation is anticipated, or to protect from exposure from deliberate terrorist or wartime use of radiation- containing weapons.

  8. Dispersionless propagation of electron wavepackets in single-walled carbon nanotubes

    SciTech Connect

    Rosati, Roberto; Rossi, Fausto; Dolcini, Fabrizio

    2015-06-15

    We investigate the propagation of electron wavepackets in single-walled carbon nanotubes via a Lindblad-based density-matrix approach that enables us to account for both dissipation and decoherence effects induced by various phonon modes. We show that, while in semiconducting nanotubes the wavepacket experiences the typical dispersion of conventional materials, in metallic nanotubes its shape remains essentially unaltered, even in the presence of the electron-phonon coupling, up to micron distances at room temperature.

  9. Growth and characterization of high-density mats of single-walled carbon nanotubes for interconnects

    SciTech Connect

    Robertson, J.; Zhong, G.; Telg, H.; Thomsen, C.; Warner, J. H.; Briggs, G. A. D.; Dettlaff-Weglikowska, U.; Roth, S.

    2008-10-20

    We grow high-density, aligned single wall carbon nanotube mats for use as interconnects in integrated circuits by remote plasma chemical vapor deposition from a Fe-Al{sub 2}O{sub 3} thin film catalyst. We carry out extensive Raman characterization of the resulting mats, and find that this catalyst system gives rise to a broad range of nanotube diameters, with no preferential selectivity of semiconducting tubes, but with at least 1/3 of metallic tubes.

  10. AC Power Consumption of Single-Walled Carbon Nanotube Interconnects: Non-Equilibrium Green's Function Simulation

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takahiro; Sasaoka, Kenji; Watanabe, Satoshi

    2012-04-01

    We theoretically investigate the emittance and dynamic dissipation of a nanoscale interconnect consisting of a metallic single-walled carbon nanotube using the non-equilibrium Green's function technique for AC electronic transport. We show that the emittance and dynamic dissipation depend strongly on the contact conditions of the interconnect and that the power consumption can be reduced by adjusting the contact conditions. We propose an appropriate condition of contact that yields a high power factor and low apparent power.

  11. Extracellular entrapment and degradation of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Farrera, Consol; Bhattacharya, Kunal; Lazzaretto, Beatrice; Andón, Fernando T.; Hultenby, Kjell; Kotchey, Gregg P.; Star, Alexander; Fadeel, Bengt

    2014-05-01

    Neutrophils extrude neutrophil extracellular traps (NETs) consisting of a network of chromatin decorated with antimicrobial proteins to enable non-phagocytic killing of microorganisms. Here, utilizing a model of ex vivo activated human neutrophils, we present evidence of entrapment and degradation of carboxylated single-walled carbon nanotubes (SWCNTs) in NETs. The degradation of SWCNTs was catalyzed by myeloperoxidase (MPO) present in purified NETs and the reaction was facilitated by the addition of H2O2 and NaBr. These results show that SWCNTs can undergo acellular, MPO-mediated biodegradation and imply that the immune system may deploy similar strategies to rid the body of offending microorganisms and engineered nanomaterials.Neutrophils extrude neutrophil extracellular traps (NETs) consisting of a network of chromatin decorated with antimicrobial proteins to enable non-phagocytic killing of microorganisms. Here, utilizing a model of ex vivo activated human neutrophils, we present evidence of entrapment and degradation of carboxylated single-walled carbon nanotubes (SWCNTs) in NETs. The degradation of SWCNTs was catalyzed by myeloperoxidase (MPO) present in purified NETs and the reaction was facilitated by the addition of H2O2 and NaBr. These results show that SWCNTs can undergo acellular, MPO-mediated biodegradation and imply that the immune system may deploy similar strategies to rid the body of offending microorganisms and engineered nanomaterials. Electronic supplementary information (ESI) available: Suppl. Fig. 1 - length distribution of SWCNTs; suppl. Fig. 2 - characterization of pristine vs. oxidized SWCNTs; suppl. Fig. 3 - endotoxin evaluation; suppl. Fig. 4 - NET characterization; suppl. Fig. 5 - UV-Vis/NIR analysis of biodegradation of oxidized SWCNTs; suppl. Fig. 6 - cytotoxicity of partially degraded SWCNTs. See DOI: 10.1039/c3nr06047k

  12. Single-Wall Carbon Nanotube Anodes for Lithium Cells

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Raffaelle, Ryne; Gennett, Tom; Kumta, Prashant; Maranchi, Jeff; Heben, Mike

    2006-01-01

    In recent experiments, highly purified batches of single-wall carbon nanotubes (SWCNTs) have shown promise as superior alternatives to the graphitic carbon-black anode materials heretofore used in rechargeable thin-film lithium power cells. The basic idea underlying the experiments is that relative to a given mass of graphitic carbon-black anode material, an equal mass of SWCNTs can be expected to have greater lithium-storage and charge/discharge capacities. The reason for this expectation is that whereas the microstructure and nanostructure of a graphitic carbon black is such as to make most of the interior of the material inaccessible for intercalation of lithium, a batch of SWCNTs can be made to have a much more open microstructure and nanostructure, such that most of the interior of the material is accessible for intercalation of lithium. Moreover, the greater accessibility of SWCNT structures can be expected to translate to greater mobilities for ion-exchange processes and, hence, an ability to sustain greater charge and discharge current densities.

  13. Interactions between single-walled carbon nanotubes and lysozyme.

    PubMed

    Bomboi, F; Bonincontro, A; La Mesa, C; Tardani, F

    2011-03-15

    Dispersions of single-walled and non-associated carbon nanotubes in aqueous lysozyme solution were investigated by analyzing the stabilizing effect of both protein concentration and pH. It was inferred that the medium pH, which significantly modifies the protein net charge and (presumably) conformation, modulates the mutual interactions with carbon nanotubes. At fixed pH, in addition, the formation of protein/nanotube complexes scales with increasing lysozyme concentration. Electrophoretic mobility, dielectric relaxation and circular dichroism were used to determine the above features. According to circular dichroism, lysozyme adsorbed onto nanotubes could essentially retain its native conformation, but the significant amount of free protein does not allow drawing definitive conclusions on this regard. The state of charge and charge distribution around nanotubes was inferred by combining electrophoretic mobility and dielectric relaxation methods. The former gives information on changes in the surface charge density of the complexes, the latter on modifications in the electrical double layer thickness around them. Such results are complementary each other and univocally indicate that some LYS molecules take part to binding. Above a critical protein/nanotube mass ratio, depletion phenomena were observed. They counteract the stabilization mechanism, with subsequent nanotube/nanotube aggregation and phase separation. Protein-based depletion phenomena are similar to formerly reported effects, observed in aqueous surfactant systems containing carbon nanotubes.

  14. Improved cellular uptake of functionalized single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Antonelli, A.; Serafini, S.; Menotta, M.; Sfara, C.; Pierigé, F.; Giorgi, L.; Ambrosi, G.; Rossi, L.; Magnani, M.

    2010-10-01

    Single-walled carbon nanotubes (SWNTs) due to their unique structural and physicochemical properties, have been proposed as delivery systems for a variety of diagnostic and therapeutic agents. However, SWNTs have proven difficult to solubilize in aqueous solution, limiting their use in biological applications. In an attempt to improve SWNTs' solubility, biocompatibility, and to increase cell penetration we have thoroughly investigated the construction of carbon scaffolds coated with aliphatic carbon chains and phospholipids to obtain micelle-like structures. At first, oxidized SWNTs (2370 ± 30 nmol mg - 1 of SWNTs) were covalently coupled with an alcoholic chain (stearyl alcohol, C18H37OH; 816 nmol mg - 1 of SWNTs). Subsequently, SWNTs-COOC18H37 derivatives were coated with phosphatidylethanolamine (PE) or -serine (PS) phospholipids obtaining micelle-like structures. We found that cellular uptake of these constructs by phagocytic cells occurs via an endocytotic mechanism for constructs larger than 400 nm while occurs via diffusion through the cell membrane for constructs up to 400 nm. The material that enters the cell by phagocytosis is actively internalized by macrophages and localizes inside endocytotic vesicles. In contrast the material that enters the cells by diffusion is found in the cell cytosol. In conclusion, we have realized new biomimetic constructs based on alkylated SWNTs coated with phospholipids that are efficiently internalized by different cell types only if their size is lower than 400 nm. These constructs are not toxic to the cells and could now be explored as delivery systems for non-permeant cargoes.

  15. Investigation of Hydrogen Storage in Single Walled Carbon Nanotubes for Fuel Cells-2

    DTIC Science & Technology

    2010-03-11

    1 Final Report Title: Investigation of hydrogen storage in Single Walled Carbon Nanotubes for fuel cells - 2 AFOSR/AOARD...SUBTITLE Investigation of hydrogen storage in single walled carbon nanotubes for fuel cells-2 5a. CONTRACT NUMBER FA23860914157 5b. GRANT NUMBER...SUPPLEMENTARY NOTES 14. ABSTRACT Single walled carbon nanotubes (SWCNTs) dispersed in 2-propanol are deposited on the alumina substrate using drop caste

  16. Phototransformation-Induced Aggregation of Functionalized Single-Walled Carbon Nanotubes: The Importance of Amorphous Carbon

    EPA Science Inventory

    Single-walled carbon nanotubes (SWCNTs) with proper functionalization are desirable for applications that require dispersion in aqueous and biological environments, and functionalized SWCNTs also serve as building blocks for conjugation with specific molecules in these applicatio...

  17. Economic assessment of single-walled carbon nanotube processes

    NASA Astrophysics Data System (ADS)

    Isaacs, J. A.; Tanwani, A.; Healy, M. L.; Dahlben, L. J.

    2010-02-01

    The carbon nanotube market is steadily growing and projected to reach 1.9 billion by 2010. This study examines the economics of manufacturing single-walled carbon nanotubes (SWNT) using process-based cost models developed for arc, CVD, and HiPco processes. Using assumed input parameters, manufacturing costs are calculated for 1 g SWNT for arc, CVD, and HiPco, totaling 1,906, 1,706, and 485, respectively. For each SWNT process, the synthesis and filtration steps showed the highest costs, with direct labor as a primary cost driver. Reductions in production costs are calculated for increased working hours per day and for increased synthesis reaction yield (SRY) in each process. The process-based cost models offer a means for exploring opportunities for cost reductions, and provide a structured system for comparisons among alternative SWNT manufacturing processes. Further, the models can be used to comprehensively evaluate additional scenarios on the economics of environmental, health, and safety best manufacturing practices.

  18. Fluorescent single walled carbon nanotube/silica composite materials.

    PubMed

    Satishkumar, B C; Doorn, Stephen K; Baker, Gary A; Dattelbaum, Andrew M

    2008-11-25

    We present a new approach for the preparation of single walled carbon nanotube silica composite materials that retain the intrinsic fluorescence characteristics of the encapsulated nanotubes. Incorporation of isolated nanotubes into optically transparent matrices, such as sol-gel prepared silica, to take advantage of their near-infrared emission properties for applications like sensing has been a challenging task. In general, the alcohol solvents and acidic conditions required for typical sol-gel preparations disrupt the nanotube/surfactant assembly and cause the isolated nanotubes to aggregate leading to degradation of their fluorescence properties. To overcome these issues, we have used a sugar alcohol modified silica precursor molecule, diglycerylsilane, for encapsulation of nanotubes in silica under aqueous conditions and at neutral pH. The silica/nanotube composite materials have been prepared as monoliths, at least 5 mm thick, or as films (<1 mm) and were characterized using fluorescence and Raman spectroscopy. In the present work we have investigated the fluorescence characteristics of the silica encapsulated carbon nanotubes by means of redox doping studies as well as demonstrated their potential for biosensing applications. Such nanotube/silica composite systems may allow for new sensing and imaging applications that are not currently achievable.

  19. Optical properties of armchair (7, 7) single walled carbon nanotubes

    SciTech Connect

    Gharbavi, K.; Badehian, H.

    2015-07-15

    Full potential linearized augmented plane waves method with the generalized gradient approximation for the exchange-correlation potential was applied to calculate the optical properties of (7, 7) single walled carbon nanotubes. The both x and z directions of the incident photons were applied to estimate optical gaps, dielectric function, electron energy loss spectroscopies, optical conductivity, optical extinction, optical refractive index and optical absorption coefficient. The results predict that dielectric function, ε (ω), is anisotropic since it has higher peaks along z-direction than x-direction. The static optical refractive constant were calculated about 1.4 (z-direction) and 1.1 (x- direction). Moreover, the electron energy loss spectroscopy showed a sharp π electron plasmon peaks at about 6 eV and 5 eV for z and x-directions respectively. The calculated reflection spectra show that directions perpendicular to the tube axis have further optical reflection. Moreover, z-direction indicates higher peaks at absorption spectra in low range energies. Totally, increasing the diameter of armchair carbon nanotubes cause the optical band gap, static optical refractive constant and optical reflectivity to decrease. On the other hand, increasing the diameter cause the optical absorption and the optical conductivity to increase. Moreover, the sharp peaks being illustrated at optical spectrum are related to the 1D structure of CNTs which confirm the accuracy of the calculations.

  20. Optical properties of single-walled carbon nanotube aerogels

    NASA Astrophysics Data System (ADS)

    Ostojic, Gordana

    2012-02-01

    A network of connected single-walled carbon nanotubes (SWNT) is created by a novel DNA-protein complex directed assembly. Due to a point-like nature of connectors, the SWNT aerogel represents a network of self-suspended nanotubes with a record ultra-low density of less 0.75 mg/cm^3. The assembly method and low density enables a direct comparison of optical properties of nanotubes in solvent and air to surfactant solubilized nanotubes. Optical properties of SWNT gels are investigated using optical absorption, photoluminescence and Raman spectroscopy. Gelled nanotubes in water and in the low population regime behave similar to solubilized nanotubes. In contrast, photoluminescence of SWNT aerogels exhibit nonlinear effects and a phonon-induced broadening. In addition, aerogels show a previously unobserved photoluminescence peak at 1.3 eV that corresponds to a phonon-assisted recombination of photoexcited charges. Raman spectra of carbon nanotube aerogels display narrow peaks due to the phonon decoupling of suspended SWNTs in air and a redistribution of G phonon population due to nonlinear effects.

  1. MINIMAL INFLAMMOGENICITY OF PRISTINE SINGLE-WALL CARBON NANOTUBES

    PubMed Central

    TOYOKUNI, SHINYA; JIANG, LI; KITAURA, RYO; SHINOHARA, HISANORI

    2015-01-01

    ABSTRACT Carbon nanotubes (CNTs) are a novel synthetic material comprising only carbon atoms. Based on its rigidity, its electrical and heat conductivity and its applicability to surface manufacturing, this material is expected to have numerous applications in industry. However, due to the material’s dimensional similarity to asbestos fibers, its carcinogenicity was hypothesized during the last decade, and indeed, we have shown that multi-wall CNTs (MWCNTs) of 50 nm in diameter are potently carcinogenic to mesothelial cells after intraperitoneal injection. Additionally, we suggested that inflammogenicity after intraperitoneal injection can predict mesothelial carcinogenesis. However, few data have been published on the intraperitoneal inflammogenicity of single-wall CNTs (SWCNTs). Here, we conducted a series of studies on SWCNTs using both intraperitoneal injection into rats and MeT5A mesothelial cells. Intraperitoneal injection of 10 mg SWCNTs caused no remarkable inflammation in the abdominal cavity, and the exposure of MeT5A cells to up to 25 μg/cm2 SWCNTs did not alter proliferation. MWCNTs of 50 nm in diameter were used as a positive control, and tangled MWCNTs of 15 nm in diameter were used as a negative control. The results suggest that SWCNTs are a low-risk material with respect to mesothelial carcinogenesis. PMID:25797984

  2. Suspended single-walled carbon nanotube fluidic sensors

    NASA Astrophysics Data System (ADS)

    Son, B. H.; Park, Ji-Yong; Lee, Soonil; Ahn, Y. H.

    2015-09-01

    In this paper, we demonstrate the fabrication of liquid flow sensors employing partially suspended single-walled carbon nanotubes (SWNTs). We have found that the sign of the conductance change in SWNT flow sensors is not influenced by the direction of water flow for both supported and suspended devices. Therefore, the streaming potential is not the principal mechanism of the SWNT sensor response. Instead, the conductance change is more likely due to a reduction in the cation density in the electrical double layer, whose equilibrium conditions are determined by the liquid flow rate. More importantly, we have found that the sensitivity of suspended SWNT devices is more than 10 times greater than that of supported SWNT devices. A reduced screening effect and an increase in effective sensing volume are responsible for the enhanced sensitivity, which is consistent with the ion depletion model. We also have measured conductance as a function of gate bias at different flow rates and have determined the flow-rate dependent effective charge density, which influences the electrostatic configuration around SWNT devices.In this paper, we demonstrate the fabrication of liquid flow sensors employing partially suspended single-walled carbon nanotubes (SWNTs). We have found that the sign of the conductance change in SWNT flow sensors is not influenced by the direction of water flow for both supported and suspended devices. Therefore, the streaming potential is not the principal mechanism of the SWNT sensor response. Instead, the conductance change is more likely due to a reduction in the cation density in the electrical double layer, whose equilibrium conditions are determined by the liquid flow rate. More importantly, we have found that the sensitivity of suspended SWNT devices is more than 10 times greater than that of supported SWNT devices. A reduced screening effect and an increase in effective sensing volume are responsible for the enhanced sensitivity, which is consistent

  3. Tuning Thermoelectric Properties of Chirality Selected Single Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Yanagi, Kazuhiro; Oshima, Yuki; Kitamura, Yoshimasa; Maniwa, Yutaka

    Thermoelectrics are a very important technology for efficiently converting waste heat into electric power. Hicks and Dresselhaus proposed an important approach to innovate the performance of thermoelectric devices, which involves using one-dimensional materials and properly tuning their Fermi level (PRB 1993). Therefore, understanding the relationship between the thermoelectric performance and the Fermi level of one-dimensional materials is of great importance to maximize their thermoelectric performance. Single wall carbon nanotube (SWCNT) is an ideal model for one-dimensional materials. Previously we reported continuous p-type and n-type control over the Seebeck coefficients of semiconducting SWCNT networks with diameter of 1.4 nm through an electric double layer transistor setup using an ionic liquid as the electrolyte (Yanagi et al., Nano Lett. 14, 6437 2014). We clarified the thermoelectric properties of semiconducting SWCNTs with diameter of 1.4 nm as a function of Fermi level. In this study, we investigated how the chiralities or electronic structures of SWCNTs influence on the thermoelectric properties. We found the significant difference in the line-shape of Seebeck coefficient as a function of gate voltage between the different electronic structures of SWCNTs.

  4. Interaction between alkyl radicals and single wall carbon nanotubes.

    PubMed

    Denis, Pablo A

    2012-06-30

    The addition of primary, secondary, and tertiary alkyl radicals to single wall carbon nanotubes (SWCNTs) was studied by means of dispersion corrected density functional theory. The PBE, B97-D, M06-L, and M06-2X functionals were used. Consideration of Van der Waals interactions is essential to obtain accurate addition energies. In effect, the enthalpy changes at 298 K, for the addition of methyl, ethyl, isopropyl, and tert-butyl radicals onto a (5,5) SWCNT are: -25.7, -25.1, -22.4, and -16.6 kcal/mol, at the M06-2X level, respectively, whereas at PBE/6-31G* level they are significantly lower: -25.0, -19.0, -16.7, and -5.0 kcal/mol respectively. Although the binding energies are small, the attached alkyl radicals are expected to be stable because of the large desorption barriers. The importance of nonbonded interactions was more noticeable as we moved from primary to tertiary alkyl radicals. Indeed, for the tert-butyl radical, physisorption onto the (11,0) SWCNT is preferred rather than chemisorption. The bond dissociation energies determined for alkyl radicals and SWCNT follow the trend suggested by the consideration of radical stabilization energies. However, they are in disagreement with some degrees of functionalization observed in recent experiments. This discrepancy would stem from the fact that for some HiPco nanotubes, nonbonded interactions with alkyl radicals are stronger than covalent bonds.

  5. Complexation of aromatic drugs with single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Buchelnikov, Anatoly S.; Voronin, Dmitry P.; Kostjukov, Viktor V.; Deryabina, Tatyana A.; Khrapatiy, Sergii V.; Prylutskyy, Yuriy I.; Ritter, Uwe; Evstigneev, Maxim P.

    2014-07-01

    We report a detailed study of the complexation of aromatic molecules and drugs with the surface of single-walled carbon nanotubes (SWCNTs, the diameter and the length ranges are 0.5-2 nm and 1-5 μm, respectively) in terms of equilibrium binding constants, K. It is found that the binding constants have magnitudes of the order of 104-105 M-1 and that there is some ligand specificity to the SWCNT surface depending on the structure of the aromatic molecule. The observed specificity is strongly governed by the curvature of the ligand chromophore and the type of side chains, resulting in the highest K for methylene blue which closely matches the curvature of the SWCNT surface. Stabilization of the drug-SWCNT complexes is found to be mainly due to intermolecular van der Waals forces and to a lesser extent by hydrophobic interactions. The approach suggested for determination of the binding parameters may be used as an alternative, or complementary, to standard Langmuir analysis.

  6. Coarse-grained potentials of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Junhua; Jiang, Jin-Wu; Wang, Lifeng; Guo, Wanlin; Rabczuk, Timon

    2014-11-01

    We develop the coarse-grained (CG) potentials of single-walled carbon nanotubes (SWCNTs) in CNT bundles and buckypaper for the study of the static and dynamic behaviors. The explicit expressions of the CG stretching, bending and torsion potentials for the nanotubes are obtained by the stick-spiral and the beam models, respectively. The non-bonded CG potentials between two different CG beads are derived from analytical results based on the cohesive energy between two parallel and crossing SWCNTs from the van der Waals interactions. We show that the CG model is applicable to large deformations of complex CNT systems by combining the bonded potentials with non-bonded potentials. Checking against full atom molecular dynamics calculations and our analytical results shows that the present CG potentials have high accuracy. The established CG potentials are used to study the mechanical properties of the CNT bundles and buckypaper efficiently at minor computational cost, which shows great potential for the design of micro- and nanomechanical devices and systems.

  7. Nonlinear resonances of a single-wall carbon nanotube cantilever

    NASA Astrophysics Data System (ADS)

    Kim, I. K.; Lee, S. I.

    2015-03-01

    The dynamics of an electrostatically actuated carbon nanotube (CNT) cantilever are discussed by theoretical and numerical approaches. Electrostatic and intermolecular forces between the single-walled CNT and a graphene electrode are considered. The CNT cantilever is analyzed by the Euler-Bernoulli beam theory, including its geometric and inertial nonlinearities, and a one-mode projection based on the Galerkin approximation and numerical integration. Static pull-in and pull-out behaviors are adequately represented by an asymmetric two-well potential with the total potential energy consisting of the CNT elastic energy, electrostatic energy, and the Lennard-Jones potential energy. Nonlinear dynamics of the cantilever are simulated under DC and AC voltage excitations and examined in the frequency and time domains. Under AC-only excitation, a superharmonic resonance of order 2 occurs near half of the primary frequency. Under both DC and AC loads, the cantilever exhibits linear and nonlinear primary and secondary resonances depending on the strength of the excitation voltages. In addition, the cantilever has dynamic instabilities such as periodic or chaotic tapping motions, with a variation of excitation frequency at the resonance branches. High electrostatic excitation leads to complex nonlinear responses such as softening, multiple stability changes at saddle nodes, or period-doubling bifurcation points in the primary and secondary resonance branches.

  8. Suspended single-walled carbon nanotube fluidic sensors.

    PubMed

    Son, B H; Park, Ji-Yong; Lee, Soonil; Ahn, Y H

    2015-10-07

    In this paper, we demonstrate the fabrication of liquid flow sensors employing partially suspended single-walled carbon nanotubes (SWNTs). We have found that the sign of the conductance change in SWNT flow sensors is not influenced by the direction of water flow for both supported and suspended devices. Therefore, the streaming potential is not the principal mechanism of the SWNT sensor response. Instead, the conductance change is more likely due to a reduction in the cation density in the electrical double layer, whose equilibrium conditions are determined by the liquid flow rate. More importantly, we have found that the sensitivity of suspended SWNT devices is more than 10 times greater than that of supported SWNT devices. A reduced screening effect and an increase in effective sensing volume are responsible for the enhanced sensitivity, which is consistent with the ion depletion model. We also have measured conductance as a function of gate bias at different flow rates and have determined the flow-rate dependent effective charge density, which influences the electrostatic configuration around SWNT devices.

  9. Hypergolic fuel detection using individual single walled carbon nanotube networks

    NASA Astrophysics Data System (ADS)

    Desai, S. C.; Willitsford, A. H.; Sumanasekera, G. U.; Yu, M.; Tian, W. Q.; Jayanthi, C. S.; Wu, S. Y.

    2010-06-01

    Accurate and reliable detection of hypergolic fuels such as hydrazine (N2H4) and its derivatives is vital to missile defense, aviation, homeland security, and the chemical industry. More importantly these sensors need to be capable of operation at low temperatures (below room temperature) as most of the widely used chemical sensors operate at high temperatures (above 300 °C). In this research a simple and highly sensitive single walled carbon nanotube (SWNT) network sensor was developed for real time monitoring of hydrazine leaks to concentrations at parts per million levels. Upon exposure to hydrazine vapor, the resistance of the air exposed nanotubes (p-type) is observed to increase rapidly while that of the vacuum-degassed nanotubes (n-type) is observed to decrease. It was found that the resistance of the sample can be recovered through vacuum pumping and exposure to ultraviolet light. The experimental results support the electrochemical charge transfer mechanism between the oxygen redox couple of the ambient and the Fermi level of the SWNT. Theoretical results of the hydrazine-SWNT interaction are compared with the experimental observations. It was found that a monolayer of water molecules on the SWNT is necessary to induce strong interactions between hydrazine and the SWNT by way of introducing new occupied states near the bottom of the conduction band of the SWNT.

  10. A single-walled carbon nanotube network gas sensing device.

    PubMed

    Wang, Li-Chun; Tang, Kea-Tiong; Teng, I-Ju; Kuo, Cheng-Tzu; Ho, Cheng-Long; Kuo, Han-Wen; Su, Tseng-Hsiung; Yang, Shang-Ren; Shi, Gia-Nan; Chang, Chang-Ping

    2011-01-01

    The goal of this research was to develop a chemical gas sensing device based on single-walled carbon nanotube (SWCNT) networks. The SWCNT networks are synthesized on Al(2)O(3)-deposted SiO(2)/Si substrates with 10 nm-thick Fe as the catalyst precursor layer using microwave plasma chemical vapor deposition (MPCVD). The development of interconnected SWCNT networks can be exploited to recognize the identities of different chemical gases by the strength of their particular surface adsorptive and desorptive responses to various types of chemical vapors. The physical responses on the surface of the SWCNT networks cause superficial changes in the electric charge that can be converted into electronic signals for identification. In this study, we tested NO(2) and NH(3) vapors at ppm levels at room temperature with our self-made gas sensing device, which was able to obtain responses to sensitivity changes with a concentration of 10 ppm for NO(2) and 24 ppm for NH(3).

  11. Endohedral Volume Control for Improved Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Campo, Jochen; Fagan, Jeffrey

    Liquid-phase processing of single-wall carbon nanotubes (SWCNTs) generally results in the exposure of their core volumes to the environment (opening) due to energy input necessary for purification and solubilization. For aqueous processing this results in SWCNTs routinely getting filled with water, which is detrimental to several properties. Importantly, water filling leads to significant redshifts to, and inhomogeneous broadening of, the electronic transitions of the SWCNTs, as well as a substantial decrease to their fluorescence quantum efficiency. Selection of (remaining) empty (end-capped) SWCNTs to avoid these adverse effects is possible by means of ultracentrifugation, but is a natively low yield process. In this work, SWCNTs are prefilled with linear alkanes or similar organic compounds, serving as a passive, highly homogeneous spacer, blocking the ingestion of water and hence preventing the detrimental consequences. Moreover, the low dielectric nature of the alkane core only weakly affects the local electronic wavefunction of the SWCNTs, effectively simulating empty core conditions and hence yielding much more resolved optical spectra with blue shifted peak positions compared to water filled SWCNTs. It is demonstrated that a wide variety of linear as well as cyclic alkanes can be applied for this purpose, in combination with various SWCNT materials.

  12. On the Stability and Abundance of Single Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Hedman, Daniel; Reza Barzegar, Hamid; Rosén, Arne; Wågberg, Thomas; Andreas Larsson, J.

    2015-11-01

    Many nanotechnological applications, using single-walled carbon nanotubes (SWNTs), are only possible with a uniform product. Thus, direct control over the product during chemical vapor deposition (CVD) growth of SWNT is desirable, and much effort has been made towards the ultimate goal of chirality-controlled growth of SWNTs. We have used density functional theory (DFT) to compute the stability of SWNT fragments of all chiralities in the series representing the targeted products for such applications, which we compare to the chiralities of the actual CVD products from all properly analyzed experiments. From this comparison we find that in 84% of the cases the experimental product represents chiralities among the most stable SWNT fragments (within 0.2 eV) from the computations. Our analysis shows that the diameter of the SWNT product is governed by the well-known relation to size of the catalytic nanoparticles, and the specific chirality is normally determined by the product’s relative stability, suggesting thermodynamic control at the early stage of product formation. Based on our findings, we discuss the effect of other experimental parameters on the chirality of the product. Furthermore, we highlight the possibility to produce any tube chirality in the context of recent published work on seeded-controlled growth.

  13. On the Stability and Abundance of Single Walled Carbon Nanotubes

    PubMed Central

    Hedman, Daniel; Reza Barzegar, Hamid; Rosén, Arne; Wågberg, Thomas; Andreas Larsson, J.

    2015-01-01

    Many nanotechnological applications, using single-walled carbon nanotubes (SWNTs), are only possible with a uniform product. Thus, direct control over the product during chemical vapor deposition (CVD) growth of SWNT is desirable, and much effort has been made towards the ultimate goal of chirality-controlled growth of SWNTs. We have used density functional theory (DFT) to compute the stability of SWNT fragments of all chiralities in the series representing the targeted products for such applications, which we compare to the chiralities of the actual CVD products from all properly analyzed experiments. From this comparison we find that in 84% of the cases the experimental product represents chiralities among the most stable SWNT fragments (within 0.2 eV) from the computations. Our analysis shows that the diameter of the SWNT product is governed by the well-known relation to size of the catalytic nanoparticles, and the specific chirality is normally determined by the product’s relative stability, suggesting thermodynamic control at the early stage of product formation. Based on our findings, we discuss the effect of other experimental parameters on the chirality of the product. Furthermore, we highlight the possibility to produce any tube chirality in the context of recent published work on seeded-controlled growth. PMID:26581125

  14. Bulk Mechanical Properties of Single Walled Carbon Nanotube Electrodes

    NASA Astrophysics Data System (ADS)

    Giarra, Matthew; Landi, Brian; Cress, Cory; Raffaelle, Ryne

    2007-03-01

    The unique properties of single walled carbon nanotubes (SWNTs) make them especially well suited for use as electrodes in power devices such as lithium ion batteries, hydrogen fuel cells, solar cells, and supercapacitors. The performances of such devices are expected to be influenced, at least in part, by the mechanical properties of the SWNTs used in composites or in stand alone ``papers.'' Therefore, the elastic moduli and ultimate tensile strengths of SWNT papers were measured as functions of temperature, SWNT purity, SWNT length, and SWNT bundling. The SWNTs used to produce the papers were synthesized in an alexandrite laser vaporization reactor at 1100^oC and purified using conventional acid-reflux conditions. Characterization of the SWNTs was performed using SEM, BET, TGA, and optical and Raman spectroscopy. The purified material was filtered and dried to yield papers of bundled SWNTs which were analyzed using dynamic mechanical analysis (DMA). It was observed that the mechanical properties of acid-refluxed SWNT papers were significantly improved by controlled thermal oxidation and strain-hardening. Elastic moduli of SWNT papers were measured between 3 and 6 GPa. Ultimate (breaking) tensile stresses were measured between 45 and 90 MPa at 1-3% strain. These results and their implications in regard to potential applications in power devices will be discussed.

  15. Dielectric properties of water inside single-walled carbon nanotubes.

    PubMed

    Mikami, Fuminori; Matsuda, Kazuyuki; Kataura, Hiromichi; Maniwa, Yutaka

    2009-05-26

    In this paper, we report novel ferroelectric properties of a new form of ice inside single-walled carbon nanotubes (SWCNTs). These are called "ice nanotubes" (ice NTs) and they consist of polygonal water rings stacked one-dimensionally along the SWCNT axis. We performed molecular dynamics (MD) calculations for the ice NTs under an external electric field and in a temperature range between 100 and 350 K. It is revealed that ice NTs show stepwise polarization with a significant hysteresis loop as a function of the external field strength. In particular, pentagonal and heptagonal ice NTs are found to be the world's smallest ferroelectrics with spontaneous polarization of around 1 microC/cm(2). The n-gonal ice NT, where n = 5, 6, or 7, has (n + 1)-polarized structures with different polarizations. These findings suggest potential applications of SWCNTs encapsulating dielectric materials for the fabrication of the smallest ferroelectric devices. Experimental evidence for the presence of ice NTs inside SWCNTs is also discussed in great detail.

  16. Buckling of single-walled carbon nanotubes using two criteria

    NASA Astrophysics Data System (ADS)

    Gupta, Shakti S.; Agrawal, Pranav; Batra, Romesh C.

    2016-06-01

    We use molecular mechanics simulations with the MM3 potential to study instabilities in clamped-clamped single-walled carbon nanotubes (SWCNTs) deformed in torsion and axial compression. The following are the two criteria employed to find the critical buckling strain: (i) a sudden drop in the potential energy and (ii) an eigenvalue of the mass weighted Hessian of the deformed configuration becoming zero. The instability under axial compression is investigated for zigzag and armchair SWCNTs, and that under torsional deformations is also studied for chiral tubes. In general, values of critical strains from the 2nd criterion are found to be substantially less than those from the 1st criterion. For chiral SWCNTs, the critical strains from the 2nd criterion and the potential energies at the onset of instability markedly depend upon the twisting direction. Values of buckling strains predicted from the column and the shell buckling theories are found to agree well with those obtained using the 2nd criterion.

  17. A Single-Walled Carbon Nanotube Network Gas Sensing Device

    PubMed Central

    Wang, Li-Chun; Tang, Kea-Tiong; Teng, I-Ju; Kuo, Cheng-Tzu; Ho, Cheng-Long; Kuo, Han-Wen; Su, Tseng-Hsiung; Yang, Shang-Ren; Shi, Gia-Nan; Chang, Chang-Ping

    2011-01-01

    The goal of this research was to develop a chemical gas sensing device based on single-walled carbon nanotube (SWCNT) networks. The SWCNT networks are synthesized on Al2O3-deposted SiO2/Si substrates with 10 nm-thick Fe as the catalyst precursor layer using microwave plasma chemical vapor deposition (MPCVD). The development of interconnected SWCNT networks can be exploited to recognize the identities of different chemical gases by the strength of their particular surface adsorptive and desorptive responses to various types of chemical vapors. The physical responses on the surface of the SWCNT networks cause superficial changes in the electric charge that can be converted into electronic signals for identification. In this study, we tested NO2 and NH3 vapors at ppm levels at room temperature with our self-made gas sensing device, which was able to obtain responses to sensitivity changes with a concentration of 10 ppm for NO2 and 24 ppm for NH3. PMID:22164044

  18. Potassium-Decorated, Single-Wall Carbon Nanotubes.

    NASA Astrophysics Data System (ADS)

    Rao, A. M.; Richter, E.; Menon, M.; Subbaswamy, K. R.; Eklund, P. C.; Thess, A.; Smalley, R. E.

    1997-03-01

    Crystalline ropes of single-wall carbon nanotubes have been reacted in sealed glass tubes with potassium vapor and Raman scattering has been used to monitor the vibrational modes as a function of reaction time. An overall broadening and downshifting of the Raman bands is observed. For example, huge downshifts (40 cm-1) in the high frequency tangential modes observed near 1593 cm-1 in the pristine tubes are detected. These downshifts are attributed to significant charge transfer of K 4s electrons into antibonding pz states of the nanotube which should expand the tube diameter and soften the lattice. Presumably, the potassium ions are chemisorbed onto the walls of the nanotubes, rather than inside the nanotube, although no structural information to support this model has yet been collected. Theoretical results on electron doped armchair symmetry nanotubes using the Generalized Tight Binding Molecular Dynamics model will also be presented to help explain experimental results. The Kentucky group was supported by the University of Kentucky Center for Applied Energy Research and NSF Grant No. OSR-94-52895 and DOE Contract No. DE-F22-90PC90029. The work at Rice was supported by the Office of Naval Research Contract N0014-91-J1794.

  19. Hypergolic fuel detection using individual single walled carbon nanotube networks

    SciTech Connect

    Desai, S. C.; Willitsford, A. H.; Sumanasekera, G. U.; Yu, M.; Jayanthi, C. S.; Wu, S. Y.; Tian, W. Q.

    2010-06-15

    Accurate and reliable detection of hypergolic fuels such as hydrazine (N{sub 2}H{sub 4}) and its derivatives is vital to missile defense, aviation, homeland security, and the chemical industry. More importantly these sensors need to be capable of operation at low temperatures (below room temperature) as most of the widely used chemical sensors operate at high temperatures (above 300 deg. C). In this research a simple and highly sensitive single walled carbon nanotube (SWNT) network sensor was developed for real time monitoring of hydrazine leaks to concentrations at parts per million levels. Upon exposure to hydrazine vapor, the resistance of the air exposed nanotubes (p-type) is observed to increase rapidly while that of the vacuum-degassed nanotubes (n-type) is observed to decrease. It was found that the resistance of the sample can be recovered through vacuum pumping and exposure to ultraviolet light. The experimental results support the electrochemical charge transfer mechanism between the oxygen redox couple of the ambient and the Fermi level of the SWNT. Theoretical results of the hydrazine-SWNT interaction are compared with the experimental observations. It was found that a monolayer of water molecules on the SWNT is necessary to induce strong interactions between hydrazine and the SWNT by way of introducing new occupied states near the bottom of the conduction band of the SWNT.

  20. Single walled carbon nanotube composites for bone tissue engineering.

    PubMed

    Gupta, Ashim; Woods, Mia D; Illingworth, Kenneth David; Niemeier, Ryan; Schafer, Isaac; Cady, Craig; Filip, Peter; El-Amin, Saadiq F

    2013-09-01

    The purpose of this study was to develop single walled carbon nanotubes (SWCNT) and poly lactic-co-glycolic acid (PLAGA) composites for orthopedic applications and to evaluate the interaction of human stem cells (hBMSCs) and osteoblasts (MC3T3-E1 cells) via cell growth, proliferation, gene expression, extracellular matrix production and mineralization. PLAGA and SWCNT/PLAGA composites were fabricated with various amounts of SWCNT (5, 10, 20, 40, and 100 mg), characterized and degradation studies were performed. Cells were seeded and cell adhesion/morphology, growth/survival, proliferation and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated uniform incorporation of SWCNT into the PLAGA matrix and addition of SWCNT did not affect the degradation rate. Imaging studies revealed that MC3T3-E1 and hBMSCs cells exhibited normal, non-stressed morphology on the composites and all were biocompatible. Composites with 10 mg SWCNT resulted in highest rate of cell proliferation (p < 0.05) among all composites. Gene expression of alkaline phosphatase, collagen I, osteocalcin, osteopontin, Runx-2, and Bone Sialoprotein was observed on all composites. In conclusion, SWCNT/PLAGA composites imparted beneficial cellular growth capabilities and gene expression, and mineralization abilities were well established. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration and bone tissue engineering (BTE) and are promising for orthopedic applications.

  1. Reinforced Thermoplastic Polyimide with Dispersed Functionalized Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Lebron-Colon, Marisabel; Meador, Michael A.; Gaier, James R.; Sola, Francisco; Scheiman, Daniel A.; McCorkle, Linda S.

    2010-01-01

    Molecular pi-complexes were formed from pristine HiPCO single-wall carbon nanotubes (SWCNTs) and 1-pyrene- N-(4- N'-(5-norbornene-2,3-dicarboxyimido)phenyl butanamide, 1. Polyimide films were prepared with these complexes as well as uncomplexed SWCNTs and the effects of nanoadditive addition on mechanical, thermal, and electrical properties of these films were evaluated. Although these properties were enhanced by both nanoadditives, larger increases in tensile strength and thermal and electrical conductivities were obtained when the SWCNT/1 complexes were used. At a loading level of 5.5 wt %, the Tg of the polyimide increased from 169 to 197 C and the storage modulus increased 20-fold (from 142 to 3045 MPa). The addition of 3.5 wt % SWCNT/1 complexes increased the tensile strength of the polyimide from 61.4 to 129 MPa; higher loading levels led to embrittlement and lower tensile strengths. The electrical conductivities (DC surface) of the polyimides increased to 1 x 10(exp -4) Scm(exp -1) (SWCNT/1 complexes loading level of 9 wt %). Details of the preparation of these complexes and their effects on polyimide film properties are discussed.

  2. Extinction coefficients and purity of single-walled carbon nanotubes.

    PubMed

    Zhao, B; Itkis, M E; Niyogi, S; Hu, H; Perea, D E; Haddon, R C

    2004-11-01

    Single-walled carbon nanotubes (SWNTs) hold great promise for advanced applications in aerospace, electronics and medicine, yet these industries require materials with rigorous quality control. There are currently no accepted standards for quality assurance or quality control among the commercial suppliers of SWNTs. We briefly discuss the applicability of various techniques to measure SWNT purity and review, in detail, the advantages of near infrared (NIR) spectroscopy for the quantitative assessment of the bulk carbonaceous purity of SWNTs. We review the use of solution phase NIR spectroscopy for the analysis and characterization of a variety of carbon materials, emphasizing SWNTs produced by the electric arc (EA), laser oven (LO) and HiPco (HC) methods. We consider the applicability of Beer's law to carbon materials dispersed in dimethylformamide (DMF) and the effective extinction coefficients that are obtained from such dispersions. Analysis of the areal absorptivities of the second interband transition of semiconducting EA-produced SWNTs for a number of samples of differing purities has lead to an absolute molar extinction coefficient for the carbonaceous impurities in EA-produced SWNT samples. We conclude that NIR spectroscopy is the clear method of choice for the assessment of the bulk carbonaceous purity of EA-produced SWNTs, and we suggest that an absolute determination of the purity of SWNTs is within reach. Continued work in this area is expected to lead to a universal method for the assessment of the absolute bulk purity of SWNTs from all sources--such a development will be of great importance for nanotube science and for future customers for this product.

  3. Direct Synthesis of Long Single-Walled Carbon Nanotube Strands

    NASA Astrophysics Data System (ADS)

    Zhu, H. W.; Xu, C. L.; Wu, D. H.; Wei, B. Q.; Vajtai, R.; Ajayan, P. M.

    2002-05-01

    In the processes that are used to produce single-walled nanotubes (electric arc, laser ablation, and chemical vapor deposition), the typical lengths of tangled nanotube bundles reach several tens of micrometers. We report that long nanotube strands, up to several centimeters in length, consisting of aligned single-walled nanotubes can be synthesized by the catalytic pyrolysis of n-hexane with an enhanced vertical floating technique. The long strands of nanotubes assemble continuously from arrays of nanotubes, which are intrinsically long.

  4. Electronic Durability of Flexible Transparent Films from Type-Specific Single-Wall Carbon Nanotubes

    SciTech Connect

    Harris, J; Iyer, S; Bernhardt, A; Huh, JY; Hudson, S; Fagan, J; Hobbie, E.

    2011-12-11

    The coupling between mechanical flexibility and electronic performance is evaluated for thin films of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) deposited on compliant supports. Percolated networks of type-purified SWCNTs are assembled as thin conducting coatings on elastic polymer substrates, and the sheet resistance is measured as a function of compression and cyclic strain through impedance spectroscopy. The wrinkling topography, microstructure and transparency of the films are independently characterized using optical microscopy, electron microscopy, and optical absorption spectroscopy. Thin films made from metallic SWCNTs show better durability as flexible transparent conductive coatings, which we attribute to a combination of superior mechanical performance and higher interfacial conductivity.

  5. Red-emitting π-conjugated oligomers infused single-wall carbon nanotube sheets

    NASA Astrophysics Data System (ADS)

    Fujimori, Toshihiko; Urita, Koki

    2016-04-01

    We demonstrate the one-step thermal fusion and infusion of pyrene molecules inside single-wall carbon nanotubes (SWCNTs). Despite the presence of metallic-SWCNTs, which behave as a quencher due to gapless electronic states, the nanohybrids consisting of pyrene and/or azupyrene oligomers infused SWCNT sheets exhibit red fluorescence by the ultraviolet, blue, and green light excitations. The wavelength-independent light-emitting behavior is explained by (1) infused PAH oligomers inside semiconducting-SWCNTs and (2) the peculiar π-π interaction through mixed π-conjugated state between the π-conjugated oligomers and non-armchair metallic-SWCNTs.

  6. Nano-electromechanical displacement sensing based on single-walled carbon nanotubes.

    PubMed

    Stampfer, C; Jungen, A; Linderman, R; Obergfell, D; Roth, S; Hierold, C

    2006-07-01

    We present a nano-electromechanical system based on an individual single-walled carbon nanotube (SWNT) demonstrating their potential use for future displacement sensing at the nanoscale. The fabrication and characterization of the proposed nanoscaled transducer, consisting of a suspended metal cantilever mounted on top of the center of a suspended SWNT, is presented and discussed. The displacement of the nanoscale cantilever is detected via the electromechanically induced change in conductance of the strained SWNT. A relative differential resistance sensitivity (for a metallic SWNT) of up to 27.5%/nm was measured and a piezoresistive gauge factor of a SWNT of up to 2900 was extracted.

  7. Effects of single-walled carbon nanotubes on soil microorganisms

    NASA Astrophysics Data System (ADS)

    Jin, L.; Chung, H.; Son, Y.

    2011-12-01

    Single-walled carbon nanotubes (SWCNTs) are novel materials that have the potential to be used in various commercial fields due to their unique physicochemical properties. As a result of commercial development of nanotechnology, SWCNTs may be discharged to the soil environment with unknown consequences. However, there are as yet no data in the scientific literature that demonstrate the effects of SWCNTs on microbial function in soils. Therefore, we aimed to determine the effects of SWCNTs on soil microbial activity through a 2-week incubation study on urban soils supplemented with different concentrations of SWCNTs ranging from 0 to 1000 μg CNT/g soil. Fluorometric test using fluorogenic substrates were employed for the measurement of several enzyme activities in soil samples. More specifically, we determined the changes in the activities of cellobiohydrolase, β-1,4-glucosidase, β-1,4-xylosidase, β-1,4-N-acetylglucosaminidase, L-leucine aminopeptidase and acid phosphatase which play important roles in the carbon, nitrogen, and phosphorus cycles in response to the addition of SWCNTs. We found that microbial enzyme activities decreased as the concentrations of SWCNT added increased. The lowest enzyme activities were observed under 1000 μg CNT/g soil. The overall pattern shows that enzyme activities decreased slightly in the first 2-3 days and increased in the later stage of the incubation. Our results suggest that relatively high concentrations of SWCNTs can inhibit microbial activities, and this may be due to microbial cell membrane damage caused by SWCNTs. However, further study needs to be conducted to determine the mechanism responsible for inhibitory effect of SWCNTs on soil microbial activity. It can be concluded that changes in the activities of extracellular enzymes can indicate the effect of SWCNTs on soil microorganisms and nutrient cycling.

  8. Elastomer Filled With Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Files, Bradley S.; Forest, Craig R.

    2004-01-01

    Experiments have shown that composites of a silicone elastomer with single-wall carbon nanotubes (SWNTs) are significantly stronger and stiffer than is the unfilled elastomer. The large strengthening and stiffening effect observed in these experiments stands in contrast to the much smaller strengthening effect observed in related prior efforts to reinforce epoxies with SWNTs and to reinforce a variety of polymers with multiple-wall carbon nanotubes (MWNTs). The relative largeness of the effect in the case of the silicone-elastomer/SWNT composites appears to be attributable to (1) a better match between the ductility of the fibers and the elasticity of the matrix and (2) the greater tensile strengths of SWNTs, relative to MWNTs. For the experiments, several composites were formulated by mixing various proportions of SWNTs and other filling materials into uncured RTV-560, which is a silicone adhesive commonly used in aerospace applications. Specimens of a standard "dog-bone" size and shape for tensile testing were made by casting the uncured elastomer/filler mixtures into molds, curing the elastomer, then pressing the specimens from a "cookie-cutter" die. The results of tensile tests of the specimens showed that small percentages of SWNT filler led to large increases in stiffness and tensile strength, and that these increases were greater than those afforded by other fillers. For example, the incorporation of SWNTs in a proportion of 1 percent increased the tensile strength by 44 percent and the modulus of elasticity (see figure) by 75 percent. However, the relative magnitudes of the increases decreased with increasing nanotube percentages because more nanotubes made the elastomer/nanotube composites more brittle. At an SWNT content of 10 percent, the tensile strength and modulus of elasticity were 125 percent and 562 percent, respectively, greater than the corresponding values for the unfilled elastomer.

  9. Photovoltaic device using single wall carbon nanotubes and method of fabricating the same

    DOEpatents

    Biris, Alexandru S.; Li, Zhongrui

    2012-11-06

    A photovoltaic device and methods for forming the same. In one embodiment, the photovoltaic device has a silicon substrate, and a film comprising a plurality of single wall carbon nanotubes disposed on the silicon substrate, wherein the plurality of single wall carbon nanotubes forms a plurality of heterojunctions with the silicon in the substrate.

  10. Single-walled carbon nanotubes as near-infrared optical biosensors for life sciences and biomedicine.

    PubMed

    Jain, Astha; Homayoun, Aida; Bannister, Christopher W; Yum, Kyungsuk

    2015-03-01

    Single-walled carbon nanotubes that emit photostable near-infrared fluorescence have emerged as near-infrared optical biosensors for life sciences and biomedicine. Since the discovery of their near-infrared fluorescence, researchers have engineered single-walled carbon nanotubes to function as an optical biosensor that selectively modulates its fluorescence upon binding of target molecules. Here we review the recent advances in the single-walled carbon nanotube-based optical sensing technology for life sciences and biomedicine. We discuss the structure and optical properties of single-walled carbon nanotubes, the mechanisms for molecular recognition and signal transduction in single-walled carbon nanotube complexes, and the recent development of various single-walled carbon nanotube-based optical biosensors. We also discuss the opportunities and challenges to translate this emerging technology into biomedical research and clinical use, including the biological safety of single-walled carbon nanotubes. The advances in single-walled carbon nanotube-based near-infrared optical sensing technology open up a new avenue for in vitro and in vivo biosensing with high sensitivity and high spatial resolution, beneficial for many areas of life sciences and biomedicine.

  11. Study on the Microwave Permittivity of Single-Walled Carbon Nanotube

    ERIC Educational Resources Information Center

    Liu, Xiaolai; Zhao, Donglin

    2009-01-01

    In this article, we studied the microwave permittivity of the complex of the single-walled carbon nanotube and paraffin in 2-18GHz. In the range, the dielectric loss of single-walled carbon nanotube is higher, and the real part and the imaginary part of the dielectric constant decrease with the increase of frequency, and the dielectric constant…

  12. Chirality affects aggregation kinetics of single-walled carbon nanotubes.

    PubMed

    Khan, Iftheker A; Afrooz, A R M Nabiul; Flora, Joseph R V; Schierz, P Ariette; Ferguson, P Lee; Sabo-Attwood, Tara; Saleh, Navid B

    2013-02-19

    Aggregation kinetics of chiral-specific semiconducting single-walled carbon nanotubes (SWNTs) was systematically studied through time-resolved dynamic light scattering. Varied monovalent (NaCl) and divalent (CaCl(2)) electrolyte composition was used as background solution chemistry. Suwannee River humic acid (SRHA) was used to study the effects of natural organic matter on chirally separated SWNT aggregation. Increasing salt concentration and introduction of divalent cations caused aggregation of SWNT clusters by suppressing the electrostatic repulsive interaction from the oxidized surfaces. The (6,5) SWNTs, i.e., SG65, with relatively lower diameter tubes compared to (7,6), i.e., SG76, showed substantially higher stability (7- and 5-fold for NaCl and CaCl(2), respectively). The critical coagulation concentration (CCC) values were 96 and 13 mM NaCl in the case of NaCl and 2.8 and 0.6 mM CaCl(2) for SG65 and SG76, respectively. The increased tube diameter for (7,6) armchair SWNTs likely presented with higher van der Waals interaction and thus increased the aggregation propensity substantially. The presence of SRHA enhanced SWNT stability in divalent CaCl(2) environment through steric interaction from adsorbed humic molecules; however showed little or no effects for monovalent NaCl. The mechanism of aggregation-describing favorable interaction tendencies for (7,6) SWNTs-is probed through ab initio molecular modeling. The results suggest that SWNT stability can be chirality dependent in typical aquatic environment.

  13. Polymer grafted single-walled carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Viswanathan, Gunaranjan

    The quasi one-dimensional structure, aspect ratio, mechanical strength and electrical properties of single-walled carbon nanotubes make them ideal fillers for incorporation into composite systems for the development of advanced multifunctional materials. But several issues, including dispersion of nanotubes within the matrix, exfoliation of nanotube bundles and interaction of nanotubes with the host polymer, have to be addressed in order to realize the true potential of these composites. Especially for applications as structural reinforcements, the interface between the nanotubes and the polymer has to be engineered in order to maximize load transfer. The best way of ensuring favorable matrix-nanotube interactions is by chemical functionalization of the nanotube surface with suitable groups to promote adhesion with the polymer matrix. Functionalizing nanotubes with the polymer of the matrix provides the ideal case scenario by offering the best possible interface with the host polymer. The work presented in this thesis involves the development of a novel methodology based on an anionic polymerization approach, for the synthesis of polymer-grafted nanotube based composites, with the aim of improving the dispersion of nanotubes and the interfacial adhesion between the nanotubes and the matrix polymer. This technique enables single-step synthesis, requires no nanotube pretreatment and preserves the original nanotube structure. Significant improvements in the mechanical properties of composites containing polymer-grafted nanotubes (when compared to both pure polymer and composites containing unfunctionalized nanotubes) were observed even at low nanotube loadings (1 wt.%). Melt-state rheological studies revealed changes in the terminal and entanglement plateau regions due to interactions between the free and grafted polymer chains. The improved load transfer across the fiber-matrix interface was confirmed using Raman spectroscopy.

  14. Superemission in vertically-aligned single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Khmelinskii, Igor; Makarov, Vladimir

    2016-09-01

    Presently we used two samples of vertically aligned single-wall carbon nanotubes (VA SWCNTs) with parallelepiped geometry, sized 0.02 cm × 0.2 cm × 1.0 cm and 0.2 cm × 0.2 cm × 1.0 cm. We report absorption and emission properties of the VA SWCNTs, including strong anisotropy in both their absorption and emission spectra. We found that the emission spectra extend from the middle-IR range to the near-IR range, with such extended spectra being reported for the first time. Pumping the VA SWCNTs in the direction normal to their axis, superemission (SE) was observed in the direction along their axis. The SE band maximum is located at 7206 ± 0.4 cm-1. The energy and the power density of the superemission were estimated, along with the diffraction-limited divergence. At the pumping energy of 3 mJ/pulse, the SE energy measured by the detector was 0.74 mJ/pulse, corresponding to the total SE energy of 1.48 mJ/pulse, with the energy density of 18.5 mJ cm-2/pulse and the SE power density of 1.2 × 105 W cm-2/pulse. We report that a bundle of VA SWCNTs is an emitter with a relatively small divergence, not exceeding 3.9 × 10-3 rad. We developed a theoretical approach to explain such absorption and emission spectra. The developed theory is based on the earlier proposed SSH theory, which we extended to include the exchange interactions between the closest SWCNT neighbors. The developed theoretical ideas were implemented in a homemade FORTRAN code. This code was successfully used to calculate and reproduce the experimental spectra and to determine the SWCNT species that originate the respective absorption bands, with acceptable agreement between theory and experiment.

  15. Decarboxylation of oxidized single-wall carbon nanotubes.

    PubMed

    Vieira, H S; Andrada, D M; Mendonça, R; Santos, A P; Martins, M D; Macedo, W A A; Gorgulho, H F; Pimenta, L P S; Moreira, R L; Jorio, A; Pimenta, M A; Furtado, C A

    2007-10-01

    A classical protocol widely used in organic chemistry of aromatic and polyaromatic molecules has been successfully applied in this work for the decarboxylation of oxidized single-wall carbon nanotube (SWNT) to rend C-H SWNT derivatives. SWNT produced by arc discharge method have been oxidized during a purification process using strongly oxidant agents, such as hydrogen peroxide and nitric acid. The decarboxylation of oxidized SWNT has been conduced with copper(I) oxide in a 50:50 solution of N-methylpyrrolidone and quinoline. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and acid-base potentiometric titration analyses were carried out to characterize quali and quantitatively the changes in the chemical environment on the SWNT surface in each step of the purification and the decarboxylation process. Those techniques showed the appearance of mainly carboxylic and phenolic groups after the purification process and the disappearance of the carboxylic groups after the decarboxylation reaction. Fourier transform infrared spectroscopy analysis indicated also the formation of aliphatic and aromatic C-H groups. X-ray photoelectron spectroscopy and potentiometric titration results determined an efficiency higher than 90% for our decarboxylation procedure. The purity and structural quality of the SWNT sample used in the decarboxylation process were evaluated by thermogravimetry and Raman spectroscopy. Thermogravimetric analysis identified a purified sample with approximately 80 wt% of SWNT, in fractions distributed in highly structured SWNTs (25 wt%), with distribution in composition, length and structural quality (35 wt%) and with very defective and short tubes (25 wt%). The damages on the purified SWNT walls were characterized by the Raman scattering analysis.

  16. Toroidal Single Wall Carbon Nanotubes in Fullerene Crop Circles

    NASA Technical Reports Server (NTRS)

    Han, Jie; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    We investigate energetics and structure of circular and polygonal single wall carbon nanotubes (SWNTs) using large scale molecular simulations on NAS SP2, motivated by their unusual electronic and magnetic properties. The circular tori are formed by bending tube (no net whereas the polygonal tori are constructed by turning the joint of two tubes of (n, n), (n+1, n-1) and (n+2, n-2) with topological pentagon-heptagon defect, in which n =5, 8 and 10. The strain energy of circular tori relative to straight tube decreases by I/D(sup 2) where D is torus diameter. As D increases, these tori change from buckling to an energetically stable state. The stable tori are perfect circular in both toroidal and tubular geometry with strain less than 0. 03 eV/atom when D greater than 10, 20 and 40 nm for torus (5,5), (8,8) and (10, 10). Polygonal tori, whose strain is proportional to the number of defects and I/D are energetically stable even for D less than 10 nm. However, their strain is higher than that of perfect circular tori. In addition, the local maximum strain of polygonal tori is much higher than that of perfect circular tori. It is approx. 0.03 eV/atom or less for perfect circular torus (5,5), but 0.13 and 0.21 eV/atom for polygonal tori (6,4)/(5,5) and (7,3)/(5,5). Therefore, we conclude that the circular tori with no topological defects are more energetically stable and kinetically accessible than the polygonal tori containing the pentagon-heptagon defects for the laser-grown SWNTs and Fullerene crop circles.

  17. Effect of atomic interconnects on percolation in single-walled carbon nanotube thin film networks.

    PubMed

    Tian, Xiaojuan; Moser, Matthew L; Pekker, Aron; Sarkar, Santanu; Ramirez, Jason; Bekyarova, Elena; Itkis, Mikhail E; Haddon, Robert C

    2014-07-09

    The formation of covalent bonds to single-walled carbon nanotube (SWNT) or graphene surfaces usually leads to a decrease in the electrical conductivity and mobility as a result of the structural rehybridization of the functionalized carbon atoms from sp(2) to sp(3). In the present study, we explore the effect of metal deposition on semiconducting (SC-) and metallic (MT-) SWNT thin films in the vicinity of the percolation threshold and we are able to clearly delineate the effects of weak physisorption, ionic chemisorption with charge transfer, and covalent hexahapto (η(6)) chemisorption on these percolating networks. The results support the idea that for those metals capable of forming bis-hexahapto-bonds, the generation of covalent (η(6)-SWNT)M(η(6)-SWNT) interconnects provides a conducting pathway in the SWNT films and establishes the transition metal bis-hexahapto organometallic bond as an electronically conjugating linkage between graphene surfaces.

  18. Single walled carbon nanotube networks as substrates for bone cells

    NASA Astrophysics Data System (ADS)

    Tutak, Wojtek

    A central effort in biomedical research concerns the development of materials for sustaining and controlling cell growth. Carbon nanotube based substrates have been shown to support the growth of different kinds of cells. However the underlying molecular mechanisms remain poorly defined. To address the fundamental question of mechanisms by which nanotubes promote bone mitosis and histogenesis, primary calvariae osteoblastic cells were grown on single walled carbon nanotube (SWNT) network substrates. Using a combination of biochemical and optical techniques, we demonstrate here that SWNT networks promote cell development through two distinct steps. Initially, SWNTs are absorbed in a process that resembles endocytosis, inducing acute toxicity. Nanotube mediated cell destruction, however, induces a release of endogenous factors that act to boost the activity of the surviving cells by stimulating the synthesis of extracellular matrix. In the second part of the research, minimally invasive SWNT matrices were used to further investigate network properties for biomedical applications without extensive presence of cytotoxicity. In the literature, carbon nanotube based substrates have been shown to support the growth of different cell types and, as such, have raised considerable interest in their possible use in biomedical applications. Nanotube matrices that are embedded in polymers cause inherent changes in nanotube chemical and physical film properties. Thus, it is critical to understand how the physical properties of the pristine networks affect the biology of the host tissue. Here, we investigated how the physical and chemical properties of SWNT networks impact the response of MC3T3-E1 bone osteoblasts. We found that two fundamental steps in cell growth: initial attachment to the substrate and proliferation, are strongly dependent on the energy and roughness of the surface, respectively. Thus, fine-tuning the properties of the film may represent a strategy to optimize

  19. Sequestration of Single-Walled Carbon Nanotubes in a Polymer

    NASA Technical Reports Server (NTRS)

    Bley, Richard A.

    2007-01-01

    Sequestration of single-walled carbon nanotubes (SWCNs) in a suitably chosen polymer is under investigation as a means of promoting the dissolution of the nanotubes into epoxies. The purpose of this investigation is to make it possible to utilize SWCNs as the reinforcing fibers in strong, lightweight epoxy-matrix/carbon-fiber composite materials. SWCNs are especially attractive for use as reinforcing fibers because of their stiffness and strength-to-weight ratio: Their Young s modulus has been calculated to be 1.2 TPa, their strength has been calculated to be as much as 100 times that of steel, and their mass density is only one-sixth that of steel. Bare SWCNs cannot be incorporated directly into composite materials of the types envisioned because they are not soluble in epoxies. Heretofore, SWCNS have been rendered soluble by chemically attaching various molecular chains to them, but such chemical attachments compromise their structural integrity. In the method now under investigation, carbon nanotubes are sequestered in molecules of poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) [PmPV]. The strength of the carbon nanotubes is preserved because they are not chemically bonded to the PmPV. This method exploits the tendency of PmPV molecules to wrap themselves around carbon nanotubes: the wrapping occurs partly because there exists a favorable interface between the conjugated face of a nanotube and the conjugated backbone of the polymer and partly because of the helical molecular structure of PmPV. The constituents attached to the polymer backbones (the side chains) render the PmPV-wrapped carbon nanotubes PmPV soluble in organic materials that, in turn, could be used to suspend the carbon nanotubes in epoxy precursors. At present, this method is being optimized: The side chains on the currently available form of PmPV are very nonpolar and unable to react with the epoxy resins and/or hardeners; as a consequence, SWCN/PmPV composites have been

  20. New Method Developed To Purify Single Wall Carbon Nanotubes for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Lebron, Marisabel; Meador, Michael A.

    2003-01-01

    Single wall carbon nanotubes have attracted considerable attention because of their remarkable mechanical properties and electrical and thermal conductivities. Use of these materials as primary or secondary reinforcements in polymers or ceramics could lead to new materials with significantly enhanced mechanical strength and electrical and thermal conductivity. Use of carbon-nanotube-reinforced materials in aerospace components will enable substantial reductions in component weight and improvements in durability and safety. Potential applications for single wall carbon nanotubes include lightweight components for vehicle structures and propulsion systems, fuel cell components (bipolar plates and electrodes) and battery electrodes, and ultra-lightweight materials for use in solar sails. A major barrier to the successful use of carbon nanotubes in these components is the need for methods to economically produce pure carbon nanotubes in large enough quantities to not only evaluate their suitability for certain applications but also produce actual components. Most carbon nanotube synthesis methods, including the HiPCO (high pressure carbon monoxide) method developed by Smalley and others, employ metal catalysts that remain trapped in the final product. These catalyst impurities can affect nanotube properties and accelerate their decomposition. The development of techniques to remove most, if not all, of these impurities is essential to their successful use in practical applications. A new method has been developed at the NASA Glenn Research Center to purify gram-scale quantities of single wall carbon nanotubes. This method, a modification of a gas phase purification technique previously reported by Smalley and others, uses a combination of high-temperature oxidations and repeated extractions with nitric and hydrochloric acid. This improved procedure significantly reduces the amount of impurities (catalyst and nonnanotube forms of carbon) within the nanotubes, increasing

  1. Flame Synthesis Of Single-Walled Carbon Nanotubes And Nanofibers

    NASA Technical Reports Server (NTRS)

    Wal, Randy L. Vander; Berger, Gordon M.; Ticich, Thomas M.

    2003-01-01

    Carbon nanotubes are widely sought for a variety of applications including gas storage, intercalation media, catalyst support and composite reinforcing material [1]. Each of these applications will require large scale quantities of CNTs. A second consideration is that some of these applications may require redispersal of the collected CNTs and attachment to a support structure. If the CNTs could be synthesized directly upon the support to be used in the end application, a tremendous savings in post-synthesis processing could be realized. Therein we have pursued both aerosol and supported catalyst synthesis of CNTs. Given space limitations, only the aerosol portion of the work is outlined here though results from both thrusts will be presented during the talk. Aerosol methods of SWNT, MWNT or nanofiber synthesis hold promise of large-scale production to supply the tonnage quantities these applications will require. Aerosol methods may potentially permit control of the catalyst particle size, offer continuous processing, provide highest product purity and most importantly, are scaleable. Only via economy of scale will the cost of CNTs be sufficient to realize the large-scale structural and power applications on both earth and in space. Present aerosol methods for SWNT synthesis include laser ablation of composite metalgraphite targets or thermal decomposition/pyrolysis of a sublimed or vaporized organometallic [2]. Both approaches, conducted within a high temperature furnace, have produced single-walled nanotubes (SWNTs). The former method requires sophisticated hardware and is inherently limited by the energy deposition that can be realized using pulsed laser light. The latter method, using expensive organometallics is difficult to control for SWNT synthesis given a range of gasparticle mixing conditions along variable temperature gradients; multi-walled nanotubes (MWNTs) are a far more likely end products. Both approaches require large energy expenditures and

  2. Electronic and Optical Properties of Single Wall Carbon Nanotubes.

    PubMed

    Saito, R; Nugraha, A R T; Hasdeo, E H; Hung, N T; Izumida, W

    2017-02-01

    In this article, we overview our recent theoretical works on electronic and optical properties of carbon nanotubes by going from the background to the perspectives. Electronic Raman spectra of metallic carbon nanotubes give a new picture of Raman processes. Thermoelectricity of semiconducting nanotubes gives a general concept of the confinement effect on the thermoelectric power factor. Selective excitation of only a single phonon mode is proposed by the pulsed train technique of coherent phonon spectroscopy. Occurrence of both two and four fold degeneracy in the carbon nanotube quantum dot is explained by difference group velocities and the intra/inter valley scattering near the hexagonal corner of the Brillouin zone.

  3. Synthesis of Single-Walled Carbon Nanotubes in a Glow Discharge Fine Particle Plasma

    SciTech Connect

    Imazato, N.; Imano, M.; Hayashi, Y.

    2008-09-07

    Carbon fine particles were synthesized being negatively charged and confined in a glow discharge plasma. The deposited fine particles were analyzed by Raman spectroscopy and transmission electron microscopy (TEM) and were confirmed to include single-walled carbon nanotubes.

  4. Fast Characterization of Magnetic Impurities in Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Chen, Feng; Xue, Y. Y.; Hadijiev, Viktor G.; Chu, C. W.; Nikolaev, Pasha; Arepalli, Sivaram

    2003-01-01

    We have demonstrated that the magnetic susceptibility measurement is a non-destructive, fast and accurate method to determine the residual metal catalysts in a few microgram single-wall carbon nanotube (SWCNT) sample. We have studied magnetic impurities in raw and purified SWCNT by magnetic susceptibility measurements, transmission electron microscopy, and thermogravimetry. The data suggest that the saturation magnetic moment and the effective field, which is caused by the interparticle interactions, decreases and increases respectively with the decrease of the particle size. Methods are suggested to overcome the uncertainty associated.

  5. Noncovalent functionalization of single-walled carbon nanotubes by aromatic diisocyanate molecules: A computational study

    NASA Astrophysics Data System (ADS)

    Goclon, Jakub; Kozlowska, Mariana; Rodziewicz, Pawel

    2014-04-01

    We investigate the noncovalent functionalization of metallic single-walled carbon nanotubes (SWCNT) (6,0) by 4,4‧-methylene diphenyl diisocyanate (MDI) and toluene-2,4-diisocyanate (TDI) molecules using the density functional theory (DFT) method with van der Waals dispersion correction. The obtained local minima show the dependence between the molecular arrangement of the adsorbates on SWCNT surface and their binding energies. We analyze the interplay between the π-π stacking interactions and isocyanate functional groups. For the analysis of the changes in the electronic structure we calculate the density of states (DOS) and charge density plots.

  6. Increasing the length of single-wall carbon nanotubes in a magnetically enhanced arc discharge

    NASA Astrophysics Data System (ADS)

    Keidar, Michael; Levchenko, Igor; Arbel, Tamir; Alexander, Myriam; Waas, Anthony M.; Ostrikov, Kostya (Ken)

    2008-01-01

    It is demonstrated that a magnetic field has a profound effect on the length of a single-wall carbon nanotube (SWCNT) synthesized in the arc discharge. The average length of SWCNT increases by a factor of 2 in discharge with magnetic field as compared with the discharge without magnetic field, and the yield of long nanotubes with lengths above 5μm also increases. A model of SWCNT growth on metal catalyst in arc plasma was developed. Monte-Carlo simulations confirm that the increase of the plasma density in the magnetic field leads to an increase in the nanotube growth rate and thus leads to longer nanotubes.

  7. Optical heating and temperature determination of core-shell gold nanoparticles and single-walled carbon nanotube microparticles.

    PubMed

    Yashchenok, Alexey; Masic, Admir; Gorin, Dmitry; Inozemtseva, Olga; Shim, Bong Sup; Kotov, Nicholas; Skirtach, Andre; Möhwald, Helmuth

    2015-03-18

    The real-time temperature measurement of nanostructured materials is particularly attractive in view of increasing needs of local temperature probing with high sensitivity and resolution in nanoelectronics, integrated photonics, and biomedicine. Light-induced heating and Raman scattering of single-walled carbon nanotubes with adsorbed gold nanoparticles decorating silica microparticles are reported, by both green and near IR lasers. The plasmonic shell is used as nanoheater, while the single-walled carbon nanotubes are Raman active and serve as a thermometer. Stokes and Anti-Stokes Raman spectra of single-walled carbon nanotubes serve to estimate the effective light-induced temperature rise on the metal nanoparticles. The temperature rise is constant with time, indicating stability of the adsorption density. The effective temperatures derived from Stokes and Anti-Stokes intensities are correlated with those measured in a heating stage. The resolution of the thermal experiments in our study was found to be 5-40 K.

  8. Electromechanical properties of single-walled carbon nanotube devices on micromachined cantilevers

    NASA Astrophysics Data System (ADS)

    Jeon, Eun-Kyoung; Park, Chan-Hyun; Lee, Jung A.; Kim, Min-Seok; Lee, Kwang-Cheol; So, Hye-Mi; Ahn, Chiwon; Chang, Hyunju; Kong, Ki-jeong; Kim, Ju-Jin; Lee, Jeong-O.

    2012-11-01

    We have investigated the electromechanical properties of single-walled carbon nanotubes (SWNTs) by constructing carbon nanotube transistors on micro-cantilevers. SWNTs and ultra-long carbon nanotubes (UNTs) were grown on free-standing Si3N4 membranes by using chemical vapor deposition, and electrical contacts were generated with electron beam lithography and lift-off. The cantilevers bearing SWNT devices were micromachined so that hybrid cantilevers with various spring constants were fabricated. To measure the electromechanical properties of the SWNTs, precisely controlled forces were generated by a microbalance and applied to the hybrid cantilever devices. Upon bending, the conductances of the metallic and large-gap semiconducting UNTs showed no notable change, whereas the conductances of the small-gap semiconducting UNTs and networks of SWNTs increased. Numerical simulations of bended SWNT made using a multiscale simulator supported the hypothesis that the small-gap semiconducting SWNTs undergo a metallic transformation upon bending.

  9. Optical and vibrational properties of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kennedy, W. Joshua

    This work is a study of the optical properties of single-wall carbon nanotubes (SWNTs) using continuous wave (CW) modulation spectroscopy and resonant Raman scattering. SWNTs comprise a nanoscale, quasi-1D system in which the electrons are strongly interacting, resulting in the photo-generation of excitons. Our optical studies have revealed the behavior of these excitons under a number of different perturbations to the system. We have used absorption, reflectance, electro-absorption (EA), photo-induced absorption (PA), charge-induced absorption (CIA), and resonant Raman scattering (RRS) on films of SWNTs. Our EA results provide strong evidence for the dominance of excitons in the optical absorption spectra of SWNT films. The absence of Franz-Keldysh oscillations and the presence of a derivative-like structure of the EA spectra indicate that the oscillator strength goes to the generation of excitons and not to interband electronic transitions. Furthermore, some of the photo-generated excitons are long-lived due to charge trapping in individual tubes within bundles, and this leads to a PA spectrum that is extraordinarily similar to the EA signal. When SWNTs are electrochemically doped we see that the exciton absorption is bleached due to k-space filling and screening of the excitons by the modified local dielectric, while there is very little shift in the exciton transition energies due to band-gap renormalization. Simultaneously the infrared absorption, which is due to Drude free-carriers absorption, is enhanced. A similar behavior is observed in the case of direct charge injection. The RRS of doped SWNT samples shows a frequency shift of many of the Raman-active modes that is commensurate with the macroscopic actuation observed in nanotube-based electrochemical devices. This indicates that doping-induced changes in the lattice are connected with softening and stiffening of the vibrational modes. Our results impact many proposed technologies that exploit the unique

  10. Ultrafast optical spectroscopy of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ostojic, Gordana

    Wavelength-dependent, near-infrared pump-probe study of micelle-suspended Single-Walled Carbon Nanotubes (SWCNTs) whose linear absorption spectra show chirality-assigned peaks is presented. Two distinct relaxation regimes were observed: fast (0.3--1.2 ps) and slow (5--20 ps). The slow component, which has previously been unobserved in pump-probe measurements of bundled tubes, was resonantly enhanced whenever the pump photon energy matched with an interband absorption peak, and it is attributed to interband carrier recombination. It represents the lower limit of the intrinsic radiative recombination time of photoexcited carriers in SWCNTs since the exact value of this parameter depends on the presence of possible nonradiative recombination channels. The slow decay component was highly dependent on the pH of the solution, suggesting that the surrounding H+ ions strongly affect electronic states in nanotubes through the Burnstein-Moss effect. The effect was bandgap energy dependent, affecting the smaller bandgap tubes more significantly. To elucidate carrier dynamics in more detail, nondegenerate pump-probe experiments with wide and continuum probing throughout the lowest and second lowest energy transition ranges of SWCNTs were used. Complex signals were revealed with photoinduced absorption and bleaching, both of which were strongly wavelength dependent. Due to the high optical quality of unbundled SWCNT samples, clear signs of band filling and broadening of the exciton absorption peaks were found to be the main nonlinear mechanisms. The identification of these nonlinear mechanisms presents a novel explanation of the observed nonlinear behavior of nanotubes in general and helps clarify the controversial issues presented in previously published work. This explanation is also consistent with the previously observed pump-probe signals in bundled nanotube samples. Another novel and important conclusion drawn from the nondegenerate pump-probe experiments is that the

  11. Antimicrobial Biomaterials based on Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Aslan, Seyma

    Biomaterials that inactivate bacteria are needed to eliminate medical device infections. We investigate the antimicrobial nature of single-walled carbon nanotubes (SWNT) incorporated within biomedical polymers. In the first part, we focus on SWNT dispersed in the common biomedical polymer poly(lactic-co-glycolic acid) (PLGA) as a potential antimicrobial biomaterial. We find Escherichia coli and Staphylococcus epidermidis viability and metabolic activity to be significantly diminished in the presence of SWNT-PLGA, and to correlate with SWNT length and concentration. Up to 98 % of bacteria die within one hour of SWNT-PLGA versus 15-20% on pure PLGA. Shorter SWNT are found to be more toxic, possibly due to an increased density of open tube ends. In the second part, we investigate the antimicrobial activity of SWNT layer-by-layer (LbL) assembled with the polyelectrolytes poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA). The dispersibility of SWNT in aqueous solution is significantly improved via the biocompatible nonionic surfactant polyoxyethylene(20)sorbitan monolaurate (Tween 20) and the amphiphilic polymer phospholipid-poly(ethylene glycol) (PL-PEG). Absorbance spectroscopy and transmission electron microscopy (TEM) show SWNT with either Tween 20 or PL-PEG in aqueous solution to be well dispersed. Quartz crystal microgravimetry with dissipation (QCMD) measurements show both SWNT-Tween and SWNT-PL-PEG to LbL assemble with PLL and PGA into multilayer films, with the PL-PEG system yielding the greater final SWNT content. Bacterial inactivation rates are significantly higher (up to 90%) upon 24 hour incubation with SWNT containing films, compared to control films (ca. 20%). In the third part, we study the influence of bundling on the LbL assembly of SWNT with charged polymers, and on the antimicrobial properties of the assembled film. QCMD measurements show the bundled SWNT system to adsorb in an unusually strong fashion—to an extent three times greater than that

  12. Single Walled Carbon Nanohorns as Photothermal Cancer Agents

    SciTech Connect

    Whitney, John; Sarkar, Saugata; Zhang, Jianfei; Do, Thao; Manson, Mary kyle; Campbell, Tom; Puretzky, Alexander A; Rouleau, Christopher M; More, Karren Leslie; Geohegan, David B; Rylander, Christopher; Dorn, Harry C; Rylander, Nichole M

    2011-01-01

    Nanoparticles have significant potential as selective photo-absorbing agents for laser based cancer treatment. This study investigates the use of single walled carbon nanohorns (SWNHs) as thermal enhancers when excited by near infrared (NIR) light for tumor cell destruction. Absorption spectra of SWNHs in deionized water at concentrations of 0, 0.01, 0.025, 0.05, 0.085, and 0.1 mg/ml were measured using a spectrophotometer for the wavelength range of 200-1,400 nm. Mass attenuation coefficients were calculated using spectrophotometer transmittance data. Cell culture media containing 0, 0.01, 0.085, and 0.333 mg/ml SWNHs was laser irradiated at 1,064 nm wavelength with an irradiance of 40 W/cm{sup 2} for 0-5 minutes. Temperature elevations of these solutions during laser irradiation were measured with a thermocouple 8 mm away from the incident laser beam. Cell viability of murine kidney cancer cells (RENCA) was measured 24 hours following laser treatment with the previously mentioned laser parameters alone or with SWNHs. Cell viability as a function of radial position was determined qualitatively using trypan blue staining and bright field microscopy for samples exposed to heating durations of 2 and 6 minutes alone or with 0.085 mg/ml SWNHs. A Beckman Coulter Vi-Cell instrument quantified cell viability of samples treated with varying SWNH concentration (0, 0.01, 0.085, and 0.333 mg/ml) and heating durations of 0-6 minutes. Spectrophotometer measurements indicated inclusion of SWNHs increased light absorption and attenuation across all wavelengths. Utilizing SWNHs with laser irradiation increased temperature elevation compared to laser heating alone. Greater absorption and higher temperature elevations were observed with increasing SWNH concentration. No inherent toxicity was observed with SWNH inclusion. A more rapid and substantial viability decline was observed over time in samples exposed to SWNHs with laser treatment compared with samples experiencing laser

  13. Controlling exciton photophysics in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sarpkaya, Ibrahim

    Single-walled carbon nanotubes (SWCNTs) have been studied extensively by scientists and engineers due to their unique mechanical, optical, electronic and thermal properties that make them attractive for both fundamental research and device applications. Specifically, important optical properties of SWCNTs such as formation of strongly bound excitons (electron-hole pairs), being stable at room temperature, and bandgap-tunable light emission from visible to telecom wavelengths make them a promising material for optoelectronic and nanophotonic devices. However, the photophysics of excitons in SWCNTs is not yet fully understood and is largely affected by detrimental extrinsic effects, which give rise to strongly reduced device performance. This dissertation demonstrates novel methods and techniques to better understand and to control the photophysics of excitons in SWCNTs. The first part presents novel ways to completely remove detrimental spectral diffusion and blinking in the optical emission of surfactant dispersed SWCNTs on millisecond time scales and also demonstrates 50-fold enhanced exciton emission. Furthermore, pronounced photon antibunching is observed for the first time under resonant excitation. The demonstrated single photon emission is promising for applications in quantum cryptography, while the achieved stable long term emission is important for optoelectronic devices. The second part demonstrates a new regime of intrinsic exciton photophysics in ultra-clean SWCNTs that is characterized by ultra-narrow exciton linewidth and prolonged emission times up to 18 ns. These lifetimes are two orders of magnitude better than prior measurements and in agreement with values predicted by theorists a decade ago. Moreover, I measure for the first time exciton decoherence times of individual nanotubes in the time-domain and demonstrate fourfold prolonged values up to 2 ps compared to previous ensemble studies. Finally, I demonstrate a novel method which controls

  14. Gel electrophoresis using a selective radical for the separation of single-walled carbon nanotubes.

    PubMed

    Mesgari, Sara; Sundramoorthy, Ashok Kumar; Loo, Leslie S; Chan-Park, Mary B

    2014-01-01

    We have applied agarose gel electrophoresis (AGE) to single-walled carbon nanotubes (SWNTs) that have been pre-reacted with metallic-selective ionic radicals and then re-suspended with sodium cholate (SC) surfactant to obtain highly purified (up to 98%) semiconducting single-walled carbon nanotubes (s-SWNTs). The proposed combination method exploits the preferential reactivity with the metallic nanotube of the radicals generated from an azo naphthalene compound (Direct Blue 71(I)) to preferentially increase the surface charge, and therefore the electrophoretic mobilities, of the metallic nanotube population under the influence of the electric field in AGE. The excellent separation achieved was verified by UV-vis-NIR and Raman spectroscopy as well as by the performance of field effect transistors fabricated with semiconducting-enriched SWNTs. FETs fabricated with -assisted AGE-separated semiconducting nanotubes exhibited mobilities of ∼3.6 to 11.7 cm(2) V(-1) s(-1) and on/off ratios from 10(2) to 10(6).

  15. Single-Wall Carbon Nanotube Production by the Arc Process: A Parametric Study

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Gorelik, Olga; Proft, William J.

    2000-01-01

    Single wall carbon nanotubes are produced using the arc discharge process. Graphite anodes are filled with a mixture of nickel and yttrium metallic powders, then vaporized by creating a high current arc. By varying the current, gap distance, and ambient pressure it is shown that the best yield of single wall carbon nanotubes is obtained within a narrow range of conditions. The relative yield and purity of the product are indicated semi-quantitatively from scanning electric microscopy (SEM) and thermogravimetric analysis (TGA). Two types of anodes have been investigated. The first is hollow and filled with a powder mixture of graphite, nickel and yttrium. The second is filled with a paste made of a mixture of metal nitrates, graphite powder and carbon adhesive, then reduced in an argon atmosphere at high temperature. Product purity and yield will be compared for the two types of anodes. The graphite in the anodes may have hydrogen attached in the pores. To remove this impurity anodes have been baked up to 1400 - 1500 C. The effect of baking the anodes on impurities in the product will be given.

  16. Single-walled carbon nanotube buckypaper and mesophase pitch carbon/carbon composites

    NASA Astrophysics Data System (ADS)

    Park, Jin Gyu; Yun, Nam Gyun; Park, Young Bin; Liang, Richard; Lumata, Lloyd; Brooks, James; Zhang, Chuck; Wang, Ben; High-Performance Materials Institute, Fsu Collaboration; National High Magnetic Field Laboratory, Fsu Collaboration

    2011-03-01

    Carbon/carbon composites consisting of single-walled carbon nanotube (SWCNT) buckypaper (BP) and mesophase pitch resin have been produced through impregnation of BP with pitch using toluene as a solvent. Drying, stabilization and carbonization processes were performed sequentially, and repeated to increase the pitch content. Voids in the carbon/carbon composite samples decreased with increasing impregnation process cycles. Electrical conductivity and density of the composites increased with carbonization by two to three times that of pristine BP. These results indicate that discontinuity and intertube contact barriers of SWCNTs in the BP are partially overcome by the carbonization process of pitch. The temperature dependence of the Raman shift shows that mechanical strain is increased since carbonized pitch matrix surrounds the nanotubes. High-Performance Materials Institute, NSF DMR-0602859, NSF DMR-0654118.

  17. Synthesis of SiC nanorods from sheets of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Muñoz, E.; Dalton, A. B.; Collins, S.; Zakhidov, A. A.; Baughman, R. H.; Zhou, W. L.; He, J.; O'Connor, C. J.; McCarthy, B.; Blau, W. J.

    2002-06-01

    We report the unexpected synthesis of SiC nanorods during thermally annealing single-walled carbon nanotube sheets (SWNTs) at 1000 °C between two silicon wafers. The exterior layers of the carbon nanotube sheets were converted into a network of SiC nanorods, while the carbon nanotubes interior to the sheet remain unchanged. The nanotube sheets that underwent this reaction were comprised of small diameter nanotubes made by a high-pressure carbon monoxide process (HiPco), which contain iron catalyst. Using the same reaction conditions, SiC formation was not observed for sheets of purified, larger diameter nanotubes made by laser ablation, which contained a small amount of residual metal catalysts.

  18. Structural modification of nanoporous carbon with single wall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Yi, Bo

    A novel CC nanocomposite was synthesized by pyrolysis of well dispersed individual functionalized SWNTs in a thermosetting resin, poly(furfuryl alcohol) (PFA). Strong interaction between SWNT and nanoporous carbon derived from PFA (PFA-NPC) was obtained with this strategy and the integrity of SWNTs was maintained after heat treatment. Usually, it is challenging to separate SWNT bundles and disperse them in preparation of composites. 50 wt% SWNT/NPC composites prepared with solution blending showed mass transfer rate of ˜140% higher than the original NPC. The improvement was not significant due to poor dispersion and the bundle structure of SWNTs. Functionalization of SWNTs successfully separated the SWNT bundles and solved the problems of dispersion. In this process, the SWNTs were first functionalized with sulfonic acid groups (SA-SWNT) on sidewall. Then they were converted to PFA-grafted SWNT (PFA-SWNT) by in situ polymerization of furfuryl alcohol (FA). NPC/SWNT nanocomposite was generated by pyrolysis of PFA-SWNT at 600°C. The structural transformation of NPC/SWNT at high temperature was studied by heating it at temperatures from 1200 to 2000°C in vacuum and characterized with HRTEM and Raman spectra. It was found that NPC and SWNT coalesce upon heat treatment and NPC tended to graphitize along the axis of neighboring nanotubes at temperature higher than 1400°C. Complete graphitization of NPC and SWNTs was obtained at 2000°C, when the NPC transformed to graphitic nanoribbons (GNRs) and SWNT or DWNT collapsed within the confines of the GNR. The mass transfer rate in 0.05 wt% SWNT/NPC nanocomposite was ˜2 times higher than that in the pure NPC. Similar improvement required SWNT concentration of ˜60 wt% in the SWNT/NPC composites prepared by solution blending. SWNT/NPC nanocomposite fibers prepared from 0.1 wt% SA-SWNT/FA had ˜13% increase of Young's modulus over the pure NPC fibers when they were pyrolyzed at 400 -- 1600ºC. The augment was slightly

  19. Reaction Of Single-Wall Carbon Nanotubes With Radicals

    NASA Astrophysics Data System (ADS)

    Lobach, A. S.; Solomentsev, V. V.; Obraztsova, E. D.; Shchegolikhin, A. N.; Sokolov, V. I.

    2004-09-01

    A method for functionalizing the sidewalls of HiPco SWNT via interaction with carbon- and metal-centered radicals is presented. A number of methods: UV-vis-NIR spectroscopy, thermogravimetric analysis, TEM and Raman spectroscopy provided a direct evidence of a chemical attachment of functional groups to the tubes. Functionalization was shown to be reversible: a thermal treatment led to the recovering of pristine structure of SWNT.

  20. Single-walled carbon nanotubes as a multimodal — thermoacoustic and photoacoustic — contrast agent

    PubMed Central

    Pramanik, Manojit; Swierczewska, Magdalena; Green, Danielle; Sitharaman, Balaji; Wang, Lihong V.

    2009-01-01

    We have developed a novel carbon nanotube-based contrast agent for both thermoacoustic and photoacoustic tomography. In comparison with de-ionized water, single-walled carbon nanotubes exhibited more than two-fold signal enhancement for thermoacoustic tomography at 3 GHz. In comparison with blood, they exhibited more than six-fold signal enhancement for photoacoustic tomography at 1064 nm wavelength. The large contrast enhancement of single-walled carbon nanotubes was further corroborated by tissue phantom imaging studies. PMID:19566311

  1. Different techniques for characterizing single-walled carbon nanotube purity

    NASA Astrophysics Data System (ADS)

    Yuca, Neslihan; Camtakan, Zeyneb; Karatepe, Nilgün

    2013-09-01

    Transition-metal catalysts, fullerenes, graphitic carbon, amorphous carbon, and graphite flakes are the main impurities in carbon nanotubes. In this study, we demonstrate an easy and optimum method of cleaning SWCNTs and evaluating their purity. The purification method, which employed oxidative heat treatment followed by 6M HNO3, H2SO4, HNO3:H2SO4 and HCl acid reflux for 6h at 120°C and microwave digestion with 1.5M HNO3 for 0.5h at 210°C which was straightforward, inexpensive, and fairly effective. The purified materials were characterized by thermogravimetric analysis and nuclear techniques such as INAA, XRF and XRD.

  2. Ultrashort single-walled carbon nanotubes in a lipid bilayer as a new nanopore sensor

    PubMed Central

    Liu, Lei; Yang, Chun; Zhao, Kai; Li, Jingyuan; Wu, Hai-Chen

    2013-01-01

    An important issue in nanopore sensing is to construct stable and versatile sensors that can discriminate analytes with minute differences. Here we report a means of creating nanopores that comprise ultrashort single-walled carbon nanotubes inserted into a lipid bilayer. We investigate the ion transport and DNA translocation through single-walled carbon nanotube nanopores and find that our results are fundamentally different from previous studies using much longer single-walled carbon nanotubes. Furthermore, we utilize the new single-walled carbon nanotube nanopores to selectively detect modified 5-hydroxymethylcytosine in single-stranded DNA, which may have implications in screening specific genomic DNA sequences. This new nanopore platform can be integrated with many unique properties of carbon nanotubes and might be useful in molecular sensing such as DNA-damage detection, nanopore DNA sequencing and other nanopore-based applications. PMID:24352224

  3. Ultrashort single-walled carbon nanotubes in a lipid bilayer as a new nanopore sensor

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Yang, Chun; Zhao, Kai; Li, Jingyuan; Wu, Hai-Chen

    2013-12-01

    An important issue in nanopore sensing is to construct stable and versatile sensors that can discriminate analytes with minute differences. Here we report a means of creating nanopores that comprise ultrashort single-walled carbon nanotubes inserted into a lipid bilayer. We investigate the ion transport and DNA translocation through single-walled carbon nanotube nanopores and find that our results are fundamentally different from previous studies using much longer single-walled carbon nanotubes. Furthermore, we utilize the new single-walled carbon nanotube nanopores to selectively detect modified 5-hydroxymethylcytosine in single-stranded DNA, which may have implications in screening specific genomic DNA sequences. This new nanopore platform can be integrated with many unique properties of carbon nanotubes and might be useful in molecular sensing such as DNA-damage detection, nanopore DNA sequencing and other nanopore-based applications.

  4. A remote sensor for detecting methane based on palladium-decorated single walled carbon nanotubes.

    PubMed

    Liu, Jian; Li, Guomin

    2013-07-10

    The remote detection of the concentration of methane at room temperature is performed by a sensor that is configured by the combination of radio frequency identification (RFID), and functionalized carbon nanotubes (CNTs). The proposed sensor is schemed as a thin film RFID tag in a polyethylene substrate, on which a metal trace dipole, a metal trace T impedance matching networks, a 0.5 µm-CMOS RF/DC rectifier chipset and a sensor head of palladium-decorated single walled carbon nanotubes (Pd-SWCNTs) are surface mounted in cascade. The performances of the sensor are examined and described by the defined parameters of the received signal strength index (RSSI) and the comparative analog identifier (∆AID). Results validate the sensor's ability to detect molecules of methane at room temperature, showing that the RSSI can increase 4 dB and the ∆AID can increase 3% in response to methane concentrations ranging from zero to 100 ppm.

  5. Toxicity of Raw and Purified Single-Walled Carbon Nanotubes in Rat's Lung Epithelial and Cervical Cancer Cells.

    PubMed

    Goornavar, Virupaxi; Biradar, Santoshkumar; Ezeagwu, Christian; Ezeagwu, Dexter; Hall, Joseph C; Ramesh, Govindarajan T

    2015-03-01

    The increased applications of carbon nanotubes in the field of drug delivery, bioimaging and biosensors demand nanotubes to be of highest purity, free from metallic impurities and amorphous carbon. All of these sectors require a profound investigation about the toxic effects on human and the environment. Many attempts have been made to purify and surface modify the carbon nanotubes, however a detailed study on the raw and purified material has yet to be conducted. Here we present the toxicity studies of raw and the purified single-walled carbon nanotubes in rat's lung epithelial cell and cervical cancer cells (HeLa). These cells were treated with increasing concentration of 0.5 µg/mL to 50 µg/mL and the various biocompatibility assays were performed. The results showed an increased cell death with purified single-walled carbon nanotubes followed by the depletion of antioxidant levels and activation of the caspase cascade at a rapid rate compared to raw single-walled carbon nanotubes. This suggests that purified single walled carbon nanotubes are more toxic to the cells and exhibit ultra-fine particulate matter like toxicity.

  6. Quality of horizontally aligned single-walled carbon nanotubes: Is methane as carbon source better than ethanol?

    NASA Astrophysics Data System (ADS)

    Gao, Fenglei; Zhang, Lijie; Yang, Yun; Huang, Shaoming

    2010-03-01

    Chemical vapor deposition (CVD) growth of horizontally aligned single-walled carbon nanotubes (SWNTs) was studied using two representative carbon source sources: ethanol and methane. The resulting SWNTs were compared for similar reaction conditions which were based on the formation of Ni metal nanoparticles selective electrochemical deposition (SED) on the defect sites of SWNTs. The products were analyzed by Raman spectroscopy and SEM. The results demonstrate that methane was much better carbon source for growing high quality horizontal alignment of SWNTs than ethanol due to the etching effects of OH radicals on the SWNTs.

  7. Controlling the crystalline three-dimensional order in bulk materials by single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    López-Andarias, Javier; López, Juan Luis; Atienza, Carmen; Brunetti, Fulvio G.; Romero-Nieto, Carlos; Guldi, Dirk M.; Martín, Nazario

    2014-04-01

    The construction of ordered single-wall carbon nanotube soft-materials at the nanoscale is currently an important challenge in science. Here we use single-wall carbon nanotubes as a tool to gain control over the crystalline ordering of three-dimensional bulk materials composed of suitably functionalized molecular building blocks. We prepare p-type nanofibres from tripeptide and pentapeptide-containing small molecules, which are covalently connected to both carboxylic and electron-donating 9,10-di(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene termini. Adding small amounts of single-wall carbon nanotubes to the so-prepared p-nanofibres together with the externally controlled self assembly by charge screening by means of Ca2+ results in new and stable single-wall carbon nanotube-based supramolecular gels featuring remarkably long-range internal order.

  8. Binding of hydroxylated single-walled carbon nanotubes to two hemoproteins, hemoglobin and myoglobin.

    PubMed

    Wang, Yan-Qing; Zhang, Hong-Mei; Cao, Jian

    2014-12-01

    Herein, we studied the binding interactions between hydroxylated single-walled carbon nanotubes and hemoglobin and myoglobin by the use of multi-spectral techniques and molecular modeling. The ultraviolet-vis absorbance and circular dichroism spectral results indicated that the binding interactions existed between hydroxylated single-walled carbon nanotubes and hemoglobin/myoglobin. These binding interactions partially affected the soret/heme bands of hemoglobin and myoglobin. The secondary structures of hemoproteins were partially destroyed by hydroxylated single-walled carbon nanotubes. Fluorescence studies suggested that the complexes formed between hydroxylated single-walled carbon nanotubes and hemoglobin/myoglobin by hydrogen bonding, hydrophobic, and π-π stacking interactions. In addition, molecular modeling analysis well supported the experimental results.

  9. Change in the electrical characteristics of single-walled carbon nanotube networks under photoresist treatment

    NASA Astrophysics Data System (ADS)

    Si, Mi-Suk; Kim, Ju-Jin; Choi, Won Jin; Lee, Jeong-O.

    2016-08-01

    The electrical properties of a single-walled carbon nanotube network were investigated after photoresist treatment with the pristine device. Atomic force microscopy found that the diameters of the single-walled carbon nanotubes were increased after photoresist treatment and that the photoresist could not be completely removed from nanotube surfaces by using a simple cleaning process with an organic solvent. Although the presence of a residual photoresist had no noticeable effects on the Raman spectrum of single-walled carbon nanotubes in our devices, the charge carrier mobilities and the on/off ratios of the single-walled carbon nanotube devices were lowered due to the photoresist treatment, and the gate-hysteresis behavior in the devices that had undergone photoresist treatment was found to be different from that of pristine devices.

  10. Photonic density of states in the vicinity of a single-wall finite-length carbon nanotube

    NASA Astrophysics Data System (ADS)

    Nemilentsau, A.; Ya Slepyan, G.; Maksimenko, S. A.

    2009-07-01

    Photonic density of states in the vicinity of a single-wall finite-length carbon nanotube (CNT) is investigated theoretically in this paper. The analysis is based on the fluctuation-dissipative theorem in the Callen-Welton form. The Dyson equation for the Green dyadic of the electromagnetic field in the presence of CNT is formulated and a method for its numerical solution is elaborated. We show that the photonic density of states spectrum has a nontrivial resonant structure in the terahertz range in the vicinity of the metallic single-wall CNT. The origin of these resonances is the surface plasmon resonances on the CNT's edges.

  11. Nanocatalyst shape and composition during nucleation of single-walled carbon nanotubes.

    PubMed

    Gomez-Ballesteros, Jose L; Burgos, Juan C; Lin, Pin Ann; Sharma, Renu; Balbuena, Perla B

    The dynamic evolution of nanocatalyst particle shape and carbon composition during the initial stages of single-walled carbon nanotube growth by chemical vapor deposition synthesis is investigated. Classical reactive and ab initio molecular dynamics simulations are used, along with environmental transmission electron microscope video imaging analyses. A clear migration of carbon is detected from the nanocatalyst/substrate interface, leading to a carbon gradient showing enrichment of the nanocatalyst layers in the immediate vicinity of the contact layer. However, as the metal nanocatalyst particle becomes saturated with carbon, a dynamic equilibrium is established, with carbon precipitating on the surface and nucleating a carbon cap that is the precursor of nanotube growth. A carbon composition profile decreasing towards the nanoparticle top is clearly revealed by the computational and experimental results that show a negligible amount of carbon in the nanoparticle region in contact with the nucleating cap. The carbon composition profile inside the nanoparticle is accompanied by a well-defined shape evolution of the nanocatalyst driven by the various opposing forces acting upon it both from the substrate and from the nascent carbon nanostructure. This new understanding suggests that tuning the nanoparticle/substrate interaction would provide unique ways of controlling the nanotube synthesis.

  12. Nanocatalyst shape and composition during nucleation of single-walled carbon nanotubes

    SciTech Connect

    Gomez-Ballesteros, Jose L.; Burgos, Juan C.; Lin, Pin Ann; Sharma, Renu; Balbuena, Perla B.

    2015-12-07

    The dynamic evolution of nanocatalyst particle shape and carbon composition during the initial stages of single-walled carbon nanotube growth by chemical vapor deposition synthesis is investigated. Classical reactive and ab initio molecular dynamics simulations are used, along with environmental transmission electron microscope video imaging analyses. A clear migration of carbon is detected from the nanocatalyst/substrate interface, leading to a carbon gradient showing enrichment of the nanocatalyst layers in the immediate vicinity of the contact layer. However, as the metal nanocatalyst particle becomes saturated with carbon, a dynamic equilibrium is established, with carbon precipitating on the surface and nucleating a carbon cap that is the precursor of nanotube growth. A carbon composition profile decreasing towards the nanoparticle top is clearly revealed by the computational and experimental results that show a negligible amount of carbon in the nanoparticle region in contact with the nucleating cap. The carbon composition profile inside the nanoparticle is accompanied by a well-defined shape evolution of the nanocatalyst driven by the various opposing forces acting upon it both from the substrate and from the nascent carbon nanostructure. In conclusion, this new understanding suggests that tuning the nanoparticle/substrate interaction would provide unique ways of controlling the nanotube synthesis.

  13. Synthesis and Electronic Transport in Single-Walled Carbon Nanotubes of Known Chirality

    NASA Astrophysics Data System (ADS)

    Caldwell, Robert Victor

    Since their discovery in 1991, carbon nanotubes have proven to be a very interesting material for its physical strength, originating from the pure carbon lattice and strong covalent sp2 orbital bonds, and electronic properties which are derived from the lattice structure lending itself to either a metallic or semiconducting nature among its other properties. Carbon nanotubes have been researched with an eye towards industry applications ranging from use as an alloy in metals and plastics to improve physical strength of the resulting materials to uses in the semiconductor industry as either an interconnect or device layer for computer chips to chemical or biological sensors. This thesis focuses on both the synthesis of individual single-walled carbon nanotubes as well as the electrical properties of those tubes. What makes the work herein different from that of other thesis is that the research has been performed on carbon nanotubes of known chirality. Having first grown carbon nanotubes with a chemical vapor deposition growth in a quartz tube using ethanol vapor as a feedstock to grow long individual single-walled carbon nanotubes on a silicon chip that is also compatible with Rayleigh scattering spectroscopy to identify the chiral indices of the carbon nanotubes in question, those tubes were then transferred with a mechanical transfer process specially designed in our research lab onto a substrate of our choosing before an electrical device was made out of those tubes using standard electron beam lithography. The focus in this thesis is on the work that went into designing and testing this process as well as the initial results of the electronic properties of those carbon nanotubes of known chirality, such as the first known electrical measurements on single individual armchair carbon nanotubes as well as the first known electrical measurements of a single semiconducting carbon nanotube on thin hexagonal boron nitride to study the effects of the surface optical

  14. Nanocatalyst shape and composition during nucleation of single-walled carbon nanotubes

    DOE PAGES

    Gomez-Ballesteros, Jose L.; Burgos, Juan C.; Lin, Pin Ann; ...

    2015-12-07

    The dynamic evolution of nanocatalyst particle shape and carbon composition during the initial stages of single-walled carbon nanotube growth by chemical vapor deposition synthesis is investigated. Classical reactive and ab initio molecular dynamics simulations are used, along with environmental transmission electron microscope video imaging analyses. A clear migration of carbon is detected from the nanocatalyst/substrate interface, leading to a carbon gradient showing enrichment of the nanocatalyst layers in the immediate vicinity of the contact layer. However, as the metal nanocatalyst particle becomes saturated with carbon, a dynamic equilibrium is established, with carbon precipitating on the surface and nucleating a carbonmore » cap that is the precursor of nanotube growth. A carbon composition profile decreasing towards the nanoparticle top is clearly revealed by the computational and experimental results that show a negligible amount of carbon in the nanoparticle region in contact with the nucleating cap. The carbon composition profile inside the nanoparticle is accompanied by a well-defined shape evolution of the nanocatalyst driven by the various opposing forces acting upon it both from the substrate and from the nascent carbon nanostructure. In conclusion, this new understanding suggests that tuning the nanoparticle/substrate interaction would provide unique ways of controlling the nanotube synthesis.« less

  15. Formation of single-walled bimetallic coinage alloy nanotubes in confined carbon nanotubes: molecular dynamics simulations.

    PubMed

    Han, Yang; Zhou, Jian; Dong, Jinming; Yoshiyuki, Kawazoe

    2013-10-28

    The growth of single-walled bimetallic Au-Ag, Au-Cu and Ag-Cu alloy nanotubes (NTs) and nanowires (NWs) in confined carbon nanotubes (CNTs) has been investigated by using the classical molecular dynamics (MD) method. It is found that three kinds of single-walled gold-silver, gold-copper and silver-copper alloy NTs could indeed be formed in confined CNTs at any alloy concentration, whose geometric structures are less sensitive to the alloy concentration. And an extra nearly pure Au (Cu) chain will exist at the center of Au-Ag (Au-Cu and Ag-Cu) NTs when the diameters of the outside CNTs are big enough, thus producing a new type of tube-like alloy NWs. The bonding energy differences between the mono- and hetero-elements of the coinage metal atoms and the quasi-one-dimensional confinement from the CNT play important roles in suppressing effectively the "self-purification" effects, leading to formation of these coinage alloy NTs. In addition, the fluid-solid phase transition temperatures of the bimetallic alloy NTs are found to locate between those of the corresponding pure metal tubes. Finally, the dependences of the radial breathing mode (RBM) frequencies and the tube diameters of the alloy NTs on the alloying concentration were obtained, which will be very helpful for identifying both the alloying concentration and the alloy tube diameters in future experiments.

  16. Size-selected Ni catalyst islands for single-walled carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Rider, Amanda E.; Levchenko, Igor; Chan, Kevin K. F.; Tam, Eugene; Ostrikov, Kostya (Ken)

    2008-12-01

    Many properties of single-walled carbon nanotube (SWCNT) arrays are determined by the size and surface coverage of the metal catalyst islands from which they are nucleated. Methods using thermal fragmentation of continuous metal films frequently fail to produce size-uniform islands. Hybrid numerical simulations are used to propose a new approach to controlled self-assembly of Ni islands of the required size and surface coverage using tailored gas-phase generated nanocluster fluxes and adjusted surface temperatures. It is shown that a maximum surface coverage of 0.359 by 0.96-1.02 nm Ni catalyst islands can be achieved at a low surface temperature of 500 K. Optimized growth of Ni catalyst islands can lead to fabrication of size-uniform SWCNT arrays, suitable for numerous nanoelectronic applications. This approach is deterministic and is applicable to a range of nanoassemblies where high surface coverage and island size uniformity are required.

  17. Fabrication of single-walled carbon-nanotube-based pressure sensors.

    PubMed

    Stampfer, C; Helbling, T; Obergfell, D; Schöberle, B; Tripp, M K; Jungen, A; Roth, S; Bright, V M; Hierold, C

    2006-02-01

    We report on the fabrication and characterization of bulk micromachined pressure sensors based on individual single-walled carbon nanotubes (SWNTs) as the active electromechanical transducer elements. The electromechanical sensor device consists of an individual electrically connected SWNT adsorbed on top of a 100-nm-thick atomic layer deposited (ALD) circular alumina (Al(2)O(3)) membrane with a radius in the range of 50-100 microm. A white light interferometer (WLI) was used to measure the deflection of the membrane due to differential pressure, and the mechanical properties of the device were characterized by bulge testing. Finally, we performed the first electromechanical measurements on strained metallic SWNTs adhering to a membrane and found a piezoresistive gauge factor of approximately 210 for metallic SWNTs.

  18. Separation of surfactant functionalized single-walled carbon nanotubes via free solution electrophoresis method

    NASA Astrophysics Data System (ADS)

    Scheibe, Blazej; Rümmeli, Mark; Borowiak-Palen, Ewa; Kalenczuk, Ryszard

    2011-04-01

    This work presents the application of the free solution electrophoresis method (FSE) in the metallic / semiconductive (M/S) separation process of the surfactant functionalized single-walled carbon nanotubes (SWCNTs). The SWCNTs synthesized via laser ablation were purified through high vacuum annealing and subsequent refluxing processes in aqua regia solution. The purified and annealed material was divided into six batches. First three batches were dispersed in anionic surfactants: sodium dodecyl sulfate (SDS), sodium cholate (SC) and sodium deoxycholate (DOC). The next three batches were dispersed in cationic surfactants: cetrimonium bromide (CTAB), benzalkonium chloride (BKC) and cetylpyridinium chloride (CPC). All the prepared SWCNTs samples were subjected to FSE separation process. The fractionated samples were recovered from control and electrode areas and annealed in order to remove the adsorbed surfactants on carbon nanotubes (CNTs) surface. The changes of the van Hove singularities (vHS) present in SWCNTs spectra were investigated via UV-Vis-NIR optical absorption spectroscopy (OAS).

  19. Oxidative enzymatic response of white-rot fungi to single-walled carbon nanotubes.

    PubMed

    Berry, Timothy D; Filley, Timothy R; Blanchette, Robert A

    2014-10-01

    Although carbon nanomaterials such as single-walled carbon nanotubes (SWCNT) are becoming increasingly prevalent in manufacturing, there is little knowledge on the environmental fate of these materials. Environmental degradation of SWCNT is hindered by their highly condensed aromatic structure as well as the size and aspect ratio, which prevents intracellular degradation and limits microbial decomposition to extracellular processes such as those catalyzed by oxidative enzymes. This study investigates the peroxidase and laccase enzymatic response of the saprotrophic white-rot fungi Trametes versicolor and Phlebia tremellosa when exposed to SWCNTs of different purity and surface chemistry under different growth conditions. Both unpurified, metal catalyst-rich SWCNT and purified, carboxylated SWCNTs promoted significant changes in the oxidative enzyme activity of the fungi while pristine SWCNT did not. These results suggest that functionalization of purified SWCNT is essential to up regulate enzymes that may be capable of decomposing CNT in the environment.

  20. Intercalation of heavy alkali metals (K, Rb and Cs) in the bundles of single wall nanotubes

    NASA Astrophysics Data System (ADS)

    Duclaux, L.; Méténier, K.; Lauginie, P.; Salvetat, J. P.; Bonnamy, S.; Beguin, F.

    2000-11-01

    The electric-arc discharge carbon deposits (collaret) containing Single Wall Carbon Nanotubes (SWNTs) were heat treated at 1600 °C during 2 days under N2 flow in order to eliminate the Ni catalyst by sublimation, without modifications of the SWNTs ropes. Sorting this deposit by gravity enabled to obtain in the coarsest particles higher amount of SWNTs ropes than in other particle sizes. The coarser particles of the carbon deposits were reacted with the alkali metals vapor giving intercalated samples with a MC8 composition. The intercalation led to an expansion of the 2D lattice of the SWNTs so that the alkali metals were intercalated in between the tubes within the bundles. Disordered lattices were observed after intercalation of Rb and Cs. The simulations of the X-ray diffractograms of SWNTs reacted with K, gave the best fit for three K ions occupying the inter-tubes triangular cavities. The investigations by EPR, and 13C NMR, showed that doped carbon deposits are metallic.

  1. Carbon nanotubes based transistors composed of single-walled carbon nanotubes mats as gas sensors: A review

    NASA Astrophysics Data System (ADS)

    Bondavalli, Paolo

    2010-06-01

    This contribution presents the main studies on the CNTFET based gas sensors obtained using Single-Walled Carbon Nanotubes mats (SWCNTs) as channel. Although these devices have allowed one to achieve sensors with an impressive sensitivity compared to existing technologies, the physical interpretation of the effect of interaction between the gas molecules and the CNTFETs has not yet been clarified. Concerning selectivity, we will deal with the main routes that have been proposed to overcome this problem: functionalization using polymers, electrodes metal diversification, metal decoration of SWCNT mats.

  2. Single walled carbon nanotube network—Tetrahedral amorphous carbon composite film

    SciTech Connect

    Iyer, Ajai Liu, Xuwen; Koskinen, Jari; Kaskela, Antti; Kauppinen, Esko I.; Johansson, Leena-Sisko

    2015-06-14

    Single walled carbon nanotube network (SWCNTN) was coated by tetrahedral amorphous carbon (ta-C) using a pulsed Filtered Cathodic Vacuum Arc system to form a SWCNTN—ta-C composite film. The effects of SWCNTN areal coverage density and ta-C coating thickness on the composite film properties were investigated. X-Ray photoelectron spectroscopy measurements prove the presence of high quality sp{sup 3} bonded ta-C coating on the SWCNTN. Raman spectroscopy suggests that the single wall carbon nanotubes (SWCNTs) forming the network survived encapsulation in the ta-C coating. Nano-mechanical testing suggests that the ta-C coated SWCNTN has superior wear performance compared to uncoated SWCNTN.

  3. Collision-induced fusion of two single-walled carbon nanotubes: A quantitative study

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Mao, Fei; Meng, Xiang-Rui; Wang, Dong-Qi; Zhang, Feng-Shou

    2016-07-01

    The coalescence processes of two (6, 0) single-walled carbon nanotubes are investigated via coaxial collision based on the self-consistent-charge density-functional tight-binding molecular dynamics method. According to the structure characteristics of the nanotubes, five impact cases are studied to explore the coalescence processes of the nanotubes. The simulation shows that various kinds of carbon nanomaterials, such as graphene sheets, graphene nanoribbons, and single-walled carbon nanotubes with larger diameters, are created after collision. Moreover, some defects formed in the carbon nanomaterials can be eliminated, and even the final configurations which are originally fragmented can almost become intact structures by properly quenching and annealing.

  4. Continuous growth of single-wall carbon nanotubes using chemical vapor deposition

    DOEpatents

    Grigorian, Leonid; Hornyak, Louis; Dillon, Anne C; Heben, Michael J

    2008-10-07

    The invention relates to a chemical vapor deposition process for the continuous growth of a carbon single-wall nanotube where a carbon-containing gas composition is contacted with a porous membrane and decomposed in the presence of a catalyst to grow single-wall carbon nanotube material. A pressure differential exists across the porous membrane such that the pressure on one side of the membrane is less than that on the other side of the membrane. The single-wall carbon nanotube growth may occur predominately on the low-pressure side of the membrane or, in a different embodiment of the invention, may occur predominately in between the catalyst and the membrane. The invention also relates to an apparatus used with the carbon vapor deposition process.

  5. Continuous growth of single-wall carbon nanotubes using chemical vapor deposition

    DOEpatents

    Grigorian, Leonid; Hornyak, Louis; Dillon, Anne C; Heben, Michael J

    2014-09-23

    The invention relates to a chemical vapor deposition process for the continuous growth of a carbon single-wall nanotube where a carbon-containing gas composition is contacted with a porous membrane and decomposed in the presence of a catalyst to grow single-wall carbon nanotube material. A pressure differential exists across the porous membrane such that the pressure on one side of the membrane is less than that on the other side of the membrane. The single-wall carbon nanotube growth may occur predominately on the low-pressure side of the membrane or, in a different embodiment of the invention, may occur predominately in between the catalyst and the membrane. The invention also relates to an apparatus used with the carbon vapor deposition process.

  6. Single-walled carbon nanotube incorporated novel three phase carbon/epoxy composite with enhanced properties.

    PubMed

    Rana, Sohel; Alagirusamy, Ramasamy; Joshi, Mangala

    2011-08-01

    In the present work, single-walled carbon nanotubes were dispersed within the matrix of carbon fabric reinforced epoxy composites in order to develop novel three phase carbon/epoxy/single-walled carbon nanotube composites. A combination of ultrasonication and high speed mechanical stirring at 2000 rpm was used to uniformly disperse carbon nanotubes in the epoxy resin. The state of carbon nanotube dispersion in the epoxy resin and within the nanocomposites was characterized with the help of optical microscopy and atomic force microscopy. Pure carbon/epoxy and three phase composites were characterized for mechanical properties (tensile and compressive) as well as for thermal and electrical conductivity. Fracture surfaces of composites after tensile test were also studied in order to investigate the effect of dispersed carbon nanotubes on the failure behavior of composites. Dispersion of only 0.1 wt% nanotubes in the matrix led to improvements of 95% in Young's modulus, 31% in tensile strength, 76% in compressive modulus and 41% in compressive strength of carbon/epoxy composites. In addition to that, electrical and thermal conductivity also improved significantly with addition of carbon nanotubes.

  7. Spin-orbit coupling and the static polarizability of single-wall carbon nanotubes

    SciTech Connect

    Diniz, Ginetom S. Ulloa, Sergio E.

    2014-07-14

    We calculate the static longitudinal polarizability of single-wall carbon tubes in the long wavelength limit taking into account spin-orbit effects. We use a four-orbital orthogonal tight-binding formalism to describe the electronic states and the random phase approximation to calculate the dielectric function. We study the role of both the Rashba as well as the intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e., when the probing electric field is parallel to the nanotube axis. The spin-orbit interaction modifies the nanotube electronic band dispersions, which may especially result in a small gap opening in otherwise metallic tubes. The bandgap size and state features, the result of competition between Rashba and intrinsic spin-orbit interactions, result in drastic changes in the longitudinal static polarizability of the system. We discuss results for different nanotube types and the dependence on nanotube radius and spin-orbit couplings.

  8. Recent Progress in Obtaining Semiconducting Single-Walled Carbon Nanotubes for Transistor Applications.

    PubMed

    Islam, Ahmad E; Rogers, John A; Alam, Muhammad A

    2015-12-22

    High purity semiconducting single-walled carbon nanotubes (s-SWCNTs) with a narrow diameter distribution are required for high-performance transistors. Achieving this goal is extremely challenging because the as-grown material contains mixtures of s-SWCNTs and metallic- (m-) SWCNTs with wide diameter distributions, typically inadequate for integrated circuits. Since 2000, numerous ex situ methods have been proposed to improve the purity of the s-SWCNTs. The majority of these techniques fail to maintain the quality and integrity of the s-SWCNTs with a few notable exceptions. Here, the progress in realizing high purity s-SWCNTs in as-grown and post-processed materials is highlighted. A comparison of transistor parameters (such as on/off ratio and field-effect mobility) obtained from test structures establishes the effectiveness of various methods and suggests opportunities for future improvements.

  9. Three-dimensional polymeric structures of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lian, Chao-Sheng; Wang, Jian-Tao

    2014-05-01

    We explore by ab initio calculations the possible crystalline phases of polymerized single-wall carbon nanotubes (P-SWNTs) and determine their structural, elastic, and electronic properties. Based on direct cross-linking and intertube sliding-assisted cross-linking mechanisms, we have identified a series of stable three-dimensional polymeric structures for the zigzag nanotubes up to (10,0). Among proposed P-SWNT phases, the structures with favorable diamond-like sp3 intertube bonding configuration and small tube cross-section distortion are found to be the most energetically stable ones. These polymeric crystalline phases exhibit high bulk and shear moduli superior to SWNT bundles, and show metallic or semiconducting properties depending on the diameter of constituent tubes. We also propose by hydrostatic pressure simulations that the intertube sliding between van der Waals bonded nanotubes may be an effective route to promote the polymerization of SWNTs under pressure.

  10. Three-dimensional polymeric structures of single-wall carbon nanotubes.

    PubMed

    Lian, Chao-Sheng; Wang, Jian-Tao

    2014-05-28

    We explore by ab initio calculations the possible crystalline phases of polymerized single-wall carbon nanotubes (P-SWNTs) and determine their structural, elastic, and electronic properties. Based on direct cross-linking and intertube sliding-assisted cross-linking mechanisms, we have identified a series of stable three-dimensional polymeric structures for the zigzag nanotubes up to (10,0). Among proposed P-SWNT phases, the structures with favorable diamond-like sp(3) intertube bonding configuration and small tube cross-section distortion are found to be the most energetically stable ones. These polymeric crystalline phases exhibit high bulk and shear moduli superior to SWNT bundles, and show metallic or semiconducting properties depending on the diameter of constituent tubes. We also propose by hydrostatic pressure simulations that the intertube sliding between van der Waals bonded nanotubes may be an effective route to promote the polymerization of SWNTs under pressure.

  11. Three-dimensional polymeric structures of single-wall carbon nanotubes

    SciTech Connect

    Lian, Chao-Sheng; Wang, Jian-Tao

    2014-05-28

    We explore by ab initio calculations the possible crystalline phases of polymerized single-wall carbon nanotubes (P-SWNTs) and determine their structural, elastic, and electronic properties. Based on direct cross-linking and intertube sliding-assisted cross-linking mechanisms, we have identified a series of stable three-dimensional polymeric structures for the zigzag nanotubes up to (10,0). Among proposed P-SWNT phases, the structures with favorable diamond-like sp{sup 3} intertube bonding configuration and small tube cross-section distortion are found to be the most energetically stable ones. These polymeric crystalline phases exhibit high bulk and shear moduli superior to SWNT bundles, and show metallic or semiconducting properties depending on the diameter of constituent tubes. We also propose by hydrostatic pressure simulations that the intertube sliding between van der Waals bonded nanotubes may be an effective route to promote the polymerization of SWNTs under pressure.

  12. X-ray Absorption Improvement of Single Wall Carbon Nanotube through Gadolinium Encapsulation

    NASA Astrophysics Data System (ADS)

    Alimin; Narsito, I.; Kartini; Santosa, S. J.

    2016-02-01

    X-ray absorption improvement of single-wall carbon nanotube (SWCNT) through gadolinium (Gd) encapsulation has been studied. The liquid phase adsorption using ethanol has been performed for the doping treatment. The Gd-doped SWCNT (Gd@SWCNT) was characterized by nitrogen adsorption isotherms, Raman spectroscopy, Transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA) techniques. A relatively high residual weight of Gd@SWCNT compared to non-doped SWCNT (n-SWCNT) indicated that Gd has been doped in the nanotube. Even though Gd nanoparticles could not be observed clearly by TEM image, however, a significant decrease of nitrogen uptakes at low pressure and RBM (Radial Breathing Mode) upshift of Raman spectra of Gd@SWCNT specimen suggest that the metal nanoparticles might be encapsulated in the internal tube spaces of the nanotube. It was found that Gd-doped in the SWCNT increased significantly mass attenuation coefficient of the nanotube.

  13. Highly efficient exfoliation of individual single-walled carbon nanotubes by biocompatible phenoxylated dextran.

    PubMed

    Kwon, Taeyun; Lee, Gyudo; Choi, Hyerim; Strano, Michael S; Kim, Woo-Jae

    2013-08-07

    Highly efficient exfoliation of individual single-walled carbon nanotubes (SWNTs) was successfully demonstrated by utilizing biocompatible phenoxylated dextran, a kind of polysaccharide, as a SWNT dispersion agent. Phenoxylated dextran shows greater ability in producing individual SWNTs from raw materials than any other dispersing agent, including anionic surfactants and another polysaccharide. Furthermore, with this novel polymer, SWNT bundles or impurities present in raw materials are removed under much milder processing conditions compared to those of ultra-centrifugation procedures. There exists an optimal composition of phenoxy groups (∼13.6 wt%) that leads to the production of high-quality SWNT suspensions, as confirmed by UV-vis-nIR absorption and nIR fluorescence spectroscopy. Furthermore, phenoxylated dextran strongly adsorbs onto SWNTs, enabling SWNT fluorescence even in solid-state films in which metallic SWNTs co-exist. By bypassing ultra-centrifugation, this low-energy dispersion scheme can potentially be scaled up to industrial production levels.

  14. Computational modeling of the thermal conductivity of single-walled carbon nanotube-polymer composites.

    PubMed

    Duong, Hai M; Papavassiliou, Dimitrios V; Mullen, Kieran J; Maruyama, Shigeo

    2008-02-13

    A computational model was developed to study the thermal conductivity of single-walled carbon nanotube (SWNT)-polymer composites. A random walk simulation was used to model the effect of interfacial resistance on the heat flow in different orientations of SWNTs dispersed in the polymers. The simulation is a modification of a previous model taking into account the numerically determined thermal equilibrium factor between the SWNTs and the composite matrix material. The simulation results agreed well with reported experimental data for epoxy and polymethyl methacrylate (PMMA) composites. The effects of the SWNT orientation, weight fraction and thermal boundary resistance on the effective conductivity of composites were quantified. The present model is a useful tool for the prediction of the thermal conductivity within a wide range of volume fractions of the SWNTs, so long as the SWNTs are not in contact with each other. The developed model can be applied to other polymers and solid materials, possibly even metals.

  15. Energy loss of the electron system in individual single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Santavicca, Daniel; Chudow, Joel; Prober, Daniel; Purewal, Meninder; Kim, Philip

    2011-03-01

    We characterize the energy loss of the non-equilibrium electron system in individual metallic single-walled carbon nanotubes at low temperature. Using Johnson noise thermometry, we demonstrate that, for a nanotube with ohmic contacts, the dc resistance at finite bias current directly reflects the average electron temperature. This enables a straightforward determination of the thermal conductance associated with cooling of the nanotube electron system. In analyzing the temperature- and length-dependence of the thermal conductance, we consider contributions from acoustic phonon emission, optical phonon emission, and hot electron outdiffusion. In the same sample, we also characterize the radio frequency heterodyne response. Distinct responses are seen from bolometric detection and from the electrical nonlinearity due to non-ohmic contacts. This work was supported by NSF-DMR and NSF-CHE.

  16. Quantitative thermal imaging of single-walled carbon nanotube devices by scanning Joule expansion microscopy.

    PubMed

    Xie, Xu; Grosse, Kyle L; Song, Jizhou; Lu, Chaofeng; Dunham, Simon; Du, Frank; Islam, Ahmad E; Li, Yuhang; Zhang, Yihui; Pop, Eric; Huang, Yonggang; King, William P; Rogers, John A

    2012-11-27

    Electrical generation of heat in single-walled carbon nanotubes (SWNTs) and subsequent thermal transport into the surroundings can critically affect the design, operation, and reliability of electronic and optoelectronic devices based on these materials. Here we investigate such heat generation and transport characteristics in perfectly aligned, horizontal arrays of SWNTs integrated into transistor structures. We present quantitative assessments of local thermometry at individual SWNTs in these arrays, evaluated using scanning Joule expansion microscopy. Measurements at different applied voltages reveal electronic behaviors, including metallic and semiconducting responses, spatial variations in diameter or chirality, and localized defect sites. Analytical models, validated by measurements performed on different device structures at various conditions, enable accurate, quantitative extraction of temperature distributions at the level of individual SWNTs. Using current equipment, the spatial resolution and temperature precision are as good as ∼100 nm and ∼0.7 K, respectively.

  17. Heteroepitaxial Growth of Single-Walled Carbon Nanotubes from Boron Nitride

    PubMed Central

    Tang, Dai-Ming; Zhang, Li-Li; Liu, Chang; Yin, Li-Chang; Hou, Peng-Xiang; Jiang, Hua; Zhu, Zhen; Li, Feng; Liu, Bilu; Kauppinen, Esko I.; Cheng, Hui-Ming

    2012-01-01

    The growth of single-walled carbon nanotubes (SWCNTs) with predefined structure is of great importance for both fundamental research and their practical applications. Traditionally, SWCNTs are grown from a metal catalyst with a vapor-liquid-solid mechanism, where the catalyst is in liquid state with fluctuating structures, and it is intrinsically unfavorable for the structure control of SWCNTs. Here we report the heteroepitaxial growth of SWCNTs from a platelet boron nitride nanofiber (BNNF), which is composed of stacked (002) planes and is stable at high temperatures. SWCNTs are found to grow epitaxially from the open (002) edges of the BNNFs, and the diameters of the SWCNTs are multiples of the BN (002) interplanar distance. In situ transmission electron microscopy observations coupled with first principles calculations reveal that the growth of SWCNTs from the BNNFs follows a vapor-solid-solid mechanism. Our work opens opportunities for the control over the structure of SWCNTs by hetero-crystallographic epitaxy. PMID:23240076

  18. Systematic Conversion of Single Walled Carbon Nanotubes into n-type Thermoelectric Materials by Molecular Dopants

    PubMed Central

    Nonoguchi, Yoshiyuki; Ohashi, Kenji; Kanazawa, Rui; Ashiba, Koji; Hata, Kenji; Nakagawa, Tetsuya; Adachi, Chihaya; Tanase, Tomoaki; Kawai, Tsuyoshi

    2013-01-01

    Thermoelectrics is a challenging issue for modern and future energy conversion and recovery technology. Carbon nanotubes are promising active thermoelectic materials owing to their narrow bandgap energy and high charge carrier mobility, and they can be integrated into flexible thermoelectrics that can recover any waste heat. We here report air-stable n-type single walled carbon nanotubes with a variety of weak electron donors in the range of HOMO level between ca. −4.4 eV and ca. −5.6 eV, in which partial uphill electron injection from the dopant to the conduction band of single walled carbon nanotubes is dominant. We display flexible films of the doped single walled carbon nanotubes possessing significantly large thermoelectric effect, which is applicable to flexible ambient thermoelectric modules. PMID:24276090

  19. Systematic Conversion of Single Walled Carbon Nanotubes into n-type Thermoelectric Materials by Molecular Dopants

    NASA Astrophysics Data System (ADS)

    Nonoguchi, Yoshiyuki; Ohashi, Kenji; Kanazawa, Rui; Ashiba, Koji; Hata, Kenji; Nakagawa, Tetsuya; Adachi, Chihaya; Tanase, Tomoaki; Kawai, Tsuyoshi

    2013-11-01

    Thermoelectrics is a challenging issue for modern and future energy conversion and recovery technology. Carbon nanotubes are promising active thermoelectic materials owing to their narrow bandgap energy and high charge carrier mobility, and they can be integrated into flexible thermoelectrics that can recover any waste heat. We here report air-stable n-type single walled carbon nanotubes with a variety of weak electron donors in the range of HOMO level between ca. -4.4 eV and ca. -5.6 eV, in which partial uphill electron injection from the dopant to the conduction band of single walled carbon nanotubes is dominant. We display flexible films of the doped single walled carbon nanotubes possessing significantly large thermoelectric effect, which is applicable to flexible ambient thermoelectric modules.

  20. Heat-induced transformations in coronene-single-walled carbon nanotube systems

    NASA Astrophysics Data System (ADS)

    Chernov, Alexander I.; Fedotov, Pavel V.; Krylov, Alexander S.; Vtyurin, Alexander N.; Obraztsova, Elena D.

    2016-03-01

    Coronene molecules are used as filler for single-walled carbon nanotubes. Variation of the synthesis temperature regimes leads to formation of different types of carbon nanostructures inside the nanotubes. Accurate determination of the structures by optical spectroscopy methods remains an important issue in composite materials. Clear distinction between adsorbed organic molecules on the surface of the tubes and filled structures may be accessed by Raman and photoluminescence spectroscopies. We perform additional heat treatment after the initial synthesis procedure and show the evolution of the optical spectral features corresponding to the filled structures and adsorbed materials on the surface of single-walled carbon nanotubes.

  1. Electron spectrum of a single-wall carbon nanotube in the framework of the nonlinear Schrödinger equation

    SciTech Connect

    Ishkhanyan, H. A.; Krainov, V. P.

    2015-08-15

    The electron spectrum of a single-wall carbon metal nanotube is analyzed numerically. The interaction of a free electron with atomic ions and bound electrons is approximated by an attractive delta-function potential in the single-particle Schrödinger equation. The interaction of an electron with other free electrons is presented by the Hartree nonlinear repulsive short-range potential.

  2. Shape transition of unstrained flattest single-walled carbon nanotubes under pressure

    SciTech Connect

    Mu, Weihua E-mail: muwh@itp.ac.cn; Cao, Jianshu; Ou-Yang, Zhong-can

    2014-01-28

    Single walled carbon nanotube's (SWCNT's) cross section can be flattened under hydrostatic pressure. One example is the cross section of a single walled carbon nanotube successively deforms from the original round shape to oval shape, then to peanut-like shape. At the transition point of reversible deformation between convex shape and concave shape, the side wall of nanotube is flattest. This flattest tube has many attractive properties. In the present work, an approximate approach is developed to determine the equilibrium shape of this unstrained flattest tube and the curvature distribution of this tube. Our results are in good agreement with recent numerical results, and can be applied to the study of pressure controlled electric properties of single walled carbon nanotubes. The present method can also be used to study other deformed inorganic and organic tube-like structures.

  3. Catalytic effect of different forms of iron in purification of single-walled carbon nanotubes.

    PubMed

    Suzuki, Tomoko; Inoue, Sakae; Ando, Yoshinori

    2010-06-01

    In the arc plasma jet (APJ) method, a large amount of soot including single wall carbon nanotubes (SWNTs) can be produced in a short time. However, as-grown soot contains a lot of impurities, such as metallic particles used as catalyst and amorphous carbon. Hence it is necessary to purify the soot to obtain pure SWNTs. The biggest problem in purifying APJ-SWNTs is how to remove the thick amorphous carbon covering the catalyst metal particles. By refluxing APJ-SWNTs in hydrogen peroxide using iron particle as catalyst, it can be purified. The added fine particle of pure iron is found to be effective. Then, we examine whether SWNTs can be purified more effectively by adding solution containing the Fe ion instead of the iron particle. We used iron (III) nitrate nonahydrate, hydrogen peroxide decomposing agent which contains catalase and ammonium iron (II) sulfate hexahydrate. In the case of iron (III) nitrate and catalase, purification effect is not obvious. Under these conditions hydrogen peroxide was decomposed into H2O and O2, and the hydroxyl radical was not generated. On the other hand, ammonium iron (II) sulfate is effective. Because of existence of Fe2+ in solution Fenton's reaction takes place. Reaction rate is increased at high temperature. Therefore, APJ-SWNT is purified more effectively if refluxed in hydrogen peroxide using ammonium iron (II) sulfate as catalyst.

  4. NASA-JSC Protocol for the Characterization of Single Wall Carbon Nanotube Material Quality

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram; Nikolaev, Pasha; Gorelik, Olga; Hadjiev, Victor; Holmes, William; Devivar, Rodrigo; Files, Bradley; Yowell, Leonard

    2010-01-01

    It is well known that the raw as well as purified single wall carbon nanotube (SWCNT) material always contain certain amount of impurities of varying composition (mostly metal catalyst and non-tubular carbon). Particular purification method also creates defects and/or functional groups in the SWCNT material and therefore affects the its dispersability in solvents (important to subsequent application development). A number of analytical characterization tools have been used successfully in the past years to assess various properties of nanotube materials, but lack of standards makes it difficult to compare these measurements across the board. In this work we report the protocol developed at NASA-JSC which standardizes measurements using TEM, SEM, TGA, Raman and UV-Vis-NIR absorption techniques. Numerical measures are established for parameters such as metal content, homogeneity, thermal stability and dispersability, to allow easy comparison of SWCNT materials. We will also report on the recent progress in quantitative measurement of non-tubular carbon impurities and a possible purity standard for SWCNT materials.

  5. Chemical approaches towards single-species single-walled carbon nanotubes.

    PubMed

    Liu, Cai-Hong; Zhang, Hao-Li

    2010-10-01

    Small variations in diameter and chirality could bring striking changes in the electronic and optical properties of single-walled carbon nanotubes (SWCNTs). Therefore, SWCNTs of a specific diameter/chirality are required for many applications. In this review we provide an overview of the recent progress in various chemical approaches towards producing specific nanotubes. Issues regarding the structure of SWCNTs, characterization tools and various separation techniques are presented in this article. The benefits and limits of current chemical approaches are discussed and the perspectives of emerging strategies for achieving identical single-walled carbon nanotubes are highlighted.

  6. Optical signatures of the Aharonov-Bohm phase in single-walled carbon nanotubes.

    PubMed

    Zaric, Sasa; Ostojic, Gordana N; Kono, Junichiro; Shaver, Jonah; Moore, Valerie C; Strano, Michael S; Hauge, Robert H; Smalley, Richard E; Wei, Xing

    2004-05-21

    We report interband magneto-optical spectra for single-walled carbon nanotubes in high magnetic fields up to 45 tesla, confirming theoretical predictions that the band structure of a single-walled carbon nanotube is dependent on the magnetic flux phi threading the tube. We have observed field-induced optical anisotropy as well as red shifts and splittings of absorption and photoluminescence peaks. The amounts of shifts and splittings depend on the value of phi/phi(0) and are quantitatively consistent with theories based on the Aharonov-Bohm effect. These results represent evidence of the influence of the Aharonov-Bohm phase on the band gap of a solid.

  7. Vertical Alignment of Single-Walled Carbon Nanotubes on Nanostructure Fabricated by Atomic Force Microscope

    DTIC Science & Technology

    2009-12-16

    Kobayashi Y, Yamashita T, Ueno Y, Niwa O, Homma Y, Ogino T. Extremely intense Raman signals from single-walled carbon nanotubes suspended between Si...carbon nanotube field effect transistors with carbon nanotube electrodes. Appl Phys Lett. 2008;92(4):043110-3. [13] Jung YJ, Homma Y, Ogino T...Homma Y, Yamashita T, Kobayashi Y, Ogino T. Interconnection of nanostructures using carbon nanotubes. Physica B. 2002;323(1-4):122-3. [23] Searson

  8. A Comparison of Single-Wall Carbon Nanotube Electrochemical Capacitor Electrode Fabrication Methods

    DTIC Science & Technology

    2012-01-24

    REPORT A comparison of single-wall carbon nanotube electrochemical capacitor electrode fabrication methods 14. ABSTRACT 16. SECURITY CLASSIFICATION OF... Carbon nanotubes (CNTs) are being widely investigated as a replacement for activated carbon in super- capacitors. A wide range of CNT specific...ORGANIZATION NAMES AND ADDRESSES U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Carbon nanotube

  9. Molecular Dynamics Simulations of the Thermal Conductivity of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Osman, M.; Srivastava, Deepak; Govindan,T. R. (Technical Monitor)

    2000-01-01

    Carbon nanotubes (CNT) have very attractive electronic, mechanical. and thermal properties. Recently, measurements of thermal conductivity in single wall CNT mats showed estimated thermal conductivity magnitudes ranging from 17.5 to 58 W/cm-K at room temperature. which are better than bulk graphite. The cylinderical symmetry of CNT leads to large thermal conductivity along the tube axis, additionally, unlike graphite. CNTs can be made into ropes that can be used as heat conducting pipes for nanoscale applications. The thermal conductivity of several single wall carbon nanotubes has been calculated over temperature range from l00 K to 600 K using non-equilibrium molecular dynamics using Tersoff-Brenner potential for C-C interactions. Thermal conductivity of single wall CNTs shows a peaking behavior as a function of temperature. Dependence of the peak position on the chirality and radius of the tube will be discussed and explained in this presentation.

  10. Optical and mechanical properties of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Marcus, Matthew S.

    The experiments presented in this thesis provide insight into the optical and mechanical properties of carbon nanotubes. In the process of studying the properties of carbon nanotube structures we also discovered some interesting features of intermittent contact atomic force microscopy. Phase data from non-contact AFM reveals in-plane material properties . In the process of characterizing carbon nanotubes with an intermittent contact AFM (ICAFM), we discovered something quite interesting: ICAFM is sensitive to in-plane properties. We found that phase contrast in ICAFM reveals in-plane mechanical properties of the poly-di-acetylene films. Our measurements are possible because, during ICAFM, the cantilever tip oscillates not just perpendicular but also parallel to the sample surface along the long axis of the cantilever. Understanding photo-induced conductivity changes in carbon nanotubes . The basic process for using a nanotube as a photo-detector involves using light to change the conductivity of the nanotube, typically measured as a change in current. We review the different mechanisms for how light changes the conductivity of a nanotube, and then focus on a photo-gating mechanism. In a photo-gating mechanism, light interacts with the nanotube's environment changing the conductivity of the nanotube. Thermally driven oscillations play a significant role in chemical vapor deposition growth. The elevated temperatures during the CVD growth thermally drive nanotube oscillations with amplitudes on the order of 80nm. Nanotubes suspended a small distance above the substrate will often oscillate with an amplitude as large as the suspension height and interact with the substrate. The large binding energy between the nanotube and the substrate causes the nanotube to become stuck: the nanotube is no longer suspended. Using data from CVD growths on our suspended structures we are able to extract a Young's modulus value for our nanotubes which both validates the thermally driven

  11. A Remote Sensor for Detecting Methane Based on Palladium-Decorated Single Walled Carbon Nanotubes

    PubMed Central

    Liu, Jian; Li, Guomin

    2013-01-01

    The remote detection of the concentration of methane at room temperature is performed by a sensor that is configured by the combination of radio frequency identification (RFID), and functionalized carbon nanotubes (CNTs). The proposed sensor is schemed as a thin film RFID tag in a polyethylene substrate, on which a metal trace dipole, a metal trace T impedance matching networks, a 0.5 μm-CMOS RF/DC rectifier chipset and a sensor head of palladium-decorated single walled carbon nanotubes (Pd-SWCNTs) are surface mounted in cascade. The performances of the sensor are examined and described by the defined parameters of the received signal strength index (RSSI) and the comparative analog identifier (ΔAID). Results validate the sensor's ability to detect molecules of methane at room temperature, showing that the RSSI can increase 4 dB and the ΔAID can increase 3% in response to methane concentrations ranging from zero to 100 ppm. PMID:23845931

  12. Can trans-polyacetylene be formed on single-walled carbon-doped boron nitride nanotubes?

    PubMed

    Chen, Ying; Wang, Hong-xia; Zhao, Jing-xiang; Cai, Qing-hai; Wang, Xiao-guang; Wang, Xuan-zhang

    2012-07-01

    Recently, the grafting of polymer chains onto nanotubes has attracted increasing attention as it can potentially be used to enhance the solubility of nanotubes and in the development of novel nanotube-based devices. In this article, based on density functional theory (DFT) calculations, we report the formation of trans-polyacetylene on single-walled carbon-doped boron nitride nanotubes (BNNTs) through their adsorption of a series of C(2)H(2) molecules. The results show that, rather than through [2 + 2] cycloaddition, an individualmolecule would preferentially attach to a carbon-doped BNNT via "carbon attack" (i.e., a carbon in the C(2)H(2) attacks a site on the BNNT). The adsorption energy gradually decreases with increasing tube diameter. The free radical of the carbon-doped BNNT is almost completely transferred to the carbon atom at the end of the adsorbed C(2)H(2) molecule. When another C(2)H(2) molecule approaches the carbon-doped BNNT, it is most energetically favorable for this C(2)H(2) molecule to be adsorbed at the end of the previously adsorbed C(2)H(2) molecule, and so on with extra C(2)H(2) molecules, leading to the formation of polyacetylene on the nanotube. The spin of the whole system is always localized at the tip of the polyacetylene formed, which initiates the adsorption of the incoming species. The present results imply that carbon-doped BNNT is an effective "metal-free" initiator for the formation of polyacetylene.

  13. Cloning single wall carbon nanotubes for hydrogen storage

    SciTech Connect

    Tour, James M; Kittrell, Carter

    2012-08-30

    The purpose of this research is to development the technology required for producing 3-D nano-engineered frameworks for hydrogen storage based on sp2 carbon media, which will have high gravimetric and especially high volumetric uptake of hydrogen, and in an aligned fibrous array that will take advantage of the exceptionally high thermal conductivity of sp2 carbon materials to speed up the fueling process while minimizing or eliminating the need for internal cooling systems. A limitation for nearly all storage media using physisorption of the hydrogen molecule is the large amount of surface area (SA) occupied by each H2 molecule due to its large zero-point vibrational energy. This creates a conundrum that in order to maximize SA, the physisorption media is made more tenuous and the density is decreased, usually well below 1 kg/L, so that there comes a tradeoff between volumetric and gravimetric uptake. Our major goal was to develop a new type of media with high density H2 uptake, which favors volumetric storage and which, in turn, has the capability to meet the ultimate DoE H2 goals.

  14. Transparent silica glasses containing single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    DiMaio, Jeffrey R.; Rhyne, Suzette L.; Ballato, John M.; Czerw, Richard; Xu, Jianfeng; Webster, Scott; Carroll, David L.; Fu, Kefu; Sun, Ya-Ping

    2001-11-01

    Organic - Inorganic matrix nano composites have been created using an acid catalyzed, tetraethyl orthosilicate-based sol- gel technique with SWNTs. By utilizing nanotubes functionalized with the dendron methyl 3,5- di(methyltrigycoloxy)benzylic alcohol, ultrasonication blending in the sol phase prior to gelation yields excellent dispersion characteristics of the nanotube phase. Further, glasses could easily be dried by heating to 600 degrees C yielding 80 percent of theoretical density wit little change in the nanotube content. These materials exhibited intrinsic Rayleigh scattering, suggesting near ideal dispersion. Nonlinear optical transmissivity was observed for 1064 and 532 nm light suggesting that the matrix has a strong broad band coupling to the optical field. Such composites allow for a host of applications based on the novel confinement properties of carbon nanotubes in a robust host.

  15. An alternate mathematical model for single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cotfas, Nicolae

    2005-09-01

    The positions of atoms forming a carbon nanotube are usually described by using a system of generators of the symmetry group. Each atomic position corresponds to an element of the set Z×{0,1,…,n}×{0,1}, where n is a natural number depending on the considered nanotube. We obtain an alternate rather different description by starting from a description of the honeycomb lattice in terms of Miller indices. In our mathematical model which is a factor space defined by an equivalence relation in the set {(v0,v1,v2)∈Z|v0+v1+v2∈{0,1}} the neighbours of an atomic position can be described in a simpler way, and the mathematical objects with geometric or physical significance have a simpler and more symmetric form.

  16. Advantages of flattened electrode in bottom contact single-walled carbon nanotube field-effect transistor

    SciTech Connect

    Setiadi, Agung; Akai-Kasaya, Megumi Saito, Akira; Kuwahara, Yuji

    2014-09-01

    We fabricated single-walled carbon nanotube (SWNT) field-effect transistor (FET) devices on flattened electrodes, in which there are no height difference between metal electrodes and the substrate. SWNT-FET fabricated using bottom contact technique have some advantages, such that the SWNTs are free from electron irradiation, have direct contact with the desired metal electrodes, and can be functionalized before or after deposition. However, the SWNTs can be bent at the contact point with the metal electrodes leading to a different electrical characteristic of the devices. The number of SWNT direct junctions in short channel length devices is drastically increased by the use of flattened electrodes due to strong attractive interaction between SWNT and the substrate. The flattened electrodes show a better balance between their hole and electron mobility compared to that of the non-flattened electrodes, that is, ambipolar FET characteristic. It is considered that bending of the SWNTs in the non-flattened electrode devices results in a higher Schottky barrier for the electrons.

  17. Microwave and Millimeter Wave Properties of Vertically-Aligned Single Wall Carbon Nanotubes Films

    NASA Astrophysics Data System (ADS)

    Haddadi, K.; Tripon-Canseliet, C.; Hivin, Q.; Ducournau, G.; Teo, E.; Coquet, P.; Tay, B. K.; Lepilliet, S.; Avramovic, V.; Chazelas, J.; Decoster, D.

    2016-05-01

    We present the experimental determination of the complex permittivity of vertically aligned single wall carbon nanotubes (SWCNTs) films grown on quartz substrates in the microwave regime from 10 MHz up to 67 GHz, with the electrical field perpendicular to the main axis of the carbon nanotubes (CNTs), based on coplanar waveguide transmission line approach together with the measurement of the microwave impedance of top metalized vertically—aligned SWCNTs grown on conductive silicon substrates up to 26 GHz. From coplanar waveguide measurements, we obtain a real part of the permittivity almost equal to unity, which is interpreted in terms of low carbon atom density (3 × 1019 at/cm3) associated with a very low imaginary part of permittivity (<10-3) in the frequency range considered due to a very small perpendicular conductivity. The microwave impedance of a vertically aligned CNTs bundle equivalent to a low resistance reveals a good conductivity (3 S/cm) parallel to the CNTs axis. From these two kinds of data, we experimentally demonstrate the tensor nature of the vertically grown CNTs bundles.

  18. Dispersion of Single Wall Carbon Nanotubes by in situ Polymerization Under Sonication

    NASA Technical Reports Server (NTRS)

    Park, Cheol; Ounaies, Zoubeida; Watson, Kent A.; Crooks, Roy E.; Smith, Joseph, Jr.; Lowther, Sharon E.; Connell, John W.; Siochi, Emilie J.; Harrison, Joycelyn S.; St.Clair, Terry L.

    2002-01-01

    Single wall nanotube reinforced polyimide nanocomposites were synthesized by in situ polymerization of monomers of interest in the presence of sonication. This process enabled uniform dispersion of single wall carbon nanotube (SWNT) bundles in the polymer matrix. The resultant SWNT-polyimide nanocomposite films were electrically conductive (antistatic) and optically transparent with significant conductivity enhancement (10 orders of magnitude) at a very low loading (0.1 vol%). Mechanical properties as well as thermal stability were also improved with the incorporation of the SWNT.

  19. Discotic ionic liquid crystals of triphenylene as dispersants for orienting single-walled carbon nanotubes.

    PubMed

    Lee, Jeongho Jay; Yamaguchi, Akihisa; Alam, Md Akhtarul; Yamamoto, Yohei; Fukushima, Takanori; Kato, Kenichi; Takata, Masaki; Fujita, Norifumi; Aida, Takuzo

    2012-08-20

    Orient and conduct: Triphenylene-based discotic ionic liquid crystals (ILCs) with six imidazolium ion pendants can disperse pristine single-walled carbon nanotubes (SWNTs). When the ILC is columnarly assembled, doping with SWNTs results in macroscopic homeotropic columnar orientation. Combination of shear and annealing treatments gives rise to three different orientation states, which determine the anisotropy of electrical conduction.

  20. Aggregation Kinetics and Transport of Single-Walled CarbonNanotubes at Low Surfactant Concentrations

    EPA Science Inventory

    Little is known about how low levels of surfactants can affect the colloidal stability of single-walled carbon nanotubes (SWNTs) and how surfactant-wrapping of SWNTs can impact ecological exposures in aqueous systems. In this study, SWNTs were suspended in water with sodium ...

  1. MICROWAVE-INDUCED RAPID CHEMICAL FUNCTIONALIZATION OF SINGLE-WALLED CARBON NANOTUBES (R830901)

    EPA Science Inventory


    Abstract

    The microwave-induced chemical functionalization of single-walled carbon nanotubes (SWNTs) is reported. The major advantage of this high-energy procedure is that it reduced the reaction time to the order of minutes and the number of steps in the reac...

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

    PubMed

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

    2005-03-17

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

  3. Production of vertical arrays of small diameter single-walled carbon nanotubes

    DOEpatents

    Hauge, Robert H; Xu, Ya-Qiong

    2013-08-13

    A hot filament chemical vapor deposition method has been developed to grow at least one vertical single-walled carbon nanotube (SWNT). In general, various embodiments of the present invention disclose novel processes for growing and/or producing enhanced nanotube carpets with decreased diameters as compared to the prior art.

  4. Dispersion of single-walled carbon nanotubes in alcohol-cholic acid mixtures

    NASA Astrophysics Data System (ADS)

    Dyshin, A. A.; Eliseeva, O. V.; Bondarenko, G. V.; Kolker, A. M.; Zakharov, A. G.; Fedorov, M. V.; Kiselev, M. G.

    2013-12-01

    A procedure for dispersing single-walled carbon nanotubes (SWNTs) for the preparation of suspensions with high concentrations of individual nanotubes in various solvents was described. The most stable suspensions were obtained from a mixture of ethanol with cholic acid at an acid concentration of 0.018 mol/kg.

  5. On the Likelihood of Single-Walled Carbon Nanotubes Causing Adverse Marine Ecological Effects

    EPA Science Inventory

    This brief article discusses the ecological effects of single-walled carbon nanotubes (SWNTs)in the marine environment. Based on new research and a review of the scientific literature, the paper concludes that SWNTs are unlikely to cause adverse ecological effects in the marine ...

  6. Environmental Detection of Single-Walled Carbon Nanotubes Utilizing Near-Infrared Fluorescence

    EPA Science Inventory

    There are a growing number of applications for carbon nanotubes (CNT) in modern technologies and, subsequently, growth in production of CNT has expanded rapidly. Single-walled CNT (SWCNT) consist of a graphene sheet rolled up into a tube. With growing manufacture and use, the ...

  7. Multifunctional Materials: Transparent Reactive Armor Utilizing Single-Walled Carbon Nanotube Frameworks

    DTIC Science & Technology

    2010-03-03

    S. et al. Electronic structure control of single-walled carbon nanotube functionalization . Science 301, 1519- 1522 (2003). 13. Schoutissen, H. A...Unbundled and highly functionalized carbon nanotubes from aqueous reactions. Nano Letters 3, 1215-1218 (2003). 15. Brill, T. B. & James, K. J...Shenogin, S., Bodapati, A., Xue, L., Ozisik, R. & Keblinski, P. Effect of chemical functionalization on thermal transport of carbon nanotube composites

  8. Thermal transpiration through single walled carbon nanotubes and graphene channels

    SciTech Connect

    Thekkethala, Joe Francis; Sathian, Sarith P.

    2013-11-07

    Thermal transpiration through carbon nanotubes (CNTs) and graphene channels is studied using molecular dynamics (MD) simulations. The system consists of two reservoirs connected by a CNT. It is observed that a flow is developed inside the CNT from the low temperature reservoir to the high temperature reservoir when the two reservoirs are maintained at different temperatures. The influence of channel size and temperature gradient on the mean velocity is analysed by varying the CNT diameter and the temperature of one of the reservoirs. Larger flow rate is observed in the smaller diameter CNTs showing an increase in the mean velocity with increase in the temperature gradient. For the flow developed inside the CNTs, slip boundaries occur and the slip length is calculated using the velocity profile. We examine the effect of fluid-wall interaction strength (ε{sub fw}), diffusivity (D), and viscosity of the fluid (μ) on the temperature induced fluid transport through the CNTs. Similar investigations are also carried out by replacing the CNT with a graphene channel. Results show that the mean velocity of the fluid atoms in the graphene channel is lower than that through the CNTs. This can be attributed to the higher degree of confinement observed in the CNTs.

  9. Vibrational modes and thermal transformation of purified single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong

    Vibrational modes of single-walled carbon nanotubes (SWNTs) and graphitic nanoribbons (GNRs) were studied using Raman scattering and/or Fourier Transform Infrared Spectroscopies, Variations in a three-step purification scheme to remove amorphous carbon and residual catalyst were studied: (step 1) Oxidation, (step 2) Acid Reflux, and (step 3) Thermal Annealing were found to remove most amorphous carbon (oxidation step) and residual metal catalyst (acid reflux step) which were the major impurity phases. By combining IR and Raman, we found considerable wall damage and functional groups (e.g.-COOH and-OH) could be introduced via H2O2 and HNO3 reflux. Surprisingly, vacuum annealing at ˜1100°C for a few hours was found to remove most wall damage and functional groups. Methods to break up large (purified) bundles of single-walled carbon nanotubes (SWNTs) to individual tubes were also investigated. Amide solvents with ultrasound were found to be very effective in debundling; initial purification treatment strongly impacted the outcome. SWNT material decorated with functional groups (e.g., -COOH) tended to produce higher yields of single tubes. Length and diameter distributions of individual tubes were measured using Atomic Force Microscopy. Aggressive chemical debundling processes were found to lead to more functionalization, higher degree of debundling and shorter tubes. The IR-active modes of SWNTs was observed for the first time by transmission method, some ten years after the discovery of the Raman-active modes. In concert with theoretical calculations, we were able to assign much of the sharp structure in the IR with anticipated one- and two-phonon lattice mode bands. Thermal evolution of bundled SWNT materials produced in the electric arc (ARC) and by CVD in CO gas (HiPCO) was also investigated. Although both ARC and HiPCO evolved thermally to multi-walled tubes (MWNTs), we found using electron microscopy that for T>2000°C ARC SWNTs (with significantly narrower

  10. Highly Increased Flow-Induced Power Generation on Plasmonically Carbonized Single-Walled Carbon Nanotube .

    PubMed

    Kim, Jangheon; Lee, Janghyeon; Kim, Soohyun; Jung, Wonsuk

    2016-11-09

    We generate networks and carbonization between individualized single-walled carbon nanotubes (SWCNTs) by an optimized plasmonic heating process using a halogen lamp to improve electrical properties for flow-induced energy harvesting. These properties were characterized by Raman spectra, a field-emission-scanning probe, transmission electron microscopy, atomic force microscopy and thermographic camera. The electrical sheet resistance of carbonized SWCNTs was decreased to 2.71 kΩ/□, 2.5 times smaller than normal-SWCNTs. We demonstrated flow-induced voltage generation on SWCNTs at various ion concentrations of NaCl. The generated voltage and current for the carbonized-SWCNTs were 9.5 and 23.5 times larger than for the normal-SWCNTs, respectively, based on the electron dragging mechanism.

  11. Single-wall carbon nanotubes under high pressures to 62 GPa studied using designer diamond anvils.

    PubMed

    Patterson, J R; Vohra, Y K; Weir, S T; Akella, J

    2001-06-01

    Single-wall carbon nanotube samples were studied under high pressures to 62 GPa using designer diamond anvils with buried electrical microprobes that allowed for monitoring of the four-probe electrical resistance at elevated pressure. After initial densification, the electrical resistance shows a steady increase from 3 to 42 GPa, followed by a sharp rise above 42 GPa. This sharp rise in electrical resistance at high pressures is attributed to opening of an energy band gap with compression. Nanoindentation hardness measurements on the pressure-treated carbon nanotube samples gave a hardness value of 0.50 +/- 0.03 GPa. This hardness value is approximately 2 orders of magnitude lower than the amorphous carbon phase produced in fullerenes under similar conditions. Therefore, the pressure treatment of single-wall carbon nanotubes to 62 GPa did not produce a superhard carbon phase.

  12. Control of the Diameter and Chiral Angle Distributions during Production of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel

    2009-01-01

    Many applications of single wall carbon nanotubes (SWCNT), especially in microelectronics, will benefit from use of certain (n,m) nanotube types (metallic, small gap semiconductor, etc.) Especially fascinating is the possibility of quantum conductors that require metallic armchair nanotubes. However, as produced SWCNT samples are polydisperse, with many (n,m) types present and typical approx.1:2 metal/semiconductor ratio. Nanotube nucleation models predict that armchair nuclei are energetically preferential due to formation of partial triple bonds along the armchair edge. However, nuclei can not reach any meaningful thermal equilibrium in a rapidly expanding and cooling plume of carbon clusters, leading to polydispersity. In the present work, SWCNTs were produced by a pulsed laser vaporization (PLV) technique. The carbon vapor plume cooling rate was either increased by change in the oven temperature (expansion into colder gas), or decreased via "warm-up" with a laser pulse at the moment of nucleation. The effect of oven temperature and "warm-up" on nanotube type population was studied via photoluminescence, UV-Vis-NIR absorption and Raman spectroscopy. It was found that reduced temperatures leads to smaller average diameters, progressively narrower diameter distributions, and some preference toward armchair structures. "Warm-up" shifts nanotube population towards arm-chair structures as well, but the effect is small. Possible improvement of the "warm-up" approach to produce armchair SWCNTs will be discussed. These results demonstrate that PLV production technique can provide at least partial control over the nanotube (n,m) population. In addition, these results have implications for the understanding the nanotube nucleation mechanism in the laser oven.

  13. In situ mass spectroscopic analysis of alcohol catalytic chemical vapor deposition process for single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Tomie, Takashi; Inoue, Shuhei; Iba, Yushi; Matsumura, Yukihiko

    2012-05-01

    In situ mass spectroscopic analysis was carried out to clarify the growth mechanism of single-walled carbon nanotube grown by alcohol catalytic chemical vapor deposition. When catalysts were used, pyrolysis could be accomplished at a temperature of 600 °C; without the use of catalysts, successful pyrolysis required a temperature of more than 800 °C. Ethylene and acetylene are important products for the synthesis of carbon nanotubes, and fusion of the metal catalyst is the cause of failure of synthesis at high temperatures. This fact indicates that the degradation and polymerization of ethanol are not the cause of the failure of synthesis.

  14. Large scale combustion synthesis of single-walled carbon nanotubes and their characterization.

    PubMed

    Richter, Henning; Treska, Meri; Howard, Jack B; Wen, John Z; Thomasson, Sebastien B; Reading, Arthur A; Jardim, Paula M; Vander Sande, John B

    2008-11-01

    Since its invention in 1991, premixed combustion synthesis of fullerenic materials has been established as the major industrial process for manufacturing of these materials. Large-scale production of fullerenes such as C60, C70 and C84 has been implemented. More recently, combustion technology has been extended to the targeted synthesis of single-walled carbon nanotubes (SWCNT). Addition of catalyst precursor and operation at well-controlled fuel-rich but non-sooting conditions are required. Extensive parametric studies have allowed for the optimization of the formation of high-quality SWCNT. Purification techniques previously reported in the literature have been adjusted and used successfully for the nearly complete removal of metal and metal oxide. Material has been characterized using Raman spectroscopy, scanning (SEM) and transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Correlations between process conditions and nanotube properties such as length have been established. Product reproducibility and process scalability of the combustion process have been demonstrated. Sample preparation was found to affect significantly the apparent characteristics of nanotubes as seen in electron microscopy images.

  15. All-Organic Actuator Fabricated with Single Wall Carbon Nanotube Electrodes

    NASA Technical Reports Server (NTRS)

    Lowther, Sharon E.; Harrison, Joycelyn S.; Kang, Jinho; Park, Cheol; Park, Chan Eon

    2008-01-01

    Compliant electrodes to replace conventional metal electrodes have been required for many actuators to relieve the constraint on the electroactive layer. Many conducting polymers have been proposed for the alternative electrodes, but they still have a problem of poor thermal stability. This article reports a novel all-organic actuator with single wall carbon nanotube (SWCNT) films as the alternative electrode. The SWCNT film was obtained by filtering a SWCNT solution through an anodized alumina membrane. The conductivity of the SWCNT film was about 280 S/cm. The performance of the SWCNT film electrode was characterized by measuring the dielectric properties of NASA Langley Research Center - Electroactive Polymer (LaRC-EAP) sandwiched by the SWCNT electrodes over a broad range of temperature (from 25 C to 280 C) and frequency (from 1 KHz to 1 MHz). The all-organic actuator with the SWCNT electrodes showed a larger electric field-induced strain than that with metal electrodes, under identical measurement conditions.

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

    PubMed

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

    2013-09-11

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

  17. Enhanced adsorption of mercury ions on thiol derivatized single wall carbon nanotubes.

    PubMed

    Bandaru, Narasimha Murthy; Reta, Nekane; Dalal, Habibullah; Ellis, Amanda V; Shapter, Joseph; Voelcker, Nicolas H

    2013-10-15

    Thiol-derivatized single walled carbon nanotube (SWCNT-SH) powders were synthesized by reacting acid-cut SWCNTs with cysteamine hydrochloride using carbodiimide coupling. Infrared (IR) spectroscopy, Raman spectroscopy and thermogravimetric analysis confirmed the successful functionalization of the SWCNTs. SWCNT-SH powders exhibited a threefold higher adsorption capacity for Hg(II) ions compared to pristine SWCNTs, and a fourfold higher adsorption capacity compared to activated carbon. The influence of adsorption time, pH, initial metal concentration and adsorbent dose on Hg(II) ion removal was investigated. The maximum adsorption capacity of the SWCNT-SH powders was estimated by using equilibrium isotherms, such as Freundlich and Langmuir, and the maximum adsorption capacity of the SWCNT-SH powder was found to be 131 mg/g. A first-order rate model was employed to describe the kinetic adsorption process of Hg(II) ions onto the SWCNT-SH powders. Desorption studies revealed that Hg(II) ions could be easily removed from the SWCNT-SH powders by altering the pH. Further, the adsorption efficiency of recovered SWCNT-SH powders was retained up to 91%, even after 5 adsorption/desorption cycles.

  18. Debundling and dissolution of single-walled carbon nanotubes in amide solvents.

    PubMed

    Furtado, C A; Kim, U J; Gutierrez, H R; Pan, Ling; Dickey, E C; Eklund, Peter C

    2004-05-19

    Wet chemical methods involving ultrasound and amide solvents were used to purify and separate large bundles of single-walled carbon nanotubes (SWNTs) into individual nanotubes that could then be transported to silicon or mica substrates. The SWNTs studied were produced by the arc-discharge process. Dry oxidation was used in an initial step to remove amorphous carbon. Subsequently, two acid purification schemes were investigated (HCl- and HNO(3)-reflux) to remove the metal growth catalyst (Ni-Y). Finally, ultrasonic dispersion of isolated tubes into either N,N-dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP) was carried out. Raman scattering, atomic force microscopy (AFM), and electron microscopy were used to study the evolution of the products. Raman scattering was used to probe possible wall damage during the chemical processing. We found that both HCl and HNO(3) could be used to successfully remove the Ni-Y below approximately 1 wt %. However, the HNO(3)-reflux produced significant wall damage (that could be reversed by vacuum annealing at 1000 degrees C). In the dispersion step, both amide solvents (DMF and NMP) produced a high degree of isolated tubes in the final product, and no damage during this dispersion step was observed. HNO(3)-refluxed tubes were found to disperse the best into the amide solvents, perhaps because of significant wall functionalization. AFM was used to study the filament diameter and length distributions in the final product, and interesting differences in these distributions were observed, depending on the chemical processing route.

  19. Computational and experimental studies of the interaction between single-walled carbon nanotubes and folic acid

    NASA Astrophysics Data System (ADS)

    Castillo, John J.; Rozo, Ciro E.; Castillo-León, Jaime; Rindzevicius, Tomas; Svendsen, Winnie E.; Rozlosnik, Noemi; Boisen, Anja; Martínez, Fernando

    2013-03-01

    This Letter involved the preparation of a conjugate between single-walled carbon nanotubes and folic acid that was obtained without covalent chemical functionalization using a simple 'one pot' synthesis method. Subsequently, the conjugate was investigated by a computational hybrid method: our own N-layered Integrated Molecular Orbital and Molecular Mechanics (B3LYP(6-31G(d):UFF)). The results confirmed that the interaction occurred via hydrogen bonding between protons of the glutamic moiety from folic acid and π electrons from the carbon nanotubes. The single-walled carbon nanotube-folic acid conjugate presented herein is believed to lead the way to new potential applications as carbon nanotube-based drug delivery systems.

  20. Single-walled carbon nanotube/polyaniline/n-silicon solar cells: fabrication, characterization, and performance measurements.

    PubMed

    Tune, Daniel D; Flavel, Benjamin S; Quinton, Jamie S; Ellis, Amanda V; Shapter, Joseph G

    2013-02-01

    Carbon nanotube-silicon solar cells are a recently investigated photovoltaic architecture with demonstrated high efficiencies. Silicon solar-cell devices fabricated with a thin film of conductive polymer (polyaniline) have been reported, but these devices can suffer from poor performance due to the limited lateral current-carrying capacity of thin polymer films. Herein, hybrid solar-cell devices of a thin film of polyaniline deposited on silicon and covered by a single-walled carbon nanotube film are fabricated and characterized. These hybrid devices combine the conformal coverage given by the polymer and the excellent electrical properties of single-walled carbon nanotube films and significantly outperform either of their component counterparts. Treatment of the silicon base and carbon nanotubes with hydrofluoric acid and a strong oxidizer (thionyl chloride) leads to a significant improvement in performance.

  1. Multifunctional Materials: Transparent Reactive Armor Utilizing Single-Walled Carbon Nanotube Frameworks

    DTIC Science & Technology

    2010-03-02

    control of single-walled carbon nanotube functionalization . Science 301, 1519- 1522 (2003). 13. Schoutissen, H. A. J. The Diazotization of Very Weakly...R. & Keblinski, P. Effect of chemical functionalization on thermal transport of carbon nanotube composites. Applied Physics Letters 85, 2229-2231...1 The goal of this project is to enable a new class of transparent energetic materials from nanotube -organic scaffolds, evaluate the feasibility

  2. Single Wall Carbon Nanotube Alignment Mechanisms for Non-Destructive Evaluation

    NASA Technical Reports Server (NTRS)

    Hong, Seunghun

    2002-01-01

    As proposed in our original proposal, we developed a new innovative method to assemble millions of single wall carbon nanotube (SWCNT)-based circuit components as fast as conventional microfabrication processes. This method is based on surface template assembly strategy. The new method solves one of the major bottlenecks in carbon nanotube based electrical applications and, potentially, may allow us to mass produce a large number of SWCNT-based integrated devices of critical interests to NASA.

  3. Dynamic elastic modulus of single-walled carbon nanotubes in different thermal environments

    NASA Astrophysics Data System (ADS)

    Liu, T. T.; Wang, X.

    2007-05-01

    This Letter reports the result of investigation on the effect of loading rate (strain rate) on mechanical properties of armchair and zigzag nanotubes in different thermal environments, based on the molecular structural mechanics model in which the primary bonds between two nearest-neighboring carbon atoms are treaded as dimensional 2-node Euler Bernoulli beam considering the effect of environmental temperature on force constant values of the bonds stretching, bonds angle bending and torsional resistance. Nanoscale finite element simulations of the dynamic Young's modulus of single-walled carbon nanotubes under different strain rates and environmental temperatures reveal that the dynamic Young's modulus of the single-walled carbon nanotubes increases with the increase of strain rate, and decreases significantly with the increase of environment temperature. It is significant that the dynamic Young's modulus of zigzag nanotubes is more sensitive to strain rate and environmental temperature due to the tube chirality.

  4. Review of Laser Ablation Process for Single Wall Carbon Nanotube Production

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram

    2003-01-01

    Different types of lasers are now routinely used to prepare single wall carbon nanotubes (SWCNTs). The original method developed by researchers at Rice University utilized a "double pulse laser oven" process. A graphite target containing about 1 atomic percent of metal catalysts is ablated inside a 1473K oven using laser pulses (10 ns pulse width) in slow flowing argon. Two YAG lasers with a green pulse (532 nm) followed by an IR pulse (1064 nm) with a 50 ns delay are used for ablation. This set up produced single wall carbon nanotube material with about 70% purity having a diameter distribution peaked around 1.4 nm. The impurities consist of fullerenes, metal catalyst clusters (10 to 100 nm diameter) and amorphous carbon. The rate of production with the initial set up was about 60 mg per hour with 10Hz laser systems. Several researchers have used variations of the lasers to improve the rate, consistency and study effects of different process parameters on the quality and quantity of SWCNTs. These variations include one to three YAG laser systems (Green, Green and IR), different pulse widths (nano to microseconds as well as continuous) and different laser wavelengths (Alexandrite, CO, CO2, free electron lasers in the near to far infrared). It is noted that yield from the single laser (Green or IR) systems is only a fraction of the two laser systems. The yield seemed to scale up with the repetition rate of the laser systems (10 to 60 Hz) and depended on the beam uniformity and quality of the laser pulses. The shift to longer wavelength lasers (free electron, CO and CO2) did not improve the quality, but increased the rate of production because these lasers are either continuous (CW) or high repetition rate pulses (kHz to MHz). The average power and the peak power of the lasers seem to influence the yields. Very high peak powers (MegaWatts per square centimeter) are noted to increase ablation of bigger particles with reduced yields of SWCNTs. Increased average powers

  5. Near-infrared exciton-polaritons in strongly coupled single-walled carbon nanotube microcavities

    PubMed Central

    Graf, Arko; Tropf, Laura; Zakharko, Yuriy; Zaumseil, Jana; Gather, Malte C.

    2016-01-01

    Exciton-polaritons form upon strong coupling between electronic excitations of a material and photonic states of a surrounding microcavity. In organic semiconductors the special nature of excited states leads to particularly strong coupling and facilitates condensation of exciton-polaritons at room temperature, which may lead to electrically pumped organic polariton lasers. However, charge carrier mobility and photo-stability in currently used materials is limited and exciton-polariton emission so far has been restricted to visible wavelengths. Here, we demonstrate strong light-matter coupling in the near infrared using single-walled carbon nanotubes (SWCNTs) in a polymer matrix and a planar metal-clad cavity. By exploiting the exceptional oscillator strength and sharp excitonic transition of (6,5) SWCNTs, we achieve large Rabi splitting (>110 meV), efficient polariton relaxation and narrow band emission (<15 meV). Given their high charge carrier mobility and excellent photostability, SWCNTs represent a promising new avenue towards practical exciton-polariton devices operating at telecommunication wavelengths. PMID:27721454

  6. Near-infrared exciton-polaritons in strongly coupled single-walled carbon nanotube microcavities

    NASA Astrophysics Data System (ADS)

    Graf, Arko; Tropf, Laura; Zakharko, Yuriy; Zaumseil, Jana; Gather, Malte C.

    2016-10-01

    Exciton-polaritons form upon strong coupling between electronic excitations of a material and photonic states of a surrounding microcavity. In organic semiconductors the special nature of excited states leads to particularly strong coupling and facilitates condensation of exciton-polaritons at room temperature, which may lead to electrically pumped organic polariton lasers. However, charge carrier mobility and photo-stability in currently used materials is limited and exciton-polariton emission so far has been restricted to visible wavelengths. Here, we demonstrate strong light-matter coupling in the near infrared using single-walled carbon nanotubes (SWCNTs) in a polymer matrix and a planar metal-clad cavity. By exploiting the exceptional oscillator strength and sharp excitonic transition of (6,5) SWCNTs, we achieve large Rabi splitting (>110 meV), efficient polariton relaxation and narrow band emission (<15 meV). Given their high charge carrier mobility and excellent photostability, SWCNTs represent a promising new avenue towards practical exciton-polariton devices operating at telecommunication wavelengths.

  7. Near-infrared exciton-polaritons in strongly coupled single-walled carbon nanotube microcavities.

    PubMed

    Graf, Arko; Tropf, Laura; Zakharko, Yuriy; Zaumseil, Jana; Gather, Malte C

    2016-10-10

    Exciton-polaritons form upon strong coupling between electronic excitations of a material and photonic states of a surrounding microcavity. In organic semiconductors the special nature of excited states leads to particularly strong coupling and facilitates condensation of exciton-polaritons at room temperature, which may lead to electrically pumped organic polariton lasers. However, charge carrier mobility and photo-stability in currently used materials is limited and exciton-polariton emission so far has been restricted to visible wavelengths. Here, we demonstrate strong light-matter coupling in the near infrared using single-walled carbon nanotubes (SWCNTs) in a polymer matrix and a planar metal-clad cavity. By exploiting the exceptional oscillator strength and sharp excitonic transition of (6,5) SWCNTs, we achieve large Rabi splitting (>110 meV), efficient polariton relaxation and narrow band emission (<15 meV). Given their high charge carrier mobility and excellent photostability, SWCNTs represent a promising new avenue towards practical exciton-polariton devices operating at telecommunication wavelengths.

  8. Chirality-Controlled Synthesis and Applications of Single-Wall Carbon Nanotubes.

    PubMed

    Liu, Bilu; Wu, Fanqi; Gui, Hui; Zheng, Ming; Zhou, Chongwu

    2017-01-24

    Preparation of chirality-defined single-wall carbon nanotubes (SWCNTs) is the top challenge in the nanotube field. In recent years, great progress has been made toward preparing single-chirality SWCNTs through both direct controlled synthesis and postsynthesis separation approaches. Accordingly, the uses of single-chirality-dominated SWCNTs for various applications have emerged as a new front in nanotube research. In this Review, we review recent progress made in the chirality-controlled synthesis of SWCNTs, including metal-catalyst-free SWCNT cloning by vapor-phase epitaxy elongation of purified single-chirality nanotube seeds, chirality-specific growth of SWCNTs on bimetallic solid alloy catalysts, chirality-controlled synthesis of SWCNTs using bottom-up synthetic strategy from carbonaceous molecular end-cap precursors, etc. Recent major progresses in postsynthesis separation of single-chirality SWCNT species, as well as methods for chirality characterization of SWCNTs, are also highlighted. Moreover, we discuss some examples where single-chirality SWCNTs have shown clear advantages over SWCNTs with broad chirality distributions. We hope this review could inspire more research on the chirality-controlled preparation of SWCNTs and equally important inspire the use of single-chirality SWCNT samples for more fundamental studies and practical applications.

  9. Single-Walled Carbon Nanotube-Polyamidoamine Dendrimer Hybrids for Heterogeneous Catalysis.

    PubMed

    Giacalone, Francesco; Campisciano, Vincenzo; Calabrese, Carla; La Parola, Valeria; Syrgiannis, Zois; Prato, Maurizio; Gruttadauria, Michelangelo

    2016-04-26

    We report the synthesis and catalytic properties of single-walled carbon nanotube-polyamidoamine dendrimers hybrids (SWCNT-PAMAM), prepared via a convergent strategy. The direct reaction of cystamine-based PAMAM dendrimers (generations 2.5 and 3.0) with pristine SWCNTs in refluxing toluene, followed by immobilization and reduction of [PdCl4](2-), led to the formation of highly dispersed small palladium nanoparticles homogeneously confined throughout the nanotube length. One of these functional materials proved to be an efficient catalyst in Suzuki and Heck reactions, able to promote the above processes down to 0.002 mol % showing a turnover number (TON) of 48 000 and a turnover frequency (TOF) of 566 000 h(-1). In addition, the hybrid material could be recovered and recycled for up to 6 times. No leaching of the metal has been detected during the Suzuki coupling. Additional experiments carried out on the spent catalyst permitted to suggest that a "release and catch" mechanism is operative in both reactions, although during Heck reaction small catalytically active soluble Pd species are also present.

  10. Porphyrins-Functionalized Single-Walled Carbon Nanotubes Chemiresistive Sensor Arrays for VOCs.

    PubMed

    Shirsat, Mahendra D; Sarkar, Tapan; Kakoullis, James; Myung, Nosang V; Konnanath, Bharatan; Spanias, Andreas; Mulchandani, Ashok

    2012-09-02

    Single-walled carbon nanotubes (SWNTs) have been used extensively for sensor fabrication due to its high surface to volume ratio, nanosized structure and interesting electronic property. Lack of selectivity is a major limitation for SWNTs-based sensors. However, surface modification of SWNTs with a suitable molecular recognition system can enhance the sensitivity. On the other hand, porphyrins have been widely investigated as functional materials for chemical sensor fabrication due to their several unique and interesting physico-chemical properties. Structural differences between free-base and metal substituted porphyrins make them suitable for improving selectivity of sensors. However, their poor conductivity is an impediment in fabrication of prophyrin-based chemiresistor sensors. The present attempt is to resolve these issues by combining freebase- and metallo-porphyrins with SWNTs to fabricate SWNTs-porphyrin hybrid chemiresistor sensor arrays for monitoring volatile organic carbons (VOCs) in air. Differences in sensing performance were noticed for porphyrin with different functional group and with different central metal atom. The mechanistic study for acetone sensing was done using field-effect transistor (FET) measurements and revealed that the sensing mechanism of ruthenium octaethyl porphyrin hybrid device was governed by electrostatic gating effect, whereas iron tetraphenyl porphyrin hybrid device was governed by electrostatic gating and Schottky barrier modulation in combination. Further, the recorded electronic responses for all hybrid sensors were analyzed using a pattern-recognition analysis tool. The pattern-recognition analysis confirmed a definite pattern in response for different hybrid material and could efficiently differentiate analytes from one another. This discriminating capability of the hybrid nanosensor devices open up the possibilities for further development of highly dense nanosensor array with suitable porphyrin for E-nose application.

  11. Toxicity of single-wall carbon nanotubes functionalized with polyethylene glycol in zebrafish (Danio rerio) embryos.

    PubMed

    Girardi, Felipe A; Bruch, Gisele E; Peixoto, Carolina S; Dal Bosco, Lidiane; Sahoo, Sangram K; Gonçalves, Carla O F; Santos, Adelina P; Furtado, Clascídia A; Fantini, Cristiano; Barros, Daniela M

    2017-02-01

    Single-wall carbon nanotubes functionalized with polyethylene glycol (SWCNT-PEG) are promising materials for biomedical applications such as diagnostic devices and controlled drug-release systems. However, several questions about their toxicological profile remain unanswered. Thus, the aim of this study was to investigate the action of SWCNT-PEG in Danio rerio zebrafish embryos at the molecular, physiological and morphological levels. The SWCNT used in this study were synthesized by the high-pressure carbon monoxide process, purified and then functionalized with distearoyl phosphatidylethanolamine block copolymer-PEG (molecular weight 2 kDa). The characterization process was carried out with low-resolution transmission electron microscopy, thermogravimetric analysis and Raman spectroscopy. Individual zebrafish embryos were exposed to the SWCNT-PEG. Toxic effects occurred only at the highest concentration tested (1 ppm) and included high mortality rates, delayed hatching and decreased total larval length. For all the concentrations tested, the alkaline comet assay revealed no genotoxicity, and Raman spectroscopy measurements on the histological slices revealed no intracellular nanotubes. The results shown here demonstrate that SWCNT-PEG has low toxicity in zebrafish embryos, but more studies are needed to understand what mechanisms are involved. However, the presence of residual metals is possibly among the primary mechanisms responsible for the toxic effects observed, because the purification process was not able to remove all metal contamination, as demonstrated by the thermogravimetric analysis. More attention must be given to the toxicity of these nanomaterials before they are used in biomedical applications. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Single-Walled Carbon Nanotubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems

    DOE PAGES

    Upadhyayula, Venkata K. K.; Ghoshroy, Soumitra; Nair, Vinod S.; ...

    2008-01-01

    Tmore » he possibility of using single-walled carbon nanotubes (SWCNTs) aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies.he Freundlich adsorption equilibrium constant ( k ) for S.aureus and E.coli determined from batch adsorption study was found to be 9 × 10 8 and 2 × 10 8  ml/g, respectively.he visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen.he results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability.his is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.« less

  13. Self-assembly of single-walled carbon nanotubes into multiwalled carbon nanotubes in water: molecular dynamics simulations.

    PubMed

    Zou, Jian; Ji, Baohua; Feng, Xi-Qiao; Gao, Huajian

    2006-03-01

    We report discoveries from a series of molecular dynamics simulations that single-walled carbon nanotubes, with different diameters, lengths, and chiralities, can coaxially self-assemble into multiwalled carbon nanotubes in water via spontaneous insertion of smaller tubes into larger ones. The assembly process is tube-size-dependent, and the driving force is primarily the intertube van der Waals interactions. The simulations also suggest that a multiwalled carbon nanotube may be separated into single-walled carbon nanotubes under appropriate solvent conditions. This study suggests possible bottom-up self-assembly routes for the fabrication of novel nanodevices and systems.

  14. Single Walled Carbon Nanotubes as Reporters for the Optical Detection of Glucose

    PubMed Central

    Barone, Paul W.; Strano, Michael S.

    2009-01-01

    This article reviews current efforts to make glucose sensors based on the inherent optical properties of single walled carbon nanotubes. The advantages of single walled carbon nanotubes over traditional organic and nanoparticle fluorophores for in vivo-sensing applications are discussed. Two recent glucose sensors made by our group are described, with the first being an enzyme-based glucose sensor that couples a reaction mediator, which quenches nanotube fluorescence, on the surface of the nanotube with the reaction of the enzyme. The second sensor is based on competitive equilibrium binding between dextran-coated nanotubes and concanavalin A. The biocompatibility of a model sensor is examined using the chicken embryo chorioallantoic membrane as a tissue model. The advantages of measuring glucose concentration directly, like most optical sensors, versus measuring the flux in glucose concentration, like most electrochemical sensors, is discussed. PMID:20144355

  15. Synthesis of Single Wall Carbon Nanotubes by Plasma Arc: Role of Plasma Parameters

    NASA Technical Reports Server (NTRS)

    Farhart, Samir; Scott, Carl D.

    2000-01-01

    Single wall carbon nanotubes (SWNT) are porous objects on the molecular scale and have a low density, which gives them potential applications as adsorbent for molecular hydrogen. Their H2 absorption capacity published in the literature varies from 4 to 10% by mass according to the purity of the materials and storage conditions. Optimization of production methods of SWNTs should permit improving these new materials for storage of hydrogen. In this article, we show the potential of using SWNTs in hydrogen storage. In particular, we pose problems associated with synthesis, purification, and opening up of the nanotubes. We present an electric arc process currently used at laboratory scale to produce single wall carbon nanotubes. We discuss, in particular, operating conditions that permit growth of nanotubes and some plasma parameters that assure control of the material. Analysis of the process is carried out with the aid of local measurements of temperature and scanning and transmission electron microscopy of the materials.

  16. G-quartet type self-assembly of guanine functionalized single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Singh, Prabhpreet; Venkatesh, V.; Nagapradeep, N.; Verma, Sandeep; Bianco, Alberto

    2012-03-01

    The simple strategy of linking guanine to single-walled carbon nanotubes (CNTs) through covalent functionalization permitted generation of the alignment of the nanotubes into lozenges reminiscent of guanine quartets (G-quartets) in the presence of potassium ions as observed by atomic force microscopy.The simple strategy of linking guanine to single-walled carbon nanotubes (CNTs) through covalent functionalization permitted generation of the alignment of the nanotubes into lozenges reminiscent of guanine quartets (G-quartets) in the presence of potassium ions as observed by atomic force microscopy. Electronic supplementary information (ESI) available: Experimental procedures for the synthesis and characterization of the precursors and MWCNT conjugates. See DOI: 10.1039/c2nr11849a

  17. Rings and rackets from single-wall carbon nanotubes: manifestations of mesoscopic mechanics

    NASA Astrophysics Data System (ADS)

    Wang, Yuezhou; Semler, Matthew; Ostanin, Igor; Hobbie, Erik; Dumitrica, Traian

    2015-03-01

    We combine distinct element method simulations and experiments to understand the stability of rings and rackets formed by single-walled carbon nanotubes assembled into ropes. Bending remains a soft deformation mode in ropes because intra-rope sliding of the constituent nanotubes occurs with ease. Our simulations indicate that the formation of these aggregates can be attributed to the mesoscopic mechanics of entangled nanotubes and to the sliding at the contacts. Starting from the single-walled carbon nanotubes, the sizes of the rings and rackets' heads increase with the rope diameter, indicating that the stability of the experimental aggregates can be largely explained by the competition between bending and van der Waals adhesion energies. Our results and simulation method should be useful for understanding nanoscale fibers and self-assembling process in general.

  18. Rings and rackets from single-wall carbon nanotubes: manifestations of mesoscale mechanics.

    PubMed

    Wang, Yuezhou; Semler, Matthew R; Ostanin, Igor; Hobbie, Erik K; Dumitrică, Traian

    2014-11-21

    We combine experiments and distinct element method simulations to understand the stability of rings and rackets formed by single-walled carbon nanotubes assembled into ropes. Bending remains a soft deformation mode in ropes because intra-rope sliding of the constituent nanotubes occurs with ease. Our simulations indicate that the formation of these aggregates can be attributed to the mesoscopic mechanics of entangled nanotubes and to the sliding at the contacts. Starting from the single-walled carbon nanotubes, the sizes of the rings and rackets' heads increase with the rope diameter, indicating that the stability of the experimental aggregates can be largely explained by the competition between bending and van der Waals adhesion energies. Our results and simulation method should be useful for understanding nanoscale fibers in general.

  19. Controlled reversible debundling of single-walled carbon nanotubes by photo-switchable dendritic surfactants

    NASA Astrophysics Data System (ADS)

    Kördel, Christian; Setaro, Antonio; Bluemmel, Pascal; Popeney, Chris S.; Reich, Stephanie; Haag, Rainer

    2012-05-01

    Stimulus responsive surfactants based on dendritic glycerol azobenzene conjugates were used to solubilize and debundle single-walled carbon nanotubes in aqueous media. Their debundling property as well as their reaggregation behavior upon irradiation with light was examined and light triggered reversible bundling and precipitation are shown.Stimulus responsive surfactants based on dendritic glycerol azobenzene conjugates were used to solubilize and debundle single-walled carbon nanotubes in aqueous media. Their debundling property as well as their reaggregation behavior upon irradiation with light was examined and light triggered reversible bundling and precipitation are shown. Electronic supplementary information (ESI) available: Experimental methods and more details about the switching process. See DOI: 10.1039/c2nr30305a

  20. Experimental determination of excitonic band structures of single-walled carbon nanotubes using circular dichroism spectra

    NASA Astrophysics Data System (ADS)

    Wei, Xiaojun; Tanaka, Takeshi; Yomogida, Yohei; Sato, Naomichi; Saito, Riichiro; Kataura, Hiromichi

    2016-10-01

    Experimental band structure analyses of single-walled carbon nanotubes have not yet been reported, to the best of our knowledge, except for a limited number of reports using scanning tunnelling spectroscopy. Here we demonstrate the experimental determination of the excitonic band structures of single-chirality single-walled carbon nanotubes using their circular dichroism spectra. In this analysis, we use gel column chromatography combining overloading selective adsorption with stepwise elution to separate 12 different single-chirality enantiomers. Our samples show higher circular dichroism intensities than the highest values reported in previous works, indicating their high enantiomeric purity. Excitonic band structure analysis is performed by assigning all observed Eii and Eij optical transitions in the circular dichroism spectra. The results reproduce the asymmetric structures of the valence and conduction bands predicted by density functional theory. Finally, we demonstrate that an extended empirical formula can estimate Eij optical transition energies for any (n,m) species.

  1. Experimental determination of excitonic band structures of single-walled carbon nanotubes using circular dichroism spectra

    PubMed Central

    Wei, Xiaojun; Tanaka, Takeshi; Yomogida, Yohei; Sato, Naomichi; Saito, Riichiro; Kataura, Hiromichi

    2016-01-01

    Experimental band structure analyses of single-walled carbon nanotubes have not yet been reported, to the best of our knowledge, except for a limited number of reports using scanning tunnelling spectroscopy. Here we demonstrate the experimental determination of the excitonic band structures of single-chirality single-walled carbon nanotubes using their circular dichroism spectra. In this analysis, we use gel column chromatography combining overloading selective adsorption with stepwise elution to separate 12 different single-chirality enantiomers. Our samples show higher circular dichroism intensities than the highest values reported in previous works, indicating their high enantiomeric purity. Excitonic band structure analysis is performed by assigning all observed Eii and Eij optical transitions in the circular dichroism spectra. The results reproduce the asymmetric structures of the valence and conduction bands predicted by density functional theory. Finally, we demonstrate that an extended empirical formula can estimate Eij optical transition energies for any (n,m) species. PMID:27703139

  2. Photoreactivity of carboxylated single-walled carbon nanotubes in sunlight: reactive oxygen species production in water.

    PubMed

    Chen, Chia-Ying; Jafvert, Chad T

    2010-09-01

    Very limited information exists on transformation processes of carbon nanotubes in the natural aquatic environment. Because the conjugated pi-bond structure of these materials is efficient in absorbing sunlight, photochemical transformations are a potential fate process with reactivity predicted to vary with their diameter, chirality, number and type of defects, functionalization, residual metal catalyst and amorphous carbon content, and with the composition of the water, including the type and composition of materials that act to disperse them into the aqueous environment. In this study, the photochemical reactions involving colloidal dispersions of carboxylated single-walled carbon nanotubes (SWNT-COOH) in sunlight were examined. Production of reactive oxygen species (ROS) during irradiation occurs and is evidence for potential further phototransformation and may be significant in assessing their overall environmental impacts. In aerated samples exposed to sunlight or to lamps that emit light only within the solar spectrum, the probe compounds, furfuryl alcohol (FFA), tetrazolium salts (NBT2+ and XTT), and p-chlorobenzoic acid (pCBA), were used to indicate production of 1O2, O2.-, and .OH, respectively. All three ROS were produced in the presence of SWNT-COOH and molecular oxygen (3O2). 1O2 production was confirmed by observing enhanced FFA decay in deuterium oxide, attenuated decay of FFA in the presence of azide ion, and the lack of decay of FFA in deoxygenated solutions. Photogeneration of O2.- and .OH was confirmed by applying superoxide dismutase (SOD) and tert-butanol assays, respectively. In air-equilibrated suspensions, the loss of 0.2 mM FFA in 10 mg/L SWNT-COOH was approximately 85% after 74 h. Production of 1O2 was not dependent on pH from 7 to 11; however photoinduced aggregation was observed at pH 3.

  3. Density Functional Studies of the 13C NMR Chemical Shifts in Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Zurek, Eva; Autschbach, Jochen

    2007-12-01

    Density functional theory has been used to compute the electronic structure and 13C NMR chemical shifts of finite (9,0) single-walled carbon nanotubes (SWNTs) capped with fullerene hemispheres and with hydrogen atoms. The chemical shifts and HOMO-LUMO gaps were found to be dependent upon the mode of capping. The shifts of semiconducting and metallic tubes were estimated as being around 130 ppm and 141 ppm, respectively. Periodic boundary calculations on infinite zigzag (n,0) SWNTs with 7⩽n⩽17 were performed. These entities can be characterized by a family index, λ = mod(n,3), and the chemical shifts can be fitted well by a function inversely proportional to the diameter of the tube and proportional to a constant which depends on the nanotube family. Direct comparison of the molecular and periodic approaches can be made if benzene is used as the internal reference. Such a comparison indicates that capping may have a strong effect on the computed properties. Calculations on infinite zigzag (7⩽n⩽10) amine functionalized SWNTs have been performed. The functional group may react with a C-C bond which is parallel or diagonal to the tube axis and both sites have been considered. The shifts of the carbons directly attached to the group are sensitive to the bond which has been functionalized and may therefore be used to discriminate between the two products. Functionalization induces a significant line broadening of the NMR signals but it does not dramatically change the average shift of the unfunctionalized SWNT carbons.

  4. Buckling Analysis of Chiral Single-Walled Carbon Nanotubes by Using the Nonlocal Timoshenko Beam Theory

    NASA Astrophysics Data System (ADS)

    Zidour, M.; Daouadji, T. H.; Benrahou, K. H.; Tounsi, A.; Adda Bedia, El A.; Hadji, L.

    2014-03-01

    On the basis of the nonlocal elasticity theory, the Timoshenko beam model is utilized to investigate the elastic buckling of chiral single-walled carbon nanotubes (SWCNTs) under axial compression. Based on the governing equations of the nonlocal Timoshenko beam model, an analytical solution for nonlocal critical buckling loads is obtained. The influence of a nonlocal small-scale coefficient, the vibration mode number, the chirality of SWWCNTs, and their aspect ratio on the nonlocal critical buckling loads is studied and discussed.

  5. Supramolecularly-knitted Tethered Oligopeptide/Single-walled Carbon Nanotube Organogels

    PubMed Central

    Zou, Jiong; He, Xun; Fan, Jingwei; Raymond, Jeffery E.

    2014-01-01

    A facile polymerization of an allyl-functional N-carboxyanhydride (NCA) monomer is utilized to construct an A-B-A type triblock structure containing β-sheet-rich oligomeric peptide segments tethered by a poly(ethylene oxide) chain, which are capable of dispersing and gelating single-walled carbon nanotubes (SWCNTs) noncovalently in organic solvents, resulting in significant enhancement of the mechanical properties of polypeptide-based organogels. PMID:24961389

  6. The Effects of Single-Wall Carbon Nanotubes on the Shear Piezoelectricity of Biopolymers

    NASA Technical Reports Server (NTRS)

    Lovell, Conrad; Fitz-Gerald, James M.; Harrison, Joycelyn S.; Park, Cheol

    2008-01-01

    Shear piezoelectricity was investigated in a series of composites consisting of increased loadings of single-wall carbon nanotubes (SWCNTs) in poly (gamma-benzyl-L-glutamate), or PBLG. The effects of the SWCNTs on this material property in PBLG will be discussed. Their influence on the morphology of the polymer (degree of orientation and crystallinity), and electrical and dielectric properties of the composite will be reported

  7. Bridged single-walled carbon nanotube-based atomic-scale mass sensors

    NASA Astrophysics Data System (ADS)

    Ali-Akbari, H. R.; Shaat, M.; Abdelkefi, A.

    2016-08-01

    The potentials of carbon nanotubes (CNTs) as mechanical resonators for atomic-scale mass sensing are presented. To this aim, a nonlocal continuum-based model is proposed to study the dynamic behavior of bridged single-walled carbon nanotube-based mass nanosensors. The carbon nanotube (CNT) is considered as an elastic Euler-Bernoulli beam with von Kármán type geometric nonlinearity. Eringen's nonlocal elastic field theory is utilized to model the interatomic long-range interactions within the structure of the CNT. This developed model accounts for the arbitrary position of the deposited atomic-mass. The natural frequencies and associated mode shapes are determined based on an eigenvalue problem analysis. An atom of xenon (Xe) is first considered as a specific case where the results show that the natural frequencies and mode shapes of the CNT are strongly dependent on the location of the deposited Xe and the nonlocal parameter of the CNT. It is also indicated that the first vibrational mode is the most sensitive when the mass is deposited at the middle of a single-walled carbon nanotube. However, when deposited in other locations, it is demonstrated that the second or third vibrational modes may be more sensitive. To investigate the sensitivity of bridged single-walled CNTs as mass sensors, different noble gases are considered, namely Xe, argon (Ar), and helium (He). It is shown that the sensitivity of the single-walled CNT to the Ar and He gases is much lower than the Xe gas due to the significant decrease in their masses. The derived model and performed analysis are so needed for mass sensing applications and particularly when the detected mass is randomly deposited.

  8. Fabrication of Discrete Nanosized Cobalt Particles Encapsulated Inside Single-Walled Carbon Nanotubes

    SciTech Connect

    Zoican Loebick, C.; Majewska, M; Ren, F; Haller, G; Pfefferle, L

    2010-01-01

    Single-walled carbon nanotubes (SWNT) with encapsulated nanosized cobalt particles have been synthesized by a facile and scalable method. In this approach, SWNT were filled with a cobalt acetylacetonate solution in dichloromethane by ultrasonication. In a second step, exposure to hydrogen at different temperatures released discrete cobalt particles of controllable size inside the SWNT cavity. The SWNT-Co particles systems were characterized by transmission electron microscopy, X-ray absorption spectroscopy, Raman spectroscopy, and thermal gravimetric analysis.

  9. Dispersion of Single-Walled Carbon Nanotubes in Poly(E-caprolactone)

    SciTech Connect

    Mitchell,C.; Krishnamoorti, R.

    2007-01-01

    The dispersion of single-walled carbon nanotubes (SWNT) in poly({var_epsilon}-caprolactone) with the aid of a zwitterionic surfactant is reported. Melt rheology and electrical conductivity measurements indicate geometrical percolation and electrical percolation for nanocomposites with {approx}0.08 wt % SWNT, implying an effective anisotropy for the nanotubes of at least 600. Spectroscopic measurements and comparison of dispersion using other surfactants established that the excellent dispersion is a result of the compatibilizing effect of the zwitterionic surfactant.

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

    DOE PAGES

    Márquez, Francisco; López, Vicente; Morant, Carmen; ...

    2010-01-01

    Arrmore » ays of vertically aligned single-walled carbon nanotube bundles, SWCNTs, have been synthesized by simple alcohol catalytic chemical vapor deposition process, carried out at 800°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.« less

  11. Single-Walled Carbon Nanotubes Targeted to the Tumor Vasculature for Breast Cancer Treatment

    DTIC Science & Technology

    2008-09-01

    plastic-immobilized phosphatidylserine ( PS ). Annexin V was conjugated with a suspension of single-walled carbon nanotubes (SWNTs) and carboxymethyl...of this complex to human endothelial cells with PS exposed on the cell surface showed strong binding, indicating that the covalently bound annexin V...been shown to bind to phospohatidylserine ( PS ) exposed on the surface of endothelial cells in blood vessels in tumors; PS is not exposed on the

  12. Raman mapping investigation of single-walled carbon nanotube bending in bottom-contact field-effect-transistor devices

    NASA Astrophysics Data System (ADS)

    Setiadi, Agung; Akai-Kasaya, Megumi; Kuwahara, Yuji

    2016-09-01

    We investigated the bending of single-walled carbon nanotubes (SWNTs) in bottom-contact SWNT devices using Raman mapping measurements. The height difference between the metal electrodes and the substrate caused the SWNTs to bend, down-shifting the G+ and G- bands of the bent SWNTs. No shifting of the G+ and G- bands was observed when flat electrodes were used. Shifting of the G+ and G- bands in SWNTs is strongly correlated to modulation of the Fermi level. We confirmed this effect by measuring the transport properties of the SWNT devices, which were in good agreement with the Raman measurement results.

  13. Temperature and voltage dependent current-voltage behavior of single-walled carbon nanotube transparent conducting films

    NASA Astrophysics Data System (ADS)

    Zhang, Ze-Chen; Geng, Hong-Zhang; Wang, Yan; Yang, Hai-Jie; Da, Shi-Xun; Ding, Er-Xiong; Liu, Juncheng; Yu, Ping; Fu, Yun-Qiao; Li, Xu; Pan, Hui

    2015-11-01

    High purified single-walled carbon nanotubes (SWCNTs) were dispersed in water and transparent conducting films (TCFs) were fabricated by a spray coating. The produced uniform SWCNT-TCFs treated by nitric acid have a relatively low sheet resistance and high transmittance. The current-voltage (I-V) behaviors of the TCFs were measured at room to higher temperature during the heating or cooling process. It was found that the I-V behavior of TCFs strongly dependent on the temperature and applied voltage. The sheet resistance showed semiconductor behavior at low temperature and low voltage, while it showed metallic behavior at high temperature and high voltage.

  14. A Novel Method for Characterizing the Diameter of Single-Wall Carbon Nanotubes by Optical Absorption Spectra

    NASA Astrophysics Data System (ADS)

    Saito, Takeshi; Ohmori, Shigekazu; Shukla, Bikau; Yumura, Motoo; Iijima, Sumio

    2009-09-01

    The potentiality of optical absorption spectroscopy (OAS) for the estimation of mean diameter of single-wall carbon nanotubes (SWCNTs) from electronic transition energies has been explored. The observed dependence of electronic transition energies of both metallic and semiconducting SWCNTs on their mean diameters clearly showed that transition energies scale inversely with the tube diameter. In the present study, the applicability of this estimation method has been experimentally confirmed for the diameter range of 1-2 nm and is expected to be useful for the characterization of wide range of diameters of SWNCTs.

  15. Enrichment of semiconducting single-walled carbon nanotubes by carbothermic reaction for use in all-nanotube field effect transistors.

    PubMed

    Li, Shisheng; Liu, Chang; Hou, Peng-Xiang; Sun, Dong-Ming; Cheng, Hui-Ming

    2012-11-27

    Selective removal of metallic single-walled carbon nanotubes (SWCNTs) and consequent enrichment of semiconducting SWCNTs were achieved through an efficient carbothermic reaction with a NiO thin film at a relatively low temperature of 350 °C. All-SWCNT field effect transistors (FETs) were fabricated with the aid of a patterned NiO mask, in which the as-grown SWCNTs behaving as source/drain electrodes and the remaining semiconducting SWCNTs that survive in the carbothermic reaction as a channel material. The all-SWCNT FETs demonstrate improved current ON/OFF ratios of ∼10(3).

  16. Carbon nanotube-nucleobase hybrids: nanorings from uracil-modified single-walled carbon nanotubes.

    PubMed

    Singh, Prabhpreet; Toma, Francesca Maria; Kumar, Jitendra; Venkatesh, V; Raya, Jesus; Prato, Maurizio; Verma, Sandeep; Bianco, Alberto

    2011-06-06

    Single-walled carbon nanotubes (SWCNTs) have been covalently functionalized with uracil nucleobase. The hybrids have been characterized by using complementary spectroscopic and microscopic techniques including solid-state NMR spectroscopy. The uracil-functionalized SWCNTs are able to self-assemble into regular nanorings with a diameter of 50-70 nm, as observed by AFM and TEM. AFM shows that the rings do not have a consistent height and thickness, which indicates that they may be formed by separate bundles of CNTs. The simplest model for the nanoring formation likely involves two bundles of CNTs interacting with each other via uracil-uracil base-pairing at both CNT ends. These nanorings can be envisaged for the development of advanced electronic circuits.

  17. Method for separating single-wall carbon nanotubes and compositions thereof

    NASA Technical Reports Server (NTRS)

    Smalley, Richard E. (Inventor); Hauge, Robert H. (Inventor); Kittrell, W. Carter (Inventor); Sivarajan, Ramesh (Inventor); Strano, Michael S. (Inventor); Bachilo, Sergei M. (Inventor); Weisman, R. Bruce (Inventor)

    2006-01-01

    The invention relates to a process for sorting and separating a mixture of (n, m) type single-wall carbon nanotubes according to (n, m) type. A mixture of (n, m) type single-wall carbon nanotubes is suspended such that the single-wall carbon nanotubes are individually dispersed. The nanotube suspension can be done in a surfactant-water solution and the surfactant surrounding the nanotubes keeps the nanotube isolated and from aggregating with other nanotubes. The nanotube suspension is acidified to protonate a fraction of the nanotubes. An electric field is applied and the protonated nanotubes migrate in the electric fields at different rates dependent on their (n, m) type. Fractions of nanotubes are collected at different fractionation times. The process of protonation, applying an electric field, and fractionation is repeated at increasingly higher pH to separated the (n, m) nanotube mixture into individual (n, m) nanotube fractions. The separation enables new electronic devices requiring selected (n, m) nanotube types.

  18. Unravelling the mechanisms behind mixed catalysts for the high yield production of single-walled carbon nanotubes.

    PubMed

    Tetali, Sailaja; Zaka, Mujtaba; Schönfelder, Ronny; Bachmatiuk, Alicja; Börrnert, Felix; Ibrahim, Imad; Lin, Jarrn H; Cuniberti, Gianaurelio; Warner, Jamie H; Büchner, Bernd; Rümmeli, Mark H

    2009-12-22

    The use of mixed catalysts for the high-yield production of single-walled carbon nanotubes is well-known. The mechanisms behind the improved yield are poorly understood. In this study, we systematically explore different catalyst combinations from Ni, Co, and Mo for the synthesis of carbon nanotubes via laser evaporation. Our findings reveal that the mixing of catalysts alters the catalyst cluster size distribution, maximizing the clusters' potential to form a hemispherical cap at nucleation and, hence, form a single-walled carbon nanotube. This process significantly improves the single-walled carbon nanotube yields.

  19. Surprising synthesis of nanodiamond from single-walled carbon nanotubes by the spark plasma sintering process

    NASA Astrophysics Data System (ADS)

    Mirzaei, Ali; Ham, Heon; Na, Han Gil; Kwon, Yong Jung; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Park, No-Hyung; Kang, Inpil; Kim, Hyoun Woo

    2016-10-01

    Nanodiamond (ND) was successfully synthesized using single-walled carbon nanotubes (SWCNTs) as a pure solid carbon source by means of a spark plasma sintering process. Raman spectra and X-ray diffraction patterns revealed the generation of the cubic diamond phase by means of the SPS process. Lattice-resolved TEM images confirmed that diamond nanoparticles with a diameter of about ˜10 nm existed in the products. The NDs were generated mainly through the gas-phase nucleation of carbon atoms evaporated from the SWCNTs. [Figure not available: see fulltext.

  20. Computational study on structural modification of single-walled carbon nanotubes by electron irradiation

    SciTech Connect

    Yasuda, Masaaki; Mimura, Ryosuke; Kawata, Hiroaki; Hirai, Yoshihiko

    2011-03-01

    Molecular dynamics simulation is carried out to investigate structural modifications of single-walled carbon nanotubes by electron irradiation. Electron irradiation effects are introduced by the Monte Carlo method using an elastic collision cross section. We demonstrate the applicability of the method to the analysis of structural modifications with electron beam such as cutting, shrinking, and bending. The behavior of the carbon atoms in the nanotube during the structural modification is revealed. The simulation results also show the variation of the mechanical properties of carbon nanotubes by electron irradiation.

  1. Sonication mediated covalent cross-linking of DNA to single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Dolash, Bridget D.; Lahiji, Roya R.; Zemlyanov, Dmitry Y.; Drachev, Vladimir P.; Reifenberger, Ronald; Bergstrom, Donald E.

    2013-02-01

    Sonication with nucleic acids has become a standard method for obtaining aqueous dispersions of carbon nanotubes. On the basis of theoretical studies and scanning probe microscopy (SPM) imaging a widely accepted model for DNA association with SWCNT is one in which the DNA binds through non-covalent π-stacking and hydrophobic interactions. Following the standard procedures established by others to prepare DNA associated single-wall carbon nanotubes (SWCNT), we have determined that sonication generates radical intermediates then form covalent anchors between the DNA and SWCNT. In light of this finding, results from studies on DNA associated carbon nanotubes, need to be more carefully interpreted.

  2. Nano-Plasticity of Single-Wall Carbon Nanotubes Under Uniaxial Compression

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Menon, Madu; Cho, Kyeongjae

    1999-01-01

    Nano-plasticity of thin single-wall carbon nanotubes under uniaxial compression is investigated through generalized tight-binding molecular dynamics (GTBMD) and ab-initio electronic structure methods. A novel mechanism of nano-plasticity of carbon nanotubes under uniaxial compression is observed in which bonding geometry collapses from a graphitic (sp(sup 2)) to a localized diamond like (sp(sup 3)) reconstruction. The computed critical stress (approximately equals 153 G Pa) and the shape of the resulting plastic deformation is in good agreement with recent experimental observation of collapse and fracture of compressed carbon nanotubes in polymer composites.

  3. Transmission electron microscope imaging of single-walled carbon nanotube interactions and mechanics on nitride grids

    NASA Astrophysics Data System (ADS)

    Abrams, Z. R.; Lereah, Y.; Hanein, Y.

    2006-09-01

    A method for analysing systems of isolated single-walled carbon nanotubes is of paramount importance if their structural characteristics are to be fully understood and utilized. Here we offer a simple technique for analysing such systems, with unprecedented contrast, using transmission electron microscope imaging of carbon nanotubes suspended over large holes in a silicon nitride grid. The nanotubes are grown directly on the viewing grids, using the chemical vapour deposition process, thus avoiding the use of chemicals or aggressive treatments. This method is simultaneously non-invasive, reusable, allows the analysis of multiple structures based on carbon nanotubes and is quickly implemented.

  4. Selective synthesis and device applications of semiconducting single-walled carbon nanotubes using isopropyl alcohol as feedstock.

    PubMed

    Che, Yuchi; Wang, Chuan; Liu, Jia; Liu, Bilu; Lin, Xue; Parker, Jason; Beasley, Cara; Wong, H-S Philip; Zhou, Chongwu

    2012-08-28

    The development of guided chemical vapor deposition (CVD) growth of single-walled carbon nanotubes provides a great platform for wafer-scale integration of aligned nanotubes into circuits and functional electronic systems. However, the coexistence of metallic and semiconducting nanotubes is still a major obstacle for the development of carbon-nanotube-based nanoelectronics. To address this problem, we have developed a method to obtain predominantly semiconducting nanotubes from direct CVD growth. By using isopropyl alcohol (IPA) as the carbon feedstock, a semiconducting nanotube purity of above 90% is achieved, which is unambiguously confirmed by both electrical and micro-Raman measurements. Mass spectrometric study was performed to elucidate the underlying chemical mechanism. Furthermore, high performance thin-film transistors with an on/off ratio above 10(4) and mobility up to 116 cm(2)/(V·s) have been achieved using the IPA-synthesized nanotube networks grown on silicon substrate. The method reported in this contribution is easy to operate and the results are highly reproducible. Therefore, such semiconducting predominated single-walled carbon nanotubes could serve as an important building block for future practical and scalable carbon nanotube electronics.

  5. Exposure to carbon nanotube material: aerosol release during the handling of unrefined single-walled carbon nanotube material.

    PubMed

    Maynard, Andrew D; Baron, Paul A; Foley, Michael; Shvedova, Anna A; Kisin, Elena R; Castranova, Vincent

    2004-01-09

    Carbon nanotubes represent a relatively recently discovered allotrope of carbon that exhibits unique properties. While commercial interest in the material is leading to the development of mass production and handling facilities, little is known of the risk associated with exposure. In a two-part study, preliminary investigations have been carried out into the potential exposure routes and toxicity of single-walled carbon nanotube material (SWCNT)--a specific form of the allotrope. The material is characterized by bundles of fibrous carbon molecules that may be a few nanometers in diameter, but micrometers in length. The two production processes investigated use-transition metal catalysts, leading to the inclusion of nanometer-scale metallic particles within unrefined SWCNT material. A laboratory-based study was undertaken to evaluate the physical nature of the aerosol formed from SWCNT during mechanical agitation. This was complemented by a field study in which airborne and dermal exposure to SWCNT was investigated while handling unrefined material. Although laboratory studies indicated that with sufficient agitation, unrefined SWCNT material can release fine particles into the air, concentrations generated while handling material in the field were very low. Estimates of the airborne concentration of nanotube material generated during handling suggest that concentrations were lower than 53 microg/m(3) in all cases. Glove deposits of SWCNT during handling were estimated at between 0.2 mg and 6 mg per hand.

  6. Control of the Diameter and Chiral Angle Distributions during Production of Single-wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel; Holmes, William; Sosa, Edward; Boul, Peter; Arepalli, Sivaram; Yowell, Leonard

    2008-01-01

    Many applications of single wall carbon nanotubes (SWCNT), especially in microelectronics, will benefit from use of certain (n,m) nanotube types (metallic, small gap semiconductor, etc.). However, as produced SWCNT samples are polydispersed, with many (n,m) types present and typical approximate 1:2 metal/semiconductor ratio. It has been recognized that production of SWCNTs with narrow 'tube type populations' is beneficial for their use in applications, as well as for the subsequent sorting efforts. In the present work, SWCNTs were produced by a pulsed laser vaporization (PLV) technique. The nanotube type populations were studied with respect to the production temperature with two catalyst compositions: Co/Ni and Rh/Pd. The nanotube type populations were measured via photoluminescence, UV-Vis-NIR absorption and Raman spectroscopy. It was found that in the case of Co/Ni catalyst, decreased production temperature leads to smaller average diameter, exceptionally narrow diameter distribution, and strong preference toward (8,7) nanotubes. The other nanotubes present are distributed evenly in the 7-30 deg chiral angle range. In the case of Rh/Pd catalyst, a decrease in the temperature leads to a small decrease in the average diameter, with the chiral angle distribution skewed towards 30 o and a preference toward (7,6), (8,6) and (8,7) nanotubes. However, the diameter distribution remains rather broad. These results demonstrate that PLV production technique can provide at least partial control over the nanotube (n,m) populations. In addition, these results have implications for the understanding the nanotube nucleation mechanism in the laser oven.

  7. Magnetic field asymmetry and high temperature magnetoresistance in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cobden, David

    2006-03-01

    The length scales and scattering processes in the one-dimensional electron system in single-walled carbon nanotubes remain only partially understood. Measuring the magnetoresistance, in both linear and nonlinear response, is a way to investigate these processes. In disordered nanotubes with ballistic paths much shorter than the length, we observe magnetoresistance in the metallic regime which at low temperatures resembles the universal fluctuations and weak localization seen in higher dimensional metals. A parabolic magnetoresistance persists at room temperature, indicating a significant role for phase coherence and/or interactions at high temperatures. While the linear resistance of a two-terminal sample must be an even function of magnetic field B by Onsager's principle, the nonlinear resistance need not be. Importantly, the B-asymmetric nonlinear terms can in principle be used to infer the strength of electron-electron interactions in the sample [1]. We have therefore also measured in detail the lowest order B-asymmetric current contributions, with a focus on the B-linear term. This has apparently not been done before in any system. Consistent with general theory, at high temperatures the term is small and has a constant sign independent of Fermi energy. At low temperatures it grows and develops mesoscopic fluctuations. Although these result imply that interactions are involved in the transport, calculations specific to nanotubes are needed in order to extract interaction parameters. This work was done by the authors of Ref [2]. References: [1] E.L. Ivchenko and B. Spivak, Phys. Rev. B 66, 155404 (2002); [2] Jiang Wei, Michael Shimogawa, Zenghui Wang, Iuliana Radu, Robert Dormaier, and David H. Cobden, Phys. Rev. Lett. (Dec. 2005) (cond-mat/0506275).

  8. AC field-induced polymer electroluminescence with single wall carbon nanotubes.

    PubMed

    Sung, Jinwoo; Choi, Yeon Sik; Kang, Seok Ju; Cho, Sung Hwan; Lee, Tae-Woo; Park, Cheolmin

    2011-03-09

    We developed a high-performance field-induced polymer electroluminescence (FPEL) device consisting of four stacked layers: a top metal electrode/thin solution-processed nanocomposite film of single wall carbon nanotubes (SWNTs) and a fluorescent polymer/insulator/transparent bottom electrode working under an alternating current (AC) electric field. A small amount of SWNTs that were highly dispersed in the fluorescent polymer matrix by a conjugate block copolymer dispersant significantly enhanced EL, and we were able to realize an SWNT-FPEL device with a light emission of approximately 350 cd/m(2) at an applied voltage of ±25 V and an AC frequency of 300 kHz. The brightness of the SWNT-FPEL device is much greater than those of other AC-based organic or even inorganic ELs that generally require at least a few hundred volts. Light is emitted from our SWNT-FPEL device because of the sequential injection of field-induced holes and then electron carriers through ambipolar carbon nanotubes under an AC field, followed by exciton formation in the conjugated organic layer. Field-induced bipolar charge injection provides great material design freedom for our devices; the energy level does not have to be aligned between the electrode and the emission layer, and the balance of the carrier injected and transported can be altered in contrast to that in conventional organic light-emitting diodes, leading to an extremely cost-effective and unified device architecture that is applicable to all red-green-blue fluorescent polymers.

  9. Electrochemical determination of cadmium and lead on pristine single-walled carbon nanotube electrodes.

    PubMed

    Bui, Minh-Phuong Ngoc; Li, Cheng Ai; Han, Kwi Nam; Pham, Xuan-Hung; Seong, Gi Hun

    2012-01-01

    A flexible, transparent, single-walled carbon nanotube (SWCNT) film electrode was prepared by vacuum filtering methods, followed by photolithographic patterning of a photoresist polymer on the SWCNT surface. The morphology of the SWCNT film electrode surface was characterized using a field-emission scanning electron microscope coupled to an energy-dispersive X-ray spectrophotometer. The electrodes were successfully used as a mercury-free electrochemical sensor for individual and simultaneous detection of cadmium (Cd(2+)) and lead (Pb(2+)) in 0.02 M HCl by square-wave stripping voltammetry. Some important operational parameters, including deposition time, deposition potential, square-wave amplitude, and square wave-frequency were optimized for the detection of Cd(2+) and Pb(2+). The newly developed sensor showed good linear behavior in the examined concentration. For individual Cd(2+) and Pb(2+) ion detection, the linear range was found from 0.033 to 0.228 ppm with detection limits of 0.7 ppb (R(2) = 0.985) for Cd(2+) and 0.8 ppb (R(2) = 0.999) for Pb(2+). For simultaneous detection, the linear range was found from 0.033 to 0.280 ppm with a limit of detection of 2.2 ppb (R(2) = 0.976) and 0.6 ppb (R(2) = 0.996) for Cd(2+) and Pb(2+), respectively. SWCNT film electrodes offered favorable reproducibility of ± 5.4% and 4.3% for Cd(2+) and Pb(2+), respectively. The experiments demonstrated the applicability of carbon nanotubes, specifically in the preparation of SWCNT films. The results suggest that the proposed flexible SWCNT film electrodes can be applied as simple, efficient, cost-effective, and/or disposable electrodes for simultaneous detection of heavy metal ions.

  10. Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Blancon, Jean-Christophe; Paillet, Matthieu; Tran, Huy Nam; Than, Xuan Tinh; Guebrou, Samuel Aberra; Ayari, Anthony; Miguel, Alfonso San; Phan, Ngoc-Minh; Zahab, Ahmed-Azmi; Sauvajol, Jean-Louis; Fatti, Natalia Del; Vallée, Fabrice

    2013-09-01

    The optical properties of single-wall carbon nanotubes are very promising for developing novel opto-electronic components and sensors with applications in many fields. Despite numerous studies performed using photoluminescence or Raman and Rayleigh scattering, knowledge of their optical response is still partial. Here we determine using spatial modulation spectroscopy, over a broad optical spectral range, the spectrum and amplitude of the absorption cross-section of individual semiconducting single-wall carbon nanotubes. These quantitative measurements permit determination of the oscillator strength of the different excitonic resonances and their dependencies on the excitonic transition and type of semiconducting nanotube. A non-resonant background is also identified and its cross-section comparable to the ideal graphene optical absorbance. Furthermore, investigation of the same single-wall nanotube either free standing or lying on a substrate shows large broadening of the excitonic resonances with increase of oscillator strength, as well as stark weakening of polarization-dependent antenna effects, due to nanotube-substrate interaction.

  11. Aharonov-Bohm interference and beating in single-walled carbon-nanotube interferometers.

    PubMed

    Cao, Jien; Wang, Qian; Rolandi, Marco; Dai, Hongjie

    2004-11-19

    Relatively low magnetic fields applied parallel to the axis of a chiral single-walled carbon nanotube are found causing large modulations to the p channel or valence band conductance of the nanotube in the Fabry-Perot interference regime. Beating in the Aharonov-Bohm type of interference between two field-induced nondegenerate subbands of spiraling electrons is responsible for the observed modulation with a pseudoperiod much smaller than that needed to reach the flux quantum Phi0 = h/e through the nanotube cross section. We show that single-walled nanotubes represent the smallest cylinders exhibiting the Aharonov-Bohm effect with rich interference and beating phenomena arising from well-defined molecular orbitals reflective of the nanotube chirality.

  12. Thin single-wall BN-nanotubes formed inside carbon nanotubes.

    PubMed

    Nakanishi, Ryo; Kitaura, Ryo; Warner, Jamie H; Yamamoto, Yuta; Arai, Shigeo; Miyata, Yasumitsu; Shinohara, Hisanori

    2013-01-01

    We report a high yield synthesis of single-wall boron nitride nanotubes (SWBNNTs) inside single-wall carbon nanotubes (SWCNTs), a nano-templated reaction, using ammonia borane complexes (ABC) as a precursor. Transmission electron microscope (TEM), high angle annular dark field (HAADF)-scanning TEM (STEM), electron energy loss spectra (EELS) and high resolution EELS mapping using aberration-corrected TEM system clearly show the formation of thin SWBNNTs inside SWCNTs. We have found that the yield of the SWBNNT formation is high and that the most of ABC molecules decompose and fuse to form the thin BNNTs at a temperature of 1,673 K having a narrow diameter distribution of 0.7 ± 0.1 nm. Optical absorption measurements suggest that the band gap of the thin SWBNNTs is about 6.0 eV, which provide the ideal insulator nanotubes with very small diameters.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  14. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors arrays

    SciTech Connect

    Seo, M.; Kim, H.; Kim, Y. H.; Yun, H.; McAllister, K.; Lee, S. W.; Na, J.; Kim, G. T.; Lee, B. J.; Kim, J. J.; Jeong, G. H.; Lee, I.; Kim, K. S.

    2015-07-20

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode patterns on top of the aligned SWNT along one direction. Both single and multi layer graphene were used for the electrode materials; typical p-type transistor and Schottky diode behavior were observed, respectively. Based on our fabrication method and device performances, several issues are suggested and discussed to improve the device reliability and finally to realize all carbon based future electronic systems.

  15. Thin film transistors of single-walled carbon nanotubes grown directly on glass substrates.

    PubMed

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

    2007-12-12

    We report a transistor of randomly networked single-walled carbon nanotubes on a glass substrate. The carbon nanotube networks acting as the active components of the thin film transistor were selectively formed on the transistor channel areas that were previously patterned with catalysts to avoid the etching process for isolating nanotubes. The nanotube density was more than 50 microm(-2), which is much larger than the percolation threshold. Transistors were successfully fabricated with a conducting and transparent ZnO for the back-side gate and the top-side gate. This allows the transparent electronics or suggests thin film applications of nanotubes for future opto-electronics.

  16. Effective permittivity of single-walled carbon nanotube composites: Two-fluid model

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin; Zangeneh, Hamid Reza; Moghadam, Firoozeh Karimi

    2015-12-01

    We develop an effective medium theory to obtain effective permittivity of a composite of two-dimensional (2D) aligned single-walled carbon nanotubes. Electronic excitations on each nanotube surface are modeled by an infinitesimally thin layer of a 2D electron gas represented by two interacting fluids, which takes into account different nature of the σ and π electrons. Calculations of both real and imaginary parts of the effective dielectric function of the system are presented, for different values of the filling factor and radius of carbon nanotubes.

  17. Effective permittivity of single-walled carbon nanotube composites: Two-fluid model

    SciTech Connect

    Moradi, Afshin; Zangeneh, Hamid Reza; Moghadam, Firoozeh Karimi

    2015-12-15

    We develop an effective medium theory to obtain effective permittivity of a composite of two-dimensional (2D) aligned single-walled carbon nanotubes. Electronic excitations on each nanotube surface are modeled by an infinitesimally thin layer of a 2D electron gas represented by two interacting fluids, which takes into account different nature of the σ and π electrons. Calculations of both real and imaginary parts of the effective dielectric function of the system are presented, for different values of the filling factor and radius of carbon nanotubes.

  18. Boron and Nitrogen Doped Single walled Carbon Nanotubes as Possible Dilute Magnetic Semiconductors

    PubMed Central

    2007-01-01

    The structure of single walled armchair and zig-zag carbon nanotubes having 70 atoms and two carbons replaced by boron or nitrogen is obtained at minium energy using HF/6-31G* molecular orbital theory. The calculations show that the ground state of the zig-zag tubes is a triplet state while for the armchair tubes it is a singlet. In the zig-zag tubes the density of states at the Fermi level is greater for the spin down states compared to the spin up state indicating that the doped tubes could be ferromagnetic.

  19. Advances in NO2 sensing with individual single-walled carbon nanotube transistors.

    PubMed

    Chikkadi, Kiran; Muoth, Matthias; Roman, Cosmin; Haluska, Miroslav; Hierold, Christofer

    2014-01-01

    The charge carrier transport in carbon nanotubes is highly sensitive to certain molecules attached to their surface. This property has generated interest for their application in sensing gases, chemicals and biomolecules. With over a decade of research, a clearer picture of the interactions between the carbon nanotube and its surroundings has been achieved. In this review, we intend to summarize the current knowledge on this topic, focusing not only on the effect of adsorbates but also the effect of dielectric charge traps on the electrical transport in single-walled carbon nanotube transistors that are to be used in sensing applications. Recently, contact-passivated, open-channel individual single-walled carbon nanotube field-effect transistors have been shown to be operational at room temperature with ultra-low power consumption. Sensor recovery within minutes through UV illumination or self-heating has been shown. Improvements in fabrication processes aimed at reducing the impact of charge traps have reduced the hysteresis, drift and low-frequency noise in carbon nanotube transistors. While open challenges such as large-scale fabrication, selectivity tuning and noise reduction still remain, these results demonstrate considerable progress in transforming the promise of carbon nanotube properties into functional ultra-low power, highly sensitive gas sensors.

  20. Impact of synthesis methods on the transport of single walled carbon nanotubes in the aquatic environment.

    PubMed

    Chowdhury, Indranil; Duch, Mathew C; Gits, Colton C; Hersam, Mark C; Walker, Sharon L

    2012-11-06

    In this study, a systematic approach has been followed to investigate the fate and transport of single walled carbon nanotubes (SWCNTs) from synthesis to environmentally relevant conditions. Three widely used SWCNT synthesis methods have been investigated in this study including high pressure carbon monoxide (HiPco), SWeNT CoMoCat, and electric arc discharge technique (EA). This study relates the transport of three SWCNTs (HiPco-D, SG65-D, and P2-D) with different synthesis methods and residual catalyst content revealing their influence on the subsequent fate of the nanotubes. To minimize nanotube bundling and aggregation, the SWCNTs were dispersed using the biocompatible triblock copolymer Pluronic, which allowed the comparison in the transport trends among these SWCNTs. After purification, the residual metal catalyst between the SWCNTs follows the trend: HiPco-D > SG65-D > P2-D. The electrophoretic mobility (EPM) and hydrodynamic diameter of SWCNTs remained insensitive to SWCNT type, pH, and presence of natural organic matter (NOM); but were affected by ionic strength (IS) and ion valence (K(+), Ca(2+)). In monovalent ions, the hydrodynamic diameter of SWCNTs was not influenced by IS, whereas larger aggregation was observed for HiPco-D with IS than P2-D and SG65-D in the presence of Ca(2+). Transport of HiPco-D in the porous media was significantly higher than SG65-D followed by P2-D. Release of HiPco-D from porous media was higher than SG65-D followed by P2-D, though negligible amount of all types of SWCNTs (<5%) was released. Both transport and release patterns follow a similar trend to what was observed for residual metal catalysts in SWCNTs. Addition of NOM increased the transport of all SWCNTs primarily due to electrosteric repulsion. HiPco-D was notably more acidic than SG65-D followed by P2-D, which is similar to the transport trend. Overall, it was observed that the synthesis methods resulted in distinctive breakthrough trends, which were correlated to

  1. Formation and growth mechanisms of single-walled metal oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Yucelen, Gulfem Ipek

    In this thesis, main objectives are to discover the first molecular-level mechanistic framework governing the formation and growth of single-walled metal-oxide nanotubes, apply this framework to demonstrate the engineering of nanotubular materials of controlled dimensions, and to progress towards a quantitative multiscale understanding of nanotube formation. In Chapter 2, the identification and elucidation of the mechanistic role of molecular precursors and nanoscale (1-3 nm) intermediates with intrinsic curvature, in the formation of single-walled aluminosilicate nanotubes is reported. The structural and compositional evolution of molecular and nanoscale species over a length scale of 0.1-100 nm, are characterized by electrospray ionization (ESI) mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy. DFT calculations revealed the intrinsic curvature of nanoscale intermediates with bonding environments similar to the structure of the final nanotube product. It is shown that curved nano-intermediates form in aqueous synthesis solutions immediately after initial hydrolysis of reactants at 25 °C, disappear from the solution upon heating to 95 °C due to condensation, and finally rearrange to form ordered single-walled aluminosilicate nanotubes. Integration of all results leads to the construction of the first molecular-level mechanism of single-walled metal oxide nanotube formation, incorporating the role of monomeric and polymeric aluminosilicate species as well as larger nanoparticles. Then, in Chapter 3, new molecular-level concepts for constructing nanoscopic metal oxide objects are demonstrated. The diameters of metal oxide nanotubes are shaped with Angstrom-level precision by controlling the shape of nanometer-scale precursors. The subtle relationships between precursor shape and structure and final nanotube curvature are measured (at the molecular level). Anionic ligands (both organic and inorganic) are used to exert fine control over precursor

  2. Carbon nanotunnels form from single-walled carbon nanotubes interacting with a diamond (100)-(2 X 1) surface.

    SciTech Connect

    Horner, D. A.; Sternberg, M.; Zapol, P.; Curtiss, L. A.

    2011-08-01

    A quantum chemical study of the interaction of (5,5), (7,7), (9,9) and (8,0) single-walled carbon nanotubes with a clean (100)-(2 x 1) diamond surface is reported. Stable structures with covalent bonds at the interface were found for carbon nanotubes oriented parallel or perpendicular to the dimer rows on the reconstructed (100) surface. The binding energy of the most stable (5,5) nanotube-diamond structure is 1.7 eV/{angstrom}, and is attributed to strong covalent bonds formed between the carbon nanotube and the diamond surface. The structure of the nanotube is distorted by adsorption on the surface such that it adopts a tunnel-like geometry. Two other nanotunnel geometries were found for the (5,5) nanotube, with binding energies of 1.39 and 1.09 eV/{angstrom}. In the most stable (5,5) nanotube-diamond structure the interaction between the nanotube and the diamond surface produces a 0.6 eV band gap near the Fermi level, but the metallic character of the nanotube is maintained in the two other, less strongly bound nanotunnel structures. No charge transfer occurs between the diamond surface and the nanotunnels in any of the three orientations. Binding energies decrease with increases in tube diameter, to the extent that one of the three nanotunnel structures is not formed by (9,9) carbon nanotubes.

  3. Purification of semiconducting single-walled carbon nanotubes by spiral counter-current chromatography.

    PubMed

    Knight, Martha; Lazo-Portugal, Rodrigo; Ahn, Saeyoung Nate; Stefansson, Steingrimur

    2017-02-03

    Over the last decade man-made carbon nanostructures have shown great promise in electronic applications, but they are produced as very heterogeneous mixtures with different properties so the achievement of a significant commercial application has been elusive. The dimensions of single-wall carbon nanotubes are generally a nanometer wide, up to hundreds of microns long and the carbon nanotubes have anisotropic structures. They are processed to have shorter lengths but they need to be sorted by diameter and chirality. Thus counter-current chromatography methods developed for large molecules are applied to separate these compounds. A modified mixer-settler spiral CCC rotor made with 3 D printed disks was used with a polyethylene glycol-dextran 2-phase solvent system and a surfactant gradient to purify the major species in a commercial preparation. We isolated the semi-conducting single walled carbon nanotube chiral species identified by UV spectral analysis. The further development of spiral counter-current chromatography instrumentation and methods will enable the scalable purification of carbon nanotubes useful for the next generation electronics.

  4. Capacitive tunnels in single-walled carbon nanotube networks on flexible substrate

    NASA Astrophysics Data System (ADS)

    Iqbal, M. Z.; Iqbal, M. W.; Eom, Jonghwa; Ahmad, Muneer; Ferrer-Anglada, Núria

    2012-03-01

    We report the analysis of single-walled carbon nanotube networks, which are expected to be suitable as miniaturized flexible radio frequency RC filters and also have important implications for high frequency devices. The surface morphology obtained by atomic force microscopy shows that most of the growth on polypropylene carbonate substrate is homogeneous. The large value of peak intensity ratio of G and D band in Raman spectra indicates the high purity network. Nyquist plots of carbon nanotube networks on a flexible substrate are close to real circles, indicating that the material is conducting, and suggest a simple equivalent circuit having a resistor in parallel with a capacitor. The Bode plots give the dependence of real and imaginary impedances on frequency. While at high frequency, the impedance decreases, due to generation of capacitance between a single-walled carbon nanotube; at low frequency, it shows the normal behavior, having constant value. The tunnels among different carbon nanotubes are capable of storing electric charge. The accumulative capacitances of tunnels for three varied concentrations are calculated by electrochemical impedance spectroscopy simulations to fit the observed Nyquist plots.

  5. G-band resonant Raman study of 62 isolated single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jorio, A.; Souza Filho, A. G.; Dresselhaus, G.; Dresselhaus, M. S.; Swan, A. K.; Ünlü, M. S.; Goldberg, B. B.; Pimenta, M. A.; Hafner, J. H.; Lieber, C. M.; Saito, R.

    2002-04-01

    We report G-band resonance Raman spectra of single-wall carbon nanotubes (SWNTs) at the single-nanotube level. By measuring 62 different isolated SWNTs resonant with the incident laser, and having diameters dt ranging between 0.95 nm and 2.62 nm, we have conclusively determined the dependence of the two most intense G-band features on the nanotube structure. The higher-frequency peak is not diameter dependent (ω+G=1591 cm-1), while the lower-frequency peak is given by ω-G=ω+G-C/d2t, with C being different for metallic and semiconducting SWNTs (CM>CS). The peak frequencies do not depend on nanotube chiral angle. The intensity ratio between the two most intense features is in the range 0.1

  6. Sequence-independent helical wrapping of single-walled carbon nanotubes by long genomic DNA.

    PubMed

    Gigliotti, Brittany; Sakizzie, Brenda; Bethune, Donald S; Shelby, Robert M; Cha, Jennifer N

    2006-02-01

    Because of their nanometer sizes and molecular recognition capabilities, biological systems have garnered much attention as vehicles for the directed assembly of nanoscale materials.(1-6) One of the greatest challenges of this research has been to successfully interface biological systems with electronic materials, such as semiconductors and metals. As a means to address some of these issues, Sarikaya, Belcher, and others have used a combinatorial technique called phage display(7-9) to discover new families of peptides that showed binding affinities to various substrates. More recently, Zheng and co-workers used combinatorial DNA libraries to isolate short DNA oligomers (30-90 bases) that could disperse single-walled carbon nanotubes (SWCNT) in water.(10) Through a systematic analysis, they found that short oligonucleotides having repeating sequences of gunanines and thymines (dGdT)(n) could wrap in a helical manner around a CNT with periodic pitch.(11) Although helix formation around SWCNTs having regular pitches is an effective method for dispersing and separating CNTs, the need for specific repeating sequences limits use to non-natural DNA that must be synthesized with optimal lengths of less than 150 bases. In contrast, we demonstrate here that long genomic single-stranded DNA (>100 bases) of a completely random sequence of bases can be used to disperse CNTs efficiently through the single-stranded DNA's (ssDNA) ability to form tight helices around the CNTs with distinct periodic pitches. Although this process occurs irrespective of the DNA sequence, we show that this process is highly dependent on the removal of complementary strands. We also demonstrate that although the helix pitch-to-pitch distances remain constant down the length of a single CNT, the distances are variable from one DNA-CNT to another. Finally, we report initial work that shows that methods developed to align long dsDNA can be applied in a similar fashion to produce highly dense arrays of

  7. Modulation of energy/electron transfer in gold nanoclusters by single walled carbon nanotubes and further consequences.

    PubMed

    Das, Tarasankar; Maity, Arnab; Mondal, Somen; Purkayastha, Pradipta

    2015-04-15

    Semiconductor or metallic character in single-walled carbon nanotubes (SWCNTs) is developed because of their chirality and diameter. Depending upon the extent of these characters in a particular sample of SWCNT, various electronic and mechanical applications are formulated. In this work we used protein protected red emitting gold nanoclusters (AuNCs) to enhance the metallic character in SWCNTs through electron transfer induced by photonic excitation. The AuNCs have been synthesized following a known protocol that generates Au(+) protected Au(0) clusters. Normal and carboxylic acid functionalized SWCNTs were obtained commercially for usage in the experiments. The non-functionalized SWCNTs facilitate intersystem electron transfer while the functionalized ones defer the phenomenon, which, in turn, affects the metallic character in the nanotubes. Steady state and time resolved fluorescence spectroscopy prove the dynamics and electrochemistry supports the intersystem electron transfer process.

  8. Modulation of energy/electron transfer in gold nanoclusters by single walled carbon nanotubes and further consequences

    NASA Astrophysics Data System (ADS)

    Das, Tarasankar; Maity, Arnab; Mondal, Somen; Purkayastha, Pradipta

    2015-04-01

    Semiconductor or metallic character in single-walled carbon nanotubes (SWCNTs) is developed because of their chirality and diameter. Depending upon the extent of these characters in a particular sample of SWCNT, various electronic and mechanical applications are formulated. In this work we used protein protected red emitting gold nanoclusters (AuNCs) to enhance the metallic character in SWCNTs through electron transfer induced by photonic excitation. The AuNCs have been synthesized following a known protocol that generates Au+ protected Au0 clusters. Normal and carboxylic acid functionalized SWCNTs were obtained commercially for usage in the experiments. The non-functionalized SWCNTs facilitate intersystem electron transfer while the functionalized ones defer the phenomenon, which, in turn, affects the metallic character in the nanotubes. Steady state and time resolved fluorescence spectroscopy prove the dynamics and electrochemistry supports the intersystem electron transfer process.

  9. Formation of single-walled carbon nanotube thin films enriched with semiconducting nanotubes and their application in photoelectrochemical devices.

    PubMed

    Wei, Li; Tezuka, Noriyasu; Umeyama, Tomokazu; Imahori, Hiroshi; Chen, Yuan

    2011-04-01

    Single-walled carbon nanotube (SWCNT) thin films, containing a high-density of semiconducting nanotubes, were obtained by a gel-centrifugation method. The agarose gel concentration and centrifugation force were optimized to achieve high semiconducting and metallic nanotube separation efficiency at 0.1 wt% agarose gel and 18,000g. The thickness of SWCNT films can be precisely controlled from 65 to 260 nm with adjustable transparency. These SWCNT films were applied in photoelectrochemical devices. Photocurrents generated by semiconducting SWCNT enriched films are 15-35% higher than those by unsorted SWCNT films. This is because of reducing exciton recombination channels as a result of the removal of metallic nanotubes. Thinner films generate higher photocurrents because charge carriers have less chances going in metallic nanotubes for recombination, before they can reach electrodes. Developing more scalable and selective methods for high purity semiconducting SWCNTs is important to further improve the photocurrent generation efficiency by using SWCNT-based photoelectrochemical devices.

  10. Growth of horizontally aligned single-walled carbon nanotubes on anisotropically etched silicon substrate

    NASA Astrophysics Data System (ADS)

    Orofeo, Carlo M.; Ago, Hiroki; Ikuta, Tatsuya; Takahasi, Koji; Tsuji, Masaharu

    2010-09-01

    Directional controllability of single-walled carbon nanotubes (SWNTs) is an important issue for future nanoelectronics applications. For direct integration of carbon nanotubes with modern electronics, aligned growth of carbon nanotubes on SiO2/Si is desirable. We developed a new method to horizontally align SWNTs directly on SiO2/Si substrate by creating trenches on Si(100) through anisotropic etching followed by thermal oxidation. The V-shaped trenches highly improved the alignment of SWNTs and the degree of alignment is comparable to the step-templated alignment of carbon nanotubes on crystals. The trenches also improved the density of aligned nanotubes due to the combination of ``trench-guided'' and gas-flow guided alignment. Our new insights on carbon nanotube alignment on SiO2/Si will greatly contribute to future large-scale nanoelectronic applications.Directional controllability of single-walled carbon nanotubes (SWNTs) is an important issue for future nanoelectronics applications. For direct integration of carbon nanotubes with modern electronics, aligned growth of carbon nanotubes on SiO2/Si is desirable. We developed a new method to horizontally align SWNTs directly on SiO2/Si substrate by creating trenches on Si(100) through anisotropic etching followed by thermal oxidation. The V-shaped trenches highly improved the alignment of SWNTs and the degree of alignment is comparable to the step-templated alignment of carbon nanotubes on crystals. The trenches also improved the density of aligned nanotubes due to the combination of ``trench-guided'' and gas-flow guided alignment. Our new insights on carbon nanotube alignment on SiO2/Si will greatly contribute to future large-scale nanoelectronic applications. Electronic supplementary information (ESI) available: SEM images of SWNTs grown under different CVD conditions. See DOI: 10.1039/c0nr00170h

  11. Photoinduced Spontaneous Free-Carrier Generation in Semiconducting Single-Walled Carbon Nanotubes

    DOE PAGES

    Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.; ...

    2015-11-04

    The strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. We found that the conditions of the microwave conductivity measurement allow us tomore » avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. At low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions.« less

  12. Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm

    PubMed Central

    Asghar, Waseem; Shafiee, Hadi; Velasco, Vanessa; Sah, Vasu R.; Guo, Shirui; El Assal, Rami; Inci, Fatih; Rajagopalan, Adhithi; Jahangir, Muntasir; Anchan, Raymond M.; Mutter, George L.; Ozkan, Mihrimah; Ozkan, Cengiz S.; Demirci, Utkan

    2016-01-01

    Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1–25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure. PMID:27538480

  13. Photoinduced Spontaneous Free-Carrier Generation in Semiconducting Single-Walled Carbon Nanotubes

    SciTech Connect

    Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.; Rumbles, Garry

    2015-11-04

    The strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. We found that the conditions of the microwave conductivity measurement allow us to avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. At low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions.

  14. Photoinduced spontaneous free-carrier generation in semiconducting single-walled carbon nanotubes

    PubMed Central

    Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.; Rumbles, Garry

    2015-01-01

    Strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. The conditions of the microwave conductivity measurement allow us to avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. Even at low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions. PMID:26531728

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm

    NASA Astrophysics Data System (ADS)

    Asghar, Waseem; Shafiee, Hadi; Velasco, Vanessa; Sah, Vasu R.; Guo, Shirui; El Assal, Rami; Inci, Fatih; Rajagopalan, Adhithi; Jahangir, Muntasir; Anchan, Raymond M.; Mutter, George L.; Ozkan, Mihrimah; Ozkan, Cengiz S.; Demirci, Utkan

    2016-08-01

    Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1–25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure.

  17. Chirality-Controlled Growth of Single-Wall Carbon Nanotubes Using Vapor Phase Epitaxy: Mechanistic Understanding and Scalable Production

    DTIC Science & Technology

    2016-09-15

    period, that is, growth plus termination, we assume the average growth rate (R̅t) of a (n, m) SWCNT at time t follows exponential kinetics ?̅?...AFRL-AFOSR-VA-TR-2016-0319 Chirality-Controlled Growth of Single-Wall Carbon Nanotubes Using Vapor Phase Epitaxy: Mechanistic Understanding and...controlled growth of single-wall carbon nanotubes using vapor phase epitaxy: mechanistic understanding and scalable production FA9550-14-1-0115 Zhou

  18. Organic/hybrid nanoparticles and single-walled carbon nanotubes: preparation methods and chiral applications.

    PubMed

    Alhassen, Haysem; Antony, Vijy; Ghanem, Ashraf; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Ostrikov, Kostya Ken

    2014-11-01

    Nanoparticles are molecular-sized solids with at least one dimension measuring between 1-100 nm or 10-1000 nm depending on the individual discipline's perspective. They are aggregates of anywhere from a few hundreds to tens of thousands of atoms which render them larger than molecules but smaller than bulk solids. Consequently, they frequently exhibit physical and chemical properties somewhere between. On the other hand, nanocrystals are a special class of nanoparticles which have started gaining attention recently owing to their unique crystalline structures which provide a larger surface area and promising applications including chiral separations. Hybrid nanoparticles are supported by the growing interest of chemists, physicists, and biologists, who are researching to fully exploit them. These materials can be defined as molecular or nano-composites with mixed (organic or bio) and inorganic components, where at least one of the component domain has a dimension ranging from a few Å to several nanometers. Similarly, and due to their extraordinary physical, chemical, and electrical properties, single-walled carbon nanotubes have been the subject of intense research. In this short review, the focus is mainly on the current well-established simple preparation techniques of chiral organic and hybrid nanoparticles as well as single-walled carbon nanotubes and their applications in separation science. Of particular interest, cinchonidine, chitosan, and β-CD-modified gold nanoparticles (GNPs) are discussed as model examples for organic and hybrid nanoparticles. Likewise, the chemical vapor deposition method, used in the preparation of single-walled carbon nanotubes, is discussed. The enantioseparation applications of these model nanomaterials is also presented.

  19. Industrially synthesized single-walled carbon nanotubes: compositional data for users, environmental risk assessments, and source apportionment

    NASA Astrophysics Data System (ADS)

    Plata, D. L.; Gschwend, P. M.; Reddy, C. M.

    2008-05-01

    Commercially available single-walled carbon nanotubes (SWCNTs) contain large percentages of metal and carbonaceous impurities. These fractions influence the SWCNT physical properties and performance, yet their chemical compositions are not well defined. This lack of information also precludes accurate environmental risk assessments for specific SWCNT stocks, which emerging local legislation requires of nanomaterial manufacturers. To address these needs, we measured the elemental, molecular, and stable carbon isotope compositions of commercially available SWCNTs. As expected, catalytic metals occurred at per cent levels (1.3-29%), but purified materials also contained unexpected metals (e.g., Cu, Pb at 0.1-0.3 ppt). Nitrogen contents (up to 0.48%) were typically greater in arc-produced SWCNTs than in those derived from chemical vapor deposition. Toluene-extractable materials contributed less than 5% of the total mass of the SWCNTs. Internal standard losses during dichloromethane extractions suggested that metals are available for reductive dehalogenation reactions, ultimately resulting in the degradation of aromatic internal standards. The carbon isotope content of the extracted material suggested that SWCNTs acquired much of their carbonaceous contamination from their storage environment. Some of the SWCNTs, themselves, were highly depleted in 13C relative to petroleum-derived chemicals. The distinct carbon isotopic signatures and unique metal 'fingerprints' may be useful as environmental tracers allowing assessment of SWCNT sources to the environment.

  20. Human Airway Epithelial Cell Responses to Single Walled Carbon Nanotube Exposure: Nanorope-Residual Body Formation

    SciTech Connect

    Panessa-Warren, Barbara J.; Warren, John B.; Kisslinger, Kim; Crosson, Kenya; Maye, Mathew M.

    2012-11-01

    This investigation examines the 'first contact responses' of in vitro human epithelial airway cells exposed to unrefined single walled carbon nanotubes (SWCNTs) [containing metal catalyst, carbon black, amorphous carbon, graphitic shells, and SWCNTs], and refined acid/peroxide cleaned and cut SWCNTs at low and high dose exposures (0.16 ug/L and 1.60 ug/L) for 2, 3 and 3.5 hours. FTIR, X-ray compositional analysis, morphological TEM analysis and UV-Vis were used to physicochemically characterize the SWCNTs in this study. Following SWCNT exposure to human lung NCI-H292 epithelial monolayers, the airway cells were prepared for light microscopy vital staining, or fixed in glutaraldehyde for SEM/TEM imaging to determine SWCNT binding, uptake, intracellular processing and organellar/SWCNT fate within the exposure period. At 2 hr exposures to both unrefined Carbolex, and refined SWCNTs (at both high and low doses), there were no increases in lung cell necrosis compared to controls. However high dose, 3 hr exposures to unrefined Carbolex material produced severe cell damage (apical and basal plasma membrane holes, decreased mitochondria, numerous intracellular vesicles containing nanomaterial and membrane fragments) and increased cell necrosis. The refined SWCNTs exposed for 3 hr at low dose produced no increase in cell death, although high dose exposure produced significant cell death. By TEM, Acid/peroxide cleaned SWCNT 3 hr exposures at high and low doses, revealed SWCNTs attachment to cell surface mucin, and SWCNT uptake into the cells during membrane recycling. Membranes and SWCNTs were seen within cytoplasmic lamellar body-type vesicles, where vesicular contents were bio-degraded, eventually forming long SWCNT-nanoropes, which were subsequently released into the cytoplasm as clusters of attached nanoropes, as the vesicle membranes fragmented. These Nanorope-Residual Bodies did not cause damage to the surrounding organelles or cytoplasm, and seemed very stabile in the

  1. Unique aggregation of anthrax (Bacillus anthracis) spores by sugar-coated single-walled carbon nanotubes.

    PubMed

    Wang, Haifang; Gu, Lingrong; Lin, Yi; Lu, Fushen; Meziani, Mohammed J; Luo, Pengju G; Wang, Wei; Cao, Li; Sun, Ya-Ping

    2006-10-18

    There has been significant interest in the binding of anthrax spores by molecular species, but with only limited success. Proteins and more recently peptides were used. However, despite the known presence of carbohydrates on the spore surface, carbohydrate-carbohydrate interactions have hardly been explored likely because of the lack of required specific platform for synthetic carbohydrates. We report the successful use of single-walled carbon nanotubes as a truly unique scaffold for displaying multivalent monosaccharide ligands that bind effectively to anthrax spores with divalent cation mediation to cause significant spore aggregation. The work should have far-reaching implications in development of countermeasure technologies.

  2. Effects of ion beam heating on Raman spectra of single-walled carbon nanotubes

    SciTech Connect

    Hulman, Martin; Skakalova, Viera; Krasheninnikov, A. V.; Roth, S.

    2009-02-16

    Free standing films of single-wall carbon nanotubes were irradiated with energetic N{sup +} and C{sup 4+} ions. The observed changes in the Raman line shape of the radial breathing mode and the G band of the C{sup 4+} irradiated samples were similar to those found for a thermally annealed sample. We ascribe these changes to thermal desorption of volatile dopants from the initially doped nanotubes. A simple geometry of the experiment allows us to estimate the temperature rise by one-dimensional heat conductance equation. The calculation indicates that irradiation-mediated increase in temperature may account for the observed Raman spectra changes.

  3. Near-infrared fluorescent single walled carbon nanotube-chitosan composite: Interfacial strain transfer efficiency assessment

    NASA Astrophysics Data System (ADS)

    Mol Menamparambath, Mini; Arabale, Girish; Nikolaev, Pavel; Baik, Seunghyun; Arepalli, Sivaram

    2013-04-01

    Effective load transfer at the single walled carbon nanotube (SWCNT)-polymer interface is most desirable for mechanically reinforced polymer composites. Versatile layer-by-layer assembly technique achieved dispersion and uniform distribution of sodium carboxymethylcellulose (CMC)-solubilized SWCNTs within the polymer matrix. Electrostatic interaction between positively charged chitosan and negatively charged CMC facilitates design of an optically active biocompatible nanocomposite. Interfacial strain transfer efficiency of SWCNT-chitosan nanocomposite was assessed via SWCNT Raman and photoluminescence band shifts under uniaxial strain. Photoluminescence peak shift rates of individual semiconducting SWCNTs were investigated and compared with tight binding model calculations.

  4. Single wall carbon nanohorn as a drug carrier for controlled release

    NASA Astrophysics Data System (ADS)

    Xu, Jianxun; Yudasaka, Masako; Kouraba, Sachio; Sekido, Mitsuru; Yamamoto, Yuhei; Iijima, Sumio

    2008-08-01

    A single wall carbon nanohorn (SWNH) is a new kind of single-graphene tubules with a diameter of 2-5 nm and a length 40-50 nm. In this work, we used oxidized SWNH (SWNHox) to incorporate vancomycin hydrochloride (VCM) for its controlled release by taking advantage of the interactions between VCM and SWNHox. Phospholipid-poly(ethylene glycol) was used to modify the hydrophobic surface of SWNHox to improve its dispersion in aqueous systems. In the release study using this complex, a stable release of VCM was achieved for an extended period.

  5. Nanobioconjugates of Candida antarctica lipase B and single-walled carbon nanotubes in biodiesel production.

    PubMed

    Bencze, László Csaba; Bartha-Vári, Judith H; Katona, Gabriel; Toşa, Monica Ioana; Paizs, Csaba; Irimie, Florin-Dan

    2016-01-01

    Carboxylated single-walled carbon nanotubes (SWCNTCOOH) were used as support for covalent immobilization of Candida antarctica lipase B (CaL-B) using linkers with different lengths. The obtained nanostructured biocatalysts with low diffusional limitation were tested in batch mode in the ethanolysis of the sunflower oil. SWCNTCOOH-CaL-B proved to be a highly efficient and stable biocatalyst in acetonitrile (83.4% conversion after 4h at 35°C, retaining >90% of original activity after 10 cycles).

  6. Chemical vapor deposition of methane for single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kong, Jing; Cassell, Alan M.; Dai, Hongjie

    1998-08-01

    We report the synthesis of high-quality single-walled carbon nanotubes (SWNT) by chemical vapor deposition (CVD) of methane at 1000°C on supported Fe 2O 3 catalysts. The type of catalyst support is found to control the formation of individual or bundled SWNTs. Catalysts supported on crystalline alumina nanoparticles produce abundant individual SWNTs and small bundles. Catalysts supported by amorphous silica particles produce only SWNT bundles. Studies of the ends of SWNTs lead to an understanding of their growth mechanism. Also, we present the results of methane CVD on supported NiO, CoO and NiO/CoO catalysts.

  7. Water Soluble Single-Walled Carbon Nanotubes Inhibit Stimulated Endocytosis in Neurons

    PubMed Central

    Malarkey, Erik B.; Reyes, Reno C.; Zhao, Bin; Haddon, Robert C.; Parpura, Vladimir

    2009-01-01

    We report the use of chemically-functionalized water soluble single-walled carbon nanotube (SWNT) graft copolymers to inhibit endocytosis. The graft copolymers were prepared by the functionalization of SWNTs with poly-ethylene glycol. When added to the culturing medium, these functionalized water soluble SWNTs were able to increase the length of various neuronal processes, neurites, as previously reported. Here we have determined that SWNTs are able to block stimulated membrane endocytosis in neurons, which could then explain the previously noted extended neurite length. PMID:18759491

  8. The compressive buckling and size effect of single-walled carbon nanotubes

    SciTech Connect

    Sun, Yuzhou Zhu, Yanzhi; Li, Dongxia

    2015-03-10

    A higher-order Bernoulli-Euler beam model is developed to investigate the compressive buckling and size effect of single-walled carbon nanotubes by using a higher-order continuum relationship that has been previously proposed by the present authors. The second-order deformation gradients with respect to the axial direction are also considered, and the beam parameters are obtained by calculating the constitutive response around the circumference. The critical compressive force is analytically provided, and the size effect is studied by estimating the contribution of the higher-order terms.

  9. Influence of cysteine doping on photoluminescence intensity from semiconducting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kurnosov, N. V.; Leontiev, V. S.; Linnik, A. S.; Karachevtsev, V. A.

    2015-03-01

    Photoluminescence (PL) from semiconducting single-walled carbon nanotubes can be applied for detection of cysteine. It is shown that cysteine doping (from 10-8 to 10-3 M) into aqueous suspension of nanotubes with adsorbed DNA leads to increase of PL intensity. The PL intensity was enhanced by 27% at 10-3 M cysteine concentration in suspension. Most likely, the PL intensity increases due to the passivation of p-defects on the nanotube by the cysteine containing reactive thiol group. The effect of doping with other amino acids without this group (methionine, serine, aspartic acid, lysine, proline) on the PL intensity is essentially weaker.

  10. Package of double helical bromine chains inside single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yao, Zhen; Liu, Chun Jian; Lv, Hang; Yang, Xi Bao

    2016-10-01

    The helicity of stable double helical bromine chains inside single-walled carbon nanotubes (SWCNTs) was studied through the calculation of systematic interaction energy, using the van der Waals interaction potential. The results presented clear images of stable double helical structures inside SWCNTs. The optimal helical radius and helical angle of chain structure increase and decrease, respectively, with the increase of tube radius. The detailed analysis indicated that some metastable structures in SWCNTs may also co-exist with the optimal structures, but not within the same tubes. In addition, a detailed simulation of X-ray diffraction patterns was performed for the obtained optimal helical structures.

  11. Molecule-induced quantum confinement in single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hida, Akira; Ishibashi, Koji

    2015-04-01

    A method of fabricating quantum-confined structures with single-walled carbon nanotubes (SWNTs) has been developed. Scanning tunneling spectroscopy revealed that a parabolic confinement potential appeared when collagen model peptides were attached to both ends of an individual SWNT via the formation of carboxylic anhydrides. On the other hand, the confinement potential was markedly changed by yielding the peptide bonds between the SWNT and the collagen model peptides. Photoluminescence spectroscopy measurements showed that a type-II quantum dot was produced in the obtained heterostructure.

  12. Detecting the formation of single-walled carbon nanotube rings by photoabsorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hida, Akira; Suzuki, Takayuki; Ishibashi, Koji

    2016-08-01

    Photoabsorption spectroscopy was conducted on single-walled carbon nanotubes (SWNTs) during the formation of ring structures. The absorption bands observed before starting the formation gradually shifted while broadening in the middle. When they finally disappeared, it was found, via atomic force microscopy observations, that almost all SWNTs were transformed into rings. The spectral changes were assumed to be due to the changes in the electronic states of SWNTs. This idea was supported by the results of an investigation using a scanning tunneling microscope. It could be said that photoabsorption spectroscopy is useful for detecting ring formation in situ.

  13. Characterization of single-wall carbon nanotubes produced by CCVD method

    NASA Astrophysics Data System (ADS)

    Colomer, J.-F.; Benoit, J.-M.; Stephan, C.; Lefrant, S.; Van Tendeloo, G.; Nagy, J. B.

    2001-09-01

    Carbon single-wall nanotubes (SWNTs) can be produced by the catalytic chemical vapor deposition (CCVD) method. They are synthesized by catalytic decomposition of methane at 1000 °C on 2.5 wt% Co/MgO catalyst. SWNT samples have been characterized by transmission electron microscopy (TEM) and Raman spectroscopy. Using these two techniques, a comparison between the SWNTs produced by CCVD and synthesized by electric arc discharge has been made. Finally, we give conclusions about the diameter distribution and the electronic structure of SWNTs produced by the CCVD method.

  14. [Surface modification and microstructure of single-walled carbon nanotubes for dental composite resin].

    PubMed

    Xia, Yang; Zhang, Feimin; Xu, Li'na; Gu, Ning

    2006-12-01

    In order to improve its dispersion condition in dental composite resin and enhance its interaction with the matrix, single-walled carbon nanotubes(SWNTs) were refluxed and oxidized, then treated by APTE. Their outer surface were coated by nano-SiO2 particles using sol-gel process, then further treated by organosilanes ATES. IR and TEM were used to analyze modification results. TEM pictures showed nano-particles were on the surface of SWNTs; IR showed characteristic adsorbing bands of SiO2. Composite resin specimen with modified SWNTs was prepared and examined by TEM. SWNTs were detected in composite resin matrix among other inorganic fillers.

  15. Rayleigh-Ritz axial buckling analysis of single-walled carbon nanotubes with different boundary conditions

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Sahmani, S.; Rouhi, H.

    2011-02-01

    Eringen's nonlocality is incorporated into the shell theory to include the small-scale effects on the axial buckling of single-walled carbon nanotubes (SWCNTs) with arbitrary boundary conditions. To this end, the Rayleigh-Ritz solution technique is implemented in conjunction with the set of beam functions as modal displacement functions. Then, molecular dynamics simulations are employed to obtain the critical buckling loads of armchair and zigzag SWCNTs, the results of which are matched with those of nonlocal shell model to extract the appropriate values of nonlocal parameter. It is found that in contrast to the chirality, boundary conditions have a considerable influence on the proper values of nonlocal parameter.

  16. Electronic modulations in a single wall carbon nanotube induced by the Au(111) surface reconstruction

    SciTech Connect

    Clair, Sylvain; Shin, Hyung-Joon; Kim, Yousoo E-mail: maki@riken.jp; Kawai, Maki E-mail: maki@riken.jp

    2015-02-02

    The structural and electronic structure of single wall carbon nanotubes adsorbed on Au(111) has been investigated by low-temperature scanning tunneling microscopy and spectroscopy. The nanotubes were dry deposited in situ in ultrahigh vacuum onto a perfectly clean substrate. In some cases, the native herringbone reconstruction of the Au(111) surface interacted directly with adsorbed nanotubes and produced long-range periodic oscillations in their local density of states, corresponding to charge transfer modulations along the tube axis. This effect, however, was observed not systematically for all tubes and only for semiconducting tubes.

  17. Robust cyclohexanone selective chemiresistors based on single-walled carbon nanotubes.

    PubMed

    Frazier, Kelvin M; Swager, Timothy M

    2013-08-06

    Functionalized single-walled carbon nanotube (SWCNT)-based chemiresistors are reported for a highly robust and sensitive gas sensor to selectively detect cyclohexanone, a target analyte for explosive detection. The trifunctional selector has three important properties: it noncovalently functionalizes SWCNTs with cofacial π-π interactions, it binds to cyclohexanone via hydrogen bond (mechanistic studies were investigated), and it improves the overall robustness of SWCNT-based chemiresistors (e.g., humidity and heat). Our sensors produced reversible and reproducible responses in less than 30 s to 10 ppm of cyclohexanone and displayed an average theoretical limit of detection (LOD) of 5 ppm.

  18. En route toward high performance electronics based on single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cao, Qing

    2014-06-01

    Single-walled carbon nanotubes (SWNT) could replace silicon in high-performance electronics with their exceptional electrical properties and intrinsic ultra-thin body. During the past five years, the major focus of this field is gradually shifting from proof-of-concept prototyping in academia to technology development in industry with emphasis on manufacturability and integration issues. Here we will review some most significant recent advances, with focus on assembling high purity semiconducting SWNTs into well aligned arrays. Future challenges and research opportunities in this field will also be discussed.

  19. Aligned, ultralong single-walled carbon nanotubes: from synthesis, sorting, to electronic devices.

    PubMed

    Liu, Zhongfan; Jiao, Liying; Yao, Yagang; Xian, Xiaojun; Zhang, Jin

    2010-06-04

    Aligned, ultralong single-walled carbon nanotubes (SWNTs) represent attractive building blocks for nanoelectronics. The structural uniformity along their tube axis and well-ordered two-dimensional architectures on wafer surfaces may provide a straightforward platform for fabricating high-performance SWNT-based integrated circuits. On the way towards future nanoelectronic devices, many challenges for such a specific system also exist. This Review summarizes the recent advances in the synthesis, identification and sorting, transfer printing and manipulation, device fabrication and integration of aligned, ultralong SWNTs in detail together with discussion on their major challenges and opportunities for their practical application.

  20. Purification and alignment of arc-synthesis single-walled carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Huang, Houjin; Kajiura, Hisashi; Yamada, Atsuo; Ata, Masafumi

    2002-04-01

    We report here a scalable method for purification and alignment of single-walled carbon nanotubes (SWNT) in an aqueous solution. Arc-synthesis soot containing SWNTs is first treated with a concentrated nitric acid. After removal of most of the impurities and water, macroscopic and well-aligned SWNT bundles up to several centimeters long are formed in a rotary evaporator. Alignment of the SWNT bundles is ascribed to the liquid flow induced by rotary evaporation and van der Waals interactions among the bundles. The aligned SWNT bundles are further purified by ultrasonic Soxhlet extraction and annealing.

  1. Polymer functionalized n-type single wall carbon nanotube photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Li, Zhongrui; Saini, Viney; Dervishi, Enkeleda; Kunets, Vasyl P.; Zhang, Jianhui; Xu, Yang; Biris, Alexandru R.; Salamo, Gregory J.; Biris, Alexandru S.

    2010-01-01

    Photovoltaic conversion was achieved from high-density p-n heterojunctions formed between polymer functionalized n-type single wall carbon nanotubes (SWNTs) and underlying p-type Si substrate. Functionalization of SWNTs by amine-rich polymers results in the evolution of tubes from p-type to n-type, and the polyethylene imine (PEI) functionalized SWNT film can serve as both photogeneration sites and a charge carrier collecting/transport layer. Photoremoval of oxygen adsorbed on the nanotubes prior to PEI functionalization can increase the conversion efficiency of the polymer functionalized n-type SWNT photovoltaic devices.

  2. Sonochemical preparation of silica nanorods for gene delivery using single-walled carbon nanotubes as templates.

    PubMed

    Lee, Kyoung G; Min, Jung Sun; Wi, Rinbok; Kim, Jin Chul; Ahn, Jeong Keun; Kim, Do Hyun

    2011-01-01

    Silica nanorods were fabricated with single-walled carbon nanotubes (SWCNTs) via ultrasound. The diameter of the resulting SWCNT-silica particles ranged from 60 to 70 nm. The morphology of this composite material was investigated via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The individual SWCNTs are uniformly coated with silica and formed a unique nanocomposite material. The important role of ultrasound and the mechanism of silica layer formation on SWCNTs were explained via the hydrolysis of the silica source and the adsorption of the siloxane groups on the SWCNT surfaces under ultrasound irradiation. The amino-functionalized silica nanorods were demonstrated as non-viral vectors for gene delivery.

  3. Purification of single-wall carbon nanotubes by using ultrafine gold particles

    NASA Astrophysics Data System (ADS)

    Nihey, Fumiyuki; Mizoguti, Eiji; Yudasaka, Masako; Iijima, Sumio; Ichihashi, Toshinari; Nakamura, Kazuo

    2000-03-01

    The purification of single-wall carbon nanotubes (SWNTs) is needed to enable detailed characterization and some application of this material. We report a purification method utilizing ultrafine gold particles as catalysts to selectively oxidize carbonaceous impurities in SWNT soot. The ultrafine gold particles with a diameter of 20 nm were dispersed in the soot in combination with benzalkonium chloride as surfactant. Thermogravimetric analyses and electron microscopy observations revealed that oxidation occured at about 330^circC for carbonaceous impurities and at about 410^circC for SWNTs. This selective oxidation enabled us to purify SWNTs and make the quantitative analyses of SWNTs.

  4. Transmission electron microscopy and electrical transport investigations performed on the same single-walled carbon nanotube

    SciTech Connect

    Philipp, G.; Burghard, M.; Roth, S.

    1998-08-11

    Electrical transport measurements and high resolution transmission electron microscopy performed on the same (rope of) single-walled carbon nanotube(s) (SWCNTs) allow to establish links between structural and electronic properties of the tubes. The tubes are deposited on electron transparent ultrathin Si{sub 3}N{sub 4}-membranes bearing Cr/AuPd-electrodes defined by electron beam lithography. TEM-micrographs of the setup reveal mostly ropes consisting of 2-3 tubes which also appear on a scanning force microscope image of the same area. A current-voltage trace of the ropes at 4.2 K is also presented.

  5. Saturable absorption of film composites with single-walled carbon nanotubes and graphene.

    PubMed

    Khudyakov, Dmitry V; Borodkin, Andrey A; Lobach, Anatoly S; Ryzhkov, Aleksandr V; Vartapetov, Sergey K

    2013-01-10

    Saturable absorption of polymer film composites with single-walled carbon nanotubes (SWNTs) and multilayer graphene (GR) were studied by Z- and P-scan methods with femtosecond probing pulses at a wavelength of 1.06 μm. As a matrix for the composite film, a polymer carboxymethylcellulose (CMC) was used. For these composites, the dependence of transmittance on peak intensity of a probe pulse was shown. The values of saturation intensities for the GR-CMC and SWNT-CMC composites were determined by the different methods. The intensities at which optical damage of the composites occurs were estimated.

  6. The effect of the environment on the electronic properties of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shandakov, S. D.; Lomakin, M. V.; Nasibulin, A. G.

    2016-11-01

    We present optical absorption spectra of single-walled carbon nanotube (SWNT) films obtained after 1-year-long film storage in air and upon heating up to 250°C. The results of the investigation show that long-term storage of the SWNTs in normal atmosphere leads to a substantial drop in intensity of optical absorption caused by electronic excitation, which recovers after film heating. The mechanism of changes in the electronic properties of the SWNTs under the influence of environment is discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

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

  8. Molecular adsorption study of nicotine and caffeine on single-walled carbon nanotubes from first principles

    NASA Astrophysics Data System (ADS)

    Lee, Hyung-June; Kim, Gunn; Kwon, Young-Kyun

    2013-08-01

    Using first-principles calculations, we investigate the electronic structures and binding properties of nicotine and caffeine adsorbed on single-walled carbon nanotubes to determine whether CNTs are appropriate for filtering or sensing nicotine and caffeine molecules. We find that caffeine adsorbs more strongly than nicotine. The different binding characteristics are discussed by analyzing the modification of the electronic structure of the molecule-adsorbed CNTs. We also calculate the quantum conductance of the CNTs in the presence of nicotine or caffeine adsorbates and demonstrate that the influence of caffeine is stronger than nicotine on the conductance of the host CNT.

  9. Effect of Topological Defects on Buckling Behavior of Single-walled Carbon Nanotube.

    PubMed

    Ranjbartoreh, Ali Reza; Wang, Guoxiu

    2011-12-01

    Molecular dynamic simulation method has been employed to consider the critical buckling force, pressure, and strain of pristine and defected single-walled carbon nanotube (SWCNT) under axial compression. Effects of length, radius, chirality, Stone-Wales (SW) defect, and single vacancy (SV) defect on buckling behavior of SWCNTs have been studied. Obtained results indicate that axial stability of SWCNT reduces significantly due to topological defects. Critical buckling strain is more susceptible to defects than critical buckling force. Both SW and SV defects decrease the buckling mode of SWCNT. Comparative approach of this study leads to more reliable design of nanostructures.

  10. Record Endurance for Single-Walled Carbon Nanotube–Based Memory Cell

    PubMed Central

    2010-01-01

    We study memory devices consisting of single-walled carbon nanotube transistors with charge storage at the SiO2/nanotube interface. We show that this type of memory device is robust, withstanding over 105 operating cycles, with a current drive capability up to 10−6 A at 20 mV drain bias, thus competing with state-of-the-art Si-devices. We find that the device performance depends on temperature and pressure, while both endurance and data retention are improved in vacuum. PMID:21124628

  11. The modification of benzene adsorption on zigzag single-wall carbon nanotubes by carboxylation

    NASA Astrophysics Data System (ADS)

    Hamadanian, Masood; Tavangar, Zahra; Naseh, Sara

    2016-12-01

    In this work, the adsorption of benzene molecule on (10,0) functionalized zigzag single-wall carbon nanotubes was studied using density functional theory. Geometric structures, adsorption energies and electronic properties of five supercells were investigated. It was found that the carboxylation causes a notable increment in the adsorption capability of SWCNT in uptaking benzene as a pollutant molecule. The highest absorbency was achieved when benzene molecule had interaction with both SWCNT and COOH functional group through π-π interaction and hydrogen bonding.

  12. Pore structure of raw and purified HiPco single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cinke, Martin; Li, Jing; Chen, Bin; Cassell, Alan; Delzeit, Lance; Han, Jie; Meyyappan, M.

    2002-10-01

    Very high purity single-walled carbon nanotubes (SWNTs) were obtained from HiPco SWNT samples containing Fe particles by a two-step purification process. The raw and purified samples were characterized using high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and thermogravimetric analysis (TGA). The purified sample consists of ˜0.4% Fe and the process does not seem to introduce any additional defects. The N 2 adsorption isotherm studies at 77 K reveal that the total surface area of the purified sample increases to 1587 m 2/g from 567 m 2/g for the raw material, which is the highest value reported for SWNTs.

  13. Temperature Dependence of the Thermal Conductivity of Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Osman, Mohamed A.; Srivastava, Deepak

    2000-01-01

    The thermal conductivity of several single wall carbon nanotubes (CNT) has been calculated over a temperature range of 100-500 K using molecular dynamics simulations with Tersoff-Brenner potential for C-C interactions. In all cases, starting from similar values at 100K, thermal conductivities show a peaking behavior before falling off at higher temperatures. The peak position shifts to higher temperatures for nanotubes of larger diameter, and no significant dependence on the tube chirality is observed. It is shown that this phenomenon is due to onset of Umklapp scattering, which shifts to higher temperatures for nanotubes of larger diameter.

  14. One-dimensional silver nanostructures on single-wall carbon nanotubes.

    PubMed

    Mercado, Eunice; Santiago, Steven; Baez, Luis; Rivera, Daniel; Gonzalez, Miguel; Rivera-Ramos, Milton E; Leon, Madeline; Castro, Miguel E

    2011-11-23

    We report the synthesis and characterization of one-dimensional silver nanostructures using single-wall carbon nanotubes (SWCNT) as a template material. Transmission electron microscopy and scanning tunneling microscopy are consistent with the formation of a one-dimensional array of silver particles on SWCNT. We observe evidence for the excitation of the longitudinal silver plasmon mode in the optical absorption spectra of Ag-SWCNT dispersions, even in the lowest silver concentrations employed. The results indicate that silver deposits on SWCNT may be candidates for light-to-energy conversion through the coupling of the electric field excited in arrays of plasmonic particles.

  15. Transparent and flexible high-performance supercapacitors based on single-walled carbon nanotube films

    NASA Astrophysics Data System (ADS)

    Kanninen, Petri; Dang Luong, Nguyen; Hoang Sinh, Le; Anoshkin, Ilya V.; Tsapenko, Alexey; Seppälä, Jukka; Nasibulin, Albert G.; Kallio, Tanja

    2016-06-01

    Transparent and flexible energy storage devices have garnered great interest due to their suitability for display, sensor and photovoltaic applications. In this paper, we report the application of aerosol synthesized and dry deposited single-walled carbon nanotube (SWCNT) thin films as electrodes for an electrochemical double-layer capacitor (EDLC). SWCNT films exhibit extremely large specific capacitance (178 F g-1 or 552 μF cm-2), high optical transparency (92%) and stability for 10 000 charge/discharge cycles. A transparent and flexible EDLC prototype is constructed with a polyethylene casing and a gel electrolyte.

  16. The separation single-wall carbon nanotubes on length by sepharose gel

    NASA Astrophysics Data System (ADS)

    Ren, LingLing; Zhao, MingYuan; Wang, ZhiHua

    2012-07-01

    The separations of single-wall carbon nanotubes on length by sepharose gel were investigated in this work. The solutions of sodium dodecyl sulfate and sodium deoxycholate were applied as the eluent in sequence. SEM and Raman were used to characterize the length of nanotube bundles. The results show that the longer nanotubes were eluted out first, and then the shorter tubes were followed by the sodium dodecyl sulfate. However, the separated order was totally reversed by the sodium deoxycholate. By this method, the process generated nanotube fractions not only were narrower in length distributions, but also could control the separation orders by changing the eluents. Moreover, the separation principle was also discussed.

  17. Fine Structure of the Low-Frequency Raman Phonon Bands of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Iliev, M. N.; Litvinchuk, A. P.; Arepalli, S.; Nikolaev, P.; Scott, C. D.

    1999-01-01

    The Raman spectra of singled-wall carbon nanotubes (SWNT) produced by laser and are process were studied between 5 and 500 kappa. The line width vs. temperature dependence of the low-frequency Raman bands between 150 and 200/ cm deviates from that expected for phonon decay through phonon-phonon scattering mechanism. The experimental results and their analysis provided convincing evidence that each of the low-frequency Raman lines is a superposition of several narrower Raman lines corresponding to tubes of nearly the same diameter. The application of Raman spectroscopy to probe the distribution of SWNT by both diameter and chirality is discussed.

  18. On the charge transfer between single-walled carbon nanotubes and graphene

    SciTech Connect

    Rao, Rahul Pierce, Neal; Dasgupta, Archi

    2014-08-18

    It is important to understand the electronic interaction between single-walled carbon nanotubes (SWNTs) and graphene in order to use them efficiently in multifunctional hybrid devices. Here, we deposited SWNT bundles on graphene-covered copper and SiO{sub 2} substrates by chemical vapor deposition and investigated the charge transfer between them by Raman spectroscopy. Our results revealed that, on both copper and SiO{sub 2} substrates, graphene donates electrons to the SWNTs, resulting in p-type doped graphene and n-type doped SWNTs.

  19. Separation of CO2-CH4 mixtures on defective single walled carbon nanohorns--tip does matter.

    PubMed

    Furmaniak, Sylwester; Terzyk, Artur P; Kowalczyk, Piotr; Kaneko, Katsumi; Gauden, Piotr A

    2013-10-21

    Using realistic models of single-walled carbon nanohorns and their single-walled carbon nanotube counterparts, we study the equilibrium separation of CO2-CH4 mixtures near ambient operating conditions by using molecular simulations. We show that regardless of the studied operating conditions (i.e., total CO2-CH4 mixture pressures and mole fractions of mixture components in the bulk phase), single-walled carbon nanohorns maximize the CO2-CH4 equilibrium separation factor. Optimized samples of single-walled carbon nanohorns consisting of narrow tubular parts capped with horn-shaped tips show highly selective adsorption of CO2 over the CH4 mixture component, with the CO2-CH4 equilibrium separation factor of ~8-12. A large surface-to-volume ratio (i.e., enhanced surface forces) and unique defective morphology (i.e., packing of adsorbed molecules in quasi-one/quasi-zero dimensional nanospaces) of single-walled carbon nanohorns are their key structural properties responsible for the excellent separation performance. Our theoretical simulation results are in quantitative agreement with a recent experimental/theoretical study of the CO2-CH4 adsorption and separation on oxidized single-walled carbon nanohorns [Ohba et al., Chem. Lett., 40, 2011, 1089]. Both experiment and theory showed that the CO2-CH4 equilibrium separation factor of oxidized samples of single-walled nanohorns measured near ambient operating conditions is ~2-5. This reduction in the separation efficiency as compared to optimized samples of single-walled carbon nanohorns is theoretically justified by their lower surface-to-volume ratio (i.e., larger diameters of tubular parts and horn-shaped tips).

  20. Efficient Charge Extraction and Slow Recombination in Organic-Inorganic Perovskites Capped with Semiconducting Single-Walled Carbon Nanotubes

    SciTech Connect

    Ihly, Rachelle; Dowgiallo, Anne-Marie; Yang, Mengjin; Schulz, Philip; Stanton, Noah J.; Reid, Obadiah G.; Ferguson, Andrew J.; Zhu, Kai; Berry, Joseph J.; Blackburn, Jeffrey L.

    2016-04-01

    Metal-halide based perovskite solar cells have rapidly emerged as a promising alternative to traditional inorganic and thin-film photovoltaics. Although charge transport layers are used on either side of perovskite absorber layers to extract photogenerated electrons and holes, the time scales for charge extraction and recombination are poorly understood. Ideal charge transport layers should facilitate large discrepancies between charge extraction and recombination rates. Here, we demonstrate that highly enriched semiconducting single-walled carbon nanotube (SWCNT) films enable rapid (sub-picosecond) hole extraction from a prototypical perovskite absorber layer and extremely slow back-transfer and recombination (hundreds of microseconds). The energetically narrow and distinct spectroscopic signatures for charges within these SWCNT thin films enables the unambiguous temporal tracking of each charge carrier with time-resolved spectroscopies covering many decades of time. The efficient hole extraction by the SWCNT layer also improves electron extraction by the compact titanium dioxide electron transport layer, which should reduce charge accumulation at each critical interface. Finally, we demonstrate that the use of thin interface layers of semiconducting single-walled carbon nanotubes between the perovskite absorber layer and a prototypical hole transport layer improves device efficiency and stability, and reduces hysteresis.

  1. Organized assemblies of single wall carbon nanotubes and porphyrin for photochemical solar cells: charge injection from excited porphyrin into single-walled carbon nanotubes.

    PubMed

    Hasobe, Taku; Fukuzumi, Shunichi; Kamat, Prashant V

    2006-12-21

    Photochemical solar cells have been constructed from organized assemblies of single-walled carbon nanotubes (SWCNT) and protonated porphyrin on nanostructured SnO2 electrodes. The protonated form of porphyrin (H4P2+) and SWCNT composites form 0.5-3.0 microm-sized rodlike structures and they can be assembled onto nanostructured SnO2 films [optically transparent electrode OTE/SnO2] by an electrophoretic deposition method. These organized assemblies are photoactive and absorb strongly in the entire visible region. The incident photon to photocurrent efficiency (IPCE) of OTE/SnO2/SWCNT-H4P2+ is approximately 13% at an applied potential of 0.2 V versus saturated calomel electrode. Femtosecond pump-probe spectroscopy experiments confirm the decay of the excited porphyrin in the SWCNT-H4P2+ assembly as it injects electrons into SWCNT. The dual role of SWCNT in promoting photoinduced charge separation and facilitating charge transport is presented.

  2. Encapsulation of carbon chain molecules in single-walled carbon nanotubes.

    PubMed

    Kuwahara, Riichi; Kudo, Yohei; Morisato, Tsuguo; Ohno, Kaoru

    2011-05-26

    The vacuum space inside carbon nanotubes offers interesting possibilities for the inclusion, transportation, and functionalization of foreign molecules. Using first-principles density functional calculations, we show that linear carbon-based chain molecules, namely, polyynes (C(m)H(2), m = 4, 6, 10) and the dehydrogenated forms C(10)H and C(10), as well as hexane (C(6)H(14)), can be spontaneously encapsulated in open-ended single-walled carbon nanotubes (SWNTs) with edges that have dangling bonds or that are terminated with hydrogen atoms, as if they were drawn into a vacuum cleaner. The energy gains when C(10)H(2), C(10)H, C(10), C(6)H(2), C(4)H(2), and C(6)H(14) are encapsulated inside a (10,0) zigzag-shaped SWNT are 1.48, 2.04, 2.18, 1.05, 0.55, and 1.48 eV, respectively. When these molecules come inside a much wider (10,10) armchair SWNT along the tube axis, they experience neither an energy gain nor an energy barrier. They experience an energy gain when they approach the tube walls inside. Three hexane molecules can be encapsulated parallel to each other (i.e., nested) inside a (10,10) SWNT, and their energy gain is 1.98 eV. Three hexane molecules can exhibit a rotary motion. One reason for the stability of carbon chain molecules inside SWNTs is the large area of weak wave function overlap. Another reason concerns molecular dependence, that is, the quadrupole-quadrupole interaction in the case of the polyynes and electron charge transfer from the SWNT in the case of the dehydrogenated forms. The very flat potential surface inside an SWNT suggests that friction is quite low, and the space inside SWNTs serves as an ideal environment for the molecular transport of carbon chain molecules. The present theoretical results are certainly consistent with recent experimental results. Moreover, the encapsulation of C(10) makes an SWNT a (purely carbon-made) p-type acceptor. Another interesting possibility associated with the present system is the direction

  3. Tethered anthracene pair as molecular tweezers for post-production separation of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Anderson, Ankoma; Yang, Fengchun; Cao, Li; Li, Huaping; Meziani, Mohammed J.; Sun, Ya-Ping

    2016-07-01

    As-produced single-walled carbon nanotubes (SWNTs) are metallic and semiconducting mixtures. An anthracene mono-derivative with a long alkyl tail and a molecule with a tethered pair of anthracene species (bis-anthracene) in a ;molecular tweezers;-like configuration were synthesized and evaluated for the separation of SWNTs. While the mono-derivative was incapable of the noncovalent functionalization-solubilization, the bis-anthracene was found to be very effective. The results suggest that molecular tweezers of a tethered pair of planar aromatic species can be coupled with the selection of a suitable solvent or solvent mixture for effective and efficient post-production separation of metallic and semiconducting SWNTs.

  4. Spectroelectrochemical properties of the single walled carbon nanotubes functionalized with polydiphenylamine doped with heteropolyanions

    SciTech Connect

    Smaranda, I.; Baibarac, M.; Baltog, I.; Mevellec, J.Y.; Lefrant, S.

    2013-01-15

    A combined chemical-electrochemical method was used for covalent functionalization of single-walled carbon nanotube (SWNT) with polydiphenylamine (PDPA) doped with heteropolyanions of H{sub 3}PMo{sub 12}O{sub 40}{center_dot}xH{sub 2}O. The functionalization process induces in Raman spectra of SWNTs the following changes: (i) an increase in relative intensity of the D band, accompanied a gradual up-shift of the G band in the case of the semiconducting tubes and a decrease in the relative intensity of band peaked at 1540 cm{sup -1} is remarked in the case of the metallic tubes; (ii) in the anti-Stokes Raman spectrum an increase in the relative intensity of Raman line of metallic tubes peaked at -1560 cm{sup -1} is remarked when the cycles number increases. The additional down-shift of the FTIR bands belonging to H{sub 3}PMo{sub 12}O{sub 40} heteropolyanions (at 881, 943 and 1055 cm{sup -1}) and PDPA (at 688, 736 and 1016 cm{sup -1}) originates in hindrance steric effects induced the covalent functionalization of SWNTs with polymer molecules. Using Raman scattering and FTIR spectroscopy we demonstrate that chemical polymerization of diphenylamine in the presence of H{sub 3}PMo{sub 12}O{sub 40}{center_dot}xH{sub 2}O and SWNTs results in a composite of the type blend based on PDPA in un-doped state and SWNTs doped with H{sub 3}PMo{sub 12}O{sub 40} heteropolyanions. - Graphical abstract: Stokes and anti-Stokes Raman spectra of the SWNTs before (a) and after electrochemical functionalization with PDPA doped with heteropolyanions by 5 (b) and 25 (c) voltammeter cycles. Highlights: Black-Right-Pointing-Pointer A chemical-electrochemical method is used to functionalization of SWNTs. Black-Right-Pointing-Pointer Functionalization of wall-side of tube is evidenced by anti-Stokes Raman studies. Black-Right-Pointing-Pointer FTIR spectra proves insertion of heteropolyanions in polydiphenylamine matrix. Black-Right-Pointing-Pointer FTIR spectra of polymer functionalized SWNTs

  5. Molecular electronic devices based on single-walled carbon nanotube electrodes.

    PubMed

    Feldman, Alina K; Steigerwald, Michael L; Guo, Xuefeng; Nuckolls, Colin

    2008-12-01

    As the top-down fabrication techniques for silicon-based electronic materials have reached the scale of molecular lengths, researchers have been investigating nanostructured materials to build electronics from individual molecules. Researchers have directed extensive experimental and theoretical efforts toward building functional optoelectronic devices using individual organic molecules and fabricating metal-molecule junctions. Although this method has many advantages, its limitations lead to large disagreement between experimental and theoretical results. This Account describes a new method to create molecular electronic devices, covalently bridging a gap in a single-walled carbon nanotube (SWNT) with an electrically functional molecule. First, we introduce a molecular-scale gap into a nanotube by precise oxidative cutting through a lithographic mask. Now functionalized with carboxylic acids, the ends of the cleaved carbon nanotubes are reconnected with conjugated diamines to give robust diamides. The molecular electronic devices prepared in this fashion can withstand and respond to large environmental changes based on the functional groups in the molecules. For example, with oligoanilines as the molecular bridge, the conductance of the device is sensitive to pH. Similarly, using diarylethylenes as the bridge provides devices that can reversibly switch between conjugated and nonconjugated states. The molecular bridge can perform the dual task of carrying electrical current and sensing/recognition through biological events such as protein/substrate binding and DNA hybridization. The devices based on DNA can measure the difference in electrical properties of complementary and mismatched strands. A well-matched duplex DNA 15-mer in the gap exhibits a 300-fold lower resistance than a duplex with a GT or CA mismatch. This system provides an ultrasensitive way to detect single-nucleotide polymorphisms at the individual molecule level. Restriction enzymes can cleave

  6. Theoretical Studies of the Interaction of Excitons with Charged Impurities in Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Tayo, Benjamin O.

    A fundamental theory of the electronic and optical properties of semiconductors shows the importance of impurities, which are often unavoidable and can alter intrinsic properties of semiconductor materials substantially. While the subject of impurity doping is well understood in bulk semiconductors, the role and impact of doping in low dimensional materials like carbon nanotubes is still under investigation and there exists significant debate on the exact nature of electronic impurity levels in single-walled carbon nanotubes associated with adatoms. In this work, we address the role of impurities in single-walled carbon nanotubes. A simple model is developed for studying the interaction of bright (singlet) excitons in semiconducting single-wall nanotubes with charged impurities. The model reveals a red shift in the energy of excitonic states in the presence of an impurity, thus indicating binding of excitons in the impurity potential well. Signatures of several bound states were found in the absorption spectrum below the onset of excitonic optical transitions in the bare nanotube. The dependence of the binding energy on the model parameters, such as impurity charge and position, was determined and analytical fits were derived for a number of tubes of different diameter. The nanotube family splitting is seen in the diameter dependence, gradually decreasing with the diameter. By calculating the partial absorption coefficient for a small segment of nanotube the local nature of the wave function of the bound states was derived. Our studies provide useful insights into the role of the physical environment (here, a charged impurity atom) in the manipulation of the excited states of carbon nanotubes. We performed very detailed calculations of the electronic and optical properties of carbon nanotubes in the presence of an immobile impurity atom, thus going beyond previous many-body perturbation theory (MBPT) studies in which the carbon nanotubes were considered in vacuum

  7. Self-repairing in single-walled carbon nanotubes by heat treatment

    NASA Astrophysics Data System (ADS)

    Jiang, Jin-Wu; Wang, Jian-Sheng

    2010-09-01

    Structure transformation by heat treatment in single-walled carbon nanotubes (SWCNT) is investigated using molecular dynamics simulation. The critical temperature for the collapse of pure SWCNT is as high as 4655 K due to strong covalent carbon-carbon bonding. Above 2000 K, the cross section of SWCNT changes from circle to ellipse. The self-repairing capability is then investigated and two efficient processes are observed for the SWCNT to repair themselves. (1) In the first mechanism, vacancy defects aggregate to form a bigger hole, and a bottleneck junction is constructed nearby. (2) In the second mechanism, a local curvature is generated around the isolate vacancy to smooth the SWCNT. Benefit from the powerful self-repairing capability, defective SWCNT can seek a stable configuration at high temperatures; thus the critical temperature for collapse is insensitive to the vacancy defect density.

  8. Near-field imaging of single walled carbon nanotubes emitting in the telecom wavelength range

    NASA Astrophysics Data System (ADS)

    La China, F.; Caselli, N.; Sarti, F.; Biccari, F.; Torrini, U.; Intonti, F.; Vinattieri, A.; Durán-Valdeiglesias, E.; Alonso Ramos, C.; Le Roux, X.; Balestrieri, M.; Filoramo, A.; Vivien, L.; Gurioli, M.

    2016-09-01

    Hybrid systems based on carbon nanotubes emitting in the telecom wavelength range and Si-photonic platforms are promising candidates for developing integrated photonic circuits. Here, we consider semiconducting single walled carbon nanotubes (s-SWNTs) emitting around 1300 nm or 1550 nm wavelength. The nanotubes are deposited on quartz substrate for mapping their photoluminescence in hyperspectral near-field microscopy. This method allows for a sub-wavelength resolution in detecting the spatial distribution of the emission of single s-SWNTs at room temperature. Optical signature delocalized over several micrometers is observed, thus denoting the high quality of the produced carbon nanotubes on a wide range of tube diameters. Noteworthy, the presence of both nanotube bundles and distinct s-SWNT chiralities is uncovered.

  9. Quantum dot-like excitonic behavior in individual single walled-carbon nanotubes

    PubMed Central

    Wang, Xu; Alexander-Webber, Jack A.; Jia, Wei; Reid, Benjamin P. L.; Stranks, Samuel D.; Holmes, Mark J.; Chan, Christopher C. S.; Deng, Chaoyong; Nicholas, Robin J.; Taylor, Robert A.

    2016-01-01

    Semiconducting single-walled carbon nanotubes are one-dimensional materials with great prospects for applications such as optoelectronic and quantum information devices. Yet, their optical performance is hindered by low fluorescent yield. Highly mobile excitons interacting with quenching sites are attributed to be one of the main non-radiative decay mechanisms that shortens the exciton lifetime. In this paper we report on time-integrated photoluminescence measurements on individual polymer wrapped semiconducting carbon nanotubes. An ultra narrow linewidth we observed demonstrates intrinsic exciton dynamics. Furthermore, we identify a state filling effect in individual carbon nanotubes at cryogenic temperatures as previously observed in quantum dots. We propose that each of the CNTs is segmented into a chain of zero-dimensional states confined by a varying local potential along the CNT, determined by local environmental factors such as the amount of polymer wrapping. Spectral diffusion is also observed, which is consistent with the tunneling of excitons between these confined states. PMID:27849046

  10. XPS Protocol for the Characterization of Pristine and Functionalized Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Sosa, E. D.; Allada, R.; Huffman, C. B.; Arepalli, S.

    2009-01-01

    Recent interest in developing new applications for carbon nanotubes (CNT) has fueled the need to use accurate macroscopic and nanoscopic techniques to characterize and understand their chemistry. X-ray photoelectron spectroscopy (XPS) has proved to be a useful analytical tool for nanoscale surface characterization of materials including carbon nanotubes. Recent nanotechnology research at NASA Johnson Space Center (NASA-JSC) helped to establish a characterization protocol for quality assessment for single wall carbon nanotubes (SWCNTs). Here, a review of some of the major factors of the XPS technique that can influence the quality of analytical data, suggestions for methods to maximize the quality of data obtained by XPS, and the development of a protocol for XPS characterization as a complementary technique for analyzing the purity and surface characteristics of SWCNTs is presented. The XPS protocol is then applied to a number of experiments including impurity analysis and the study of chemical modifications for SWCNTs.

  11. Nerve agent detection using networks of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Novak, J. P.; Snow, E. S.; Houser, E. J.; Park, D.; Stepnowski, J. L.; McGill, R. A.

    2003-11-01

    We report the use of carbon nanotubes as a sensor for chemical nerve agents. Thin-film transistors constructed from random networks of single-walled carbon nanotubes were used to detect dimethyl methylphosphonate (DMMP), a simulant for the nerve agent sarin. These sensors are reversible and capable of detecting DMMP at sub-ppb concentration levels, and they are intrinsically selective against interferent signals from hydrocarbon vapors and humidity. We provide additional chemical specificity by the use of filters coated with chemoselective polymer films. These results indicate that the electronic detection of sub-ppb concentrations of nerve agents and potentially other chemical warfare agents is possible with simple-to-fabricate carbon nanotube devices.

  12. Quantum dot-like excitonic behavior in individual single walled-carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Alexander-Webber, Jack A.; Jia, Wei; Reid, Benjamin P. L.; Stranks, Samuel D.; Holmes, Mark J.; Chan, Christopher C. S.; Deng, Chaoyong; Nicholas, Robin J.; Taylor, Robert A.

    2016-11-01

    Semiconducting single-walled carbon nanotubes are one-dimensional materials with great prospects for applications such as optoelectronic and quantum information devices. Yet, their optical performance is hindered by low fluorescent yield. Highly mobile excitons interacting with quenching sites are attributed to be one of the main non-radiative decay mechanisms that shortens the exciton lifetime. In this paper we report on time-integrated photoluminescence measurements on individual polymer wrapped semiconducting carbon nanotubes. An ultra narrow linewidth we observed demonstrates intrinsic exciton dynamics. Furthermore, we identify a state filling effect in individual carbon nanotubes at cryogenic temperatures as previously observed in quantum dots. We propose that each of the CNTs is segmented into a chain of zero-dimensional states confined by a varying local potential along the CNT, determined by local environmental factors such as the amount of polymer wrapping. Spectral diffusion is also observed, which is consistent with the tunneling of excitons between these confined states.

  13. Unveiling the Evolutions of Nanotube Diameter Distribution during the Growth of Single-Walled Carbon Nanotubes.

    PubMed

    Navas, Hugo; Picher, Matthieu; Andrieux-Ledier, Amandine; Fossard, Frédéric; Michel, Thierry; Kozawa, Akinari; Maruyama, Takahiro; Anglaret, Eric; Loiseau, Annick; Jourdain, Vincent

    2017-03-28

    In situ and ex situ Raman measurements were used to study the dynamics of the populations of single-walled carbon nanotubes (SWCNTs) during their catalytic growth by chemical vapor deposition. Our study reveals that the nanotube diameter distribution strongly evolves during SWCNT growth but in dissimilar ways depending on the growth conditions. We notably show that high selectivity can be obtained using short or moderate growth times. High-resolution transmission electron microscopy observations support that Ostwald ripening is the key process driving these seemingly contradictory results by regulating the size distribution and lifetime of the active catalyst particles. Ostwald ripening appears as the main termination mechanism for the smallest diameter tubes, whereas carbon poisoning dominates for the largest ones. By unveiling the key concept of dynamic competition between nanotube growth and catalyst ripening, we show that time can be used as an active parameter to control the growth selectivity of carbon nanotubes and other 1D systems.

  14. Electron paramagnetic resonance investigation of purified catalyst-free single-walled carbon nanotubes.

    PubMed

    Zaka, Mujtaba; Ito, Yasuhiro; Wang, Huiliang; Yan, Wenjing; Robertson, Alex; Wu, Yimin A; Rümmeli, Mark H; Staunton, David; Hashimoto, Takeshi; Morton, John J L; Ardavan, Arzhang; Briggs, G Andrew D; Warner, Jamie H

    2010-12-28

    Electron paramagnetic resonance of single-walled carbon nanotubes (SWCNTs) has been bedevilled by the presence of paramagnetic impurities. To address this, SWCNTs produced by laser ablation with a nonmagnetic PtRhRe catalyst were purified through a multiple step centrifugation process in order to remove amorphous carbon and catalyst impurities. Centrifugation of a SWCNT solution resulted in sedimentation of carbon nanotube bundles containing clusters of catalyst particles, while isolated nanotubes with reduced catalyst particle content remained in the supernatant. Further ultracentrifugation resulted in highly purified SWCNT samples with a narrow diameter distribution and almost no detectable catalyst particles. Electron paramagnetic resonance (EPR) signals were detected only for samples which contained catalyst particles, with the ultracentrifuged SWCNTs showing no EPR signal at X-band (9.4 GHz) and fields < 0.4 T.

  15. Single-Walled Carbon Nanotubes Functionalized with Carboxylic Acid for Fabricating Polymeric Composite Microstructures.

    PubMed

    Otuka, Adriano José Galvani; Tribuzi, Vinicius; Cardoso, Marcos Roberto; de Almeida, Gustavo Foresto Brito; Zanatta, Antonio Ricardo; Corrêa, Daniel Souza; Mendonça, Cleber Renato

    2015-12-01

    Carbon nanotube composites are promising materials for mechanical and electrical applications. However, methodologies to incorporate carbon nanotubes in polymeric matrices are on high demand, especially for fabricating devices in the micro-nanoscale. In this paper we show the fabrication of 3D polymeric microstructures with functionalized single-walled carbon nanotubes (SWCNT), by means of two-photon polymerization (2PP). We used a range of SWCNT concentrations (0.01-1 wt%) in the resin to fabricate the composite material. Scanning electron microscopy images show the fabricated microstructures surface quality. Raman spectroscopy was used to confirm the presence and evaluate the distribution of SWCNT in the microstructures. Atomic force microscopy was used to evaluate the mechanical properties of the fabricated microstructures.

  16. Electric field dependence of photoluminescence from individual single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yasukochi, S.; Murai, T.; Shimada, T.; Chiashi, S.; Maruyama, S.; Kato, Y. K.

    2011-03-01

    Using suspended single-walled carbon nanotubes, we investigate electric field effects on photoluminescence. Trenches are fabricated on Si O2 /Si substrates, and Pt is deposited for electrical contacts. Carbon nanotubes are grown by patterned chemical vapor deposition. These devices operate as back-gate field effect transistors, allowing application of electric fields on as-grown ultraclean nanotubes. Individual suspended carbon nanotubes are identified by taking photoluminescence images using a home-built laser-scanning confocal microscope. After determining the chirality by photoluminescence excitation spectra, we measure gate voltage dependence of photoluminescence. We observe quenching of photoluminescence intensity and shifts of emission wavelength as gate voltages are applied. This work is supported by KAKENHI, Mizuho Foundation for the Promotion of Sciences, Research Foundation for Opto-Science and Technology, TEPCO Research Foundation, SCAT, SCOPE, and Photon Frontier Network Program of MEXT, Japan.

  17. Flavin-derived self-organization and chirality separation of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ju, Sang-Yong

    2008-07-01

    Formed by rolling up a two-dimensional sheet of one or more layer of graphite, graphene, carbon nanotubes (SWNTs) are the marvel materials of modern materials science. They are phenomenally strong and stiff, and have the unusual property of being excellent conductors of heat along the tube's axis, but good thermal insulators across it. But it is their electrical characteristics that excite the most interest. Especially, single-walled carbon nanotube (SWNTs), formed by one layer of cylindrical graphene, has better physical properties over multi-walled carbon nanotubes (MWNTs) having over two layer of graphene. Depending on the precise way they are rolled up, which is defined by ( n,m) vector, SWNTs can be made into either metals or semiconductors. So far, SWNTs can generally only be fabricated in batches that vary widely, both in the diameter of the individual tubes and in the orientation of their graphene lattice relative to the tube axis, the property known as chirality. Separating out these various conformations is a challenging, but one that must be solved if nanotubes are ever to fulfill their electrifying potential in devices. This thesis presents that flavin-based helical self-assembly can impart multi degrees of SWNTs separation (i.e., metallicity, diameter, chirality, and handedness). As opening chapters for carbon nanotube and flavin derivative, Chapter 1 provide the introduction of carbon nanotubes, especially single-walled tubes, and the current state-of-the-art nanotube separation. Also, Chapter 1 presents a variety of naturally-occurring flavin derivatives, their redox behavior, and their biological utilization as cofactors for various proteins. Motivated by chemoluminescence of flavin mononucleotide (FMN, phosphorylated form of Vitamin B2) with bacterial luciferase, Chapter 2 discuss about the synthesis and covalent attachment of flavin mononucleotide (FMN, phosphorylated form of Vitamin B2) analogue to oxidized SWNTs. Along with nine step synthesis

  18. Global Phospholipidomics Analysis Reveals Selective Pulmonary Peroxidation Profiles Upon Inhalation of Single Walled Carbon Nanotubes

    PubMed Central

    Tyurina, Yulia Y.; Kisin, Elena R.; Murray, Ashley; Tyurin, Vladimir A.; Kapralova, Valentina I.; Sparvero, Louis J.; Amoscato, Andrew A.; Samhan-Arias, Alejandro K.; Swedin, Linda; Lahesmaa, Riitta; Fadeel, Bengt; Shvedova, Anna A.; Kagan, Valerian E.

    2011-01-01

    It is commonly believed that nanomaterials cause non-specific oxidative damage. Our mass spectrometry-based oxidative lipidomics analysis of all major phospholipid classes revealed highly selective patterns of pulmonary peroxidation after inhalation exposure of mice to single-walled carbon nanotubes. No oxidized molecular species were found in two most abundant phospholipid classes – phosphatidylcholine and phosphatidylethanolamine. Peroxidation products were identified in three relatively minor classes of anionic phospholipids, cardiolipin, phosphatidylserine and phosphatidylinositol whereby oxygenation of polyunsaturated fatty acid residues also showed unusual substrate specificity. This non-random peroxidation coincided with the accumulation of apoptotic cells in the lung. A similar selective phospholipid peroxidation profile was detected upon incubation of a mixture of total lung lipids with H2O2/cytochrome c known to catalyze cardiolipin and phosphatidylserine peroxidation in apoptotic cells. The characterized specific phospholipid peroxidation signaling pathways indicate new approaches to the development of mitochondria targeted regulators of cardiolipin peroxidation to protect against deleterious effects of pro-apoptotic effects of single-walled carbon nanotubes in the lung. PMID:21800898

  19. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes.

    PubMed

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M; Hároz, Erik H; Doorn, Stephen K; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M; Adams, W Wade; Hauge, Robert H; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm(2)) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 10(6) nanotubes in a cross-sectional area of 1 μm(2). The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios.

  20. Atomistic finite element model for axial buckling of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Rouhi, S.

    2010-11-01

    An atomistic finite element model is developed to study the buckling behavior of single-walled carbon nanotubes with different boundary conditions. By treating nanotubes as space-frame structures, in which the discrete nature of nanotubes is preserved, they are modeled using three-dimensional elastic beam elements for the bonds and point mass elements for the atoms. The elastic moduli of the beam elements are determined via a linkage between molecular mechanics and structural mechanics. Based on this model, the critical compressive forces of single-walled carbon nanotubes with different boundary conditions, geometries as well as chiralities are obtained and then compared. It is indicated that at low aspect ratios, the critical buckling load of nanotubes decreases considerably with increasing aspect ratios, whereas at higher aspect ratios, buckling load slightly decreases as the aspect ratio increases. It is also indicated that increasing aspect ratio at a given radius results in the convergence of buckling envelops associated with armchair and zigzag nanotubes.

  1. Improving Dispersion of Single-Walled Carbon Nanotubes in a Polymer Matrix Using Specific Interactions

    SciTech Connect

    Rasheed, Asif; Dadmun, Mark D; Ivanov, Ilia N; Britt, Phillip F; Geohegan, David B

    2006-01-01

    A novel approach is presented to improve the dispersion of oxidized single-walled carbon nanotubes (SWNTs) in a copolymer matrix by tuning hydrogen-bonding interactions to enhance dispersion. Nanocomposites of single-walled carbon nanotubes and copolymers of styrene and vinyl phenol (PSVPh) with varying vinyl phenol content were produced and examined. The dispersion of the SWNT in the polymer matrix is quantified by optical microscopy and Raman spectroscopy. Raman spectroscopy is also used to investigate preferred interactions between the SWNTs and the copolymers via the shift in the D* Raman band of the SWNTs in the composites. All composites show regions of SWNT aggregates; however, the aggregate size varies with composition of the PSVPh copolymer and the amount of SWNT oxidation. Optimal dispersion of the SWNT is observed in PSVPh with 20% vinyl phenol and oxidized nanotubes, which correlates with spectroscopic evidence that indicates that this system also incorporates the most interactions between SWNT and polymer matrix. These results are in agreement with previous studies that indicate that optimizing the extent of specific interactions between a polymer matrix and nanoscale filler enables the efficient dispersion of the nanofillers.

  2. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M.; Hároz, Erik H.; Doorn, Stephen K.; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M.; Adams, W. Wade; Hauge, Robert H.; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm2) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 106 nanotubes in a cross-sectional area of 1 μm2. The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios.

  3. Structural stability of transparent conducting films assembled from length purified single-wall carbon nanotubes

    SciTech Connect

    J. M. Harris; G. R. S. Iyer; D. O. Simien; J. A. Fagan; J. Y. Huh; J. Y. Chung; S. D. Hudson; J. Obrzut; J. F. Douglas; C. M. Stafford; E. K. Hobbie

    2011-01-01

    Single-wall carbon nanotube (SWCNT) films show significant promise for transparent electronics applications that demand mechanical flexibility, but durability remains an outstanding issue. In this work, thin membranes of length purified single-wall carbon nanotubes (SWCNTs) are uniaxially and isotropically compressed by depositing them on prestrained polymer substrates. Upon release of the strain, the topography, microstructure, and conductivity of the films are characterized using a combination of optical/fluorescence microscopy, light scattering, force microscopy, electron microscopy, and impedance spectroscopy. Above a critical surface mass density, films assembled from nanotubes of well-defined length exhibit a strongly nonlinear mechanical response. The measured strain dependence reveals a dramatic softening that occurs through an alignment of the SWCNTs normal to the direction of prestrain, which at small strains is also apparent as an anisotropic increase in sheet resistance along the same direction. At higher strains, the membrane conductivities increase due to a compression-induced restoration of conductive pathways. Our measurements reveal the fundamental mode of elasto-plastic deformation in these films and suggest how it might be suppressed.

  4. Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells

    PubMed Central

    2011-01-01

    Herein we are the first to report that single-walled carbon nanotubes (SWCNTs) exhibit dual-phase regulation to Arabidopsis mesophyll cells exposed to different concentration of SWCNTs. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 h, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS) generation was measured. Partial protoplasts were stained with propidium iodide and 4'-6- diamidino-2-phenylindole, partial protoplasts were incubated with fluorescein isothiocyanate-labeled SWCNTs, and observed by fluorescence microscopy. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' necrosis and apoptosis. In conclusion, single walled carbon nanotubes can get through Arabidopsis mesophyll cell wall and membrane, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts such as low dose stimulating cell growth, and high dose inducing cells' ROS generation, necrosis or apoptosis. PMID:27502666

  5. Composite of single walled carbon nanotube and sulfosalicylic acid doped polyaniline: a thermoelectric material

    NASA Astrophysics Data System (ADS)

    Jana Chatterjee, Mukulika; Banerjee, Dipali; Chatterjee, Krishanu

    2016-08-01

    Nanocomposites containing single walled carbon nanotubes (SWCNTs) and highly ordered polyaniline (PANI) have been synthesized employing an in situ polymerization using different weight percentages of single-walled carbon nanotube (SWCNT) as template and aniline as a reactant. The composites show homogeneously dispersed SWCNTs which are uniformly coated with PANI through a strong interface interaction. Structural characterization shows that the PANI cultivated along the surface of the SWCNTs in an ordered manner during the SWCNT-directed polymerization process. Measurements at room temperature displayed a significant enhancement in both the electrical conductivity and thermoelectric power which could be attributed to the more ordered chain structures of the PANI on SWCNT. As a result, the power factor of the composite is improved which increases with temperature. At the same time, the measured value of thermal conductivity at room temperature being lowest among the reported values, has resulted in best ZT at room temperature. The lowest value of thermal conductivity is attributed to the large phonon scattering due to the introduction of nanointerfaces.

  6. Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery.

    PubMed

    Smith, Bryan Ronain; Ghosn, Eliver Eid Bou; Rallapalli, Harikrishna; Prescher, Jennifer A; Larson, Timothy; Herzenberg, Leonore A; Gambhir, Sanjiv Sam

    2014-06-01

    In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using 'bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6C(hi) monocytes (almost 100% uptake in Ly-6C(hi) monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.

  7. Biodurability of Single-Walled Carbon Nanotubes Depends on Surface Functionalization

    PubMed Central

    Liu, Xinyuan; Hurt, Robert H.; Kane, Agnes B.

    2010-01-01

    Recent research has led to increased concern about the potential adverse human health impacts of carbon nanotubes, and further work is needed to better characterize those risks and develop risk management strategies. One of the most important determinants of the chronic pathogenic potential of a respirable fiber is its biological durability, which affects the long-term dose retained in the lungs, or biopersistence. The present article characterizes the biodurability of single-walled carbon nanotubes using an in vitro assay simulating the phagolysosome. Biodurability is observed to depend on the chemistry of nanotube surface functionalization. Single-walled nanotubes with carboxylated surfaces are unique in their ability to undergo 90-day degradation in a phagolysosomal simulant leading to length reduction and accumulation of ultrafine solid carbonaceous debris. Unmodified, ozone-treated, and aryl-sulfonated tubes do not degrade under these conditions. We attribute the difference to the unique chemistry of acid carboxylation, which not only introduces COOH surface groups, but also causes collateral damage to the tubular graphenic backbone in the form of neighboring active sites that provide points of attack for further oxidative degradation. These results suggest the strategic use of surface carboxylation in nanotube applications where biodegradation may improve safety or add function. PMID:20352066

  8. Functionalization of single-walled carbon nanotubes regulates their effect on hemostasis

    NASA Astrophysics Data System (ADS)

    Sokolov, A. V.; Aseychev, A. V.; Kostevich, V. A.; Gusev, A. A.; Gusev, S. A.; Vlasova, I. I.

    2011-04-01

    Applications of single-walled carbon nanotubes (SWNTs) in medical field imply the use of drug-coupled carbon nanotubes as well as carbon nanotubes functionalized with different chemical groups that change nanotube surface properties and interactions between nanotubes and cells. Covalent attachment of polyethylene glycol (PEG) to carboxylated single-walled carbon nanotubes (c-SWNT) is known to prevent the nanotubes from interaction with macrophages. Here we characterized nanotube's ability to stimulate coagulation processes in platelet-poor plasma (PPP), and evaluated the effect of SWNTs on platelet aggregation in platelet-rich plasma (PRP). Our study showed that PEG-SWNT did not affect the rate of clotting in PPP, while c-SWNT shortened the clot formation time five times compared to the control PPP. Since c-SWNT failed to accelerate coagulation in plasma lacking coagulation factor XI, it may be suggested that c-SWNT affects the contact activation pathway. In PRP, platelets responded to both SWNT types with irreversible aggregation, as evidenced by changes in the aggregate mean radius. However, the rate of aggregation induced by c-SWNT was two times higher than it was with PEG-SWNT. Cytological analysis also showed that c-SWNT was two times more efficient when compared to PEG-SWNT in aggregating platelets in PRP. Taken together, our results show that functionalization of nanoparticles can diminish their negative influence on blood cells. As seen from our data, modification of c-SWNT with PEG, when only a one percent of carbon atoms is bound to polymer (70 wt %), decreased the nanotube-induced coagulation in PRP and repelled the accelerating effect on the coagulation in PPP. Thus, when functionalized SWNTs are used for administration into bloodstream of laboratory animals, their possible pro-coagulant and pro-aggregating properties must be taken into account.

  9. Development of novel single-wall carbon nanotube epoxy composite ply actuators

    NASA Astrophysics Data System (ADS)

    Yun, Yeo-Heung; Shanov, Vesselin; Schulz, Mark J.; Narasimhadevara, Suhasini; Subramaniam, Srinivas; Hurd, Douglas; Boerio, F. J.

    2005-12-01

    This paper describes a carbon nanotube epoxy ply material that has electrochemical actuation properties. The material was formed by dispersing single-wall carbon nanotubes in a solvent and then solution casting a thin paper using a mold and vacuum oven. In order to take advantage of the high elastic modulus of carbon nanotubes for actuation, epoxy as a chemically inert polymer is considered. An epoxy layer was cast on the surface of the nanotube paper to make a two-layer ply. A wet electrochemical actuator was formed by placing the nanotube epoxy ply in a 2 M NaCl electrolyte solution. Electrochemical impedance spectroscopy and cyclic voltammetry were carried out to characterize the electrochemical properties of the actuator. The voltage-current relationship and power to drive the actuator material were also determined. Compared to previous single-wall carbon nanotube buckypaper tape actuators, which had poor adhesion between the nanotubes and tape, and other nanotube-thermal plastic polymer actuators, which could not provide high strength, the epoxy based actuator has a higher elastic modulus and strength, which will be useful for future structural applications. This demonstrates that a polymer layer can reinforce nanotube paper, which is an important step in building a new structural material that actuates. Further work is under way to develop a solid electrolyte to allow dry actuation. Finally, these actuator plies will be laminated to build a carbon nanocomposite material. This smart structural material will have potential applications that range from use in robotic surgical tools to use as structures that change shape.

  10. Optical and electrical studies of single walled carbon nanotubes for infrared sensing and photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Omari, Mones A.

    Carbon nanotubes are emerging as highly promising opto-electro-mechanical device components essential for the development of a variety of hybrid opto-electronic, electro-mechanical and bio-medical technologies on the nanoscale and have been a subject of continued research. In particular, single-walled carbon nanotubes are predicted to exhibit strong light absorption induced by photon-assisted electronic transitions, free carrier and plasmonic-based absorption. Single-walled carbon nanotubes have been confirmed to exhibit a strong photoconduction response in the infrared range, which can provide many new opportunities in engineering nano-photovoltaic and optoelectronic devices. At the same time, the use of strong chemical reagents has been long considered as one of the key processing steps for the separation and purification of single-walled carbon nanotube post-synthesis. In this work, optically-induced voltage in carbon nanotube bundles and thin-films configured as two-terminal resistive elements and operating as junctionless photo-cells in the infrared range as well as the time-dependent wet-processing of HiPCo nanotubes in phosphoric acid and its effect on the structural, transport, infrared light absorption, and photoconduction characteristics were studied. As the photo-voltage generated is found to appear only for asymmetric and off-contact illuminations, the effect is explained based on a photo-generated heat flow model. The engineered cell prototypes were found to yield electrical powers of ˜ 30 pW while demonstrating improved conversion efficiency under high-flux illumination. The cell is also shown to act as an uncooled infrared sensor, with its dark-to-photocurrent ratio improving as temperature increases. The wet-processing of HiPCo nanotubes was done for a nominal time intervals of 1, 2 and 3 hours. The treatment was found to be a two-step process that initially results in the removal and partial replacement of most pre-existing C-O, O-H and CHx groups

  11. Stable single helical C- and I-chains inside single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yao, Z.; Liu, C. J.; Li, Y.; Jing, X. D.; Meng, F. S.; Zheng, S. P.; Zhao, X.; Li, J. H.; Qiu, Z. Y.; Yuan, Q.; Wang, W. X.; Bi, L.; Liu, H.; Zhang, Y. P.; Liu, B. B.

    2016-09-01

    The helicity of stable single helical carbon chains and iodine chains inside single-walled carbon nanotubes (SWCNTs) is studied by calculating the systematic van der Waals interaction energy. The results show that the optimal helical radius increases linearly with increasing tube radius, which produces a constant separation between the chain structure and the tube wall. The helical angle exhibits a ladder-like decrease with increasing tube radius, indicating that a large tube can produce a small helicity in the helical structures. Project supported by the National Basic Research Program of China (Grant No. 2011CB808200), the National Natural Science Foundation of China (Grant Nos. 11504150 and 51320105007), and the Cheung Kong Scholars Program of China.

  12. The effect of fibronectin on structural and biological properties of single walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Mottaghitalab, Fatemeh; Farokhi, Mehdi; Atyabi, Fatemeh; Omidvar, Ramin; Shokrgozar, Mohammad Ali; Sadeghizadeh, Majid

    2015-06-01

    Despite the attractive properties of carbon nanotubes (CNTs), cytoxicity and hydrophobicity are two main considerable features which limit their application in biomedical fields. It was well established that treating CNTs with extracellular matrix components could reduce these unfavourable characteristics. In an attempt to address these issues, fibronectin (FN) with different concentrations was loaded on single walled carbon nanotubes (SWCNTs) substrate. Scanning electron microscope, atomic force microscopy (AFM), contact angles and X-ray photoelectron spectroscopy (XPS) were preformed in order to characterize FN loaded SWCNTs substrates. According to XPS and AFM results, FN could interact with SWCNTs and for this, the hydrophilicity of SWCNTs was improved. Additionally, SWCNT modified with FN showed less cytotoxicity compared with neat SWCNT. Finally, FN was shown to act as an interesting extracellular component for enhancing the biological properties of SWCNT.

  13. High-sensitivity bolometers from self-oriented single-walled carbon nanotube composites.

    PubMed

    Vera-Reveles, Gustavo; Simmons, Trevor J; Bravo-Sánchez, Mariela; Vidal, M A; Navarro-Contreras, Hugo; González, Francisco J

    2011-08-01

    In this work, films of horizontally aligned single-walled carbon nanotubes were thermally and electrically characterized in order to determine the bolometric performance. An average thermal time constant of τ = 420 μs along with a temperature coefficient of resistance of TCR = -2.94% K(-1) were obtained. The maximum voltage responsivity and detectivity obtained were R(V) =230 V/W and D* = 1.22 × 10(8) cm Hz(1/2)/W, respectively. These values are higher than the maximum voltage responsivity (150 V/W) and maximum temperature coefficient of resistance (1.0% K(-1)) previously reported for carbon nanotube films at room temperature. The maximum detectivity was obtained at a frequency of operation of 1.25 kHz.

  14. Photon antibunching in single-walled carbon nanotubes at telecommunication wavelengths and room temperature

    SciTech Connect

    Endo, Takumi Ishi-Hayase, Junko; Maki, Hideyuki

    2015-03-16

    We investigated the photoluminescence of individual air-suspended single-walled carbon nanotubes (SWNTs) from 6 to 300 K. Time-resolved and antibunching measurements over the telecommunication wavelength range were performed using a superconducting single-photon detector. We detected moderate temperature independent antibunching behavior over the whole temperature range studied. To investigate the exciton dynamics, which is responsible for the antibunching behavior, we measured excitation-power and temperature dependence of the photoluminescence spectra and lifetime decay curves. These measurements suggested an exciton confinement effect that is likely caused by high-dielectric amorphous carbon surrounding the SWNTs. These results indicate that SWNTs are good candidates for light sources in quantum communication technologies operating in the telecommunication wavelength range and at room temperature.

  15. Fabrication and performance of contamination free individual single-walled carbon nanotube optical devices.

    PubMed

    Zhou, Yuxiu; Cheng, Rong; Liu, Jianqiang; Li, Tie

    2014-06-01

    Contamination free individual single-walled carbon nanotube (SWCNT) optical devices are fabricated using a hybrid method in the purpose of increase sensitivity as well as further understanding the sensing mechanism. The devices were tested in vacuum to avoid contamination. Three typical devices are discussed comparatively. Under infrared lamp illumination, photovoltaic and photoconductive properties are revealed in device A and B respectively, while device C shows no detectable signal. The photoresponse of device B reaches 108% at 78 K, much larger than that of horizontally aligned or network carbon nanotube devices, indicating priority of the individual nanotube device structure. Interestingly, the temperature characteristics of device A and B are just the opposite. The individual SWCNT devices hold promise in high performance and low cost optical sensors as well as nano-scale solar cells.

  16. Functionalized single walled carbon nanotubes as template for water storage device

    NASA Astrophysics Data System (ADS)

    Paul, Sanjib; Taraphder, Srabani

    2016-11-01

    Single walled carbon nanotubes, endohedrally functionalized with a protonated/unprotonated carboxylic acid group, are examined as potential templates for water storage using classical molecular dynamics simulation studies. Following a spontaneous entry of water molecules into the core of model functionalized carbon nanotubes (FCNTs), a large fraction of water molecules are found to be trapped inside FCNTs of lengths 50 and 100 Å. Only water molecules near the two open ends of the nanotube are exchanged with the bulk solvent. The residence times of water molecules inside FCNTs are investigated by varying the length of the tube, the length of suspended functional group and the protonation state of the carboxylic acid group. Favorable energetic interactions between the functional group and water, assisted by a substantial gain in rotational entropy, are found to compensate for the entropy loss resulting from restricted translational diffusion of trapped water molecules.

  17. DNA Linked To Single Wall Carbon Nanotubes: Covalent Versus Non-Covalent Approach

    NASA Astrophysics Data System (ADS)

    Chung, C.-L.; Nguyen, K.; Lyonnais, S.; Streiff, S.; Campidelli, S.; Goux-Capes, L.; Bourgoin, J.-P.; Filoramo, A.

    2008-10-01

    Nanometer-scale structures represent a novel and intriguing field, where scientists and engineers manipulate materials at the atomic and molecular scale levels to produce innovative materials. Carbon nanotubes constitute a relatively new class of materials exhibiting exceptional mechanical and electronic properties and were found to be promising candidates for molecular electronics, sensing or biomedical applications. Considering the bottom-up strategy in nanotechnology, the combination of the recognition properties of DNA with the electronic properties of single walled carbon nanotubes (SWNTs) seems to be a promising approach for the future of electronics. With the aim to assemble DNA with SWNTs, two complementary strategies have been envisioned: the covalent linkage of DNA on carboxylic groups of SWNTs under classical coupling condition and the non-covalent approach based on biotin-streptavidin molecular recognition properties. Here, we present and compare the results that we obtained with these two different methods; we want to objectively show the advantages and disadvantages of each approach.

  18. On the linear representations of the symmetry groups of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cotfas, Nicolae

    2006-08-01

    The positions of atoms forming a carbon nanotube are usually described by using a system of generators of the symmetry group. Each atomic position corresponds to an element of the set {\\bb Z}\\times \\{0,1,\\ldots,n\\} \\times \\{0,1\\} , where n depends on the considered nanotube. We obtain an alternative, rather different description by starting from a three-axes description of the honeycomb lattice. In our mathematical model, which is a factor space defined by an equivalence relation in the set \\{(v_0,v_1,v_2)\\in {\\bb Z}^3\\mid v_0+v_1+v_2\\in \\{0,1\\}\\} , the neighbours of an atomic position can be described in a simpler way, and the mathematical objects with geometric or physical significance have a simpler and more symmetric form. We present some results concerning the linear representations of the symmetry groups of single-wall carbon nanotubes in order to illustrate the proposed approach.

  19. Enzymatic formation of carbohydrate rings catalyzed by single-walled carbon nanotubes.

    PubMed

    Hyun, Moon Seop; Park, Jong Pil; Seo, Dongkyun; Chang, Sung-Jin; Lee, Seok Jae; Lee, Sang Yup; Kwak, Kyungwon; Park, Tae Jung

    2016-05-01

    Macrocyclic carbohydrate rings were formed via enzymatic reactions around single-walled carbon nanotubes (SWNTs) as a catalyst. Cyclodextrin glucanotransferase, starch substrate and SWNTs were reacted in buffer solution to yield cyclodextrin (CD) rings wrapped around individual SWNTs. Atomic force microscopy showed the resulting complexes to be rings of 12-50 nm in diameter, which were highly soluble and dispersed in aqueous solution. They were further characterized by Raman and Fourier transform infrared spectroscopy and molecular simulation using density functional theory calculation. In the absence of SWNT, hydrogen bonding between glucose units determines the structure of maltose (the precursor of CD) and produces the curvature along the glucose chain. Wrapping SWNT along the short axis was preferred with curvature in the presence of SWNTs and with the hydrophobic interactions between the SWNTs and CD molecules. This synthetic approach may be useful for the functionalization of carbon nanotubes for development of nanostructures.

  20. Adsorption equilibrium of organic vapors on single-walled carbon nanotubes

    USGS Publications Warehouse

    Agnihotri, S.; Rood, M.J.; Rostam-Abadi, M.

    2005-01-01

    Gravimetric techniques were employed to determine the adsorption capacities of commercially available purified electric arc and HiPco single-walled carbon nanotubes (SWNTs) for organic compounds (toluene, methyl ethyl ketone (MEK), hexane and cyclohexane) at relative pressures, p/p0, ranging from 1 ?? 10-4 to 0.95 and at isothermal conditions of 25, 37 and 50 ??C. The isotherms displayed both type I and type II characteristics. Adsorption isotherm modeling showed that SWNTs are heterogeneous adsorbents, and the Freundlich equation best describes the interaction between organic molecules and SWNTs. The heats of adsorption were 1-4 times the heats of vaporization, which is typical for physical adsorption of organic vapors on porous carbons. ?? 2005 Elsevier Ltd. All rights reserved.

  1. Multi-Fractal Hierarchy of Single-Walled Carbon Nanotube Hydrophobic Coatings

    PubMed Central

    De Nicola, Francesco; Castrucci, Paola; Scarselli, Manuela; Nanni, Francesca; Cacciotti, Ilaria; De Crescenzi, Maurizio

    2015-01-01

    A hierarchical structure is an assembly with a multi-scale morphology and with a large and accessible surface area. Recent advances in nanomaterial science have made increasingly possible the design of hierarchical surfaces with specific and tunable properties. Here, we report the fractal analysis of hierarchical single-walled carbon nanotube (SWCNT) films realized by a simple, rapid, reproducible, and inexpensive filtration process from an aqueous dispersion, then deposited by drytransfer printing method on several substrates, at room temperature. Furthermore, by varying the thickness of carbon nanotube random networks, it is possible tailoring their wettability due to capillary phenomena in the porous films. Moreover, in order to describe the wetting properties of such surfaces, we introduce a two-dimensional extension of the Wenzel-Cassie-Baxter theory. The hierarchical surface roughness of SWCNT coatings coupled with their exceptional and tunable optical and electrical properties provide an ideal hydrophobic composite surface for a new class of optoelectronic and nanofluidic devices. PMID:25716718

  2. Grafting of Chitosan and Chitosantrimethoxylsilylpropyl Methacrylate on Single Walled Carbon Nanotubes-Synthesis and Characterization.

    PubMed

    Carson, Laura; Kelly-Brown, Cordella; Stewart, Melisa; Oki, Aderemi; Regisford, Gloria; Stone, Julia; Traisawatwong, Pasakorn; Durand-Rougely, Clarissa; Luo, Zhiping

    2010-09-01

    Acid functionalized single walled carbon nanotubes (CNTs) were grafted to chitosan by first reacting the oxidized CNTs with thionyl chloride to form acyl-chlorinated CNTs. This product was subsequently dispersed in chitosan and covalently grafted to form CNT-chitosan. CNT-chitosan was further grafted onto 3-trimethoxysilylpropyl methacrylate by free radical polymerization conditions, to yield CNT-g-chitosan-g-3-trimethoxysilylpropyl methacrylate (TMSPM), hereafter referred to as CNT-chitosan-3-TMSPM. These composites were characterized by Fourier Transform Infrared Resonance Spectroscopy (FTIR), carbon-13 nuclear magnetic resonance ((13)C NMR), Thermogravimetric Analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composite showed improved thermal stability and could be of great potential use in bone tissue engineering.

  3. Compressive characteristics of single walled carbon nanotube with water interactions investigated by using molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Wong, C. H.; Vijayaraghavan, V.

    2014-01-01

    The elastic properties of single walled carbon nanotube (SWCNT) with surrounding water interactions are studied using molecular dynamics simulation technique. The compressive loading characteristic of carbon nanotubes (CNTs) in a fluidic medium such as water is critical for its role in determining the lifetime and stability of CNT based nano-fluidic devices. In this paper, we conducted a comprehensive analysis on the effect of geometry, chirality and density of encapsulated water on the elastic properties of SWCNT. Our studies show that defect density and distribution can strongly impact the compressive resistance of SWCNTs in water. Further studies were conducted on capped SWCNTs with varying densities of encapsulated water, which is necessary to understand the strength of CNT as a potential drug carrier. The results obtained from this paper will help determining the potential applications of CNTs in the field of nano-electromechanical systems (NEMS) such as nano-biological and nano-fluidic devices.

  4. Magnetic Property Measurements on Single Wall Carbon Nanotube-Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Sun, Keun J.; Wincheski, Russell A.; Park, Cheol

    2008-01-01

    Temperature and magnetic field dependent magnetization measurements were performed on polyimide nanocomposite samples, synthesized with various weight percentages of single wall carbon nanotubes. It was found that the magnetization of the composite, normalized to the mass of nanotube material in the sample, decreased with increasing weight percentage of nanotubes. It is possible that the interfacial coupling between the carbon nanotube (CNT) fillers and the polyimide matrix promotes the diamagnetic response from CNTs and reduces the total magnetization of the composite. The coercivity of the samples, believed to originate from the residual magnetic catalyst particles, was enhanced and had a stronger temperature dependence as a result of the composite synthesis. These changes in magnetic properties can form the basis of a new approach to investigate the interfacial properties in the CNT nanocomposites through magnetic property measurements.

  5. Zipping, entanglement, and the elastic modulus of aligned single-walled carbon nanotube films

    PubMed Central

    Won, Yoonjin; Gao, Yuan; Panzer, Matthew A.; Xiang, Rong; Maruyama, Shigeo; Kenny, Thomas W.; Cai, Wei; Goodson, Kenneth E.

    2013-01-01

    Reliably routing heat to and from conversion materials is a daunting challenge for a variety of innovative energy technologies––from thermal solar to automotive waste heat recovery systems––whose efficiencies degrade due to massive thermomechanical stresses at interfaces. This problem may soon be addressed by adhesives based on vertically aligned carbon nanotubes, which promise the revolutionary combination of high through-plane thermal conductivity and vanishing in-plane mechanical stiffness. Here, we report the data for the in-plane modulus of aligned single-walled carbon nanotube films using a microfabricated resonator method. Molecular simulations and electron microscopy identify the nanoscale mechanisms responsible for this property. The zipping and unzipping of adjacent nanotubes and the degree of alignment and entanglement are shown to govern the spatially varying local modulus, thereby providing the route to engineered materials with outstanding combinations of mechanical and thermal properties. PMID:24309375

  6. In vivo MRI of single-wall carbon nanohorns through magnetite nanoparticle attachment

    NASA Astrophysics Data System (ADS)

    Miyawaki, Jin; Yudasaka, Masako; Imai, Hideto; Yorimitsu, Hideki; Isobe, Hiroyuki; Nakamura, Eiichi; Iijima, Sumio

    2006-03-01

    Superparamagnetic magnetite (SPM) is used as a contrast agent in magnetic resonance imaging (MRI). Thus, the SPM-attachment to carbon nanotubes (CNTs) will enable to visualize motional behaviors of CNTs in the living body through MRI. We found that the strong attachment of the SPM nanoparticles (ca. 6 nm size) to one type of CNTs, single-wall carbon nanohorns (SWNHs), could be achieved through a deposition of iron acetate clusters on SWNHs in ethanol at room temperature, followed by heat-treatment in Ar. In vivo MRI visualized that the SWNHs attached with the SPM nanoparticles accumulated in several organs of mice when injected into mice via tail veins. This simple method for the SPM-attaching on CNTs would facilitate the toxicity assessment of CNTs and the applications of CNTs in bioscience and biotechnology.

  7. Adsorption behavior of ternary mixtures of noble gases inside single-walled carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Foroutan, Masumeh; Nasrabadi, Amir Taghavi

    2010-09-01

    In order to study the gas-storage and gas-filtering capability of carbon nanotube (CNT) bundles simultaneously, we considered the adsorption behavior of a ternary mixture of noble gases, including Argon (Ar), Krypton (Kr), and Xenon (Xe), i.e., Ar-Kr-Xe mixture, on (10, 10) single-walled carbon nanotube (SWCNT) bundles. Molecular dynamics (MD) simulations at different temperatures of (75, 100, 150, 200, 250, and 300) K were performed, and adsorption energies, self-diffusion coefficients, activation energies, and radial distribution functions (RDFs) were computed to analyze the thermodynamics, transport and structural properties of the adsorption systems. It is observed that the SWCNT bundles have larger contents of heavier noble gases compared to the lighter ones. This interesting behavior of SWCNT bundles makes them proper candidates for gas-storage and gas molecular-sieving processes.

  8. Low-temperature magnetoresistance of individual single-walled carbon nanotubes: A numerical study

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenhua; Peng, Jingcui; Huang, Xiaoyi; Zhang, Hua

    2002-08-01

    The low-temperature magnetoresistance induced by an axial magnetic field in individual single-walled carbon nanotubes (SWNTs) is studied numerically based on Boltzmann transport equation and π electronic energy dispersion relations for individual SWNTs as well as taking one-dimensional weak localization (WL) into account. It is shown that the Altshuler-Aronov-Spivak effect related to WL is much weaker in individual SWNTs than in individual multiwalled carbon nanotubes, whereas the Aharonov-Bohm (AB) effect related to tubular energy band structure is stronger in individual SWNTs when the conducting electrons occupy lower energy levels, but this effect weakens rapidly as conducting electron energy increases. This suggests that only the AB effect can be observed remarkably in the states of the conducting electrons with lower energy.

  9. A parametric study of single-wall carbon nanotube growth by laser ablation

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram; Holmes, William A.; Nikolaev, Pavel; Hadjiev, Victor G.; Scott, Carl D.

    2004-01-01

    Results of a parametric study of carbon nanotube production by the double-pulse laser oven process are presented. The effect of various operating parameters on the production of single-wall carbon nanotubes (SWCNTs) is estimated by characterizing the nanotube material using analytical techniques, including scanning electron microscopy, transmission electron microscopy, thermo gravimetric analysis and Raman spectroscopy. The study included changing the sequence of the laser pulses, laser energy, pulse separation, type of buffer gas used, operating pressure, flow rate, inner tube diameter, as well as its material, and oven temperature. It was found that the material quality and quantity improve with deviation from normal operation parameters such as laser energy density higher than 1.5 J/cm2, pressure lower than 67 kPa, and flow rates higher than 100 sccm. Use of helium produced mainly small diameter tubes and a lower yield. The diameter of SWCNTs decreases with decreasing oven temperature and lower flow rates.

  10. Energy Band Gap Study of Semiconducting Single Walled Carbon Nanotube Bundle

    NASA Technical Reports Server (NTRS)

    Elkadi, Asmaa; Decrossas, Emmanuel; El-Ghazaly, Samir

    2013-01-01

    The electronic properties of multiple semiconducting single walled carbon nanotubes (s-SWCNTs) considering various distribution inside a bundle are studied. The model derived from the proposed analytical potential function of the electron density for an individual s-SWCNT is general and can be easily applied to multiple nanotubes. This work demonstrates that regardless the number of carbon nanotubes, the strong coupling occurring between the closest neighbours reduces the energy band gap of the bundle by 10%. As expected, the coupling is strongly dependent on the distance separating the s-SWCNTs. In addition, based on the developed model, it is proposed to enhance this coupling effect by applying an electric field across the bundle to significantly reduce the energy band gap of the bundle by 20%.

  11. Energy Band Gap Study of Semiconducting Single Walled Carbon Nanotube Bundle

    NASA Technical Reports Server (NTRS)

    Elkadi, Asmaa; Decrossas, Emmanuel; El-Ghazaly, Samir

    2013-01-01

    The electronic properties of multiple semiconducting single walled carbon nanotubes (s-SWCNTs) considering various distribution inside a bundle are studied. The model derived from the proposed analytical potential function of electron density for na individual s-SWCNT is general and can be easily applied to multiple nanotubes. This work demonstrates that regardless the number of carbon nanotubes, the strong coupling occurring between the closet neighbors reduces the energy band gap of the bundle by 10%. As expected, the coupling is strongly dependent on the distance separating the s-SWCNTs. In addition, based on the developed model, it is proposed to enhance this coupling effect by applying an electric field across the bundle to significantly reduce the energy band gap of the bundle by 20%.

  12. Stable configurations of C20 and C28 encapsulated in single wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Pan, Z. Y.; Wang, Y. X.; Zhu, J.; Liu, T. J.; Jiang, X. M.

    2006-04-01

    The stable configurations of small fullerenes (C20 and C28) encapsulated inside single wall carbon nanotubes (SWNTs) of different diameters were investigated by molecular dynamics simulations. The interactions between carbon atoms were described by a combination of the many-body Brenner potential with the Lennard-Jones (LJ) potential. We observed that the filling of small fullerenes into nanotubes with diameters larger than 10.85 Å ((8, 8) SWNT) is an exothermic process. During the annealing process the fullerenes arrange themselves into complex phases, which may be one-(chain), two-(zigzag) or three-dimensional, depending on the tube diameter. This tube size dependence is very similar to that of C60, which has been experimentally observed. A comparison with the prediction of the hard-sphere model also finds a satisfactory level of consistency, indicating the dense packing nature of fullerene configurations in SWNTs.

  13. Electrochemical Investigation of Adsorption of Single-Wall Carbon Nanotubes at a Liquid/Liquid Interface.

    PubMed

    Rabiu, Aminu K; Toth, Peter S; Rodgers, Andrew N J; Dryfe, Robert A W

    2017-02-01

    There is much interest in understanding the interfacial properties of carbon nanotubes, particularly at water/oil interfaces. Here, the adsorption of single-wall carbon nanotubes (SWCNTs) at the water/1,2-dichloroethane (DCE) interface, and the subsequent investigation of the influence of the adsorbed nanotube layer on interfacial ion transfer, is studied by using the voltammetric transfer of tetramethylammonium (TMA(+)) and hexafluorophosphate (PF6(-)) as probe ions. The presence of the interfacial SWCNT layer significantly suppresses the transfer of both ions across the interface, with a greater degree of selectivity towards the PF6(-) ion. This effect was attributed both to the partial blocking of the interface by the SWCNTs and to the potential dependant adsorption of background electrolyte ions on the surface of the SWCNTs, as confirmed by X-ray photoelectron spectroscopy, which is caused by an electrostatic interaction between the interfacial SWCNTs and the transferring ion.

  14. Grafting of Chitosan and Chitosantrimethoxylsilylpropyl Methacrylate on Single Walled Carbon Nanotubes-Synthesis and Characterization

    PubMed Central

    Carson, Laura; Kelly-Brown, Cordella; Stewart, Melisa; Oki, Aderemi; Regisford, Gloria; Stone, Julia; Traisawatwong, Pasakorn; Durand-Rougely, Clarissa; Luo, Zhiping

    2011-01-01

    Acid functionalized single walled carbon nanotubes (CNTs) were grafted to chitosan by first reacting the oxidized CNTs with thionyl chloride to form acyl-chlorinated CNTs. This product was subsequently dispersed in chitosan and covalently grafted to form CNT-chitosan. CNT-chitosan was further grafted onto 3-trimethoxysilylpropyl methacrylate by free radical polymerization conditions, to yield CNT-g-chitosan-g-3-trimethoxysilylpropyl methacrylate (TMSPM), hereafter referred to as CNT-chitosan-3-TMSPM. These composites were characterized by Fourier Transform Infrared Resonance Spectroscopy (FTIR), carbon-13 nuclear magnetic resonance (13C NMR), Thermogravimetric Analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composite showed improved thermal stability and could be of great potential use in bone tissue engineering. PMID:21765959

  15. Conjugated polymer-assisted dispersion of single-wall carbon nanotubes: the power of polymer wrapping.

    PubMed

    Samanta, Suman Kalyan; Fritsch, Martin; Scherf, Ullrich; Gomulya, Widianta; Bisri, Satria Zulkarnaen; Loi, Maria Antonietta

    2014-08-19

    The future application of single-walled carbon nanotubes (SWNTs) in electronic (nano)devices is closely coupled to the availability of pure, semiconducting SWNTs and preferably, their defined positioning on suited substrates. Commercial carbon nanotube raw mixtures contain metallic as well as semiconducting tubes of different diameter and chirality. Although many techniques such as density gradient ultracentrifugation, dielectrophoresis, and dispersion by surfactants or polar biopolymers have been developed, so-called conjugated polymer wrapping is one of the most promising and powerful purification and discrimination strategies. The procedure involves debundling and dispersion of SWNTs by wrapping semiflexible conjugated polymers, such as poly(9,9-dialkylfluorene)s (PFx) or regioregular poly(3-alkylthiophene)s (P3AT), around the SWNTs, and is accompanied by SWNT discrimination by diameter and chirality. Thereby, the π-conjugated backbone of the conjugated polymers interacts with the two-dimensional, graphene-like π-electron surface of the nanotubes and the solubilizing alkyl side chains of optimal length support debundling and dispersion in organic solvents. Careful structural design of the conjugated polymers allows for a selective and preferential dispersion of both small and large diameter SWNTs or SWNTs of specific chirality. As an example, with polyfluorenes as dispersing agents, it was shown that alkyl chain length of eight carbons are favored for the dispersion of SWNTs with diameters of 0.8-1.2 nm and longer alkyls with 12-15 carbons can efficiently interact with nanotubes of increased diameter up to 1.5 nm. Polar side chains at the PF backbone produce dispersions with increased SWNT concentration but, unfortunately, cause reduction in selectivity. The selectivity of the dispersion process can be monitored by a combination of absorption, photoluminescence, and photoluminescence excitation spectroscopy, allowing identification of nanotubes with specific

  16. Separation of Single-Walled Carbon Nanotubes with DEP-FFF

    NASA Technical Reports Server (NTRS)

    Schmidt, Howard K.; Peng, Haiqing; Alvarez, Noe; Mendes, Manuel; Pasquali, Matteo

    2011-01-01

    A process using a modified dielectrophoresis device separates single-walled carbon nanotubes (SWNTs) according to their polarizability in electric fields. This depends on the size and dielectric constant of individual nanotubes and easily separates metallic from semiconducting nanotubes. Separation by length has also been demonstrated. Partial separation (enrichment) according to bandgap (which is linked to polarizability) has also been shown and can be improved to full separation of individual types of semiconducting SWNTs with better control over operational parameters and the length of SWNT starting material. This process and device can be scaled affordably to generate useful amounts of semiconducting SWNTs for electronic device development and production. In this study, a flow injection dielectrophoresis technique was used with a modified dielectrophoresis device. The length, width, and height of the modified chamber were 28, 2.5, and 0.025 cm, respectively. On the bottom of the chamber, there are two arrays of 50-m-wide, 2-m-thick gold electrodes, which are connected to an AC voltage generator and are alternately arranged so that every electrode is adjacent to two electrodes of the opposite polar. There is an additional plate electrode on the top of the chamber that is negatively biased. During the experiment, a syringe pump constantly pumps in the mobile phase, 1-percent sodium dodecylbenzene sulfonate (SDBS) solution, into the chamber. The frequency and voltage are set to 1 MHz and 10 V peak-to-peak, respectively. About 150 micro-L of SWNTs in 1- percent SDBS decanted solution are injected to the mobile phase through a septum near the entrance of the chamber. The flow rate of the mobile phase is set to 0.02 cu cm/min. The injected SWNTs sample flows through the chamber before it is lead into a fluorescence flow-through cell and collected for further analysis. The flow-through cell has three windows, thus allowing the fluorometer to collect fluorescence

  17. Electronic properties of optically transparent single-walled carbon nanotube films

    NASA Astrophysics Data System (ADS)

    Hecht, David Samuel

    Single-walled carbon nanotube (SWNT) films of various densities were fabricated and the optoelectronic properties studied. Several deposition techniques were developed, including filtration, stamping, self-assembly, spraying, and slot coating. Film conductivity was studied as a function of several parameters. At sub-monolayer densities, close to the percolation threshold, the film conductance follows the expected 2D percolation behavior. For films just thicker than a monolayer, the conductivity weakly increases up to a critical thickness, due to interlayer tube coupling. The frequency dependence of the conductivity follows the ac universality power law predicted for disordered systems. Due to the large intertube barriers (relative to the intratube resistance), the film conductivity increases as a power law in the constituent tube length. DC conductivities up to 2400 S/cm were measured, and increased to 6000 S/cm upon exposure to various dopants; however the binding is not stable at room temperature. The overall electrical stability of SWNT films is considered under various conditions. Nanotube films thinner than 100 nm are transparent in the visible and infrared spectrum, with the transmission limited by absorption, rather than by reflection. The visible spectrum is relatively featureless, apart from a weak interband transition at 700 nm; therefore, the films have a neutral, "gray" color. The large ratio of DC to optical conductivity make SWNT films useful for several applications including displays, solar cells, and touch screens. A prototype organic solar cell using a SWNT anode as shown to have efficiencies comparable to cells using an indium tin oxide anode; integration with a metallic grid was demonstrated. Films were coated onto fabric and shown to impart electrical conductivity to the fabric. Films of various densities were fabricated as both the gate and the conducting channel of a field effect transistor (FET), making the first transparent and flexible

  18. Effects of single-walled carbon nanotubes on the bioavailability of PCBs in field-contaminated sediments

    EPA Science Inventory

    Adsorption of hydrophobic organic contaminants (HOCs) to black carbon is a well studied phenomenon. One emerging class of engineered black carbon materials are single-walled carbon nanotubes (SWNT). Little research has investigated the potential of SWNT to adsorb and sequester HO...

  19. Mechanism of Synthesis of Ultra-Long Single Wall Carbon Nanotubes in Arc Discharge Plasma

    SciTech Connect

    Keidar, Michael

    2013-06-23

    In this project fundamental issues related to synthesis of single wall carbon nanotubes (SWNTs), which is relationship between plasma parameters and SWNT characteristics were investigated. Given that among plasma-based techniques arc discharge stands out as very advantageous in several ways (fewer defects, high flexibility, longer lifetime) this techniques warrants attention from the plasma physics and plasma technology standpoint. Both experimental and theoretical investigations of the plasma and SWNTs synthesis were conducted. Experimental efforts focused on plasma diagnostics, measurements of nanostructures parameters, and nanoparticle characterization. Theoretical efforts focused to focus on multi-dimensional modeling of the arc discharge and single wall nanotube synthesis in arc plasmas. It was demonstrated in experiment and theoretically that controlling plasma parameters can affect nanostucture synthesis altering SWNT properties (length and diameter) and leading to synthesis of new structures such as a few-layer graphene. Among clearly identified parameters affecting synthesis are magnetic and electric fields. Knowledge of the plasma parameters and discharge characteristics is crucial for ability to control synthesis process by virtue of both magnetic and electric fields. New graduate course on plasma engineering was introduced into curriculum. 3 undergraduate students were attracted to the project and 3 graduate students (two are female) were involved in the project. Undergraduate student from Historically Black University was attracted and participated in the project during Summer 2010.

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

    NASA Astrophysics Data System (ADS)

    Han, Yang; Hu, Ting; Dong, Jinming

    2013-01-01

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

  1. Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

    SciTech Connect

    Xie, Xu; Islam, Ahmad E.; Seabron, Eric; Dunham, Simon N.; Du, Frank; Lin, Jonathan; Wilson, William L.; Rogers, John A.; Wahab, Muhammad A.; Alam, Muhammad A.; Li, Yuhang; Tomic, Bojan; Huang, Jiyuan; Burns, Branden; Song, Jizhou; Huang, Yonggang

    2015-04-07

    Aligned arrays of semiconducting single-walled carbon nanotubes (s-SWNTs) represent ideal configurations for use of this class of material in high performance electronics. Development of means for removing the metallic SWNTs (m-SWNTs) in as-grown arrays represents an essential challenge. Here, we introduce a simple scheme that achieves this type of purification using direct, selective current injection through interdigitated electrodes into the m-SWNTs, to allow their complete removal using processes of thermocapillarity and dry etching. Experiments and numerical simulations establish the fundamental aspects that lead to selectivity in this process, thereby setting design rules for optimization. Single-step purification of arrays that include thousands of SWNTs demonstrates the effectiveness and simplicity of the procedures. The result is a practical route to large-area aligned arrays of purely s-SWNTs with low-cost experimental setups.

  2. Efficient separation of semiconducting single-wall carbon nanotubes by surfactant-composition gradient in gel filtration

    NASA Astrophysics Data System (ADS)

    Thendie, Boanerges; Omachi, Haruka; Miyata, Yasumitsu; Shinohara, Hisanori

    2017-01-01

    Gel filtration is a powerful method of separating and purifying semiconducting single-wall carbon nanotubes (s-SWCNTs) from their metallic (m-) counterpart. However, a small amount of m-SWCNTs usually remains, thus reducing the purity of the s-SWCNTs obtained. We have investigated the effect of elution with a gradient concentration of the surfactant on the separation and purity of s-SWCNTs. By utilizing the controlled low-gradient elution (CLGE) that we have developed, the purity of s-SWCNTs is improved to 94% from the 90% obtained with the conventional separation. Furthermore, CLGE simultaneously allows diameter-based separation of small-diameter s-SWCNTs, which indicates a promising utilization of CLGE for s-SWCNT separation.

  3. Single-walled carbon nanotube-based polymer monoliths for the enantioselective nano-liquid chromatographic separation of racemic pharmaceuticals.

    PubMed

    Ahmed, Marwa; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Su, Dawei; Wang, Guoxiu; Ostrikov, Kostya Ken; Ghanem, Ashraf

    2014-09-19

    Single-walled carbon nanotubes were encapsulated into different polymer-based monolithic backbones. The polymer monoliths were prepared via the copolymerization of 20% monomers, glycidyl methacrylate, 20% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) or 16.4% monomers (16% butyl methacrylate, 0.4% sulfopropyl methacrylate), 23.6% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) along with 6% single-walled carbon nanotubes aqueous suspension. The effect of single-walled carbon nanotubes on the chiral separation of twelve classes of pharmaceutical racemates namely; α- and β-blockers, antiinflammatory drugs, antifungal drugs, dopamine antagonists, norepinephrine-dopamine reuptake inhibitors, catecholamines, sedative hypnotics, diuretics, antihistaminics, anticancer drugs and antiarrhythmic drugs was investigated. The enantioselective separation was carried out under multimodal elution to explore the chiral recognition capabilities of single-walled carbon nanotubes using reversed phase, polar organic and normal phase chromatographic conditions using nano-liquid chromatography. Baseline separation was achieved for celiprolol, chlorpheniramine, etozoline, nomifensine and sulconazole under multimodal elution conditions. Satisfactory repeatability was achieved through run-to-run, column-to-column and batch-to-batch investigations. Our findings demonstrate that single-walled carbon nanotubes represent a promising stationary phase for the chiral separation and may open the field for a new class of chiral selectors.

  4. Templated Synthesis of Single-Walled Carbon Nanotubes with Specific Structure.

    PubMed

    Yang, Feng; Wang, Xiao; Li, Meihui; Liu, Xiyan; Zhao, Xiulan; Zhang, Daqi; Zhang, Yan; Yang, Juan; Li, Yan

    2016-04-19

    Single-walled carbon nanotubes (SWNTs) have shown great potential in various applications attributed to their unique structure-dependent properties. Therefore, the controlled preparation of chemically and structurally pristine SWNTs is a crucial issue for their advanced applications (e.g., nanoelectronics) and has been a great challenge for two decades. Epitaxial growth from well-defined seeds has been shown to be a promising strategy to control the structure of SWNTs. Segments of carbon nanotubes, including short pipes from cutting of preformed nanotubes and caps from opening of fullerenes or cyclodehydrogenation of polycyclic hydrocarbon precursors, have been used as the seeds to grow SWNTs. Single-chirality SWNTs were obtained with both presorted chirality-pure SWNT segments and end caps obtained from polycyclic hydrocarbon molecules with designed structure. The main challenges of nanocarbon-segment-seeded processes are the stability of the seeds, yield, and efficiency. Catalyst-mediated SWNT growth is believed to be more efficient. The composition and morphology of the catalyst nanoparticles have been widely reported to affect the chirality distribution of SWNTs. However, chirality-specific SWNT growth is hard to achieve by alternating catalysts. The specificity of enzyme-catalyzed reactions brings us an awareness of the essentiality of a unique catalyst structure for the chirality-selective growth of SWNTs. Only catalysts with the desired atomic arrangements in their crystal planes can act as structural templates for chirality-specific growth of SWNTs. We have developed a new family of catalysts, tungsten-based intermetallic compounds, which have high melting points and very special crystal structures, to facilitate the growth of SWNTs with designed chirality. By the use of W6Co7 catalysts, (12,6) SWNTs were directly grown with purity higher than 92%. Both high-resolution transmission electron microscopy measurements and density functional theory simulations

  5. Charge Manipulation in Molecules Encapsulated Inside Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Yanagi, Kazuhiro; Moriya, Rieko; Cuong, Nguyen Thanh; Otani, Minoru; Okada, Susumu

    2013-02-01

    We report clear experimental evidence for the charge manipulation of molecules encapsulated inside single-wall carbon nanotubes (SWCNTs) using electrochemical doping techniques. We encapsulated β-carotene (Car) inside SWCNTs and clarified electrochemical doping characteristics of their Raman spectra. C=C streching modes of encapsulated Car and a G band of SWCNTs showed clearly different doping behaviors as the electrochemical potentials were shifted. Electron extraction from encapsulated Car was clearly achieved. However, electrochemical characteristics of Car inside SWCNTs and doping mechanisms elucidated by calculations based on density-functional theory indicate the difficulty of charge manipulation of molecules inside SWCNTs due to the presence of strong on-site Coulomb repulsion energy at the molecules.

  6. Charge manipulation in molecules encapsulated inside single-wall carbon nanotubes.

    PubMed

    Yanagi, Kazuhiro; Moriya, Rieko; Cuong, Nguyen Thanh; Otani, Minoru; Okada, Susumu

    2013-02-22

    We report clear experimental evidence for the charge manipulation of molecules encapsulated inside single-wall carbon nanotubes (SWCNTs) using electrochemical doping techniques. We encapsulated β-carotene (Car) inside SWCNTs and clarified electrochemical doping characteristics of their Raman spectra. C=C streching modes of encapsulated Car and a G band of SWCNTs showed clearly different doping behaviors as the electrochemical potentials were shifted. Electron extraction from encapsulated Car was clearly achieved. However, electrochemical characteristics of Car inside SWCNTs and doping mechanisms elucidated by calculations based on density-functional theory indicate the difficulty of charge manipulation of molecules inside SWCNTs due to the presence of strong on-site Coulomb repulsion energy at the molecules.

  7. Multiple helical configuration and quantity threshold of graphene nanoribbons inside a single-walled carbon nanotube

    PubMed Central

    Li, Yifan; Chen, Wei; Ren, Hongru; Zhou, Xuyan; Li, Hui

    2015-01-01

    Molecular dynamics simulation has been carried out to explore the configuration and quantity threshold of multiple graphene nanoribbons (GNRs) in single-walled carbon nanotube (SWCNT). The simulation results showed that several GNRs tangled together to form a perfect spiral structure to maximize the π-π stacking area when filling inside SWCNT. The formation of multiple helical configuration is influenced by the combined effect of structure stability, initial arrangement and tube space, meanwhile its forming time is related to helical angle. The simulated threshold of GNRs in SWCNT decreases with GNR width but increases with SWCNT diameter, and two formulas have come up in this study to estimate the quantity threshold for GNRs. It has been found that multilayered graphite is hard to be stripped in SWCNT because the special helical configuration with incompletely separated GNRs is metastable. This work provides a possibility to control the configuration of GNR@SWCNT. PMID:26374276

  8. Selective interactions of sugar-functionalized single-walled carbon nanotubes with Bacillus spores.

    PubMed

    Luo, Pengju G; Wang, Haifang; Gu, Lingrong; Lu, Fushen; Lin, Yi; Christensen, Kenneth A; Yang, Sheng-Tao; Sun, Ya-Ping

    2009-12-22

    It was reported previously that monosaccharide-functionalized single-walled carbon nanotubes (SWNTs) could interact with Bacillus anthracis (Sterne) spores with the mediation of a divalent cation such as Ca(2+) to result in significant spore aggregation and reduction in colony forming units. In this work a more systematic investigation was performed on interactions of the SWNTs functionalized with individual mannose and galactose moieties and their various dendritic configurations with B. anthracis and B. subtilis spores in the presence and absence of a divalent cation. Significant differences and selectivity between the Bacillus spores and between different sugars and their configurations were observed. The relevant results are presented, and their mechanistic implications are discussed.

  9. Investigation of Aromatic/Aliphatic Polyimides as Dispersants for Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delozier, Donavon M.; Watson, Kent A.; Smith, Joseph G., Jr.; Clancy, Thomas C.; Connell, John W.

    2006-01-01

    Novel aromatic/aliphatic polyimides were prepared from 2,7-diamino-9,9'- dioctylfluorene (AFDA) and aromatic dianhydrides. Upon investigating the effectiveness of these polyimides for dispersing single wall carbon nanotubes (SWNTs) in solution, three were discovered to disperse SWNTs in N,N-dimethylacetamide (DMAc). Two of these polyimides, one from 3,3',4,4'-oxydiphthalic anhydride (ODPA) and one from symmetric 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), were used to prepare nanocomposites. Homogeneous polyimide/SWNT suspensions from both polymers were used in the preparation of films and fibers containing up to 1 wt% SWNTs. The samples were thermally treated to remove residual solvent and the films were characterized for SWNT dispersion by optical and high resolution scanning electron microscopy (HRSEM). Electrical and mechanical properties of the films were also determined. Electrospun fibers were examined by HRSEM to characterize SWNT alignment and orientation.

  10. Tuning the nonlinear response of (6,5)-enriched single-wall carbon nanotubes dispersions

    NASA Astrophysics Data System (ADS)

    Aréstegui, O. S.; Silva, E. C. O.; Baggio, A. L.; Gontijo, R. N.; Hickmann, J. M.; Fantini, C.; Alencar, M. A. R. C.; Fonseca, E. J. S.

    2017-04-01

    Ultrafast nonlinear optical properties of (6,5)-enriched single-wall carbon nanotubes (SWCNTs) dispersions are investigated using the thermally managed Z-scan technique. As the (6,5) SWCNTs presented a strong resonance in the range of 895-1048 nm, the nonlinear refractive index (n2) and the absorption coefficients (β) measurements were performed tuning the laser exactly around absorption peak of the (6,5) SWCNTs. It is observed that the nonlinear response is very sensitive to the wavelength and the spectral behavior of n2 is strongly correlated to the tubes one-photon absorption band, presenting also a peak when the laser photon energy is near the tube resonance energy. This result suggests that a suitable selection of nanotubes types may provide optimized nonlinear optical responses in distinct regions of the electromagnetic spectrum. Analysis of the figures of merit indicated that this material is promising for ultrafast nonlinear optical applications under near infrared excitation.

  11. High rate capacitive performance of single-walled carbon nanotube aerogels

    SciTech Connect

    Van Aken, Katherine L.; Pérez, Carlos R.; Oh, Youngseok; Beidaghi, Majid; Joo Jeong, Yeon; Islam, Mohammad F.; Gogotsi, Yury

    2015-05-30

    Single-walled carbon nanotube (SWCNT) aerogels produced by critical-point-drying of wet-gel precursors exhibit unique properties, such as high surface-area-to-volume and strength-to-weight ratios. They are free-standing, are binder-free, and can be scaled to thicknesses of more than 1 mm. In this paper, we examine the electric double layer capacitive behavior of these materials using a common room temperature ionic liquid electrolyte, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI). Electrochemical performance is assessed through galvanostatic cycling, cyclic voltammetry and impedance spectroscopy. Results indicate stable capacitive performance over 10,000 cycles as well as an impressive performance at high charge and discharge rates, due to accessible pore networks and enhanced electronic and ionic conductivities of SWCNT aerogels. Finally, these materials can find applications in mechanically compressible and flexible supercapacitor devices with high power requirements.

  12. High rate capacitive performance of single-walled carbon nanotube aerogels

    DOE PAGES

    Van Aken, Katherine L.; Pérez, Carlos R.; Oh, Youngseok; ...

    2015-05-30

    Single-walled carbon nanotube (SWCNT) aerogels produced by critical-point-drying of wet-gel precursors exhibit unique properties, such as high surface-area-to-volume and strength-to-weight ratios. They are free-standing, are binder-free, and can be scaled to thicknesses of more than 1 mm. In this paper, we examine the electric double layer capacitive behavior of these materials using a common room temperature ionic liquid electrolyte, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI). Electrochemical performance is assessed through galvanostatic cycling, cyclic voltammetry and impedance spectroscopy. Results indicate stable capacitive performance over 10,000 cycles as well as an impressive performance at high charge and discharge rates, due to accessible pore networks andmore » enhanced electronic and ionic conductivities of SWCNT aerogels. Finally, these materials can find applications in mechanically compressible and flexible supercapacitor devices with high power requirements.« less

  13. Non-radiative Exciton Decay in Single-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Harrah, Mark; Swan, Anna

    2010-03-01

    Experiments have shown step-wise changes in the fluorescence intensity from single-walled carbon nanotubes [1,2]. It has been proposed that the underlying mechanism for the step-wise changes is diffusion-limited quenching of excitons at defects [1]. This property has been used to demonstrate single-molecule detection for biological applications [3]. We perform a Monte-Carlo simulation of nanotube fluorescence with a diffusion-limited quenching model. The fluorescence intensity is seen to depend on the mean-square distance between defects, implying a nonlinear dependence on the number of defects. The intensity for consecutive defect counts can overlap depending on the positions of the defects. [4pt] [1] Cognet, L. et al. Science 316, 1465-1468 (2007).[0pt] [2] Jin, H. et al. Nano Lett. 8, 4299-4304 (2008).[0pt] [3] Heller, D. A. et al. Nature Nanotech. 4, 114-120 (2009).

  14. Tuning the driving force for exciton dissociation in single-walled carbon nanotube heterojunctions

    NASA Astrophysics Data System (ADS)

    Ihly, Rachelle; Mistry, Kevin S.; Ferguson, Andrew J.; Clikeman, Tyler T.; Larson, Bryon W.; Reid, Obadiah; Boltalina, Olga V.; Strauss, Steven H.; Rumbles, Garry; Blackburn, Jeffrey L.

    2016-06-01

    Understanding the kinetics and energetics of interfacial electron transfer in molecular systems is crucial for the development of a broad array of technologies, including photovoltaics, solar fuel systems and energy storage. The Marcus formulation for electron transfer relates the thermodynamic driving force and reorganization energy for charge transfer between a given donor/acceptor pair to the kinetics and yield of electron transfer. Here we investigated the influence of the thermodynamic driving force for photoinduced electron transfer (PET) between single-walled carbon nanotubes (SWCNTs) and fullerene derivatives by employing time-resolved microwave conductivity as a sensitive probe of interfacial exciton dissociation. For the first time, we observed the Marcus inverted region (in which driving force exceeds reorganization energy) and quantified the reorganization energy for PET for a model SWCNT/acceptor system. The small reorganization energies (about 130 meV, most of which probably arises from the fullerene acceptors) are beneficial in minimizing energy loss in photoconversion schemes.

  15. Coupling between flexural modes in free vibration of single-walled carbon nanotubes

    SciTech Connect

    Liu, Rumeng; Wang, Lifeng

    2015-12-15

    The nonlinear thermal vibration behavior of a single-walled carbon nanotube (SWCNT) is investigated by molecular dynamics simulation and a nonlinear, nonplanar beam model. Whirling motion with energy transfer between flexural motions is found in the free vibration of the SWCNT excited by the thermal motion of atoms where the geometric nonlinearity is significant. A nonlinear, nonplanar beam model considering the coupling in two vertical vibrational directions is presented to explain the whirling motion of the SWCNT. Energy in different vibrational modes is not equal even over a time scale of tens of nanoseconds, which is much larger than the period of fundamental natural vibration of the SWCNT at equilibrium state. The energy of different modes becomes equal when the time scale increases to the microsecond range.

  16. Plasma-Etching of Spray-Coated Single-Walled Carbon Nanotube Films for Biointerfaces

    NASA Astrophysics Data System (ADS)

    Kim, Joon Hyub; Lee, Jun-Yong; Min, Nam Ki

    2012-08-01

    We present an effective method for the batch fabrication of miniaturized single-walled carbon nanotube (SWCNT) film electrodes using oxygen plasma etching. We adopted the approach of spray-coating for good adhesion of the SWCNT film onto a pre-patterned Pt support and used O2 plasma patterning of the coated films to realize efficient biointerfaces between SWCNT surfaces and biomolecules. By these approaches, the SWCNT film can be easily integrated into miniaturized electrode systems. To demonstrate the effectiveness of plasma-etched SWCNT film electrodes as biointerfaces, Legionella antibody was selected as analysis model owing to its considerable importance to electrochemical biosensors and was detected using plasma-etched SWCNT film electrodes and a 3,3',5,5'-tetramethyl-benzidine dihydrochloride/horseradish peroxidase (TMB/HRP) catalytic system. The response currents increased with increasing concentration of Legionella antibody. This result indicates that antibodies were effectively immobilized on plasma-etched and activated SWCNT surfaces.

  17. Two layer 4:4 co-ordinated KI crystals grown within single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sloan, J.; Novotny, M. C.; Bailey, S. R.; Brown, G.; Xu, C.; Williams, V. C.; Friedrichs, S.; Flahaut, E.; Callender, R. L.; York, A. P. E.; Coleman, K. S.; Green, M. L. H.; Dunin-Borkowski, R. E.; Hutchison, J. L.

    2000-10-01

    The formation of `all surface' 4:4 co-ordinated KI crystals within 1.4 nm diameter single walled carbon nanotubes (SWNT) is reported. KI was inserted into the SWNTs by a capillary method [J. Sloan, D.M. Wright, H.G. Woo, S. Bailey, G. Brown, A.P.E. York, K.S. Coleman, J.L. Hutchison, M.L.H. Green, J. Chem. Soc. Chem. Commun. (1999) 699], whereby the nanotubes were combined intimately with the molten halide. The crystals grew with <0 0 1> (relative to bulk KI) parallel to the tubule axes and were continuous tetragonally distorted bilayer crystals composed of alternating columns of K-I and I-K pairs when viewed along <1 0 0> .

  18. Growing and characterizing one-dimensional crystals within single-walled carbon nanotubes.

    PubMed

    Hutchison, John L; Sloan, Jeremy; Kirkland, Angus I; Green, Malcolm L H

    2004-01-01

    Single-walled carbon nanotubes (SWNTs) have been used as growth templates for spatially confined crystal growth. The comparative crystallization and high-resolution transmission electron microscopy imaging properties of simple binary halides formed by the alkali iodides MI (M = Li, K, Na, Rb and Cs) within SWNTs are described. The most common structure type observed within SWNTs was the rocksalt archetype, although CsI was observed to form both body-centred cubic (bcc) and rocksalt structure types. ThCl4 was found to form a chain structure of Th[Cl]8 polyhedra. HgI2 crystallized within nanotubes with ultra-narrow (i.e. 0.8 nm) capillaries was observed to form helical 2 x 1 layer crystals.

  19. Solubilization of Single-Walled Carbon Nanotubes Using Ozone Generated by Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Khaled, Usama; Tomita, Hironari; Li, Zhenyu; Imasaka, Kiminobu; Suehiro, Junya

    2010-05-01

    This paper describes effects of ozone (O3) concentration on water-solubility of single-walled carbon nanotubes (SWCNTs). Ozone was generated by dielectric barrier discharge (DBD) in atmospheric air with the maximum concentration of 220 ppm. Water solubility of ozone-treated SWCNTs, which was evaluated by optical absorbance of the SWCNT suspension, increased with ozone treatment time and reached the maximum in 60 min. The dispersed SWCNTs suspension was stable even after two months of the ozone treatment. Fourier transform infrared (FTIR) spectroscopy and Raman spectra analysis revealed that SWCNTs surface was functionalized with chemical group such as -COO- after the ozone treatment. The longer ozone treatment introduced more functional groups and decreased zeta potential of the SWCNT surface, which improved water-solubility of the SWCNTs due to electrostatic repulsion force between them. It was also found that the ozone treatment induced morphological changes of SWCNTs.

  20. Activity inhibition on municipal activated sludge by single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Parise, Alex; Thakor, Harshrajsinh; Zhang, Xiaoqi

    2014-01-01

    The objective of this study was to evaluate the respiratory activity inhibition of activated sludge used in a typical wastewater treatment plant by single-walled carbon nanotubes (SWCNTs) with different length and functionality. Four types of SWCNTs were evaluated: short, functionalized short, long, and functionalized long. Based on the effective concentration (EC50) values obtained, we determined that functionalized SWCNTs resulted in a higher microbial respiratory inhibition than non-functionalized nanotubes, and long SWCNTs gave a higher microbial respiratory inhibition than their short counterparts. Among the four types of SWCNTs studied, functionalized long exhibited the highest respiration inhibition. Scanning electron microscopy imaging indicates that the long SWCNTs dispersed more favorably after sonication than the short variety. The findings demonstrated that the toxicity of CNTs (exhibited by respiratory inhibition) is related to their physical properties; the length and functionality of SWCNTs affected the toxicity of SWCNTs in a mixed-cultured biologic system.

  1. Cell response to single-walled carbon nanotubes in hybrid porous collagen sponges.

    PubMed

    Mao, Hongli; Kawazoe, Naoki; Chen, Guoping

    2015-02-01

    Three-dimensional (3D) porous collagen sponges incorporated with single-walled carbon nanotubes (SWCNTs) were prepared and used for 3D culture of bovine articular chondrocytes (BACs). The pore structures of the sponges were controlled by using ice particulates as a porogen material. The responses of cells to SWCNTs were investigated in this 3D cell culture system by evaluation of cell functions and cellular uptake of SWCNTs. The results showed that cells adhered and spatially distributed in the porous sponges. The incorporation of SWCNTs in the porous sponges promoted cell proliferation and production of sulfated glycosaminoglycans (sGAG). Confocal Raman imaging revealed that SWCNTs could be internalized by cells. The hybrid porous sponges not only provided nanostructured pore surfaces to facilitate cell proliferation and extracellular matrix (ECM) secretion but also supplied nanomaterials for cellular uptake which may be useful for biomedical applications.

  2. Single-molecule electrical biosensors based on single-walled carbon nanotubes.

    PubMed

    Guo, Xuefeng

    2013-07-05

    Interactions between biological molecules are fundamental to biology. Probing the complex behaviors of biological systems at the molecular level provides new opportunities to uncover the wealth of molecular information that is usually hidden in conventional ensemble experiments and address the "unanswerable" questions in the physical, chemical and biological sciences. Nanometer-scale materials are particularly well matched with biomolecular interactions due to their biocompatibility, size comparability, and remarkable electrical properties, thus setting the basis for biological sensing with ultrahigh sensitivity. This brief review aims to highlight the recent progress of the burgeoning field of single-molecule electrical biosensors based on nanomaterials, with a particular focus on single-walled carbon nanotubes (SWNTs), for better understanding of the molecular structure, interacting dynamics, and molecular functions. The perspectives and key issues that will be critical to the success of next-generation single-molecule biosensors toward practical applications are also discussed, such as the device reproducibility, system integration, and theoretical simulation.

  3. Single walled carbon nanotubes as drug delivery vehicles: targeting doxorubicin to tumors.

    PubMed

    Meng, Lingjie; Zhang, Xiaoke; Lu, Qinghua; Fei, Zhaofu; Dyson, Paul J

    2012-02-01

    Single walled carbon nanotubes (SWNTs) are emerging as promising delivery vehicles for cancer diagnostics and chemotherapies due to their unique properties, including, remarkable cell membrane penetrability, high drug-carrying capacities, pH-dependent therapeutic unloading, prolonged circulating times and intrinsic fluorescent, photothermal, photoacoustic and Raman properties. In this leading opinion paper, we systemically discuss and evaluate the relationship of the biological safety of SWNTs with their physicochemical properties such as their length, purity, agglomeration state, concentration and surface functionalization. Other relevant issues, including the cellular uptake mechanism, biodistribution and metabolism of SWNTs are also reviewed. The design and preparation of SWNT-based drug delivery systems (DDSs) and their pharmacokinetic, cancer targeting and therapeutic properties both in vitro and in vivo are highlighted. Future opportunities and challenges of SWNT-based DDSs are also discussed.

  4. Laser images recording on aerosol-synthesized single-walled carbon nanotube films

    NASA Astrophysics Data System (ADS)

    Mikheev, G. M.; Mikheev, K. G.; Anoshkin, I. V.; Nasibulin, A. G.

    2015-09-01

    It is shown that images on semitransparent conducting films of aerosol-synthesized single-walled carbon nanotubes (SWCNTs) can be recorded using focused low-power radiation of a He-Ne laser operating at a wavelength of 632.8 nm. Both free-standing films and those deposited on glass or polymer substrates can be used. Laser recording of images on the polymer-supported films is possible due to their transparency increased as a result of chemical reactions between iron nanoparticles encapsulated in SWCNTs and the products of local thermal decomposition of the polymer. Recording on the free-standing SWCNT films and those supported on glass substrates was performed upon acid treatment of the film surface.

  5. Self-assembly of linear arrays of semiconductor nanoparticles on carbon single-walled nanotubes.

    PubMed

    Engtrakul, Chaiwat; Kim, Yong-Hyun; Nedeljković, Jovan M; Ahrenkiel, S Phil; Gilbert, Katherine E H; Alleman, Jeff L; Zhang, S B; Mićić, Olga I; Nozik, Arthur J; Heben, Michael J

    2006-12-21

    Ligand-stabilized nanocrystals (NCs) were strongly bound to the nanotube surfaces by simple van der Waals forces. Linear arrays of CdSe and InP quantum dots were formed by self-assembly using the grooves in bundles of carbon single-walled nanotubes (SWNTs) as a one-dimensional template. A simple geometrical model explains the ordering in terms of the anisotropic properties of the nanotube surface. CdSe quantum rods were also observed to self-organize onto SWNTs with their long axis parallel to the nanotube axis. This approach offers a route to the formation of ordered NC/SWNT architectures that avoids problems associated with surface derivatization.

  6. Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

    NASA Astrophysics Data System (ADS)

    Jilili, Jiwuer; Abdurahman, Ayjamal; Gülseren, Oǧuz; Schwingenschlögl, Udo

    2014-07-01

    We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

  7. Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

    NASA Astrophysics Data System (ADS)

    Jiwuer, Jilili; Abdurahman, Ayjamal; Gülseren, Oğuz; Schwingenschlögl, Udo

    2015-03-01

    We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation (GGA) a non-binding state, whereas the local density approximation (LDA) predicts reasonable binding energies. The results coincide after inclusion of van der Waals (vdW) corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization. Research reported in this publication was supported by the King Abdullah University of Science and Technology (KAUST).

  8. Rings of single-walled carbon nanotubes: molecular-template directed assembly and Monte Carlo modeling.

    PubMed

    Zou, Shengli; Maspoch, Daniel; Wang, Yuhuang; Mirkin, Chad A; Schatz, George C

    2007-02-01

    Rings of single-walled carbon nanotubes (SWNTs) were assembled by dip-pen nanolithography (DPN) generated molecular templates consisting of COOH-terminated monolayers in circular patterns surrounded by passivating CH3-terminated SAMs. Experimental data and atomic-level Monte Carlo simulations show that SWNTs assemble into rings with radii as small as 100 nm at the edge of the COOH templates. This directed assembly is strongly length-dependent; only when the length of a SWNT is longer than half of the circumference of the circle does the SWNT bend to precisely follow the interface of the COOH-terminated monolayer. The theoretical modeling shows that the strain energy of each SWNT is balanced by the energy difference between the van der Waals interactions of the tube with COOH and CH3 templates to produce the resulting ring structure.

  9. Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

    PubMed Central

    García-García, Amanda; Vergaz, Ricardo; Algorri, José F; Zito, Gianluigi; Cacace, Teresa; Marino, Antigone; Otón, José M

    2016-01-01

    Summary Single-wall carbon nanotubes (SWCNT) are anisotropic nanoparticles that can cause modifications in the electrical and electro-optical properties of liquid crystals. The control of the SWCNT concentration, distribution and reorientation in such self-organized fluids allows for the possibility of tuning the liquid crystal properties. The alignment and reorientation of CNTs are studied in a system where the liquid crystal orientation effect has been isolated. Complementary studies including Raman spectroscopy, microscopic inspection and impedance studies were carried out. The results reveal an ordered reorientation of the CNTs induced by an electric field, which does not alter the orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules. PMID:27547599

  10. Crystalline transformations in nylon-6/single-walled carbon nanotube nanocomposites.

    PubMed

    Naffakh, M; Marco, C; Gómez, M A; Ellis, G; Maser, W K; Benito, A; Martínez, M T

    2009-10-01

    Nylon-6/single-walled carbon nanotube (SWNT) nanocomposites with different SWNTs loadings were prepared by melt-blending. An efficient dispersion of SWNTs into the nylon-6 matrix was confirmed by scanning electron microscopy. DSC and time-resolved synchrotron X-ray diffraction were used to provide detailed information on the effect of SWNTs on the crystalline phase transition of nylon-6 in the nanocomposites. The incorporation of SWNTs accelerated the crystallization rate of nylon-6 due to a nucleating effect. The variable-temperature WAXS experiments, in both neat nylon-6 and nylon-6 nanocomposites, showed that the crystallization from the melt occured through the formation of the pseudo-hexagonal crystal form (gamma) and its transformation to the monoclinic form (alpha) on cooling. Additionally, this crystalline transition was reversible as observed upon heating. The alpha-gamma crystalline transformation temperature of nylon-6 was dependent on heating rate and, more importantly, on the SWNT content.

  11. Dendron growth from vertically aligned single-walled carbon nanotube thin layer arrays for photovoltaic devices.

    PubMed

    Bissett, Mark Alexander; Köper, Ingo; Quinton, Jamie Scott; Shapter, Joe George

    2011-04-07

    Single-walled carbon nanotube arrays attached to conductive transparent electrodes have previously shown promise for use in photovoltaic devices, whilst still retaining light transmission. Here, chemical modification of these thin (<200 nm) arrays with PAMAM-type dendrons has been undertaken to enhance the photoresponse of these devices. The effect of modification on the electrode was measured by differential pulse voltammetry to detect the dendrons, and the effect on the nanotubes was measured by Raman spectroscopy. Solar simulator illumination of the cells was performed to measure the effect of the nanotube modification on the cell power, and determine the optimal modification. Electrochemical impedance spectroscopy was also used to investigate the equivalent electronic circuit elements of the cells. The optimal dendron modification occurred with the second generation (G-2.0), which gave a 70% increase in power over the unmodified nanotube array.

  12. Tuning the driving force for exciton dissociation in single-walled carbon nanotube heterojunctions

    SciTech Connect

    Ihly, Rachelle; Mistry, Kevin S.; Ferguson, Andrew J.; Clikeman, Tyler T.; Larson, Bryon W.; Reid, Obadiah; Boltalina, Olga V.; Strauss, Steven H.; Rumbles, Garry; Blackburn, Jeffrey L.

    2016-04-25

    Understanding the kinetics and energetics of interfacial electron transfer in molecular systems is crucial for the development of a broad array of technologies, including photovoltaics, solar fuel systems and energy storage. The Marcus formulation for electron transfer relates the thermodynamic driving force and reorganization energy for charge transfer between a given donor/acceptor pair to the kinetics and yield of electron transfer. Here we investigated the influence of the thermodynamic driving force for photoinduced electron transfer (PET) between single-walled carbon nanotubes (SWCNTs) and fullerene derivatives by employing time-resolved microwave conductivity as a sensitive probe of interfacial exciton dissociation. For the first time, we observed the Marcus inverted region (in which driving force exceeds reorganization energy) and quantified the reorganization energy for PET for a model SWCNT/acceptor system. The small reorganization energies (about 130 meV, most of which probably arises from the fullerene acceptors) are beneficial in minimizing energy loss in photoconversion schemes.

  13. The effect of catalyst concentration on the synthesis of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Yufang; Zhang, Zhensheng; Liu, Haoran; Xu, Xiaoxuan; Pan, Guiling; Guo, Zunhuai; Liu, Youying; Han, Xuanyou; Lan, Guoxiang

    2002-08-01

    Single wall carbon nanotubes (SWNTs) were synthesized by electric arc discharge method with a mixture of nickel and yttrium as catalysts. The effect of the catalyst concentration on the synthesis of SWNTs was studied. Raman spectra of SWNTs have been recorded with excitation wavelengths from 476.5 to 1064 nm. The Raman peaks of the radial breathing modes (RBM) of SWNTs were assigned. The results indicate that the diameter distribution of SWNTs is in the range of 1.2-1.6 nm, and the SWNTs with diameter 1.43 nm are in the majority. The catalyst concentrations have large effect on the yield of SWNTs and little effect on the diameter distribution of SWNTs.

  14. Electron diffraction and microscopy of single-wall carbon nanotube bundles produced by different methods

    NASA Astrophysics Data System (ADS)

    Colomer, J.-F.; Henrard, L.; Lambin, Ph.; van Tendeloo, G.

    2002-05-01

    The atomic structure of single-wall carbon nanotube bundles produced by three different techniques (laser ablation, electric arc discharge and catalytic chemical vapor deposition (CCVD)) has been characterized by electron diffraction and microscopy. Information on the helicity and the lattice packing has been obtained. Concerning the helicity, small bundles produced by CCVD exhibit only one or two tube helicities within a single bundle. The diffraction patterns of laser-ablation produced bundles also present well-defined but more diversified chiralities within a single bundle. By contrast the data acquired on bundles formed by arc discharge show a more diffuse pattern, characteristic of a random chirality dispersion within a single bundle. Concerning the lattice packing, informations are obtained via a detailed study of the equatorial line of the diffraction pattern for bundles produced by the three techniques. This electron diffraction study is completed by high-resolution electron microscopy.

  15. The effect of catalyst concentration on the synthesis of single-wall carbon nanotubes.

    PubMed

    Wang, Yufang; Zhang, Zhensheng; Liu, Haoran; Xu, Xiaoxuan; Pan, Guiling; Guo, Zunhuai; Liu, Youying; Han, Xuanyou; Lan, Guoxiang

    2002-08-01

    Single wall carbon nanotubes (SWNTs) were synthesized by electric arc discharge method with a mixture of nickel and yttrium as catalysts. The effect of the catalyst concentration on the synthesis of SWNTs was studied. Raman spectra of SWNTs have been recorded with excitation wavelengths from 476.5 to 1064 nm. The Raman peaks of the radial breathing modes (RBM) of SWNTs were assigned. The results indicate that the diameter distribution of SWNTs is in the range of 1.2-1.6 nm, and the SWNTs with diameter 1.43 nm are in the majority. The catalyst concentrations have large effect on the yield of SWNTs and little effect on the diameter distribution of SWNTs.

  16. Optical and thermal response of single-walled carbon nanotube-copper sulfide nanoparticle hybrid nanomaterials.

    PubMed

    Tseng, Yi-Hsuan; He, Yuan; Lakshmanan, Santana; Yang, Chang; Chen, Wei; Que, Long

    2012-11-16

    This paper reports the optical and thermal response of a single-walled carbon nanotube-copper sulfide nanoparticle (SWNT-CuS NP) hybrid nanomaterial and its application as a thermoelectric generator. The hybrid nanomaterial was synthesized using oleylamine molecules as the linker molecules between SWNTs and CuS NPs. Measurements found that the hybrid nanomaterial has significantly increased light absorption (up to 80%) compared to the pure SWNT. Measurements also found that the hybrid nanomaterial thin-film devices exhibit a clear optical and thermal switching effect, which can be further enhanced up to 10 ×  by asymmetric illumination of light and thermal radiation on the thin-film devices instead of symmetric illumination. A simple prototype thermoelectric generator enabled by the hybrid nanomaterials is demonstrated, indicating a new route for achieving thermoelectricity.

  17. Charge trapping in aligned single-walled carbon nanotube arrays induced by ionizing radiation exposure

    SciTech Connect

    Esqueda, Ivan S.; Cress, Cory D.; Che, Yuchi; Cao, Yu; Zhou, Chongwu

    2014-02-07

    The effects of near-interfacial trapping induced by ionizing radiation exposure of aligned single-walled carbon nanotube (SWCNT) arrays are investigated via measurements of gate hysteresis in the transfer characteristics of aligned SWCNT field-effect transistors. Gate hysteresis is attributed to charge injection (i.e., trapping) from the SWCNTs into radiation-induced traps in regions near the SWCNT/dielectric interface. Self-consistent calculations of surface-potential, carrier density, and trapped charge are used to describe hysteresis as a function of ionizing radiation exposure. Hysteresis width (h) and its dependence on gate sweep range are investigated analytically. The effects of non-uniform trap energy distributions on the relationship between hysteresis, gate sweep range, and total ionizing dose are demonstrated with simulations and verified experimentally.

  18. Diameter Dependence of Lattice Thermal Conductivity of Single-Walled Carbon Nanotubes: Study from Ab Initio.

    PubMed

    Yue, Sheng-Ying; Ouyang, Tao; Hu, Ming

    2015-10-22

    The effects of temperature, tube length, defects, and surface functionalization on the thermal conductivity (κ) of single-walled carbon nanotubes (SWCNTs) were well documented in literature. However, diameter dependence of thermal conductivity of SWCNTs received less attentions. So far, diverse trends of the diameter dependence have been discussed by different methods and all the previous results were based on empirical interatomic potentials. In this paper, we emphasize to clarify accurate κ values of SWCNTs with different diameters and in-plane κ of graphene. All the studies were under the framework of anharmonic lattice dynamics and Boltzmann transport equation (BTE) based on first principle calculations. We try to infer the right trend of diameter dependent thermal conductivity of SWCNTs. We infer that graphene is the limitation as SWCNT with an infinite diameter. We analyzed the thermal conductivity contributions from each phonon mode in SWCNTs to explain the trend. Meanwhile, we also identify the extremely low thermal conductivity of ultra-thin SWCNTs.

  19. Raman studies of solutions of single-wall carbon nanotube salts.

    PubMed

    Anglaret, E; Dragin, F; Pénicaud, A; Martel, R

    2006-03-09

    Polyelectrolyte solutions of Na-doped single-wall carbon nanotube (SWNT) salts are studied by Raman spectroscopy. Their Raman signature is first compared to undoped SWNT suspensions and dry alkali-doped SWNT powders, and the results indicate that the nanotube solutions consist of heavily doped (charged) SWNT. Raman signature of doping is then used to monitor in situ the oxidation reaction of the nanotube salt solutions upon exposure to air and to an acceptor molecule (benzoquinone). The results indicate a direct charge-transfer reaction from the acceptor molecule to the SWNT, leading to their gradual charge neutralization and eventual precipitation in solution. The results are consistent with a simple redox titration process occurring at the thermodynamical equilibrium.

  20. A new designed π conjugated molecule for stable single walled carbon nanotube dispersion in aqueous medium.

    PubMed

    Nogueira, S L; Sahoo, S K; Jarrosson, T; Serein-Spirau, F; Lère-Porte, J-P; Moujaes, E A; Marletta, A; Santos, A P; Fantini, C; Furtado, C A; Silva, R A

    2016-02-15

    A molecule with a π conjugated backbone built from aromatic thiophene and dialkoxyphenylene units and substituted imidazolium groups (TPO) is designed to obtain ultra-stable single walled carbon nanotube (SWCNT) dispersion in aqueous medium. The proposed mechanism of non-covalent interaction is accompanied by individualization of SWCNT and comprises of dominant nondisruptive π-π and cation-π interaction between them and the TPO conjugated oligomer. The individualization of SWCNT and dispersibility and stability of the ultra-stable suspensions were estimated using high resolution transmission electron microscopy, UV-Visible-NIR absorption spectroscopy, Raman spectroscopy, photoluminescence and zeta potential measurement. Nuclear magnetic resonance data provides direct evidence toward possible cation-π interaction.