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Sample records for 2-aminophenoxazin-3-one-functionalized multiwalled carbon

  1. Multiwall carbon nanotube microcavity arrays

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm2) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170-180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  2. Electrical properties of multiwalled carbon nanotube film

    SciTech Connect

    Antonenko, S. V. Malinovskaya, O. S.; Mal'tsev, S. N.

    2007-07-15

    The multiwalled carbon nanotube films examined in this study are produced by two methods: current annealing of carbon paper and dc magnetron sputtering. The conductivity and the temperature dependence of resistance of the samples are measured. The thermal conductivity of the film-substrate system is evaluated.

  3. Ultralight multiwalled carbon nanotube aerogel.

    PubMed

    Zou, Jianhua; Liu, Jianhua; Karakoti, Ajay Singh; Kumar, Amit; Joung, Daeha; Li, Qiang; Khondaker, Saiful I; Seal, Sudipta; Zhai, Lei

    2010-12-28

    Ultralight multiwalled carbon nanotube (MWCNT) aerogel is fabricated from a wet gel of well-dispersed pristine MWCNTs. On the basis of a theoretical prediction that increasing interaction potential between CNTs lowers their critical concentration to form an infinite percolation network, poly(3-(trimethoxysilyl) propyl methacrylate) (PTMSPMA) is used to disperse and functionalize MWCNTs where the subsequent hydrolysis and condensation of PTMSPMA introduces strong and permanent chemical bonding between MWCNTs. The interaction is both experimentally and theoretically proven to facilitate the formation of a MWCNT percolation network, which leads to the gelation of MWCNT dispersion at ultralow MWCNT concentration. After removing the liquid component from the MWCNT wet gel, the lightest ever free-standing MWCNT aerogel monolith with a density of 4 mg/cm(3) is obtained. The MWCNT aerogel has an ordered macroporous honeycomb structure with straight and parallel voids in 50-150 μm separated by less than 100 nm thick walls. The entangled MWCNTs generate mesoporous structures on the honeycomb walls, creating aerogels with a surface area of 580 m(2)/g which is much higher than that of pristine MWCNTs (241 m(2)/g). Despite the ultralow density, the MWCNT aerogels have an excellent compression recoverable property as demonstrated by the compression test. The aerogels have an electrical conductivity of 3.2 × 10(-2) S·cm(-1) that can be further increased to 0.67 S·cm(-1) by a high-current pulse method without degrading their structures. The excellent compression recoverable property, hierarchically porous structure with large surface area, and high conductivity grant the MWCNT aerogels exceptional pressure and chemical vapor sensing capabilities. PMID:21090673

  4. Carbon linear chains inside multiwalled nanotubes

    NASA Astrophysics Data System (ADS)

    Cazzanelli, E.; Caputi, L.; Castriota, M.; Cupolillo, A.; Giallombardo, C.; Papagno, L.

    2007-09-01

    Multiwalled carbon nanotubes have been deposited on graphite cathodes by using an arc discharge technique in He atmosphere, with the insertion of a catalytic Ni-Cr mixture as well as without catalysers. The topography of such deposition has been investigated by SEM, while a parallel micro-Raman study has revealed, in particular regions of the deposited cathodes, strong bands in the range 1780-1860 cm -1, assignable to linear carbon chains inside the nanotubes. The variation of intensity, frequency and bandwidth of such bands has been investigated, in relation with the spectral characters of the host multiwalled carbon nanotube. In the cathode deposited without catalyst a quite ordered configuration of multiwalled carbon nanotubes is obtained in the central zone, while the maximum concentration of linear carbon chains is found in a ring shaped zone just inside the border. In sample obtained with catalyst the deposited multiwalled carbon nanotubes appear always more disordered, and a remarkable concentration of carbon chains appears in some zones, with a more casual distribution.

  5. Multiwalled Carbon nanotube - Strength to polymer composite

    NASA Astrophysics Data System (ADS)

    Pravin, Jagdale; Khan, Aamer. A.; Massimo, Rovere; Carlo, Rosso; Alberto, Tagliaferro

    2016-02-01

    Carbon nanotubes (CNTs), a rather fascinating material, are among the pillars of nanotechnology. CNTs exhibit unique electrical, mechanical, adsorption, and thermal properties with high aspect ratio, exceptional stiffness, excellent strength, and low density, which can be exploited in the manufacturing of revolutionary smart nano composite materials. The demand for lighter and stronger polymer composite material in various applications is increasing every day. Among all the possibilities to research and exploit the exceptional properties of CNTs in polymer composites we focused on the reinforcement of epoxy resin with different types of multiwalled carbon nano tubes (MWCNTs). We studied mechanical properties such as stress, strain, ultimate tensile strength, yield point, modulus and fracture toughness, and Young's modulus by plotting and calculating by means of the off-set method. The mechanical strength of epoxy composite is increased intensely with 1 and 3 wt.% of filler.

  6. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    EPA Science Inventory

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Der...

  7. A thermodynamic model for growth mechanisms of multiwall carbon nanotubes.

    SciTech Connect

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

    2006-02-01

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

  8. Multiwalled carbon nanotube film for strain sensing

    NASA Astrophysics Data System (ADS)

    Li, X.; Levy, C.; Elaadil, L.

    2008-01-01

    We have studied the possibility of using multiwalled carbon nanotube (MWCNT) films as strain sensors. The MWCNT films were prepared by a solution/filtration method and were bonded directly onto specimens by a nonconductive adhesive. For comparison, conventional foil strain gages were also bonded to the structure on the opposite side. The specimens then underwent a uniaxial tensile load-unload cycle to evaluate them as strain sensors. To ensure good electrical contact between carbon nanotube film and the wires, a thin layer of copper was thermally deposited on both ends of the film as electrodes, and the wires were connected to the electrodes by silver ink. Wheatstone bridges were used to convert the resistance changes of the MWCNTs to voltage output. Results indicated that the output voltages were proportional to the strain readings from the stain indicator. The effect of temperature on the resistance was measured and the MWCNT film resistance was found to be independent of temperature over the range 273-363 K. The optimal film dimension for strain sensing was evaluated as well. Dynamic tests suggest that the MWCNTs were able to extract the structural signature. Our results indicate that MWCNT film is potentially useful for structural health monitoring and vibration control applications.

  9. Multi-Walled Carbon Nanotube Growth in Multi-Walled Carbon Nanotubes by Chemical Vapor Deposition.

    PubMed

    Hasegawa, Takayuki; Arenas, Daniel J; Kohno, Hideo

    2015-02-01

    We report chemical vapor deposition (CVD) growth of a multi-walled carbon nanotube (MWCNT) inside another MWCNTs from a cementite (Fe3C) catalyst nanoparticles. The CNTs have bi or tri-layered core(s)-sheath structure with various crystallinity. The sheath grows first at a lower temperature, and then the catalyst nanoparticle works again to grow the core(s) at a higher temperature in the tip or root growth mode. Transmission electron microscopy (TEM) observation provides a clear piece of evidence of reverse-inward growth. PMID:26353735

  10. 40 CFR 721.10155 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for...

  11. 40 CFR 721.10663 - Functionalized multi-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 Functionalized multi-walled carbon... Specific Chemical Substances § 721.10663 Functionalized multi-walled carbon nanotubes (generic). (a... generically as functionalized multi-walled carbon nanotubes (PMN P-12-44) is subject to reporting under...

  12. 40 CFR 721.10663 - Functionalized multi-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 Functionalized multi-walled carbon... Specific Chemical Substances § 721.10663 Functionalized multi-walled carbon nanotubes (generic). (a... generically as functionalized multi-walled carbon nanotubes (PMN P-12-44) is subject to reporting under...

  13. 40 CFR 721.10183 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for...

  14. 40 CFR 721.10155 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for...

  15. 40 CFR 721.10155 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for...

  16. 40 CFR 721.10183 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for...

  17. 40 CFR 721.10183 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for...

  18. 40 CFR 721.10671 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10671 Multi-walled carbon nanotubes (generic). (a) Chemical substances... multi-walled carbon nanotubes (PMNs P-09-198 and P-09-199) are subject to reporting under this...

  19. 40 CFR 721.10155 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for...

  20. 40 CFR 721.10183 - Multi-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 Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for...

  1. Ag-catalysed cutting of multi-walled carbon nanotubes.

    PubMed

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

    2016-04-29

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes. PMID:26987452

  2. Ag-catalysed cutting of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. Unzipped multiwalled carbon nanotube oxide/multiwalled carbon nanotube hybrids for polymer reinforcement.

    PubMed

    Fan, Jinchen; Shi, Zixing; Tian, Ming; Wang, Jialiang; Yin, Jie

    2012-11-01

    Multiwalled carbon nanotubes (MWNTs) have been widely used as nanofillers for polymer reinforcement. However, it has been restricted by the limited available interface area of MWNTs in the polymer matrices. Oxidation unzipping of MWNTs is an effective way to solve this problem. The unzipped multiwalled carbon nanotube oxides (UMCNOs) exhibit excellent enhancement effect with low weight fractions, but agglomeration of UMCNOs at a relatively higher loading still hampered the mechanical reinforcement of polymer composites. In this paper, we interestingly found that the dispersion of UMCNOs in polymer matrices can be significantly improved with the combination of pristine MWNTs. The hybrids of MWNTs and UMCNOs (U/Ms) can be easily obtained by adding the pristine MWNTs into the UMCNOs aqueous dispersion, followed by sonication. With a π-stacking interaction, the UMCNOs were attached onto the outwalls of MWNTs. The morphologies and structure of the U/Ms were characterized by several measurements. The mechanical testing of the resultant poly(vinyl alcohol) (PVA)-based composites demonstrated that the U/Ms can be used as ideal reinforcing fillers. Compared to PVA, the yield strength and Young's modulus of U/M-PVA composites with a loading of 0.7 wt % of the U/Ms approached ∼145.8 MPa and 6.9 GPa, respectively, which are increases of ∼107.4% and ∼122.5%, respectively. The results of tensile tests demonstrated that the reinforcement effect of U/Ms is superior to the individual UMCNOs and MWNTs, because of the synergistic interaction of UMCNOs and MWNTs. PMID:23121120

  4. Inhibition of Cancer Cell Migration by Multiwalled Carbon Nanotubes.

    PubMed

    García-Hevia, Lorena; Valiente, Rafael; Fernández-Luna, José L; Flahaut, Emmanuel; Rodríguez-Fernández, Lidia; Villegas, Juan C; González, Jesús; Fanarraga, Mónica L

    2015-08-01

    Inhibiting cancer cell migration and infiltration to other tissues makes the difference between life and death. Multiwalled carbon nanotubes (MWCNTs) display intrinsic biomimetic properties with microtubules, severely interfering with the function of these protein filaments during cell proliferation, triggering cell death. Here it is shown MWCNTs disrupt the centrosomal microtubule cytoskeletal organization triggering potent antimigratory effects in different cancer cells. PMID:26097131

  5. Buckling Test under Axial Compression for Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Nishio, Mitsumasa; Akita, Seiji; Nakayama, Yoshikazu

    2005-08-01

    We have investigated buckling phenomena under axial compression for multiwall carbon nanotubes with the same outer diameter with different wall thicknesses obtained by the extraction of inner shells. According to the Euler’s buckling model described by the continuum model, Young’s moduli of the nanotube before and after the extraction of the inner shells were evaluated to be 0.77 and 0.80 TPa, respectively. This good agreement between the two values indicates that the classical continuum model is effective for describing the mechanical behaviors of multiwall nanotubes.

  6. Preparation of supported electrocatalyst comprising multiwalled carbon nanotubes

    SciTech Connect

    Wu, Gang; Zelenay, Piotr

    2013-08-27

    A process for preparing a durable non-precious metal oxygen reduction electrocatalyst involves heat treatment of a ball-milled mixture of polyaniline and multiwalled carbon nanotubes in the presence of a Fe species. The catalyst is more durable than catalysts that use carbon black supports. Performance degradation was minimal or absent after 500 hours of operation at constant cell voltage of 0.40 V.

  7. Structural and surface features of multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hembram, K. P. S. S.; Rao, G. Mohan

    2011-04-01

    We present the direct evidence of defective and disorder places on the surface of multiwall carbon nanotube (MWCNT), visualizing the presence of amorphous carbon at those sites. These defective surfaces being higher in energy are the key features of functionalization with different materials. The interaction of the π orbital electrons of different carbon atoms of adjacent layers is more at the bent portion, than that of regular portion of the CNT. Hence the tubular structure of the bent portion of nanotubes is spaced more than that of regular portion of the nanotubes, minimizing the stress.

  8. Tensile Yielding of Multi-Wall Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Wei, Chenyu; Cho, Kyeongjae; Srivastava, Deepak; Parks, John W. (Technical Monitor)

    2002-01-01

    The tensile yielding of multiwall carbon nanotubes (MWCNTs) has been studied using Molecular Dynamics simulations and a Transition State Theory based model. We find a strong dependence of the yielding on the strain rate. A critical strain rate has been predicted above/below which yielding strain of a MWCNT is larger/smaller than that of the corresponding single-wall carbon nanotubes. At experimentally feasible strain rate of 1% /hour and T = 300K, the yield strain of a MWCNT is estimated to be about 3-4 % higher than that of an equivalent SWCNT (Single Wall Carbon Nanotube), in good agreement with recent experimental observations.

  9. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals. PMID:17980962

  10. Determination of the intershell conductance in a multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Stetter, A.; Vancea, J.; Back, C. H.

    2008-10-01

    We have measured the current induced voltage drop along an individual multiwall carbon nanotube as a function of the distance to the current injecting electrode. The measurements have been performed at room temperature using scanning probe potentiometry combined with scanning electron microscopy. For a nanotube with an incomplete outer shell, a sharp potential jump was observed at the end of the outermost shell. The electric potential variation along the carbon nanotube has been used to determine the contact resistance between metal electrodes and the tube, the intrashell resistance, and the intershell conductance.

  11. Quantum conductance steps in solutions of multiwalled carbon nanotubes.

    PubMed

    Urbina, A; Echeverría, I; Pérez-Garrido, A; Díaz-Sánchez, A; Abellán, J

    2003-03-14

    We have prepared solutions of multiwalled carbon nanotubes in Aroclor 1254, a mixture of polychlorinated biphenyls. The solutions are stable at room temperature. Transport measurements were performed using a scanning-tunneling probe on a sample prepared by spin coating the solution on gold substrates. Conductance steps were clearly seen. A histogram of a high number of traces shows maximum peaks at integer values of the conductance quantum G(0)=2e(2)/h, demonstrating ballistic transport at room temperature along the carbon nanotube over distances longer than 1.4 microm. PMID:12689021

  12. Electrocatalytic oxygen evolution at surface-oxidized multiwall carbon nanotubes.

    PubMed

    Lu, Xunyu; Yim, Wai-Leung; Suryanto, Bryan H R; Zhao, Chuan

    2015-03-01

    Large-scale storage of renewable energy in the form of hydrogen (H2) fuel via electrolytic water splitting requires the development of water oxidation catalysts that are efficient and abundant. Carbon-based nanomaterials such as carbon nanotubes have attracted significant applications for use as substrates for anchoring metal-based nanoparticles. We show that, upon mild surface oxidation, hydrothermal annealing and electrochemical activation, multiwall carbon nanotubes (MWCNTs) themselves are effective water oxidation catalysts, which can initiate the oxygen evolution reaction (OER) at overpotentials of 0.3 V in alkaline media. Oxygen-containing functional groups such as ketonic C═O generated on the outer wall of MWCNTs are found to play crucial roles in catalyzing OER by altering the electronic structures of the adjacent carbon atoms and facilitates the adsorption of OER intermediates. The well-preserved microscopic structures and highly conductive inner walls of MWCNTs enable efficient transport of the electrons generated during OER. PMID:25658670

  13. 40 CFR 721.10274 - Multi-walled carbon nanotubes (generic) (P-09-188).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... to undergo further processing except for mechanical processing. (2) The significant new uses are: (i... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10274 Multi-walled carbon nanotubes (generic) (P-09-188). (a)...

  14. 40 CFR 721.10275 - Multi-walled carbon nanotubes (generic) (P-09-0417).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... that is not intended to undergo further processing, except for mechanical processing. (2) The... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10275 Multi-walled carbon nanotubes (generic) (P-09-0417). (a)...

  15. 40 CFR 721.10703 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... into an article as defined at 40 CFR 721.3(c). (2) The significant new uses are: (i) Protection in the... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10703 Multi-walled carbon nanotubes (generic). (a) Chemical...

  16. Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes

    SciTech Connect

    Lan, Chun; Amama, Placidus B.; Fisher, Timothy S.; Reifenberger, Ronald G.

    2007-08-27

    A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950 deg. C. The lowest resistances were obtained mainly from MWNTs grown at 900 deg. C. The MWNT resistance is larger on average at lower (800 deg. C) and higher (950 deg. C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.

  17. Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lan, Chun; Amama, Placidus B.; Fisher, Timothy S.; Reifenberger, Ronald G.

    2007-08-01

    A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950°C. The lowest resistances were obtained mainly from MWNTs grown at 900°C. The MWNT resistance is larger on average at lower (800°C) and higher (950°C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.

  18. Macrodispersion of multi-walled carbon nanotubes for conductive films.

    PubMed

    Kim, Duckjong; Zhu, Lijing; Kim, Jae-Hyun; Han, Chang-Soo; Baik, Seunghyun

    2012-04-01

    Understanding of the effect of the multi-walled carbon nanotube (MWCNT) dispersion process on physical properties of MWCNT film is crucial in process optimization of MWCNT film-based products. In the present work, the electrical conduction property of MWCNT films according to various conditions in MWCNT dispersion is investigated. Spectroscopic analysis of dispersed MWCNTs show that the electrical resistance of the MWCNT conductive film is affected by an increase in the electrical contacts between adjacent CNTs due to CNT debundling and physical damage caused by ultrasonic processing. Based on the two conflicting parameters, dispersion guidelines for highly conductive MWCNT film are presented. PMID:22849134

  19. Reversible thermal switching of aqueous dispersibility of multiwalled carbon nanotubes.

    PubMed

    O'Driscoll, Luke J; Welsh, Daniel J; Bailey, Steven W D; Visontai, David; Frampton, Harry; Bryce, Martin R; Lambert, Colin J

    2015-03-01

    Easily reversible aqueous dispersion/precipitation of multiwalled carbon nanotubes (MWNTs) has been demonstrated using small-molecule non-ionic pyrene-based surfactants, which exhibit lower critical solution temperature (LCST) phase behaviour. The MWNTs are dispersed by means of non-covalent interactions. The dispersibility can be switched "off" (i.e., MWNTs precipitated) upon heating and switched "on" (i.e., MWNTs re-dispersed) upon cooling and merely swirling the sample at room temperature, that is, under very mild conditions. This effect is also observed under high ionic strength conditions with NaCl in the aqueous phase. PMID:25639258

  20. Multiwalled carbon nanotube reinforced biomimetic bundled gel fibres.

    PubMed

    Kim, Young-Jin; Yamamoto, Seiichiro; Takahashi, Haruko; Sasaki, Naruo; Matsunaga, Yukiko T

    2016-08-19

    This work describes the fabrication and characterization of hydroxypropyl cellulose (HPC)-based biomimetic bundled gel fibres. The bundled gel fibres were reinforced with multiwalled carbon nanotubes (MWCNTs). A phase-separated aqueous solution with MWCNT and HPC was transformed into a bundled fibrous structure after being injected into a co-flow microfluidic device and applying the sheath flow. The resulting MWCNT-bundled gel fibres consist of multiple parallel microfibres. The mechanical and electrical properties of MWCNT-bundled gel fibres were improved and their potential for tissue engineering applications as a cell scaffold was demonstrated. PMID:27200527

  1. Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers

    NASA Technical Reports Server (NTRS)

    Matthews, Kristopher; Cruden, Brett A.; Chen, Bin; Meyyappan, M.; Delzeit, Lance

    2002-01-01

    Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

  2. Hot wire production of single-wall and multi-wall carbon nanotubes

    DOEpatents

    Dillon, Anne C.; Mahan, Archie H.; Alleman, Jeffrey L.

    2010-10-26

    Apparatus (210) for producing a multi-wall carbon nanotube (213) may comprise a process chamber (216), a furnace (217) operatively associated with the process chamber (216), and at least one filament (218) positioned within the process chamber (216). At least one power supply (220) operatively associated with the at least one filament (218) heats the at least one filament (218) to a process temperature. A gaseous carbon precursor material (214) operatively associated with the process chamber (216) provides carbon for forming the multi-wall carbon nanotube (213). A metal catalyst material (224) operatively associated with the process (216) catalyzes the formation of the multi-wall carbon nanotube (213).

  3. Modeling Composites of Multi-Walled Carbon Nanotubes in Polycarbonate

    NASA Astrophysics Data System (ADS)

    Jindal, Prashant; Goyal, Meenakshi; Kumar, Navin

    2013-10-01

    High strain rate experiments performed on multi-walled carbon nanotubes, polycarbonate composites (MWCNT-PC) have exhibited enhanced impact resistance under a dynamic strain rate of nearly 2500/s with composition of only 0.5 to 2.0% multi-walled carbon nanotubes (MWCNTs) in pure polycarbonate (PC). Similarly, hardness and elastic modulus under static loads resulted in a significant increase, depending upon the composition of MWCNTs in PC. The present work aims to analyze these results by correlating the data to fit expressions in generalizing the behavior of MWCNTs composition for MWCNT-PC composites under both static and impact loads. As a result, we found that an optimum composition of 2.1 weight % of MWCNTs exhibits maximum stress resistance within elastic range under strain rates of nearly 2500/s for MWCNT-PC composites. The composition of MWCNTs plays a crucial role in maximizing modification of static and dynamic impact-based mechanical properties of polycarbonates. Further, a simple model based on Lennard-Jones 6-12 atom-atom based potential is formulated and used to compute preliminary estimates of static properties of pure as well as composite PC with the aim to modify this in subsequent approaches.

  4. Controlled modification of multiwalled carbon nanotubes with Zno nanostructures

    SciTech Connect

    Wang Xiuying; Xia Baiying; Zhu Xingfu; Chen Jiesheng; Qiu Shilun; Li Jixue

    2008-04-15

    Multiwalled carbon nanotubes (MWNTs) have been successfully modified with ZnO nanostructures by zinc-ammonitum complex ion covalently attached to the MWNTs through the C-N bonds. Flower-like ZnO on the tips of MWNTs and ZnO nanoparticles on the surface of MWNTs have been obtained, respectively, via adjusting the reaction time. The modified MWNTs have been characterized with X-ray diffraction, scanning electron and transmission electron microscopy. A growth mechanism has been proposed in which the soaking time plays a key role in controlling the size, morphology, and site of ZnO nanostructures. Photoluminescence properties of the as-synthesized products have also been investigated. - Multiwalled carbon nanotube (MWNT)/flower-like ZnO heterojunctions and MWNT/ZnO nanoparticle composites were prepared by zinc-ammonitum complex ion covalently attached to the MWNTs through the C-N bonds via adjusting the reaction time. A growth mechanism has been proposed in which the soaking time plays a key role in controlling the size, morphology, and site of ZnO nanostructures.

  5. Gate-controlled superconductivity in diffusive multiwalled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hakonen, Pertti

    2007-03-01

    We have investigated electrical transport in a diffusive, PECVD-grown multiwalled carbon nanotube contacted using superconducting leads made of Al/Ti sandwich structure. We find proximity-induced superconductivity with measured critical currents up to Icm= 1.3 nA, tunable by gate voltage. The supercurrent branch displays a finite zero bias resistance which varies as R0Icm^-α with α=0.74. We discuss the interpretation of these findings in terms of the RCSJ-model as well as the diffusive junction model for long SNS structures. In addition, we will compare the results with our recent data on proximity-induced supercurrents in singlewalled carbon nanotubes.

  6. Dislocation dynamics in multiwalled carbon nanotubes at high temperatures.

    PubMed

    Huang, J Y; Ding, F; Yakobson, B I

    2008-01-25

    Dislocation dynamics dictate the mechanical behavior of materials. Dislocations in periodic crystalline materials have been well documented. On the contrary, dislocations in cylindrical carbon nanotubes, particularly in multiwalled carbon nanotubes (MWCNTs), remain almost unexplored. Here we report that a room temperature 1/2<0001> sessile dislocation in a MWCNT becomes highly mobile, as characterized by its glide, climb, and the glide-climb interactions, at temperatures of about 2000 degrees C. The dislocation glide leads to the cross-linking of different shells; dislocation climb creates nanocracks; and the interaction of two 1/2<0001> dislocations creates kinks. We found that dislocation loops act as channels for mass transport. These dislocation dynamics are drastically different from that in conventional periodic crystalline materials due to the cylindrical, highly anisotropic structures of MWCNTs. PMID:18232998

  7. Covalent conjugation of multi-walled carbon nanotubes with proteins.

    PubMed

    Yi, Changqing; Qi, Suijian; Zhang, Dawei; Yang, Mengsu

    2010-01-01

    Linkage of proteins to carbon nanotubes (CNTs) is fundamentally important for applications of CNTs in medicinal and biological fields, as well as in biosensor or chemically modulated nanoelectronic devices. In this contribution, we provide a detailed protocol for the synthesis and characterization of covalent CNT-protein adducts. Functionalization of multiwalled carbon nanotubes (MWCNTs) with proteins has been achieved by the initial carboxylation of MWCNTs followed by amidation with the desired proteins. Attenuated total reflection Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) measurements validated the presence of a covalent linkage between MWCNTs and proteins. The visualization of proteins on the surface of MWCNTs was furthermore achieved using atomic force microscopy (AFM). The protein-conjugated nanocomposites can also be assembled into multidimensional addressable heterostructures through highly specific biomolecular recognition system (e.g., antibody-antigen). PMID:20422377

  8. Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake

    PubMed Central

    Miralles, Pola; Johnson, Errin; Church, Tamara L.; Harris, Andrew T.

    2012-01-01

    Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l−1 CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe3O4-functionalized CNTs were prepared and studied using energy-filter mapping of Fe3O4. CNTs bearing Fe3O4 nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up. PMID:22977097

  9. Thermal expansion of multiwall carbon nanotube reinforced nanocrystalline silver matrix composite

    SciTech Connect

    Sharma, Manjula Sharma, Vimal; Pal, Hemant

    2014-04-24

    Multiwall carbon nanotube reinforced silver matrix composite was fabricated by novel molecular level mixing method, which involves nucleation of Ag ions inside carbon nanotube dispersion at the molecular level. As a result the carbon nanotubes get embedded within the powder rather than on the surfaces. Micro structural characterization by X- ray diffraction and scanning electron microscopy reveals that the nanotubes are homogeneously dispersed and anchored within the matrix. The thermal expansion of the composite with the multiwall nanotube content (0, 1.5 vol%) were investigated and it is found that coefficient of thermal expansion decreases with the addition of multiwall nanotube content and reduce to about 63% to that of pure Ag.

  10. Lithiation-induced embrittlement of multiwalled carbon nanotubes.

    PubMed

    Liu, Yang; Zheng, He; Liu, Xiao Hua; Huang, Shan; Zhu, Ting; Wang, Jiangwei; Kushima, Akihiro; Hudak, Nicholas S; Huang, Xu; Zhang, Sulin; Mao, Scott X; Qian, Xiaofeng; Li, Ju; Huang, Jian Yu

    2011-09-27

    Lithiation of individual multiwalled carbon nanotubes (MWCNTs) was conducted in situ inside a transmission electron microscope. Upon lithiation, the intertube spacing increased from 3.4 to 3.6 Å, corresponding to about 5.9% radial and circumferential expansions and ∼50 GPa tensile hoop stress on the outermost tube wall. The straight tube walls became distorted after lithiation. In situ compression and tension tests show that the lithiated MWCNTs were brittle with sharp fracture edges. Such a failure mode is in stark contrast with that of the pristine MWCNTs which are extremely flexible and fail in a "sword-in-sheath" manner upon tension. The lithiation-induced embrittlement is attributed to the mechanical effect of a "point-force" action posed by the intertubular lithium that induces the stretch of carbon-carbon bonds in addition to that by applied strain, as well as the chemical effect of electron transfer from lithium to the antibonding π orbital that weakens the carbon-carbon bond. The combined mechanical and chemical weakening leads to a considerable decrease of the fracture strain in lithiated MWCNTs. Our results provide direct evidence and understanding of the degradation mechanism of carbonaceous anodes in lithium ion batteries. PMID:21819128

  11. Control of growth mode of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Quang, Nguyen Hong; Kim, Do-Hyung

    2009-09-01

    We have conducted an experimental study to investigate the synthesis of multi-walled carbon nanotubes (CNTs) by a dc plasma-enhanced chemical vapour deposition (PECVD) technique. The synthesis of base and tip-type of CNTs was selectively controlled by changing the catalyst size, catalyst film thickness correlated with altering the NH3 pretreatment plasma current. These types of CNT showed distinctive properties in nanotube structure, growth rate and vertical alignment, which were confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and in situ optical interference measurement. The vertically aligned behaviour of CNT was systematically studied by using a fine-patterned catalyst layer with diverse critical dimensions. Freestanding single CNT was successfully realized by optimum tip-type CNT growth, conventional photolithography and wet-etch process.

  12. On the tensile strength distribution of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Barber, Asa H.; Andrews, Rodney; Schadler, Linda S.; Wagner, H. Daniel

    2005-11-01

    Individual multiwalled carbon nanotubes grown by chemical vapor deposition (CVD) were tensile tested within the chamber of an electron microscope using an atomic force microscope-based technique. Weibull-Poisson statistics could accurately model the nanotube tensile strength data. Weibull shape and scale parameters of 1.7 and 109GPa were obtained. The former reflects a wide variability in strength similar to that observed for high-modulus graphite fibers, while the latter indicates that the irregular CVD-grown tube wall structure requires, in some cases, higher breaking forces than more regular tube wall structures. This apparent strengthening mechanism is most likely caused by an enhanced interaction between the walls of the nanotube.

  13. Electric current distribution of a multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Chen, Li-Ying; Chen, Yu-Jyun; Chang, Chia-Seng

    2016-07-01

    The electric current distribution in a multiwall carbon nanotube (MWCNT) was studied by in situ measuring the electric potential along an individual MWCNT in the ultra-high vacuum transmission electron microscope (TEM). The current induced voltage drop along each section of a side-bonded MWCNT was measured by a potentiometric probe in TEM. We have quantitatively derived that the current on the outermost shell depends on the applied current and the shell diameter. More proportion of the total electronic carriers hop into the inner shells when the applied current is increased. The larger a MWCNT's diameter is, the easier the electronic carriers can hop into the inner shells. We observed that, for an 8 nm MWCNT with 10 μA current applied, 99% of the total current was distributed on the outer two shells.

  14. Magnetic Multi-Walled Carbon Nanotubes for Tumor Theranostics.

    PubMed

    Wang, Lei; Shi, Jinjin; Hao, Yongwei; Zhang, Panpan; Zhao, Yalin; Meng, Dehui; Li, Dong; Chang, Junbiao; Zhang, Zhenzhong

    2015-09-01

    Current diagnostic techniques do not reliably detect cancer at early stages, and traditional chemotherapy lacks specificity and causes systemic toxicity. To address these issues, multifunctional nanomaterials are becoming more widely studied as a means of cancer detection, therapy, and monitoring. Here, iron oxide (Fe3O4) nanoparticles were conjugated onto the surface of multi-walled carbon nanotubes (MWNTs), which were then modified with polyethylenimine (PEI) and polyethylene glycol (PEG) to improve their solubility and biocompatibility. Finally, human telomerase reverse transcriptase (hTERT) siRNA was loaded on the MWNT surface by electrostatic interaction to obtain a multifunctional delivery system (MWNT-Fe3O4-PEI-PEG/siRNA). This delivery system efficiently delivered siRNA, allowed targeting of certain sites by magnetic fields, facilitated photothermal heating by near infrared irradiation, and enabled magnetic resonance imaging, thereby indicating great potential for cancer theranostic applications. PMID:26485934

  15. Multiwalled Carbon Nanotubes Inhibit Tumor Progression in a Mouse Model.

    PubMed

    García-Hevia, Lorena; Villegas, Juan C; Fernández, Fidel; Casafont, Íñigo; González, Jesús; Valiente, Rafael; Fanarraga, Mónica L

    2016-05-01

    Understanding the molecular mechanisms underlying the biosynthetic interactions between particular nanomaterials with specific cells or proteins opens new alternatives in nanomedicine and nanotoxicology. Multiwalled carbon nanotubes (MWCNTs) have long been explored as drug delivery systems and nanomedicines against cancer. There are high expectations for their use in therapy and diagnosis. These filaments can translocate inside cultured cells and intermingle with the protein nanofilaments of the cytoskeleton, interfering with the biomechanics of cell division mimicking the effect of traditional microtubule-binding anti-cancer drugs such as paclitaxel. Here, it is shown how MWCNTs can trigger significant anti-tumoral effects in vivo, in solid malignant melanomas produced by allograft transplantation. Interestingly, the MWCNT anti-tumoral effects are maintained even in solid melanomas generated from paclitaxel-resistant cells. These findings provide great expectation in the development of groundbreaking adjuvant synthetic microtubule-stabilizing chemotherapies to overcome drug resistance in cancer. PMID:26866927

  16. Features of the oxidation of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Savilov, S. V.; Ivanov, A. S.; Chernyak, S. A.; Kirikova, M. N.; Ni, J.; Lunin, V. V.

    2015-11-01

    Features of the functionalization of multiwalled carbon nanotubes (MWCNTs) with a conical (Ni precursor) and cylindrical (Fe precursor) arrangement of graphene layers using various oxidizing agents are studied. The initial diameter of pyrolytically prepared tubes varies from 20 to 80 nm with a maximum at 40-45 nm and from 10 to 30 nm with a maximum at 18 nm in the first and second cases, respectively. Oxidative modification of the MWCNT surfaces is conducted using HNO3 and H2O2 with ultrasound activation, ozonation in a glow discharge plasma of oxygen, and treatment with liquid ozone. Thermal and elemental analyses and IR spectroscopy show that the highest content of functional groups is achieved in the samples treated with nitric acid, where the conical MWCNTs are subject to surface functionalization. It is concluded that in order to achieve a similar result, cylindrical tubes must be treated with liquid ozone.

  17. Microwave attenuation of multiwalled carbon nanotube-fused silica composites

    SciTech Connect

    Xiang Changshu; Pan Yubai; Liu Xuejian; Sun Xingwei; Shi Xiaomei; Guo Jingkun

    2005-09-19

    Multiwalled carbon nanotubes (MWCNTs) were used to convert radome materials to microwave absorbing materials. Dense MWCNT-fused silica composites were prepared by hot-pressing technique. The composites exhibit high complex permittivities at X-band frequencies, depending on the content of MWCNTs. The value of the loss tangent increases three orders over pure fused silica only by incorporating 2.5 vol % MWCNTs into the composites. The average magnitude of microwave transmission reaches -33 dB at 11-12 GHz in the 10 vol % MWCNT-fused silica composites, which indicates the composites have excellent microwave attenuation properties. The attenuation properties mainly originate from the electric loss of MWCNTs by the motion of conducting electrons.

  18. Freestanding Aligned Multi-walled Carbon Nanotubes for Supercapacitor Devices

    NASA Astrophysics Data System (ADS)

    Moreira, João Vitor Silva; Corat, Evaldo José; May, Paul William; Cardoso, Lays Dias Ribeiro; Lelis, Pedro Almeida; Zanin, Hudson

    2016-08-01

    We report on the synthesis and electrochemical properties of multi-walled carbon nanotubes (MWCNTs) for supercapacitor devices. Freestanding vertically-aligned MWCNTs and MWCNT powder were grown concomitantly in a one-step chemical vapour deposition process. Samples were characterized by scanning and transmission electron microscopies and Fourier transform infrared and Raman spectroscopies. At similar film thicknesses and surface areas, the freestanding MWCNT electrodes showed higher electrochemical capacitance and gravimetric specific energy and power than the randomly-packed nanoparticle-based electrodes. This suggests that more ordered electrode film architectures facilitate faster electron and ion transport during the charge-discharge processes. Energy storage and supply or supercapacitor devices made from these materials could bridge the gap between rechargeable batteries and conventional high-power electrostatic capacitors.

  19. Microwave conductance of aligned multiwall carbon nanotube textile sheets

    NASA Astrophysics Data System (ADS)

    Brown, Brian L.; Bykova, Julia S.; Howard, Austin R.; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2014-12-01

    Multiwall carbon nanotube (MWNT) sheets are a class of nanomaterial-based multifunctional textile with potentially useful microwave properties. To understand better the microwave electrodynamics, complex AC conductance measurements from 0.01 to 50 GHz were made on sheets of highly aligned MWNTs with the alignment texture both parallel and perpendicular to the microwave electric field polarization. In both orientations, the AC conductance is modeled to first order by a parallel frequency-independent conductance and capacitance with no inductive contribution. This is consistent with low-frequency diffusive Drude AC conduction up to 50 GHz, in contrast to the "universal disorder" AC conduction reported in many types of single-wall nanotube materials.

  20. Multiwalled Carbon Nanotubes at the Interface of Pickering Emulsions.

    PubMed

    Briggs, Nicholas M; Weston, Javen S; Li, Brian; Venkataramani, Deepika; Aichele, Clint P; Harwell, Jeffrey H; Crossley, Steven P

    2015-12-01

    Carbon nanotubes exhibit very unique properties in biphasic systems. Their interparticle attraction leads to reduced droplet coalescence rates and corresponding improvements in emulsion stability. Here we use covalent and noncovalent techniques to modify the hydrophilicity of multiwalled carbon nanotubes (MWCNTs) and study their resulting behavior at an oil-water interface. By using both paraffin wax/water and dodecane/water systems, the thickness of the layer of MWNTs at the interface and resulting emulsion stability are shown to vary significantly with the approach used to modify the MWNTs. Increased hydrophilicity of the MWNTs shifts the emulsions from water-in-oil to oil-in-water. The stability of the emulsion is found to correlate with the thickness of nanotubes populating the oil-water interface and relative strength of the carbon nanotube network. The addition of a surfactant decreases the thickness of nanotubes at the interface and enhances the overall interfacial area stabilized at the expense of increased droplet coalescence rates. To the best of our knowledge, this is the first time the interfacial thickness of modified carbon nanotubes has been quantified and correlated to emulsion stability. PMID:26549532

  1. Synthesis of multiwalled carbon nanotubes on fly ash derived catalysts.

    PubMed

    Dunens, Oscar M; MacKenzie, Kieran J; Harris, Andrew T

    2009-10-15

    Carbon nanotubes (CNTs) are an allotrope of carbon with unique properties that make them potentially useful in a vast range of applications. However, CNTs are predominantly produced using expensive and/or nonrecyclable catalyst supports, e.g., mesoporous silica and alumina. In this work, coal combustion fly ash, a bulk waste product with limited uses, was impregnated with iron nitrate and successfully used as a substrate to produce industrial grade multiwalled carbon nanotubes (MWNTs) by fluidized bed chemical vapor deposition. CNTs were analyzed using thermogravimetric analysis, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The most successful catalyst trialed at 650 degrees C using ethylene as a carbon source was a 5 wt % Fe fly ash catalyst, which produced a CNT yield in respect to metal loading of approximately 82.5%. The MWNTs had outer diameters of between 12 and 20 nm with a reasonable degree of wall graphitization (I(G)/I(D) of 1.17). Advantages of utilizing fly ash as a catalyst support are its availability at low cost at the megaton scale, its high thermal stability, and suitability for use in industrial fluidized bed reactors. Potential applications for the fly ash produced CNTs include use in composite materials. PMID:19921910

  2. Exchange of Surfactant by Natural Organic Matter on the Surfaces of Multi-Walled Carbon Nanotubes

    EPA Science Inventory

    The increasing production and applications of multi-walled carbon nanotubes (MWCNTs) have elicited concerns regarding their release and potential adverse effects in the environment. To form stable aqueous MWCNTs suspensions, surfactants are often employed to facilitate dispersion...

  3. Multiwalled Carbon Nanotube Dispersion Methods Affect Their Aggregation, Deposition, and Biomarker Response

    EPA Science Inventory

    To systematically evaluate how dispersion methods affect the environmental behaviors of multiwalled carbon nanotubes (MWNTs), MWNTs were dispersed in various solutions (e.g., surfactants, natural organic matter (NOM), and etc.) via ultrasonication (SON) and long-term stirring (LT...

  4. Synthesis of multiwalled carbon nanotube from different grades of carbon black using arc discharge method

    NASA Astrophysics Data System (ADS)

    Arora, Neha; Sharma, N. N.

    2016-04-01

    This paper describes the synthesis of nanotube from different grades (Tread * A(non-ASTM), N134,N121,N660 and N330)of carbon black using DC arc discharge method at 40A current for 60sec. Carbon black samples of different grades were procured from industry (Aditya Birla Science and Technology Limited, India). Scanning Electron Micrographs (SEM) of the deposited carbon nanostructures suggests that MWCNTs are formed at 40A and for a minimal exposure time of 60sec.The result formed indicates the N330 grade of carbon black gets converted to MWCNTs (Multiwall Carbon nanotube) as compared to other grades.

  5. Glucose biosensor based on multi-wall carbon nanotubes and screen printed carbon electrodes.

    PubMed

    Guan, Wen-Jun; Li, Yu; Chen, Yu-Quan; Zhang, Xiao-Bin; Hu, Gui-Quan

    2005-09-15

    This paper describes a disposable electrochemical biosensor for glucose monitoring. The sensor was based on multi-wall carbon nanotubes (MWCNTs) immobilized with glucose oxidase and upon screen printed carbon electrode. The effect of MWCNTs on the response of amperometric glucose oxidase electrode for glucose was examined. Results obtained, of interest for basic and applied biochemistry, represent a first step in construction of a MWCNT-enzyme electrode biosensor with potentialities for a successful application in the biosensor area. PMID:16076441

  6. Electromagnetic properties of texture composite materials based on hexagonal ferrites/multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Dotsenko, O. A.; Frolov, K. O.; Wagner, D. V.

    2016-02-01

    In this article, the frequency dependence of the absorption coefficient and electromagnetic losses of the composite based on ferrite powder and / or multi-walled carbon nanotubes are presented. The dielectric and magnetic losses in the composite were measured in the range of 0.01 - 20 GHz. It has been found to increase the absorption of electromagnetic radiation and increased losses in the samples containing multi-walled carbon nanotubes.

  7. Growth of vertically aligned multiwall carbon nanotubes columns

    NASA Astrophysics Data System (ADS)

    Shahzad, M. I.; Giorcelli, M.; Perrone, D.; Virga, A.; Shahzad, N.; Jagdale, P.; Cocuzza, M.; Tagliaferro, A.

    2013-06-01

    Capability of patterning carbon nanotubes (CNTs) growth is of tantamount importance for a number of applications ranging from thermal to electronic. This article reports on the columnar growth of vertically aligned multiwall carbon nanotubes (VA-MWCNTs) on patterned Silicon (Si) surface. We have developed procedures based on negative as well as positive masking approaches which allows the growth of predetermined MWCNTs patterns. We describe in detail the process steps leading to Si surface patterning. As quoted above, patterns are exploited to grow VA-MWCNTs. We have focused in particular on the growth of CNT pillars by chemical vapor despoition (CVD) technique at 850°C with camphor and ferrocene as carbon precursors and catalyst respectively. Field emission scanning electron microscopy (FESEM) is employed at low magnification to verify the correct patterning, and at high magnification to examine the surface morphology of CNTs pillars. The pillars are up to 2 mm high, their height being tailored through the deposition time. The diameter of each MWCNT is in the range 30-70 nm and the length is up to few hundred micrometers. The small CNT pillars produced, have several electrical and thermal applications. For instance they can be very useful for heat transfer systems as the lower thermal conductivity of fluids can be improved by the inclusion of nanotubes thanks to their peculiar 1-dimensional heat transfer characteristics.

  8. Composite yarns of multiwalled carbon nanotubes with metallic electrical conductivity.

    PubMed

    Randeniya, Lakshman K; Bendavid, Avi; Martin, Philip J; Tran, Canh-Dung

    2010-08-16

    Unique macrostructures known as spun carbon-nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multiwalled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room-temperature conductivities of about 5 x 10(2) S cm(-1). Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal-CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self-fuelled electrodeposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nanoparticles takes place. In particular, the Cu-CNT and Au-CNT composite yarns prepared by this method have metal-like electrical conductivities (2-3 x 10(5) S cm(-1)) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30-50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nanoparticles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications. PMID:20665629

  9. Transversely isotropic elastic properties of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shen, Lianxi; Li, Jackie

    2005-01-01

    Five independent effective elastic moduli of a transversely isotropic multiwalled carbon nanotube (MWNT) are studied by analyzing its deformations under four loading conditions, i.e., axial tension, torsional moment, in-plane biaxial tension, and in-plane tension-compression stress. Two distributions of the tension loading on the outermost tube and on all tubes are considered, which correspond to the tensile and compressive Young’s moduli. The general relations between the interwall stresses and strains are linearized due to the small strain condition, where the interwall stresses correspond to the variation of the interwall van der Waals forces. Three interwall elastic constants are used to characterize the linear relations associated with three basic interwall deformation modes, i.e., normal deformation in radial direction and two shear deformations in axial and circumferential directions. By taking each tube as a single-walled carbon nanotube, the analytical expressions for the interwall shear stress under the tensile loading on the outermost tube and five elastic moduli of a double-walled carbon nanotube are first obtained. Then, a replacement method is proposed to derive the corresponding expressions for the cases of more walls than two. These analytical expressions are plotted for the case of MWNT’s composed of armchair tubes, where the interwall elastic constants are approximated as the corresponding ones of the graphite. The effect of the wall number, diameter, chirality, and length of the MWNT on the shear stress and five elastic moduli are displayed and discussed.

  10. Optical Study of Liquid Crystal Doped with Multiwalled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Gharde, Rita A.; Thakare, Sangeeta Y.

    2014-11-01

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

  11. A mediatorless biosensor for putrescine using multiwalled carbon nanotubes.

    PubMed

    Rochette, J-F; Sacher, E; Meunier, M; Luong, J H T

    2005-01-15

    Poly(diallyldimethylammonium) chloride, having a capability of dispersing multiwalled carbon nanotubes (MWCNTs), permits the modification of electrode surfaces. Together with putrescine oxidase, a MWCNT modified glassy carbon electrode was constructed for the development of a mediatorless putrescine biosensor. Nanoscale "dendrites" of MWCNTs were reasoned to form a network, projecting outward from the electrode surface acting like bundled ultra-microelectrodes, thereby permitting access to the active site and facilitating direct electron transfer to the immobilized enzyme. Our biosensor was capable of efficiently monitoring the direct electroactivity of putrescine oxidase at the electrode surface. Direct electron transfer permits the detection of putrescine at negative potentials, circumventing the interference of endogenous ascorbic and uric acids, which often complicate the analysis of important compounds in plasma. Compared with the most common interfering species, such as spermine, spermidine, cadaverine, and histamine, a detection limit of 5 microM and a response 20 times greater were found for putrescine. Tests performed on plasma of cancerous mice demonstrated that the detection of putrescine could be carried out very quickly on mammalian plasma without previous purification. PMID:15620897

  12. Surface modification of multiwall carbon nanotubes by sulfonitric treatment

    NASA Astrophysics Data System (ADS)

    Gómez, Sofía; Rendtorff, Nicolás M.; Aglietti, Esteban F.; Sakka, Yoshio; Suárez, Gustavo

    2016-08-01

    Carbon nanotubes are widely used for electronic, mechanical, and optical devices due to their unique structural and quantum characteristics. The species generated by oxidation on the surface of these materials permit binding new reaction chains, which improves the dispersibility, processing and compatibility with other materials. Even though different acid treatments and applications of these CNT have been reported, relatively few research studies have focused on the relationship between the acid treatment and the formation of nanodefects, specific oxidized species or CNT surface defects. In this work, multiwall carbon nanotube (MWCNT) oxidation at 90 °C was characterized in order to determine the acid treatment effect on the surface. It was found that oxidized species are already present in MWCNT without an acid treatment, but there are not enough to cause water-based dispersion. The species were identified and quantified by infrared spectroscopy and X-ray photoelectron spectroscopy. Also, transmission electron microscopy observations showed not only modifications of the oxidized species, but also morphological damage on the surfaces of MWCNT after being subjected to the acid treatment. This effect was also confirmed by Raman spectroscopy. The acid treatment generates higher oxidized species, decreasing the zeta potential in the whole pH range.

  13. Turning refuse plastic into multi-walled carbon nanotube forest

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  14. Heat Dissipation for Microprocessor Using Multiwalled Carbon Nanotubes Based Liquid

    PubMed Central

    Trinh, Pham Van; Chuc, Nguyen Van; Khoi, Phan Hong; Minh, Phan Ngoc

    2013-01-01

    Carbon nanotubes (CNTs) are one of the most valuable materials with high thermal conductivity (2000 W/m · K compared with thermal conductivity of Ag 419 W/m · K). This suggested an approach in applying the CNTs in thermal dissipation system for high power electronic devices, such as computer processor and high brightness light emitting diode (HB-LED). In this work, multiwalled carbon nanotubes (MWCNTs) based liquid was made by COOH functionalized MWCNTs dispersed in distilled water with concentration in the range between 0.2 and 1.2 gram/liter. MWCNT based liquid was used in liquid cooling system to enhance thermal dissipation for computer processor. By using distilled water in liquid cooling system, CPU's temperature decreases by about 10°C compared with using fan cooling system. By using MWCNT liquid with concentration of 1 gram/liter MWCNTs, the CPU's temperature decreases by 7°C compared with using distilled water in cooling system. Theoretically, we also showed that the presence of MWCNTs reduced thermal resistance and increased the thermal conductivity of liquid cooling system. The results have confirmed the advantages of the MWCNTs for thermal dissipation systems for the μ-processor and other high power electronic devices. PMID:24453829

  15. Multi-walled carbon nanotubes with rectangular or square cross-section

    NASA Astrophysics Data System (ADS)

    Mizutani, Kanako; Kohno, Hideo

    2016-06-01

    Multi-walled carbon nanotubes with rectangular or square cross-section are formed. The nanotubes are about 50-200 nm in width, and their walls are around 5-30 nm thick. It is very likely that the rectangular cross-section is shaped simultaneously when nanotubes are formed from catalyst Fe nanoparticles during chemical vapor deposition process, and the shape is stabilized by the bonding between adjoining graphene layers in the multi-walled structure.

  16. Electrical properties of multiwalled carbon nanotube reinforced fused silica composites.

    PubMed

    Xiang, Changshu; Pan, Yubai; Liu, Xuejian; Shi, Xiaomei; Sun, Xingwei; Guo, Jingkun

    2006-12-01

    Multiwalled carbon nanotube (MWCNT)-fused silica composite powders were synthesized by solgel method and dense bulk composites were successfully fabricated via hot-pressing. This composite was characterized by XRD, HRTEM, and FESEM. MWCNTs in the hot-pressed composites are in their integrity observed by HRTEM. The electrical properties of MWCNT-fused silica composites were measured and analyzed. The electrical resistivity was found to decrease with the increase in the amount of the MWCNT loading in the composite. When the volume percentage of the MWCNTs increased to 5 vol%, the electrical resistivity of the composite is 24.99 omega cm, which is a decrease of twelve orders of value over that of pure fused silica matrix. The electrical resistivity further decreases to 1.742 omega. cm as the concentration of the MWCNTs increased to 10 vol%. The dielectric properties of the composites were also measured at the frequency ranging from 12.4 to 17.8 GHz (Ku band) at room temperature. The experimental results reveal that the dielectric properties are extremely sensitive to the volume percentage of the MWCNTs, and the permittivities, especially the imaginary permittivities, increase dramatically with the increase in the concentration of the MWCNTs. The improvement of dielectric properties in high frequency region mainly originates from the greatly increasing electrical properties of the composite. PMID:17256338

  17. Nanoporous silica membranes fabricated using multiwalled carbon nanotubes.

    PubMed

    Kim, Hun-Sik; Kwon, Ha Il; Yun, Young Soo; Bak, Hyeonseong; Yoon, Jin-San; Jin, Hyoung-Joon

    2011-05-01

    Nanoporous silica membranes were fabricated using 3-aminopropyltriethoxysilane (APS) and acyl chloride-functionalized multiwalled carbon nanotubes (MWCNTs). The amine groups of silane reacted with the functional groups (e.g., acid chloride) that were attached to the sidewall of the MWCNTs. The APS that was grafted to the sidewall of the MWCNTs was polymerized in order to coat the MWCNTs wall through heating. The thickness of the silica layer on the surface of the MWCNTs was controlled by adjusting the growth time of the SiO2 layer. Approximately 20 nm-sized pores were formed through the removal of the MWCNTs using a simple thermal process, but some traces of the MWCNTs still remained. The porous properties of the nanoporous silica membrane were analyzed from the nitrogen adsorption-desorption isotherms that were obtained using a surface area and porosimetry analyzer. The structure and composition of the silane-modified MWCNTs were characterized using scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy. PMID:21780471

  18. Mobility of Multi-walled Carbon Nanotubes in Porous Media

    NASA Astrophysics Data System (ADS)

    O'Carroll, D. M.; Liu, X.; Petersen, E.; Huang, Q.; Anderson, L.

    2007-12-01

    Engineered multi-walled carbon nanotubes (MWCNTs) are the subject of intense research and are expected to gain widespread usage in a broad variety of commercial products. However concerns have been raised regarding their potential environmental and health risks. The mobility of MWCNTs in porous media is examined in this study through one dimensional flow-through column experiments under conditions representative of subsurface and drinking water treatment systems. The goal of this work was to determine dominant MWCNT removal mechanisms and factors that control MWCNT transport. Results demonstrate that pore water velocity strongly influenced MWCNT transport, a result that stands in contrast to traditional colloid filtration theory, which suggests a relatively minor effect of flow velocity in comparison to Brownian diffusion. Experiments conducted at different ionic strengths indicate that both particle deposition and straining are important MWCNT removal mechanisms from the aqueous phase. Given these findings, traditional colloid filtration theory may not be appropriate for the prediction of MWCNT mobility in porous media. This may be due to the large aspect ratio of the MWCNTs and the importance of straining in MWCNT removal.

  19. Multi-walled carbon nanotube-based RF antennas

    NASA Astrophysics Data System (ADS)

    Elwi, Taha A.; Al-Rizzo, Hussain M.; Rucker, Daniel G.; Dervishi, Enkeleda; Li, Zhongrui; Biris, Alexandru S.

    2010-01-01

    A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible polymer substrates. The DC conductivity of the printed patches was measured by the four probe technique and the complex relative permittivity was measured by an Agilent E5071B probe. The commercial software package, CST Microwave Studio (MWS), was used to simulate the proposed antennas based on the measured constitutive parameters. An excellent agreement of less than 0.2% difference in resonant frequency is shown. Simulated and measured results were also compared against identical microstrip antennas that utilize copper conducting patches. The proposed MWCNT-based antennas demonstrate a 5.6% to 2.2% increase in bandwidth, with respect to their corresponding copper-based prototypes, without significant degradation in gain and/or far-field radiation patterns.

  20. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    The pristine multi-walled carbon nanotubes (MWCNTs) were oxidized by the ultrasonication process. The oxidized MWCNTs were characterized by the X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) and Fourier transform -Raman (FT-Raman) spectroscopic techniques. The XRD analysis confirms that the oxidized MWCNTs exist in a hexagonal structure and the sharp XRD peak corresponds to the (002) Bragg's reflection plane, which indicates that the MWCNTs have higher crystalline nature. The UV-Vis analysis confirms that the MWCNTs functionalized with the carboxylic acid. The red shift was observed corresponds to the D band in the Raman spectrum, which reveals that the reduced disordered graphitic structure of oxidized MWCNTs. The strong Raman peak was observed at 2563 cm-1 corresponds to the overtone of the D band, which is the characteristic vibrational mode of oxidized MWCNTs. The carboxylic acid functionalization of MWCNTs enhances the dispersibility, which paves the way for potential applications in the field of biosensors and targeted drug delivery.

  1. Biological effects of agglomerated multi-walled carbon nanotubes.

    PubMed

    Song, Zheng-Mei; Wang, Lin; Chen, Ni; Cao, Aoneng; Liu, Yuanfang; Wang, Haifang

    2016-06-01

    The physicochemical properties of nanomaterials play crucial roles in determining their biological effects. Agglomeration of nanomaterials in various systems is a common phenomenon, however, how agglomeration affects the biological consequence of nanomaterials has not been well investigated because of its complexity. Herein, we prepared variable sized agglomerates of oxidized multi-walled carbon nanotubes (O-MWCNTs) by using Ca(2+) and studied their cellular uptake and cytotoxicity in HeLa cells. We found the altered property of O-MWCNTs agglomerates could be controlled and adjusted by the amount of Ca(2+). Agglomeration remarkably facilitated the cellular uptake of O-MWCNTs at the initial contact stage, due to the easy contact of agglomerates with cells. But agglomeration did not induce evident cytotoxicity when the concentration of O-MWCNTs was less than 150μg/mL. That was assayed by cell proliferation, membrane integrity, apoptosis and ROS generation. This study suggests us that the biological behaviors of nanomaterials could be altered by their states of agglomeration. PMID:26930035

  2. Preparation and Characterization of PETI-330/Multiwalled Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    As part of an ongoing effort to incorporate multifunctionality into advanced composites, blends of PETI-330 and multi-walled carbon nanotubes (MWCNTs) were prepared, characterized and fabricated into moldings. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight percent by dry mixing the components in a ball mill. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, PETI-330/MWCNT samples were scaled up to 300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were made by injecting the mixtures at 260-280 C into an Invar tool followed by curing for 1 h at 371 C. The tool was designed to impart shear during the injection process in an attempt to achieve some alignment of the MWCNTs in the flow direction. Good quality moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of the MWCNTs were investigated using high-resolution scanning electron microscopy. The preparation and preliminary characterization of PETI-330/MWCNT composites will be discussed. Keywords: phenylethynyl terminated imides, high temperature polymers, nanocomposites, moldings

  3. Preparation and Characterization of PETI-330/Multiwalled Carbon Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Delozier, Donavon M.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    As part of an ongoing effort to incorporate multi-functionality into advanced composites, blends of PETI-330 and multi-walled carbon nanotubes (MWCNTs) were prepared, characterized and fabricated into moldings. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight percent by dry mixing the components in a ball mill. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, PETI-330/MWCNT samples were scaled up to approx. 300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were fabricated by injecting the mixtures at 260-280 C into a stainless steel tool followed by curing for 1 h at 371 C. The tool was designed to impart high shear during the injection process in an attempt to achieve some alignment of the MWCNTs in the flow direction. Good quality moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of the MWCNTs were investigated using high-resolution scanning electron microscopy and Raman spectroscopy. The preparation and preliminary characterization of PETI-330/MWCNT composites will be discussed. Keywords: phenylethynyl terminated imides, high temperature polymers, nanocomposites,

  4. Microwave conductance properties of aligned multiwall carbon nanotube textile sheets

    NASA Astrophysics Data System (ADS)

    Brown, Brian L.; Martinez, Patricia; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2015-07-01

    Understanding the conductance properties of multi-walled carbon nanotube (MWNT) textile sheets in the microwave regime is essential for their potential use in high-speed and high-frequency applications. To expand current knowledge, complex high-frequency conductance measurements from 0.01 to 50 GHz and across temperatures from 4.2 K to 300 K and magnetic fields up to 2 T were made on textile sheets of highly aligned MWNTs with strand alignment oriented both parallel and perpendicular to the microwave electric field polarization. Sheets were drawn from 329 and 520 μm high MWNT forests that resulted in different DC resistance anisotropy. For all samples, the microwave conductance can be modeled approximately by a shunt capacitance in parallel with a frequency-independent conductance, but with no inductive contribution. This is consistent with diffusive Drude conduction as the primary transport mechanism up to 50 GHz. Further, it is found that the microwave conductance is essentially independent of both temperature and magnetic field.

  5. Ionization Gas Sensor using Aligned Multiwalled Carbon Nanotubes Array

    SciTech Connect

    Kermany, A. R.; Mohamed, N. M.; Singh, B. S. M.

    2011-05-25

    The challenge with current conventional gas sensors which are operating using semiconducting oxides is their size. After the introduction of nanotechnology and in order to reduce the dimension and consequently the power consumption and cost, new materials such as carbon nanotubes (CNTs) are being introduced. From previous works and characterization results, it was proven that the CNTs based gas sensor has better sensitivity, selectivity and faster response time in compared with semiconducting oxides based gas sensors. As in this work, a fabrication and successful testing of an ionization-based gas sensor using aligned Multiwalled CNTs (MWCNTs) as sensing element is discussed, in which MWCNTs array and Al film are used as anode and cathode plates respectively with electrode separation ranging from 80 {mu}m to 140 {mu}m. Aligned MWCNTs array was incorporated into a sensor configuration in the gas chamber for testing of gases such as argon, air, and mixed gas of 2%H{sub 2} in air. Obtained results show that among the three gases, argon has the lowest breakdown voltage whilst air has the highest value and the breakdown voltage was found to decrease as the electrode spacing was reduced from 140 {mu}m to 80 {mu}m for all three gases.

  6. Reinforcing multiwall carbon nanotubes by electron beam irradiation

    SciTech Connect

    Duchamp, Martial; Meunier, Richard; Smajda, Rita; Mionic, Marijana; Forro, Laszlo; Magrez, Arnaud; Seo, Jin Won; Song, Bo; Tomanek, David

    2010-10-15

    We study the effect of electron beam irradiation on the bending modulus of multiwall carbon nanotubes grown by chemical vapor deposition. Atomic force microscopy observations of the nanotube deflection in the suspended-beam geometry suggest an internal, reversible stick-slip motion prior to irradiation, indicating presence of extended defects. Upon electron beam irradiation, nanotubes with an initial bending modulus exceeding 10 GPa initially get stiffer, before softening at high doses. Highly defective nanotubes with smaller initial bending moduli do not exhibit the initial reinforcement. These data are explained by ab initio molecular dynamics calculations suggesting a spontaneous cross-linking of neighboring nanotube walls at extended vacancy defects created by the electron beam, in agreement with electron microscopy observations. At low defect concentration, depending on the edge morphology, the covalent bonds between neighboring nanotube walls cause reinforcement by resisting relative motion of neighboring walls. At high concentration of defects that are present initially or induced by high electron beam dose, the structural integrity of the entire system suffers from increasing electron beam damage.

  7. Surface studies of hydroxylated multi-wall carbon nanotubes

    SciTech Connect

    Bradley, Robert; Cassity, Kelby; Andrews, Rodney; Meier, Mark; Osbeck, Susan; Andreu, Aurik; Johnston, Colin; Crossley, Alison

    2012-01-01

    CVD grown MWCNTs, of typical diameter 5 to 50 nm and with approximately 15-20 concentric graphene layers in the multi-walls, have been surface functionalised using the Fenton hydroxylation reaction. HRTEM reveals little physical difference between the treated and untreated materials; images from both exhibit similar multi-wall structure and contain evidence for some low-level disruption of the very outermost layers. Raman spectra from the two types of nanotubes are almost identical displaying the disorder (D) peaks at approximately 1350 cm{sup -1} and graphite (G) peaks at approximately 1580 cm{sup -1}, characteristic of graphene-based carbon materials, in approximately equal intensity ratios. Equilibrium adsorption data for nitrogen at 77 K leads to BET surface areas of 60.4 m{sup 2} g{sup -1} for the untreated and 71.8 m{sup 2} g{sup -1} for the hydroxylated samples; the increase in area being due to separation of the tube-bundles during functionalization. This is accompanied by a decrease in measured porosity, mostly at high relative pressures of nitrogen, i.e. where larger (meso 2-5 nm and macro >5 nm) pores are being filled, which is consistent with an attendant loss of inter-tube capillarity. X-ray photoelectron spectroscopy (XPS) shows that hydroxylation increases the nanotube surface oxygen level from 4.3 at.% to 22.3 at.%; chemical shift data indicate that approximately 75% of that oxygen is present as hydroxyl (-OH) groups. Water vapour adsorption by the hydroxylated surfaces leads to Type II isotherms which are characteristic of relatively high numbers of hydrogen bonding interactions compared to the untreated materials which exhibit Type III curves. This difference in polar surface energy is confirmed by calorimetric enthalpies of immersion in water which are -54 mJ m{sup -2} for the untreated and -192 mJ m{sup -2} for the hydroxylated materials. The treated materials therefore have significantly increased water wettability/dispersivity and a greater

  8. Fabrication and characterization of the composites reinforced with multi-walled carbon nanotubes.

    PubMed

    Her, Shiuh-Chuan; Yeh, Shun-Wen

    2012-10-01

    Carbon nanotubes with superior mechanical, electrical and thermal properties have received intensive attention in recent years. In this study, multi-walled carbon nanotubes (MWCNT) were infused into a liquid epoxy, and the solution was sonicated for three hours to separate the aggregation of the MWCNTs and achieve good dispersion. The trapped air was removed from the mixture using a high vacuum. To investigate the effect of matrix stiffness on the mechanical properties of the MWCNT nanocomposites, the mixture ratio between the epoxy and hardener was varied. Two different contents (1% wt. and 2% wt.) of the multi-walled carbon nanotubes were added into the epoxy matrix. Tensile tests were conducted to determine the Young's modulus, yielding stress and tensile strength of the nanocomposites. The natural frequency and damping ratio of the nanocomposites were evaluated using free vibration tests. Experimental results show that the Young's modulus and natural frequency of MWCNT/epoxy nanocomposites increase with increase of the addition of multi-walled carbon nanotubes. While the damping ratio of the nanocomposites decreases with increase of the multi-walled carbon nanotubes. The reinforcement role of the multi-walled carbon nanotubes is less significant in a hard matrix when compares with a soft matrix. PMID:23421186

  9. Multiwalled carbon nanotube hybrids as MRI contrast agents.

    PubMed

    Kuźnik, Nikodem; Tomczyk, Mateusz Michał

    2016-01-01

    Magnetic resonance imaging (MRI) is one of the most commonly used tomography techniques in medical diagnosis due to the non-invasive character, the high spatial resolution and the possibility of soft tissue imaging. Contrast agents, such as gadolinium complexes and superparamagnetic iron oxides, are administered to spotlight certain organs and their pathologies. Many new models have been proposed that reduce side effects and required doses of these already clinically approved contrast agents. These new candidates often possess additional functionalities, e.g., the possibility of bioactivation upon action of particular stimuli, thus serving as smart molecular probes, or the coupling with therapeutic agents and therefore combining both a diagnostic and therapeutic role. Nanomaterials have been found to be an excellent scaffold for contrast agents, among which carbon nanotubes offer vast possibilities. The morphology of multiwalled carbon nanotubes (MWCNTs), their magnetic and electronic properties, the possibility of different functionalization and the potential to penetrate cell membranes result in a unique and very attractive candidate for a new MRI contrast agent. In this review we describe the different issues connected with MWCNT hybrids designed for MRI contrast agents, i.e., their synthesis and magnetic and dispersion properties, as well as both in vitro and in vivo behavior, which is important for diagnostic purposes. An introduction to MRI contrast agent theory is elaborated here in order to point to the specific expectations regarding nanomaterials. Finally, we propose a promising, general model of MWCNTs as MRI contrast agent candidates based on the studies presented here and supported by appropriate theories. PMID:27547627

  10. Multiwalled carbon nanotube hybrids as MRI contrast agents

    PubMed Central

    Tomczyk, Mateusz Michał

    2016-01-01

    Summary Magnetic resonance imaging (MRI) is one of the most commonly used tomography techniques in medical diagnosis due to the non-invasive character, the high spatial resolution and the possibility of soft tissue imaging. Contrast agents, such as gadolinium complexes and superparamagnetic iron oxides, are administered to spotlight certain organs and their pathologies. Many new models have been proposed that reduce side effects and required doses of these already clinically approved contrast agents. These new candidates often possess additional functionalities, e.g., the possibility of bioactivation upon action of particular stimuli, thus serving as smart molecular probes, or the coupling with therapeutic agents and therefore combining both a diagnostic and therapeutic role. Nanomaterials have been found to be an excellent scaffold for contrast agents, among which carbon nanotubes offer vast possibilities. The morphology of multiwalled carbon nanotubes (MWCNTs), their magnetic and electronic properties, the possibility of different functionalization and the potential to penetrate cell membranes result in a unique and very attractive candidate for a new MRI contrast agent. In this review we describe the different issues connected with MWCNT hybrids designed for MRI contrast agents, i.e., their synthesis and magnetic and dispersion properties, as well as both in vitro and in vivo behavior, which is important for diagnostic purposes. An introduction to MRI contrast agent theory is elaborated here in order to point to the specific expectations regarding nanomaterials. Finally, we propose a promising, general model of MWCNTs as MRI contrast agent candidates based on the studies presented here and supported by appropriate theories. PMID:27547627

  11. Multi-walled carbon nanotubes: sampling criteria and aerosol characterization

    PubMed Central

    Chen, Bean T.; Schwegler-Berry, Diane; McKinney, Walter; Stone, Samuel; Cumpston, Jared L.; Friend, Sherri; Porter, Dale W.; Castranova, Vincent; Frazer, David G.

    2015-01-01

    This study intends to develop protocols for sampling and characterizing multi-walled carbon nanotube (MWCNT) aerosols in workplaces or during inhalation studies. Manufactured dry powder containing MWCNT’s, combined with soot and metal catalysts, form complex morphologies and diverse shapes. The aerosols, examined in this study, were produced using an acoustical generator. Representative samples were collected from an exposure chamber using filters and a cascade impactor for microscopic and gravimetric analyses. Results from filters showed that a density of 0.008–0.10 particles per µm2 filter surface provided adequate samples for particle counting and sizing. Microscopic counting indicated that MWCNT’s, resuspended at a concentration of 10 mg/m3, contained 2.7 × 104 particles/cm3. Each particle structure contained an average of 18 nanotubes, resulting in a total of 4.9 × 105 nanotubes/cm3. In addition, fibrous particles within the aerosol had a count median length of 3.04 µm and a width of 100.3 nm, while the isometric particles had a count median diameter of 0.90 µm. A combination of impactor and microscopic measurements established that the mass median aerodynamic diameter of the mixture was 1.5 µm. It was also determined that the mean effective density of well-defined isometric particles was between 0.71 and 0.88 g/cm3, and the mean shape factor of individual nanotubes was between 1.94 and 2.71. The information obtained from this study can be used for designing animal inhalation exposure studies and adopted as guidance for sampling and characterizing MWCNT aerosols in workplaces. The measurement scheme should be relevant for any carbon nanotube aerosol. PMID:23033994

  12. The effects of multi-walled carbon nanotubes on soil microbial community functional and structural diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Applications of nanomaterials, including carbon nanotubes (CNTs), are increasing; however, their impact on the environment is still not well understood. A semi-arid soil was treated with multi-walled carbon nanotubes (MWCNTs) at four different concentrations (10-10000 mgMWCNTs kg-1soil), and incubat...

  13. Functionalized multi-walled carbon nanotubes in an aldol reaction

    NASA Astrophysics Data System (ADS)

    Chronopoulos, D. D.; Kokotos, C. G.; Karousis, N.; Kokotos, G.; Tagmatarchis, N.

    2015-01-01

    The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction between acetone and 4-nitrobenzaldehyde was evaluated for the first time, showing to proceed almost quantitatively in aqueous media. Furthermore, several amino-modified MWCNTs were prepared and examined in the particular aldol reaction. These new hybrid materials exhibited an enhanced catalytic activity in water, contrasting with the pristine MWCNTs as well as the parent organic molecule, which failed to catalyze the reaction efficiently. Furthermore, the modified MWCNTs proved to catalyze the aldol reaction even after three repetitive cycles. Overall, a green approach for the aldol reaction is presented, where water can be employed as the solvent and modified MWCNTs can be used as catalysts, which can be successfully recovered and reused, while their catalytic activity is retained.The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction

  14. 75 FR 44198 - Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes; Reopening of Comment Period

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-28

    ... public comment period established in the Federal Register of February 3, 2010 (75 FR 5546) (FRL-8796-7... AGENCY 40 CFR Part 721 RIN 2070-AB27 Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes... multi-walled carbon nanotubes (P-08-199). In order to address public comments, EPA is adding...

  15. Nanostructured copper phthalocyanine-sensitized multiwall carbon nanotube films.

    PubMed

    Hatton, Ross A; Blanchard, Nicholas P; Stolojan, Vlad; Miller, Anthony J; Silva, S Ravi P

    2007-05-22

    We report a detailed study of the interaction between surface-oxidized multiwall carbon nanotubes (o-MWCNTs) and the molecular semiconductor tetrasulfonate copper phthalocyanine (TS-CuPc). Concentrated dispersions of o-MWCNT in aqueous solutions of TS-CuPc are stable toward nanotube flocculation and exhibit spontaneous nanostructuring upon rapid drying. In addition to hydrogen-bonding interactions, the compatibility between the two components is shown to result from a ground-state charge-transfer interaction with partial charge transfer from o-MWCNT to TS-CuPc molecules orientated such that the plane of the macrocycle is parallel to the nanotube surface. The electronegativity of TS-CuPc as compared to unsubsubtituted copper phthalocyanine is shown to result from the electron-withdrawing character of the sulfonate substituents, which increase the molecular ionization potential and promote cofacial molecular aggregation upon drying. Upon spin casting to form uniform thin films, the experimental evidence is consistent with an o-MWCNT scaffold decorated with phthalocyanine molecules self-assembled into extended aggregates reminiscent of 1-D linearly stacked phthalocyanine polymers. Remarkably, this self-organization occurs in a fraction of a second during the spin-coating process. To demonstrate the potential utility of this hybrid material, it is successfully incorporated into a model organic photovoltaic cell at the interface between a poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester bulk heterojunction layer and an indium-tin oxide-coated glass electrode to increase the light-harvesting capability of the device and facilitate hole extraction. The resulting enhancement in power conversion efficiency is rationalized in terms of the electronic, optical, and morphological properties of the nanostructured thin film. PMID:17439261

  16. The hepatotoxicity of multi-walled carbon nanotubes in mice

    NASA Astrophysics Data System (ADS)

    Ji, Zongfei; Zhang, Danying; Li, Ling; Shen, Xizhong; Deng, Xiaoyong; Dong, Ling; Wu, Minhong; Liu, Yuanfang

    2009-11-01

    The hepatotoxicity of two types of multi-walled carbon nanotubes (MWCNTs), acid-oxidized MWCNTs (O-MWCNTs) and Tween-80-dispersed MWCNTs (T-MWCNTs), were investigated with Kunming mice exposed to 10 and 60 mg kg-1 by intravenous injection for 15 and 60 d. Compared with the PBS group, the body-weight gain of the mice decreased and the level of total bilirubin and aspartate aminotransferase increased in the MWCNT-exposed group with a significant dose-effect relationship, while tumor necrosis factor alpha level did not show significant statistical change within 60 d. Spotty necrosis, inflammatory cell infiltration in portal region, hepatocyte mitochondria swelling and lysis were observed with a significant dose-effect relationship in the MWCNT groups. Liver damage of the T-MWCNT group was more severe than that of the O-MWCNT group according to the Roenigk classification system. Furthermore, T-MWCNTs induce slight liver oxidative damage in mice at 15 d, which was recovered at 60 d. Part of the gene expressions of mouse liver in the MWCNT groups changed compared to the PBS group, including GPCRs (G protein-coupled receptors), cholesterol biosynthesis, metabolism by cytochrome P450, natural-killer-cell-mediated cytotoxicity, TNF- α, NF-κB signaling pathway, etc. In the P450 pathway, the gene expressions of Gsta2 (down-regulated), Cyp2B19 (up-regulated) and Cyp2C50 (down-regulated) had significant changes in the MWCNT groups. These results show that a high dose of T-MWCNTs can induce hepatic toxicity in mice while O-MWCNTs seem to have less toxicity.

  17. Buckling of Multiwall Carbon Nanotubes under Axial Compression

    NASA Astrophysics Data System (ADS)

    Akita, Seiji; Nishio, Mitsumasa; Nakayama, Yoshikazu

    2006-06-01

    We have investigated the axial buckling of multiwall nanotubes under the axial compression using nanomanipulation experiments and molecular dynamics (MD) simulations. Experimentally, Young’s moduli of nanotubes with different inner hollow diameters for the same outer diameters are consistent with the Eulers buckling model based on the continuum analysis. The MD simulations for the buckling behavior of triple- and double-walled nanotubes are also consistent with the continuum analysis. This good agreement indicates that Euler’s buckling model is applicable to the analysis of the axial buckling behavior of the multiwall nanotubes.

  18. Evaluation of Fibrogenic Potential of Industrial Multi-Walled Carbon Nanotubes in Acute Aspiration Experiment

    PubMed Central

    Khaliullin, T. O.; Shvedova, A. A.; Kisin, E. R.; Zalyalov, R. R.; Fatkhutdinova, L. M.

    2015-01-01

    Local inflammatory response in the lungs and fibrogenic potential of multi-walled carbon nanotubes were studied in an acute aspiration experiment in mice. The doses were chosen based on the concentration of nanotubes in the air at a workplace of the company-producer. ELISA, flow cytometry, enhanced darkfield microscopy, and histological examination showed that multi-walled carbon nanotubes induced local inflammation, oxidative stress, and connective tissue growth (fibrosis). Serum levels of TGF-β1 and osteopontin proteins can serve as potential exposure biomarkers. PMID:25778660

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

    PubMed

    Barzola-Quiquia, J; Klingner, N; Krüger, J; Molle, A; Esquinazi, P; Leonhardt, A; Martínez, M T

    2012-01-13

    We report on the electrical transport properties of single multiwall carbon nanotubes with and without an iron filling as a function of temperature and magnetic field. For the iron filled nanotubes the magnetoresistance shows a magnetic behavior induced by iron, which can be explained by taking into account a contribution of s-d hybridization. In particular, ferromagnetic-like hysteresis loops were observed up to 50 K for the iron filled multiwall carbon nanotubes. The magnetoresistance shows quantum interference phenomena such as universal conductance fluctuations and weak localization effects. PMID:22155967

  20. a Diffusive-Transport Approach to Determine the Electrical Conductance of AN Imperfect Multiwalled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Grado-Caffaro, Maria Angeles; Grado-Caffaro, Martin

    2014-05-01

    In this paper, we propose a diffusive-transport-based analytical formulation to calculate the linear electrical conductance through a multiwalled carbon nanotube with defects. In fact, on the one hand, by considerations on diffusive transport and, on the other hand, using the Drude model, we find out that the conductance (at Fermi energy) of an imperfect multiwalled carbon nanotube is approximately equal to the fundamental conductance quantum multiplied by the number of layers (or shells) of the tube. Our result agrees with experimental data.

  1. Structural and electrical properties of functionalized multiwalled carbon nanotube/epoxy composite

    NASA Astrophysics Data System (ADS)

    Gantayat, S.; Rout, D.; Swain, S. K.

    2016-05-01

    The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increased with increasing concentration of f-MWCNTs.

  2. Synthesis and characterization of polyaniline grafted multiwalled carbon nanotube loaded Nafion-silica nanocomposite membrane.

    PubMed

    Ragupathy, D; Gopalan, A; Kim, Kyeong-Wung; Lee, Kwang Pill

    2011-01-01

    The preparation and characterization results of a new nanocomposite, polyaniline (PANI) grafted multiwalled carbon nanotube (MWNT) loaded Nafion-silica, (designated as Nafion-silica/MWNT-g-PANI), are reported in this paper. The preparation involves the formation of a silica network in a Nafion membrane and the subsequent loading of polyaniline-grafted multiwalled carbon nanotubes (MWNT-g-PANI) onto the Nafion-silica nanocomposite. The new nanocomposite, Nafion-silica/ MWNT-g-PANI, was characterized as to its morphology, structure and properties. The conductivity and methanol permeability of the nanocomposite membranes were evaluated. PMID:21446537

  3. Numerical simulation of polarization beam splitter with triangular lattice of multi-walled carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Wu, Xingxing; Yun, Maojin; Wang, Mei; Liu, Chao; Li, Kai; Qin, Xiheng; Kong, Weijin; Dong, Lifeng

    2015-12-01

    A kind of polarization beam splitter with triangular lattice of multi-walled carbon nanotube arrays is designed and simulated. In the employed structure transverse-electric (TE) light is confined in the line defect with photonic band gap effect, while transverse-magnetic (TM) light is guided through it with extremely low diffraction. The performance of the designed polarization beam splitter is evaluated by utilizing optical properties of multi-walled carbon nanotubes, finite element modeling of wave propagation and transmission through periodic arrays. Simulation results indicate that the designed polarization beam splitter has low loss and less cross talk, and thereby may have practical applications in the integrated optical field.

  4. Determination of multi-walled carbon nanotube bioaccumulation in earthworms measured by a microwave-based detection technique

    EPA Science Inventory

    Reliable quantification techniques for carbon nanotubes (CNTs) are limited. In this study, a new procedure was developed for quantifying multi-walled carbon nanotubes (MWNTs) in earthworms (Eisenia fetida) based on freeze drying and microwave-induced heating. Specifically, earthw...

  5. The genotype-dependent influence of functionalized multiwalled carbon nanotubes on fetal development.

    PubMed

    Huang, Xinglu; Zhang, Fan; Sun, Xiaolian; Choi, Ki-Young; Niu, Gang; Zhang, Guofeng; Guo, Jinxia; Lee, Seulki; Chen, Xiaoyuan

    2014-01-01

    In many cases cancer is caused by gene deficiency that is being passed along from generation to generation. Soluble carbon nanotubes (CNTs) have shown promising applications in the diagnosis and therapy of cancer, however, the potential relationship between cancer-prone individuals and response to CNT exposure as a prerequisite for development of personalized nanomedicine, is still poorly understood. Here we report that intravenous injections of multi-walled carbon nanotubes into p53 (a well-known cancer-susceptible gene) heterozygous pregnant mice can induce p53- dependent responses in fetal development. Larger sized multi-walled carbon nanotubes moved across the blood-placenta barrier (BPB), restricted the development of fetuses, and induced brain deformity, whereas single-walled and smaller sized multi-walled carbon nanotubes showed no or less fetotoxicity. A molecular mechanism study found that multi-walled carbon nanotubes directly triggered p53-dependent apoptosis and cell cycle arrest in response to DNA damage. Based on the molecular mechanism, we also incorporated N-acetylcysteine (NAC), an FDA approved antioxidant, to prevent CNTs induced nuclear DNA damage and reduce brain development abnormalities. Our findings suggest that CNTs might have genetic background-dependent toxic effect on the normal development of the embryo, and provide new insights into protection against nanoparticle-induced toxicity in potential clinical applications. PMID:24344357

  6. The genotype-dependent influence of functionalized multiwalled carbon nanotubes on fetal development

    PubMed Central

    Huang, Xinglu; Zhang, Fan; Sun, Xiaolian; Choi, Ki Young; Niu, Gang; Zhang, Guofeng; Guo, Jinxia; Lee, Seulki; Chen, Xiaoyuan

    2013-01-01

    In many cases cancer is caused by gene deficiency that is being passed along from generation to generation. Soluble carbon nanotubes (CNTs) have shown promising applications in the diagnosis and therapy of cancer, however, the potential relationship between cancer-prone individuals and response to CNT exposure as a prerequisite for development of personalized nanomedicine, is still poorly understood. Here we report that intravenous injections of multi-walled carbon nanotubes into p53 (a well-known cancer susceptible gene) heterozygous pregnant mice can induce p53- dependent responses in fetal development. Larger sized multi-walled carbon nanotubes moved across the blood-placenta barrier (BPB), restricted the development of fetuses, and induced brain deformity, whereas single-walled and smaller sized multi-walled carbon nanotubes showed no or less fetotoxicity. A molecular mechanism study found that multi-walled carbon nanotubes directly triggered p53-dependent apoptosis and cell cycle arrest in response to DNA damage. Based on the molecular mechanism, we also incorporated N-acetylcysteine (NAC), a FDA approved antioxidant, to prevent CNTs induced nuclear DNA damage and reduce brain development abnormalities. Our findings suggest that CNTs might have genetic background-dependent toxic effect on the normal development of the embryo, and provide new insights into protection against nanoparticle-induced toxicity in potential clinical applications. PMID:24344357

  7. Multiwalled carbon nanotube CVD synthesis, modification, and composite applications

    NASA Astrophysics Data System (ADS)

    Qian, Dali

    Well-aligned carbon multiwall nanotube (MWNT) arrays have been continuously synthesized by a floating catalytic chemical vapor deposition (CVD) method involving the pyrolysis of xylene-ferrocene mixtures. The CVD parameters have been studied to selectively synthesize nanotubes with required dimensions. A mixed tip-root growth model has been proposed for the floating catalytic CVD synthesis. Coarsening of the catalyst particle at the root end promoted MWNT wall coarsening (addition of new concentric graphene shells), while the smaller catalyst particle at the tip contributed to MWNT elongation. A two-step process in which ferrocene was fed for only five minutes to nucleate the DTs was developed to understand if a continuous supply of catalyst was necessary for continued growth. The results show that the ferrocene was only necessary for initial nucleation. To simplify the CVD process further, another two-step synthesis method was developed in which the ferrocene was pre-decomposed so that the nanotube nucleation could be isolated from the growth, enabling quantification of growth mechanisms and kinetics. Mass spectra and hydrocarbon analyses of the CVD reactor tail gas were performed to understand the pyrolysis chemistry. Well-aligned N-doped and Ru-doped MWNT arrays have been produced by pyrolysis of pyridine ferrocene mixtures and xylene-ferrocene-ruthenocene mixtures, respectively. Various material characterization techniques were used to measure the dopant distributions and correlate the catalyst phase with the novel nanotube structures. High-temperature annealing has been shown to be a viable means to remove both the catalyst particles and certain microstructural defects within the CVD-derived DTs. The phase transformation of catalyst during annealing has also been studied. Homogeneous distribution of MWNTs in polystyrene matrices was achieved by an ultrasonic assisted solution-evaporation method. Addition of only 1 wt % DTs to polystyrene increased the polymer

  8. Infrared photoluminescence of composite films containing quasi-isolated multiwalled carbon nanotubes and carbon nanoshells.

    PubMed

    Reyes-Reyes, M; Segura-Cardenas, E; Gorbatchev, A Yu; López-Sandoval, R

    2010-07-01

    Films of small irregular-shaped aggregates composed by several layers of turbostratic graphite encapsulating iron nanoparticles, like carbon nanoshells, and quasi-isolated multi-walled carbon nanotubes (MWCNTs), were synthesized by the chemical vapor deposition method on glass substrates. Quasi-isolated MWCNTs were found emerging in different directions on the agglomerates composed of carbon nanoshells. The morphological properties of the films were characterized using scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy, whereas their optical properties were investigated using optical absorption and photoluminescence (PL) spectroscopy. The studies show a high-intensity PL signal in the infrared at room temperature. This PL signal shows several peaks, which cannot be explained by a blackbody emission. However, the overall PL signal could be a combination of the black emission and electronic transitions. Furthermore, the observed infrared PL emission could be ideal for potential applications such as in gas sensors, infrared detectors and so on. PMID:21128424

  9. A comparative study of EMI shielding properties of carbon nanofiber and multi-walled carbon nanotube filled polymer composites.

    PubMed

    Yang, Yonglai; Gupta, Mool C; Dudley, Kenneth L; Lawrence, Roland W

    2005-06-01

    Electromagnetic interference shielding properties of carbon nanofiber- and multi-walled carbon nanotube-filled polystyrene composites were investigated in the frequency range of 8.2-12.4 GHz (X-band). It was observed that the shielding effectiveness of composites was frequency independent, and increased with the increase of carbon nanofiber or nanotube loading. At the same filler loading, multi-walled carbon nanotube-filled polystyrene composites exhibited higher shielding effectiveness compared to those filled with carbon nanofibers. In particular, carbon nanotubes were more effective than nanofibers in providing high EMI shielding at low filler loadings. The experimental data showed that the shielding effectiveness of the composite containing 7 wt% carbon nanotubes could reach more than 26 dB, implying that such a composite can be used as a potential electromagnetic interference shielding material. The dominant shielding mechanism of carbon nanotube-filled polystyrene composites was also discussed. PMID:16060155

  10. Comprehensive Environmental Assessment Applied to Multiwalled Carbon Nanotube Flame-Retardant Coatings in Upholstery Textiles: A Case Study Presenting Priority Research Gaps for Future Risk Assessments (Final Report)

    EPA Science Inventory

    multiwalled_cover.jpg" alt="Cover of the Multiwalled Carbon Nanotube Case Study Final Report" vspace = "5" hspace="5" align="right" border="1" /> This final report presents a case study of multiwalled carbon nanotube...

  11. Enhanced sensing of NH3 gas by decorated multiwalled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hasnahena, S. T.; Satpati, Biswarup; Roy, Madhusudan

    2016-05-01

    The present study describes synthesis of Barium Oxide Nanoparticles decorated Multiwalled Carbon Nanotubes and its gas sensing behavior towards NH3 and CO gases. The decorated MWCNT sensor has an enhanced sensing towards NH3 gas compare to pure MWCNT sensor and also has much reduced response and recovery time. The prepared sensing material is characterized by TEM, XRD and Thermal Gravimetric analysis.

  12. 40 CFR 721.10276 - Multi-walled carbon nanotubes (generic) (P-10-39).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., metal, glass, or ceramic form that is not intended to undergo further processing except for mechanical processing. (2) The significant new uses are: (i) Protection in the workplace. Requirements as specified in... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes...

  13. 40 CFR 721.10279 - Multi-walled carbon nanotubes (generic) (P-10-246).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Multi-walled carbon nanotubes (generic) (P-10-246). 721.10279 Section 721.10279 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances §...

  14. Fabrication of high-performance flexible alkaline batteries by implementing multiwalled carbon nanotubes and copolymer separator.

    PubMed

    Wang, Zhiqian; Wu, Zheqiong; Bramnik, Natalia; Mitra, Somenath

    2014-02-12

    A flexible alkaline battery with multiwalled carbon nanotube (MWCNT) enhanced composite electrodes and polyvinyl alcohol (PVA)-poly (acrylic acid) (PAA) copolymer separator has been developed. Purified MWCNTs appear to be the most effective conductive additive, while the flexible copolymer separator not only enhances flexibility but also serves as electrolyte storage. PMID:24510667

  15. Limited transport of functionalized multi-walled carbon nanotubes in two natural soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment...

  16. 77 FR 39236 - Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-02

    ...EPA is announcing a 60-day public comment period for the external review draft document titled, ``Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether Flame-Retardant Coatings Applied to Upholstery Textiles'' (EPA/600/R- 12/043A). The draft document is being issued by the National Center for Environmental Assessment (NCEA) within EPA's Office of......

  17. Planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as stationary phase

    NASA Astrophysics Data System (ADS)

    Platonov, I. A.; Platonov, V. I.; Pavelyev, V. S.

    2016-04-01

    The high selectivity of the adsorption layer for low-boiling alkanes is shown, the separation factor (α) couple iso-butane / butane is 1.9 at a column temperature of 50 °C.The paper presents sorption and selective properties of planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as the stationary phase.

  18. Diffusion, swelling and electrical properties of polyisoprene/multiwall carbon nanotube composites in organic solvent vapours.

    PubMed

    Knite, M; Sakale, G; Teteris, V

    2012-10-01

    Polyisoprene/nanostructured carbon composites have been fabricated utilizing multiwall carbon nanotubes and carbon black nanoparticles as electrically conductive filler materials. Simultaneous measurements of (1) absorbed mass of organic solvent vapours (OSV), (2) swelling predicted elongation of sample and (3) electrical resistance changes versus the time of the presence of polyisoprene/multiwall carbon nanotube composites (PCNTC) in the OSV ambience were carried out by an in-house computerized setup. Non-Fickian anomalous diffusion has been found for all PCNTC samples as well as for reference samples of polyisoprene/high structure carbon black composites (PCBC). Obtained results indicate that the filler material content can play a substantial role in vapour diffusion into the composite. An advanced tunneling-percolation model was developed and used for describing of the OSV sensing effect in PCNTC and PCBC. PMID:23421188

  19. Effect of pulsed ion irradiation on the electronic structure of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bolotov, V. V.; Korusenko, P. M.; Nesov, S. N.; Povoroznyuk, S. N.

    2014-04-01

    The effect of pulsed ion irradiation and vacuum annealing on the ratio of sp 2- and sp 3-hybridized orbitals of carbon atoms in the layers of oriented multi-walled carbon nanotubes has been studied by analyzing the photoemission spectra of the C1 s core level and the valence band of carbon, which were obtained using the equipment of the BESSY II Russian-German beamline of synchrotron radiation and a Riber analytical system. It has been shown that the ion irradiation leads to a significant decrease in the fraction of atoms with the sp 3 hybridization of electrons. On the contrary, the annealing reduces the fraction of the sp 3-component in the spectra of carbon. Typical features of the valence band of multi-walled carbon nanotubes in the annealed and irradiated states have been established.

  20. 40 CFR 721.10277 - Single-walled and multi-walled carbon nanotubes (generic) (P-10-40).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... not intended to undergo further processing except for mechanical processing. (2) The significant new... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Single-walled and multi-walled carbon... Significant New Uses for Specific Chemical Substances § 721.10277 Single-walled and multi-walled...

  1. A Multi-Walled Carbon Nanotube-based Biosensor for Monitoring Microcystin-LR in Sources of Drinking Water Supplies

    EPA Science Inventory

    A multi-walled carbon nanotube-based electrochemical biosensor is developed for monitoring microcystin-LR (MC-LR), a toxic cyanobacterial toxin, in sources of drinking water supplies. The biosensor electrodes are fabricated using dense, mm-long multi-walled CNT (MWCNT) arrays gro...

  2. Effect of multi-walled carbon nanotubes and conducting polymer on capacitance of mesoporous carbon electrode.

    PubMed

    Wang, Anmiao; Cheng, Yingwen; Zhang, Hongbo; Hou, Ye; Wang, Yanqin; Liu, Jie

    2014-09-01

    Porous carbon is the most widely used electrode materials in energy storage devices. It is generally accepted that in such electrodes, mesoporosity is more desired in supercapacitor than microporosity for the ions tranportation. However, the relatively poor conductivity of porous carbon often leads to low capacitance. To improve the capacity of mesoporous carbon based electrode, we designed a composite film composed of mesoporous carbon, multiwalled carbon nanotubes (MWNTs) and conducting polymer, Poly-3,4-ethylenedioxythiophene/poly(styrenesulfonate) (PEDOT-PSS), and hoped that each component in the composed film could contribute synergetically to improve electrochemical properties. The electrochemical performance of the film was evaluated by cyclic voltammetry and constant current charge/discharge method. With the assistance of MWNTs and conducting polymer, the specific capacitance of the mesoporous carbon based electrode was amplified six times. The electrode also presented excellent charge/discharge rate and good cycling stability, retaining about 94% of its initial capacitance after 1000 cycles. The results demonstrated that mesoporous carbon is more effectively utilized with assistance of MWNTs and conducting polymer in the electrode. Such method is very promising for the future applications of the porous carbon in electrode materials for high performance electrochemical supercapacitors. PMID:25924364

  3. Mechanical buckling of multi-walled carbon nanotubes: The effects of slenderness ratio

    NASA Astrophysics Data System (ADS)

    Lu, Jian-Ming; Hwang, Chi-Chuang; Kuo, Qu-Yuan; Wang, Yun-Che

    2008-03-01

    Buckling strengths, in terms of compressive strain, of single-, double- and triple-walled carbon nanotubes (CNTs) are investigated to study the effects of slenderness ratio ( SR) via the molecular dynamics (MD) simulations with the Tersoff potential. Under constant ratio of slenderness, the CNTs with small SR behave like a continuum shell object. For large SR's, multi-walled CNTs exhibit the characteristics of the Euler columns. In addition, smaller nanotubes possess higher buckling-resistance. The buckling strength of multi-walled nanotubes is controlled by the size of their outermost shell.

  4. In situ tuning and probing the ambipolar field effect on multiwall carbon nanotubes

    SciTech Connect

    Chen, Li-Ying; Chang, Chia-Seng

    2014-12-15

    We report a method of fabricating ultra-clean and hysteresis-free multiwall carbon nanotube field-effect transistors (CNFETs) inside the ultra-high vacuum transmission electron microscope equipped with a movable gold tip as a local gate. By tailoring the shell structure of the nanotube and varying the drain-source voltage (V{sub ds}), we can tune the electronic characteristic of a multiwall CNFET in situ. We have also found that the Schottky barriers of a multiwall CNFET are generated within the nanotube, but not at the nanotube/electrode contacts, and the barrier height has been derived. We have subsequently demonstrated the ambipolar characteristics of the CNFET with concurrent high-resolution imaging and local gating.

  5. [Comparison study on adsorption of middle molecular substances with multiwalled carbon nanotubes and activated carbon].

    PubMed

    Li, Guifeng; Wan, Jianxin; Huang, Xiangqian; Zeng, Qiao; Tang, Jing

    2011-08-01

    In recent years, multi-walled carbon nanotubes (MWCTs) are very favorable to the adsorption of middle molecular substances in the hemoperfusion because of their multiporous structure, large surface area and high reactivity, which are beneficial to the excellent absorption properties. The purpose of this study was to study the MWCTs on the adsorption capacity of the middle molecular substances. Vitamin B12 (VB12) was selected as a model of the middle molecular substances. The morphologies of MWCTs and activated carbon from commercial "carbon kidney" were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption behavior of VB12 was compared to each other with UV-visible absorption spectra. The MWCTs formed a sophistaicate gap structure, and compared to the activated carbon, MWCTs had a larger surface area. By Langmuir equation and Freundlich equation fitting analysis, VB12 adsorption on MWCTs is fit for multi-molecular layer adsorption, and the adsorption type of activated carbon is more inclined to the model corresponding to Langmuir monolayer adsorption. The adsorption rate of MWCTs is faster than that of the activated carbon and the adsorption capacity is greater, which could be expected to become the new adsorbent in the hemoperfusion. PMID:21936376

  6. Fabrication and Characterization of Multi-Walled Carbon Nanotube (MWCNT) and Ni-Coated Multi-Walled Carbon Nanotube (Ni-MWCNT) Repair Patches for Carbon Fiber Reinforced Composite Systems

    NASA Technical Reports Server (NTRS)

    Johnson, Brienne; Caraccio, Anne; Tate, LaNetra; Jackson, Dionne

    2011-01-01

    Multi-walled carbon nanotube (MWCNT)/epoxy and nickel-coated multi-walled carbon nanotube (Ni-MWCNT)/epoxy systems were fabricated into carbon fiber composite repair patches via vacuum resin infusion. Two 4 ply patches were manufactured with fiber orientations of [90/ 90/ 4590] and [0/90/ +45/ -45]. Prior to resin infusion, the MWCNT/Epoxy system and NiMWCNT/ epoxy systems were optimized for dispersion quality. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to determine the presence ofcarbon nanotubes and assess dispersion quality. Decomposition temperatures were determined via thermogravametric analysis (TGA). SEM and TGA were also used to evaluate the composite repair patches.

  7. Nanoscale zirconia as a nonmetallic catalyst for graphitization of carbon and growth of single- and multiwall carbon nanotubes.

    PubMed

    Steiner, Stephen A; Baumann, Theodore F; Bayer, Bernhard C; Blume, Raoul; Worsley, Marcus A; MoberlyChan, Warren J; Shaw, Elisabeth L; Schlögl, Robert; Hart, A John; Hofmann, Stephan; Wardle, Brian L

    2009-09-01

    We report that nanoparticulate zirconia (ZrO(2)) catalyzes both growth of single-wall and multiwall carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD) and graphitization of solid amorphous carbon. We observe that silica-, silicon nitride-, and alumina-supported zirconia on silicon nucleates single- and multiwall carbon nanotubes upon exposure to hydrocarbons at moderate temperatures (750 degrees C). High-pressure, time-resolved X-ray photoelectron spectroscopy (XPS) of these substrates during carbon nanotube nucleation and growth shows that the zirconia catalyst neither reduces to a metal nor forms a carbide. Point-localized energy-dispersive X-ray spectroscopy (EDAX) using scanning transmission electron microscopy (STEM) confirms catalyst nanoparticles attached to CNTs are zirconia. We also observe that carbon aerogels prepared through pyrolysis of a Zr(IV)-containing resorcinol-formaldehyde polymer aerogel precursor at 800 degrees C contain fullerenic cage structures absent in undoped carbon aerogels. Zirconia nanoparticles embedded in these carbon aerogels are further observed to act as nucleation sites for multiwall carbon nanotube growth upon exposure to hydrocarbons at CVD growth temperatures. Our study unambiguously demonstrates that a nonmetallic catalyst can catalyze CNT growth by thermal CVD while remaining in an oxidized state and provides new insight into the interactions between nanoparticulate metal oxides and carbon at elevated temperatures. PMID:19663436

  8. Synthesis and Characterization of Magnetic Metal-encapsulated Multi-walled Carbon Nanobeads

    PubMed Central

    2008-01-01

    A novel, cost-effective, easy and single-step process for the synthesis of large quantities of magnetic metal-encapsulated multi-walled carbon nanobeads (MWNB) and multi-walled carbon nanotubes (MWNT) using catalytic chemical vapour deposition of methane over Mischmetal-based AB3alloy hydride catalyst is presented. The growth mechanism of metal-encapsulated MWNB and MWNT has been discussed based on the catalytically controlled root-growth mode. These carbon nanostructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM and HRTEM), energy dispersive analysis of X-ray (EDAX) and thermogravimetric analysis (TGA). Magnetic properties of metal-filled nanobeads have been studied using PAR vibrating sample magnetometer up to a magnetic field of 10 kOe, and the results have been compared with those of metal-filled MWNT.

  9. Deformation and Failure of a Multi-Wall Carbon Nanotube Yarn Composite

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.

    2008-01-01

    Forests of multi-walled carbon nanotubes can be twisted and manipulated into continuous fibers or yarns that exhibit many of the characteristics of traditional textiles. Macro-scale analysis and test may provide strength and stiffness predictions for a composite composed of a polymer matrix and low-volume fraction yarns. However, due to the nano-scale of the carbon nanotubes, it is desirable to use atomistic calculations to consider tube-tube interactions and the influence of simulated twist on the effective friction coefficient. This paper reports laboratory test data on the mechanical response of a multi-walled, carbon nanotube yarn/polymer composite from both dynamic and quasi-static tensile tests. Macroscale and nano-scale analysis methods are explored and used to define some of the key structure-property relationships. The measured influence of hot-wet aging on the tensile properties is also reported.

  10. Enhanced rate performance of multiwalled carbon nanotube encrusted olivine type composite cathode material using polyol technique

    NASA Astrophysics Data System (ADS)

    Muruganantham, R.; Sivakumar, M.; Subadevi, R.

    2015-12-01

    Olivine type multi-walled carbon nanotube encrusted LiFePO4/C composites have been prepared using economic and energy efficient simple polyol technique without any subsequent heat treatment. The prepared material has an olivine type orthorhombic phase. Also, the iron oxidation state is 2+, which is identified by X-ray diffraction and X-ray photoelectron spectroscopy. It is possible to attain the discharge capacity almost close to theoretical capacity of LiFePO4 as in high temperature methods with ∼100% coulombic efficiency. The specific surface area has been increased upon encrusting multi walled carbon nano tube on LiFePO4/C, which results in enhanced reversible capacity upto 166 mAh g-1 at C/10. Also, it exhibits 89 mAh g-1 even at 30 C rate. This is due to the formation of conductive networks by carbon nanotube, and excellent attachment of LiFePO4/C composite particles on multi-walled carbon nanotube, which induced the kinetics during intercalation/deintercalation process. Multi-walled carbon nanotube acts as the electro-conductive filler on the LiFePO4 surface. The direct addition of MWCNT would result better performances than blending the MWCNT with LiFePO4/C.

  11. Characterization of fluorinated multiwalled carbon nanotubes by x-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Brzhezinskaya, M. M.; Vinogradov, N. A.; Muradyan, V. E.; Shul'Ga, Yu. M.; Polyakova, N. V.; Vinogradov, A. S.

    2008-03-01

    The C 1 s and F 1 s x-ray absorption spectra of fluorinated multiwalled carbon nanotubes with different fluorine contents and reference compounds (highly oriented pyrolytic graphite crystals and "white" graphite fluoride) were measured using the equipment of the Russian-German beamline at the BESSY II storage ring with a high energy resolution. The spectra obtained were analyzed with the aim of characterizing multiwalled carbon nanotubes and their products formed upon treatment of the nanotubes with fluorine at a temperature of 420°C. It was established that, within the probing depth (˜15 nm) of carbon nanotubes, the process of fluorination occurs uniformly and does not depend on the fluorine concentration. The interaction of fluorine atoms with multiwalled carbon nanotubes in this case proceeds through the covalent attachment of fluorine atoms to graphene layers of the graphite skeleton and is accompanied by a change in the hybridization of the 2 s and 2 p valence electron states of the carbon atom from the trigonal ( sp 2) to tetrahedral ( sp 3) hybridization.

  12. Enhanced preconcentration of selected chlorofluorocarbons on multiwalled carbon nanotubes with polar functionalities.

    PubMed

    Saridara, Chutarat; Hussain, Chaudhery Mustansar; Ragunath, Smruti; Mitra, Somenath

    2015-02-01

    Chromatographic monitoring of chlorofluorocarbons in air requires the preconcentration of these highly volatile species. In this paper, we present functionalized multiwalled carbon nanotubes as effective sorbents for a microtrap designed for chlorofluorocarbons preconcentration. Among the commercial carbons and carbon nanotubes studied, functionalization via carboxylation and propyl amine was most effective for dichlorofluoromethane and trichlorofluoromethane (Freon 11), which were selected as representative chlorofluorocarbons. The results show that carbon nanotubes functionalized with a polar groups led to as much as a 300% increase in breakthrough volume and the desorption bandwidth was reduced by 2.5 times. PMID:25403651

  13. Multiwalled Carbon Nanotube Forest Grown via Chemical Vapor Deposition from Iron Catalyst Nanoparticles, by XPS

    SciTech Connect

    Jensen, David S.; Kanyal, Supriya S.; Madaan, Nitesh; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Linford, Matthew R.

    2013-09-25

    Carbon nanotubes (CNTs) have unique chemical and physical properties. Herein, we report an XPS analysis of a forest of multiwalled CNTs using monochromatic Al Kα radiation. Survey scans show only one element: carbon. The carbon 1s peak is centered 284.5 eV. The C 1s envelope also shows the expected π → π* shake-up peak at ca. 291 eV. The valence band and carbon KVV Auger signals are presented. When patterned, the CNT forests can be used as a template for subsequent deposition of metal oxides to make thin layer chromatography plates.1-3

  14. Fabrication of one-dimensional Ag/multiwalled carbon nanotube nano-composite

    PubMed Central

    2012-01-01

    Composite made of multiwalled carbon nanotubes coated with silver was fabricated by an electroless deposition process. The thickness of silver layer is about 40 to 60 nm, characterized as nano-crystalline with (111) crystal orientation along the nanotube's axial direction. The characterization of silver/carbon nanotube [Ag/CNT] nanowire has shown the large current carrying capability, and the electric conductivity is similar to the pure silver nanowires that Ag/CNT would be promising as building blocks for integrated circuits. PACS: 81.05.uj, carbon nanotubes, carbon-based materials, diamond/nanocarbon composites. PMID:22444640

  15. Electrochemical biosensing of galactose based on carbon materials: graphene versus multi-walled carbon nanotubes.

    PubMed

    Dalkıran, Berna; Erden, Pınar Esra; Kılıç, Esma

    2016-06-01

    In this study, two enzyme electrodes based on graphene (GR), Co3O4 nanoparticles and chitosan (CS) or multi-walled carbon nanotubes (MWCNTs), Co3O4 nanoparticles, and CS, were fabricated as novel biosensing platforms for galactose determination, and their performances were compared. Galactose oxidase (GaOx) was immobilized onto the electrode surfaces by crosslinking with glutaraldehyde. Optimum working conditions of the biosensors were investigated and the analytical performance of the biosensors was compared with respect to detection limit, linearity, repeatability, and stability. The MWCNTs-based galactose biosensor provided about 1.6-fold higher sensitivity than its graphene counterpart. Moreover, the linear working range and detection limit of the MWCNTs-based galactose biosensor was superior to the graphene-modified biosensor. The successful application of the purposed biosensors for galactose biosensing in human serum samples was also investigated. PMID:27074783

  16. SEPARATION OF CO2 FROM FLUE GASES BY CARBON-MULTIWALL CARBON NANOTUBE MEMBRANES

    SciTech Connect

    Rodney Andrews

    2001-03-01

    Multiwalled carbon nanotubes (MWNT) were found to be an effective separation media for removing CO{sub 2} from N{sub 2}. The separation mechanism favors the selective condensation of CO{sub 2} from the flowing gas stream. Significant uptakes of CO{sub 2} were measured at 30 C and 150 C over the pressure range 0.5 to 5 bar. No measurable uptake of nitrogen was found for this range of conditions. The mass uptake of CO{sub 2} by MWNT was found to increase with increasing temperature. A packed bed of MWNT completely removed CO{sub 2} from a flowing stream of CO{sub 2}/N{sub 2}, and exhibited rapid uptake kinetics for CO{sub 2}.

  17. Growth of long and aligned multi-walled carbon nanotubes on carbon and metal substrates.

    PubMed

    Delmas, M; Pinault, M; Patel, S; Porterat, D; Reynaud, C; Mayne-L'Hermite, M

    2012-03-16

    Well aligned, long and dense multi-walled carbon nanotubes (CNT) can be grown on both carbon fibres and any metal substrates compatible with the CNT synthesis temperature. The injection-CVD process developed involves two stages, including fibre pretreatment by depositing a SiO(2)-based sub-layer from an organometallic precursor followed by CNT growth from toluene/ferrocene precursor mixture. Carbon substrates, as well as metals, can easily be treated with this process, which takes place in the same reactor and does not need any handling in between the two stages. The aligned CNT carpets obtained are similar to the ones grown on reference quartz substrates. The CNT growth rate is fairly high (ca. 30 μm min(-1)) and it is possible to control CNT length by varying the CNT synthesis duration. The thickness of the SiO(2)-based sub-layer can be varied and is shown to have an influence on the CNT growth. This layer is assumed to play a diffusion barrier layer role between the substrate and the iron based catalyst nanoparticles producing CNT. The CNT anchorage to the carbon fibres has been checked and good overall adhesion proved, which is in favour of a good transfer of electrical charge and heat between the nanotubes and fibre. PMID:22362164

  18. Effect of nitrogen-containing groups on enhanced capacitive behaviors of multi-walled carbon nanotubes

    SciTech Connect

    Kim, Ji-Il; Park, Soo-Jin

    2011-08-15

    In this work, electrochemical properties of surface treated multi-walled carbon nanotubes (MWNTs) are studied in supercapacitors. Nitrogen and oxygen functional groups containing MWNTs are prepared by urea and acidic treatments, respectively. The surface properties of the MWNTs are confirmed by X-ray photoelectron spectroscopy (XPS) and zeta-potential measurements. The textural properties are characterized by N{sub 2} adsorption/desorption isotherm at 77 K using the BET eqaution, BJH method, and HK method. The electrochemical properties of the MWNTs are accumulated by cyclic voltammetry, impedance spectra, and charge-discharge cycling performance in 1 M H{sub 2}SO{sub 4} at room temperature. As a result, the functionalized MWNTs lead to an increase in capacitance as compared with pristine MWNTs. It suggests that the pyridinic and pyridinic-N-oxides nitrogen species have effects on the specific capacitance due to the positive charge, and thus an improved electron transfer at high current loads results, the most important functional groups affecting capacitive behaviors. - Graphical Abstract: The N{sub 1s} spectra of nitrogen functionalized multi-walled carbon nanotubes are measured by X-ray photoelectron spectroscopy. Highlights: > Facile method of increasing elemental composition of nitrogen functional groups on carbon materials. > Increased specific capacitance multi-walled carbon nanotubes (MWNTs) for electrode materials as high as general chemical activation process. > Enhanced capacitive behaviors via introducing pyridinic and pyridinic-N-oxides nitrogen species onto the MWNTs. > Improvement of electron transfer at high current loads.

  19. Immobilization of Bovine Serum Albumin Upon Multiwall Carbon Nanotube for High Speed Humidity Sensing Application.

    PubMed

    Bhattacharya, Sankhya; Sasmal, Milan

    2016-01-01

    We present a high-speed humidity sensor based on immobilization of bovine serum albumin upon multiwall carbon nanotube (IBC). A simple and versatile drop casting technique was employed to make the humidity sensor using novel material IBC at room temperature. IBC was synthesized using easy solution process technique. The working principle of the IBC humidity sensor depends upon the variation of output current or conductance with the exposure of different humidity level. Humidity sensing properties of our device is explained on the basis of charge transfer from water molecules to IBC and bovine serum albumin to multiwall carbon nanotube (MWCNT). Our sensor exhibits faster response time around 1.2 s and recovery time 1.5 s respectively. PMID:26841403

  20. Synthesis and characterization of multiwalled carbon nanotube/IPMC actuator for imitating locomotion of gecko's toes

    NASA Astrophysics Data System (ADS)

    He, Qingsong; Yu, Min; Ding, Yan; Dai, Zhendong

    2012-04-01

    A multi-walled carbon nanotube (MCNT)/Nafion nanocomposite was fabricated by dispersion of treated MCNTs in a Nafion solution. The multi-walled carbon nanotube (MCNT) filler was prepared with the cationic surfactant cetyl trimethyl ammonium bromide. Starting from cast Nafion membranes, IPMCs were manufactured by electroless plating. The current and the blocking force were measured with an IPMC actuation testing apparatus. Compared with a bare Nafion-based IPMC, the blocking force of the new IPMC improved 1-1.4 times, and the current increased by 33%-67%. The clearly enhanced performance of the new MCNT filler-based IPMC is attributed to the well-distributed MCNTs that improved the electrical properties of the IPMC. Finally, the new IPMC was successfully employed to directly actuate gecko-inspired adhesive arrays that we fabricated by ourselves.

  1. Synthesis and characterization of polyvinyl alcohol based multiwalled carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Malikov, E. Y.; Muradov, M. B.; Akperov, O. H.; Eyvazova, G. M.; Puskás, R.; Madarász, D.; Nagy, L.; Kukovecz, Á.; Kónya, Z.

    2014-07-01

    Multiwalled carbon nanotubes were synthesized by chemical vapor deposition over an Fe-Co/alumina catalyst. Nanotubes were then oxidized and grafted with polyvinyl alcohol (PVA). The obtained nanostructure was characterized by Raman spectroscopy, XRD, FTIR, EDX, SEM, TEM and TGA methods. FTIR confirmed the presence of the characteristic peaks of the anticipated ester group. The formation of polymer nanocomposites based on polyvinyl alcohol and multiwalled carbon nanotubes was confirmed by SEM and TEM. High resolution electron micrographs revealed that the primary binding sites for PVA grafting are the sidewall defects of the nanotubes. The novelty of this work is the use of the Fischer esterification reaction for creating the permanent link between the nanotubes and the PVA matrix.

  2. Synthesis of Multi-Walled Carbon Nanotubes/TiO2 Composite and Its Photocatalytic Activity.

    PubMed

    Dong, Hongying; Qu, Caifeng; Zhang, Tingting; Zhu, Liwei; Ma, Wen

    2016-03-01

    TiO2 particles coated Multi-walled carbon nanotubes (MWCNT/TiO2 composite) were prepared via a sol-gel method using Multi-walled carbon nanotubes (MWCNT) and tetrabutyl titanate as raw materials. The phase constitutes and microstructures of the prepared composite were analyzed by XRD and TEM, respectively. Their photocatalytic activities were investigated under simulated ultra-violet light and visible-light irradiation for the degradation of methyl orange (MO) and methylene blue (MB) aqueous solution, respectively. The experimental results indicated that TiO2 calcined at temperatures of 400-600 degrees C in the MWCNT/TiO2 composite was mainly composed of nanometric anatase. The composite exhibited enhanced absorption properties in the visible-light region compared to pure TiO2, which was attributed to the enhanced light electron-hole separation by adding MWCNTs. PMID:27455683

  3. Multi-wall carbon nanotube@zeolite imidazolate framework composite from a nanoscale zinc oxide precursor

    DOE PAGESBeta

    Yue, Yanfeng; Guo, Bingkun; Qiao, Zhenan; Fulvio, Pasquale F.; Chen, Jihua; Binder, Andrew J.; Tian, Chengcheng; Dai, Sheng

    2014-07-24

    Nanocomposite of multi-walled carbon nanotube@zeolite imidazolate frameworks (MWNT@ZIF) was prepared through a nanotube-facilitated growth based on a nanosized ZnO precursor. The electrically conductive nanocomposite displays a capacity of 380 mAh/g at 0.1 °C in Li–sulfur battery, transforming electrically inactive ZIF into the active one for battery applications.

  4. Carboxyl multiwalled carbon nanotubes modified polypyrrole (PPy) aerogel for enhanced electromagnetic absorption

    NASA Astrophysics Data System (ADS)

    Zhang, Kun; Xie, Aming; Wu, Fan; Jiang, Wanchun; Wang, Mingyang; Dong, Wei

    2016-05-01

    Polypyrrole (PPy) aerogel is a low-cost and lightweight material with high-performance electromagnetic absorption (EA). However, it does not always meet the requirements of practical applications. In this study, we used trace amounts of carboxyl multiwalled carbon nanotubes to regulate the dielectric property of PPy aerogel, thus enhancing the EA performance. Furthermore, the reason for enhanced EA performance can be elaborated by an electron blocking mechanism.

  5. Synthesis of Meltspun Multiwall Carbon Nanotube/Polycarbonate Fibers Through Solvent Casting and Melt Extrusion.

    PubMed

    Yadav, Poonam; Park, Sang Whan; Lee, Dong Bok

    2015-11-01

    Films and strands consisting of polycarbonate (PC) containing 0.55 or 0.75 wt% multiwall carbon nanotubes (MWNTs) were synthesized through solvent casting and melt extrusion methods, respectively. They were further processed into fibers through melt spinning. Fibers made from melt-extruded strands exhibited a smoother surface, more uniform morphology, and better dispersion of MWNTs in PC than those made from solvent-cast films. PMID:26726657

  6. Structural ordering of multi-walled carbon nanotubes (MWCNTs) caused by gamma (γ)-ray irradiation

    SciTech Connect

    Silambarasan, D. Vasu, V.; Iyakutti, K.; Asokan, K.

    2015-06-24

    Multi-walled carbon nanotubes (MWCNTs) were irradiated by Gamma (γ)-rays in air with absorbed doses of 25 and 50 kGy. As a result of γ-ray irradiation, the inter-wall distance of MWCNTs was decreased and their graphitic order was improved. The reduction in inter-wall distance and structural ordering was improved with the increasing dosage of irradiation. Experimental evidences are provided by powder XRD and micro-Raman analyses.

  7. Mapping functional groups on oxidised multi-walled carbon nanotubes at the nanometre scale.

    PubMed

    Goode, A E; Hine, N D M; Chen, S; Bergin, S D; Shaffer, M S P; Ryan, M P; Haynes, P D; Porter, A E; McComb, D W

    2014-06-28

    Despite voluminous research on the acid oxidation of carbon nanotubes (CNTs), there is a distinct lack of experimental results showing distributions of functional groups at the nanometre length scale. Here, functional peaks have been mapped across individual multi-walled CNTs with low-dose, monochromated electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). Density functional theory simulations show that the EELS features are consistent with oxygenated functional groups, most likely carboxyl moieties. PMID:24827593

  8. Origin of enhanced field emission characteristics postplasma treatment of multiwalled carbon nanotube array

    SciTech Connect

    Lee, Kyu; Lim, Seong Chu; Lee, Young Hee; Choi, Young Chul

    2008-08-11

    Field emission properties of chemical-vapor-deposition-grown multiwalled carbon nanotubes (MWCNTs) with plasma treatment have been investigated. Origin of the enhanced field emission current was interpreted in terms of surface morphology of MWCNTs, work function, field enhancement factor, and emission area. Contrary to the general belief, the change in the work function increased slightly with the plasma treatment time, whereas the field enhancement factor decreased. We found that the number of emittable MWCNTs played a dominant role in the current enhancement.

  9. Pyrolytic deposition of nanostructured titanium carbide coatings on the surface of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kremlev, K. V.; Ob"edkov, A. M.; Ketkov, S. Yu.; Kaverin, B. S.; Semenov, N. M.; Gusev, S. A.; Tatarskii, D. A.; Yunin, P. A.

    2016-05-01

    Nanostructured titanium carbide coatings have been deposited on the surface of multiwalled carbon nanotubes (MWCNTs) by the MOCVD method with bis(cyclopentadienyl)titanium dichloride precursor. The obtained TiC/MWCNT hybrid materials were characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. It is established that a TiC coating deposits onto the MWCNT surface with the formation of a core-shell (MWSNT-TiC) type structure.

  10. Stack growth of aligned multiwalled carbon nanotubes using floating catalyst chemical vapor deposition technique

    NASA Astrophysics Data System (ADS)

    Saheed, Mohamed Shuaib Mohamed; Mohamed, Norani Muti

    2015-04-01

    The Letter reports another approach to grow vertically aligned millimeter length multiwalled carbon nanotubes (MWCNT) using chemical vapor deposition technique. In this stack growth, the first grown MWCNT layer is observe to have been lift-off from the substrate surface by the newly grown underneath layer as a result of the diffusion of iron catalyst and carbon source through the first layer. The first grown layer acts as a permeable membrane allowing the catalyst vapor and carbon to reach the bottom layer and the top surface of the substrate, resulting in the growth of another layer of MWCNT underneath it.

  11. Multiwalled carbon nanotubes as masks against carbon and argon irradiation. A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Denton, Cristian D.; Moreno-Marín, Juan Carlos; Heredia-Avalos, Santiago

    2016-04-01

    Experiments showed that multiwalled carbon nanotubes (MWCNT) can be used as masks against irradiation to create metallic nanowires in a substrate. In order to understand the limitations of this application, it is interesting to know the energy and number of carbon atoms emerging from the MWCNT after the irradiation and how the structure of the MWCNT is modified. Using a molecular dynamics code that we have previously developed, we have simulated the continuous irradiation of MWCNT with carbon and argon projectiles. We have obtained that the use of carbon instead of argon to irradiate the MWCNT increases de effectiveness of the MWCNTs as masks, due to the ability of the carbon projectiles to be part of the MWCNT structure and partially mend the damage produced during irradiation. We have analyzed the number, energy, and spatial distribution of the recoils generated during irradiation and the change of the MWCNT structure as a function of the incident energy (100 and 500 eV), fluence (up to 4.5 ·1015ions /cm2), and number of shells (up to 5-shells) of the MWCNT. These results determine the effectiveness of MWCNT as a mask, being useful to understand whether the atoms emerging from the MWCNT produce damage in the substrate or not. We find that for carbon projectiles the efficiency of MWCNT as masks does not depend much on the fluence, but on the number of nanotube shells and projectile incident energy. On the other hand, for a given nanotube and fluence, we observe a threshold incident energy below which the nanotube acts as a perfect mask.

  12. Ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotube mixtures

    SciTech Connect

    Kozulin, Alexander A. Vorozhtsov, Sergey A. Kulkov, Sergey S.; Kulkov, Sergey N.; Teipel, U.

    2015-10-27

    Comprehensive investigations of aluminum nanopowders, multi-walled carbon nanotubes, and aluminum mixtures with multi-walled carbon nanotubes subjected to ultrasonic deagglomeration in a liquid medium were performed, using microstructural, X-ray diffraction, thermogravimetric, and calorimetric analyses, and specific surface area measurements. The regime of ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotubes in a liquid medium is described, during which the division of large agglomerates and creation of homogeneous distribution of mixtures components in the volume takes place. It was determined that ultrasonic treatment influences the morphology and crystalline structure of investigated mixtures, contributes to the appearance of X-ray amorphous phase, decreases the specific surface area of the aluminum nanopowder from 13 to 12 m{sup 2}/g, and increases the pore volume and average size from 0.04 to 0.06 cm{sup 3}/g and from 12 to 19 nm, respectively. The size of coherently-diffracting domain was determined by the X-ray diffraction analysis is close to that estimated from the specific surface area and corresponds to average crystallites size in the materials under study.

  13. Processing route to disentangle multi-walled carbon nanotube towards ceramic composite.

    PubMed

    Belmonte, M; Vallés, C; Maser, W K; Benito, A M; Martinez, M T; Miranzo, P; Osendi, M I

    2009-10-01

    Multi-walled carbon nanotubes were highly aggregated into ropes after their synthesis by chemical vapour deposition and, therefore, two different methods for disentangling the bundles of nanotubes were studied. One method compared the use of mild and vigorous mechanical treatments in ethanol and the other one employed dispersants in aqueous media. For comparison purposes and according to their different exfoliating behaviour, sodium dodecyl sulphate and gum arabic were selected as dispersants. The results evidenced that mechanical sonication was insufficient for disentangling the ropes, whereas, the combined action of mild sonication in an ultrasonic bath with the addition of gum arabic to an aqueous suspension containing nanotubes improved the exfoliating performance. Stable suspensions of unbundled multi-walled carbon nanotubes were obtained adding only 0.05 wt% of gum arabic with a dispersant/MWNTs concentration ratio of 0.25. These values corresponded to a reduction in the dispersant concentration between 1 to 2 orders of magnitude compared to those commonly employed. In addition, a processing route for manufacturing dense and homogenous silicon nitride composites using spark plasma sintering with 1.8 vol% of multi-walled carbon nanotubes almost free of organics was developed without nanotubes degradation and aggregation. PMID:19908510

  14. Ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotube mixtures

    NASA Astrophysics Data System (ADS)

    Kozulin, Alexander A.; Vorozhtsov, Sergey A.; Kulkov, Sergey S.; Teipel, U.; Kulkov, Sergey N.

    2015-10-01

    Comprehensive investigations of aluminum nanopowders, multi-walled carbon nanotubes, and aluminum mixtures with multi-walled carbon nanotubes subjected to ultrasonic deagglomeration in a liquid medium were performed, using microstructural, X-ray diffraction, thermogravimetric, and calorimetric analyses, and specific surface area measurements. The regime of ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotubes in a liquid medium is described, during which the division of large agglomerates and creation of homogeneous distribution of mixtures components in the volume takes place. It was determined that ultrasonic treatment influences the morphology and crystalline structure of investigated mixtures, contributes to the appearance of X-ray amorphous phase, decreases the specific surface area of the aluminum nanopowder from 13 to 12 m2/g, and increases the pore volume and average size from 0.04 to 0.06 cm3/g and from 12 to 19 nm, respectively. The size of coherently-diffracting domain was determined by the X-ray diffraction analysis is close to that estimated from the specific surface area and corresponds to average crystallites size in the materials under study.

  15. The surface modifications of multi-walled carbon nanotubes for multi-walled carbon nanotube/poly(ether ether ketone) composites

    NASA Astrophysics Data System (ADS)

    Cao, Zongshuang; Qiu, Li; Yang, Yongzhen; Chen, Yongkang; Liu, Xuguang

    2015-10-01

    The effects of surface modifications of multi-walled carbon nanotubes (MWCNTs) on the morphology, dynamic mechanical and tribological properties of multi-walled carbon nanotube/poly(ether ether ketone) (MWCNT/PEEK) composites have been investigated. MWCNTs were treated with mixed acids to obtain acid-functionalized MWCNTs. Then the acid-functionalized MWCNTs were modified with ethanolamine (named e-MWCNTs). The MWCNT/PEEK composites were prepared by a solution-blending method. A more homogeneous distribution of e-MWCNTs within the composites was found with scanning electron microscopy. Dynamic mechanical analysis demonstrated a clear increase in the storage modulus of e-MWCNT/PEEK composites because of the improved interfacial adhesion strength between e-MWCNTs and PEEK. Furthermore, the presence of e-MWCNTs caused an enhancement in the glass transition temperature of the composites. Wear tests have shown that the friction coefficient of e-MWCNT/PEEK composites decreased significantly during the test after the running-in period. This suggests that there is an obvious improvement in tribological properties of e-MWCNT/PEEK composites. Overall, the e-MWCNT/PEEK composites have exhibited improved properties and are promising for their applications in industry.

  16. Synthesis of bamboo-shaped multiwalled carbon nanotubes using thermal chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lee, Cheol Jin; Park, Jung Hoon; Park, Jeunghee

    2000-06-01

    The vertically aligned multiwalled carbon nanotubes (CNT) are synthesized in high density on a large area of cobalt deposited silicon oxide substrate, by thermal chemical vapor deposition using C 2H 2 gas, at 950°C. The diameter of CNTs is distributed in the range of 80-120 nm and the length is about 20 μm. High-resolution transmission electron microscopy analysis reveals that the multiwalled CNTs have the crystalline graphite sheets and the bamboo structure that the tube consists of hollow compartments separated with graphite layers. A possible growth mechanism is suggested to explain the structure of CNTs. The emission current density is 1.1 mA cm -2 at 4.5 V μm -1, showing the Fowler-Nordheim behavior.

  17. Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines.

    PubMed

    Zhao, Junhua; Lu, Lixin; Rabczuk, Timon

    2014-05-28

    Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] and Machado et al. [Phys. Rev. Lett. 110, 105502 (2013)] reported the experimental and molecular dynamics realization of S-like shaped single-walled carbon nanotubes (CNTs), the so-called CNT serpentines. We reported here results from continuum modeling of the binding energy γ between different single- and multi-walled CNT serpentines and substrates as well as the mechanical stability of the CNT serpentine formation. The critical length for the mechanical stability and adhesion of different CNT serpentines are determined in dependence of EiIi, d, and γ, where EiIi and d are the CNT bending stiffness and distance of the CNT translation period. Our continuum model is validated by comparing its solution to full-atom molecular dynamics calculations. The derived analytical solutions are of great importance for understanding the interaction mechanism between different single- and multi-walled CNT serpentines and substrates. PMID:24880308

  18. Improvement of the identification of multiwall carbon nanotubes carpet thermal conductivity by pulsed photothermal method

    SciTech Connect

    Amin-Chalhoub, E.; Wattieaux, G.; Semmar, N.; Gaillard, M.; Petit, A.; Leborgne, C.

    2012-11-01

    Thermal properties in multiwall carbon nanotubes carpets and micro-devices are investigated using a nanosecond photothermal method. Gradually, the identification model and experimental protocol are performed to increase the method accuracy for the thermal conductivity determination. In the experimental protocol, a nanosecond UV monopulse laser beam is used to heat the surface of a multilayer (600 nm of Ti/20 {mu}m of carbon nanotube carpet) sample. In the 1D identification model with two layers and a thermal contact resistance, the effect of the laser excitation temporal shape is taken into account. In this study, this first approach allows to improve the accuracy of apparent thermal conductivity measurements of multiwall carbon nanotubes carpet. The carbon nanotubes carpet apparent thermal conductivity value went from being to 180 {+-} 5 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}. In the second approach, two laser beams are coupled in order to increase the interaction time duration from 27 ns to 60 ns. It becomes possible to probe different depths in the carpet. The obtained value (180 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}) confirms the pulsed photothermal method consistency for porous samples. Finally, assuming that the carbon nanotubes are parallel and without any defects, the equivalent intrinsic thermal conductivity of a single carbon nanotube is estimated to be around 3600 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}.

  19. Covalently linked deoxyribonucleic acid with multi-walled carbon nanotubes: synthesis and characterization.

    PubMed

    Chen, Weiwei; Yi, Changqing; Chi-Hung, Tzang; Lee, Shuit-Tong; Yang, Mengsu

    2010-01-01

    In this chapter, a multi-step protocol for covalently linking functionalized multi-walled carbon nanotubes (MWCNT) to deoxyribonucleic acid (DNA) oligonucleotides is provided. X-ray photoelectron spectroscopy (XPS) is used to characterize the initially formed amine-terminated MWCNTs, to which DNA is covalently anchored. Atomic force microscopy (AFM) investigation of the DNA-MWCNT conjugates reveals that the chemical functionalization occurs at both the ends and sidewalls of the nanotubes. The described methodology represents an important step toward the realization of DNA-guided self-assembly for carbon nanotubes. PMID:20422378

  20. The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

    NASA Astrophysics Data System (ADS)

    Burmistrov, I. N.; Muratov, D. S.; Ilinykh, I. A.; Kolesnikov, E. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

  1. Raman, EELS and XPS studies of maghemite decorated multi-walled carbon nanotubes.

    PubMed

    Zhang, Wei; Stolojan, Vlad; Silva, S Ravi P; Wu, Cheng Wei

    2014-01-01

    Iron oxide particles with the diameter being 5-10 nm were attached onto the sidewalls of multi-walled carbon nanotubes (MWCNTs) by the thermal decomposition of cyclopentadieny iron (II) dicarbonyl dimmer. The red shift of G-mode from 1579 cm(-1) to 1571 cm(-1) in the Raman profile of the decorated MWCNTs is indicative of the attachment of nanoparticles. Electron energy loss spectroscopy and X-ray photoelectron spectroscopy analyses reveals that the attached nanoparticles are composed of a maghemite phase. Transmission electron microscopy suggests the maghemite particles are covered with amorphous carbon materials and form a core-shell structure. PMID:24374884

  2. Optical and electrical characterizations of nanocomposite film of titania adsorbed onto oxidized multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Feng, Yiyu; Wu, Zigang; Fujii, Akihiko; Ozaki, Masanori; Yoshino, Katsumi

    2005-07-01

    Composite film containing titania electrostatically linked to oxidized multiwalled carbon nanotubes (TiO2-s-MWNTs) was prepared from a suspension of TiO2 nanoparticles in soluble carbon nanotubes. The structure of the film was analysed principally by Fourier transform infrared spectroscopy, scanning electron micrography and x-ray diffraction. The optical and electrical characterizations of the film were investigated by UV-vis spectrum, photoluminescence and photoconductivity. The enhancement of photocurrent in the TiO2-s-MWNT film is discussed by taking the photoinduced charge transfer between the MWNT and TiO2 into consideration.

  3. Methane preconcentration in a microtrap using multiwalled carbon nanotubes as sorbents.

    PubMed

    Saridara, Chutarat; Ragunath, Smruti; Pu, Yong; Mitra, Somenath

    2010-09-10

    The GC monitoring of green house gases is a challenging task because the concentration of organic species such as methane are relatively low (ppm to ppb) and their analysis requires some level of preconcentration. Since methane is highly volatile, it is not easily retained on conventional sorbents. In this paper we present multiwalled carbon nanotubes (MWNTs) as an effective sorbent for a microtrap designed for methane preconcentration. Its performance was compared to other commercially available carbon based sorbents, and it was found to be the most effective sorbent in terms of breakthrough volume and enthalpy of adsorption. PMID:20850589

  4. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyu; Miao, Yun; Ye, Pingping; Wen, Ying; Yang, Haifeng

    2014-04-01

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA-MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species.

  5. Chemical modification of multi-walled carbon nanotubes using a tetrazine derivative

    NASA Astrophysics Data System (ADS)

    Hayden, Hugh; Gun'ko, Yurii K.; Perova, Tatiana S.

    2007-02-01

    Multi-walled carbon nanotubes (MWNTs) have been reacted with 3,6-diaminotetrazine under heating. This process involves series of interactions between tetrazines and carbon nanotubes including π-π interactions, cycloaddition (Diels-Alder) and cross-linking reactions. These interactions resulted in coating of the MWNTs and in the formation of Y-junctions between nanotubes. Long heating (48 h) of MWNTs with the terazine resulted in a partial destruction of nanotubes due to their excessive functionalisation. The new nanocomposites have been studied by TEM, FTIR and Raman spectroscopy.

  6. Parameterizing A Surface Water Model for Multiwalled Carbon Nanotubes

    EPA Science Inventory

    The unique electronic, mechanical, and structural properties of carbon nanotubes (CNTs) has lead to increasing production of these versatile materials; currently, the use of carbon-based nanomaterials in consumer products is second only to that of nano-scale silver. Although ther...

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

    PubMed Central

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

    2015-01-01

    Nitrogen-doped multi-walled carbon nanotubes (ND-MWCNTs) are modified multi-walled carbon nanotubes (MWCNTs) with enhanced electrical properties that are used in a variety of applications, including fuel cells and sensors; however, the mode of toxic action of ND-MWCNT has yet to be fully elucidated. In the present study, we compared the interaction of ND-MWCNT or pristine MWCNT-7 with human small airway epithelial cells (SAEC) and evaluated their subsequent bioactive effects. Transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction suggested the presence of N-containing defects in the lattice of the nanotube. The ND-MWCNTs were determined to be 93.3% carbon, 3.8% oxygen, and 2.9% nitrogen. A dose–response cell proliferation assay showed that low doses of ND-MWCNT (1.2 mg/ml) or MWCNT-7 (0.1 mg/ml) increased cellular proliferation, while the highest dose of 120 mg/ml of either material decreased proliferation. ND-MWCNT and MWCNT-7 appeared to interact with SAEC at 6 h and were internalized by 24 h. ROS were elevated at 6 and 24 h in ND-MWCNT exposed cells, but only at 6 h in MWCNT-7 exposed cells. Significant alterations to the cell cycle were observed in SAEC exposed to either 1.2 mg/ml of ND-MWCNT or MWCNT-7 in a time and material-dependent manner, possibly suggesting potential damage or alterations to cell cycle machinery. Our results indicate that ND-MWCNT induce effects in SAEC over a time and dose-related manner which differ from MWCNT-7. Therefore, the physicochemical characteristics of the materials appear to alter their biological effects. PMID:25797581

  8. Sodium insertion/extraction from single-walled and multi-walled carbon nanotubes: The differences and similarities

    NASA Astrophysics Data System (ADS)

    Goonetilleke, Damian; Pramudita, James C.; Choucair, Mohammad; Rawal, Aditya; Sharma, Neeraj

    2016-05-01

    A comparative study on the sodium-ion insertion and extraction of commercially-available multi-wall and single-wall carbon nanotubes is reported. Single-wall carbon nanotubes exhibit charge/discharge capacities of 126 mA h g-1 and multi-wall carbon nanotubes produce a lower capacity of 28 mA h g-1 after 50 cycles at 25 mA g-1. To understand these differences, a combination of X-ray diffraction and solid state nuclear magnetic resonance measurements were performed at various states of sodium insertion and extraction.23Na nuclear magnetic resonance studies, a technique previously rarely used for characterising electrodes from sodium-ion batteries, shows differences in the sodium chemical environment near multi-wall compared to single-wall carbon nanotubes with distinct sodium sites found to be active during sodium insertion and extraction for the carbon nanotubes. Both types of carbon nanotubes show a similar amount of reversible sodium available for insertion/extraction reactions, but multi-wall carbon nanotubes feature half the initial insertion capacity relative to single-wall carbon nanotubes. The electrochemical performance of the carbon nanotube electrodes are discussed in relation to the observed mechanism of sodium insertion.

  9. An evaluation of the impact of multi-walled carbon nanotubes on soil microbial community structure and functional diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing application of carbon nanotubes (CNTs) triggers the need for an assessment of their effects on organisms in the environment. Soil microbial communities play a significant role in soil organic matter dynamics and nutrient cycling. This study evaluated the impacts of multi-walled carbon nan...

  10. Distinct electrical effects of multi-walled carbon nanotubes in two composites

    NASA Astrophysics Data System (ADS)

    Wang, Leizhi; Wang, Hua; Datta, Timir; Yin, Ming; Tian, Xingyou

    2014-11-01

    The temperature dependent conductivity of multi-walled carbon nanotube film (MWNT) is reported and the different electrical properties of nanotubes in two composites are compared. Due to the disordered structures, our carbon nanotube film displays variable range hopping behavior. While the geometric distributions of carbon nanotubes in the conducting polyaniline (PANI) and insulating polyamide (PA66) are similar, charge carriers transport distinctly. The conductive PANI, following one-dimensional variable range hopping, dominates the electrical properties of MWNT/PANI composites. The effect of MWNTs becomes prominent only at low temperature range. However, the contact junctions composed by adjacent carbon nanotubes, instead of nanotubes themselves or the polymer matrix, determine the electrical properties of MWNT/PA66 composites, showing the fluctuation induced tunneling characteristic.

  11. Ferromagnetic behaviour of anthropogenic multi-walled carbon nanotubes trapped in spider web indoor.

    PubMed

    Sonkar, Sumit Kumar; Tripathi, Kumud Malika; Sarkar, Sabyasachi

    2014-03-01

    Black carbon (BC) (as partly burnt black particulate matter) present indoor are deposited on interior surfaces of the indoors (easily visualize over the blades of electric fan/exhausts and over domestic spider webs) are known to be a potential indoor pollution problem. We detect with the help of indoor spider webs the floating BC contains a significant amount of defective multiwalled carbon nanotubes (MWCNTs) possessing room temperature ferromagnetism. Microscopic studies shows a lot of internal and surfacial defects in these indoor-MWCNTs. Electron paramagnetic resonance (EPR) showed the presence of very stable carbon centred radicals in these indoor-MWCNTs. Room temperature ferromagnetism most importantly originated by the presence of a large amount of unpaired spin frustrated carbon centred radicals (trapped in defects, junctions and fractures) which are inadvertently formed during the pyrolysis of carbonaceous materials through routine domestic activities. PMID:24745259

  12. Polarization Losses under Accelerated Stress Test Using Multiwalled Carbon Nanotube Supported Pt Catalyst in PEM Fuel Cells

    SciTech Connect

    Park, Seh K.; Shao, Yuyan; Kou, Rong; Viswanathan, Vilayanur V.; Towne, Silas A.; Rieke, Peter C.; Liu, Jun; Lin, Yuehe; Wang, Yong

    2011-03-01

    The electrochemical behavior for Pt catalysts supported on multiwalled carbon nanotubes and Vulcan XC-72 in proton exchange membrane fuel cells under accelerated stress test was examined by cyclic voltammetry, electrochemical impedance spectroscopy, and polarization technique. Pt catalyst supported on multiwalled carbon nanotubes exhibited highly stable electrochemical surface area, oxygen reduction kinetics, and fuel cell performance at a highly oxidizing condition, indicating multiwalled carbon nanotubes show high corrosion resistance and strong interaction with Pt nanoparticles. The Tafel slope, ohmic resistances, and limiting current density determined were used to differentiate kinetic, ohmic, mass-transfer polarization losses from the actual polarization curve. Kinetic contribution to the total overpotential was larger throughout the stress test. However, the fraction of kinetic overpotential decreased and mass-transfer overpotential portion remained quite constant during accelerated stress test, whereas the fraction of ohmic overpotential primarily originating from severe proton transport limitation in the catalyst layer increased under the anodic potential hold.

  13. Direct Oxidation of Tryptophan on Multi-Wall Carbon Nanotubes Modified Carbon Electrode and its Application to Fuel Cell

    NASA Astrophysics Data System (ADS)

    Yabutani, Tomoki; Shoda, Yoshio; Tani, Yuji; Yamada, Yohei; Motonaka, Junko

    Direct oxidation of tryptophan on multi-wall carbon nanotubes modified glassy carbon electrode was examined. Surface poisoning, which was suppression of oxidative current caused from adsorption of oxidized compounds of amino acids through multiple redox scan, was observed on carbon material electrodes (multi-wall carbon nano tube(CNT), carbon powder(CP), Ketjen Black (KB) and glassy carbon(GC). It was found that CNT showed a highly inhibitory effect on the surface poisoning and high current value in the direct oxidation of tryptophan because of a π-π interaction between CNT and indole ring of tryptophan results from orbital mixing. This CNT modified GC electrode was applied to an anode in a fuel cell used with amino acids as fuel. As a result, the maximum of the power density showed 0.36 mW cm-2 at 2.5 mA cm-2 of the current density and 140 mV of the cell voltage.

  14. Direct evaluation of ballistic phonon transport in a multi-walled carbon nanotube

    SciTech Connect

    Hayashi, Hiroyuki; Takahashi, Koji; Ikuta, Tatsuya; Nishiyama, Takashi; Takata, Yasuyuki; Zhang, Xing

    2014-03-17

    Phonon confinement and in situ thermal conductance measurements in an individual multi-walled carbon nanotube (MWNT) are reported. Focused ion beam (FIB) irradiation was used to successively shorten a 4.8 μm long MWNT, eventually yielding a 0.3 μm long MWNT. After the first FIB irradiation, a 41% reduction in conductance was achieved, compared with that of the pristine MWNT. This was because the contributions from phonons with long free paths were excluded by scattering at FIB-induced defects. Phonon transport in linked multiple-length nanotubes was also investigated.

  15. Thermal properties of multi-walled carbon nanotubes-graphite nanosheets/epoxy nanocomposites

    NASA Astrophysics Data System (ADS)

    Ramana, G. Venkata; Padya, Balaji; Srikanth, Vadali V. S. S.; Jain, P. K.

    2013-06-01

    Multi-walled carbon nanotubes (MWCNTs) and graphite nanosheets (GNS) reinforced epoxy nanocomposites are synthesized by solution mixing process. Various surface active groups on filler materials are analyzed and their effect on dispersion, interfacial bonding was correlated to the thermal conductivity and dimensional stability of the nanocomposites. Thermal conductivity of MWCNTs/epoxy nanocomposites was enhanced by 34% when compared to GNS/epoxy nanocomposites at room temperature. Improved dimensional stability was also observed in the case of MWCNTs/epoxy nanocomposites. Poor thermal properties of GNS/epoxy nanocomposites are due to formation of GNS agglomerates in the nanocomposites.

  16. Biofunctionalization of multiwalled carbon nanotubes by electropolymerized poly(pyrrole-concanavalin A) films.

    PubMed

    Papper, Vladislav; Elouarzaki, Kamal; Gorgy, Karine; Sukharaharja, Ayrine; Cosnier, Serge; Marks, Robert S

    2014-10-13

    The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) . PMID:25179428

  17. Synthesis of Ru/multiwalled carbon nanotubes by microemulsion for electrochemical supercapacitor

    SciTech Connect

    Yan Shancheng; Qu Peng; Wang Haitao; Tian Tian; Xiao Zhongdang

    2008-10-02

    An efficient way to decorate multiwalled carbon nanotubes with Ru had been developed. In this method, Ru nanoparticles were prepared by water-in-oil reverse microemulsion, and the produced Ru anchored on MWCNTs. Transmission electron microscopy (TEM) result showed that RuO{sub 2} nanoparticles had the uniform size distribution after electrochemical oxidation. Energy dispersive X-rays (EDX) spectra elucidated the presence of ruthenium oxide in the as-prepared composites after electrochemical oxidation. Cyclic voltammetry result demonstrated that a specific capacitance of deposited ruthenium oxide electrode was significantly greater than that of the pristine MWCNTs electrode in the same medium.

  18. Nematic liquid crystal reorientation around multi-walled carbon nanotubes mapped via Raman microscopy.

    PubMed

    Cacace, T; García-García, A; Zito, G; Tkachenko, V; Rusciano, G; Geday, M A; Otón, J M; Marino, A; Sasso, A

    2016-07-11

    We have studied the formation of topological defects in liquid crystal (LC) matrices induced by multiwalled carbon nanotubes (MWCNTs) and external electric fields. The defects are ascribable to a distortion of the LC molecular director in proximity of the MWCNT surface. The system is analyzed macroscopically using spectroscopic variable angle ellipsometry. Concurrently, confocal micro-Raman spectroscopy is used to study the system state at the microscale. This allows to acquire a three-dimensional, spatially-resolved map of the topological defect, determining scale length variations and orientation topography of the LC molecules around the MWCNT. PMID:27410863

  19. New synthesis and physical property of low resistivity boron-doped multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ishii, S.; Watanabe, T.; Ueda, S.; Tsuda, S.; Yamaguchi, T.; Takano, Y.

    2008-09-01

    A novel growth technique of boron-doped multi-walled carbon nanotubes (MWNTs) was developed. Our new technique uses a methanol solution of boric acid as a source material. Resistivity of the boron-doped MWNTs was successfully reduced independently of chirality by our technique. Temperature dependence of resistivity in each individual boron-doped MWNT was measured by using small-sized four-point contacts, which were fabricated by electron beam (EB) lithography technique. Conduction carriers were introduced into the MWNT effectively by boron-doping.

  20. Broad-frequency dielectric behaviors in multiwalled carbon nanotube/rubber nanocomposites

    NASA Astrophysics Data System (ADS)

    Jiang, Mei-Juan; Dang, Zhi-Min; Bozlar, Michael; Miomandre, Fabien; Bai, Jinbo

    2009-10-01

    Broad-frequency dielectric behaviors of multiwalled carbon nanotubes (MWCNTs) embedded in room temperature vulcanization silicone rubber (RT-SR) matrix were studied by analyzing alternating current (ac) impedance spectra, which would make a remarkable contribution for understanding some fundamental electrical properties in the MWCNT/RT-SR nanocomposites. Equivalent circuits of the MWCNT/RT-SR nanocomposites were built, and the law of polarization and mechanism of electric conductance under the ac field were acquired. Two parallel RC circuits in series are the equivalent circuits of the MWCNT/RT-SR composites. At different frequency ranges, dielectric parameters including conductivity, dielectric permittivity, dielectric loss, impedance phase, and magnitude present different behaviors.

  1. UV photovoltaic cells based on conjugated ZnO quantum dot/multiwalled carbon nanotube heterostructures

    NASA Astrophysics Data System (ADS)

    Li, Fushan; Cho, Sung Hwan; Son, Dong Ick; Kim, Tae Whan; Lee, Sun-Kyun; Cho, Yong-Hoon; Jin, Sungho

    2009-03-01

    In situ growth of ZnO quantum dots (QDs) on the surface of multiwalled carbon nanotubes (MWCNTs) was realized via a mild solution-process method, which resulted in an improvement in photoinduced charge separation and transport of carriers to the collecting electrode. The charge transfer efficiency was significantly increased by more than 90% due to the conjugation of ZnO QDs with MWCNTs, as confirmed by photoluminescence measurements. Ultraviolet photovoltaic cells based on the charge transfer at the ZnO QD-MWCNT heterostructures were fabricated, and their power conversion efficiency was measured to be above 1%.

  2. Multiband microwave absorption films based on defective multiwalled carbon nanotubes added carbonyl iron/acrylic resin

    NASA Astrophysics Data System (ADS)

    Li, Yong; Chen, Changxin; Pan, Xiaoyan; Ni, Yuwei; Zhang, Song; Huang, Jie; Chen, Da; Zhang, Yafei

    2009-05-01

    Defective multiwalled carbon nanotubes (MWCNTs) were introduced to the carbonyl iron (CI) based composites to improve its microwave absorption by a simple ultrasonic mixing process. The electromagnetic parameters were measured in the 2-18 GHz range. Microwave absorption of CI based composites with 2 mm in thickness was evidently enhanced by adding as little as 1.0 wt% defective MWCNTs with two well separated absorption peaks exceeding -20 dB, as compared with that of pure CI based and defective MWCNTs composites. The enhancement mechanism is thought due to the interaction and better electromagnetic match between defective MWCNTs and ferromagnetic CI particles.

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

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

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

  4. Ultrasonic-assisted chemical oxidative cutting of multiwalled carbon nanotubes with ammonium persulfate in neutral media

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Wang, Tingmei

    2009-12-01

    A new, facile, and mild approach was developed to cut the conventional long and entangled multiwalled carbon nanotubes (MWCNTs) to short and dispersed ones with length of less than 1 μm by ultrasonic-assisted chemical oxidation with ammonium persulfate (APS) in neutral aqueous solution at room temperature. The resulting products were characterized with Fourier transform infrared (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and transmission electron microscope (TEM) techniques. The shortened MWCNTs formed stable dispersion state in water without the help of surfactants that provided possibility for further functionalizations and applications.

  5. Effect of Multiwall Carbon Nanotubes on Electrical and Structural Properties of Polyaniline

    NASA Astrophysics Data System (ADS)

    Nagaraja, M.; Mahesh, H. M.; Manjanna, J.; Rajanna, K.; Kurian, M. Z.; Lokesh, S. V.

    2012-07-01

    Polyaniline (PANI) and PANI/CNT (multiwall carbon nanotubes, CNT) composites were prepared using an oxidative chemical polymerization method with ammonium persulfate and dodecyl benzene sulfonic acid as the oxidizing agent and surfactant, respectively. Fourier-transform infrared spectroscopy spectra illustrate the presence of PANI in the composite and show that some interaction exists between PANI and CNT. Embedding of CNT in the PANI matrix is confirmed by scanning electron micrography. Conductivity of the PANI/CNT composites was higher than that of pure PANI, and the maximum conductivity obtained was 4.44 S/cm at 20 wt.% CNT.

  6. Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds.

    PubMed

    Lobo, Anderson O; Antunes, Erica F; Palma, Mariana Bs; Pacheco-Soares, Cristina; Trava-Airoldi, Vladimir J; Corat, Evaldo J

    2010-04-01

    Monolayer formation of SaOS-2 (human osteoblast-like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non-toxicity and the flat spreading with monolayer formation of the SaOs-2 on VACNT scaffolds surface indicate that they can be used for biomedical applications. PMID:19947917

  7. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    SciTech Connect

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  8. Multiwalled carbon nanotubes for dielectric sensing of biological systems: An effective treatment of polarization

    NASA Astrophysics Data System (ADS)

    Picaud, F.; Girardet, C.

    We determine the efficiency of semi-conducting multiwalled carbon nanotubes in resonator configuration acting as sensors of biological systems. The resonance frequency shifts due to the dielectric changes of the resonator upon adsorption of highly idealized micelles schematized by a set of concentric shells of polarizable centers surrounded by a water shell to mimic the solvent are calculated on the basis of an effective polarizability distribution in the tube and the sensed system. Cylindrical and spherical geometries including different sizes are considered for the micelles to show that size and geometry selectivity could be reached with such an approach.

  9. Fabrication of multi-walled carbon nanotubes-aluminum matrix composite by powder metallurgy technique

    NASA Astrophysics Data System (ADS)

    Bunakov, N. A.; Kozlov, D. V.; Golovanov, V. N.; Klimov, E. S.; Grebchuk, E. E.; Efimov, M. S.; Kostishko, B. B.

    We report on fabrication of an aluminum matrix composite containing multi-walled carbon nanotubes (MWCNTs) produced by MOCVD method and functionalized via acid treatment by a H2SO4/HNO3 mixture. Specimens were prepared by spark plasma sintering (SPS) of the aluminum powder with different amounts of functionalized MWCNTs (FMWCNTs) in the range of 0.1-1 wt.%. We studied the effect of FMWCNTs amount on microstructure and mechanical properties of composites. It is shown that functionalization allows homogeneous dispersing of the MWCNTs in Al powder. The maximal increase in micro-hardness and tensile strength is registered at 0.1 wt.%.

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

    SciTech Connect

    Mitrani, J. M.; Shneider, M. N.

    2015-01-26

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

  11. Multiwalled carbon nanotubes sensor for organic liquid detection at room temperature

    NASA Astrophysics Data System (ADS)

    Chaudhary, Deepti; Khare, Neeraj; Vankar, V. D.

    2016-04-01

    We have explored the possibility of using multiwalled carbon nanotubes (MWCNTs) as room temperature chemical sensor for the detection of organic liquids such as ethanol, propanol, methanol and toluene. MWCNTs were synthesized by thermal chemical vapor deposition (TCVD) technique. The interdigitated electrodes were fabricated by conventional photolithography technique. The sensor was fabricated by drop depositing MWCNT suspension onto the interdigitated electrodes. The sensing properties of MWCNTs sensor was studied for organic liquids detection. The resistance of sensor was found to increase upon exposure to these liquids. Sensor shows good reversibility and fast response at room temperature. Charge transfer between the organic liquid and sensing element is the dominant sensing mechanism.

  12. Flexible infrared detectors based on p-n junctions of multi-walled carbon nanotubes.

    PubMed

    Huang, Zhenlong; Gao, Min; Yan, Zhuocheng; Pan, Taisong; Liao, Feiyi; Lin, Yuan

    2016-05-14

    Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm(-2) even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors. PMID:27101973

  13. Application of multiwalled carbon nanotubes-graphene hybrid nanocomposite for nonenzymatic H2O2 biosensor

    NASA Astrophysics Data System (ADS)

    Nayak, Pranati; Santhosh, P. N.; Ramaprabhu, S.

    2013-02-01

    In the present work, we report the fabrication of nonenzymatic hydrogen peroxide (H2O2) biosensor using multiwalled carbon nanotubes-solar exfoliated graphene hybrid nanocomposite (MWCNTs-sG) as a transducer candidate. The hybrid material has been synthesized by solar reduction technique from a mixture of MWCNTs and graphite oxide (GO). The fabricated MWCNTs-sG based biosensor shows a high catalytic response towards H2O2 reduction at a low potential of -0.4 V and good linearity over a wide range of concentration from 2 mM to 344 mM.

  14. Decorating multi-walled carbon nanotubes with nickel nanoparticles for selective hydrogenation of citral

    SciTech Connect

    Tang Yuechao; Yang Dong; Qin Feng; Hu Jianhua; Wang Changchun; Xu Hualong

    2009-08-15

    The nanocomposites of multi-walled carbon nanotubes (MWNTs) decorated with nickel nanoparticles were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). Due to the strong interaction between Ni{sup 2+} and -COOH, PAA-g-MWNTs became an excellent supporting material for Ni nanoparticles. The morphology and distribution of Ni nanoparticles on the surface of MWNTs were greatly influenced by the reduction temperatures, the experimental results also showed that the distribution of Ni nanoparticles was greatly improved while the MWNTs were modified by poly(acrylic acid) (PAA). The hydrogenation activity and selectivity of MWNTs decorated with Ni nanoparticles (Ni-MWNTs) for alpha, beta-unsaturated aldehyde (citral) were also studied, and the experimental results showed that the citronellal, an important raw material for flavoring and perfumery industries, is the favorable product with a percentage as high as 86.9%, which is 7 times higher than that of catalyst by Ni-supported active carbon (Ni-AC). - Abstract: Nickel nanoparticles decorated multi-walled carbon nanotubes (Ni-MWNTs) nanocomposites were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). These nanocomposites possessed excellent catalytic activity and selectivity for hydrogenation of citral.

  15. Controlled Patterning and Growth of Single Wall and Multi-wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor)

    2005-01-01

    Method and system for producing a selected pattern or array of at least one of a single wall nanotube and/or a multi-wall nanotube containing primarily carbon. A substrate is coated with a first layer (optional) of a first selected metal (e.g., Al and/or Ir) and with a second layer of a catalyst (e.g., Fe, Co, Ni and/or Mo), having selected first and second layer thicknesses provided by ion sputtering, arc discharge, laser ablation, evaporation or CVD. The first layer and/or the second layer may be formed in a desired non-uniform pattern, using a mask with suitable aperture(s), to promote growth of carbon nanotubes in a corresponding pattern. A selected heated feed gas (primarily CH4 or C2Hn with n=2 and/or 4) is passed over the coated substrate and forms primarily single wall nanotubes or multiple wall nanotubes, depending upon the selected feed gas and its temperature. Nanofibers, as well as single wall and multi-wall nanotubes, are produced using plasma-aided growth from the second (catalyst) layer. An overcoating of a selected metal or alloy can be deposited, over the second layer, to provide a coating for the carbon nanotubes grown in this manner.

  16. Strain and Temperature Sensing Properties of Multiwalled Carbon Nanotube Yarn Composites

    NASA Technical Reports Server (NTRS)

    Kahng, Seun K.; Gates, Thomas S.; Jefferson, Gail D.

    2008-01-01

    Strain and temperature response of Multiwalled Carbon Nanotube (MWCNT/CNT) yarns on a stainless steel test beam has been studied. The carbon nanotube yarns are spun from a multiwalled carbon nanotube forest grown on a silicon substrate to a 4-ply yarn with a diameter of about 15-20 microns. Four of the 4-ply CNT yarns are arranged in a Wheatstone bridge configuration on the stainless steel test beam using a thin layer of polyurethane resin that insulates and protects the yarns from the test beam. Strain sensitivities of the CNT yarn sensors range from 1.39 to 1.75 mV/V/1000 microstrain at room temperature, and temperature sensitivity of the CNT yarn bridge is 91 microA/degC. Resistance of the yarns range from 215 to 270 ohms for CNT yarn length of approximately 5 mm. Processes used in attaching the CNT yarns on the test beam and experimental procedures used for the measurements are described. Conventional metallic foil strain gages are attached to the test beam to compare with the CNT sensors. The study demonstrates multifunctional capability of the sensor for strain and temperature measurements and shows its applicability where engineering strain is less than 3%.

  17. Facile Synthesis of Highly Aligned Multiwalled Carbon Nanotubes from Polymer Precursors

    DOE PAGESBeta

    Han, Catherine Y.; Xiao, Zhi-Li; Wang, H. Hau; Lin, Xiao-Min; Trasobares, Susana; Cook, Russell E.

    2009-01-01

    We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO) membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbonmore » nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.« less

  18. Controllable purification, cutting and unzipping of multi-walled carbon nanotubes with a microwave method

    NASA Astrophysics Data System (ADS)

    Pelalak, R.; Baniadam, M.; Maghrebi, M.

    2013-06-01

    A rapid microwave-assisted method was developed for the purification, cutting and unzipping of arrays of multi-walled carbon nanotubes (MWCNTs) using a mixture of KMnO4 and H2SO4. To harness the extent of treatment, MWCNT products were fully characterized at different reaction times by UV-visible and Raman spectroscopies as well as scanning and transmission electron microscopies. The results show that the carbon nanoparticles and the amorphous carbon which coated the MWCNTs were removed after about 10 minutes. The excessive oxidation of MWCNTs then leads to cutting and unzipping of graphitic walls. Moreover, while the catalyst residues outside the MWCNTs were rapidly extracted up to 10 minutes, the removal of catalyst residues inside the MWCNTs did not begin before 20 minutes. This method can be considered as an efficient route for the purification, cutting and unzipping of MWCNTs due to its fast and controllable procedure.

  19. Visible and near-infrared radiative properties of vertically aligned multi-walled carbon nanotubes.

    PubMed

    Wang, X J; Flicker, J D; Lee, B J; Ready, W J; Zhang, Z M

    2009-05-27

    This work investigates the reflection and scattering from vertically aligned carbon nanotubes, fabricated on silicon substrate using thermally enhanced chemical vapor deposition with both tip-growth and base-growth mechanisms. The directional-hemispherical reflectance in the visible and near-infrared wavelengths was measured with an integrating sphere. The polarization-dependent bidirectional reflectance distribution function was characterized with a laser scatterometer at the wavelength of 635 nm. The effective medium theory was used to elucidate the mechanism of high absorptance (greater than 0.97 in the spectral region from 400 to 1800 nm) of the multi-walled carbon nanotube samples. It is observed that scattering by impurities on the top of the nanotubes, by the nanotube tips, and by defects and misalignment can significantly increase the reflectance and introduce retroreflection. This study may facilitate application of carbon nanotubes in pyroelectric detectors as well as thermophotovoltaic emitters and absorbers. PMID:19423943

  20. Tunneling phenomena in aligned multi-walled carbon nanotube sheets: conductivity and Raman correlations

    NASA Astrophysics Data System (ADS)

    del Corro, E.; Castillo-Martínez, E.; Taravillo, M.; Baonza, V. G.

    2014-12-01

    We performed simultaneous Raman spectroscopy and electrical conductivity measurements on self-standing aligned multi-walled carbon nanotubes sheets at varying inter-tube distances. A sapphire anvil cell is used here to modulate the inter-tube distance and promote the subsequent electronic tunneling phenomena. We observe a singular correlation between the intensity of the so called defect bands of carbon materials and their conductivity. This indicates that the conditions of the resonant processes that originate these bands are modified by the tunneling phenomena. Such an issue has never been reported before and has potential technological applications. Additionally, the provided AFM images evidence the debundling of the carbon nanotubes that had been described to occur after small compression.

  1. A novel silica-coated multiwall carbon nanotube with CdTe quantum dots nanocomposite

    NASA Astrophysics Data System (ADS)

    Fei, Qiang; Xiao, Dehai; Zhang, Zhiquan; Huan, Yanfu; Feng, Guodong

    2009-10-01

    A novel silica-coated multiwall carbon nanotube (MWNTs) with CdTe quantum dots nanocomposite was synthesized in this paper. Here, we show the in situ growth of crystalline CdTe quantum dots on the surfaces of oxidized MWNTs. The approach proposed herein differs from previous attempts to synthesize nanotube assemblies in that we mix the oxidized MWNTs into CdCl 2 solution of CdTe nanocrystals synthesized in aqueous solution. Reinforced the QD-MWNTs heterostructures with silica coating, this method is not invasive and does not introduce defects to the structure of carbon nanotubes (CNTs), and it ensures high stability in a range of organic solvents. Furthermore, a narrow SiO 2 layer on the MWNT-CdTe heterostructures can eliminate the biological toxicity of quantum dots and carbon nanotubes. This is not only a breakthrough in the synthesis of one-dimensional nanostructures, but also taking new elements into bio-nanotechnology.

  2. Dielectric constants of multiwall carbon nanotubes from direct current to microwave frequencies.

    PubMed

    Wang, Y C; Lue, J T; Pauw, K F

    2009-03-01

    A cylindrical rod constructed from a uniform mixture of multiwall carbon nanotubes and alumina powders dissolved in paraffin was inserted in the center of a radio frequency cavity. The real and imaginary dielectric constants of carbon tubes at various frequencies were measured, respectively, from the resonant frequencies and the quality factors, by a resistance-inductance-cacitance (RLC) meter and a microwave network analyzer. The dielectric rod benefits the protection of the sample from adsorbing moisture and preventing the rod from filling with air, thus making accurate measurments. A tunable probe specifically designed for the field pattern of a TM010 mode is delineated to improve the microwave coupling of the dielectric microwave resonator. This refined design is expected to facilitate the measurement yielding a significant manner. The real and imaginary parts of the dielectric constant of carbon nanotubes increase and decrease, respectively as frequencies increase satisfactorily in complying with the description from the free electron Drude model. PMID:19435033

  3. Comparative inhalation toxicity of multi-wall carbon nanotubes, graphene, graphite nanoplatelets and low surface carbon black

    PubMed Central

    2013-01-01

    Background Carbon nanotubes, graphene, graphite nanoplatelets and carbon black are seemingly chemically identical carbon-based nano-materials with broad technological applications. Carbon nanotubes and carbon black possess different inhalation toxicities, whereas little is known about graphene and graphite nanoplatelets. Methods In order to compare the inhalation toxicity of the mentioned carbon-based nanomaterials, male Wistar rats were exposed head-nose to atmospheres of the respective materials for 6 hours per day on 5 consecutive days. Target concentrations were 0.1, 0.5, or 2.5 mg/m3 for multi-wall carbon nanotubes and 0.5, 2.5, or 10 mg/m3 for graphene, graphite nanoplatelets and low-surface carbon black. Toxicity was determined after end of exposure and after three-week recovery using broncho-alveolar lavage fluid and microscopic examinations of the entire respiratory tract. Results No adverse effects were observed after inhalation exposure to 10 mg/m3 graphite nanoplatelets or relatively low specific surface area carbon black. Increases of lavage markers indicative for inflammatory processes started at exposure concentration of 0.5 mg/m3 for multi-wall carbon nanotubes and 10 mg/m3 for graphene. Consistent with the changes in lavage fluid, microgranulomas were observed at 2.5 mg/m3 multi-wall carbon nanotubes and 10 mg/m3 graphene. In order to evaluate volumetric loading of the lung as the key parameter driving the toxicity, deposited particle volume was calculated, taking into account different methods to determine the agglomerate density. However, the calculated volumetric load did not correlate to the toxicity, nor did the particle surface burden of the lung. Conclusions The inhalation toxicity of the investigated carbon-based materials is likely to be a complex interaction of several parameters. Until the properties which govern the toxicity are identified, testing by short-term inhalation is the best option to identify hazardous properties in

  4. Atomic-Scale Investigations of Multiwall Carbon Nanotube Growth

    NASA Astrophysics Data System (ADS)

    Behr, Michael John

    The combination of unique mechanical, thermal, optical, and electronic properties of carbon nanotubes (CNTs) make them a desirable material for use in a wide range of applications. Many of these unique properties are highly sensitive to how carbon atoms are arranged within the graphene nanotube wall. Precise structural control of this arrangement remains the key challenge of CNT growth to realizing their technological potential. Plasma-enhanced chemical vapor deposition (PECVD) from methane-hydrogen gas mixtures using catalytic nanoparticles enables large-scale growth of CNT films and controlled spatial placement of CNTs on a substrate, however, much is still unknown about what happens to the catalyst particle during growth, the atomistic mechanisms involved, and how these dictate the final nanotube structure. To investigate the fundamental processes of CNT growth by PECVD, a suite of characterization techniques were implemented, including attenuated total-reflection Fourier transform infrared spectroscopy (ATR-FTIR), optical emission spectroscopy (OES), Raman spectroscopy, convergent-beam electron diffraction (CBED), high-resolution transmission and scanning-transmission electron microscopy (TEM, STEM), energy dispersive x-ray spectroscopy, and electron energy-loss spectroscopy (EELS). It is found that hydrogen plays a critical role in determining the final CNT structure through controlling catalyst crystal phase and morphology. At low hydrogen concentrations in the plasma iron catalysts are converted to Fe3C, from which high-quality CNTs grow; however, catalyst particles remain as pure iron when hydrogen is in abundance, and produce highly defective CNTs with large diameters. The initially faceted and equiaxed catalyst nanocrystals become deformed and are elongated into a teardrop morphology once a tubular CNT structure is formed around the catalyst particles. Although catalyst particles are single crystalline, they exhibit combinations of small-angle (˜1°-3

  5. The Influence of Multiwalled Carbon Nanotubes on Polycyclic Aromatic Hydrocarbon (PAH) Bioavailability and Toxicity to Soil Microbial Communities in Alfalfa Rhizosphere

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carbon nanotubes (CNTs) may affect bioavailability and toxicity of organic contaminants due to their adsorption properties. Recent studies have observed the influence of multiwalled carbon nanotubes (MWNTs) on the fate of polycyclic aromatic hydrocarbons (PAHs) and other organic contaminants. Greenh...

  6. Selective decoration of nickel and nickel oxide nanocrystals on multiwalled carbon nanotubes

    SciTech Connect

    Martis, P.; Venugopal, B.R.; Delhalle, J.; Mekhalif, Z.

    2011-05-15

    A simple route to selective decoration of nickel and nickel oxide nanocrystals on multiwalled carbon nanotubes (MWCNTs) using nickel acetylacetonate (NAA) was successfully achieved for the first time. The homogeneously decorated nanocrystals on MWCNTs were investigated for their structure and morphology by various techniques, such as powder X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, field emission scanning electron microscopy and thermogravimetric analysis. It was found that the size distributions of the nanocrystals on MWCNTs ranged from 8 to 15 nm and they were well resolved. The precursor, NAA, was effectively employed to impregnate the MWCNTs, which on calcination at suitable temperatures and in the presence of hydrogen and nitrogen atmosphere gave rise to nickel and nickel oxide nanocrystals, respectively. -- Graphical abstract: Nickel and nickel oxide nanocrystals were selectively and homogeneously decorated on multiwalled carbon nanotubes using nickel acetylacetonate, as a precursor in a simple and efficient route. Display Omitted Highlights: {yields} A simple route for decoration of nickel and nickel oxide nanocrystals on MWCNTs. {yields} Nickel acetylacetonate used as nickel source for the first time to impregnate on MWCNTs. {yields} Selective decoration was achieved by calcination in hydrogen and nitrogen atmospheres. {yields} The as-decorated nickel and nickel oxide nanocrystals are in the range of 8-15 nm.

  7. Polyamidoamine-grafted multiwalled carbon nanotubes for gene delivery: synthesis, transfection and intracellular trafficking.

    PubMed

    Liu, Min; Chen, Biao; Xue, Yanan; Huang, Jie; Zhang, Liming; Huang, Shiwen; Li, Qingwen; Zhang, Zhijun

    2011-11-16

    Functionalized multiwalled carbon nanotubes (f-MWNTs) are of great interest and designed as a novel gene delivery system. In this paper, we presented synthesis of polyamidoamine-functionalized multiwalled carbon nanotubes (PAA-g-MWNTs) and their application as a novel gene delivery system. The PAA-g-MWNTs, obtained from amide formation between PAA and chemically oxidized MWNTs, were stable in aqueous solution and much less toxic to cells than PAA and PEI 25KDa. More importantly, PAA-g-MWNTs showed comparable or even higher transfection efficiency than PAA and PEI at optimal w/w ratio. Intracellular trafficking of Cy3-labeled pGL-3 indicated that a large number of Cy3-labeled pGL-3 were attached to nucleus membrane, the majority of which was localized in nucleus after incubation with cells for 24 h. We have demonstrated that PAA modification of MWNTs facilitate higher DNA uptake and gene expression in vitro. All these facts suggest potential application of PAA-g-MWNTs as a novel gene vector with high transfection efficiency and low cytotoxicity. PMID:21995530

  8. Flexible infrared detectors based on p-n junctions of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Huang, Zhenlong; Gao, Min; Yan, Zhuocheng; Pan, Taisong; Liao, Feiyi; Lin, Yuan

    2016-05-01

    Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm-2 even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors.Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm-2 even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08791k

  9. Multiwalled carbon nanotube films as small-sized temperature sensors

    NASA Astrophysics Data System (ADS)

    Di Bartolomeo, A.; Sarno, M.; Giubileo, F.; Altavilla, C.; Iemmo, L.; Piano, S.; Bobba, F.; Longobardi, M.; Scarfato, A.; Sannino, D.; Cucolo, A. M.; Ciambelli, P.

    2009-03-01

    We present the fabrication of thick and dense carbon nanotube networks in the form of freestanding films (CNTFs) and the study of their electric resistance as a function of the temperature, from 4 to 420 K. A nonmetallic behavior with a monotonic R(T ) and a temperature coefficient of resistance around -7×10-4 K-1 is generally observed. A behavioral accordance of the CNTF conductance with the temperature measured by a solid-state thermistor (ZnNO, Si, or Pt) is demonstrated, suggesting the possibility of using CNTFs as temperature small-sized (freely scalable) sensors, besides being confirmed by a wide range of sensitivity, fast response, and good stability and durability. Concerning electric behavior, we also underline that a transition from nonmetal to metal slightly below 273 K has been rarely observed. A model involving regions of highly anisotropic metallic conduction separated by tunneling barrier regions can explain the nonmetallic to metallic crossover based on the competing mechanisms of the metallic resistance rise and the barrier resistance lowering.

  10. Multi-walled carbon nanotube-based carbon/carbon composites with three-dimensional network structures

    NASA Astrophysics Data System (ADS)

    Jin, Yuguang; Zhang, Yingying; Zhang, Qiang; Zhang, Rufan; Li, Peng; Qian, Weizhong; Wei, Fei

    2013-06-01

    Multi-walled carbon nanotube (MWCNT)-based carbon/carbon composites were fabricated by the chemical vapor infiltration of pyrolytic carbon into pre-compressed MWCNT blocks. The pyrolytic carbon was deposited on the surface of the MWCNTs and filled the gaps between the MWCNTs, which improved the connection between the MWCNTs and formed a three-dimensional network structure. The mechanical and electrical properties were improved significantly. The values of the maximum compressed deformation, maximum breaking strength, Young's modulus and energy absorption are measured as 10.9%, 148.6 MPa, 1588.6 MPa and 13.8 kJ kg-1, respectively. The conductivity reached about 204.4 S cm-1, more than 10 times larger than that of pre-compressed MWCNT blocks. After annealing at 1800 °C in vacuum, the graphitization improved remarkably. The pyrolytic carbon deposited on the surface of the MWCNTs was rearranged along the walls, and resulted in an increase of the number of walls of the MWCNTs.Multi-walled carbon nanotube (MWCNT)-based carbon/carbon composites were fabricated by the chemical vapor infiltration of pyrolytic carbon into pre-compressed MWCNT blocks. The pyrolytic carbon was deposited on the surface of the MWCNTs and filled the gaps between the MWCNTs, which improved the connection between the MWCNTs and formed a three-dimensional network structure. The mechanical and electrical properties were improved significantly. The values of the maximum compressed deformation, maximum breaking strength, Young's modulus and energy absorption are measured as 10.9%, 148.6 MPa, 1588.6 MPa and 13.8 kJ kg-1, respectively. The conductivity reached about 204.4 S cm-1, more than 10 times larger than that of pre-compressed MWCNT blocks. After annealing at 1800 °C in vacuum, the graphitization improved remarkably. The pyrolytic carbon deposited on the surface of the MWCNTs was rearranged along the walls, and resulted in an increase of the number of walls of the MWCNTs. Electronic supplementary

  11. Carbon dots-decorated multiwalled carbon nanotubes nanocomposites as a high-performance electrochemical sensor for detection of H2O2 in living cells.

    PubMed

    Bai, Jing; Sun, Chunhe; Jiang, Xiue

    2016-07-01

    A novel enzyme-free hydrogen peroxide sensor composed of carbon dots (CDs) and multi-walled carbon nanotubes (MWCNTs) was prepared. It was found that the carbon dots-decorated multi-walled carbon nanotubes nanocomposites (CDs/MWCNTs) modified glassy carbon (GC) electrode (CDs/MWCNTs/GCE) exhibited a significant synergistic electrocatalytic activity towards hydrogen peroxide reduction as compared to carbon dots or multi-walled carbon nanotubes alone, and the CDs/MWCNTs/GCE has shown a low detection limit as well as excellent stability, selectivity, and reproducibility. These remarkable analytical advantages enable the practical application of CDs/MWCNTs/GCE for the real-time tracking of hydrogen peroxide (H2O2) released from human cervical cancer cells with satisfactory results. The enhanced electrochemical activity can be assigned to the edge plane-like defective sites and lattice oxygen in the CDs/MWCNTs nanocomposites due to the small amount of decoration of carbon dots on the multi-walled carbon nanotubes. Based on a facile preparation method and with good electrochemical properties, the CDs/MWCNTs nanocomposites represent a new class of carbon electrode for electrochemical sensor applications. Graphical Abstract CDs/MWCNTs exhibited good electrocatalytic activity and stability to H2O2 reduction and can be used for real-time detection of H2O2 released from living cells. PMID:27108281

  12. Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method

    PubMed Central

    2014-01-01

    For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400°C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Ω/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work. PMID:25232300

  13. Unzipped Nanotube Sheet Films Converted from Spun Multi-Walled Carbon Nanotubes by O2 Plasma.

    PubMed

    Jangr, Hoon-Sik; Jeon, Sang Koo; Shim, Dae Seob; Lee, Nam Hee; Nahm, Seung Hoon

    2015-11-01

    Large-scale graphene or carbon nanotube (CNT) films are good candidates for transparent flexible electrodes, and the strong interest in graphene and CNT films has motivated the scalable production of a good-conductivity and an optically transmitting film. Unzipping techniques for converting CNTs to graphene are especially worthy of notice. Here, we performed nanotube unzipping of the spun multi-walled carbon nanotubes (MWCNTs) to produce networked graphene nanoribbon (GNR) sheet films using an 02 plasma etching method, after which we produced the spun MWCNT film by continually pulling MWCNTs down from the vertical well aligned MWCNTs on the substrate. The electrical resistance was slightly decreased and the optical transmittance was significantly increased when the spun MWCNT films were etched for 20 min by O2 plasma of 100 mA. Plasma etching for the optimized time, which does not change the thickness of the spun MWCNT films, improved the electrical resistance and the optical transmittance. PMID:26726645

  14. Magnetic studies of multi-walled carbon nanotube mats: Ultra-high temperature ferromagnetism or superconductivity?

    NASA Astrophysics Data System (ADS)

    Beeli, Pieder; Zhao, Guo-Meng

    2008-03-01

    We report magnetic measurements up to 1200 K on multi-walled carbon nanotube mats using a Quantum Design vibrating sample magnetometer. Extensive magnetic data consistently show two ferrromagnetic-like transitions at about 1000 K and 1275 K, respectively. The lower transition at about 1000 K is associated with an Fe impurity and its saturation magnetization is in quantitative agreement with the Fe concentration measured from an inductively coupled plasma mass spectrometer. On the other hand, the saturation magnetization for the higher transition phase corresponds to about 0.6% Co impurity concentration, which is about four orders of magnitude larger than that measured from the mass spectrometer. We show that this transition at about 1275 K is not consistent with ferromagnetism of any carbon-based phases or magnetic impurities but with the paramagnetic Meissner effect due to the existence of π Josephson junctions in a granular superconductor.

  15. Ultra-high crystallinity millimeter long multiwall carbon nanotubes fabricated by mechanothermal method

    NASA Astrophysics Data System (ADS)

    Manafi, S. A.; Rahimipour, M. R.; Soltanmoradi, A.

    2012-09-01

    In this work, multi-walled carbon nanotubes (MWCNTs) with ultra-high crystalline structure have been prepared by mechanothermal (MT) method. The novel super nanostructure is introduced for the first time as an extraordinary fullerene-carbon based material which, due to its special electronic and mechanical properties, can be used to construct unique building blocks for nanoengineering. Initially, high ultra-active graphite powder has been obtained by mechanical activation under Ar atmosphere. Finally, the mechanically activated product is heat-treated at 1350 °C for 3-4 h under an Ar gas flow. However, the crystallite size and crystallinity degree of the MWCNTs increased with the increase in annealing temperature.

  16. Chemical splitting of multiwalled carbon nanotubes to enhance electrochemical capacitance for supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Xinlu; Li, Tongtao; Zhang, Xinlin; Zhong, Qineng; Li, Hongyi; Huang, Jiamu

    2014-06-01

    Multiwalled carbon nanotubes (MWCNTs) were chemically split and self-assembled to a flexible porous paper made of graphene oxide nanoribbons (GONRs). The morphology and microstructure of the pristine MWCNTs and GONRs were analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. And the specific surface area and porosity structure were measured by N2 adsorption-desorption. The longitudinally split MWCNTs show an enhancement in specific capacitance from 21 F g-1 to 156 F g-1 compared with the pristine counterpart at 0.1 A g-1 in a 6 M KOH aqueous electrolytes. The electrochemical experiments prove that the chemical splitting of MWCNTs will make inner carbon layers opened and exposed to electrochemical double layers, which can effectively improve the electrochemical capacitance for supercapacitors.

  17. Microstructure and mechanical properties of silicon carbide ceramics reinforced with multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Barmin, A.; Bortnikova, V.; Ivanov, A.; Kornev, V.; Lurie, S.; Solyaev, Y.

    2016-04-01

    A microstructure, a composition and mechanical properties of multi-walled carbon of nanotube-reinforced silicon carbide ceramics were examined. The amount of carbon nanotubes was up to 1% wt. Samples was prepared by spark plasma sintering. It has been found that the optimal sintering temperature is 2000°C with an exposure duration of 5 minutes and a pressure of 50 MPa. The effect of the CNT mass fraction on the Young modulus of silicon carbide ceramics composites was investigated for different temperatures and processing conditions of samples using ultrasonic techniques. It has been established that Young's modulus of ceramics decreases due to addition of CNT. Elastic properties of the composites cross section were characterized using nano-indentation. It has been revealed that the stiffness of the ceramics intergranular phase decreases due to addition of CNT.

  18. Ultraviolet laser treatment of multiwall carbon nanotubes grown at low temperature

    NASA Astrophysics Data System (ADS)

    Kim, J. S.; Ahn, K. S.; Kim, C. O.; Hong, J. P.

    2003-03-01

    Simple laser irradiation of well-aligned multiwall carbon nanotubes (MWCNTs) was performed to intentionally modify structural defects and to ablate possible contamination of the MWCNTs. Scanning electron microscopy and transmission electron microscopy confirmed the clear presence of the MWCNTs with open tips. A Raman spectra exhibited a decrease in an intensity ratio (ID/IG) of 1352 cm-1 (D band) over 1583 cm-1 (G band) peaks by significantly reducing the amorphous carbon phases of D band peaks. The structural improvement in the MWCNTs after optimum laser exposure resulted in a reduction of the turn-on voltage from 1.0 to 0.6 V/μm and an increase in the emission current.

  19. Spatial Frequency Heterodyne Imaging of Water Filled Multi-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Schunk, Francisco; Rand, Danielle; Rose-Petruck, Christoph

    2015-03-01

    Evaporation and condensation of water on multi-walled carbon nanotube (MWCNT) surfaces was monitored as a function of both temperature and time using x-ray Spatial Frequency Heterodyne Imaging (SFHI). SFHI is an imaging method that produces an absorption and scatter image from a single exposure, with increased sensitivity to variations in electron density relative to more common place x-ray imaging techniques. Different features seen in the temporal scatter intensity profiles recorded during evaporation and condensation revealed the existence of an absorption-desorption hysteresis. Effects on the previously mentioned phenomena due to chemical functionalization of the carbon nanotube surfaces were also observed. Functionalization increased the interaction potential between the MWCNT walls and water molecules, altering the evaporation event time scale and increasing the temperature at which condensation could take place. The observed temperature dependent changes in evaporation time scales coincide with the boiling point for confined water predicted by the Kelvin equation.

  20. Synthesis and enhanced photocatalytic activity of tin oxide nanoparticles coated on multi-walled carbon nanotube

    SciTech Connect

    Wang, Ning; Xu, Jiaoxing; Guan, Lunhui

    2011-09-15

    Highlights: {yields} SnO{sub 2} nanoparticles were uniformly deposited on carbon nanotubes. {yields} MWNT@SnO{sub 2} showed excellent photocatalytic activity. {yields} The quenched PL proved the existence of electron transfer between SnO{sub 2} and MWNT. -- Abstract: A nanocomposite of SnO{sub 2} nanoparticles coated on multi-walled carbon nanotube (MWNT@SnO{sub 2}) was synthesized and characterized by thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, nitrogen physisorption measurements, photoluminescence. The results show that the SnO{sub 2} nanoparticles with a narrow size of 4 nm are uniformly deposited on MWNT. The photocatalytic activity of the nanocomposite was studied using methyl orange as a model organic pollutant. MWNT@SnO{sub 2} exhibits much higher photocatalytic activity than that of commercial TiO{sub 2} (P-25). The promotion is mainly contributed from electron transfer between SnO{sub 2} and MWNT.

  1. Production of palladium nanoparticles supported on multiwalled carbon nanotubes by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Rojas, J. V.; Castano, C. H.

    2012-01-01

    Palladium nanoparticles were produced and supported on multiwalled carbon nanotubes (MWCNT) by gamma irradiation. A solution with a specific ratio of 2:1 of water-isopropanol was prepared and mixed with palladium chloride and the surfactant sodium dodecyl sulfate (SDS). The gamma radiolysis of water ultimately produces Pd metallic particles that serve as nucleation seeds. Isopropanol is used as an ion scavenger to balance the reaction, and the coalescence of the metal nanoparticles was controlled by the addition of SDS as a stabilizer. The size and distribution of nanoparticles on the carbon nanotubes (CNT) were studied at different surfactant concentrations and radiation doses. SEM, STEM and XPS were used for morphological, chemical and structural characterization of the nanostructure. Nanoparticles obtained for doses between 10 and 40 kGy, ranged in size 5-30 nm. The smaller nanoparticles were obtained at the higher doses and vice versa. Histograms of particle size distributions at different doses are presented.

  2. Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method

    NASA Astrophysics Data System (ADS)

    Tsai, Wan-Lin; Wang, Kuang-Yu; Chang, Yao-Jen; Li, Yu-Ren; Yang, Po-Yu; Chen, Kuan-Neng; Cheng, Huang-Chung

    2014-08-01

    For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400°C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Ω/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work.

  3. Multi-Walled Carbon Nanotube Functionalization by Radical Addition Using Hydroxymethylene Groups.

    PubMed

    Rodríguez-Jiménez, Rubén; Alonso-Núñez, Gabriel; Paraguay-Delgado, Francisco; Espinoza-Gómez, Heriberto; Vélez-López, Ernesto; Rogel-Hernández, Eduardo

    2016-01-01

    Synthetic methodology and characterization of multi-walled carbon nanotubes (MWCNTs) function- alized with hydroxymethylene groups are reported. The MWCNTs were synthesized by the spray pyrolysis technique using toluene as carbon source and ferrocene as catalyst. Hydroxymethylation of MWCNTs was carried out by methanol using benzoyl peroxide (BPO) at different quantities (300 to 900 mg); the optimum BPO quantity was 300 mg. The resulting materials were characterized by FT-IR, Raman Spectroscopy, Thermal Gravimetric Analysis (TGA) and Transmission Electron Microscopy (TEM). The presence of the hydroxymethylene group on the MWCNTs surface was demonstrated by FT-IR, Raman Spectroscopy, TGA, EDS, TEM and Mass Spectrometry. The func- tionalized MWCNTs were not damaged by this methodology. PMID:27398563

  4. Application of multiwalled carbon nanotubes/ionic liquid modified electrode for amperometric determination of sulfadiazine.

    PubMed

    Hong, Xiaoping; Zhu, Yan; Ma, Jingying

    2012-12-01

    A highly sensitive amperometric sulfadiazine sensor based on coating multiwalled carbon nanotubes (MWCNTs) and N-octyl-pyridinium-hexafluorophosphate (OPPF(6)) ionic liquid composite on a glassy carbon (GC) electrode is described. The MWCNTs/OPPF(6) composite contributed new properties to electrochemical sensors by combining the advantages of both ionic liquids and MWCNTs. Compared with bare GC electrode, the electrocatalytic activity of MWCNTs/OPPF(6) generated a greatly improved electrochemical detection of sulfadiazine including low oxidation potential, high current responses, and good anti-fouling performance. The oxidation peak currents of sulfadiazine obtained on the MWCNTs/OPPF(6) coated GC electrode were proportional to the concentration of sulfadiazine within the range of 3.3-35.4 μM with a detection limit of 0.21 μM. PMID:21953836

  5. On-chip purification via liquid immersion of arc-discharge synthesized multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hokkanen, Matti J.; Lautala, Saara; Shao, Dongkai; Turpeinen, Tuomas; Koivistoinen, Juha; Ahlskog, Markus

    2016-07-01

    Arc-discharge synthesized multiwalled carbon nanotubes (AD-MWNT) have been proven to be of high quality, but their use is very limited due to difficulties in obtaining them in a clean and undamaged form. Here, we present a simple method that purifies raw AD-MWNT material in laboratory scale without damage, and that in principle can be scaled up. The method consists of depositing raw AD-MWNT material on a flat substrate and immersing the substrate slowly in water, whereby the surface tension force of the liquid-substrate contact line selectively sweeps away the larger amorphous carbon debris and leaves relatively clean MWNTs on the substrate. We demonstrate the utility of the method by preparing clean individual MWNTs for measurement of their Raman spectra. The spectra exhibit the characteristics of high-quality tubes free from contaminants. We also show how one concomitantly with the purification process can obtain large numbers of clean suspended MWNTs.

  6. Preparation and Characterization of Iodine-doped Multi-wall Carbon Nanotubes

    SciTech Connect

    Zainal, N. F. A.; Kudin, T. I. Tunku; Azira, A.; Ahmed, A. Z.; Abdullah, S.; Rusop, M.

    2008-05-20

    Multi-wall carbon nanotubes (MWCNTs) were synthesized by thermal chemical vapor deposition (CVD) and were intercalated with iodine at several different temperatures. Iodine doping was achieved by immersing the nanotubes in molten iodine. The sample produced was characterized by means of infrared IR as a point to the presence of covalent C-I bonds in the sample with retention of the sp{sup 2}-hybridizated carbon atoms. For all samples doped at different temperatures, the C-I bonding happen to occur based on IR spectra which was indicated by peaks around 600-650 cm{sup -1}. X-ray diffraction (XRD) characterization was used to study on the crystallinity of the undoped and iodine-doped MWCNTs. It was shown that, iodine-doping of the MWCNTs gives significant changes in the XRD spectra compared to the undoped MWCNTs. With various doping temperature, the XRD spectra shows the different crystallinity.

  7. Reinforcement of CVD grown multi-walled carbon nanotubes by high temperature annealing

    NASA Astrophysics Data System (ADS)

    Elumeeva, K. V.; Kuznetsov, V. L.; Ischenko, A. V.; Smajda, R.; Spina, M.; Forró, L.; Magrez, A.

    2013-11-01

    We report on the increase of the Young's modulus (E) of chemical vapor deposition (CVD) grown multi-walled carbon nanotubes (MWNTs) upon high temperature heat treatment. The post heat-treatment at 2200-2800°C in a controlled atmosphere results in a considerable improvement of the microstructure, chemical stability and electro-physical properties of the nanotubes. The Young's modulus of MWNTs of different diameters was measured by the deflection of a single tube suspended across the hole of silicon nitride membrane and loaded by an atomic force microscope tip. Contrary to previous reports, a strong increase of E was feasible due to the improved growth conditions of pristine carbon nanotubes and to the improved heat treatment conditions. However, the elastic modulus of CVD grown MWNTs still shows strong diameter dependence resulting from the remaining structural inhomogeneities in large diameter nanotubes.

  8. Elastic Response and Failure Studies of Multi-Wall Carbon Nanotube Twisted Yarns

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.

    2007-01-01

    Experimental data on the stress-strain behavior of a polymer multiwall carbon nanotube (MWCNT) yarn composite are used to motivate an initial study in multi-scale modeling of strength and stiffness. Atomistic and continuum length scale modeling methods are outlined to illustrate the range of parameters required to accurately model behavior. The carbon nanotubes yarns are four-ply, twisted, and combined with an elastomer to form a single-layer, unidirectional composite. Due to this textile structure, the yarn is a complicated system of unique geometric relationships subjected to combined loads. Experimental data illustrate the local failure modes induced by static, tensile tests. Key structure-property relationships are highlighted at each length scale indicating opportunities for parametric studies to assist the selection of advantageous material development and manufacturing methods.

  9. 40 CFR 721.10266 - Multi-walled carbon nanotubes (generic) (P-08-733 and P-08-734).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... matrix (does not include slurries) that is not intended to undergo further processing, except for mechanical processing. (2) The significant new uses are: (i) Protection in the workplace. Requirements as... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes...

  10. Resistivity reduction of boron-doped multiwalled carbon nanotubes synthesized from a methanol solution containing boric acid

    NASA Astrophysics Data System (ADS)

    Ishii, Satoshi; Watanabe, Tohru; Ueda, Shinya; Tsuda, Shunsuke; Yamaguchi, Takahide; Takano, Yoshihiko

    2008-05-01

    Boron-doped multiwalled carbon nanotubes (MWNTs) were synthesized using a methanol solution of boric acid as a source material. Accurate measurements of the electrical resistivity of an individual boron-doped MWNT was performed with a four-point contact, which was fabricated using an electron beam lithography technique. The doped boron provides conduction carriers, which reduces the resistivity of the MWNT.

  11. Effect of Acid and Alcohol Network Forces within Functionalized Multiwall Carbon Nanotubes Bundles on Adsorption of Copper (II) Species

    EPA Science Inventory

    Adsorption of metals on carbon nanotubes (CNTs) has important applications in sensors, membranes, and water treatment. The adsorptive capacity of multiwall CNTs for copper species in water depends on the type of functional group present on their surface. The alcohol (COOH) and ac...

  12. 40 CFR 721.10277 - Single-walled and multi-walled carbon nanotubes (generic) (P-10-40).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... nanotubes (generic) (P-10-40). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as single-walled and multi-walled carbon nanotubes (PMN P-10-40... nanotubes (generic) (P-10-40). 721.10277 Section 721.10277 Protection of Environment...

  13. Transport and retention of multi-walled carbon nanotubes in saturated porous media: Effects of input concentration and grain size

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water-saturated column experiments were conducted to investigate the effect of input concentration (Co) and sand grain size on the transport and retention of low concentrations (1, 0.01, and 0.005 mg L/1) of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNT) under repulsive electrostat...

  14. ZnO Functionalization of Multi-walled Carbon Nanotubes for Methane Sensing at Single Parts Per Million Concentration Levels

    EPA Science Inventory

    This paper presents a novel atomic layer deposition (ALD) based ZnO functionalization of surface pre-treated multi-walled carbon nanotubes (MWCNTs) for highly sensitive methane chemoresistive sensors. The temperature optimization of the ALD process leads to enhanced ZnO nanopart...

  15. Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mortazavi, Seyedeh; Novinrooz, Abdul; Reyhani, Ali; Mirershadi, Soghra

    2010-12-01

    Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs' diameter.

  16. Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mortazavi, Seyedeh Z.; Novinrooz, Abdul J.; Reyhani, Ali; Mirershadi, Soghra

    2010-12-01

    Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs’ diameter.

  17. Nanocomposites of nitrile (NBR) rubber with multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Warasitthinon, Nuthathai

    Nanotechnology offers the promise of creating new materials with enhanced performance. There are different kinds of fillers used in rubber nanocomposites, such as carbon black, silica, carbon fibers, and organoclays. Carbon nanotube reinforced elastomers have potential for improved rubber properties in aggressive environments. The first chapter is an introduction to the literature. The second chapter investigated the incorporation of multi-walled carbon nanotubes (MWCNTs) into rubber matrix for potential use in high temperature applications. The vulcanization kinetics of acrylonitrile butadiene rubber (NBR) reinforced with multi-walled carbon nanotubes was investigated. The vulcanized NBR rubber with different loading percentages of MWCNTs was also compared to NBR reinforced with carbon black N330. The optimum curing time at 170°C (T90) was found to decrease with increasing content of MWCNTs. Increased filler loading of both carbon black and MWCNTs gave higher modulus and strength. The MWCNTs filled materials gave better retention of modulus and tensile strength at high temperatures, but lower strength as compared to the carbon black filled samples. In the third chapter, carbon black (CB, 50phr) content in nitrile rubber (NBR) nanocomposites was partially replaced by multi-walled carbon nanotubes (MWCNTs). NBR/CB/CNTs nanocomposites with varying ratio of CB/CNTs (50/0 phr to 40/10 phr) were formulated via the melt-mixing method using an internal mixer. The reinforcing effect of single filler (CB) and mixture of fillers (CB and CNTs) on the properties of NBR nanocomposites was investigated. The cure kinetics and bound rubber content were analyzed using rheometry and solvent swelling method. In addition, mechanical behavior at both room temperature and high temperature (350°F/ 121°C) were examined. The scorch time and curing time values showed that there was no significant effect on the curing behavior of NBR nanocomposites after the partial replacement of CB with

  18. Mass production of multi-wall carbon nanotubes by metal dusting process with high yield

    SciTech Connect

    Ghorbani, H.; Rashidi, A.M.; Rastegari, S.; Mirdamadi, S.; Alaei, M.

    2011-05-15

    Research highlights: {yields} Synthesis of carbon nanotubes over Fe-Ni nanoparticles supported alloy 304L. {yields} Production of carbon nanotubes with high yield (700-1000%) and low cost catalyst. {yields} Optimum growth condition is CO/H{sub 2} = 1/1, 100 cm{sup 3}/min, at 620 {sup o}C under long term repetitive thermal cycling. {yields} Possibility of the mass production by metal dusting process with low cost. -- Abstract: Carbon nanotube materials were synthesized over Fe-Ni nanoparticles generated during disintegration of the surface of alloy 304L under metal dusting environment. The metal dusting condition was simulated and optimized through exposing stainless steel samples during long term repetitive thermal cycling in CO/H{sub 2} = 1/1, total gas flow rate 100 cm{sup 3}/min, at 620 {sup o}C for 300 h. After reaction, surface morphology of the samples and also carbonaceous deposition which had grown on sample surfaces were examined by stereoscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that multi-wall carbon nanotubes could be formed over nanocatalyst generated on the alloy surface by exploiting metal dusting process. By optimization of reaction parameters the yields of carbon nanotube materials obtained were 700-1000%. Also it has been shown herein that the amount of carbon nanotube materials remarkably increases when the reaction time is extended up to 300 h, indicating a possibility of the mass production by this easy method.

  19. MICROWAVE-ASSISTED SYNTHESIS OF CROSSLINKED POLY(VINYL ALCOHOL) NANOCOMPOSITES COMPRISING SINGLE-WALLED CARBON NANOTUBES, MULTI-WALLED CARBON NANOTUBES AND BUCKMINSTERFULLERENE

    EPA Science Inventory

    We report a facile method to accomplish cross-linking reaction of poly (vinyl alcohol) (PVA) with single-wall carbon nanotubes (SWNT), multi-wall carbon nanotubes (MWNT), and Buckminsterfullerene (C-60) using microwave (MW) irradiation. Nanocomposites of PVA cross-linked with SW...

  20. Ultrathin transparent conductive films of polymer-modified multiwalled carbon nanotubes.

    PubMed

    Bocharova, Vera; Kiriy, Anton; Oertel, Ulrich; Stamm, Manfred; Stoffelbach, François; Jérôme, Robert; Detrembleur, Christophe

    2006-08-01

    Deposition of multiwalled carbon nanotubes modified by poly(2-vinylpyridine) (CNT-g-P2VP) from aqueous dispersions at low pH is an effective method to prepare homogeneous ultrathin films with a tunable CNTs density. A percolation threshold of 0.25 mug/cm2 and a critical exponent alpha = 1.24 have been found from dc conductivity measurements. The sheet resistance value agrees with the percolation theory for 2D films. According to AFM and electrical measurements, even when only 5% of the surface is covered by CNT-g-P2VPs, the sheet resistance is of the order of 1 MOmega/sq, which indicates that conductivity is imparted by a network of an ultralow density. When the film transmittance decreases down to approximately 70% at 550 nm, the occupied surface area is approximately 15% and sheet resistance falls down to approximately 90 kOmega/sq. These data show that undesired in-plane clustering does not occur upon the dispersion casting of the films and that high-quality networks of CNT-g-P2VPs are built up. The electrosteric stabilization of the CNT-g-P2VP dispersions in water at low pH is at the origin of this desired behavior. Although the multiwalled CNT films prepared in this work are less conductive and less transparent than the SWNTs films, they could find applications, e.g., in touch screens, reflective displays, EMI shielding, and static charge dissipation. PMID:16869566

  1. Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines

    SciTech Connect

    Zhao, Junhua E-mail: timon.rabczuk@uni-weimar.de; Lu, Lixin; Rabczuk, Timon E-mail: timon.rabczuk@uni-weimar.de

    2014-05-28

    Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] and Machado et al. [Phys. Rev. Lett. 110, 105502 (2013)] reported the experimental and molecular dynamics realization of S-like shaped single-walled carbon nanotubes (CNTs), the so-called CNT serpentines. We reported here results from continuum modeling of the binding energy γ between different single- and multi-walled CNT serpentines and substrates as well as the mechanical stability of the CNT serpentine formation. The critical length for the mechanical stability and adhesion of different CNT serpentines are determined in dependence of E{sub i}I{sub i}, d, and γ, where E{sub i}I{sub i} and d are the CNT bending stiffness and distance of the CNT translation period. Our continuum model is validated by comparing its solution to full-atom molecular dynamics calculations. The derived analytical solutions are of great importance for understanding the interaction mechanism between different single- and multi-walled CNT serpentines and substrates.

  2. Growth of multiwalled carbon nanotube arrays by chemical vapour deposition over iron catalyst and the effect of growth parameters

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, J. K.; Pandian, P. S.; Padaki, V. C.; Bhusan, H.; Rao, K. U. B.; Xie, J.; Abraham, J. K.; Varadan, V. K.

    2009-04-01

    Multiwalled carbon nanotube (CNT) arrays were grown by catalytic thermal decomposition of acetylene, over Fe-catalyst deposited on Si-wafer in the temperature range 700-750 °C. The growth parameters were optimized to obtain dense arrays of multiwalled CNTs of uniform diameter. The vertical cross-section of the grown nanotube arrays reveals a quasi-vertical alignment of the nanotubes. The effect of varying the thickness of the catalyst layer and the effect of increasing the growth duration on the morphology and distribution of the grown nanotubes were studied. A scotch-tape test to check the strength of adhesion of the grown CNTs to the Si-substrate surface reveals a strong adhesion between the grown nanotubes and the substrate surface. Transmission electron microscopy analysis of the grown CNTs shows that the grown CNTs are multiwalled nanotubes with a bamboo structure, and follow the base-growth mechanism.

  3. Cellular uptake mechanisms of functionalised multi-walled carbon nanotubes by 3D electron tomography imaging

    NASA Astrophysics Data System (ADS)

    Al-Jamal, Khuloud T.; Nerl, Hannah; Müller, Karin H.; Ali-Boucetta, Hanene; Li, Shouping; Haynes, Peter D.; Jinschek, Joerg R.; Prato, Maurizio; Bianco, Alberto; Kostarelos, Kostas; Porter, Alexandra E.

    2011-06-01

    Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed that MWNT-NH3+ were internalised in both phagocytic and non-phagocytic cells by any one of three mechanisms: (a) individually via membrane wrapping; (b) individually by direct membrane translocation; and (c) in clusters within vesicular compartments. At early time points following intracellular translocation, we noticed accumulation of nanotube material within various intracellular compartments, while a long-term (14-day) study using primary human macrophages revealed that MWNT-NH3+ were able to escape vesicular (phagosome) entrapment by translocating directly into the cytoplasm.Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed

  4. Growth of Vertically Aligned Carbon Nanotube Films: Single- versus Multi-walled

    NASA Astrophysics Data System (ADS)

    Gupta, Sanju; Wang, Yunyu

    2005-03-01

    Vertically aligned high density small diameter carbon nanotube films were deposited by microwave CVD technique. The iron catalyst was prepared by E-beam evaporation on thermally grown silicon dioxide n-type Si(100) substrates. Experiments show that by continuous reduction in the thickness of Fe (˜ 3-5), smaller diameter carbon nanotube can be achieved. Scanning electron and high-resolution transmission electron microscopy show that the diameter of carbon nanotubes ranged ˜ 1 - 5 nm and the films are comprised of both the single- and double-wall carbon nanotubes. Visible Raman spectroscopy was used to further verify the diameter of nanotubes. A thick iron film (80 nm) was also used to grow nanotubes for comparison. The results show that the catalyst islands become greater than hundred nanometers with increasing thickness and induce multi-wall and bamboo-like microstructures. While for thinner layer of iron films smaller sizes of catalyst particles/droplets produce hollow concentric tubes without bamboo structure and with less number of walls (single-wall and double-wall carbon nanotubes). The base growth was the most appropriate model to describe the growth mechanism for our films. The electron field emission properties such as field electron emission microscopy (FEEM) in conjunction with the temperature dependence (T-FEEM) were measured to investigate the emission site density and their intensity variation. These findings in terms of the role of adsorption will be briefly discussed.

  5. Dispersion of multi-wall carbon nanotubes in polyhistidine: characterization and analytical applications.

    PubMed

    Dalmasso, Pablo R; Pedano, María L; Rivas, Gustavo A

    2012-01-13

    We report for the first time the use of polyhistidine (Polyhis) to efficiently disperse multiwall carbon nanotubes (MWCNTs). The optimum dispersion MWCNT-Polyhis was obtained by sonicating for 30 min 1.0 mg mL(-1) MWCNTs in 0.25 mg mL(-1) Polyhis solution prepared in 75:25 (v/v) ethanol/0.200 M acetate buffer solution pH 5.00. The dispersion was characterized by scanning electron microscopy, and by cyclic voltammetry and amperometry using ascorbic acid as redox marker. The modification of glassy carbon electrodes with MWCNT-Polyhis produces a drastic decrease in the overvoltage for the oxidation of ascorbic acid (580 mV) at variance with the response observed at glassy carbon electrodes modified just with Polyhis, where the charge transfer is more difficult due to the blocking effect of the polymer. The reproducibility for the sensitivities obtained after 10 successive calibration plots using the same surface was 6.3%. The MWCNT-modified glassy carbon electrode demonstrated to be highly stable since after 45 days storage at room temperature the response was 94.0% of the original. The glassy carbon electrode modified with MWCNT-Polyhis dispersion was successfully used to quantify dopamine or uric acid at nanomolar levels, even in the presence of large excess of ascorbic acid. Determinations of uric acid in human blood serum samples demonstrated a very good correlation with the value reported by Wienner laboratory. PMID:22123112

  6. Multi-walled carbon nanotubes as electrode material for microbial fuel cells.

    PubMed

    Thepsuparungsikul, N; Phonthamachai, N; Ng, H Y

    2012-01-01

    The microbial fuel cell (MFC) is a novel and innovative technology that could allow direct harvesting of energy from wastewater through microbial activity with simultaneous oxidation of organic matter in wastewater. Among all MFC parts, electrode materials play a crucial role in electricity generation. A variety of electrode materials have been used, including plain graphite, carbon paper and carbon cloth. However, these electrode materials generated only limited electricity or power. Recently, many research studies have been conducted on carbon nanotubes (CNTs) because of their unique physical and chemical properties that include high conductivity, high surface area, corrosion resistance, and electrochemical stability. These properties make them extremely attractive for fabricating electrodes and catalyst supports. In this study, CNT-based electrodes had been developed to improve MFC performance in terms of electricity generation and treatment efficiency. Multi-walled carbon nanotubes (MWCNTs) with carboxyl groups have been employed to fabricate electrodes for single-chamber air-cathode MFCs. The quality of the prepared MWCNTs-based electrodes was evaluated by morphology, electrical conductivity and specific surface area using a field emission scanning electron microscope, four-probe method and Brunauer-Emmerr-Teller method, respectively. The performance of MFCs equipped with MWCNT-based electrodes was evaluated by chemical analysis and electrical monitoring and calculation. In addition, the performance of these MFCs, using MWCNTs as electrodes, was compared against that using commercial carbon cloth. PMID:22437017

  7. Silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine for carbon dioxide capture under the flue gas condition

    SciTech Connect

    Lee, Min-Sang; Park, Soo-Jin

    2015-03-15

    In this study, silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine (PEI) were prepared via a two-step process: (i) hydrolysis of tetraethylorthosilicate onto multi-walled carbon nanotubes, and (ii) impregnation of PEI. The adsorption properties of CO{sub 2} were investigated using CO{sub 2} adsorption–desorption isotherms at 298 K and thermogravimetric analysis under the flue gas condition (15% CO{sub 2}/85% N{sub 2}). The results obtained in this study indicate that CO{sub 2} adsorption increases after impregnation of PEI. The increase in CO{sub 2} capture was attributed to the affinity between CO{sub 2} and the amine groups. CO{sub 2} adsorption–desorption experiments, which were repeated five times, also showed that the prepared adsorbents have excellent regeneration properties. - Graphical abstract: Fabrication and CO{sub 2} adsorption process of the S-MWCNTs impregnated with PEI. - Highlights: • Silica coated-MWCNT impregnated with PEI was synthesized. • Amine groups of PEI gave CO{sub 2} affinity sites on MWCNT surfaces. • The S-MWCNT/PEI(50) exhibited the highest CO{sub 2} adsorption capacity.

  8. Electrical and morphological characterization of multiwalled carbon nanotubes functionalized via the Bingel reaction

    NASA Astrophysics Data System (ADS)

    Brković, Danijela V.; Ivić, Milka L. Avramov; Rakić, Vesna M.; Valentini, Luca; Uskoković, Petar S.; Marinković, Aleksandar D.

    2015-08-01

    Covalent sidewall functionalization of multiwalled carbon nanotubes (MWCNTs) has been performed using two approaches, direct and indirect cycloaddition through diethyl malonate, based on the Bingel reaction. The results revealed that functionalized MWCNTs demonstrated enhanced electrical properties and significantly lower sheet resistance, especially after electric field thermal assisted annealing at 80 °C was performed. The presence of 1,3-dicarbonyl compounds caused the surface of MWCNTs to be more hydrophilic, approachable for the electrolyte and improved the capacitance performance of Au/MWCNTs electrodes. The modified MWCNTs have been incorporated into nanocomposites by using solution mixing method with polyaniline and drop-casting resulting mixture on the paper substrate. The reduction in the sheet resistance with increasing the content of MWCNTs in the prepared nanocomposite films has been achieved.

  9. Adsorption of Arsenic on Multiwall Carbon Nanotube–Zirconia Nanohybrid for Potential Drinking Water Purification

    PubMed Central

    AddoNtim, Susana; Mitra, Somenath

    2012-01-01

    The adsorptive removal of arsenic from water using a multiwall carbon nanotube-zirconia nanohybrid (MWCNT-ZrO2) is presented. The MWCNT-ZrO2 with 4.85% zirconia was effective in meeting the drinking water standard levels of 10 μg L−1. The absorption capacity of the composite were 2000 μg g−1 and 5000 μg g−1 for As (III) and As (V) respectively, which were significantly higher than those reported previously for iron oxide coated MWCNTs. The adsorption of As (V) on MWCNT-ZrO2 was faster than that of As (III), and a pseudo-second order rate equation effectively described the uptake kinetics. The adsorption isotherms for As (III) and As (V) fitted both the Langmuir and Freundlich models. A major advantage of the MWCNT-ZrO2 was that the adsorption capacity was not a function of pH. PMID:22424815

  10. Electron paramagnetic resonance as a quantitative tool for the study of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Coleman, J. N.; O'Brien, D. F.; Dalton, A. B.; McCarthy, B.; Lahr, B.; Barklie, R. C.; Blau, W. J.

    2000-12-01

    We have described a method that maximizes the phase separation of graphitic particles (GP) and multiwalled carbon nanotubes (MWNT) in solutions of various organic polymeric hosts. This involves the formation of sediment and a solute. These components were characterized for MWNT and GP content using electron paramagnetic resonance (EPR) measurements. All EPR signals could be deconvoluted into nanotube and GP components. When normalized, these components are representative of the mass of MWNT and GP present. This allows us to make quantitative measurements of nanotube and GP content in different environments. The most successful polymer host was poly (m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) (PmPV). In this case the solute contained 63% of the added nanotubes with only 2% of the added graphite remaining.