Science.gov

Sample records for metallic single-wall carbon

  1. Metallic single-walled carbon nanotubes for conductive nanocomposites.

    PubMed

    Wang, Wei; Fernando, K A Shiral; Lin, Yi; Meziani, Mohammed J; Veca, L Monica; Cao, Li; Zhang, Puyu; Kimani, Martin M; Sun, Ya-Ping

    2008-01-30

    This article reports an unambiguous demonstration that bulk-separated metallic single-walled carbon nanotubes offer superior performance (consistently and substantially better than the as-produced nanotube sample) in conductive composites with poly(3-hexylthiophene) and also in transparent conductive coatings based on PEDOT:PSS. The results serve as a validation on the widely held view that the carbon nanotubes are competitive in various technologies currently dominated by conductive inorganic materials (such as indium tin oxide). PMID:18173271

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

    DOEpatents

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

    2007-01-09

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

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

    SciTech Connect

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

    2014-05-12

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

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

    NASA Technical Reports Server (NTRS)

    Sun, Ya-Ping (Inventor)

    2008-01-01

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

  5. Filling single-wall carbon nanotubes with d- and f-metal chloride and metal nanowires.

    PubMed

    Satishkumar, B C; Taubert, A; Luzzi, D E

    2003-01-01

    Nanowires of magnetic metals (Fe, Co, Ho, Gd) have been synthesized inside the hollow interiors of single-wall carbon nanotubes (SWNTs) by filling SWNTs with precursor metal chlorides and subsequent reduction. SWNTs have been filled by either the melt-phase sealed-tube reaction or a solution-phase method. Among the metal chlorides investigated in this study, HoCl3 and GdCl3 filled the SWNTs to a significantly higher extent. The nanowires have been imaged by transmission electron microscopy (TEM), high-resolution transmission electron microscopy, and scanning transmission electron microscopy (STEM). X-ray energy dispersive spectroscopy carried out in conjunction with TEM and STEM confirmed the presence of metal chloride and metal nanowires. PMID:12908245

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

    PubMed

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

    2014-10-21

    Nitrogen-doped (N-doped) single-wall carbon nanotubes (SWCNTs) were synthesized by chemical vapor deposition using SiOx nanoparticles as a catalyst and ethylenediamine as the source of both carbon and nitrogen. The N-doped SWCNTs have a mean diameter of 1.1 nm and a narrow diameter range, with 92% of them having diameters from 0.7 to 1.4 nm. Multi-wavelength laser Raman spectra and temperature-dependent electrical resistance indicate that the SWCNT sample is enriched with metallic nanotubes. These N-doped SWCNTs showed excellent electrocatalytic activity for the oxygen reduction reaction and highly selective and sensitive sensing ability for dopamine detection. PMID:25189467

  7. Selective interaction of a soluble pentacene derivative with metallic single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, Cai-Hong; Liu, Yi-Yang; Zhang, Yong-Hui; Wei, Rui-Rui; Li, Bing-Rui; Zhang, Hao-Li; Chen, Yong

    2009-03-01

    We report a soluble pentacene derivative, 6,13-bis(2-(trimethylsilyl)ethynyl)pentacene, can be used for efficient extraction of metallic single-walled carbon nanotubes (SWCNTs), which is proven by resonance Raman spectroscopy (RRS), Vis-NIR absorption spectroscopy and conductivity measurements. RRS studies reveal that the separation is solvent-dependent and is more efficient for small diameter tubes. Theoretical simulation suggests that the adsorption of pentacene on (7, 7) metallic SWCNT is about 34% more favorable than that on (13, 0) semiconducting SWCNT. This work provides a new direction in seeking reagents to facilitate high efficiency and nondestructive separation of metallic and semiconducting SWCNTs.

  8. Step-edge faceting and local metallization of a single-wall semiconducting carbon nanotube

    NASA Astrophysics Data System (ADS)

    Clair, Sylvain; Kim, Yousoo; Kawai, Maki

    2011-10-01

    The adsorption of a single-wall carbon nanotube on a well-defined metal surface produces substantial mutual interaction that can lead to strong effects both on the nanotube and on the substrate side. We report two kinds of step faceting on Au(111) and Cu(111). We observed local metallization of a semiconducting nanotube induced by the deformation pressure of crossing a step edge on Cu(111). The origin of this effect is discussed. Our results illustrate the complexity and the large number of situations encountered for the nanotube-on-metal system.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  10. Photogenerated Free Carrier Dynamics in Metal and Semiconductor Single-Walled Carbon Nanotube Films

    SciTech Connect

    Beard, M. C.; Blackburn, J. L.; Heben, M. J.

    2008-01-01

    Time-resolved THz spectroscopy (TRTS) is employed to study the photogenerated charge-carrier dynamics in transparent films of single-walled carbon nanotubes (SWNTs). Two films were investigated: a film with 94% semiconducting-type tubes (s-SWNTs) and a film with only 7% s-SWNT and 93% metal-type tubes (m-SWNTs). We conclude that charge-carriers are generated with >60% yields at low light intensities in both films. Free-carriers are generated by a linear exciton dissociation process that occurs within 1 ps and is independent of excitation wavelength or tube type.

  11. Controlled Growth of Semiconducting and Metallic Single-Wall Carbon Nanotubes.

    PubMed

    Liu, Chang; Cheng, Hui-Ming

    2016-06-01

    Single-wall carbon nanotubes (SWCNTs) can be either semiconducting or metallic depending on their chiral angles and diameters. The use of SWCNTs in electronics has long been hindered by the fact that the as-prepared SWCNTs are usually a mixture of semiconducting and metallic ones. Therefore, controlled synthesis of SWCNTs with a uniform electrical type or even predefined chirality has been a focus of carbon nanotube research in recent years. In this Perspective, we summarize recent progress on the controlled growth of semiconducting and metallic SWCNTs by in situ selective etching and by novel catalyst design. The advantages and mechanisms of these approaches are analyzed, and the challenges are discussed. Finally, we predict possible breakthroughs and future trends in the controlled synthesis and applications of SWCNTs. PMID:27149629

  12. Selective electroless coating of palladium nanoparticles on metallic single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Feng, Yiyu; Lv, Peng; Zhang, Xuequan; Li, Yu; Feng, Wei

    2010-08-01

    The selective electroless coating of palladium (Pd) nanoparticles on metallic single-walled carbon nanotube (SWNT) was studied. The remarkable increase in conductivity of SWNT/Pd films up to fourfold higher than pure SWNT was due to p-type doping and Ohmic contact. Metallic behavior of SWNT/Pd-Field effect transistor (on/off ratio=1.2) was attributed to more hole carriers and no electrostatic barrier between nanotube and Pd. G-band and radial breathing mode in Raman indicates a definitive increase in the proportion of metallic SWNT. Results indicate Pd are selectively coated on metallic SWNT with more negative potential allowing for the electroless Pd2+ reduction.

  13. Colored semitransparent conductive coatings consisting of monodisperse metallic single-walled carbon nanotubes.

    PubMed

    Green, Alexander A; Hersam, Mark C

    2008-05-01

    Single-walled carbon nanotubes (SWNTs) are promising materials for transparent conduction as a result of their exceptional electrical, optical, mechanical, and chemical properties. However, since current synthetic methods yield polydisperse mixtures of SWNTs, the performance of SWNT transparent conductive films has previously been hindered by semiconducting species. Here, we describe the performance of transparent conductors produced using predominantly metallic SWNTs. Compared with unsorted material, films enriched in metallic SWNTs can enhance conductivity by factors of over 5.6 in the visible and 10 in the infrared. Moreover, by using monodisperse metallic SWNTs sorted with angstrom-level resolution in diameter, semitransparent conductive coatings with tunable optical transmittance can be produced. PMID:18393537

  14. TRANSPORT SPECTROSCOPY OF CHEMICAL NANOSTRUCTURES: The Case of Metallic Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Liang, Wenjie; Bockrath, Marc; Park, Hongkun

    2005-05-01

    Transport spectroscopy, a technique based on current-voltage measurements of individual nanostructures in a three-terminal transistor geometry, has emerged as a powerful new tool to investigate the electronic properties of chemically derived nanostructures. In this review, we discuss the utility of this approach using the recent studies of single-nanotube transistors as an example. Specifically, we discuss how transport measurements can be used to gain detailed insight into the electronic motion in metallic single-walled carbon nanotubes in several distinct regimes, depending on the coupling strength of the contacts to the nanotubes. Measurements of nanotube devices in these different conductance regimes have enabled a detailed analysis of the transport properties, including the experimental determination of all Hartree-Fock parameters that govern the electronic structure of metallic nanotubes and the demonstration of Fabry-Perot resonators based on the interference of electron waves.

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

    NASA Astrophysics Data System (ADS)

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

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

  16. A Facile Route to Metal Oxides/Single-Walled Carbon Nanotube Macrofilm Nanocomposites for Energy Storage

    NASA Astrophysics Data System (ADS)

    Cao, Zeyuan; Wei, Bingqing

    2015-05-01

    Nanocomposites consisting of transition-metal oxides and carbon nanomaterials with a desired size and structure are highly demanded for high performance energy storage devices. Here, a facile two-step and cost-efficient approach relying on directly thermal treatment of chemical-vapor-deposition products is developed as a general synthetic method to prepare a family of metal oxides (MxOy (M=Fe, Co, Ni))/single-walled carbon nanotube (SWNT) macrofilm nanocomposites. The MxOy nanoparticles obtained are of 3-17 nm in diameter and homogeneously anchor on the free-standing SWNT macrofilms. NiO/SWNT also exhibits a high specific capacitance of 400 F g-1 and fast charge-transfer Faradaic redox reactions to achieve asymmetric supercapacitors with a high power and energy density. All MxOy/SWNT nanocomposites could deliver a high capacity beyond 1000 mAh g-1 and show excellent cycling stability for lithium-ion batteries. The impressive results demonstrate the promise for energy storage devices and the general approach may pave the way to synthesize other functional nanocomposites.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    SciTech Connect

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

    2015-04-28

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

  19. Single walled carbon nanotube-metal oxide nanocomposites for reversible and reproducible storage of hydrogen.

    PubMed

    Silambarasan, D; Surya, V J; Vasu, V; Iyakutti, K

    2013-11-13

    Composite material consisting of single walled carbon nanotubes (SWCNTs) and metal oxide nanoparticles has been prepared and their hydrogen storage performance is evaluated. Metal oxides such as tin oxide (SnO2), tungsten trioxide (WO3), and titanium dioxide (TiO2) are chosen as the composite constituents. The composites have been prepared by means of ultrasonication. Then, the composite samples are deposited on alumina substrates and at 100 °C in a Sieverts-like hydrogenation setup. Characterization techniques such as transmission electron microscopy (TEM), Raman spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, energy dispersive spectroscopy (EDS), CHN elemental analysis, and thermogravimetric (TG) measurements are used to analyze the samples at various stages of experiments. Hydrogen storage capacity of the composites namely, SWCNT-SnO2, SWCNT-WO3, and SWCNT-TiO2 are found to be 1.1, 0.9, and 1.3 wt %, respectively. Hydrogenated composite samples are stable at room temperature and desorption of hydrogen is found to be 100% reversible. Desorption temperature ranges and binding energy ranges of hydrogen have been measured from the desorption studies. The hydrogenation, dehydrogenation temperature, and binding energy of hydrogen fall in the recommended range of a suitable hydrogen storage medium applicable for fuel cell applications. Reproducibility and deterioration level of the composite samples have also been examined. PMID:24117025

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

    NASA Astrophysics Data System (ADS)

    Zeng, Qiang

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

  1. Gate-Free Electrical Breakdown of Metallic Pathways in Single-Walled Carbon Nanotube Crossbar Networks.

    PubMed

    Li, Jinghua; Franklin, Aaron D; Liu, Jie

    2015-09-01

    Aligned single-walled carbon nanotubes (SWNTs) synthesized by the chemical vapor deposition (CVD) method have exceptional potential for next-generation nanoelectronics. However, the coexistence of semiconducting (s-) and metallic (m-) SWNTs remains a considerable challenge since the latter causes significant degradation in device performance. Here we demonstrate a facile and effective approach to selectively break all m-SWNTs by stacking two layers of horizontally aligned SWNTs to form crossbars and applying a voltage to the crossed SWNT arrays. The introduction of SWNT junctions amplifies the disparity in resistance between s- and m-pathways, leading to a complete deactivation of m-SWNTs while minimizing the degradation of the semiconducting counterparts. Unlike previous approaches that required an electrostatic gate to achieve selectivity in electrical breakdown, this junction process is gate-free and opens the way for straightforward integration of thin-film s-SWNT devices. Comparison to electrical breakdown in junction-less SWNT devices without gating shows that this junction-based breakdown method yields more than twice the average on-state current retention in the resultant s-SWNT arrays. Systematic studies show that the on/off ratio can reach as high as 1.4 × 10(6) with a correspondingly high retention of on-state current compared to the initial current value before breakdown. Overall, this method provides important insight into transport at SWNT junctions and a simple route for obtaining pure s-SWNT thin film devices for broad applications. PMID:26263184

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  3. Scalable dielectrophoresis of single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fitzhugh, William A.

    Single Walled Carbon Nanotubes (SWNTs) have attracted much attention as a candidate material for future nano-scale 'beyond silicon' devices. However industrial scale operations have been impeded by difficulties in separating the metallic and semiconducting species. This paper addresses the use of highly inhomogeneous alternating electric fields, dielectrophoresis, to isolate SWNT species in scaled systems. Both numerical and experimental methods will be discussed.

  4. Synthesis and catalytic activity of heteroatom doped metal-free single-wall carbon nanohorns.

    PubMed

    Wu, Xiaohui; Cui, Longbin; Tang, Pei; Hu, Ziqi; Ma, Ding; Shi, Zujin

    2016-04-01

    Boron-, phosphorus-, nitrogen-doped and co-doped single-wall carbon nanohorns were produced using an arc-vaporization method. These as-prepared doped materials consist of uniform isolated nanohorns and exhibit greatly enhanced catalytic capabilities in the reduction reaction of nitrobenzene and a volcano-shape trend between their activities with a B dopant content is found. Moreover, the B-C3 and P-C3 species in doped nanohorns might act as the acidic and basic sites to promote this reaction. PMID:27006980

  5. DFT studies of low concentration substitutional doping of transition-metals on single-walled carbon nanotube surface.

    PubMed

    Mashapa, Matete G; Ray, Suprakas Sinha

    2010-12-01

    Using first principles-density functional theory, a theoretical study of the electronic properties of (5, 5) armchair single-walled carbon nanotube doped with transitions metals (Fe, Co and Ni) is presented. The generalized gradient approximation was used for the exchange-correlation potentials. The energy cut-off of 500 eV was adopted in the study. The main features of electronic band structure and density of states are shown. A systematic comparison of the density of states as well as band structures of pure and doped SWCNT is made. The contribution of the different bands was analyzed from the total and partial density of states curves. These metals are used as catalysts during synthesis of single-walled carbon nanotubes and hence, the choice we have made. Where data is available, the results are compared with previous calculations and with experimental measurements. PMID:21121313

  6. Thermoelectric Detection of Multi-Subband Density of States in Semiconducting and Metallic Single-Walled Carbon Nanotubes.

    PubMed

    Shimizu, Sunao; Iizuka, Takahiko; Kanahashi, Kaito; Pu, Jiang; Yanagi, Kazuhiro; Takenobu, Taishi; Iwasa, Yoshihiro

    2016-07-01

    Thermoelectric detection of a multi-subband density of states in semiconducting and metallic single-walled carbon nanotubes is demonstrated by scanning the Fermi energy from electron-doped to hole-doped regions. The Fermi energy is systematically controlled by utilizing the strong electric field induced in electric-double-layer transistor configurations, resulting in the optimization of the thermoelectric power factor. PMID:27191367

  7. Structure and dynamics of metallic and carburized catalytic Ni nanoparticles: effects on growth of single-walled carbon nanotubes.

    PubMed

    Gomez-Ballesteros, Jose L; Balbuena, Perla B

    2015-06-14

    Understanding the evolution of the catalyst structure and interactions with the nascent nanotube under typical chemical vapor deposition (CVD) conditions for the synthesis of single-walled carbon nanotubes is an essential step to discover a way to guide growth toward desired chiralities. We use density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations on model metallic and carburized Ni clusters to explore changes in the fundamental features of the nanocatalyst: geometric and electronic structure, dynamics and stability of the carburized nanocatalyst, and interactions with nascent nanotube caps at two different temperatures (750 and 1000 K) and different carbon composition ratios. This allows us to gain insight about the evolution of these aspects during the pre-growth and growth stages of CVD synthesis of single-walled carbon nanotubes and their implications for reactivity and control of the nanotube structure. PMID:25989515

  8. High-Yield Separation of Metallic and Semiconducting Single-Wall Carbon Nanotubes by Agarose Gel Electrophoresis

    NASA Astrophysics Data System (ADS)

    Tanaka, Takeshi; Jin, Hehua; Miyata, Yasumitsu; Kataura, Hiromichi

    2008-11-01

    We have developed a novel separation method of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) using agarose gel electrophoresis. When the SWCNTs were isolated with sodium dodecyl sulfate (SDS) and embedded in agarose gel, only the metallic SWCNTs separated from the starting gel by an electric field. After 20 min, almost all SWCNTs applied to gel electrophoresis were separated into two fractions, containing ˜95% semiconducting and ˜70% metallic nanotubes. The difference in the response to the electric field between metallic and semiconducting SWCNTs can be explained by the higher affinity of semiconducting SWCNTs to agarose than to SDS.

  9. Selective Growth of Metallic and Semiconducting Single Walled Carbon Nanotubes on Textured Silicon.

    PubMed

    Jang, Mira; Lee, Jongtaek; Park, Teahee; Lee, Junyoung; Yang, Jonghee; Yi, Whikun

    2016-03-01

    We fabricated the etched Si substrate having the pyramidal pattern size from 0.5 to 4.2 μm by changing the texturing process parameters, i.e., KOH concentration, etching time, and temperature. Single walled carbon nanotubes (SWNTs) were then synthesized on the etched Si substrates with different pyramidal pattern by chemical vapor deposition. We investigated the optical and electronic properties of SWNT film grown on the etched Si substrates of different morphology by using scanning electron microscopy, Raman spectroscopy and conducting probe atomic force microscopy. We confirmed that the morphology of substrate strongly affected the selective growth of the SWNT film. Semiconducting SWNTs were formed on larger pyramidal sized Si wafer with higher ratio compared with SWNTs on smaller pyramidal sized Si. PMID:27455748

  10. Density functional theory investigation of the VIIIB transition metal atoms deposited on (5,5) single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tabtimsai, Chanukorn; Ruangpornvisuti, Vithaya; Wanno, Banchob

    2013-03-01

    The binding of VIIIB transition metals i.e. Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt single atoms to single-walled carbon nanotube (SWCNT) was investigated using the density functional theory method. The B3LYP/LanL2DZ calculation shows that all these transition metal atoms have strong binding abilities to SWCNT. The binding abilities of these transition metals onto SWCNT are in following order: Os>Ru>Ir>Fe>Rh>Pt>Ni>Co>Pd. The Os single atom binding on SWCNT is the strongest binding of which the binding energy is -240.66 kcal/mol. The partial charge transfers from transition metal to SWCNT, density of states and energy gaps of metal atoms deposited on SWCNTs were analyzed and reported.

  11. Modification of conductive properties of (10, 0) zigzag single-walled carbon nanotubes (SWCNT) by alkali metals absorption

    NASA Astrophysics Data System (ADS)

    Hamadanian, Masood; Tavangar, Zahra; Noori, Banafsheh

    2014-11-01

    We have investigated the electronic and structural properties of (10, 0) zigzag single-walled carbon nanotubes (SWCNT) which have adsorbed different alkali metals (X: Li, Na, K, and Cs) and the hydrogen atom by using Density Functional Theory (DFT). It was discovered that among the alkali elements, Li atoms form the strongest bond with SWCNT. In addition, a significant shift was observed in the electronic state of alkali-adsorbed SWCNT compared to pristine SWCNT. Finally, it was proposed that due to showing excellent electronic structure, these modified nanotubes can be applied in new electronic devices, such as transistors, and field emission displays.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  13. Transparent Conductive Single-Walled Carbon Nanotube Networks with Precisely Tunable Ratios of Semiconducting and Metallic Nanaotubes

    SciTech Connect

    Blackburn, J. L.; Barnes, T. M.; Beard, M. C.; Kim, Y.-H.; Tenent, R. C.; McDonald, T. J.; To, B.; Coutts, T. J.; Heben, M. J.

    2008-01-01

    We present a comprehensive study of the optical and electrical properties of transparent conductive films made from precisely tuned ratios of metallic and semiconducting single-wall carbon nanotubes. The conductivity and transparency of the SWNT films are controlled by an interplay between localized and delocalized carriers, as determined by the SWNT electronic structure, tube-tube junctions, and intentional and unintentional redox dopants. The results suggest that the main resistance in the SWNT thin films is the resistance associated with tube-tube junctions. Redox dopants are found to increase the delocalized carrier density and transmission probability through intertube junctions more effectively for semiconductor-enriched films than for metal-enriched films. As a result, redox-doped semiconductor-enriched films are more conductive than either intrinsic or redox-doped metal-enriched films.

  14. Processing of single-walled carbon-nanotube metal matrix composites and a finite element model for the process

    NASA Astrophysics Data System (ADS)

    Wilson, Kenneth

    In the present investigation, single-walled carbon nanotube (SWCNT or SWNT) reinforced titanium (Ti) matrix composites have been produced by powder metallurgy (PM) and induction heating methods. It has been found that a nickel coating and a fast processing time associated with the induction heating method enables carbon nanotubes to survive the high-temperature (above 1950 K) processing conditions. The result has been a Ti-SWCNT metal-matrix composite (MMC) which is three times stronger and harder than Ti alone, a consequence that has never been accomplished before. This is a promising new development in the application of SWCNT technology to materials science. A mathematical model is given to support the experimental findings.

  15. Discovery of surfactants for metal/semiconductor separation of single-wall carbon nanotubes via high-throughput screening.

    PubMed

    Tanaka, Takeshi; Urabe, Yasuko; Nishide, Daisuke; Kataura, Hiromichi

    2011-11-01

    We report novel surfactants that can be used for the separation of metallic (M) and semiconducting (S) single-wall carbon nanotubes (SWCNTs). Among the M/S separation methods using surfactants in an aqueous solution, sodium dodecyl sulfate plays a key role in density gradient ultracentrifugation (DGU) and agarose gel separations. In this study, we screened 100 surfactants for M/S separation using a high-throughput screening system. We identified five surfactants, which could be used for both DGU and agarose gel separations, suggesting that the basic principle of these separations is common. These surfactants have relatively low dispersibilities, which is likely due to their common structural features, i.e., straight alkyl tails and charged head groups, and appeared to enable M- and S-SWCNTs to be distinguished and separated. These surfactants should stimulate research in this field and extend the application of electrically homogeneous SWCNTs not only for electronics but also for biology and medicine. PMID:21980975

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

    NASA Astrophysics Data System (ADS)

    Kharlamova, M. V.

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  18. Separation of single-walled carbon nanotubes into metallic and semiconducting groups: a simple and large-scale method

    NASA Astrophysics Data System (ADS)

    Lu, Jing; Maeda, Y.

    2006-03-01

    Separation of a large number of single-walled carbon nanotubes (SWNTs) into groups each with specifically metallic and semiconducting properties is an extremely important task for technology application. Even though effective methods (1, 2) have been devised, they suffer from drawbacks such as either the yield is low (3) or expense is high (4). In this work, we study the problem from a theoretical approach, we notice that based on the first principles calculations the binding strengths of methylamine to the semiconducting [13, 0] SWNT are only 36˜61% of that to the metallic [7, 7] SWNT, which suggests that the amines is much more attractive toward the pure metallic than the semiconducting SWNTs. Therefore starting from as-prepared SWNTs and with the assistance of amines, we achieved SWNTs with enriched metallic properties over semiconducting in a convenient and large-scale manner. References: (1) D. Chattopadhyay, L. Galeska, F. Papadimitrakopoulos, Journal of the American Chemical Society 125, 3370 (MAR 19, 2003). (2) H. P. Li et al., Journal of the American Chemical Society 126, 1014 (FEB 4, 2004). (3) R. Krupke, F. Hennrich, H. von Lohneysen, M. Kappes, SCIENCE 301, 344 (JUL 18, 2003). (4) M. Zheng et al., Science 302, 1545 (NOV 28, 2003).

  19. Effect of Lanthanide Metal Complexation on the Properties and Electronic Structure of Single-Walled Carbon Nanotube Films.

    PubMed

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

    2015-12-30

    We spectroscopically analyze the effect of e-beam deposition of lanthanide metals on the electronic structure and conductivities of films of semiconducting (SC) single-walled carbon nanotubes (SWNTs) in high vacuum. We employ near-infrared and Raman spectroscopy to interpret the changes in the electronic structure of SWNTs on exposure to small amounts of the lanthanides (Ln = Sm, Eu, Gd, Dy, Ho, Yb), based on the behavior of the reference metals (M = Li, Cr) which are taken to exemplify ionic and covalent bonding, respectively. The analysis shows that while the lanthanides are more electropositive than the transition metals, in most cases they exhibit similar conductivity behavior which we interpret in terms of the formation of covalent bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = La, Nd, Gd, Dy, Ho]. However, only M = Eu, Sm, Yb show the continually increasing conductivity characteristic of Li, and this supports our contention that these metals provide the first examples of mixed covalent-ionic bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = Sm, Eu, Yb]. PMID:25902843

  20. 3-D perpendicular assembly of single walled carbon nanotubes for complimentary metal oxide semiconductor interconnects.

    PubMed

    Kim, Tae-Hoon; Yilmaz, Cihan; Somu, Sivasubramanian; Busnaina, Ahmed

    2014-05-01

    Due to their superior electrical properties such as high current density and ballistic transport, carbon nanotubes (CNT) are considered as a potential candidate for future Very Large Scale Integration (VLSI) interconnects. However, direct incorporation of CNTs into Complimentary Metal Oxide Semiconductor (CMOS) architecture by conventional chemical vapor deposition (CVD) growth method is problematic since it requires high temperatures that might damage insulators and doped semiconductors in the underlying CMOS circuits. In this paper, we present a directed assembly method to assemble aligned CNTs into pre-patterned vias and perpendicular to the substrate. A dynamic electric field with a static offset is applied to provide the force needed for directing the SWNT assembly. It is also shown that by adjusting assembly parameters the density of the assembled CNTs can be significantly enhanced. This highly scalable directed assembly method is conducted at room temperature and pressure and is accomplished in a few minutes. I-V characterization of the assembled CNTs was conducted using a Zyvex nanomanipulator in a scanning electron microscope (SEM) and the measured value of the resistance is found to be 270 komega s. PMID:24734611

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

    SciTech Connect

    Dr. Ahn

    2004-04-30

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

  2. Long-term colloidal stability and metal leaching of single wall carbon nanotubes: effect of temperature and extracellular polymeric substances.

    PubMed

    Adeleye, Adeyemi S; Keller, Arturo A

    2014-02-01

    Long term (90 day) stability, aggregation kinetics in the presence and absence of natural organic materials (NOM), and metal leaching of five commercial single wall carbon nanotubes (SWCNTs) in waters (e.g. freshwater, seawater, stormwater, wastewater, and groundwater) were studied, as well as the effect of temperature on SWCNT stability and metal leaching. Zeta (ζ) potential of SWCNT decreased in magnitude with increase in temperature. In wastewater, SWCNT sedimented from the water column to below detectable levels after 30 days when kept at 40 °C, but at 20 °C 19% suspension was still observed after the same exposure time. Addition of 0.1 mg-C L(-1) EPS shifted the critical coagulation concentration (CCC) of SRNOM-stabilized SWCNT from 15 mM to 54 mM NaCl via additional electrostatic and possibly steric stabilization. Attachment efficiencies (α) of SWCNT in waters ranged from ∼0.001 in DI with 10 mg L(-1) SRNOM to 1 in seawater. However, sedimentation of SWCNT in seawater (and other high ionic strength conditions) was not as fast as expected due to improved buoyancy and/or drag. Purified forms of SWCNTs exhibited better dispersibility and stability in most waters, but as expected, the total metal leached out was higher in the raw variants. Metal leaching from CNT in these studies was controlled by metal and water chemistries, CNT pretreatment, leachable metal fraction, exposure time, and presence of NOM. PMID:24342047

  3. Metal nanoparticles and DNA co-functionalized single-walled carbon nanotube gas sensors

    NASA Astrophysics Data System (ADS)

    Su, Heng C.; Zhang, Miluo; Bosze, Wayne; Lim, Jae-Hong; Myung, Nosang V.

    2013-12-01

    Metal/DNA/SWNT hybrid nanostructure-based gas sensor arrays were fabricated by means of ink jet printing of metal ion chelated DNA/SWNTs on microfabricated electrodes, followed by electroless deposition to reduce metal ions to metal. DNA served as a dispersing agent to effectively solubilize pristine SWNTs in water and as metal ion chelating centers for the formation of nanoparticles. Noble metals including palladium, platinum, and gold were used because the high binding affinity toward specific analytes enhances the selectivity and sensitivity. The sensitivity and selectivity of the gas sensors toward various gases such as H2, H2S, NH3, and NO2 were determined at room temperature. Sensing results indicated the enhancement of the sensitivity and selectivity toward certain analytes by functionalizing with different metal nanoparticles (e.g., Pd/DNA/SWNTs for H2 and H2S). The combined responses give a unique pattern or signature for each analyte by which the system can identify and quantify an individual gas.

  4. Metal nanoparticles and DNA co-functionalized single-walled carbon nanotube gas sensors.

    PubMed

    Su, Heng C; Zhang, Miluo; Bosze, Wayne; Lim, Jae-Hong; Myung, Nosang V

    2013-12-20

    Metal/DNA/SWNT hybrid nanostructure-based gas sensor arrays were fabricated by means of ink jet printing of metal ion chelated DNA/SWNTs on microfabricated electrodes, followed by electroless deposition to reduce metal ions to metal. DNA served as a dispersing agent to effectively solubilize pristine SWNTs in water and as metal ion chelating centers for the formation of nanoparticles. Noble metals including palladium, platinum, and gold were used because the high binding affinity toward specific analytes enhances the selectivity and sensitivity. The sensitivity and selectivity of the gas sensors toward various gases such as H2, H2S, NH3, and NO2 were determined at room temperature. Sensing results indicated the enhancement of the sensitivity and selectivity toward certain analytes by functionalizing with different metal nanoparticles (e.g., Pd/DNA/SWNTs for H2 and H2S). The combined responses give a unique pattern or signature for each analyte by which the system can identify and quantify an individual gas. PMID:24284477

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  6. Assessing The Hydrogen Adsorption Capacity Of Single-Wall Carbon Nanotube / Metal Composites

    NASA Astrophysics Data System (ADS)

    Heben, Michael J.; Dillon, Anne C.; Gilbert, Katherine E. H.; Parilla, Philip A.; Gennett, Thomas; Alleman, Jeffrey L.; Hornyak, G. Louis; Jones, Kim M.

    2003-07-01

    Carefully controlled and calibrated experiments indicate a maximum capacity for adsorption of hydrogen on SWNTs is ˜8 wt% under room temperature and pressure conditions. Samples displaying this maximum value were prepared by sonicating purified SWNTs in a dilute nitric acid solution with a high-energy probe. The process cuts the SWNT into shorter segments and introduces a Ti-6Al-4V alloy due to the disintegration of the ultrasonic probe. The Ti-6Al-4V alloy is a well-known metal hydride and its contribution to the measured hydrogen uptake was accounted for in order to assess the amount of hydrogen stored on the SWNT fraction. The principal purpose of this paper is to present key details associated with the measurement procedures in order to illustrate the degree of rigor with which the findings were obtained.

  7. Charge transfer at junctions of a single layer of graphene and a metallic single walled carbon nanotube.

    PubMed

    Paulus, Geraldine L C; Wang, Qing Hua; Ulissi, Zachary W; McNicholas, Thomas P; Vijayaraghavan, Aravind; Shih, Chih-Jen; Jin, Zhong; Strano, Michael S

    2013-06-10

    Junctions between a single walled carbon nanotube (SWNT) and a monolayer of graphene are fabricated and studied for the first time. A single layer graphene (SLG) sheet grown by chemical vapor deposition (CVD) is transferred onto a SiO₂/Si wafer with aligned CVD-grown SWNTs. Raman spectroscopy is used to identify metallic-SWNT/SLG junctions, and a method for spectroscopic deconvolution of the overlapping G peaks of the SWNT and the SLG is reported, making use of the polarization dependence of the SWNT. A comparison of the Raman peak positions and intensities of the individual SWNT and graphene to those of the SWNT-graphene junction indicates an electron transfer of 1.12 × 10¹³ cm⁻² from the SWNT to the graphene. This direction of charge transfer is in agreement with the work functions of the SWNT and graphene. The compression of the SWNT by the graphene increases the broadening of the radial breathing mode (RBM) peak from 3.6 ± 0.3 to 4.6 ± 0.5 cm⁻¹ and of the G peak from 13 ± 1 to 18 ± 1 cm⁻¹, in reasonable agreement with molecular dynamics simulations. However, the RBM and G peak position shifts are primarily due to charge transfer with minimal contributions from strain. With this method, the ability to dope graphene with nanometer resolution is demonstrated. PMID:23281165

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  9. Separation of the semiconducting and the metallic types of single-wall carbon nanotube by electrophoresis method

    NASA Astrophysics Data System (ADS)

    Chen, Hsi-Chao; Yen, Chih-Feng; Chen, Guan-Jhen; Hsiao, Tzu-Ti; Zhou, Yang; Huang, Kuo-Ting; Lee, Hsin-Ta; Yang, Wan-Ting

    2014-09-01

    This study was to separate the semiconducting and the metallic types of single-wall carbon nanotubes (SWNTs) by electrophoresis with the different dispersants that are deoxyribonucleic acid (DNA), Triton X-100 and sodium dodecyl sulfate (SDS), respectively. The dispersants modify the surface of SWNTs and disperse in the de-ionized water. and used electric power supply 100V to electrophoresis. However, the different dispersants such as DNA, Triton X-100 and SDS coated on SWNTs have different property of electronic field. Hence, in the same power of electrophoresis was applied to separate out s-SWNT and m-SWNT from the raw-SWNT. In addition, the DNA base pair and quantitative can be determine by electrophoresis with standard mark. The electrophoresis has features that low sample need, low energy required and efficiently for this fabrication. The results of Raman spectrum could verify the separation efficiency and determine the electrical of the samples with the radial breathing mode (RBM, 100-400cm-1) of SWNT. After the dispersion process with DNA, a new peak (~1450 cm-1) has been observed between D-band (~1350cm-1) and G-band (~1550cm-1) that also can identify s-SWNT and m-SWNT.

  10. Composite films of poly(3-hexylthiophene) grafted single-walled carbon nanotubes for electrochemical detection of metal ions.

    PubMed

    Yang, Shaojun; Meng, Dongli; Sun, Jinhua; Huang, Yan; Huang, Yong; Geng, Jianxin

    2014-05-28

    In this study, we prepared electrochemically active films of poly(3-hexylthiophene) grafted single-walled carbon nanotubes (SWNT-g-P3HT) by using a modified vacuum-assisted deposition approach, in which a SWNT-g-P3HT composite layer of various thicknesses was deposited on the top of a thin SWNT layer. Measurement of the optical and electrical properties of the SWNT-g-P3HT composite films demonstrated that the thickness of the SWNT-g-P3HT composite films was controllable. The data of transmission electron microscope observation and Raman spectroscopy indicated that the covalent grafting of P3HT onto the surfaces of SWNTs resulted in intimate and stable connectivity between the two components in the SWNT-g-P3HT composite. Capitalizing on these unique features, we successfully developed a new class of electrochemical sensors that used the SWNT-g-P3HT composite films deposited on an indium-tin oxide substrate as an electrochemical electrode for detection of metal ions. Significantly, such a SWNT-g-P3HT composite electrode showed advantages in selective, quantitative, and more sensitive detection of Ag(+) ions. PMID:24730434

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

    PubMed

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

    2016-07-14

    The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm(2) V(-1) s(-1) and an on/off ratio of 10(6). We also established a model to quantitatively calculate the percentage of m-SWNTs on the substrate and this model shows a good match with the experimental data. Furthermore, our rational design also provides a new avenue for the growth of SWNTs with specific chirality and manipulated arrangement due to the difference of magnetic susceptibilities between different diameters, chiralities, and types. PMID:27315328

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

    PubMed Central

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

    2014-01-01

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

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

    SciTech Connect

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

    2012-03-15

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

  14. Toxicological Profiling of Highly Purified Metallic and Semiconducting Single-Walled Carbon Nanotubes in the Rodent Lung and E. coli.

    PubMed

    Wang, Xiang; Mansukhani, Nikhita D; Guiney, Linda M; Lee, Jae-Hyeok; Li, Ruibin; Sun, Bingbing; Liao, Yu-Pei; Chang, Chong Hyun; Ji, Zhaoxia; Xia, Tian; Hersam, Mark C; Nel, André E

    2016-06-28

    The electronic properties of single-walled carbon nanotubes (SWCNTs) are potentially useful for electronics, optics, and sensing applications. Depending on the chirality and diameter, individual SWCNTs can be classified as semiconducting (S-SWCNT) or metallic (M-SWCNT). From a biological perspective, the hazard profiling of purified metallic versus semiconducting SWCNTs has been pursued only in bacteria, with the conclusion that aggregated M-SWCNTs are more damaging to bacterial membranes than S-SWCNTs. However, no comparative studies have been performed in a mammalian system, where most toxicity studies have been undertaken using relatively crude SWCNTs that include a M:S mix at 1:2 ratio. In order to compare the toxicological impact of SWCNTs sorted to enrich them for each of the chirality on pulmonary cells and the intact lung, we used density gradient ultracentrifugation and extensive rinsing to prepare S- and M-SWCNTs that are >98% purified. In vitro screening showed that both tube variants trigger similar amounts of interleukin 1β (IL-1β) and transforming growth factor (TGF-β1) production in THP-1 and BEAS-2B cells, without cytotoxicity. Oropharyngeal aspiration confirmed that both SWCNT variants induce comparable fibrotic effects in the lung and abundance of IL-1β and TGF-β1 release in the bronchoalveolar lavage fluid. There was also no change in the morphology, membrane integrity, and viability of E. coli, in contradistinction to the previously published effects of aggregated tubes on the bacterial membrane. Collectively, these data indicate that the electronic properties and chirality do not independently impact SWCNT toxicological impact in the lung, which is of significance to the safety assessment and incremental use of purified tubes by industry. PMID:27159184

  15. Cutting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ziegler, Kirk J.; Gu, Zhenning; Shaver, Jonah; Chen, Zheyi; Flor, Erica L.; Schmidt, Daniel J.; Chan, Candace; Hauge, Robert H.; Smalley, Richard E.

    2005-07-01

    A two-step process is utilized for cutting single-walled carbon nanotubes (SWNTs). The first step requires the breakage of carbon-carbon bonds in the lattice while the second step is aimed at etching at these damage sites to create short, cut nanotubes. To achieve monodisperse lengths from any cutting strategy requires control of both steps. Room-temperature piranha and ammonium persulfate solutions have shown the ability to exploit the damage sites and etch SWNTs in a controlled manner. Despite the aggressive nature of these oxidizing solutions, the etch rate for SWNTs is relatively slow and almost no new sidewall damage is introduced. Carbon-carbon bond breakage can be introduced through fluorination to ~C2F, and subsequent etching using piranha solutions has been shown to be very effective in cutting nanotubes. The final average length of the nanotubes is approximately 100 nm with carbon yields as high as 70-80%.

  16. Chromatographic size separation of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    The efficient purification of single-wall carbon nanotubes (SWNTs) is reported. Carbon nanospheres, metal particles, and amorphous carbon could be successfully removed by size exclusion chromatography (SEC) applied to surfactant stabilised dispersions of SWNT raw material. In addition, length separation of the tubes was achieved. The SWNTs obtained can be adsorbed in high densities onto chemically modified substrates. As determined by AFM investigations, the purified material consists of about equal fractions of both individual SWNTS and ropes of SWNTs.

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

    NASA Astrophysics Data System (ADS)

    Ashour, Rakan F.

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

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

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

    SciTech Connect

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

    2013-03-01

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

  20. Noise characteristics of single-walled carbon nanotube network transistors

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

    2008-07-01

    The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors.

  1. Noise characteristics of single-walled carbon nanotube network transistors.

    PubMed

    Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

    2008-07-16

    The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors. PMID:21828739

  2. Single Walled Carbon Nanotube/Silicon Heterojunctions

    NASA Astrophysics Data System (ADS)

    Wu, Zhuangchun

    2005-11-01

    Characterization of the electrical heterojunction between single walled carbon nanotubes (SWNTs) and semiconductors is important for an array of potential applications. Thin, homogeneous, transparent, films of 100% SWNTs exhibiting good electrical conductivity [1] have already been demonstrated as the hole injection electrode in GaN light emitting diodes [2]. The simultaneous transparency and high electrical conductivity of these films makes them similarly promising for the light transmissive electrode in photovoltaic devices. SWNTs have moreover long been proposed as on-chip, device interconnects. To understand the electrical coupling between the nanotubes and semiconductors, likely to have relevance in such devices, we have begun a systematic exploration of the electrical properties of SWNT/silicon hetrojunctions. We will discuss findings as well as a novel test method made possible by the unique morphology of the nanotubes. 1. Z. Wu, Z. Chen, X. Du, J. M. Logan, J. Sippel, M. Nikolou, K. Kamaras, J. R. Reynolds, D. B. Tanner, A. F. Hebard, A. G. Rinzler, Science 305, 1273 (2004) 2. K. Lee, Z. Wu, Z. Chen, F. Ren, S. J. Pearton, A. G. Rinzler, Nano Lett. 4, 911 (2004)

  3. Improvements in Production of Single-Walled Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Balzano, Leandro; Resasco, Daniel E.

    2009-01-01

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

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

    SciTech Connect

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B. (Inventor)

    2013-01-01

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

  7. Determination of the metallic/semiconducting ratio in bulk single-wall carbon nanotube samples by cobalt porphyrin probe electron paramagnetic resonance spectroscopy.

    PubMed

    Cambré, Sofie; Wenseleers, Wim; Goovaerts, Etienne; Resasco, Daniel E

    2010-11-23

    A simple and quantitative, self-calibrating spectroscopic technique for the determination of the ratio of metallic to semiconducting single-wall carbon nanotubes (SWCNTs) in a bulk sample is presented. The technique is based on the measurement of the electron paramagnetic resonance (EPR) spectrum of the SWCNT sample to which cobalt(II)octaethylporphyrin (CoOEP) probe molecules have been added. This yields signals from both CoOEP molecules on metallic and on semiconducting tubes, which are easily distinguished and accurately characterized in this work. By applying this technique to a variety of SWCNT samples produced by different synthesis methods, it is shown that these signals for metallic and semiconducting tubes are independent of other factors such as tube length, defect density, and diameter, allowing the intensities of both signals for arbitrary samples to be retrieved by a straightforward least-squares regression. The technique is self-calibrating in that the EPR intensity can be directly related to the number of spins (number of CoOEP probe molecules), and as the adsorption of the CoOEP molecules is itself found to be unbiased toward metallic or semiconducting tubes, the measured intensities can be directly related to the mass percentage of metallic and semiconducting tubes in the bulk SWCNT sample. With the use of this method it was found that for some samples the metallic/semiconducting ratios strongly differed from the usual 1:2 ratio. PMID:20958073

  8. Resonance Raman Spectroscopy of Armchair Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Haroz, Erik; Rice, William; Lu, Benjamin; Hauge, Robert; Magana, Donny; Doorn, Stephen; Nikolaev, Pasha; Arepalli, Sivaram; Kono, Junichiro

    2009-03-01

    We performed resonance Raman spectroscopy studies of metallic single-walled carbon nanotubes (SWNTs), including armchair SWNTs from (6,6) through (10,10). The measurements were carried out with excitation of 440-850 nm on aqueous ensemble samples of SWNTs enriched in metallic species. From this, we generated Raman excitation profiles (REPs) of the radial breathing mode and compare the REPs of armchairs and other metallic species. Additionally, we measured REPs of the G-band mode and observed how the Breit-Wigner-Fano line shape of the G^- peak evolves in peak position, width and intensity relative to the G^+ peak as different metallic nanotubes are excited. By combining these studies with absorption and photoluminescence excitation spectroscopy studies, we present a comprehensive examination of the optical signatures of metallic SWNTs.

  9. Effect of selectively intercalated polyiodide on the electric transports of metallic- and semiconducting-enriched single-wall carbon nanotube networks

    NASA Astrophysics Data System (ADS)

    Fujimori, Toshihiko; Urita, Koki

    2016-06-01

    We report the selective intercalation of polyiodide chains (I5-) inside the interstitial sites of single-wall carbon nanotube (SWCNT) bundles of which internal sites are pre-encapsulated with monatomic sulfur chains. By using metallic- and semiconducting-enriched SWCNTs with diameter of ˜1 nm, our direct-current electric transport measurements reveal that the I5- intercalation on the metallic- and semiconducting-enriched SWCNT networks exhibits an opposite trend on the temperature dependence of the electric resistance at cryogenic temperature. Based on our analysis using the fluctuation-induced tunneling conduction model, the intercalation of I5- chains into the semiconducting-SWCNTs leads to the increase in energy barriers required for tunneling processes. Since the charge transfer is negligible between I5- chains and the semiconducting-SWCNTs, the main effect of the intercalated I5- on the semiconducting-SWCNTs is to behave as a scattering center below 50 K. In contrast to the semiconducting-SWCNTs, the intercalation of I5- chains into the metallic-SWCNTs results in the suppression of tunneling barriers due to the charge transfer interaction. The energy barrier is further reduced by the encapsulation of I5- chains inside the metallic-SWCNT, implying that the doping effect could be more effectively enhanced by the interaction through the inner spaces of SWCNTs.

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

    NASA Astrophysics Data System (ADS)

    Kim, Sang Nyon

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

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

    NASA Astrophysics Data System (ADS)

    Li, Yan

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

  12. Metal-Organic Polymers Containing Discrete Single-Walled Nanotube as a Heterogeneous Catalyst for the Cycloaddition of Carbon Dioxide to Epoxides.

    PubMed

    Zhou, Zhen; He, Cheng; Xiu, Jinghai; Yang, Lu; Duan, Chunying

    2015-12-01

    The cycloaddition of carbon dioxide to epoxides to produce cyclic carbonates is quite promising and does not result in any side products. A discrete single-walled metal-organic nanotube was synthesized by incorporating a tetraphenyl-ethylene moiety as the four-point connected node. The assembled complex has a large cross-section, with an exterior wall diameter of 3.6 nm and an interior channel diameter of 2.1 nm. It features excellent activity toward the cycloaddition of carbon dioxide, with a turnover number of 17,500 per mole of catalyst and an initial turnover frequency as high as 1000 per mole of catalyst per hour. Only minimal decreases in the catalytic activity were observed after 70 h under identical reaction conditions, and a total turnover number as high as 35,000 was achieved. A simple comparison of relative porous MOFs suggested that the cross-section of the channels is an important factor influencing the transport of the substrates and products through the channel. PMID:26584402

  13. Center for Applications of Single-Walled Carbon Nanotubes

    SciTech Connect

    Resasco, Daniel E

    2008-02-21

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

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

    PubMed

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

    2016-02-23

    We have proposed and fabricated stable and repeatable, flexible, single-walled carbon nanotube (SWCNT) thin film transistor (TFT) complementary metal-oxide-semiconductor (CMOS) integrated circuits based on a three-dimensional (3D) structure. Two layers of SWCNT-TFT devices were stacked, where one layer served as n-type devices and the other one served as p-type devices. On the basis of this method, it is able to save at least half of the area required to construct an inverter and make large-scale and high-density integrated CMOS circuits easier to design and manufacture. The 3D flexible CMOS inverter gain can be as high as 40, and the total noise margin is more than 95%. Moreover, the input and output voltage of the inverter are exactly matched for cascading. 3D flexible CMOS NOR, NAND logic gates, and 15-stage ring oscillators were fabricated on PI substrates with high performance as well. Stable electrical properties of these circuits can be obtained with bending radii as small as 3.16 mm, which shows that such a 3D structure is a reliable architecture and suitable for carbon nanotube electrical applications in complex flexible and wearable electronic devices. PMID:26768020

  15. Individual single-wall carbon nanotubes as quantum wires

    NASA Astrophysics Data System (ADS)

    Tans, Sander J.; Devoret, Michel H.; Dai, Hongjie; Thess, Andreas; Smalley, Richard E.; Geerligs, L. J.; Dekker, Cees

    1997-04-01

    Carbon nanotubes have been regarded since their discovery1 as potential molecular quantum wires. In the case of multi-wall nanotubes, where many tubes are arranged in a coaxial fashion, the electrical properties of individual tubes have been shown to vary strongly from tube to tube2,3, and to be characterized by disorder and localization4. Single-wall nanotubes5,6 (SWNTs) have recently been obtained with high yields and structural uniformity7. Particular varieties of these highly symmetric structures have been predicted to be metallic, with electrical conduction occurring through only two electronic modes8-10. Because of the structural symmetry and stiffness of SWNTs, their molecular wavefunctions may extend over the entire tube. Here we report electrical transport measurements on individual single-wall nanotubes that confirm these theoretical predictions. We find that SWNTs indeed act as genuine quantum wires. Electrical conduction seems to occur through well separated, discrete electron states that are quantum-mechanically coherent over long distance, that is at least from contact to contact (140nm). Data in a magnetic field indicate shifting of these states due to the Zeeman effect.

  16. Diameter-dependent solubility of single-walled carbon nanotubes.

    PubMed

    Duque, Juan G; Parra-Vasquez, A Nicholas G; Behabtu, Natnael; Green, Micah J; Higginbotham, Amanda L; Price, B Katherine; Leonard, Ashley D; Schmidt, Howard K; Lounis, Brahim; Tour, James M; Doorn, Stephen K; Cognet, Laurent; Pasquali, Matteo

    2010-06-22

    We study the solubility and dispersibility of as-produced and purified HiPco single-walled carbon nanotubes (SWNTs). Variation in specific operating conditions of the HiPco process are found to lead to significant differences in the respective SWNT solubilities in oleum and surfactant suspensions. The diameter distributions of SWNTs dispersed in surfactant solutions are batch-dependent, as evidenced by luminescence and Raman spectroscopies, but are identical for metallic and semiconducting SWNTs within a batch. We thus find that small diameter SWNTs disperse at higher concentration in aqueous surfactants and dissolve at higher concentration in oleum than do large-diameter SWNTs. These results highlight the importance of controlling SWNT synthesis methods in order to optimize processes dependent on solubility, including macroscopic processing such as fiber spinning, material reinforcement, and films production, as well as for fundamental research in type selective chemistry, optoelectronics, and nanophotonics. PMID:20521799

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

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram

    2004-01-01

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

  18. Single-Wall Carbon Nanotubes as Transparent Electrodes for Photovoltaics

    SciTech Connect

    Weeks, C.; Peltola, J.; Levitsky, I.; Glatkowski, P.; van de Lagemaat, J.; Rumbles, G.; Barnes, T.; Coutts, T.

    2006-01-01

    Transparent and electrically conductive coatings and films have a variety of uses in the fast-growing field of optoelectronic applications. Transparent electrodes typically include semiconductive metal oxides such as indium tin oxide (ITO), and conducting polymers such as poly(3,4-ethylenedioxythiophene), doped and stabilized with poly(styrenesulfonate) (PEDOT/PSS). In recent years, Eikos, Inc. has conceived and developed technologies to deliver novel alternatives using single-wall carbon nanotubes (SWNT). These technologies offer products having a broad range of conductivity, excellent transparency, neutral color tone, good adhesion, abrasion resistance as well as mechanical robustness. Additional benefits include ease of ambient processing and patterning capability. This paper reports our recent findings on achieving 2.6% and 1.4% efficiencies on nonoptimized organic photovoltaic cells employing SWNT as a transparent electrode.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  20. Purification Procedures for Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  1. Electrical characterization of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

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

    SciTech Connect

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

    2011-01-25

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

  4. Ion adsorption mechanism of bundled single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yoshida, Y.; Tsutsui, M.; Al-zubaidi, A.; Ishii, Y.; Kawasaki, S.

    2016-07-01

    In order to elucidate ion adsorption mechanism of bundled single-walled carbon nanotubes (SWCNTs), in situ synchrotron XRD measurements of SWCNT electrode in alkali halide aqueous electrolyte at several applied potentials were performed. It was found that the surface inside SWCNT is the important ion adsorption site.

  5. A Computational Experiment on Single-Walled Carbon Nanotubes

    ERIC Educational Resources Information Center

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

    2013-01-01

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

  6. Thermogravimetric Analysis of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivram; Nikolaev, Pavel; Gorelik, Olga

    2010-01-01

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

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

    PubMed

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

    2014-04-01

    Single-stranded DNA (ss-DNA) oligomers (dA20, d[(C3TA2)3C3] or dT20) are able to disperse single-walled carbon nanotubes (SWNTs) in water at pH 7 through non-covalent wrapping on the nanotube surface. At lower pH, an alteration of the DNA secondary structure leads to precipitation of the SWNTs from the dispersion. The structural change of dA20 takes place from the single-stranded to the A-motif form at pH 3.5 while in case of d[(C3TA2)3C3] the change occurs from the single-stranded to the i-motif form at pH 5. Due to this structural change, the DNA is no longer able to bind the nanotube and hence the SWNT precipitates from its well-dispersed state. However, this could be reversed on restoring the pH to 7, where the DNA again relaxes in the single-stranded form. In this way the dispersion and precipitation process could be repeated over and over again. Variable temperature UV-Vis-NIR and CD spectroscopy studies showed that the DNA-SWNT complexes were thermally stable even at ∼90 °C at pH 7. Broadband NIR laser (1064 nm) irradiation also demonstrated the stability of the DNA-SWNT complex against local heating introduced through excitation of the carbon nanotubes. Electrophoretic mobility shift assay confirmed the formation of a stable DNA-SWNT complex at pH 7 and also the generation of DNA secondary structures (A/i-motif) upon acidification. The interactions of ss-DNA with SWNTs cause debundling of the nanotubes from its assembly. Selective affinity of the semiconducting SWNTs towards DNA than the metallic ones enables separation of the two as evident from spectroscopic as well as electrical conductivity studies. PMID:24569668

  8. Directed Assembly of Single Wall Carbon Nanotube Field Effect Transistors.

    PubMed

    Penzo, Erika; Palma, Matteo; Chenet, Daniel A; Ao, Geyou; Zheng, Ming; Hone, James C; Wind, Shalom J

    2016-02-23

    The outstanding electronic properties of single wall carbon nanotubes (SWCNTs) have made them prime candidates for future nanoelectronics technologies. One of the main obstacles to the implementation of advanced SWCNT electronics to date is the inability to arrange them in a manner suitable for complex circuits. Directed assembly of SWCNT segments onto lithographically patterned and chemically functionalized substrates is a promising way to organize SWCNTs in topologies that are amenable to integration for advanced applications, but the placement and orientational control required have not yet been demonstrated. We have developed a technique for assembling length sorted and chirality monodisperse DNA-wrapped SWCNT segments on hydrophilic lines patterned on a passivated oxidized silicon substrate. Placement of individual SWCNT segments at predetermined locations was achieved with nanometer accuracy. Three terminal electronic devices, consisting of a single SWCNT segment placed either beneath or on top of metallic source/drain electrodes were fabricated. Devices made with semiconducting nanotubes behaved as typical p-type field effect transistors (FETs), whereas devices made with metallic nanotubes had a finite resistance with little or no gate modulation. This scalable, high resolution approach represents an important step forward toward the potential implementation of complex SWCNT devices and circuits. PMID:26807948

  9. Single-walled carbon nanotube based molecular switch tunnel junctions.

    PubMed

    Diehl, Michael R; Steuerman, David W; Tseng, Hsian-Rong; Vignon, Scott A; Star, Alexander; Celestre, Paul C; Stoddart, J Fraser; Heath, James R

    2003-12-15

    This article describes two-terminal molecular switch tunnel junctions (MSTJs) which incorporate a semiconducting, single-walled carbon nanotube (SWNT) as the bottom electrode. The nanotube interacts noncovalently with a monolayer of bistable, nondegenerate [2]catenane tetracations, self-organized by their supporting amphiphilic dimyristoylphosphatidyl anions which shield the mechanically switchable tetracations from a two-micrometer wide metallic top electrode. The resulting 0.002 micron 2 area tunnel junction addresses a nanometer wide row of approximately 2000 molecules. Active and remnant current-voltage measurements demonstrated that these devices can be reconfigurably switched and repeatedly cycled between high and low current states under ambient conditions. Control compounds, including a degenerate [2]catenane, were explored in support of the mechanical origin of the switching signature. These SWNT-based MSTJs operate like previously reported silicon-based MSTJs, but differently from similar devices incorporating bottom metal electrodes. The relevance of these results with respect to the choice of electrode materials for molecular electronics devices is discussed. PMID:14714382

  10. Chirality Characterization of Dispersed Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  11. Thermionic Emission of Single-Wall Carbon Nanotubes Measured

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  12. Structure of single-wall carbon nanotubes: a graphene helix.

    PubMed

    Lee, Jae-Kap; Lee, Sohyung; Kim, Jin-Gyu; Min, Bong-Ki; Kim, Yong-Il; Lee, Kyung-Il; An, Kay Hyeok; John, Phillip

    2014-08-27

    Evidence is presented in this paper that certain single-wall carbon nanotubes are not seamless tubes, but rather adopt a graphene helix resulting from the spiral growth of a nano-graphene ribbon. The residual traces of the helices are confirmed by high-resolution transmission electron microscopy and atomic force microscopy. The analysis also shows that the tubular graphene material may exhibit a unique armchair structure and the chirality is not a necessary condition for the growth of carbon nanotubes. The description of the structure of the helical carbon nanomaterials is generalized using the plane indices of hexagonal space groups instead of using chiral vectors. It is also proposed that the growth model, via a graphene helix, results in a ubiquitous structure of single-wall carbon nanotubes. PMID:24838196

  13. Synthesis of Single-Wall Carbon Nanotubes from Diesel Soot

    NASA Astrophysics Data System (ADS)

    Uchida, Takashi; Ohashi, Ouji; Kawamoto, Hironori; Yoshimura, Hirofumi; Kobayashi, Ken-ichi; Tanimura, Makoto; Fujikawa, Naohiro; Nishimoto, Tetsuro; Awata, Kazuhiko; Tachibana, Masaru; Kojima, Kenichi

    2006-10-01

    We show that diesel soot can be recycled as a carbon source for the synthesis of single-wall carbon nanotubes (SWNTs). The synthesis of SWNTs was carried out by the laser vaporization of diesel soot. The presence of SWNTs was confirmed by Raman spectroscopy and transmission electron microscopy. SWNTs produced in this way should provide economic benefits and also contribute to a cleaner environment.

  14. Production of single-walled carbon nanotube grids

    DOEpatents

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

    2013-12-03

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

  15. Spectroscopy-Based Characterization of Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

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

    SciTech Connect

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

    2007-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  18. Quantitative optical imaging of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Herman, Lihong H.

    The development and application of optical imaging tools and probing techniques have been the subject of exciting research. These tools and techniques allow for non-invasive, simple sample preparation and relatively fast measurement of electronic and optical properties. They also provided crucial information on optoelectronic device application and development. As the field of nanostructure research emerged, they were modified and employed to understand various properties of these structures at the diffraction limit of light. Carbon nanotubes, up to hundreds of micrometers long and several nanometers thin, are perfect for testing and demonstrating newly-developed optical measurement platforms for individual nanostructures, due to their heterogeneous nature. By employing two quantitative imaging techniques, wide-field on-chip Rayleigh scattering spectroscopy and spatial modulation confocal absorption microscopy, we investigate the optical properties of single-walled carbon nanotubes. These techniques allow us to obtain the Rayleigh scattering intensity, absolute absorption cross section, spatial resolution, and spectral information of single-walled carbon nanotubes. By probing the optical resonance of hundreds of single-walled carbon nanotubes in a single measurement, the first technique utilizes Rayleigh scattering mechanism to obtain the chirality of carbon nanotubes. The second technique, by using high numerical aperture oil immersion objective lenses, we measure the absolute absorption cross section of a single-walled carbon nanotube. Combining all the quantitative values obtained from these techniques, we observe various interesting and recently discovered physical behaviors, such as long range optical coupling and universal optical conductivity on resonance, and demonstrate the possibility of accurate quantitative absorption measurement for individual structures at nanometer scale.

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

    NASA Astrophysics Data System (ADS)

    Ryu, Koungmin

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

  20. Fabrication of stretchable single-walled carbon nanotube logic devices.

    PubMed

    Yoon, Jangyeol; Shin, Gunchul; Kim, Joonsung; Moon, Young Sun; Lee, Seung-Jung; Zi, Goangseup; Ha, Jeong Sook

    2014-07-23

    The fabrication of a stretchable single-walled carbon nanotube (SWCNT) complementary metal oxide semiconductor (CMOS) inverter array and ring oscillators is reported. The SWCNT CMOS inverter exhibits static voltage transfer characteristics with a maximum gain of 8.9 at a supply voltage of 5 V. The fabricated devices show stable electrical performance under the maximum strain of 30% via forming wavy configurations. In addition, the 3-stage ring oscillator demonstrates a stable oscillator frequency of ∼3.5 kHz at a supply voltage of 10 V and the oscillating waveforms are maintained without any distortion under cycles of pre-strain and release. The strains applied to the device upon deformation are also analyzed by using the classical lamination theory, estimating the local strain of less than 0.6% in the SWCNT channel and Pd electrode regions which is small enough to keep the device performance stable under the pre-strain up to 30%. This work demonstrates the potential application of stretchable SWCNT logic circuit devices in future wearable electronics. PMID:24700788

  1. Sorting centimetre-long single-walled carbon nanotubes.

    PubMed

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

    2016-01-01

    While several approaches have been developed for sorting metallic (m) or semiconducting (s) single-walled carbon nanotubes (SWCNTs), the length of SWCNTs is limited within a micrometer, which restricts excellent electrical performances of SWCNTs for macro-scale applications. Here, we demonstrate a simple sorting method of centimetre-long aligned m- and s-SWCNTs. Ni particles were selectively and uniformly coated along the 1-cm-long m-SWCNTs by applying positive gate bias during electrochemical deposition with continuous electrolyte injection. To sort s-SWCNTs, the Ni coating was oxidized to form insulator outer for blocking of current flow through inner m-SWCNTs. Sorting of m-SWCNTs were demonstrated by selective etching of s-SWCNTs via oxygen plasma, while the protected m-SWCNTs by Ni coating remained intact. The series of source-drain pairs were patterned along the 1-cm-long sorted SWCNTs, which confirmed high on/off ratio of 10(4)-10(8) for s-SWCNTs and nearly 1 for m-SWCNTs. PMID:27476909

  2. Single-wall carbon nanotubes and peapods investigated by EPR.

    PubMed

    Corzilius, B; Dinse, K-P; Hata, K

    2007-12-14

    Single-wall carbon nanotubes (SWNT) prepared by the "super growth" method developed recently exhibit electron paramagnetic resonance (EPR) signals, which can be attributed to itinerant spins. EPR results indicate very low defect and catalyst concentrations in this superior material. Under these conditions EPR can be used to study details of charge transport properties over a wide temperature range, although the material is still very "heterogeneous" with respect to tube diameter and chirality. Non-resonant microwave absorption in the temperature range below 20 K is indicative for the opening of a small gap at the Fermi energy for tubes of metallic character, which is indicative for a transition into a superconducting state. Using SWNT filled partially with an endohedral spin probe like N@C(60), such "peapods" can be investigated "from the inside". Continuous-wave (cw) and pulsed EPR was used to investigate localization dynamics within the tubes or to check for interaction with itinerant electrons. Using SWNT grown by different methods, the dominant influence of tube diameter on fullerene dynamics was revealed by temperature dependent pulsed EPR experiments. These differences can be correlated with the interactions between the endohedral observer spin and spins on the SWNT. PMID:18167581

  3. Sorting centimetre-long single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  4. Sorting centimetre-long single-walled carbon nanotubes

    PubMed Central

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

    2016-01-01

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

  5. Single-Walled Carbon-Nanotubes-Based Organic Memory Structures.

    PubMed

    Fakher, Sundes; Nejm, Razan; Ayesh, Ahmad; Al-Ghaferi, Amal; Zeze, Dagou; Mabrook, Mohammed

    2016-01-01

    The electrical behaviour of organic memory structures, based on single-walled carbon-nanotubes (SWCNTs), metal-insulator-semiconductor (MIS) and thin film transistor (TFT) structures, using poly(methyl methacrylate) (PMMA) as the gate dielectric, are reported. The drain and source electrodes were fabricated by evaporating 50 nm gold, and the gate electrode was made from 50 nm-evaporated aluminium on a clean glass substrate. Thin films of SWCNTs, embedded within the insulating layer, were used as the floating gate. SWCNTs-based memory devices exhibited clear hysteresis in their electrical characteristics (capacitance-voltage (C-V) for MIS structures, as well as output and transfer characteristics for transistors). Both structures were shown to produce reliable and large memory windows by virtue of high capacity and reduced charge leakage. The hysteresis in the output and transfer characteristics, the shifts in the threshold voltage of the transfer characteristics, and the flat-band voltage shift in the MIS structures were attributed to the charging and discharging of the SWCNTs floating gate. Under an appropriate gate bias (1 s pulses), the floating gate is charged and discharged, resulting in significant threshold voltage shifts. Pulses as low as 1 V resulted in clear write and erase states. PMID:27598112

  6. Reinforcement of Epoxies Using Single Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Krishnamoorti, Ramanan; Sharma, Jitendra; Chatterjee, Tirtha

    2008-03-01

    The reinforcement of bisphenol-A and bisphenol-F epoxies using single walled carbon nanotubes has been approached experimentally by understanding the nature of interactions between the matrices and nanotubes. Unassisted dispersions of single walled carbon nanotubes in epoxies were studied by a combination of radiation scattering (elastic small angle scattering and inelastic scattering), DSC based glass transition determination, melt rheology and solid-state mechanical testing in order to understand and correlate changes in local and global dynamics to the tailoring of composite mechanical properties. Significant changes in the glass transition temperature of the matrix can successfully account for changes in the viscoelastic properties of the epoxy dispersions for concentrations below the percolation threshold, while above the percolation threshold the network superstructure formed by the nanotubes controls the viscoelastic properties.

  7. Reversible separation of single-walled carbon nanotubes in bundles

    SciTech Connect

    Sahoo, Sangeeta; Lastella, Sarah; Maranganti, Ravi; Sharma, Pradeep; Mallick, Govind; Karna, Shashi; Ajayan, Pulickel M.

    2008-08-25

    We show that electrostatic charging of nanotubes and the consequent repulsion can lead to reversible separation of individual single-walled carbon nanotubes in bundles. Low-energy electron beam irradiation leads to this completely reversible phenomenon. A simple semianalytical model is used to explain the observed separation mechanism. The reversibility of the separation process is attributed to discharging and thermal-fluctuation induced motion of the nanotubes in ambient air. Further, the separation impacts the electrical conductance of small nanotube bundled devices.

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

    NASA Technical Reports Server (NTRS)

    Lebron-COlon, Marisabel; Meador, Michael A.

    2006-01-01

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

  9. Titanium dioxide, single-walled carbon nanotube composites

    DOEpatents

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

    2015-07-14

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

  10. Dynamic terahertz polarization in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Xu, X. L.; Parkinson, P.; Chuang, K.-C.; Johnston, M. B.; Nicholas, R. J.; Herz, L. M.

    2010-08-01

    We have investigated the anisotropic dynamic dielectric response of aligned and well-isolated single-walled carbon nanotubes using optical-pump terahertz (THz)-probe techniques. The polarization anisotropy measurements demonstrate that the THz radiation interacts only with radiation polarized parallel to the nanotubes which have been selectively excited by a polarized pump pulse thus allowing controlled THz polarization to be achieved from unaligned nanotubes.

  11. Band gap opening and semiconductor-metal phase transition in (n, n) single-walled carbon nanotubes with distinctive boron-nitrogen line defect.

    PubMed

    Qiu, Ming; Xie, Yuanyuan; Gao, Xianfeng; Li, Jianyang; Deng, Yelin; Guan, Dongsheng; Ma, Lulu; Yuan, Chris

    2016-02-14

    Band gap opening and modulating are critical in dictating the functionalities of single walled carbon nanotubes (SWCNTs) in a broad array of nano-devices. Using first-principles density functional theory calculations, a class of semiconducting armchair SWCNTs with a distinctive BN line defect are studied, showing a super capacity to open the band gap of (4, 4) SWCNT to as large as 0.86 eV, while the opened band gap are found decreasing with the increasing diameters of SWCNTs. The opened band gap of SWCNTs can also be successfully modulated through both mechanical and electrical approaches by applying compressive uniaxial strain and electric field. This study provides novel insights into the large band gap opening and modulating of SWCNTs and could be useful in facilitating future applications of SWCNTs in electronic, optical and thermoelectric devices. PMID:26794602

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

    PubMed Central

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

    2016-01-01

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

  13. Self-assembling Functionalized Single-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Gao, Yan

    Single-walled carbon nanotubes (SWCNTs) are promising bottom-up building materials due to their superior properties. However, the lack of an effective method to arrange large quantities of SWCNTs poses an obstacle toward their applications. Existing studies to functionalize, disperse, position, and assemble SWCNTs provide a broad understandings regarding SWCNTs behavior, especially in aqueous electrolyte solution. Inspired by ionic polymer metal composite (IPMC) materials, this dissertation envisions fabrication of orderly SWCNTs network structure via their ionic clustering-mediated self-assembly. SWCNTs tend to bundle together due to inter-nanotube VDW attractions, which increase with nanotube length. The author seeks short SWCNTs with long chain molecules bearing ionic termini to facilitate debundling and self-assembly in aqueous electrolyte solution through end-clustering. First, a simple model was applied based on essential physical factors. The results indicated that SWCNTs must be shorter than ˜100 nm to achieve stable network structures. Experiments were then carried out based upon the results. Short SWCNTs (50-100 nm) were end-functionalized with hexaethylene glycol (HEG) linkers bearing terminal carboxylate anions. Both 2D and 3D network structures were observed after placing the functionalized SWCNTs in aqueous electrolyte (sodium ion). The network structures were characterized by microscopic and spectroscopic methods. A novel approach was applied via electron tomography to study the 3D structures of SWCNTs structure in aqueous electrolyte. Free energy analysis of the SWCNTs network structure was implemented with the assistance of both analytical tools and molecular simulations. The results indicate that, when a cluster is formed by three functionalized SWCNTs ends, the resulting network structure is most stable. Indeed, 72% of the clusters/joints were formed by three nanotubes, as observed in experiments. Finally, Monte Carlo simulations of coarse

  14. Optical Characterization and Applications of Single Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Strano, Michael S.

    2005-03-01

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

  15. 40 CFR 721.10156 - Single-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  16. 40 CFR 721.10156 - Single-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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

  17. 40 CFR 721.10156 - Single-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  18. 40 CFR 721.10156 - Single-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  19. Key roles of carbon solubility in single-walled carbon nanotube nucleation and growth

    NASA Astrophysics Data System (ADS)

    He, Maoshuai; Amara, Hakim; Jiang, Hua; Hassinen, Jukka; Bichara, Christophe; Ras, Robin H. A.; Lehtonen, Juha; Kauppinen, Esko I.; Loiseau, Annick

    2015-11-01

    Elucidating the roles played by carbon solubility in catalyst nanoparticles is required to better understand the growth mechanisms of single-walled carbon nanotubes (SWNTs). Here, we highlight that controlling the level of dissolved carbon is of key importance to enable nucleation and growth. We first performed tight binding based atomistic computer simulations to study carbon incorporation in metal nanoparticles with low solubilities. For such metals, carbon incorporation strongly depends on their structures (face centered cubic or icosahedral), leading to different amounts of carbon close to the nanoparticle surface. Following this idea, we then show experimentally that Au nanoparticles effectively catalyze SWNT growth when in a face centered cubic structure, and fail to do so when icosahedral. Both approaches emphasize that the presence of subsurface carbon in the nanoparticles is necessary to enable the cap lift-off, making the nucleation of SWNTs possible.Elucidating the roles played by carbon solubility in catalyst nanoparticles is required to better understand the growth mechanisms of single-walled carbon nanotubes (SWNTs). Here, we highlight that controlling the level of dissolved carbon is of key importance to enable nucleation and growth. We first performed tight binding based atomistic computer simulations to study carbon incorporation in metal nanoparticles with low solubilities. For such metals, carbon incorporation strongly depends on their structures (face centered cubic or icosahedral), leading to different amounts of carbon close to the nanoparticle surface. Following this idea, we then show experimentally that Au nanoparticles effectively catalyze SWNT growth when in a face centered cubic structure, and fail to do so when icosahedral. Both approaches emphasize that the presence of subsurface carbon in the nanoparticles is necessary to enable the cap lift-off, making the nucleation of SWNTs possible. Electronic supplementary information (ESI

  20. Single-Walled Carbon Nanotube/PMMA Composites

    NASA Astrophysics Data System (ADS)

    Du, Fangming; Fisher, John; Winey, Karen

    2003-03-01

    Single-walled carbon nanotubes (SWNTs) have demonstrated unique mechanical, thermal and electrical properties. Similar properties are expected for polymer/SWNT nanocomposites. A new processing method has been used to produce PMMA/SWNT composites, which provides better dispersion of SWNT in the polymer matrix. Optical microscopy of the samples show improved dispersion of SWNT in the PMMA matrix, which is the key factor of the composite performance. Aligned and unaligned composite samples have been made for both purified SWNT and functionalized SWNT with different SWNT loadings. The tensile, thermal conductivity, and electroconductivity measurements of these samples will be performed.

  1. Phonon Density of States of Single-Wall Carbon Nanotubes

    SciTech Connect

    Rols, S.; Benes, Z.; Anglaret, E.; Sauvajol, J. L.; Papanek, P.; Fischer, J. E.; Coddens, G.; Schober, H.; Dianoux, A. J.

    2000-12-11

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

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

    NASA Astrophysics Data System (ADS)

    Ellison, Mark D.; Chorney, Matthew

    2016-10-01

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

  3. Charge-induced strains in single-walled carbon nanotubes.

    PubMed

    Li, Chun-Yu; Chou, Tsu-Wei

    2006-09-28

    This paper investigates the electromechanical coupling in single-walled carbon nanotubes. In the model system, the extra electric charge of the nanotube is assumed to be uniformly distributed on carbon atoms. The electrostatic interactions between charged carbon atoms are calculated using the Coulomb law. The deformation of the charged nanotube is obtained by using the molecular structural mechanics method and considering the electrostatic interactions as an external loading acting on carbon atoms. The axial strain is found to be a symmetric function of applied charge, and our predictions are in very good agreement with those from ab initio calculations. The present results indicate that the nanotube aspect ratio has a strong effect on the axial strain when the ratio is less than 10 and the general trend is that the strain increases with the aspect ratio. The peak axial and radial strains occur at nanotube diameters of around 1.2-1.5 nm. PMID:21727586

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

    USGS Publications Warehouse

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

    2004-01-01

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

  5. Single Wall Carbon Nano Tube Films and Coatings

    NASA Astrophysics Data System (ADS)

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

    2002-03-01

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

  6. Storage of Hydrogen in Single-Walled Carbon Nanotubes

    SciTech Connect

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

    1997-03-27

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

  7. Scanning gate microscopy of electronic inhomogeneities in single-walled carbon nanotube (SWCNT) devices

    NASA Astrophysics Data System (ADS)

    Hunt, Steven R.; Collins, Phillip G.

    2010-03-01

    The electronic properties of graphitic carbon devices are primarily determined by the contact metal and the carbon band structure. However, inhomogeneities such as substrate imperfections, surface defects, and mobile contaminants also contribute and can lead to transistor-like behaviors. We experimentally investigate this phenomena in the 1-D limit using metallic single-walled carbon nanotubes (SWCNTs) before and after the electrochemical creation of sidewall defects. While scanning gate microscopy readily identifies the defect sites, the energy-dependence of the technique allows quantitative analysis of the defects and discrimination of different defect types. This research is partly supported by the NSF (DMR 08-xxxx).

  8. Radiation Protection Using Single-Wall Carbon Nanotube Derivatives

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  9. Magnetic Fractionation and Alignment of Single Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Islam, M. F.; Milkie, D. E.; Yodh, A. G.; Kikkawa, J. M.

    2004-03-01

    We study mechanisms of single wall carbon nanotube (SWNT) alignment in a magnetic field. Through magnetic fractionation, we create SWNT suspensions with varying quantities of magnetic catalyst particles. The degree of tube alignment in magnetic fields up to 9 Tesla is quantified using polarized optical absorbance anisotropy. Continuous measurements of the nematic order parameter of these suspensions in variable magnetic fields provides a way to identify the origin of magnetic torques giving rise to nanotube alignment. Initial data suggests a transition from catalyst-driven to nanotube-anisotropy driven orientation as the catalyst fraction is reduced. We relate these results to observations of nanotube aggregation. This work has been supported by NSF through DMR-0203378, DMR-079909 and DGE-0221664, NASA through NAG8-2172, DARPA/ONR through N00014-01-1-0831, and SENS.

  10. Phonon sidebands of photoluminescence in single wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yu, Guili; Liang, Qifeng; Jia, Yonglei; Dong, Jinming

    2010-01-01

    The multiphonon-assisted photoluminescence (PL) of the single wall carbon nanotubes (SWNTs) have been studied by solving the Schrödinger equation, showing a set of phonon sidebands, both the Stokes and anti-Stokes lines, which are induced by the longitudinal optical phonon and radial breathing mode phonon. All the calculated results are in a good agreement with the recent experimental PL spectra of the SWNTs [F. Plentz, H. B. Ribeiro, A. Jorio, M. S. Strano, and M. A. Pimenta, Phys. Rev. Lett. 95, 247401 (2005)] and J. Lefebvre and P. Finnie, Phys. Rev. Lett. 98, 167406 (2007)]. In addition, it is very interesting to find in the calculated PL several additional phonon sidebands with rather weak intensities, which are caused by the exciton's coupling with two kinds of phonons, and expected to be observed in future experiments.

  11. Structural anisotropy of magnetically aligned single wall carbon nanotube films

    SciTech Connect

    Smith, B. W.; Benes, Z.; Luzzi, D. E.; Fischer, J. E.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

    2000-07-31

    Thick films of aligned single wall carbon nanotubes and ropes have been produced by filtration/deposition from suspension in strong magnetic fields. We measured mosaic distributions of rope orientations in the film plane, for samples of different thicknesses. For an {approx}1 {mu}m film the full width at half maximum (FWHM) derived from electron diffraction is 25 degree sign -28 degree sign . The FWHM of a thicker film ({approx}7 {mu}m) measured by x-ray diffraction is slightly broader, 35{+-}3 degree sign . Aligned films are denser than ordinary filter-deposited ones, and much denser than as-grown material. Optimization of the process is expected to yield smaller FWHMs and higher densities. (c) 2000 American Institute of Physics.

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

    PubMed Central

    Rodriguez, Kenneth R.; Nanney, Warren A.; A. Maddux, Cassandra J.; Martínez, Hernán L.

    2014-01-01

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

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

    SciTech Connect

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

    2014-12-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  15. Finely dispersed single-walled carbon nanotubes for polysaccharide hydrogels.

    PubMed

    Yan, Liang Yu; Chen, Hailan; Li, Peng; Kim, Dong-Hwan; Chan-Park, Mary B

    2012-09-26

    Here we demonstrate a polysaccharide hydrogel reinforced with finely dispersed single-walled carbon nanotubes (SWNTs) using biocompatible dispersants O-carboxymethylchitosan (OC) and chondroitin sulfate A (CS-A) as a structural support. Both of the dispersants can disperse SWNTs in aqueous solutions and hydrogel matrix as individual tubes or small bundles. Additionally, we have found that compressive modulus and strain of the hydrogels reinforced with SWNTs were enhanced as much as two times by the addition of a few weight percent of SWNTs. Moreover, the SWNT-incorporated hydrogels exhibited lower impedance and higher charge capacity than the alginate/dispersant hydrogel without SWNTs. The OC and the CS-A demonstrated much higher reinforcing enhancement than a commercially available dispersant, sodium dodecyl sulfate. Combined with the experimental data on the mechanical and electrical properties, the biocompatibility of OC and CS-A can provide the possibility of biomedical application of the SWNT-reinforced hydrogels. PMID:22909447

  16. Molecular Imaging with Single-Walled Carbon Nanotubes

    PubMed Central

    Hong, Hao; Gao, Ting; Cai, Weibo

    2011-01-01

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

  17. Single Wall Carbon Nanotube-polymer Solar Cells

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  18. Selective bundling of zigzag single-walled carbon nanotubes.

    PubMed

    Blum, Carolin; Stürzl, Ninette; Hennrich, Frank; Lebedkin, Sergei; Heeg, Sebastian; Dumlich, Heiko; Reich, Stephanie; Kappes, Manfred M

    2011-04-26

    A simple, high throughput fractionation procedure for aqueous/SDS (sodium dodecyl sulfate) suspensions of single-walled carbon nanotubes (SWNTs) is presented, which yields thin bundles of semiconducting-SWNTs with small chiral angles. To demonstrate this we show the photoluminescence signatures of nanotube suspensions that contain almost exclusively zigzag and near-zigzag tubes. Starting suspensions and resulting fractions were characterized using optical absorption, resonance Raman and photoluminescence spectroscopies as well as scanning force microscopy. Taken together with literature observations, our findings suggest that near zigzag edge tubes of similar diameters in a bundle are harder to separate from each other than for other chiral index combinations. We discuss the implications of these observations for SWNT growth and dispersion. PMID:21410134

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    SciTech Connect

    Rosati, Roberto; Rossi, Fausto; Dolcini, Fabrizio

    2015-06-15

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

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

    SciTech Connect

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

    2008-10-20

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

  2. Single-Wall Carbon Nanotube Anodes for Lithium Cells

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  3. 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.

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

    EPA Science Inventory

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

  5. MINIMAL INFLAMMOGENICITY OF PRISTINE SINGLE-WALL CARBON NANOTUBES

    PubMed Central

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

    2015-01-01

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

  6. Third Harmonic Generation from Aligned Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Morris, Darius T., Jr.

    Optical properties of single-wall carbon nanotubes (SWCNTs) have been extensively studied during the last decade, and much basic knowledge has been accumulated on how light emission, scattering, and absorption occur in the realm of linear optics. However, their nonlinear optical properties remain largely unexplored. Here, we have observed strong third harmonic generation from highly aligned SWCNTs with intense mid-infrared radiation. Through power dependent experiments, we have determined the absolute value of the third-order nonlinear optical susceptibility, chi(3), of our SWCNT film to be 6.92 x 10--12 esu, which is three orders of magnitude larger than that of the fused silica reference sample we used. Furthermore, through polarization-dependent third harmonic generation experiments, all the nonzero tensor elements of chi(3) have also been extracted. The contribution of the weaker tensor elements to the overall chi (3) signal has been calculated to be approximately 1/6 of that of the dominant c3z zzz component. These results open up new possibilities for application of carbon nanotubes in optoelectronics.

  7. Single-wall carbon nanotube chemical attachment at platinum electrodes

    NASA Astrophysics Data System (ADS)

    Rosario-Castro, Belinda I.; Contés-de-Jesús, Enid J.; Lebrón-Colón, Marisabel; Meador, Michael A.; Scibioh, M. Aulice; Cabrera, Carlos R.

    2010-11-01

    Self-assembled monolayer (SAM) techniques were used to adsorb 4-aminothiophenol (4-ATP) on platinum electrodes in order to obtain an amino-terminated SAM as the base for the chemical attachment of single-wall carbon nanotubes (SWCNTs). A physico-chemical, morphological and electrochemical characterizations of SWCNTs attached onto the modified Pt electrodes was done by using reflection-absorption infrared spectroscopy (RAIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and cyclic voltammetry (CV) techniques. The SWNTs/4-ATP/Pt surface had regions of small, medium, and large thickness of carbon nanotubes with heights of 100-200 nm, 700 nm to 1.5 μm, and 1.0-3.0 μm, respectively. Cyclic voltammetries (CVs) in sulfuric acid demonstrated that attachment of SWNTs on 4-ATP/Pt is markedly stable, even after 30 potential cycles. CV in ruthenium hexamine was similar to bare Pt electrodes, suggesting that SWNTs assembly is similar to a closely packed microelectrode array.

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

    SciTech Connect

    Gharbavi, K.; Badehian, H.

    2015-07-15

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

  9. Single-Walled Carbon Nanotube Transporter for Gene Delivery

    NASA Astrophysics Data System (ADS)

    Ke, Pu-Chun

    2005-03-01

    Recent studies have shown great promises in integrating nanomaterials in biomedicine. To explore the feasibility of using single-walled carbon nanotubes (SWNTs) as transporters for gene delivery, we have investigated the binding of SWNTs and RNA polymer poly(rU), and the diffusion and the translocation of the SWNT-poly(rU) complexes. Through single-molecule fluorescence imaging, we have found that the pi- stacking dominates the hydrophobic interactions between the carbon rings on tubes and the nitrogenous bases of RNA. Our diffusion study has further demonstrated the feasibility of tracking the motion of water soluble SWNT-poly(rU) complexes. The uptake of SWNT-poly(rU) by breast cancer cells MCF7 was observed using confocal scanning fluorescence microscopy. It was evident that the complexes could penetrate through cell membrane into cytoplasm and cell nucleus. Our cell culture, MTS assay, and radioisotope labeling showed the negligible cytotoxicity of surface modified SWNTs with RNA polymer and amino acids in cell growth medium. These studies have paved the way for gene transfection using SWNTs as transporters.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  11. Reinforced thermoplastic polyimide with dispersed functionalized single wall carbon nanotubes.

    PubMed

    Lebrón-Colón, Marisabel; Meador, Michael A; Gaier, James R; Solá, Francisco; Scheiman, Daniel A; McCorkle, Linda S

    2010-03-01

    Molecular pi-complexes were formed from pristine HiPCO single- wall carbon nanotubes (SWCNTs) and 1-pyrene- N-(4-N'-(5-norbornene-2,3-dicarboxyimido)phenyl butanamide, 1. Polyimide films were prepared with these complexes as well as uncomplexed SWCNTs and the effects of nanoadditive addition on mechanical, thermal, and electrical properties of these films were evaluated. Although these properties were enhanced by both nanoadditives, larger increases in tensile strength and thermal and electrical conductivities were obtained when the SWCNT/1 complexes were used. At a loading level of 5.5 wt %, the T(g) of the polyimide increased from 169 to 197 degrees C and the storage modulus increased 20-fold (from 142 to 3045 MPa). The addition of 3.5 wt % SWCNT/1 complexes increased the tensile strength of the polyimide from 61.4 to 129 MPa; higher loading levels led to embrittlement and lower tensile strengths. The electrical conductivities (DC surface) of the polyimides increased to 1 x 10(-4) Scm(-1) (SWCNT/1 complexes loading level of 9 wt %). Details of the preparation of these complexes and their effects on polyimide film properties are discussed. PMID:20356267

  12. Resonance Raman Optical Activity of Single Walled Chiral Carbon Nanotubes.

    PubMed

    Nagy, Péter R; Koltai, János; Surján, Péter R; Kürti, Jenő; Szabados, Ágnes

    2016-07-21

    Resonance (vibrational) Raman Optical Activity (ROA) spectra of six chiral single-walled carbon nanotubes (SWCNTs) are studied by theoretical means. Calculations are performed imposing line group symmetry. Polarizability tensors, computed at the π-electron level, are differentiated with respect to DFT normal modes to generate spectral intensities. This computational protocol yields a ROA spectrum in good agreement with the only experiment on SWCNT, available at present. In addition to the conventional periodic electric dipole operator we introduce magnetic dipole and electric quadrupole operators, suitable for conventional k-space calculations. Consequences of the complex nature of the wave function on the scattering cross section are discussed in detail. The resonance phenomenon is accounted for by the short time approximation. Involvement of fundamental vibrations in the region of the intermediate frequency modes is found to be more notable in ROA than in Raman spectra. Calculations indicate exceptionally strong resonance enhancement of SWCNT ROA signals. Resonance ROA profile of the (6,5) tube shows an interesting sign change that may be exploited experimentally for SWCNT identification. PMID:27315548

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

    NASA Astrophysics Data System (ADS)

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

    1997-03-01

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

  14. Low-temperature growth of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kim, S.-M.; Zhang, Y.; Wang, X.; Teo, K. B. K.; Gangloff, L.; Milne, W. I.; Wu, J.; Eastman, M.; Jiao, J.

    2007-12-01

    The low-temperature synthesis (450-560 °C) of single-walled carbon nanotubes (SWCNTs) on a triple-layered catalyst, Al/Fe/Mo, was performed using aromatic hydrocarbon radicals which were produced from the pyrolysis of C2H2. Two approaches were used; in the first, these hydrocarbon radicals were produced using a high-temperature heater (830 °C), but the substrate where the SWCNTs were grown was placed on a thermal insulator above it such that the substrate was at a much lower temperature. In the second approach, a heated nozzle system operating at 830 °C was used to introduce the hydrocarbon radicals onto the substrate which was located a few centimetres below it. Both these approaches rely on the thermal dissociation and recombination of C2H2 for the formation of complex high-order radicals, i.e. C6H9, C5H9, C6H13, whose presence was confirmed by in situ mass spectroscopy. The density of SWCNTs deposited could be correlated directly with the concentration of these precursors.

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

    PubMed

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

    2013-09-01

    The purpose of this study was to develop single walled carbon nanotubes (SWCNT) and poly lactic-co-glycolic acid (PLAGA) composites for orthopedic applications and to evaluate the interaction of human stem cells (hBMSCs) and osteoblasts (MC3T3-E1 cells) via cell growth, proliferation, gene expression, extracellular matrix production and mineralization. PLAGA and SWCNT/PLAGA composites were fabricated with various amounts of SWCNT (5, 10, 20, 40, and 100 mg), characterized and degradation studies were performed. Cells were seeded and cell adhesion/morphology, growth/survival, proliferation and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated uniform incorporation of SWCNT into the PLAGA matrix and addition of SWCNT did not affect the degradation rate. Imaging studies revealed that MC3T3-E1 and hBMSCs cells exhibited normal, non-stressed morphology on the composites and all were biocompatible. Composites with 10 mg SWCNT resulted in highest rate of cell proliferation (p < 0.05) among all composites. Gene expression of alkaline phosphatase, collagen I, osteocalcin, osteopontin, Runx-2, and Bone Sialoprotein was observed on all composites. In conclusion, SWCNT/PLAGA composites imparted beneficial cellular growth capabilities and gene expression, and mineralization abilities were well established. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration and bone tissue engineering (BTE) and are promising for orthopedic applications. PMID:23629922

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

    SciTech Connect

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

    2010-06-15

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

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

    NASA Astrophysics Data System (ADS)

    Campo, Jochen; Fagan, Jeffrey

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

  18. Biodegradation of Single-Walled Carbon Nanotubes by Eosinophil Peroxidase

    PubMed Central

    Andón, Fernando T.; Kapralov, Alexandr A.; Yanamala, Naveena; Feng, Weihong; Baygan, Arjang; Chambers, Benedict J.; Hultenby, Kjell; Ye, Fei; Toprak, Muhammet S.; Brandner, Birgit D.; Fornara, Andrea; Klein-Seetharaman, Judith; Kotchey, Gregg P.; Star, Alexander; Shvedova, Anna A.

    2014-01-01

    Eosinophil peroxidase (EPO) is one of the major oxidant-producing enzymes during inflammatory states in the human lung. The degradation of single-walled carbon nanotubes (SWCNTs) upon incubation with human EPO and H2O2 is reported. Biodegradation of SWCNTs is higher in the presence of NaBr, but neither EPO alone nor H2O2 alone caused the degradation of nanotubes. Molecular modeling reveals two binding sites for SWCNTs on EPO, one located at the proximal side (same side as the catalytic site) and the other on the distal side of EPO. The oxidized groups on SWCNTs in both cases are stabilized by electrostatic interactions with positively charged residues. Biodegradation of SWCNTs can also be executed in an ex vivo culture system using primary murine eosinophils stimulated to undergo degranulation. Biodegradation is proven by a range of methods including transmission electron microscopy, UV-visible-NIR spectroscopy, Raman spectroscopy, and confocal Raman imaging. Thus, human EPO (in vitro) and ex vivo activated eosinophils mediate biodegradation of SWCNTs: an observation that is relevant to pulmonary responses to these materials. PMID:23447468

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  20. Bulk Mechanical Properties of Single Walled Carbon Nanotube Electrodes

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  4. Observation and Modeling of Single Wall Carbon Nanotube Bend Junctions

    NASA Technical Reports Server (NTRS)

    Han, Jie; Anantram, M. P.; Jaffe, R. L.; Kong, J.; Dai, H.; Saini, Subhash (Technical Monitor)

    1998-01-01

    Single wall carbon nanotube (SWNT) bends, with diameters from approx. 1.0 to 2.5 nm and bend angles from 18 deg. to 34 deg., are observed in catalytic decomposition of hydrocarbons at 600 - 1200 C. An algorithm using molecular dynamics simulation (MD) techniques is developed to model these structures that are considered to be SWNT junctions formed by topological defects (i.e. pentagon-heptagon pairs). The algorithm is used to predict the tube helicities and defect configurations for bend junctions using the observed tube diameters and bend angles. The number and arrangement of the defects at the junction interfaces are found to depend on the tube helicities and bend angle. The structural and energetic calculations using the Brenner potential show a number of stable junction configurations for each bend angle with the 34 deg. bends being more stable than the others. Tight binding calculations for local density of state (LDOS) and transmission coefficients are carried out to investigate electrical properties of the bend junctions.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

  8. Ultrathin single-walled carbon nanotube network framed graphene hybrids.

    PubMed

    Wang, Rui; Hong, Tu; Xu, Ya-Qiong

    2015-03-11

    Graphene and single-walled carbon nanotubes (SWNTs) have shown superior potential in electronics and optoelectronics because of their excellent thermal, mechanical, electronic, and optical properties. Here, a simple method is developed to synthesize ultrathin SWNT-graphene films through chemical vapor deposition. These novel two-dimensional hybrids show enhanced mechanical strength that allows them to float on water without polymer supporting layers. Characterizations by Raman spectroscopy and transmission electron microscopy indicate that SWNTs can interlace as a concrete backbone for the subsequent growth of monolayer graphene. Optical and electrical transport measurements further show that SWNT-graphene hybrids inherit high optical transparency and superior electrical conductivity from monolayer graphene. We also explore the local optoelectronic properties of SWNT-graphene hybrids through spatially resolved photocurrent microscopy and find that the interactions between SWNTs and graphene can induce a strong photocurrent response in the areas where SWNTs link different graphene domains together. These fundamental studies may open a door for engineering optoelectronic properties of SWNT-graphene hybrids by controlling the morphologies of the SWNT frames. PMID:25686199

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  11. Single-walled carbon nanotube-induced mitotic disruption⋆

    PubMed Central

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

    2015-01-01

    Carbon nanotubes were among the earliest products of nanotechnology and have many potential applications in medicine, electronics, and manufacturing. The low density, small size, and biological persistence of carbon nanotubes create challenges for exposure control and monitoring and make respiratory exposures to workers likely. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to 24, 48 and 96 μg/cm2 single-walled carbon nanotubes (SWCNT). To investigate mitotic spindle aberrations at concentrations anticipated in exposed workers, primary and immortalized human airway epithelial cells were exposed to SWCNT for 24–72 h at doses equivalent to 20 weeks of exposure at the Permissible Exposure Limit for particulates not otherwise regulated. We have now demonstrated fragmented centrosomes, disrupted mitotic spindles and aneuploid chromosome number at those doses. The data further demonstrated multipolar mitotic spindles comprised 95% of the disrupted mitoses. The increased multipolar mitotic spindles were associated with an increased number of cells in the G2 phase of mitosis, indicating a mitotic checkpoint response. Nanotubes were observed in association with mitotic spindle microtubules, the centrosomes and condensed chromatin in cells exposed to 0.024, 0.24, 2.4 and 24 μg/cm2 SWCNT. Three-dimensional reconstructions showed carbon nanotubes within the centrosome structure. The lower doses did not cause cytotoxicity or reduction in colony formation after 24 h; however, after three days, significant cytotoxicity was observed in the SWCNT-exposed cells. Colony formation assays showed an increased proliferation seven days after exposure. Our results show significant disruption of the mitotic spindle by SWCNT at occupationally relevant doses. The increased proliferation that was observed in carbon nanotube-exposed cells indicates a greater potential to pass the genetic damage to daughter

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

    NASA Astrophysics Data System (ADS)

    Fujimori, Toshihiko; Urita, Koki

    2016-04-01

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

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

    SciTech Connect

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

    2011-12-11

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

  14. Electronic durability of flexible transparent films from type-specific single-wall carbon nanotubes.

    PubMed

    Harris, John M; Iyer, Ganjigunte R Swathi; Bernhardt, Anna K; Huh, Ji Yeon; Hudson, Steven D; Fagan, Jeffrey A; Hobbie, Erik K

    2012-01-24

    The coupling between mechanical flexibility and electronic performance is evaluated for thin films of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) deposited on compliant supports. Percolated networks of type-purified SWCNTs are assembled as thin conducting coatings on elastic polymer substrates, and the sheet resistance is measured as a function of compression and cyclic strain through impedance spectroscopy. The wrinkling topography, microstructure and transparency of the films are independently characterized using optical microscopy, electron microscopy, and optical absorption spectroscopy. Thin films made from metallic SWCNTs show better durability as flexible transparent conductive coatings, which we attribute to a combination of superior mechanical performance and higher interfacial conductivity. PMID:22148890

  15. Donor doping of single-walled carbon nanotubes by filling of channels with silver

    SciTech Connect

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

    2012-09-15

    The channels of single-walled carbon nanotubes (SWNTs) are filled with metallic silver. The synthesized nanocomposites are studied by Raman spectroscopy and optical absorption spectroscopy, and these data indicate a substantial modification of the electronic structure of the nanotubes upon their filling. Moreover, X-ray photoelectron spectroscopy shows that the incorporation of the metal leads to a change in the work function of SWNTs due to the Fermi level upshift and to the transfer of an electron density from inserted nanoparticles to the nanotube walls. Thus, the filling of the channels with silver results in donor doping of the nanotubes.

  16. Elastomer Filled With Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Files, Bradley S.; Forest, Craig R.

    2004-01-01

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

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

    DOEpatents

    Biris, Alexandru S.; Li, Zhongrui

    2012-11-06

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

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

    ERIC Educational Resources Information Center

    Liu, Xiaolai; Zhao, Donglin

    2009-01-01

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

  19. Toroidal Single Wall Carbon Nanotubes in Fullerene Crop Circles

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  20. Single-walled carbon nanotube networks in conductive composite materials.

    PubMed

    Bârsan, Oana A; Hoffmann, Günter G; van der Ven, Leo G J; de With, G Bert

    2014-01-01

    Electrically conductive composite materials can be used for a wide range of applications because they combine the advantages of a specific polymeric material (e.g., thermal and mechanical properties) with the electrical properties of conductive filler particles. However, the overall electrical behaviour of these composite materials is usually much below the potential of the conductive fillers, mainly because by mixing two different components, new interfaces and interphases are created, changing the properties and behaviours of both. Our goal is to characterize and understand the nature and influence of these interfaces on the electrical properties of composite materials. We have improved a technique based on the use of sodium carboxymethyl cellulose (CMC) to disperse single-walled carbon nanotubes (SWCNTs) in water, followed by coating glass substrates, and drying and removing the CMC with a nitric acid treatment. We used electron microscopy and atomic force microscopy techniques to characterize the SWCNT films, and developed an in situ resistance measurement technique to analyse the influence of both the individual components and the mixture of an epoxy/amine system on the electrical behaviour of the SWCNTs. The results showed that impregnating a SWCNT network with a polymer is not the only factor that affects the film resistance; air exposure, temperature, physical and chemical properties of the individual polymer components, and also the formation of a polymeric network, can all have an influence on the macroscopic electrical properties of the initial SWCNT network. These results emphasize the importance of understanding the effects that each of the components can have on each other before trying to prepare an efficient polymer composite material. PMID:25430670

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

    NASA Astrophysics Data System (ADS)

    Khmelinskii, Igor; Makarov, Vladimir

    2016-09-01

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

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

    NASA Technical Reports Server (NTRS)

    Bley, Richard A.

    2007-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Lebron, Marisabel; Meador, Michael A.

    2003-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  5. Terahertz Spectroscopy of Individual Single-Walled Carbon Nanotubes as a Probe of Luttinger Liquid Physics.

    PubMed

    Chudow, Joel D; Santavicca, Daniel F; Prober, Daniel E

    2016-08-10

    Luttinger liquid theory predicts that collective electron excitations due to strong electron-electron interactions in a one-dimensional (1D) system will result in a modification of the collective charge-propagation velocity. By utilizing a circuit model for an individual metallic single-walled carbon nanotube as a nanotransmission line, it has been shown that the frequency-dependent terahertz impedance of a carbon nanotube can probe this expected 1D Luttinger liquid behavior. We excite terahertz standing-wave resonances on individual antenna-coupled metallic single-walled carbon nanotubes. The terahertz signal is rectified using the nanotube contact nonlinearity, allowing for a low-frequency readout of the coupled terahertz current. The charge velocity on the nanotube is determined from the terahertz spectral response. Our measurements show that a carbon nanotube can behave as a Luttinger liquid system with charge-propagation velocities that are faster than the Fermi velocity. Understanding what determines the charge velocity in low-dimensional conductors is important for the development of next generation nanodevices. PMID:27439013

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

    SciTech Connect

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

    2008-09-07

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

  7. Stabilities and mechanical and electronic properties on BN doped zigzag single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Vongachariya, Arthit; Parasuk, Vudhichai

    2015-12-01

    Electronic structures of undoped and BN doped zigzag (8,0) single-walled carbon nanotube (SWCNT) were investigated using density functional theoretical calculations. Their stabilities due to BN doping and spin states were considered and those with the shortest B-N distance and singlet spin is the most stable. The BN substitution also causes the reduction of the band gap energy. While the BN doping reduces the band gap energy from 0.606 to 0.183 eV, it has no effect on the Young's modulus value. The band gap energy of SWCNTs can be varied upon applying stress. At high stress ratio, SWCNT could become metallic.

  8. Growth of semiconducting single-walled carbon nanotubes by using ceria as catalyst supports.

    PubMed

    Qin, Xiaojun; Peng, Fei; Yang, Feng; He, Xiaohui; Huang, Huixin; Luo, Da; Yang, Juan; Wang, Sheng; Liu, Haichao; Peng, Lianmao; Li, Yan

    2014-02-12

    The growth of semiconducting single-walled carbon nanotubes (s-SWNTs) on flat substrates is essential for the application of SWNTs in electronic and optoelectronic devices. We developed a flexible strategy to selectively grow s-SWNTs on silicon substrates using a ceria-supported iron or cobalt catalysts. Ceria, which stores active oxygen, plays a crucial role in the selective growth process by inhibiting the formation of metallic SWNTs via oxidation. The so-produced ultralong s-SWNT arrays are immediately ready for building field effect transistors. PMID:24392872

  9. Temperature dependence of plasmon resonance in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Morimoto, Takahiro; Ichida, Masao; Ikemoto, Yuka; Okazaki, Toshiya

    2016-05-01

    The temperature dependence of the optical response in the far-infrared (FIR) region of metallic and semiconducting rich single-walled carbon nanotubes (SWCNTs) was investigated by micro-Fourier transform infrared spectrometry with a focused beam of synchrotron radiation. The temperature dependence of the FIR spectra of both types of SWCNT showed negligibly small variations within a wide temperature range from 4 to 300 K. Upon comparison with a theoretical model for the diffusive region, it is speculated that these results might have been caused by a strong suppression of phonon scattering in relatively short CNTs with lengths of less than 1 μm.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  11. Electronic properties of mechanically induced kinks in single-walled carbon nanotubes

    SciTech Connect

    Bozovic, Dolores; Bockrath, M.; Hafner, Jason H.; Lieber, Charles M.; Park, Hongkun; Tinkham, M.

    2001-06-04

    We have used an atomic-force microscope tip to mechanically buckle single-walled carbon nanotubes. The resistance of the induced defects ranged from 10 to 100 k{Omega} and varied with the local Fermi level, as determined by scanned-gate microscopy. By forming two closely spaced defects on metallic nanotubes, we defined quantum dots less than 100 nm in length. These devices exhibited single-electron charging behavior at temperatures up to {similar_to}165 K. {copyright} 2001 American Institute of Physics.

  12. Single Walled Carbon Nanohorns as Photothermal Cancer Agents

    SciTech Connect

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

    2011-01-01

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

  13. Structural characterization of macroscopic single-walled carbon nanotube materials

    NASA Astrophysics Data System (ADS)

    Zhou, Wei

    In this thesis, we studied the structural properties of macroscopic materials of single-walled carbon nanotubes (SWNTs) in the form of fibers, films and suspensions. We characterized the preferred orientations in partially aligned SWNT fibers and films, combining x-ray fiber diagram and polarized Raman scattering. Our texture model consists of an aligned fraction, characterized by the angular distribution width of tube axes, plus a completely unaligned fraction. For neat fibers extruded from SWNT/superacid suspensions through a small orifice, the distribution width and the aligned fraction both improve with decreasing orifice diameter. For magnetic field-aligned SWNT films deposited from surfactant suspensions, the aligning effects of deposition and external magnetic field force in the film plane are additive, the out-of-plane mosaic being narrower than the in-plane one. SWNTs dispersed in superacid or aqueous surfactant solutions are precursors for many applications. In oleum, SWNTs can be charged and protonated by H 2SO4 molecules. X-ray scattering indicates that H2SO 4 molecules align along nanotube axes to form cylindrical shells wrapped around nanotubes. This finding establishes the validity of a long-standing important but still debated physical chemistry concept, "structured solvent shells surrounding dissolved ions". Differential scanning calorimetry confirms that the partly ordered H2SO4 molecules are a new phase, with distinct freezing/melting behavior. X-ray scattering at low temperature further shows that crystallization of the bulk-like acid surrounding the structured shells is templated by the SWNTs. The specific orientation of the acid crystallites provides solid evidence for direct protonation of SWNT. We studied the morphologies of SWNT suspensions using small-angle neutron scattering. We observed rigid rod behavior from SWNTs dispersed in water using sodium dodecylbenzene sulfonate surfactant, suggesting that SWNTs exist mainly as individual tube

  14. Antimicrobial Biomaterials based on Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Aslan, Seyma

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

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

    PubMed

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

    2015-03-18

    The real-time temperature measurement of nanostructured materials is particularly attractive in view of increasing needs of local temperature probing with high sensitivity and resolution in nanoelectronics, integrated photonics, and biomedicine. Light-induced heating and Raman scattering of single-walled carbon nanotubes with adsorbed gold nanoparticles decorating silica microparticles are reported, by both green and near IR lasers. The plasmonic shell is used as nanoheater, while the single-walled carbon nanotubes are Raman active and serve as a thermometer. Stokes and Anti-Stokes Raman spectra of single-walled carbon nanotubes serve to estimate the effective light-induced temperature rise on the metal nanoparticles. The temperature rise is constant with time, indicating stability of the adsorption density. The effective temperatures derived from Stokes and Anti-Stokes intensities are correlated with those measured in a heating stage. The resolution of the thermal experiments in our study was found to be 5-40 K. PMID:25367373

  16. Single-walled carbon nanotube networks for flexible and printed electronics

    NASA Astrophysics Data System (ADS)

    Zaumseil, Jana

    2015-07-01

    Networks of single-walled carbon nanotubes (SWNTs) can be processed from solution and have excellent mechanical properties. They are highly flexible and stretchable. Depending on the type of nanotubes (semiconducting or metallic) they can be used as replacements for metal or transparent conductive oxide electrodes or as semiconducting layers for field-effect transistors (FETs) with high carrier mobilities. They are thus competitive alternatives to other solution-processable materials for flexible and printed electronics. This review introduces the basic properties of SWNTs, current methods for dispersion and separation of metallic and semiconducting SWNTs and techniques to deposit and pattern dense networks from dispersion. Recent examples of applications of carbon nanotubes as conductors and semiconductors in (opto-)electronic devices and integrated circuits will be discussed.

  17. Selective Oxidation of Amorphous Carbon Layers without Damaging Embedded Single Wall Carbon Nanotube Bundles

    NASA Astrophysics Data System (ADS)

    Choi, Young Chul; Lim, Seong Chu

    2013-11-01

    Single wall carbon nanotubes (SWCNTs) were synthesized by arc discharge, and then purified by selective oxidation of amorphous carbon layers that were found to encase SWCNT bundles and catalyst metal particles. In order to remove selectively the amorphous carbon layers with SWCNTs being intact, we have systematically investigated the thermal treatment conditions; firstly, setting the temperature by measuring the activation energies of SWCNTs and amorphous carbon layers, and then, secondly, finding the optimal process time. As a consequence, the optimal temperature and time for the thermal treatment was found to be 460 °C and 20 min, respectively. The complete elimination of surrounding amorphous carbon layers makes it possible to efficiently disperse the SWCNT bundles, resulting in high absorbance of SWCNT-ink. The SWCNTs which were thermal-treated at optimized temperature (460 °C) and duration (20 min) showed much better crystallinity, dispersibility, and transparent conducting properties, compared with as-synthesized and the nanotubes thermal-treated at different experimental conditions.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    PubMed Central

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

    2009-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  1. Cu/single-walled carbon nanotube laminate composites fabricated by cold rolling and annealing

    NASA Astrophysics Data System (ADS)

    Li, Yan-Hui; Housten, William; Zhao, Yimin; Qiu Zhu, Yan

    2007-05-01

    The remarkable mechanical, electrical and thermal properties of single-walled carbon nanotubes (SWCNTs) have attracted extensive research interest as structural and functional materials. In particular, SWCNTs have been used to reinforce polymers and ceramic composites and great progress has been made. For metal matrix composites, the limitation of the conventional manufacturing process and the difficulty in dispersing nanotubes within metal matrices hinder the development of metal matrix composites. In this paper, we demonstrate a successful fabrication of Cu/SWCNT laminate composites by combined techniques of cold rolling and annealing, using 19 layers of large-area SWCNT films sandwiched between 20 layers of Cu thin foils. The tensile strength and Young's modulus of the resultant laminate composites are 361 MPa and 132 GPa, respectively, exhibiting an improvement over the comparative pure Cu foils processed under identical conditions. These results suggest that good interfacial adhesions between nanotubes and the Cu matrix have been achieved after the rolling-annealing-rolling processes.

  2. Nickel-cobalt nanoparticles supported on single-walled carbon nanotubes and their catalytic hydrogenation activity.

    PubMed

    Lekgoathi, Mpho D S; Augustyn, Willem G; Heveling, Josef

    2011-08-01

    Single-walled carbon nanotubes were synthesized from graphite using the arc discharge technique. A nickel/yttrium/graphite mixture was used as the catalyst. After purification by sonication in a Triton X-100 solution, nickel-cobalt metal nanoparticles were deposited on the surface of the single-walled carbon nanotubes. The resulting material and/or the nanotubes themselves were characterized by physisorption, Raman spectroscopy, high-resolution transition electron microscopy and X-ray diffraction. Raman spectroscopy indicates that the nanotubes, prepared by the arc discharge technique, are semi-conducting with a diameter centering at 1.4 nm. The average nickel-cobalt particle size is estimated to be in the region of 8 nm. The catalytic activity of the material was examined for the hydrogenation of unsaturated fatty acid methyl esters obtained from avocado oil. The carbon nanotube supported nickel-cobalt particles effectively hydrogenate polyunsaturated methyl linoleate to monounsaturated methyl oleate. In contrast to a conventional nickel on kieselghur catalyst, further hydrogenation of methyl oleate to undesired methyl stearate was not observed. PMID:22103112

  3. Interaction between fullerene halves Cn (n ≤ 40) and single wall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Sharma, Amrish; Kaur, Sandeep; Mudahar, Isha

    2016-05-01

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

  4. Evidence for substitutional boron in doped single-walled carbon nanotubes

    SciTech Connect

    Ayala, P.; Pichler, T.; Reppert, J.; Rao, A. M.; Grobosch, M.; Knupfer, M.

    2010-05-03

    Precise determination of acceptors in the laser ablation grown B doped single-walled carbon nanotubes (SWCNTs) has been elusive. Photoemission spectroscopy finds evidence for subpercent substitutional B in this material, which leads to superconductivity in thin film SWNT samples.

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

    PubMed Central

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

    2016-01-01

    The dynamic evolution of nanocatalyst particle shape and carbon composition during the initial stages of single-walled carbon nanotube growth by chemical vapor deposition synthesis is investigated. Classical reactive and ab initio molecular dynamics simulations are used, along with environmental transmission electron microscope video imaging analyses. A clear migration of carbon is detected from the nanocatalyst/substrate interface, leading to a carbon gradient showing enrichment of the nanocatalyst layers in the immediate vicinity of the contact layer. However, as the metal nanocatalyst particle becomes saturated with carbon, a dynamic equilibrium is established, with carbon precipitating on the surface and nucleating a carbon cap that is the precursor of nanotube growth. A carbon composition profile decreasing towards the nanoparticle top is clearly revealed by the computational and experimental results that show a negligible amount of carbon in the nanoparticle region in contact with the nucleating cap. The carbon composition profile inside the nanoparticle is accompanied by a well-defined shape evolution of the nanocatalyst driven by the various opposing forces acting upon it both from the substrate and from the nascent carbon nanostructure. This new understanding suggests that tuning the nanoparticle/substrate interaction would provide unique ways of controlling the nanotube synthesis. PMID:26900454

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

    NASA Astrophysics Data System (ADS)

    Caldwell, Robert Victor

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

  7. Properties of single wall carbon nanotubes array antennas in the optical regime

    NASA Astrophysics Data System (ADS)

    Wu, Xiaofang; Jiang, Yuesong; Hua, Houqiang

    2014-11-01

    Single wall carbon nanotubes (SWCNTs) can be metallic, depending on their chirality. For their nanoscale geometric dimension, SWCNTs can be used as antennas to convert high-frequency electromagnetic radiation such as optical radiation into localized energy and vice versa. However, at optical frequencies, traditional antenna design theory fails for metals behave as strongly coupled plasmas. As a matter of fact, an optical antenna responds to a shorter effective wavelength which depends on the material properties and geometric parameters. In this letter, we derived the relationship of effective wavelength with the wavelength of incident radiation for SWCNTs optical antenna, assuming that the SWCNTs can be described by a free electron gas according to the Drude model. SWCNTs optical antenna holds great promise for increasing solar energy conversion efficiency.

  8. Ultrafast nonlinear photoresponse of single-wall carbon nanotubes: a broadband degenerate investigation.

    PubMed

    Xu, Shuo; Wang, Fengqiu; Zhu, Chunhui; Meng, Yafei; Liu, Yujie; Liu, Wenqing; Tang, Jingyi; Liu, Kaihui; Hu, Guohua; Howe, Richard C T; Hasan, Tawfique; Zhang, Rong; Shi, Yi; Xu, Yongbing

    2016-04-28

    Understanding of the fundamental photoresponse of carbon nanotubes has broad implications for various photonic and optoelectronic devices. Here, Z-scan and pump-probe spectroscopy performed across 600-2400 nm were combined to give a broadband 'degenerate' mapping of the nonlinear absorption properties of single-wall carbon nanotubes (SWNTs). In contrast to the views obtained from non-degenerate techniques, sizable saturable absorption is observed from the visible to the near-infrared range, including the spectral regions between semiconducting excitonic peaks and metallic tube transitions. In addition, the broadband mapping unambiguously reveals a photobleaching to photoinduced absorption transition feature within the first semiconducting excitonic band ∼2100 nm, quantitatively marking the long-wavelength cut-off for saturable absorption of the SWNTs investigated. Our findings present a much clearer physical picture of SWNTs' nonlinear absorption characteristics, and help provide updated design guidelines for SWNT based nonlinear optical devices. PMID:27088630

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2000-11-01

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

  11. The separation and substrate independent organization of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Debjit D.

    Learning how to separate, purify and manipulate single wall carbon nanotubes (SWNTs) presents a unique challenge in material science. The processing-related difficulties of these long nano-fibers stem from their high aspect ratio, rigidity and the profound hydrophobic attractions along their tubular walls. Shortening them into discrete segments, with lengths from tens to hundreds of nanometers, presents a viable methodology to alleviate the shape-induced intractability. The thesis presents a route for the length fractionation of shortened-S WNTs, and most importantly provides a venue by which substantial separation of single wall carbon nanotubes (SWNTs) according to type (metallic versus semiconducting) has been achieved for HiPco and laser-ablated SWNTs. Herein I argue that stable dispersions of SWNTs with octadecylamine (ODA) in tetrahydrofuran (THF) originate from the physisorption and organization of ODA along the SWNT sidewalls in addition to the originally proposed zwitterion model. Furthermore, the reported affinity of amine groups for semiconducting SWNTs, as opposed to their metallic counterparts contributes additional stability to the physisorbed ODA. This provides a venue for the selective precipitation of metallic SWNTs upon increasing dispersion concentration, as indicated by Raman investigations. In addition, the thesis provides a novel metal-assisted self-organization of these nanosized objects into nano-forest geometries with dense perpendicular surface grafting, and demonstrates that such nanosized objects hold significant promise for the development of nanoscale sensors. Additionally, this dissertation provides a method for the complete elimination of catalytic impurities from SWNTs. Electrochemical actuators using such purified SWNTs have been characterized.

  12. Ultrafast nonlinear photoresponse of single-wall carbon nanotubes: a broadband degenerate investigation

    NASA Astrophysics Data System (ADS)

    Xu, Shuo; Wang, Fengqiu; Zhu, Chunhui; Meng, Yafei; Liu, Yujie; Liu, Wenqing; Tang, Jingyi; Liu, Kaihui; Hu, Guohua; Howe, Richard C. T.; Hasan, Tawfique; Zhang, Rong; Shi, Yi; Xu, Yongbing

    2016-04-01

    Understanding of the fundamental photoresponse of carbon nanotubes has broad implications for various photonic and optoelectronic devices. Here, Z-scan and pump-probe spectroscopy performed across 600-2400 nm were combined to give a broadband `degenerate' mapping of the nonlinear absorption properties of single-wall carbon nanotubes (SWNTs). In contrast to the views obtained from non-degenerate techniques, sizable saturable absorption is observed from the visible to the near-infrared range, including the spectral regions between semiconducting excitonic peaks and metallic tube transitions. In addition, the broadband mapping unambiguously reveals a photobleaching to photoinduced absorption transition feature within the first semiconducting excitonic band ~2100 nm, quantitatively marking the long-wavelength cut-off for saturable absorption of the SWNTs investigated. Our findings present a much clearer physical picture of SWNTs' nonlinear absorption characteristics, and help provide updated design guidelines for SWNT based nonlinear optical devices.Understanding of the fundamental photoresponse of carbon nanotubes has broad implications for various photonic and optoelectronic devices. Here, Z-scan and pump-probe spectroscopy performed across 600-2400 nm were combined to give a broadband `degenerate' mapping of the nonlinear absorption properties of single-wall carbon nanotubes (SWNTs). In contrast to the views obtained from non-degenerate techniques, sizable saturable absorption is observed from the visible to the near-infrared range, including the spectral regions between semiconducting excitonic peaks and metallic tube transitions. In addition, the broadband mapping unambiguously reveals a photobleaching to photoinduced absorption transition feature within the first semiconducting excitonic band ~2100 nm, quantitatively marking the long-wavelength cut-off for saturable absorption of the SWNTs investigated. Our findings present a much clearer physical picture of

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Single walled carbon nanotube network (SWCNTN) was coated by tetrahedral amorphous carbon (ta-C) using a pulsed Filtered Cathodic Vacuum Arc system to form a SWCNTN—ta-C composite film. The effects of SWCNTN areal coverage density and ta-C coating thickness on the composite film properties were investigated. X-Ray photoelectron spectroscopy measurements prove the presence of high quality sp3 bonded ta-C coating on the SWCNTN. Raman spectroscopy suggests that the single wall carbon nanotubes (SWCNTs) forming the network survived encapsulation in the ta-C coating. Nano-mechanical testing suggests that the ta-C coated SWCNTN has superior wear performance compared to uncoated SWCNTN.

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

    SciTech Connect

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

    2015-06-14

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    DOEpatents

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

    2014-09-23

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

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

    DOEpatents

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

    2008-10-07

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

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

    PubMed

    Rana, Sohel; Alagirusamy, Ramasamy; Joshi, Mangala

    2011-08-01

    In the present work, single-walled carbon nanotubes were dispersed within the matrix of carbon fabric reinforced epoxy composites in order to develop novel three phase carbon/epoxy/single-walled carbon nanotube composites. A combination of ultrasonication and high speed mechanical stirring at 2000 rpm was used to uniformly disperse carbon nanotubes in the epoxy resin. The state of carbon nanotube dispersion in the epoxy resin and within the nanocomposites was characterized with the help of optical microscopy and atomic force microscopy. Pure carbon/epoxy and three phase composites were characterized for mechanical properties (tensile and compressive) as well as for thermal and electrical conductivity. Fracture surfaces of composites after tensile test were also studied in order to investigate the effect of dispersed carbon nanotubes on the failure behavior of composites. Dispersion of only 0.1 wt% nanotubes in the matrix led to improvements of 95% in Young's modulus, 31% in tensile strength, 76% in compressive modulus and 41% in compressive strength of carbon/epoxy composites. In addition to that, electrical and thermal conductivity also improved significantly with addition of carbon nanotubes. PMID:22103118

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

    PubMed Central

    2010-01-01

    In this letter, we report that dysprosium is an effective catalyst for single-walled carbon nanotubes (SWNTs) growth via a chemical vapor deposition (CVD) process for the first time. Horizontally superlong well-oriented SWNT arrays on SiO2/Si wafer can be fabricated by EtOH-CVD under suitable conditions. The structure and properties are characterized by scanning electron microscopy, transition electron microscopy, Raman spectroscopy and atomic force microscopy. The results show that the SWNTs from dysprosium have better structural uniformity and better conductivity with fewer defects. This rare earth metal provides not only an alternative catalyst for SWNTs growth, but also a possible method to generate high percentage of superlong semiconducting SWNT arrays for various applications of nanoelectronic device. PMID:20672139

  20. Temperature induced modification of the mid-infrared response of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shuba, Mikhail V.; Paddubskaya, Alesia G.; Kuzhir, Polina P.; Maksimenko, Sergey A.; Valusis, Gintaras; Poklonski, Nikolai A.; Bellucci, Stefano; Kenanakis, George; Kafesaki, Maria

    2016-03-01

    The temperature dependences of the absorbance spectra of thin free-standing single-walled carbon nanotube (SWCNT) films were studied in the infrared range (700-6200 cm-1) while heating the air from 300 to 575 K. The observed temperature variation in the infrared absorbance spectra has been explained by two different physical factors. The first one is the strong temperature dependence of the conductivity of p-type doped semiconducting SWCNTs. The second one is the temperature dependence of electron relaxation time of intraband electron transitions in metallic SWCNTs. The possibility of the separation of contributions from the interband and intraband transitions to the infrared spectra of SWCNT films has been demonstrated.

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

    SciTech Connect

    Diniz, Ginetom S. Ulloa, Sergio E.

    2014-07-14

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  3. All-printed and transparent single walled carbon nanotube thin film transistor devices

    NASA Astrophysics Data System (ADS)

    Sajed, Farzam; Rutherglen, Christopher

    2013-09-01

    We present fully transparent single-walled all-carbon nanotube thin film transistors (SWCNT TFT) fabricated using low-cost inkjet printing methods. Such a demonstration provides a platform towards low cost fully printed transparent electronics. The SWCNT TFTs were printed with metallic and semiconducting SWCNT using a room temperature printing process, without the requirement of expensive cleanroom facilities. The unoptimized SWCNT TFTs fabricated exhibited an Ion/off ratio of 92 and mobility of 2.27 cm2V-1s-1 and transmissivity of 82%. The combination of both high electrical performance and high transparency make all-SWCNT TFTs desirable for next generation transparent display backplanes and products such as Google Glass.

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

    PubMed

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

    2015-12-22

    High purity semiconducting single-walled carbon nanotubes (s-SWCNTs) with a narrow diameter distribution are required for high-performance transistors. Achieving this goal is extremely challenging because the as-grown material contains mixtures of s-SWCNTs and metallic- (m-) SWCNTs with wide diameter distributions, typically inadequate for integrated circuits. Since 2000, numerous ex situ methods have been proposed to improve the purity of the s-SWCNTs. The majority of these techniques fail to maintain the quality and integrity of the s-SWCNTs with a few notable exceptions. Here, the progress in realizing high purity s-SWCNTs in as-grown and post-processed materials is highlighted. A comparison of transistor parameters (such as on/off ratio and field-effect mobility) obtained from test structures establishes the effectiveness of various methods and suggests opportunities for future improvements. PMID:26540144

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

    Lian, Chao-Sheng; Wang, Jian-Tao

    2014-05-28

    We explore by ab initio calculations the possible crystalline phases of polymerized single-wall carbon nanotubes (P-SWNTs) and determine their structural, elastic, and electronic properties. Based on direct cross-linking and intertube sliding-assisted cross-linking mechanisms, we have identified a series of stable three-dimensional polymeric structures for the zigzag nanotubes up to (10,0). Among proposed P-SWNT phases, the structures with favorable diamond-like sp(3) intertube bonding configuration and small tube cross-section distortion are found to be the most energetically stable ones. These polymeric crystalline phases exhibit high bulk and shear moduli superior to SWNT bundles, and show metallic or semiconducting properties depending on the diameter of constituent tubes. We also propose by hydrostatic pressure simulations that the intertube sliding between van der Waals bonded nanotubes may be an effective route to promote the polymerization of SWNTs under pressure. PMID:24880313

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

    SciTech Connect

    Lian, Chao-Sheng; Wang, Jian-Tao

    2014-05-28

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

  8. Analysis of Stress Responsive Genes Induced by Single-Walled Carbon Nanotubes in BJ Foreskin Cells

    PubMed Central

    Sarkar, Shubhashish; Sharma, Chidananda; Yog, Rajeshwari; Periakaruppan, Adaikkappan; Jejelowo, Olufisayo; Thomas, Renard; Barrera, Enrique V.; Rice-Ficht, Allison C.; Wilson, Bobby L.; Ramesh, Govindarajan T.

    2009-01-01

    Nanotechnology is finding its use as a potential technology in consumer products, defense, electronics, and medical applications by exploiting the properties of nanomaterials. Single-walled carbon nanotubes are novel forms of these nanomaterials with potential for large applications. However, the toxicity studies on this material are not explored in detail and therefore limiting its use. It has been earlier reported that single-walled carbon nanotubes induces oxidative stress and also dictates activation of specific signaling pathway in keratinocytes. The present study explores the effect of single-walled carbon nanotubes on stress genes in human BJ Foreskin cells. The results show induction of oxidative stress in BJ Foreskin cells by single-walled carbon nanotubes and increase in stress responsive genes. The genes included inducible genes like HMOX1, HMOX2, and Cyp1B1. In addition we validated increase for four genes by SWCNT, namely ATM, CCNC, DNAJB4, and GADD45A by RT-PCR. Moreover results of the altered stress related genes have been discussed and that partially explains some of the toxic responses induced by single-walled carbon nanotubes. PMID:17450800

  9. Systematic conversion of single walled carbon nanotubes into n-type thermoelectric materials by molecular dopants.

    PubMed

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

    2013-01-01

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

  10. Molecular dynamics study of electron-irradiation effects in single-walled carbon nanotubes

    SciTech Connect

    Yasuda, Masaaki; Kimoto, Yoshihisa; Tada, Kazuhiro; Mori, Hideki; Akita, Seiji; Hirai, Yoshihiko; Nakayama, Yoshikazu

    2007-05-15

    Molecular dynamics studies are carried out to investigate electron-irradiation effects in single-walled carbon nanotubes. We have proposed a simulation model which includes the interaction between a high-energy incident electron and a carbon atom, based on Monte Carlo method using the elastic-scattering cross section. The atomic level behavior of a single-walled carbon nanotube under electron irradiation is demonstrated in nanosecond time scale. The incident electron energy, tube diameter, and tube temperature dependences of electron-irradiation effects are studied with the simulation.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  12. Temperature threshold and water role in CVD growth of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Geng, Junfeng; Motta, Marcelo; Angels, Volker; Luo, Jikui; Johnson, Brian

    2016-02-01

    An in-depth understanding of the growth process of single walled carbon nanotubes is of vital importance to the control of the yield of the material and its carbon structure. Using a nickel/silica (Ni/SiOx) catalyst we have conducted a series of growth experiments with a chemical vapour deposition (CVD) system. We find that there is a temperature threshold in the CVD process, and if the reaction temperature sets above this threshold there will be no growth of the nanotubes. In association with this temperature effect, water plays an important role in the promotion or termination of the growth of single walled carbon nanotubes.

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

    SciTech Connect

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

    2015-08-15

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

  14. Dissolution of single-walled carbon nanotubes in alkanol-cholic acid mixtures

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    A procedure for dispersing the single-walled carbon nanotubes (SWCNTs) for preparing stable suspensions with high concentrations of individual nanotubes in various alcohols was described. The obtained suspensions were studied by Raman spectroscopy. The solubility of the single-walled carbon nanotubes in alcohols was found to depend on the concentration of cholic acid. The ethanol-surfactant mixture was shown to be the best solvent for all alkanol-cholic acid mixtures (0.018 mol/kg) under study used for preparing time-stable suspensions of single-walled carbon nanotubes. The dissolving ability of aliphatic alcohols was found to decrease in the series: ethanol-isopropanol- tert-butanol-butanol-propanol.

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

    SciTech Connect

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

    2014-01-28

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

  16. Single walled carbon nanotube growth and chirality dependence on catalyst composition

    NASA Astrophysics Data System (ADS)

    Orbaek, Alvin W.; Owens, Andrew C.; Crouse, Christopher C.; Pint, Cary L.; Hauge, Robert H.; Barron, Andrew R.

    2013-09-01

    Vertical arrays of single walled carbon nanotubes (VA-SWNTs) were grown using bi-metallic nanoparticle pro-catalysts. Iron oxide particles were doped with varying quantities of first row transition metals (Mn, Co, Ni, and Cu) for a comparative study of the growth of nanotubes. VA-CNT samples were verified using scanning electron microscopy, and characterized using resonance Raman spectroscopy. The length of the VA-CNTs is used as a measure of catalyst activity: the presence of dopants results in a change in the CNT length and length distribution. Cross correlation of the Raman spectra reveal variations in the distribution of radial breathing mode peaks according to the pro-catalyst composition. The formation of various chirality nanotubes is constant between repetitive runs with a particular catalyst, but may be controlled by the identity and concentration of the metal dopants within the iron catalyst. These results demonstrate that the composition of the catalyst is a major driving force toward type selective growth of nanotubes.Vertical arrays of single walled carbon nanotubes (VA-SWNTs) were grown using bi-metallic nanoparticle pro-catalysts. Iron oxide particles were doped with varying quantities of first row transition metals (Mn, Co, Ni, and Cu) for a comparative study of the growth of nanotubes. VA-CNT samples were verified using scanning electron microscopy, and characterized using resonance Raman spectroscopy. The length of the VA-CNTs is used as a measure of catalyst activity: the presence of dopants results in a change in the CNT length and length distribution. Cross correlation of the Raman spectra reveal variations in the distribution of radial breathing mode peaks according to the pro-catalyst composition. The formation of various chirality nanotubes is constant between repetitive runs with a particular catalyst, but may be controlled by the identity and concentration of the metal dopants within the iron catalyst. These results demonstrate that the

  17. Investigation on vibration of single-walled carbon nanotubes by variational iteration method

    NASA Astrophysics Data System (ADS)

    Ahmadi Asoor, A. A.; Valipour, P.; Ghasemi, S. E.

    2016-02-01

    In this paper, the variational iteration method (VIM) has been used to investigate the non-linear vibration of single-walled carbon nanotubes (SWCNTs) based on the nonlocal Timoshenko beam theory. The accuracy of results is examined by the fourth-order Runge-Kutta numerical method. Comparison between VIM solutions with numerical results leads to highly accurate solutions. Also, the behavior of deflection and frequency in vibrations of SWCNTs are studied. The results show that frequency of single walled carbon nanotube versus amplitude increases by increasing the values of B.

  18. Free vibration analysis of fluid-conveying single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Reddy, C. D.; Lu, C.; Rajendran, S.; Liew, K. M.

    2007-03-01

    The effect of fluid flow on the free vibration and instability of fluid-conveying single-walled carbon nanotubes is studied. The possibility of developing a technique to measure the mass flow rate of fluid is examined. Atomistic simulations and the continuum beam model are used. Simulations are performed to quantify the inertial, stiffness, Coriolis, and centrifugal forces generated by flow during the free vibration. A numerical expression is developed to measure the mass flow rate of the fluid velocities up to 40% of the critical flow velocity. This observation is useful to quantify the mass flow measurement of fluid conveying single-walled carbon nanotubes.

  19. Bolometric detector on the basis of single-wall carbon nanotube/polymer composite

    NASA Astrophysics Data System (ADS)

    Aliev, Ali E.

    2008-10-01

    Infrared imaging sensors that operate without cryogenic cooling have the potential to provide the military or civilian users with infrared vision capabilities packaged in a camera of extremely small size, weight and power consumption. We present here the uncooled bolometric sensor on the basis of single-walled carbon nanotubes (SWNTs) polymer composite with enhanced sensitivity. The voltage responsivity of device working at room temperatures exceeds 150 V/W. The absorption coefficient of single-wall carbon nanotubes was increased by involving Forster type energy transfer from polymer film to dispersed SWNT. The temperature gradient of resistivity was substantially improved by chemical functionalization of SWNT.

  20. Limits of the PECVD process for single wall carbon nanotubes growth

    NASA Astrophysics Data System (ADS)

    Gohier, A.; Minea, T. M.; Djouadi, A. M.; Granier, A.; Dubosc, M.

    2006-04-01

    This Letter explores the capabilities of plasma enhanced chemical vapor deposition to grow vertical oriented single wall, double wall or multi walled carbon nanotubes (CNTs). Our dual process uses high-density low-pressure plasma excited by electron cyclotron resonance using acetylene diluted in ammonia. The early stages of CNTs synthesis have been probed taking advantage of the low growth rate of our process. Two antagonist effects have been shown up: the formation of catalyzed carbon nanotubes against ion assisted bonds breaking. The limits of plasma single wall CNTs growth are discussed and transitory stages have been revealed for the first time.

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

    PubMed

    Suzuki, Tomoko; Inoue, Sakae; Ando, Yoshinori

    2010-06-01

    In the arc plasma jet (APJ) method, a large amount of soot including single wall carbon nanotubes (SWNTs) can be produced in a short time. However, as-grown soot contains a lot of impurities, such as metallic particles used as catalyst and amorphous carbon. Hence it is necessary to purify the soot to obtain pure SWNTs. The biggest problem in purifying APJ-SWNTs is how to remove the thick amorphous carbon covering the catalyst metal particles. By refluxing APJ-SWNTs in hydrogen peroxide using iron particle as catalyst, it can be purified. The added fine particle of pure iron is found to be effective. Then, we examine whether SWNTs can be purified more effectively by adding solution containing the Fe ion instead of the iron particle. We used iron (III) nitrate nonahydrate, hydrogen peroxide decomposing agent which contains catalase and ammonium iron (II) sulfate hexahydrate. In the case of iron (III) nitrate and catalase, purification effect is not obvious. Under these conditions hydrogen peroxide was decomposed into H2O and O2, and the hydroxyl radical was not generated. On the other hand, ammonium iron (II) sulfate is effective. Because of existence of Fe2+ in solution Fenton's reaction takes place. Reaction rate is increased at high temperature. Therefore, APJ-SWNT is purified more effectively if refluxed in hydrogen peroxide using ammonium iron (II) sulfate as catalyst. PMID:20355392

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  3. Polyglycerol-derived amphiphiles for single walled carbon nanotube suspension

    NASA Astrophysics Data System (ADS)

    Setaro, A.; Popeney, C. S.; Trappmann, B.; Datsyuk, V.; Haag, R.; Reich, S.

    2010-06-01

    Inspired by the commercially available SDS surfactant, a new polyglycerol-derived amphiphile has been synthesized for functionalizing carbon nanotubes. SDS' sulphate group was replaced by a polyglycerol dendron. The steric hindrance offered by the dendrons makes the compound much more efficient than SDS in isolating and stabilizing nanotubes in solution. Further amphiphiles have been synthesized by adding small aromatic moieties between head and tail groups. We show that this addition leads to selective interaction between surfactants and carbon nanotubes. Excitation photoluminescence and optical absorption spectroscopy analysis confirm the change in the distribution of nanotubes' chiralities in suspension, depending on the amphiphile.

  4. Tunable assembly of carbon nanospheres on single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Qu, Liangti; Zhang, Han; Zhu, Jia; Dai, Liming

    2010-07-01

    We have developed a process for spontaneous assembly of carbon nanospheres on aligned or nonaligned single-walled carbon nanotubes (SWNTs) by virtue of plasma-enhanced chemical vapor deposition (PECVD). The formation of carbon nanospheres with a uniform size of 30-60 nm is a catalyst-free process and strongly dependent on the applied plasma power and other factors. Both co-deposition and post-deposition approaches have been developed for effective assembly of carbon nanospheres on SWNTs. Furthermore, the method developed here also allows us to tailor the density and size of carbon nanospheres along nanotubes in a controllable way. The heterojunction structure based on different types of carbon demonstrated in this study represents a new hybrid manner for building complex systems which are promising for various applications.

  5. Tunable assembly of carbon nanospheres on single-walled carbon nanotubes.

    PubMed

    Qu, Liangti; Zhang, Han; Zhu, Jia; Dai, Liming

    2010-07-30

    We have developed a process for spontaneous assembly of carbon nanospheres on aligned or nonaligned single-walled carbon nanotubes (SWNTs) by virtue of plasma-enhanced chemical vapor deposition (PECVD). The formation of carbon nanospheres with a uniform size of 30-60 nm is a catalyst-free process and strongly dependent on the applied plasma power and other factors. Both co-deposition and post-deposition approaches have been developed for effective assembly of carbon nanospheres on SWNTs. Furthermore, the method developed here also allows us to tailor the density and size of carbon nanospheres along nanotubes in a controllable way. The heterojunction structure based on different types of carbon demonstrated in this study represents a new hybrid manner for building complex systems which are promising for various applications. PMID:20603535

  6. Resonance Raman Spectroscopy of Single-Wall Carbon Nanotubes Separated via Aqueous Two-Phase Extraction

    NASA Astrophysics Data System (ADS)

    Simpson, J. R.; Fagan, J. A.; Hight Walker, A. R.

    2014-03-01

    We report Resonance Raman Spectroscopy (RRS) measurements of single-wall carbon nanotube (SWCNT) samples dispersed in aqueous solutions via surfactant wrapping and separated using aqueous two-phase extraction (ATPE) into chirality-enriched semiconducting and metallic SWCNT species. ATPE provides a rapid, robust, and remarkably tunable separation technique that allows isolation of high-purity, individual SWCNT chiralities via modification of the surfactant environment. We report RRS measurements of individual SWCNT species of various chiral index including, armchair and zigzag metals. Raman provides a powerful technique to quantify the metallic SWCNTs in ATPE fractions separated for metallicity. We measure Raman spectra over a wide range of excitation wavelengths from 457 nm to 850 nm using a series of discrete and continuously tunable laser sources coupled to a triple-grating spectrometer with a liquid-nitrogen-cooled detector. The spectra reveal Raman-active vibrational modes, including the low-frequency radial breathing mode (RBM) and higher-order modes. SWCNT chiral vectors are determined from the Raman spectra, specifically the RBM frequencies and corresponding energy excitation profiles, together with input from theoretical models.

  7. Resonance Raman Spectroscopy of Single-Wall Carbon Nanotubes Separated via Aqueous Two-Phase Extraction

    NASA Astrophysics Data System (ADS)

    Simpson, J. R.; Fagan, J. A.; Hight Walker, A. R.

    2015-03-01

    We report resonance Raman Spectroscopy measurements of single-wall carbon nanotube (SWCNT) samples dispersed in aqueous solutions via surfactant wrapping and separated using aqueous two-phase extraction (ATPE) into chirality-enriched semiconducting and metallic SWCNT species. ATPE provides a rapid, robust, and remarkably tunable separation technique that allows isolation of high-purity, individual SWCNT chiralities via modification of the surfactant environment. We report RRS measurements of individual SWCNT species of various chiral index including, semiconductors, armchair and zigzag metals. Raman provides a powerful technique to quantify the metallic SWCNTs in ATPE fractions separated for metallicity. We measure Raman spectra over a wide range of excitation wavelengths from (457 to 850) nm using a series of discrete and continuously tunable laser sources coupled to a triple-grating spectrometer. The spectra reveal Raman-active vibrational modes, including the low-frequency radial breathing mode (RBM) and higher-order modes. SWCNT chiral vectors are determined from Raman spectra, specifically the RBM frequencies and corresponding energy excitation profiles, together with input from theoretical models.

  8. Synthesis and Characterization of Single-Wall Carbon Nanotube-Amorphous Diamond Thin-Film Composites

    SciTech Connect

    Schittenhelm, Henrik; Geohegan, David B; Jellison Jr, Gerald Earle; Puretzky, Alexander A; Lance, Michael J; Britt, Phillip F

    2002-01-01

    Thin-film single-wall carbon nanotube (SWNT) composites synthesized by pulsed laser deposition (PLD) are reported. Ultrahard, transparent, pure-carbon, electrically insulating, amorphous diamond thin films were deposited by PLD as scratch-resistant, encapsulating matrices for disperse, electrically conductive mats of SWNT bundles. In situ resistance measurements of the mats during PLD, as well as ex situ Raman spectroscopy, current-voltage measurements, spectroscopic ellipsometry, and field-emission scanning electron microscopy, are used to understand the interaction between the SWNT and the highly energetic ({approx}100 eV) carbon species responsible for the formation of the amorphous diamond thin film. The results indicate that a large fraction of SWNT within the bundles survive the energetic bombardment from the PLD plume, preserving the metallic behavior of the interconnected nanotube mat, although with higher resistance. Amorphous diamond film thicknesses of only 50 nm protect the SWNT against wear, providing scratch hardness up to 25 GPa in an optically transmissive, all-carbon thin-film composite.

  9. Carbon Single-Wall Nanatube Growth in a Volumetrically Confined Arc Discharge System

    SciTech Connect

    Franz, K.J.; Alleman, J.L.; Jones, K.M.; Dillon, A.C.; Heben, M.J.

    2004-01-01

    Carbon nanotubes hold significant promise for a vast number of materials applications due to their unique mechanical, electrical, and gas storage properties. Although carbon single-wall nanotubes (SWNTs) have been synthesized since 1993 by the arc discharge method, and numerous other synthesis methods have since been developed, no method has yet produced 100% pure carbon nanotubes. Instead, a significant amount of impurities—various carbon structures and metal catalysts—are present in the raw soot. While arc discharge was the first method for SWNT synthesis, it also produces more impure raw soot in comparison to the more recently developed laser vaporization, which has produced the purest raw soot to date but is much slower. Geometry and thermal gradient are appreciably different between traditional arc discharge systems and laser vaporization systems. We report that, by incorporating some characteristics inherent to a laser vaporization system into an arc discharge system, improvement in the yield of SWNT raw soot may be achieved. This is accomplished by confining the arc within a 50 mm diameter quartz tube, similar to laser vaporization. We find through transmission electron microscopy and Raman spectroscopy that SWNTs are made in significant numbers in this confined arc discharge system, comparable to laser vaporization synthesized material. Further study is, however, required to prove reproducibility and attain an exact value for the purity of the produced raw soot.

  10. Density functional theory (DFT) study of a new novel bionanosensor hybrid; tryptophan/Pd doped single walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Yoosefian, Mehdi; Etminan, Nazanin

    2016-07-01

    In order to explore a new novel L-amino acid/transition metal doped single walled carbon nanotube based biosensor, density functional theory calculations were studied. These hybrid structures of organic-inorganic nanobiosensors are able to detect the smallest amino acid building block of proteins. The configurations of amine and carbonyl group coordination of tryptophan aromatic amino acid adsorbed on Pd/doped single walled carbon nanotube were compared. The frontier molecular orbital theory, quantum theory atom in molecule and natural bond orbital analysis were performed. The molecular electrostatic potential and the electron density surfaces were constructed. The calculations indicated that the Pd/SWCNT was sensitive to tryptophan suggesting the importance of interaction with biological molecule and potential detecting application. The proposed nanobiosensor represents a highly sensitive detection of protein at ultra-low concentration in diagnosis applications.

  11. Gas detection mechanism for single-walled carbon nanotube networks

    NASA Astrophysics Data System (ADS)

    Boyd, Anthony; Dube, Isha; Fedorov, Georgy; Paranjape, Makarand; Barbara, Paola; Georgetown/RRC Kurchatov Collaboration

    2011-03-01

    We study field-effect transistors fabricated with carbon nanotube (CNT) networks to determine whether the gas sensing mechanism is due to molecules adsorbed on the nanotubes, or changes at the interface between the nanotubes and the contacts. Our previous work showed that in devices made with isolated CNT, the response to nitrogen dioxide was mainly due to the contact interfaces. Here, we focus on CNT networks and use SU-8 layers patterned with e-beam lithography to passivate the contact interfaces, while leaving the network exposed. We look to investigate possible differences in sensing mechanism for devices made with isolated tubes versus networks. Work funded by NSF, DMR 1008242.

  12. Gate-tuned spin to charge conversion in semiconducting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shigematsu, Ei; Nagano, Hiroshi; Dushenko, Sergey; Ando, Yuichiro; Tsuda, Tetsuya; Kuwabata, Susumu; Takenobu, Taishi; Tanaka, Takeshi; Kataura, Hiromichi; Shinjo, Teruya; Shiraishi, Masashi

    Interconversion of spin and charge current is a hot topic in the molecular spintronics. It was achieved for the first time in a conducting conjugated polymer 1, and shortly followed by spin-charge conversion in graphene. However, control over carrier type has not been shown yet. In this study we focused on single-walled carbon nanotubes (SWNT). Spin injection into semiconductor from metal ferromagnet is challenging due to the presence of Schottky barrier and conductance mismatch problem. To bypass it, we used ionic liquid electric gate and ferrimagnetic insulator. We prepared SWNT layer on top of ferrimagnetic yttrium iron garnet substrate. Using spin pumping we successfully observed spin-charge conversion in metallic SWNT. As for a semiconducting SWNT, we applied a top gate using ionic liquid. The drain-source current vs. gate voltage dependence showed tuning of the Fermi level and changing of carrier type. Under gate voltage application we measured electromotive force induced by spin pumping. Detected voltage changed its sign together with carrier type. This is first evidence of spin-charge conversion in carbon nanotubes 2. 1 K. Ando et al., Nature Mater. 12, 622 (2013). 2 E. Shigematsu et al., submitted.

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

    PubMed Central

    Liu, Jian; Li, Guomin

    2013-01-01

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

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

    PubMed

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

    2012-07-01

    Recently, the grafting of polymer chains onto nanotubes has attracted increasing attention as it can potentially be used to enhance the solubility of nanotubes and in the development of novel nanotube-based devices. In this article, based on density functional theory (DFT) calculations, we report the formation of trans-polyacetylene on single-walled carbon-doped boron nitride nanotubes (BNNTs) through their adsorption of a series of C(2)H(2) molecules. The results show that, rather than through [2 + 2] cycloaddition, an individualmolecule would preferentially attach to a carbon-doped BNNT via "carbon attack" (i.e., a carbon in the C(2)H(2) attacks a site on the BNNT). The adsorption energy gradually decreases with increasing tube diameter. The free radical of the carbon-doped BNNT is almost completely transferred to the carbon atom at the end of the adsorbed C(2)H(2) molecule. When another C(2)H(2) molecule approaches the carbon-doped BNNT, it is most energetically favorable for this C(2)H(2) molecule to be adsorbed at the end of the previously adsorbed C(2)H(2) molecule, and so on with extra C(2)H(2) molecules, leading to the formation of polyacetylene on the nanotube. The spin of the whole system is always localized at the tip of the polyacetylene formed, which initiates the adsorption of the incoming species. The present results imply that carbon-doped BNNT is an effective "metal-free" initiator for the formation of polyacetylene. PMID:22271098

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

    SciTech Connect

    Thekkethala, Joe Francis; Sathian, Sarith P.

    2013-11-07

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

  16. Filtration Patterning of Single Walled Carbon Nanotube Films

    NASA Astrophysics Data System (ADS)

    Daly, David A.; Wu, Zhuangchun; Rinzler, Andrew G.

    2006-03-01

    Carbon nanotubes are increasingly being explored for applications exploiting the bulk electrical conductivity of aggregate nanotubes in the form of fibers and films. Attractive in this regard are electrical conductivities orders of magnitude greater than those of conducting polymers, while retaining many of the useful features of polymers, e.g. flexibility, transparency (in thin films) and alternative device fabrication strategies. Here we describe a novel, non-lithographic patterning technique that should also be applicable to other nano-materials. The technique is based on our method for forming thin, pure nanotube films on the surface of a filtration membrane followed by transfer of the film to the desired substrate.^1 To generate patterned films we block the pores of the filtration membrane in the inverse of the ultimately desired film pattern, prior to film formation on the surface of the membrane. The nanotubes only accumulate in the membrane regions that are not occluded, resulting in the desired pattern. Blocking of the membrane pores is accomplished with use of a commercial printer. Implementation and limitations of the technique will be discussed. 1. Z. Wu, Z. Chen, X. Du, J. M. Logan, J. Sippel, M. Nikolou, K. Kamaras, J. R. Reynolds, D. B. Tanner, A. F. Hebard, A. G. Rinzler, Science 305, 1273 (2004).

  17. Influence of Electronic Type Purity on the Lithiation of Single-Walled Carbon Nanotubes

    SciTech Connect

    Jaber-Ansari, Laila; Iddir, Hakim; Curtiss, Larry A.; Hersam, Mark C.

    2014-02-08

    Single-walled carbon nanotubes (SWCNTs) have emerged as one of the leading additives for high-capacity nanocomposite lithium ion battery electrodes due to their ability to improve electrode conductivity, current collection efficiency, and charge/discharge rate for high power applications. However, since as-grown SWCNTs possess a distribution of physical and electronic structures, it is of high interest to determine which subpopulations of SWCNTs possess the highest lithiation capacity and to develop processing methods that can enhance the lithiation capacity of underperforming SWCNT species. Toward this end, SWCNT electronic type purity is controlled via density gradient ultracentrifugation, enabling a systematic study of the lithiation of SWCNTs as a function of metal versus semiconducting content. Experimentally, vacuum-filtered freestanding films of metallic SWCNTs are found to accommodate lithium with an order of magnitude higher capacity than their semiconducting counterparts, which is consistent with ab initio molecular dynamics and density functional theory calculations in the limit of isolated SWCNTs. In contrast, SWCNT film densification leads to the enhancement of the lithiation capacity of semiconducting SWCNTs to levels comparable to metallic SWCNTs, which is corroborated by theoretical calculations that show increased lithiation of semiconducting SWCNTs in the limit of small SWCNT*SWCNT spacing. Overall, these results will inform ongoing efforts to utilize SWCNTs as conductive additives in nanocomposite lithium ion battery electrodes.

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

    SciTech Connect

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

    2014-09-01

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

  19. Direct Synthesis of Single-Walled Carbon Nanotubes on Silicon and Quartz-Based Systems

    NASA Astrophysics Data System (ADS)

    Murakami, Yoichi; Chiashi, Shohei; Miyauchi, Yuhei; Maruyama, Shigeo

    2004-03-01

    A newly developed technique of synthesizing single-walled carbon nanotubes (SWNTs) directly on the surface of Si and quartz substrates is introduced in this report. This technique adopted a liquid-based dip-coating method to mount a very small amount of catalyst metals on the surface of substrates using Mo/Co bimetallic acetate solution. The merits of this approach lie in its easy, costless, and geometry-flexible nature compared with conventional sputtering and deposition approaches. We used the alcohol catalytic chemical vapor deposition (ACCVD) method that can produce relatively high-quality SWNTs even at low temperatures down to 600°C. This low-temperature process contributes to the prevention of the agglomeration of catalytic metals on the surface and chemical reaction between catalytic metal and silicon, which helps us to eliminate any kind of intermediating support materials. Thereby synthesized SWNTs on Si and quartz substrates under various CVD conditions are characterized by means of SEM, TEM, Raman scattering, and optical absorbance measurements. The underlying reasons our experimental procedure and choice of catalyst worked for the synthesis of SWNTs are discussed through comparative studies. At the end of this report, some possible applications of this technique are stated.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  1. Single-walled carbon nanotube growth from ion implanted Fe catalyst

    SciTech Connect

    Choi, Yongho; Sippel-Oakley, Jennifer; Ural, Ant

    2006-10-09

    The authors present experimental evidence that single-walled carbon nanotubes can be grown by chemical vapor deposition from ion implanted iron catalyst. They systematically characterize the effect of ion implantation dose and energy on the catalyst nanoparticles and nanotubes formed at 900 deg. C. They also fabricate a micromachined silicon grid for direct transmission electron microscopy characterization of the as-grown nanotubes. This work opens up the possibility of controlling the origin of single-walled nanotubes at the nanometer scale and of integrating them into nonplanar three-dimensional device structures with precise dose control.

  2. Nanoscale soldering of axially positioned single-walled carbon nanotubes: a molecular dynamics simulation study.

    PubMed

    Cui, Jianlei; Yang, Lijun; Zhou, Liang; Wang, Yang

    2014-02-12

    The miniaturization of electronics devices into the nanometer scale is indispensable for next-generation semi-conductor technology. Carbon nanotubes (CNTs) are considered to be the promising candidates for future interconnection wires. To study the carbon nanotubes interconnection during nanosoldering, the melting process of nanosolder and nanosoldering process between single-walled carbon nanotubes are simulated with molecular dynamics method. As the simulation results, the melting point of 2 nm silver solder is about 605 K because of high surface energy, which is below the melting temperature of Ag bulk material. In the nanosoldering process simulations, Ag atoms may be dragged into the nanotubes to form different connection configuration, which has no apparent relationship with chirality of SWNTs. The length of core filling nanowires structure has the relationship with the diameter, and it does not become longer with the increasing diameter of SWNT. Subsequently, the dominant mechanism of was analyzed. In addition, as the heating temperature and time, respectively, increases, more Ag atoms can enter the SWNTs with longer length of Ag nanowires. And because of the strong metal bonds, less Ag atoms can remain with the tight atomic structures in the gap between SWNT and SWNT. The preferred interconnection configurations can be achieved between SWNT and SWNT in this paper. PMID:24392855

  3. Hydrothermally Oxidized Single-Walled Carbon Nanotube Networks for High Volumetric Electrochemical Energy Storage.

    PubMed

    Liu, Tianyuan; Davijani, Amir A Bakhtiary; Sun, Jingying; Chen, Shuo; Kumar, Satish; Lee, Seung Woo

    2016-07-01

    Improving volumetric energy density is one of the major challenges in nanostructured carbon electrodes for electrochemical energy storage device applications. Herein, a simple hydrothermal oxidation process of single-walled carbon nanotube (SWNT) networks in dilute nitric acid is reported, enabling simultaneous physical densification and chemical functionalization of the as-assembled randomly-packed SWNT films. After the hydrothermal oxidation process, the density of the SWNT films increases from 0.63 to 1.02 g cm(-3) and a considerable amount of redox-active oxygen functional groups are introduced on the surface of the SWNTs. The functionalized SWNT films are used as positive electrodes against Li metal negative electrodes for potential Li-ion capacitors or Li-ion battery applications. The functionalized SWNT electrodes deliver high volumetric as well as gravimetric capacities, 154 Ah L(-1) and 152 mAh g(-1) , respectively, owing to the surface redox reactions between the introduced oxygen functional groups and Li ions. In addition, these electrodes exhibit a remarkable rate-capability by retaining its high capacity of 94 Ah L(-1) (92 mAh g(-1) ) at a high discharge rate of 10 A g(-1) . These results demonstrate the simple hydrothermal oxidation process as an attractive strategy for improving the volumetric performance of nanostructured carbon electrodes. PMID:27200509

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  5. Aqueous-phase synthesis of monodisperse plasmonic gold nanocrystals using shortened single-walled carbon nanotubes.

    PubMed

    Kim, Jin-Woo; Moon, Hyung-Mo; Benamara, Mourad; Sakon, Joshua; Salamo, Gregory J; Zharov, Vladimir P

    2010-10-14

    Monodisperse gold nanocrystals with unique near-infrared optical properties were synthesized by simple mixing of highly shortened and well disperse single-walled carbon nanotubes and chloroauric acid in water at ambient conditions with a step-wise increase of gold ion concentration. PMID:20737105

  6. Chirality sensitive binding of tryptophan enantiomers with pristine single wall carbon nanotubes.

    PubMed

    Bhattacharyya, Tamoghna; Roy, Sarita; Dasgupta, Anjan Kr

    2014-07-28

    We report the differential binding nature of pristine single wall carbon nanotubes (SWNTs) with tryptophan enantiomers. The differential co-operative response between the pristine SWNTs (topologically chiral) and L- and D-tryptophan (geometrically chiral) provides the insight that geometrical chirality itself manifests with topological chirality in a complex way. PMID:24921981

  7. One-step synthesis of fluorescently labelled, single-walled carbon nanotubes.

    PubMed

    Guaragno, Michelle L; Gottardi, Riccardo; Fedorchak, Morgan V; Roy, Abhijit; Kumta, Prashant N; Little, Steven R

    2015-12-18

    Single-walled carbon nanotubes (SWNTs) can be labelled with functional moieties that endow them with a number of unique characteristics, which can be applicable to biomedical applications such as imaging. Herein we describe a facile, one-step esterification process to functionalize SWNT with fluorescein. PMID:26458421

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

    EPA Science Inventory


    Abstract

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

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

  12. Engineered Carbohydrate-Binding Module (CBM) Protein-Suspended Single-Walled Carbon Nanotubes in Water

    SciTech Connect

    Xu,Q.; Song, Q.; Ai, X.; McDonald, T. J.; Long, H.; Ding. S. Y.; Himmel, M. E.; Rumbles, G.

    2009-01-01

    Engineered protein, CtCBM4, the first carbohydrate-binding module (CBM) protein is successfully used to debundle and suspend single-walled carbon nanotubes (SWNTs) effectively in aqueous solution, which opens up a new avenue in further functionalizing and potential selectively fractionating SWNTs for diverse biology- and/or energy-related applications.

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

    DOEpatents

    Hauge, Robert H; Xu, Ya-Qiong

    2013-08-13

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

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

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel

    2009-01-01

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

  15. Nanoscale thermocapillarity enabled purification for horizontally aligned arrays of single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jin, Sung Hun; Dunham, Simon; Xie, Xu; Rogers, John A.

    2015-09-01

    Among the remarkable variety of semiconducting nanomaterials that have been discovered over the past two decades, single-walled carbon nanotubes remain uniquely well suited for applications in high-performance electronics, sensors and other technologies. The most advanced opportunities demand the ability to form perfectly aligned, horizontal arrays of purely semiconducting, chemically pristine carbon nanotubes. Here, we present strategies that offer this capability. Nanoscale thermos-capillary flows in thin-film organic coatings followed by reactive ion etching serve as highly efficient means for selectively removing metallic carbon nanotubes from electronically heterogeneous aligned arrays grown on quartz substrates. The low temperatures and unusual physics associated with this process enable robust, scalable operation, with clear potential for practical use. Especially for the purpose of selective joule heating over only metallic nanotubes, two representative platforms are proposed and confirmed. One is achieved by selective joule heating associated with thin film transistors with partial gate structure. The other is based on a simple, scalable, large-area scheme through microwave irradiation by using micro-strip dipole antennas of low work-function metals. In this study, based on purified semiconducting SWNTs, we demonstrated field effect transistors with mobility (> 1,000 cm2/Vsec) and on/off switching ratio (~10,000) with current outputs in the milliamp range. Furthermore, as one demonstration of the effectiveness over large area-scalability and simplicity, implementing the micro-wave based purification, on large arrays consisting of ~20,000 SWNTs completely removes all of the m-SWNTs (~7,000) to yield a purity of s-SWNTs that corresponds, quantitatively, to at least to 99.9925% and likely significantly higher.

  16. Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Xie, Xu; Jin, Sung Hun; Wahab, Muhammad A.; Islam, Ahmad E.; Zhang, Chenxi; Du, Frank; Seabron, Eric; Lu, Tianjian; Dunham, Simon N.; Cheong, Hou In; Tu, Yen-Chu; Guo, Zhilin; Chung, Ha Uk; Li, Yuhang; Liu, Yuhao; Lee, Jong-Ho; Song, Jizhou; Huang, Yonggang; Alam, Muhammad A.; Wilson, William L.; Rogers, John A.

    2014-11-01

    Recent progress in the field of single-walled carbon nanotubes (SWNTs) significantly enhances the potential for practical use of this remarkable class of material in advanced electronic and sensor devices. One of the most daunting challenges is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here we introduce a simple, scalable, large-area scheme that achieves this goal through microwave irradiation of aligned SWNTs grown on quartz substrates. Microstrip dipole antennas of low work-function metals concentrate the microwaves and selectively couple them into only the metallic SWNTs (m-SWNTs). The result allows for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies of the process. As one demonstration of the effectiveness, implementing this method on large arrays consisting of ~20,000 SWNTs completely removes all of the m-SWNTs (~7,000) to yield a purity of s-SWNTs that corresponds, quantitatively, to at least to 99.9925% and likely significantly higher.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    The thin 50 nm film of bundled arc-discharge single-wall carbon nanotubes was irradiated by femtosecond laser pulses with wavelengths 675, 1350 and 1745 nm corresponding to the absorption band of metallic nanotubes E11M, to the background absorption and to the absorption band of semiconducting nanotubes E11S, respectively. The aim was to induce a selective removal of nanotubes of specific type from the bundled material. Similar to conducted thermal heating experiments, the effect of laser irradiation results in suppression of all radial breathing modes in the Raman spectra, with preferential destruction of the metallic nanotubes with diameters less than 1.26 nm and of the semiconducting nanotubes with diameters 1.36 nm. However, the etching rate of different nanotubes depends on the wavelength of the laser irradiation. It is demonstrated that the relative content of nanotubes of different chiralities can be tuned by a resonant laser ablation of undesired nanotube fraction. The preferential etching of the resonant nanotubes has been shown for laser wavelengths 675 nm (E11M) and 1745 nm (E11S).

  19. Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes.

    PubMed

    Xie, Xu; Jin, Sung Hun; Wahab, Muhammad A; Islam, Ahmad E; Zhang, Chenxi; Du, Frank; Seabron, Eric; Lu, Tianjian; Dunham, Simon N; Cheong, Hou In; Tu, Yen-Chu; Guo, Zhilin; Chung, Ha Uk; Li, Yuhang; Liu, Yuhao; Lee, Jong-Ho; Song, Jizhou; Huang, Yonggang; Alam, Muhammad A; Wilson, William L; Rogers, John A

    2014-01-01

    Recent progress in the field of single-walled carbon nanotubes (SWNTs) significantly enhances the potential for practical use of this remarkable class of material in advanced electronic and sensor devices. One of the most daunting challenges is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here we introduce a simple, scalable, large-area scheme that achieves this goal through microwave irradiation of aligned SWNTs grown on quartz substrates. Microstrip dipole antennas of low work-function metals concentrate the microwaves and selectively couple them into only the metallic SWNTs (m-SWNTs). The result allows for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies of the process. As one demonstration of the effectiveness, implementing this method on large arrays consisting of ~20,000 SWNTs completely removes all of the m-SWNTs (~7,000) to yield a purity of s-SWNTs that corresponds, quantitatively, to at least to 99.9925% and likely significantly higher. PMID:25387684

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

    PubMed

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

    2008-11-01

    Since its invention in 1991, premixed combustion synthesis of fullerenic materials has been established as the major industrial process for manufacturing of these materials. Large-scale production of fullerenes such as C60, C70 and C84 has been implemented. More recently, combustion technology has been extended to the targeted synthesis of single-walled carbon nanotubes (SWCNT). Addition of catalyst precursor and operation at well-controlled fuel-rich but non-sooting conditions are required. Extensive parametric studies have allowed for the optimization of the formation of high-quality SWCNT. Purification techniques previously reported in the literature have been adjusted and used successfully for the nearly complete removal of metal and metal oxide. Material has been characterized using Raman spectroscopy, scanning (SEM) and transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Correlations between process conditions and nanotube properties such as length have been established. Product reproducibility and process scalability of the combustion process have been demonstrated. Sample preparation was found to affect significantly the apparent characteristics of nanotubes as seen in electron microscopy images. PMID:19198347

  1. Pulsed Laser CVD Investigations of Single-Wall Carbon Nanotube Growth Dynamics

    SciTech Connect

    Geohegan, David B; Liu, Zuqin; Styers-Barnett, David J; Puretzky, Alexander A; Rouleau, Christopher M; Yuan, Dongning; Ivanov, Ilia N; Xiao, Kai; Liu, Jie

    2008-01-01

    The nucleation and rapid growth of single-wall carbon nanotubes (SWNTs) were explored by pulsed-laser assisted chemical vapor deposition (PLA-CVD). A special high-power, Nd:YAG laser system with tunable pulse width (> 0.5 ms) was implemented to rapidly heat (>30,000 C/s) metal catalyst-covered substrates to different growth temperatures for very brief (sub-second) and controlled time periods as measured by in situ optical pyrometry. Utilizing growth directly on transmission electron microscopy grids, exclusively SWNTs were found to grow under rapid heating conditions, with a minimum nucleation time of >0.10 s. By measuring the length of nanotubes grown by single laser pulses, extremely fast growth rates (up to 100 microns/s) were found to result from the rapid heating and cooling induced by the laser treatment. Subsequent laser pulses were found not to incrementally continue the growth of these nanotubes, but instead activate previously inactive catalyst nanoparticles to grow new nanotubes. Localized growth of nanotubes with variable density was demonstrated through this process, and was applied for the reliable direct-write synthesis of SWNTs onto pre-patterned, catalyst-covered metal electrodes for the synthesis of SWNT field-effect transistors.

  2. Effect of gelatin on the water dispersion and centrifugal purification of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hanium Maria, Kazi; Mieno, Tetsu

    2016-01-01

    We report a convenient and effective procedure for the water dispersion and purification of single-walled carbon nanotubes (SWNTs). The purification procedure involves a combination of dispersion and centrifugation, in which gelatin; an environmentally friendly material is used as a dispersing agent. It has been found that an aqueous solution of gelatin effectively disperses SWNTs for more than a month. Another advantage of using gelatin as a dispersing agent is that it can be easily removed by washing with water and filtration. The centrifugation procedure employs a centrifugal force of about 2500 times the gravitational force to separate the particles. Although carbonaceous and metallic impurities usually have higher density than SWNTs in arc-produced carbon soot, the centrifugation can easily remove impurities leaving undamaged SWNTs in solution when appropriate centrifugal force and a centrifugation time are used. Centrifugation is carried out for three times to sufficiently remove impurities. Finally, the SWNTs are separated from the gelatin by heating in water and filtering.

  3. Ultra-short, Single-walled Carbon Nanotube Capsules for Diagnostic Imaging and Radiotherapy

    NASA Astrophysics Data System (ADS)

    Matson, Michael Lee

    This thesis is centered on the Gadonanotubes (GNTs), an ultra-high-performance magnetic resonance imaging (MRI) contrast agent material discovered in our laboratories in 2005. The GNTs are a new paradigm in MRI contrast agent design with small clusters of Gd3+ ions within ultra-short carbon nanocapsules (ca. 50 nm) cut from full-length single-walled carbon nanotubes. Here, the factors underlying the performance efficacy of the GNTs have been investigated for the first time by variable-field (-50,000 Oe to 50,000 Oe at 2K) and variable-temperature (2K to RT at 100 Oe) magnetic susceptibility measurements using a Magnetic Property Measurement System (MPMS, based on a SQUID magnetometer). Additionally, experiments focused on the effects of hydroxylation of the GNTs' exterior surface regarding water-solubility are examined. Finally, the use of the GNTs as potential replacements for traditional metal-chelating/sequestering agents is explored. More specifically, the internal Gd3+-ion clusters of the GNTs have been radiolabeled: (1) with 153Gd3+ ions to test Gd3+-ion stability to simulated biological challenge, (2) with 225Ac3+ ions to generate a new concept for a GNT-based agent for alpha-radiotherapy, and finally (3) with 64Cu2+ ions to produce the first bimodal MRI/PET (PET = positron emission tomography) imaging agent derived from the GNTs.

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

    NASA Technical Reports Server (NTRS)

    Hong, Seunghun

    2002-01-01

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

  5. Doping of single-walled carbon nanotubes controlled via chemical transformation of encapsulated nickelocene.

    PubMed

    Kharlamova, Marianna V; Sauer, Markus; Saito, Takeshi; Sato, Yuta; Suenaga, Kazu; Pichler, Thomas; Shiozawa, Hidetsugu

    2015-01-28

    Controlled doping of carbon nanotubes is elemental for their electronic applications. Here we report an approach to tune the polarity and degree of doping of single-walled carbon nanotubes via filling with nickelocene followed by encapsulated reactions. Using Raman, photoemission spectroscopy and transmission electron microscopy, we show that nickelocene molecules transform into nickel carbides, nickel and inner carbon nanotubes with reaction temperatures as low as 250 °C. The doping efficiency is determined for each chemical component. Synchronous charge transfer among the molecular components allows bipolar doping of the carbon nanotubes to be achieved in a broad range of ±0.0012 e(-) per carbon. PMID:25503929

  6. Manifestation of Structure of Electron Bands in Double-Resonant Raman Spectra of Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Stubrov, Yurii; Nikolenko, Andrii; Gubanov, Viktor; Strelchuk, Viktor

    2016-01-01

    Micro-Raman spectra of single-walled carbon nanotubes in the range of two-phonon 2D bands are investigated in detail. The fine structure of two-phonon 2D bands in the low-temperature Raman spectra of the mixture and individual single-walled carbon nanotubes is considered as the reflection of structure of their π-electron zones. The dispersion behavior of 2D band fine structure components in the resonant Raman spectra of single-walled carbon nanotube mixture is studied depending on the energy of excitating photons. The role of incoming and outgoing electron-phonon resonances in the formation of 2D band fine structure in Raman spectra of single-walled carbon nanotubes is analyzed. The similarity of dispersion behavior of 2D phonon bands in single-walled carbon nanotubes, one-layer graphene, and bulk graphite is discussed.

  7. Manifestation of Structure of Electron Bands in Double-Resonant Raman Spectra of Single-Walled Carbon Nanotubes.

    PubMed

    Stubrov, Yurii; Nikolenko, Andrii; Gubanov, Viktor; Strelchuk, Viktor

    2016-12-01

    Micro-Raman spectra of single-walled carbon nanotubes in the range of two-phonon 2D bands are investigated in detail. The fine structure of two-phonon 2D bands in the low-temperature Raman spectra of the mixture and individual single-walled carbon nanotubes is considered as the reflection of structure of their π-electron zones. The dispersion behavior of 2D band fine structure components in the resonant Raman spectra of single-walled carbon nanotube mixture is studied depending on the energy of excitating photons. The role of incoming and outgoing electron-phonon resonances in the formation of 2D band fine structure in Raman spectra of single-walled carbon nanotubes is analyzed. The similarity of dispersion behavior of 2D phonon bands in single-walled carbon nanotubes, one-layer graphene, and bulk graphite is discussed. PMID:26729220

  8. Chirality-specific growth of single-walled carbon nanotubes on solid alloy catalysts.

    PubMed

    Yang, Feng; Wang, Xiao; Zhang, Daqi; Yang, Juan; Luo, Da; Xu, Ziwei; Wei, Jiake; Wang, Jian-Qiang; Xu, Zhi; Peng, Fei; Li, Xuemei; Li, Ruoming; Li, Yilun; Li, Meihui; Bai, Xuedong; Ding, Feng; Li, Yan

    2014-06-26

    Carbon nanotubes have many material properties that make them attractive for applications. In the context of nanoelectronics, interest has focused on single-walled carbon nanotubes (SWNTs) because slight changes in tube diameter and wrapping angle, defined by the chirality indices (n, m), will shift their electrical conductivity from one characteristic of a metallic state to one characteristic of a semiconducting state, and will also change the bandgap. However, this structure-function relationship can be fully exploited only with structurally pure SWNTs. Solution-based separation methods yield tubes within a narrow structure range, but the ultimate goal of producing just one type of SWNT by controlling its structure during growth has proved to be a considerable challenge over the last two decades. Such efforts aim to optimize the composition or shape of the catalyst particles that are used in the chemical vapour deposition synthesis process to decompose the carbon feedstock and influence SWNT nucleation and growth. This approach resulted in the highest reported proportion, 55 per cent, of single-chirality SWNTs in an as-grown sample. Here we show that SWNTs of a single chirality, (12, 6), can be produced directly with an abundance higher than 92 per cent when using tungsten-based bimetallic alloy nanocrystals as catalysts. These, unlike other catalysts used so far, have such high melting points that they maintain their crystalline structure during the chemical vapour deposition process. This feature seems crucial because experiment and simulation both suggest that the highly selective growth of (12, 6) SWNTs is the result of a good structural match between the carbon atom arrangement around the nanotube circumference and the arrangement of the catalytically active atoms in one of the planes of the nanocrystal catalyst. We anticipate that using high-melting-point alloy nanocrystals with optimized structures as catalysts paves the way for total chirality

  9. Effect of Different Carbon Sources on the Growth of Single-Walled Carbon Nanotube from MCM-41 Containing Nickel

    SciTech Connect

    Chen,Y.; Wang, B.; Li, L.; Yang, Y.; Ciuparu, D.; Lim, S.; Haller, G.; Pfefferle, L.

    2007-01-01

    Chemical vapor deposition growth of single-walled carbon nanotubes (SWCNTs) was studied using three representative carbon source sources: CO, ethanol, and methane, and a catalyst of Ni ions incorporated in MCM-41. The resulting SWCNTs were compared for similar reaction conditions. Carbon deposits were analyzed by multi-excitation wavelength Raman, TGA, TEM and AFM. Catalytic particles in the Ni-MCM-41 catalysts were characterized by TEM and synchrotron light source X-ray absorption spectroscopy. Under similar synthesis conditions, SWCNTs produced from CO had a relatively smaller diameter, while those from ethanol had a larger diameter. Methane could not produce SWCNTs on Ni-MCM-41 under the conditions used in this research. These results demonstrate that three carbon sources affect the dynamic balances between metallic cluster formation and carbon deposition/precipitation on the metallic cluster surface. Controlling SWCNT diameter relies on precisely regulating this dynamic process. Using different carbon sources we are able to shift this dynamic balance and produce SWCNTs with different mean diameters.

  10. Selective Synthesis of Subnanometer Diameter Semiconducting Single-Walled Carbon Nanotubes

    SciTech Connect

    Loebick, C.; Podila, R; Reppert, J; Chudow, J; Ren, F; Haller, G; Rao, A; Pfefferle, L

    2010-01-01

    Subnanometer single-walled carbon nanotubes (sub-nm SWNTs) were synthesized at different temperatures (600, 700, and 800 C) using CoMn bimetallic catalysts supported on MCM-41 silica templates. The state of the catalyst was investigated using X-ray absorption, and the (n,m) indices of the sub-nm SWNTs were determined from Raman spectroscopy and photoluminescence measurements. We find that the size of the metallic particles that seed the growth of sub-nm SWNTs (diameter {approx}0.5-1.0 nm) is highly sensitive to the reaction temperature. Low reaction temperature (600 C) favors the growth of semiconducting tubes whose diameters range from 0.5 to 0.7 nm. These results were also confirmed by electrical transport measurements. Interestingly, dominant intermediate frequency modes on the same intensity scale as the Raman breathing modes were observed. An unusual 'S-like' dispersion of the G-band was present in the Raman spectra of sub-nm SWNTs with diameters <0.7 nm.

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

    PubMed

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

    2016-04-26

    We report the synthesis and catalytic properties of single-walled carbon nanotube-polyamidoamine dendrimers hybrids (SWCNT-PAMAM), prepared via a convergent strategy. The direct reaction of cystamine-based PAMAM dendrimers (generations 2.5 and 3.0) with pristine SWCNTs in refluxing toluene, followed by immobilization and reduction of [PdCl4](2-), led to the formation of highly dispersed small palladium nanoparticles homogeneously confined throughout the nanotube length. One of these functional materials proved to be an efficient catalyst in Suzuki and Heck reactions, able to promote the above processes down to 0.002 mol % showing a turnover number (TON) of 48 000 and a turnover frequency (TOF) of 566 000 h(-1). In addition, the hybrid material could be recovered and recycled for up to 6 times. No leaching of the metal has been detected during the Suzuki coupling. Additional experiments carried out on the spent catalyst permitted to suggest that a "release and catch" mechanism is operative in both reactions, although during Heck reaction small catalytically active soluble Pd species are also present. PMID:26974262

  12. Two photon polymerization lithography for 3D microfabrication of single wall carbon nanotube/polymer composites

    NASA Astrophysics Data System (ADS)

    Ushiba, Shota; Shoji, Satoru; Kuray, Preeya; Masui, Kyoko; Kono, Junichiro; Kawata, Satoshi

    2013-03-01

    Two photon polymerization (TPP) lithography has been established as a powerful tool to develop 3D fine structures of polymer materials, opening up a wide range applications such as micro-electromechanical systems (MEMS). TPP lithography is also promising for 3D micro fabrication of nanocomposites embedded with nanomaterials such as metal nanoparticles. Here, we make use of TPP lithography to fabricate 3D micro structural single wall carbon nanotube (SWCNT)/polymer composites. SWCNTs exhibit remarkable mechanical, electrical, thermal and optical properties, which leads to enhance performances of polymers by loading SWCNTs. SWCNTs were uniformly dispersed in an acrylate UV-curable monomer including a few amounts of photo-initiator and photo-sensitizer. A femtosecond pulsed laser emitting at 780 nm was focused onto the resin, resulting in the photo-polymerization of a nanometric volume of the resin through TPP. By scanning the focus spot three dimensionally, arbitrary 3D structures were created. The spatial resolution of the fabrication was sub-micrometer, and SWCNTs were embedded in the sub-micro sized structures. The fabrication technique enables one to fabricate 3D micro structural SWCNT/polymer composites into desired shapes, and thus the technique should open up the further applications of SWCNT/polymer composites such as micro sized photomechanical actuators.

  13. Uncovering the ultimate performance of single-walled carbon nanotube films as transparent conductors

    NASA Astrophysics Data System (ADS)

    Mustonen, K.; Laiho, P.; Kaskela, A.; Susi, T.; Nasibulin, A. G.; Kauppinen, E. I.

    2015-10-01

    The ultimate performance—ratio of electrical conductivity to optical absorbance—of single-walled carbon nanotube (SWCNT) transparent conductive films (TCFs) is an issue of considerable application relevance. Here, we present direct experimental evidence that SWCNT bundling is detrimental for their performance. We combine floating catalyst synthesis of non-bundled, high-quality SWCNTs with an aggregation chamber, in which bundles with mean diameters ranging from 1.38 to 2.90 nm are formed from identical 3 μm long SWCNTs. The as-deposited TCFs from 1.38 nm bundles showed sheet resistances of 310 Ω/□ at 90% transparency, while those from larger bundles of 1.80 and 2.90 nm only reached values of 475 and 670 Ω/□, respectively. Based on these observations, we elucidate how networks formed by smaller bundles perform better due to their greater interconnectivity at a given optical density. Finally, we present a semi-empirical model for TCF performance as a function of SWCNT mean length and bundle diameter. This gives an estimate for the ultimate performance of non-doped, random network mixed-metallicity SWCNT TCFs at ˜80 Ω/□ and 90% transparency.

  14. Universal response of single-wall carbon nanotubes to radial compression: theory and experiment

    NASA Astrophysics Data System (ADS)

    Chacham, Helio; Barboza, Ana Paula M.; Neves, Bernardo R. A.

    2009-03-01

    Since the early 90's, the electronic and structural properties of single-wall carbon nanotubes (SWNTs) have been thoroughly investigated. Regarding SWNT mechanical properties, most of the attention has been given to their large resistance to axial tension, even though several electromechanical effects have been observed on radially compressed SWNTs, such as the predicted [1], and recently observed [2], metal-insulator transition. The present work brings a unifying picture to the process of radial compression/deformation of SWNTs, where experimental data are analyzed through a rescaling model yielding a universal-type behavior. Specifically, our AFM measurements show that the quantity Fd^3/2(2R)-1/2, where F is the force applied by the AFM tip (with radius R) and d is the SWNT diameter, is a universal function of the compressive strain. Such universality is reproduced analytically in a model where the graphene bending modulus is the only fitting parameter. The application of the same model to the radial Young modulus Er leads to a further universal-type behavior that explains the large variations of the SWNTs Er reported in the literature. [1] M. S. C. Mazzoni and H. Chacham, Appl. Phys. Lett. 76, 1561 (2000). [2] A. P. M. Barboza et al., Phys. Rev. Lett. 100, 256804 (2008).

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

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram

    2003-01-01

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

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

    DOE PAGESBeta

    Upadhyayula, Venkata K. K.; Ghoshroy, Soumitra; Nair, Vinod S.; Smith, Geoffrey B.; Mitchell, Martha C.; Deng, Shuguang

    2008-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Farhart, Samir; Scott, Carl D.

    2000-01-01

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

  18. Electron backscattering on single-wall carbon nanotubes observed by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Clauss, W.; Bergeron, D. J.; Freitag, M.; Kane, C. L.; Mele, E. J.; Johnson, A. T.

    1999-09-01

    Single-wall carbon nanotubes, seamless cylindrical molecules formed from a graphene sheet, are either conducting or semiconducting, depending on the particular "wrapping vector" that defines the waist of the tube. Scanning tunneling microscopy experiments have tested this idea by simultaneously measuring a tube's lattice structure and electronic properties. Here we present a series of STM images of single-wall carbon nanotubes with a strikingly rich set of superstructures. The observed patterns can be understood as due to interference between propagating electron waves that are reflected from defects on the tube walls and ends, or as intrinsic to states propagating on semiconducting tubes. The measured broken symmetries can be used to directly probe electronic backscattering on the tube and provide a key element in the understanding of low-energy electron transport on these structures.

  19. A black body absorber from vertically aligned single-walled carbon nanotubes

    PubMed Central

    Mizuno, Kohei; Ishii, Juntaro; Kishida, Hideo; Hayamizu, Yuhei; Yasuda, Satoshi; Futaba, Don N.; Yumura, Motoo; Hata, Kenji

    2009-01-01

    Among all known materials, we found that a forest of vertically aligned single-walled carbon nanotubes behaves most similarly to a black body, a theoretical material that absorbs all incident light. A requirement for an object to behave as a black body is to perfectly absorb light of all wavelengths. This important feature has not been observed for real materials because materials intrinsically have specific absorption bands because of their structure and composition. We found a material that can absorb light almost perfectly across a very wide spectral range (0.2–200 μm). We attribute this black body behavior to stem from the sparseness and imperfect alignment of the vertical single-walled carbon nanotubes. PMID:19339498

  20. Regular chemisorption of hydrogen on achiral single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bogdanova, D. A.; Bulyarskii, S. V.

    2016-07-01

    Regular chemisorption of hydrogen on achiral single-walled carbon nanotubes has been investigated with the use of AM1 quantum-chemical semiempirical method. It has been found that regular hydrogen chemisorption deforms nanotubes, in some cases leading to stable prismatic modifications. The dependence of the adsorption energy on the density of hydrogen coverage has been found. A procedure for determining the adsorption energy by the spectra of thermally stimulated desorption has been proposed.

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

    DOE PAGESBeta

    Márquez, Francisco; López, Vicente; Morant, Carmen; Roque-Malherbe, Rolando; Domingo, Concepción; Elizalde, Eduardo; Zamora, Félix

    2010-01-01

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

  2. Wrinkling and strain softening in single-wall carbon nanotube membranes.

    PubMed

    Hobbie, E K; Simien, D O; Fagan, J A; Huh, J Y; Chung, J Y; Hudson, S D; Obrzut, J; Douglas, J F; Stafford, C M

    2010-03-26

    The nonlinear elasticity of thin supported membranes assembled from length purified single-wall carbon nanotubes is analyzed through the wrinkling instability that develops under uniaxial compression. In contrast with thin polymer films, pristine nanotube membranes exhibit strong softening under finite strain associated with bond slip and network fracture. We model the response as a shift in percolation threshold generated by strain-induced nanotube alignment in accordance with theoretical predictions. PMID:20366547

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

    SciTech Connect

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

    2010-01-01

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

  4. Transport properties of a potassium-doped single-wall carbon nanotube rope

    SciTech Connect

    Lee, R. S.; Kim, H. J.; Fischer, J. E.; Lefebvre, J.; Radosavljevic, M.; Hone, J.; Johnson, A. T.

    2000-02-15

    Four-probe resistance vs temperature and gate voltage are reported for an individual single-wall carbon nanotube rope before and after doping in situ with potassium. All the features in R(T) from unoriented bulk material, before and after doping, are qualitatively reproduced by the rope data. The 5.3 K conductance of the pristine rope decreases with positive gate voltage, while G vs V{sub g} becomes featureless after K doping. (c) 2000 The American Physical Society.

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

    SciTech Connect

    Mitchell,C.; Krishnamoorti, R.

    2007-01-01

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

  6. Tutorial: Linear surface conductivity of an achiral single-wall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Nemilentsau, Andrei M.

    2011-01-01

    Theoretical consideration of electromagnetic scattering by single-wall carbon nanotubes (SWNTs) and SWNT arrays requires knowledge of the linear surface conductivity of an SWNT. An expression for the surface conductivity of an infinitely long SWNT was derived by Slepyan et al. [Phys. Rev. B 60, 17136-17149 (1999)]. The twin purposes of this tutorial are to succinctly discuss the derivation using the density matrix formalism and to provide ready-to-use expressions.

  7. Below-gap excitation of semiconducting single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Soavi, G.; Grupp, A.; Budweg, A.; Scotognella, F.; Hefner, T.; Hertel, T.; Lanzani, G.; Leitenstorfer, A.; Cerullo, G.; Brida, D.

    2015-10-01

    We investigate the optoelectronic properties of the semiconducting (6,5) species of single-walled carbon nanotubes by measuring ultrafast transient transmission changes with 20 fs time resolution. We demonstrate that photons with energy below the lowest exciton resonance efficiently lead to linear excitation of electronic states. This finding challenges the established picture of a vanishing optical absorption below the fundamental excitonic resonance. Our result points towards below-gap electronic states as an intrinsic property of semiconducting nanotubes.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  9. Preferential syntheses of semiconducting vertically aligned single-walled carbon nanotubes for direct use in FETs.

    PubMed

    Qu, Liangti; Du, Feng; Dai, Liming

    2008-09-01

    We have combined fast heating with plasma enhanced chemical vapor deposition (PECVD) for preferential growth of semiconducting vertically aligned single-walled carbon nanotubes (VA-SWNTs). Raman spectroscopic estimation indicated a high yield of up to 96% semiconducting SWNTs in the VA-SWNT array. The as-synthesized semiconducting SWNTs can be used directly for fabricating FET devices without the need for any postsynthesis purification or separation. PMID:18665651

  10. Atomic layer deposition on suspended single-walled carbon nanotubes via gas-phase noncovalent functionalization.

    PubMed

    Farmer, Damon B; Gordon, Roy G

    2006-04-01

    Alternating exposures of nitrogen dioxide gas and trimethylaluminum vapor are shown to functionalize the surfaces of single-walled carbon nanotubes with a self-limited monolayer. Functionalized nanotube surfaces are susceptible to atomic layer deposition of continuous, radially isotropic material. This allows for the creation of coaxial nanotube structures of multiple materials with precisely controlled diameters. Functionalization involves only weak physical bonding, avoiding covalent modification, which should preserve the unique optical, electrical, and mechanical properties of the nanotubes. PMID:16608267

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  12. Observation of elastic deformations in single-walled carbon nanotubes by Scanning Tunneling Microscopy

    SciTech Connect

    Clauss, Wilfried; Bergeron, David J.; Johnson, Alan T.

    1998-08-11

    Scanning Tunneling Microscopy is used to obtain atomically resolved images of single-walled carbon nanotubes, in ropes of several tens to hundreds of tubes. The images confirm that in this environment strong elastic deformations of the tube lattice occur frequently. In particular, bent and twisted tubes have been identified. The observed distortions could play an important role in explaining the electronic transport properties of nanotubes.

  13. Chirality-dependent boron-mediated growth of nitrogen-doped single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wiltshire, Joseph G.; Li, Lain-Jong; Herz, Laura M.; Nicholas, Robin J.; Glerup, Marianne; Sauvajol, Jean-Louis; Khlobystov, Andrei N.

    2005-11-01

    A change in the relative abundance of single-walled carbon nanotubes, due to the presence of both nitrogen and boron during synthesis, has been identified through Raman and absorption spectroscopy. Raman spectroscopy shows that for two specific branches boron mediates the growth of smaller-diameter zigzag or near-zigzag nanotubes. We combine our experimental results with an improved Kataura model to identify two of the preferentially grown species as (16,0) and (14,1).

  14. Virus sensor based on single-walled carbon nanotube: improved theory incorporating surface effects.

    PubMed

    Elishakoff, Isaac; Challamel, Noël; Soret, Clément; Bekel, Yannis; Gomez, Thomas

    2013-06-28

    In this paper, we deal with the theoretical framework for a single-walled carbon nanotube serving as a virus or bacterium sensor, with the complicating influences of non-locality and surface effects taken into account. It is demonstrated that these effects are not negligible as is often assumed in the literature; they may greatly influence both the vibration behaviour as well as the identification process of the virus or bacterium. PMID:23690635

  15. Intense photoluminescence from dried double-stranded DNA and single-walled carbon nanotube hybrid

    SciTech Connect

    Ito, M.; Kobayashi, T.; Ito, Y.; Hayashida, T.; Nii, D.; Umemura, K.; Homma, Y.

    2014-01-27

    Semiconducting single-walled carbon nanotubes (SWNTs) show near-infrared photoluminescence (PL) when they are individually isolated. This was an obstacle to use photonic properties of SWNTs on a solid surface. We show that SWNTs wrapped with DNA maintain intense PL under the dry conditions. SWNTs are well isolated individually by DNA even when the DNA-SWNT hybrids are agglomerated. This finding opens up application of SWNTs to photonic devices.

  16. Conductivity of Thin Films Based on Single-Walled Carbon Nanotubes Grown by Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Rybakov, M. S.; Kosobutsky, A. V.; Sevostyanov, O. G.; Russakov, D. M.; Lomakin, M. V.; Chirkova, I. M.; Shandakov, S. D.

    2015-03-01

    Electrical and optical properties of thin films of single-walled carbon nanotubes (SWCNT) obtained by aerosol chemical vapor deposition using ethanol, ferrocene, and sulfur are studied. Structural and geometrical characteristics of the synthesis products are determined by the methods of Raman spectroscopy and transmission electron microscopy. The effect of sulfur on the properties of the SWCNTs and thin films based on them is found.

  17. A triple quantum dot in a single-wall carbon nanotube.

    PubMed

    Grove-Rasmussen, K; Jørgensen, H I; Hayashi, T; Lindelof, P E; Fujisawa, T

    2008-04-01

    A top-gated single-wall carbon nanotube is used to define three coupled quantum dots in series between two electrodes. The additional electron number on each quantum dot is controlled by top-gate voltages allowing for current measurements of single, double, and triple quantum dot stability diagrams. Simulations using a capacitor model including tunnel coupling between neighboring dots captures the observed behavior with good agreement. Furthermore, anticrossings between indirectly coupled levels and higher order cotunneling are discussed. PMID:18314966

  18. Single-walled carbon nanotubes synthesis: a direct comparison of laser ablation and carbon arc routes.

    PubMed

    Bystrzejewski, M; Rümmeli, M H; Lange, H; Huczko, A; Baranowski, P; Gemming, T; Pichler, T

    2008-11-01

    Carbon arc and chemical vapor deposition are at present the most efficient methods for mass production of single-walled carbon nanotubes. However, laser ablation is renowned for high quality nanotubes with narrow diameter distributions and hence is also of great interest. The aim of this work was to compare both the carbon arc and laser ablation techniques with respect to the quality--and relative yield of the produced SWCNTs. For this comparative study we used Fe as the catalyst, which is known not to be very active in laser ablation. However, we show this is not the case when H2 is included in the reaction. The reactions for both synthesis routes were carried out in a N2-H2 (95-5% vol.) atmosphere. The same homogenous carbon rods with different iron contents, between 1 and 5 at.% were used as the carbon feedstock and catalyst supply in both synthesis routes. Additionally, two types of carbon rods containing 1 at.% Fe with different graphitization degrees were also investigated. In the arc-discharge case, the low-graphitized electrode produced a web-like product rich in SWCNTs, while the high-graphitized carbon rods yielded soot containing carbon-encapsulated iron nanocrystallites, amorphous carbon nanoparticles, and surprisingly a small fraction of SWCNTs. With laser ablation synthesis, the Fe content and the reactor temperature significantly influenced the SWCNTs yield. Carbon arc plasma diagnostics were also performed. By using optical emission and Absorption spectroscopy the plasma temperature, C2 and CN radical content in the arc zone were determined. PMID:19198361

  19. Molecular simulation of hydrogen adsorption in single-walled carbon nanotubes and idealized carbon slit pores

    NASA Astrophysics Data System (ADS)

    Wang, Qinyu; Johnson, J. Karl

    1999-01-01

    The adsorption of hydrogen gas into single-walled carbon nanotubes (SWNTs) and idealized carbon slit pores is studied by computer simulation. Hydrogen-hydrogen interactions are modeled with the Silvera-Goldman potential. The Crowell-Brown potential is used to model the hydrogen-carbon interactions. Calculations include adsorption inside the tubes, in the interstitial regions of tube arrays, and on the outside surface of isolated tubes. Quantum effects are included through implementation of the path integral formalism. Comparison with classical simulations gives an indication of the importance of quantum effects for hydrogen adsorption. Quantum effects are important even at 298 K for adsorption in tube interstices. We compare our simulations with experimental data for SWNTs, graphitic nanofibers, and activated carbon. Adsorption isotherms from simulations are in reasonable agreement with experimental data for activated carbon, but do not confirm the large uptake reported for SWNTs and nanofibers. Although the adsorption potential for hydrogen in SWNTs is enhanced relative to slit pores of the same size, our calculations show that the storage capacity of an array of tubes is less than that for idealized slit pore geometries, except at very low pressures. Ambient temperature isotherms indicate that an array of nanotubes is not a suitable sorbent material for achieving DOE targets for vehicular hydrogen storage.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  1. High-power supercapacitor electrodes from single-walled carbon nanohorn/nanotube composite.

    PubMed

    Izadi-Najafabadi, Ali; Yamada, Takeo; Futaba, Don N; Yudasaka, Masako; Takagi, Hideyuki; Hatori, Hiroaki; Iijima, Sumio; Hata, Kenji

    2011-02-22

    A novel composite is presented as a supercapacitor electrode with a high maximum power rating (990 kW/kg; 396 kW/l) exceeding power performances of other electrodes. The high-power capability of the electrode stemmed from its unique meso-macro pore structure engineered through the utilization of single-walled carbon nanotubes (20 wt %) as scaffolding for single-walled carbon nanohorns (80 wt %). The novel composite electrode also exhibited durable operation (6.5% decline in capacitance over 100 000 cycles) as a result of its monolithic chemical composition and mechanical stability. The novel composite electrode was benchmarked against another high-power electrode made from single-walled carbon nanotubes (Bucky paper electrode). While the composite electrode had a lower surface area compared to the Bucky paper electrode (280 vs 470 m(2)/g from nitrogen adsorption), it had a higher meso-macro pore volume (2.6 vs 1.6 mL/g from mercury porosimetry) which enabled the composite electrode to retain more electrolyte, ensuring facile ion transport, hence achieving a higher maximum power rating (970 vs 400 kW/kg). PMID:21210712

  2. Electronically Pure Single-Chirality Semiconducting Single-Walled Carbon Nanotube for Large-Scale Electronic Devices.

    PubMed

    Li, Huaping; Liu, Hongyu; Tang, Yifan; Guo, Wenmin; Zhou, Lili; Smolinski, Nina

    2016-08-17

    Single-walled carbon nanotube (SWCNT) networks deposited from a purple single chirality (6,5) SWCNT aqueous solution were electrically characterized as pure semiconductors based on metal/semiconductor/metal Schottky contacts using both complex instruments and a portable device. Both air-stable PMOS (p-type metal-oxide-semiconductor) and NMOS (n-type metal-oxide-semiconductor, resembling amorphous silicon) thin film transistors were fabricated on (6,5) SWCNT in large scale showing the characteristics of fA off current and ION/IOFF ratio of >1 × 10(8). CMOS (complementary metal-oxide-semiconductor) SWCNT inverter was demonstrated by wire-bonding PMOS (6,5) SWCNT TFT and NMOS (6,5) SWCNT TFT together to achieve the voltage gain as large as 52. PMID:27487382

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  4. Anchoring Pd nanoclusters onto pristine and functionalized single-wall carbon nanotubes: A combined DFT and experimental study

    NASA Astrophysics Data System (ADS)

    Prasomsri, Teerawit; Shi, Dachuan; Resasco, Daniel E.

    2010-09-01

    The dispersion of Pd nanoclusters on single-wall carbon nanotubes (SWCNT) can be enhanced by creating defects on the nanotube walls, which lead to a stronger metal-support interaction. The ONIOM (DFT:MM) calculations show that the binding energy of Pd is significantly enhanced when the SWCNT surface is oxygen-functionalized, compared to the case of the pristine SWCNT surface. The electronic interaction of Pd atoms with oxygen at the defect sites results in a stronger bonding. These calculations are consistent with experimental measurements. Microscopy images clearly show that the functionalized SWCNT surface is much more effective than the pristine surface in anchoring Pd nanoclusters.

  5. Single Walled Carbon Nanohorns as Catalytic Counter Electrodes for Co(III)/(II) Electron Mediators in Dye Sensitized Cells.

    PubMed

    Carli, Stefano; Casarin, Laura; Syrgiannis, Zois; Boaretto, Rita; Benazzi, Elisabetta; Caramori, Stefano; Prato, Maurizio; Bignozzi, Carlo Alberto

    2016-06-15

    The electrochemical properties of both pristine single walled carbon nanohorns (SWCNHS) and their chemically oxidized form (ox-SWCNHS) spray coated onto fluorine doped SnO2 (FTO) were investigated in the framework of the fabrication of cobalt based transparent dye sensitized solar cells (DSSCs). These new nanocarbon substrates, evaluated in conjunction with the Co(bpy)3(2+/3+) (bpy = 2,2'-bipyridine) redox mediator, are endowed with excellent electrocatalytic properties, ease of fabrication, and very promising stability and display a great potential for replacing the best noble metal and conductive polymer catalytic materials in the building of semitransparent counter electrodes in new generation photoelectrochemical devices. PMID:27227738

  6. Influence of nanoparticle size to the electrical properties of naphthalenediimide on single-walled carbon nanotube wiring

    NASA Astrophysics Data System (ADS)

    Tanaka, Hirofumi; Hong, Liu; Fukumori, Minoru; Negishi, Ryota; Kobayashi, Yoshihiro; Tanaka, Daisuke; Ogawa, Takuji

    2012-06-01

    Nanoparticles of N,N‧-bis(n-alkyl)tetracarbonatenaphthalenediimide (NDI) were adsorbed on single-walled carbon nanotube (SWNT) wires dispersed on a SiO2 substrate. The electrical properties were measured along the long axis of the SWNTs, and in all cases through the nanoparticles showed rectification in semiconducting I-V curve. The plateau width of the I-V curve through the NDI nanoparticles on metallic SWNTs decreased as the particle size increased, while the rectification ratio increased. The conduction mechanism was changed from tunneling conduction to Schottky-like conduction and their boundary is at about 3 nm diameter.

  7. Flavin-derived self-organization and chirality separation of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ju, Sang-Yong

    2008-07-01

    Formed by rolling up a two-dimensional sheet of one or more layer of graphite, graphene, carbon nanotubes (SWNTs) are the marvel materials of modern materials science. They are phenomenally strong and stiff, and have the unusual property of being excellent conductors of heat along the tube's axis, but good thermal insulators across it. But it is their electrical characteristics that excite the most interest. Especially, single-walled carbon nanotube (SWNTs), formed by one layer of cylindrical graphene, has better physical properties over multi-walled carbon nanotubes (MWNTs) having over two layer of graphene. Depending on the precise way they are rolled up, which is defined by ( n,m) vector, SWNTs can be made into either metals or semiconductors. So far, SWNTs can generally only be fabricated in batches that vary widely, both in the diameter of the individual tubes and in the orientation of their graphene lattice relative to the tube axis, the property known as chirality. Separating out these various conformations is a challenging, but one that must be solved if nanotubes are ever to fulfill their electrifying potential in devices. This thesis presents that flavin-based helical self-assembly can impart multi degrees of SWNTs separation (i.e., metallicity, diameter, chirality, and handedness). As opening chapters for carbon nanotube and flavin derivative, Chapter 1 provide the introduction of carbon nanotubes, especially single-walled tubes, and the current state-of-the-art nanotube separation. Also, Chapter 1 presents a variety of naturally-occurring flavin derivatives, their redox behavior, and their biological utilization as cofactors for various proteins. Motivated by chemoluminescence of flavin mononucleotide (FMN, phosphorylated form of Vitamin B2) with bacterial luciferase, Chapter 2 discuss about the synthesis and covalent attachment of flavin mononucleotide (FMN, phosphorylated form of Vitamin B2) analogue to oxidized SWNTs. Along with nine step synthesis

  8. Raman imaging and spectroscopy of individual single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhang, Li

    Single-wall carbon nanotubes (SWNT) are unique one-dimensional materials that are promising for many potential applications in various important areas. Their vibrational properties reflect the electron and phonon confinement as well as the structures of the tubes. Resonant Raman spectroscopy has been proven to be an exceedingly powerful tool for the characterization of the vibrational and electronic properties of SWNTs. This thesis focuses on the study of Raman spectroscopy of individual single carbon nanotubes. Single tube spectroscopy allows probing the structure dependent properties of SWNTs. A beam-scanning confocal Raman microscope system capable of large-area Raman imaging is first developed for characterizing SWNTs at the single tube level. Raman images and first-order Raman spectra of nanotubes, consisting of both semicoducting and metallic nanotubes, are systemically studied at room temperature in ambient air. The diameter of the nanotubes is determined from their radial breathing mode (RBM) frequency. A broad diameter distribution is observed for nanotubes synthesized by chemical vapor deposition. The tangential G mode Raman spectra of individual metallic nanotubes are found to exhibit a broad distribution of line shapes, which is attributed to shift of the Fermi level due to O2 adsorption. The doping dependence of Raman spectra of metallic tubes is further studied by both electrostatic gating and electrochemical gating. Significant changes in the G band Raman spectra of nanotubes are observed, suggesting the effect of doping on electron-phonon interaction. The observation of a gradual evolution of G band spectrum from a semiconducting type to the broad BWF type reveals evidence of phonon interaction between two G band modes. Raman imaging and Raman spectra of isolated SWNTs and single-layer graphenen are investigated at both room temperature and low temperature. The temperature-induced Raman spectral change of individual nanotubes is observed to be tube

  9. 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...

  10. Surface chemical functionalized single-walled carbon nanotube with anchored phenol structures: Physical and chemical characterization

    NASA Astrophysics Data System (ADS)

    Bae, Jong Hyun; Shanmugharaj, A. M.; Noh, Woo Hyun; Choi, Won Seok; Ryu, Sung Hun

    2007-02-01

    Surface functionalization of single-walled carbon nanotube was carried out by introducing ylides groups containing anchored phenol structures. The functionalized nanotube is characterized using elemental analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis, Raman spectroscopy and zeta potential measurements. Elemental and FT-IR analysis reveal the successful functionalization of azomethine ylides. Raman spectroscopic studies corroborates that the surface functionalization does not affect the basic crystal domain size of the nanotubes. Functionalized carbon nanotubes exhibit higher zeta potential values showing its higher dispersant ability in water and acetone solvent in comparison to pure carbon nanotube.

  11. Nano-Plasticity of Single-Wall Carbon Nanotubes Under Uniaxial Compression

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Menon, Madu; Cho, Kyeongjae

    1999-01-01

    Nano-plasticity of thin single-wall carbon nanotubes under uniaxial compression is investigated through generalized tight-binding molecular dynamics (GTBMD) and ab-initio electronic structure methods. A novel mechanism of nano-plasticity of carbon nanotubes under uniaxial compression is observed in which bonding geometry collapses from a graphitic (sp(sup 2)) to a localized diamond like (sp(sup 3)) reconstruction. The computed critical stress (approximately equals 153 G Pa) and the shape of the resulting plastic deformation is in good agreement with recent experimental observation of collapse and fracture of compressed carbon nanotubes in polymer composites.

  12. Practical considerations for the demonstration of a single walled carbon nanotube actuator

    NASA Astrophysics Data System (ADS)

    Minett, A. I.; Fraysse, J.; Gu, G.; Roth, S.

    2001-11-01

    The conversion of electrical energy into mechanical energy using macro scale sheets of carbon nanotubes (bucky paper) has been shown to exhibit comparable or superior performance to that of human skeletal muscle. This level of performance was not as high as predicted by theoretical calculations. Therefore, working from a bottom-up principle, it is of paramount interest to not only demonstrate a single carbon nanotube actuator, but to gain a better understanding of the process of nanotube actuation. In this paper, practical considerations and approaches to the preparation of suspended single walled carbon nanotube (SWNT) structures and the measurement of actuation force are discussed.

  13. A sonochemical route to single-walled carbon nanotubes under ambient conditions.

    PubMed

    Jeong, Soo-Hwan; Ko, Ju-Hye; Park, Jong-Bong; Park, Wanjun

    2004-12-15

    A chemical route to single-walled carbon nanotubes (SWCNTs) under ambient conditions has been developed. Silica powder was immersed in a mixture solution of ferrocene and p-xylene. After sonication at atmospheric pressure and room temperature, we obtained high-purity SWCNTs. Sonochemical effects may lead to producing high-purity SWCNTs. The process could be readily generalized to synthesize other forms of carbon-based materials, such as fullerenes, multiwalled nanotubes, carbon onions, and diamond, in liquid solution under ambient conditions. PMID:15584730

  14. Electron transport properties of a single-walled carbon nanotube in the presence of hydrogen cyanide: first-principles analysis.

    PubMed

    Srivastava, Anurag; Sharma, Vikash; Kaur, Kamalpreet; Khan, Md Shahzad; Ahuja, Rajeev; Rao, V K

    2015-07-01

    First-principles analysis based on density functional theory was performed to compute the electronic and transport properties of a single-walled carbon nanotube in the presence of hydrogen cyanide. A chiral (4,1) carbon nanotube was found to become less metallic as the number of hydrogen cyanide molecules nearby increased. When there were a sufficient number of hydrogen cyanide molecules close to the nanotube, it became semiconducting. This metallic to semiconducting transformation of the nanotube was verified by analyzing its conductance and current as a function of the number of molecules of hydrogen cyanide present. The conductivity of the carbon nanotube was very high when no hydrogen cyanide molecules were present, but decreased considerably when even just a single hydrogen cyanide molecule approached the surface of the nanotube. PMID:26072123

  15. Unique toxicological behavior from single-wall carbon nanotubes separated via selective adsorption on hydrogels.

    PubMed

    Clar, Justin G; Gustitus, Sarah A; Youn, Sejin; Silvera Batista, Carlos A; Ziegler, Kirk J; Bonzongo, Jean Claude J

    2015-03-17

    Over the past decade, extensive research has been completed on the potential threats of single-wall carbon nanotubes (SWCNTs) to living organisms upon release to aquatic systems. However, these studies have focused primarily on the link between adverse biological effects in exposed test organisms on the length, diameter, and metallic impurity content of SWCNTs. In contrast, few studies have focused on the bioeffects of the different SWCNTs in the as-produced mixture, which contain both metallic (m-SWCNT) and semiconducting (s-SWCNT) species. Using selective adsorption onto hydrogels, high purity m-SWCNT and s-SWCNT fractions were produced and their biological impacts determined in dose-response studies with Pseudokirchneriella subcapitata as test organism. The results show significant differences in the biological responses of P. subcapitata exposed to high purity m- and s-SWCNT fractions. Contrary to the biological response observed using SWCNTs separated by density gradient ultracentrifugation, it is found that the high-pressure CO conversion (HiPco) s-SWCNT fraction separated by selective adsorption causes increased biological impact. These findings suggest that s-SWCNTs are the primary factor driving the adverse biological responses observed from P. subcapitata cells exposed to our as-produced suspensions. Finally, the toxicity of the s-SWCNT fraction is mitigated by increasing the concentration of biocompatible surfactant in the suspensions, likely altering the nature of surfactant coverage along SWCNT sidewalls, thereby reducing potential physical interaction with algal cells. These findings highlight the need to couple sample processing and toxicity response studies. PMID:25710331

  16. Control of the Diameter and Chiral Angle Distributions during Production of Single-wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel; Holmes, William; Sosa, Edward; Boul, Peter; Arepalli, Sivaram; Yowell, Leonard

    2008-01-01

    Many applications of single wall carbon nanotubes (SWCNT), especially in microelectronics, will benefit from use of certain (n,m) nanotube types (metallic, small gap semiconductor, etc.). However, as produced SWCNT samples are polydispersed, with many (n,m) types present and typical approximate 1:2 metal/semiconductor ratio. It has been recognized that production of SWCNTs with narrow 'tube type populations' is beneficial for their use in applications, as well as for the subsequent sorting efforts. In the present work, SWCNTs were produced by a pulsed laser vaporization (PLV) technique. The nanotube type populations were studied with respect to the production temperature with two catalyst compositions: Co/Ni and Rh/Pd. The nanotube type populations were measured via photoluminescence, UV-Vis-NIR absorption and Raman spectroscopy. It was found that in the case of Co/Ni catalyst, decreased production temperature leads to smaller average diameter, exceptionally narrow diameter distribution, and strong preference toward (8,7) nanotubes. The other nanotubes present are distributed evenly in the 7-30 deg chiral angle range. In the case of Rh/Pd catalyst, a decrease in the temperature leads to a small decrease in the average diameter, with the chiral angle distribution skewed towards 30 o and a preference toward (7,6), (8,6) and (8,7) nanotubes. However, the diameter distribution remains rather broad. These results demonstrate that PLV production technique can provide at least partial control over the nanotube (n,m) populations. In addition, these results have implications for the understanding the nanotube nucleation mechanism in the laser oven.

  17. Plasma-synthesized single-walled carbon nanotubes and their applications

    NASA Astrophysics Data System (ADS)

    Hatakeyama, R.; Kaneko, T.; Kato, T.; Li, Y. F.

    2011-05-01

    Plasma-based nanotechnology is a rapidly developing area of research ranging from physics of gaseous and liquid plasmas to material science, surface science and nanofabrication. In our case, nanoscopic plasma processing is performed to grow single-walled carbon nanotubes (SWNTs) with controlled chirality distribution and to further develop SWNT-based materials with new functions corresponding to electronic and biomedical applications. Since SWNTs are furnished with hollow inner spaces, it is very interesting to inject various kinds of atoms and molecules into their nanospaces based on plasma nanotechnology. The encapsulation of alkali-metal atoms, halogen atoms, fullerene or azafullerene molecules inside the carbon nanotubes is realized using ionic plasmas of positive and negative ions such as alkali-fullerene, alkali-halogen, and pair or quasipair ion plasmas. Furthermore, an electrolyte solution plasma with DNA negative ions is prepared in order to encapsulate DNA molecules into the nanotubes. It is found that the electronic and optical properties of various encapsulated SWNTs are significantly changed compared with those of pristine ones. As a result, a number of interesting transport phenomena such as air-stable n- and p-type behaviour, p-n junction characteristic, and photoinduced electron transfer are observed. Finally, the creation of an emerging SWNTs-based nanobioelectronics system is challenged. Specifically, the bottom-up electric-field-assisted reactive ion etching is proposed to control the chirality of SWNTs, unexplored SWNT properties of magnetism and superconductivity are aimed at being pioneered, and innovative biomedical-nanoengineering with encapsulated SWNTs of higher-order structure are expected to be developed by applying advanced gas-liquid interfacial plasmas.

  18. Thin single-wall BN-nanotubes formed inside carbon nanotubes

    PubMed Central

    Nakanishi, Ryo; Kitaura, Ryo; Warner, Jamie H.; Yamamoto, Yuta; Arai, Shigeo; Miyata, Yasumitsu; Shinohara, Hisanori

    2013-01-01

    We report a high yield synthesis of single-wall boron nitride nanotubes (SWBNNTs) inside single-wall carbon nanotubes (SWCNTs), a nano-templated reaction, using ammonia borane complexes (ABC) as a precursor. Transmission electron microscope (TEM), high angle annular dark field (HAADF)-scanning TEM (STEM), electron energy loss spectra (EELS) and high resolution EELS mapping using aberration-corrected TEM system clearly show the formation of thin SWBNNTs inside SWCNTs. We have found that the yield of the SWBNNT formation is high and that the most of ABC molecules decompose and fuse to form the thin BNNTs at a temperature of 1,673 K having a narrow diameter distribution of 0.7 ± 0.1 nm. Optical absorption measurements suggest that the band gap of the thin SWBNNTs is about 6.0 eV, which provide the ideal insulator nanotubes with very small diameters. PMID:23459405

  19. Coalescence of parallel finite length single-walled carbon nanotubes by heat treatment

    NASA Astrophysics Data System (ADS)

    Yang, Xueming; Qiao, Fangwei; Zhu, Xiaoxun; Zhang, Pu; Chen, Dongci; To, Albert C.

    2013-03-01

    Fusion of parallel finite length single-walled carbon nanotubes (SWCNTs) without initially introducing structural defects is investigated by molecular dynamics (MD) simulations. Three different models that impose different constraints are adopted to simulate the heat welding and coalescence of the parallel SWCNTs. It is found that the ultrathin as well as some larger diameter, finite length SWCNTs, for example (8,0) and (10,0) SWCNTs can be coalesced to become a unique single-walled tube solely via high temperature heat treatment. It is observed that the ends of the nanotubes are prone to close at high temperature during the high temperature treatment. In addition, the fusion process and mechanism of parallel SWCNTs with different lengths and radii are discussed.

  20. Characterizing energy dissipation in single-walled carbon nanotube polycarbonate composites

    NASA Astrophysics Data System (ADS)

    Koratkar, Nikhil A.; Suhr, Jonghwan; Joshi, Amit; Kane, Ravi S.; Schadler, Linda S.; Ajayan, Pulickel M.; Bartolucci, Steve

    2005-08-01

    In this study, single-walled carbon nanotube and bisphenol-A-polycarbonate composite beams were fabricated by a solution mixing process and dynamic (cyclic) load tests were performed to characterize energy dissipation. We report up to an order of magnitude (>1000%) increase in loss modulus of the polycarbonate system with the addition of 2% weight fraction of oxidized single-walled nanotube fillers. We show that the increase in damping is derived from frictional sliding at the nanotube-polymer interfaces. The nanoscale dimensions of the tubes not only result in large interfacial contact area, thereby generating high damping efficiency, but also enable seamless integration of the filler materials into the composite structure.

  1. Simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma.

    PubMed

    Li, Jian; Shashurin, Alexey; Kundrapu, Madhusudhan; Keidar, Michael

    2012-01-01

    Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices(1-4). Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT (5), narrow the diameter distribution of metallic catalyst particles and carbon nanotubes (6), and change the ratio of metallic and semiconducting carbon nanotubes (7), as well as lead to graphene synthesis (8). Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the

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

    PubMed

    Hou, Wen-Che; He, Chen-Jing; Wang, Yi-Sheng; Wang, David K; Zepp, Richard G

    2016-04-01

    Single-walled carbon nanotubes (SWCNTs) with proper functionalization are desirable for applications that require dispersion in aqueous and biological environments, and functionalized SWCNTs also serve as building blocks for conjugation with specific molecules in these applications. In this study, we examined the phototransformation of carboxylated SWCNTs and associated amorphous carbon impurities in the presence or absence of H2O2 under simulated sunlight conditions. We found that while carboxylated SWCNTs were rather unreactive with respect to direct solar photolysis, they photoreacted in the presence of H2O2, forming CO2 and strongly aggregated SWCNT products that precipitated. Photoreaction caused SWCNTs to lose oxygen-containing functionalities, and interestingly, the resulting photoproducts had spectral characteristics similar to those of parent carboxylated SWCNTs whose amorphous carbon was removed by base washing. These results indicated that photoreaction of the amorphous carbon was likely involved. The removal of amorphous carbon after indirect photoreaction was confirmed with thermogravimetric analysis (TGA). Further studies using carboxylated SWCNTs with and without base washing indicate that amorphous carbon reduced the extent of aggregation caused by photoreaction. The second-order rate constant for carboxylated SWCNTs reacting with (•)OH was estimated to be in the range of 1.7-3.8 × 10(9) MC(-1) s(-1). The modeled phototransformation half-lives fall in the range of 2.8-280 days in typical sunlit freshwaters. Our study indicates that photosensitized reactions involving (•)OH may be a transformation and removal pathway of functionalized SWCNTs in the aquatic environment, and that the residual amorphous carbon associated with SWCNTs plays a role in SWCNT stabilization. PMID:26928260

  3. Ion transport and electrochemical tuning of Fermi level in single-wall carbon nanotube probed by in situ Raman scattering

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Robertson, J.

    2006-10-01

    In situ Raman spectroscopy technique was employed to investigate the ion transport process and to determine the concomitant electrochemical tuning of Fermi level in single-wall carbon nanotube. The variation of structural bonding in single-wall carbon nanotube bundle dipped in aqueous alkaline earth halide electrolyte such as CaCl2 with electrochemical biasing was monitored. It is because Raman can detect changes in C-C bond length through radial breathing mode at ˜184cm-1 that varies inversely with the nanotube diameter and the G band at ˜1590cm-1 that varies with the axial bond length. Consistent reversible and substantial variations in Raman intensity of both the modes induced by electrode potential point at the fine and continuous tuning (alternatively, emptying/depleting or filling) of the specific bonding and antibonding states. Qualitatively, the results were explained in terms of changes in the energy gaps between the one-dimensional van Hove singularities present in the electron density of states arising possibly due to the alterations in the overlap integral of π bonds between the p orbitals of the adjacent carbon atoms. We estimated the extent of variation of the absolute potential of the Fermi level and overlap integral (γ0) between the nearest-neighbor carbon atoms from modeling the electrochemical potential dependence of Raman intensity. Observations also suggest that the work function of the tube is larger for the metallic nanotubes in contrast to the simultaneously present semiconducting nanotubes.

  4. Carbohydrate Conjugation through Microwave-Assisted Functionalization of Single-Walled Carbon Nanotubes Using Perfluorophenyl Azides

    PubMed Central

    Kong, Na; Shimpi, Manishkumar R.; Park, Jae Hyeung

    2015-01-01

    Carbohydrate-functionalized single-walled carbon nanotubes (SWNTs) were synthesized using microwave-assisted reaction of perfluorophenyl azide with the nanotubes. The results showed that microwave radiation provides a rapid and effective means to covalently attach carbohydrates to SWNTs, producing carbohydrate-SWNT conjugates for biorecognition. The carbohydrate-functionalized SWNTs were furthermore shown to interact specifically with cognate carbohydrate-specific proteins (lectins), resulting in predicted recognition patterns. The carbohydrate-presenting SWNTs constitute a new platform for sensitive protein- or cell recognition, which pave the way for glycoconjugated carbon nanomaterials in biorecognition applications. PMID:25746392

  5. Determination of the acidic sites of purified single-walled carbon nanotubes by acid base titration

    NASA Astrophysics Data System (ADS)

    Hu, H.; Bhowmik, P.; Zhao, B.; Hamon, M. A.; Itkis, M. E.; Haddon, R. C.

    2001-09-01

    We report the measurement of the acidic sites in three different samples of commercially available full-length purified single-walled carbon nanotubes (SWNTs) - as obtained from CarboLex (CLI), Carbon Solutions (CSI) and Tubes@Rice (TAR) - by simple acid-base titration methods. Titration of the purified SWNTs with NaOH and NaHCO 3 solutions was used to determine the total percentage of acidic sites and carboxylic acid groups, respectively. The total percentage of acidic sites in full length purified SWNTs from TAR, CLI and CSI are about 1-3%.

  6. A comparative study of argon ion irradiated pristine and fluorinated single-wall carbon nanotubes

    SciTech Connect

    Fedoseeva, Yu. V.; Bulusheva, L. G.; Okotrub, A. V.; Vyalikh, D. V.; Fonseca, A.

    2010-12-14

    Effect of Ar{sup +} ion irradiation on the structure of pristine and fluorinated single-wall carbon nanotubes (SWCNTs) was examined using transmission electron microscopy (TEM), Raman, and x-ray photoelectron spectroscopy (XPS). The TEM analysis revealed retention of tubular structures in both irradiated samples while Raman spectroscopy and XPS data indicated a partial destruction of nanotubes and formation of oxygen-containing groups on the nanotube surface. From similarity of electronic states of carbon in the irradiated pristine and fluorinated SWCNTs observed by XPS, it was suggested that defluorination of nanotubes proceeded with breaking of C-F bonds.

  7. High structural stability of single wall carbon nanotube under quasi-hydrostatic high pressures

    NASA Astrophysics Data System (ADS)

    Chen, Jing-Yin; Kim, Minseob; Yoo, Choong-Shik

    2009-09-01

    In quasi-hydrostatic conditions, single wall carbon nanotubes (SWNTs) exhibit high structural stability to ˜35 GPa, well beyond the stability of sp2 C dbnd C bonds in graphite, carbon fullerenes, benzene, and other hydrocarbons. The pressure-induced Raman changes of SWNT are completely reversible below 16 GPa, partially reversible between 16 and 35 GPa, and irreversible beyond 35 GPa where it turns into highly disordered graphite. We explain the high stability in terms of the pressure-induced structural modification to an interlinked configuration, which occurs reversibly under substantial sp3 hybridization (˜20%) and, thus, increases the stability of sp2 C dbnd C bonds in the SWNTs.

  8. Ferromagnetic properties of single-walled carbon nanotubes synthesized by Fe catalyst arc discharge

    NASA Astrophysics Data System (ADS)

    Ha, Byeongchul; Yeom, Tae Ho; Lee, Soo Hyung

    2009-05-01

    Single-walled carbon nanotubes (SWCNTs) were directly synthesized by a hydrogen arc discharge method using only Fe catalyst. The synthesized carbon materials indicated high-purity SWCNTs with Fe catalyst encapsulated with several graphite layers. The diameter of Fe catalysts encapsulated with graphene layers is 1.5-2.0 nm. From the ferromagnetic resonance measurements, the as-synthesized SWCNTs show the ferromagnetic properties at room temperature. The ferromagnetic properties of SWCNTs would be attributed to Fe catalysts encapsulated by graphite layers.

  9. Dependence of Thermal Conductivity on Thickness in Single-Walled Carbon Nanotube Films.

    PubMed

    Lee, Kyung-Min; Shrestha, Ramesh; Dangol, Ashesh; Chang, Won Seok; Coker, Zachary; Choi, Tae-Youl

    2016-01-01

    Herein, we report experimentally dependence of thermal conductivity on thickness of single walled carbon nanotubes (SWNTs) thin films; the measurements are based on the micropipette thermal sensor technique. Accurate and well resolved measurements of thermal conductivity made by the micropipette sensor showed a correlated behavior of thickness and thermal conductivity of CNT films that thermal conductivity decreased as thickness increased. The thickness dependence is explained by reduction of mean free path (MFP), which is induced by more intertubular junctions in more dense-packed carbon nanotube (CNT) networks; the thicker SWCNT films were revealed to have higher density. PMID:27398564

  10. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors arrays

    SciTech Connect

    Seo, M.; Kim, H.; Kim, Y. H.; Yun, H.; McAllister, K.; Lee, S. W.; Na, J.; Kim, G. T.; Lee, B. J.; Kim, J. J.; Jeong, G. H.; Lee, I.; Kim, K. S.

    2015-07-20

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode patterns on top of the aligned SWNT along one direction. Both single and multi layer graphene were used for the electrode materials; typical p-type transistor and Schottky diode behavior were observed, respectively. Based on our fabrication method and device performances, several issues are suggested and discussed to improve the device reliability and finally to realize all carbon based future electronic systems.

  11. Effective permittivity of single-walled carbon nanotube composites: Two-fluid model

    SciTech Connect

    Moradi, Afshin; Zangeneh, Hamid Reza; Moghadam, Firoozeh Karimi

    2015-12-15

    We develop an effective medium theory to obtain effective permittivity of a composite of two-dimensional (2D) aligned single-walled carbon nanotubes. Electronic excitations on each nanotube surface are modeled by an infinitesimally thin layer of a 2D electron gas represented by two interacting fluids, which takes into account different nature of the σ and π electrons. Calculations of both real and imaginary parts of the effective dielectric function of the system are presented, for different values of the filling factor and radius of carbon nanotubes.

  12. Advances in NO2 sensing with individual single-walled carbon nanotube transistors

    PubMed Central

    Muoth, Matthias; Roman, Cosmin; Haluska, Miroslav; Hierold, Christofer

    2014-01-01

    Summary The charge carrier transport in carbon nanotubes is highly sensitive to certain molecules attached to their surface. This property has generated interest for their application in sensing gases, chemicals and biomolecules. With over a decade of research, a clearer picture of the interactions between the carbon nanotube and its surroundings has been achieved. In this review, we intend to summarize the current knowledge on this topic, focusing not only on the effect of adsorbates but also the effect of dielectric charge traps on the electrical transport in single-walled carbon nanotube transistors that are to be used in sensing applications. Recently, contact-passivated, open-channel individual single-walled carbon nanotube field-effect transistors have been shown to be operational at room temperature with ultra-low power consumption. Sensor recovery within minutes through UV illumination or self-heating has been shown. Improvements in fabrication processes aimed at reducing the impact of charge traps have reduced the hysteresis, drift and low-frequency noise in carbon nanotube transistors. While open challenges such as large-scale fabrication, selectivity tuning and noise reduction still remain, these results demonstrate considerable progress in transforming the promise of carbon nanotube properties into functional ultra-low power, highly sensitive gas sensors. PMID:25551046

  13. Electrical properties of gas sensors based on graphene and single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kondrashov, Ivan I.; Sokolov, Igor V.; Rusakov, Pavel S.; Rybin, Maxim G.; Barmin, Alexander A.; Rizakhanov, Razhudin N.; Obraztsova, Elena D.

    2016-01-01

    Here, we present investigation of the influence of different gases (carbon dioxide, ammonia, and iodine vapor) on the sensory properties of graphene and single-wall carbon nanotube films. The gas molecules are adsorbed by carbon films (graphene or nanotubes) and change the film's electrical resistance. In the course of this work, the setup for studying the electrophysical properties of carbon nanomaterials has been designed and constructed in the lab. With this home-made equipment, we have demonstrated a high efficiency of graphene and nanotubes as adsorbents of different gases and a possibility to use these materials as gas sensors. We have also performed a chemical modification of graphene and carbon nanotubes by attaching the nanoparticles of calcium carbonate (CaCO3) to improve the sensitivity and selectivity of sensors.

  14. Advanced Characterization and Optical Properties of Single-Walled Carbon Nanotubes and Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Naumov, Anton Viatcheslavovich

    Photophysical, electronic, and compositional properties of single-walled carbon nanotubes (SWCNTs) and bulk nanotube samples were investigated together with graphene oxide photoluminescence. First, we studied the effect of external electric fields on SWCNT photoluminescence. Fields of up to 107 V/m caused dramatic, reversible decreases in emission intensity. Quenching efficiency was proportional to the projection of the field on the SWCNT axis, and showed inverse correlation with optical band gap. The magnitude of the effect was experimentally related to exciton binding energy, as consistent with a proposed field-induced exciton dissociation model. Further, the electronic composition of various SWCNT samples was studied. A new method was developed to measure the fraction of semiconducting nanotubes in as- grown or processed samples. SWCNT number densities were compared in images from near-IR photoluminescence (semiconducting species) and AFM (all species) to compute the semiconducting fraction. The results provide important information about SWCNT sample compositions that can guide controlled growth methods and help calibrate bulk characterization techniques. The nature of absorption backgrounds in SWCNT samples was also studied. A number of extrinsic perturbations such as extensive ultrasonication, sidewall functionalization, amorphous carbon impurities, and SWCNT aggregation were applied and their background contributions quantified. Spectral congestion backgrounds from overlapping absorption bands were assessed with spectral modeling. Unlike semiconducting nanotubes, metallic SWCNTs gave broad intrinsic absorption backgrounds. The shape of the metallic background component and its absorptivity coefficient were determined. These results can be used to minimize and evaluate SWCNT absorption backgrounds. Length dependence of SWCNT optical properties was investigated. Samples were dispersed by ultrasonication or shear processing, and then length-fractionated by gel

  15. G-band resonant Raman study of 62 isolated single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jorio, A.; Souza Filho, A. G.; Dresselhaus, G.; Dresselhaus, M. S.; Swan, A. K.; Ünlü, M. S.; Goldberg, B. B.; Pimenta, M. A.; Hafner, J. H.; Lieber, C. M.; Saito, R.

    2002-04-01

    We report G-band resonance Raman spectra of single-wall carbon nanotubes (SWNTs) at the single-nanotube level. By measuring 62 different isolated SWNTs resonant with the incident laser, and having diameters dt ranging between 0.95 nm and 2.62 nm, we have conclusively determined the dependence of the two most intense G-band features on the nanotube structure. The higher-frequency peak is not diameter dependent (ω+G=1591 cm-1), while the lower-frequency peak is given by ω-G=ω+G-C/d2t, with C being different for metallic and semiconducting SWNTs (CM>CS). The peak frequencies do not depend on nanotube chiral angle. The intensity ratio between the two most intense features is in the range 0.1

  16. Carbon nanotunnels form from single-walled carbon nanotubes interacting with a diamond (100)-(2 X 1) surface.

    SciTech Connect

    Horner, D. A.; Sternberg, M.; Zapol, P.; Curtiss, L. A.

    2011-08-01

    A quantum chemical study of the interaction of (5,5), (7,7), (9,9) and (8,0) single-walled carbon nanotubes with a clean (100)-(2 x 1) diamond surface is reported. Stable structures with covalent bonds at the interface were found for carbon nanotubes oriented parallel or perpendicular to the dimer rows on the reconstructed (100) surface. The binding energy of the most stable (5,5) nanotube-diamond structure is 1.7 eV/{angstrom}, and is attributed to strong covalent bonds formed between the carbon nanotube and the diamond surface. The structure of the nanotube is distorted by adsorption on the surface such that it adopts a tunnel-like geometry. Two other nanotunnel geometries were found for the (5,5) nanotube, with binding energies of 1.39 and 1.09 eV/{angstrom}. In the most stable (5,5) nanotube-diamond structure the interaction between the nanotube and the diamond surface produces a 0.6 eV band gap near the Fermi level, but the metallic character of the nanotube is maintained in the two other, less strongly bound nanotunnel structures. No charge transfer occurs between the diamond surface and the nanotunnels in any of the three orientations. Binding energies decrease with increases in tube diameter, to the extent that one of the three nanotunnel structures is not formed by (9,9) carbon nanotubes.

  17. Single-walled carbon nanotubes acquire a specific lectin-affinity through supramolecular wrapping with lactose-appended schizophyllan.

    PubMed

    Hasegawa, Teruaki; Fujisawa, Tomohisa; Numata, Munenori; Umeda, Mariko; Matsumoto, Takahiro; Kimura, Taro; Okumura, Shiro; Sakurai, Kazuo; Shinkai, Seiji

    2004-10-01

    Single-walled carbon nanotubes can be entrapped within a helical superstructure composed of schizophyllan bearing lactoside-appendages to show an excellent water-solubility as well as a specific lectin-affinity. PMID:15467846

  18. Photoinduced Spontaneous Free-Carrier Generation in Semiconducting Single-Walled Carbon Nanotubes

    SciTech Connect

    Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.; Rumbles, Garry

    2015-11-04

    The strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. We found that the conditions of the microwave conductivity measurement allow us to avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. At low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions.

  19. Photoinduced spontaneous free-carrier generation in semiconducting single-walled carbon nanotubes

    PubMed Central

    Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.; Rumbles, Garry

    2015-01-01

    Strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. The conditions of the microwave conductivity measurement allow us to avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. Even at low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions. PMID:26531728

  20. Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm

    PubMed Central

    Asghar, Waseem; Shafiee, Hadi; Velasco, Vanessa; Sah, Vasu R.; Guo, Shirui; El Assal, Rami; Inci, Fatih; Rajagopalan, Adhithi; Jahangir, Muntasir; Anchan, Raymond M.; Mutter, George L.; Ozkan, Mihrimah; Ozkan, Cengiz S.; Demirci, Utkan

    2016-01-01

    Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1–25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure. PMID:27538480

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

    NASA Astrophysics Data System (ADS)

    Günay, E.

    2016-04-01

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

  2. Photoinduced Spontaneous Free-Carrier Generation in Semiconducting Single-Walled Carbon Nanotubes

    DOE PAGESBeta

    Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.; Rumbles, Garry

    2015-11-04

    The strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. We found that the conditions of the microwave conductivity measurement allow us tomore » avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. At low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions.« less

  3. Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm.

    PubMed

    Asghar, Waseem; Shafiee, Hadi; Velasco, Vanessa; Sah, Vasu R; Guo, Shirui; El Assal, Rami; Inci, Fatih; Rajagopalan, Adhithi; Jahangir, Muntasir; Anchan, Raymond M; Mutter, George L; Ozkan, Mihrimah; Ozkan, Cengiz S; Demirci, Utkan

    2016-01-01

    Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1-25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure. PMID:27538480

  4. Organic/hybrid nanoparticles and single-walled carbon nanotubes: preparation methods and chiral applications.

    PubMed

    Alhassen, Haysem; Antony, Vijy; Ghanem, Ashraf; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Ostrikov, Kostya Ken

    2014-11-01

    Nanoparticles are molecular-sized solids with at least one dimension measuring between 1-100 nm or 10-1000 nm depending on the individual discipline's perspective. They are aggregates of anywhere from a few hundreds to tens of thousands of atoms which render them larger than molecules but smaller than bulk solids. Consequently, they frequently exhibit physical and chemical properties somewhere between. On the other hand, nanocrystals are a special class of nanoparticles which have started gaining attention recently owing to their unique crystalline structures which provide a larger surface area and promising applications including chiral separations. Hybrid nanoparticles are supported by the growing interest of chemists, physicists, and biologists, who are researching to fully exploit them. These materials can be defined as molecular or nano-composites with mixed (organic or bio) and inorganic components, where at least one of the component domain has a dimension ranging from a few Å to several nanometers. Similarly, and due to their extraordinary physical, chemical, and electrical properties, single-walled carbon nanotubes have been the subject of intense research. In this short review, the focus is mainly on the current well-established simple preparation techniques of chiral organic and hybrid nanoparticles as well as single-walled carbon nanotubes and their applications in separation science. Of particular interest, cinchonidine, chitosan, and β-CD-modified gold nanoparticles (GNPs) are discussed as model examples for organic and hybrid nanoparticles. Likewise, the chemical vapor deposition method, used in the preparation of single-walled carbon nanotubes, is discussed. The enantioseparation applications of these model nanomaterials is also presented. PMID:24811353

  5. Vertical devices from single-walled carbon nanotubes templated in porous anodic alumina

    NASA Astrophysics Data System (ADS)

    Franklin, Aaron D.

    Over the past decade, tremendous progress has been realized in the fabrication and characterization of single-walled carbon nanotube (CNT) electronic devices. For example, with advantages such as ballistic transport and the absence of surface states, CNTs have been proposed as an ideal 1D channel material for next generation field-effect transistors (FETs). However, the literature is replete with reports of individual high-performance devices that lack the demonstration or feasibility of being fabricated at a large scale. One of the primary obstacles to fabricating highly integrated CNT devices is the placement of the nanotubes at a defined spacing and in precise locations. Nearly all CNT devices to date have been configured in a planar geometry (with the CNT supported horizontally on a substrate) and have primarily relied on random processes for dispersing/growing and contacting the CNTs. Ideally, a high-performance CNTFET would consist of multiple, densely packed CNTs that are aligned, having surround gates, low-barrier contacts, and a sub-100 nm channel length. Such multi-nanotube CNTFETs should further be fabricated in a manner that can be scaled for high-level integration and that is compatible with modern CMOS processing. This dissertation describes the development of a platform based on vertically aligned CNTs templated in porous anodic alumina (PAA) for the scalable fabrication of multi-nanotube CNTFETs with surround gates as well as several other nanoelectronic devices. PAA is a template consisting of hexagonally ordered pores that result from the anodization of an Al film. By embedding a catalyst layer within PAA, single-walled CNTs are synthesized from the nanoscale vertical pores (pore diameter ≈20 nm, spacing ≈100 nm) at a yield of no more than one nanotube per pore. After synthesis, the CNTs are contacted within the pores by electrodepositing Pd, a known low-barrier contact metal for CNTs, to form nanowires that electrically address the CNTs near

  6. Human Airway Epithelial Cell Responses to Single Walled Carbon Nanotube Exposure: Nanorope-Residual Body Formation

    SciTech Connect

    Panessa-Warren, Barbara J.; Warren, John B.; Kisslinger, Kim; Crosson, Kenya; Maye, Mathew M.

    2012-11-01

    This investigation examines the 'first contact responses' of in vitro human epithelial airway cells exposed to unrefined single walled carbon nanotubes (SWCNTs) [containing metal catalyst, carbon black, amorphous carbon, graphitic shells, and SWCNTs], and refined acid/peroxide cleaned and cut SWCNTs at low and high dose exposures (0.16 ug/L and 1.60 ug/L) for 2, 3 and 3.5 hours. FTIR, X-ray compositional analysis, morphological TEM analysis and UV-Vis were used to physicochemically characterize the SWCNTs in this study. Following SWCNT exposure to human lung NCI-H292 epithelial monolayers, the airway cells were prepared for light microscopy vital staining, or fixed in glutaraldehyde for SEM/TEM imaging to determine SWCNT binding, uptake, intracellular processing and organellar/SWCNT fate within the exposure period. At 2 hr exposures to both unrefined Carbolex, and refined SWCNTs (at both high and low doses), there were no increases in lung cell necrosis compared to controls. However high dose, 3 hr exposures to unrefined Carbolex material produced severe cell damage (apical and basal plasma membrane holes, decreased mitochondria, numerous intracellular vesicles containing nanomaterial and membrane fragments) and increased cell necrosis. The refined SWCNTs exposed for 3 hr at low dose produced no increase in cell death, although high dose exposure produced significant cell death. By TEM, Acid/peroxide cleaned SWCNT 3 hr exposures at high and low doses, revealed SWCNTs attachment to cell surface mucin, and SWCNT uptake into the cells during membrane recycling. Membranes and SWCNTs were seen within cytoplasmic lamellar body-type vesicles, where vesicular contents were bio-degraded, eventually forming long SWCNT-nanoropes, which were subsequently released into the cytoplasm as clusters of attached nanoropes, as the vesicle membranes fragmented. These Nanorope-Residual Bodies did not cause damage to the surrounding organelles or cytoplasm, and seemed very stabile in the

  7. Fabrication of Dense Horizontally Aligned Arrays of Single-Wall Carbon Nanotubes from Vertically Aligned Arrays

    NASA Astrophysics Data System (ADS)

    Zheng, Gang; Wang, Xueshen; Li, Qunqing; Xie, Jing; Zhu, Zhendong; Zou, Yuan; Liu, Junku; Jiang, Kaili; Fan, Shoushan

    2011-01-01

    The as-grown vertically aligned single-wall carbon nanotube (SWNT) arrays are transferred from the original silicon substrate to a poly(ethylene terephthalate) (PET) substrate, which acts as a stamp. Thin SWNT films can be applied from the stamp to the target substrate and subsequently treated by an ultrasonic process to reduce their thickness to 6.6 nm. The transferred SWNT thin film retains the advantageous super-alignment and high-density properties of the vertical SWNT arrays. The linear density, transmittance, and square resistance of the thin film are as high as 15 tubes per micrometer, 99% at 550 nm, and 16 kΩ, respectively.

  8. Temperature Dependence of the Thermal Conductivity of Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Osman, Mohamed A.; Srivastava, Deepak

    2000-01-01

    The thermal conductivity of several single wall carbon nanotubes (CNT) has been calculated over a temperature range of 100-500 K using molecular dynamics simulations with Tersoff-Brenner potential for C-C interactions. In all cases, starting from similar values at 100K, thermal conductivities show a peaking behavior before falling off at higher temperatures. The peak position shifts to higher temperatures for nanotubes of larger diameter, and no significant dependence on the tube chirality is observed. It is shown that this phenomenon is due to onset of Umklapp scattering, which shifts to higher temperatures for nanotubes of larger diameter.

  9. Influence of cysteine doping on photoluminescence intensity from semiconducting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kurnosov, N. V.; Leontiev, V. S.; Linnik, A. S.; Karachevtsev, V. A.

    2015-03-01

    Photoluminescence (PL) from semiconducting single-walled carbon nanotubes can be applied for detection of cysteine. It is shown that cysteine doping (from 10-8 to 10-3 M) into aqueous suspension of nanotubes with adsorbed DNA leads to increase of PL intensity. The PL intensity was enhanced by 27% at 10-3 M cysteine concentration in suspension. Most likely, the PL intensity increases due to the passivation of p-defects on the nanotube by the cysteine containing reactive thiol group. The effect of doping with other amino acids without this group (methionine, serine, aspartic acid, lysine, proline) on the PL intensity is essentially weaker.

  10. Fatigue failure mechanisms of single-walled carbon nanotube ropes embedded in epoxy

    NASA Astrophysics Data System (ADS)

    Ren, Y.; Fu, Y. Q.; Liao, K.; Li, F.; Cheng, H. M.

    2004-04-01

    In this work, fatigue failure mechanisms of single-walled carbon nanotube (SWCNT) bundles embedded in epoxy matrix under repeated tensile load were studied. Observed damage and failure modes include: (1) splitting of SWCNT bundles, (2) kink formation and subsequent failure in SWCNTs, and (3) fracture of SWCNT bundles. Patterns of crack propagation under tension in SWCNTs were studied by molecular mechanics simulations, where defect-free SWCNTs and SWCNTs with two different modes of Stone-Wales defects were studied. It is demonstrated by the results of molecular mechanics simulation that the observed fracture surfaces of SWCNT can be reproduced reasonably well, suggesting possible fatigue failure mechanisms of SWCNT in the composite.

  11. Reinforcement of semicrystalline polymers with collagen-modified single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Sanjib; Salvetat, Jean-Paul; Saboungi, Marie-Louise

    2006-06-01

    We report on the enhancement of the mechanical properties of single wall carbon nanotube (SWNT)-polyvinyl alcohol (PVA) composites through functionalization of SWNTs with denatured collagen. In addition to improving compatibility with the matrix, the denatured collagen layer was found to increase the PVA matrix crystallinity, which results in a dramatic enhancement of the Young's modulus (260%), tensile strength (300%), and toughness (700%) well above what can be expected with the classical rule of mixture. A supramolecular organization at the interface is associated with an increase of PVA crystallinity as shown by the x-ray diffraction and differential scanning calorimetry.

  12. Polarized resonance Raman spectroscopy of single-wall carbon nanotubes within a polymer under strain

    NASA Astrophysics Data System (ADS)

    Frogley, M. D.; Zhao, Q.; Wagner, H. D.

    2002-03-01

    The D* Raman band of single-wall carbon nanotubes aligned by shear flow in a polymer matrix has been measured as a function of tensile strain. The Raman intensity varies with the optical polarization direction, an effect which is used here to assess the degree of tube alignment. The strain dependence of the Raman shift depends strongly on the nanotube orientation and the polarization direction. We show that, using polarized light, unoriented nanotubes can be used as strain sensors so that no tube alignment is necessary and the strain can be measured in all directions in a single sample.

  13. [Surface modification and microstructure of single-walled carbon nanotubes for dental composite resin].

    PubMed

    Xia, Yang; Zhang, Feimin; Xu, Li'na; Gu, Ning

    2006-12-01

    In order to improve its dispersion condition in dental composite resin and enhance its interaction with the matrix, single-walled carbon nanotubes(SWNTs) were refluxed and oxidized, then treated by APTE. Their outer surface were coated by nano-SiO2 particles using sol-gel process, then further treated by organosilanes ATES. IR and TEM were used to analyze modification results. TEM pictures showed nano-particles were on the surface of SWNTs; IR showed characteristic adsorbing bands of SiO2. Composite resin specimen with modified SWNTs was prepared and examined by TEM. SWNTs were detected in composite resin matrix among other inorganic fillers. PMID:17228726

  14. Quantification of thin graphene sheets contained in spherical aggregates of single-walled carbon nanohorns

    NASA Astrophysics Data System (ADS)

    Irie, Michiko; Nakamura, Maki; Zhang, Minfang; Yuge, Ryota; Iijima, Sumio; Yudasaka, Masako

    2010-11-01

    Spherical aggregates of single-walled carbon nanohorns (SWNHs) produced by CO 2 laser ablation of graphite contain thin graphene sheets (TGSs), and their quantities depend on formation conditions. To adjust laser ablation condition to increase TGS quantities, TGS quantification in products is necessary; however, its method has not been established. We have found that high resolution thermogravimetric analysis (HRTGA) showed SWNHs and TGSs combusting at 554 and 581 °C, respectively. Transmission electron microscopy observations of HRTGA-residues obtained by stopping HRTGA on the way supported these assignments. Thus TGS was able to be quantified by analyzing derivative curves of weight vs. temperature curves.

  15. Creep-resistant composites of alumina and single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zapata-Solvas, Eugenio; Poyato, Rosalía; Gómez-García, Diego; Domínguez-Rodríguez, Arturo; Radmilovic, Velimir; Padture, Nitin P.

    2008-03-01

    Composites of alumina (Al2O3) ceramic and single-wall carbon nanotubes (SWNTs) have been tested in uniaxial compression at 1300 and 1350°C (Ar atmosphere), and they have been found to be about two orders of magnitude more creep-resistant compared to a pure alumina of about the same grain size (0.5μm). This is attributed to partial blocking of grain-boundary sliding by SWNTs in the composites. Since the grain boundaries in the ceramic/SWNTs composites are amenable to being engineered, this constitutes an attractive approach to the design of creep-resistant ceramic composites.

  16. Effects of ion beam heating on Raman spectra of single-walled carbon nanotubes

    SciTech Connect

    Hulman, Martin; Skakalova, Viera; Krasheninnikov, A. V.; Roth, S.

    2009-02-16

    Free standing films of single-wall carbon nanotubes were irradiated with energetic N{sup +} and C{sup 4+} ions. The observed changes in the Raman line shape of the radial breathing mode and the G band of the C{sup 4+} irradiated samples were similar to those found for a thermally annealed sample. We ascribe these changes to thermal desorption of volatile dopants from the initially doped nanotubes. A simple geometry of the experiment allows us to estimate the temperature rise by one-dimensional heat conductance equation. The calculation indicates that irradiation-mediated increase in temperature may account for the observed Raman spectra changes.

  17. Hydrogenation of single-wall carbon nanotubes using polyamine reagents: combined experimental and theoretical study.

    PubMed

    Miller, Glen P; Kintigh, Jeremy; Kim, Eunja; Weck, Philippe F; Berber, Savas; Tomanek, David

    2008-02-20

    We combine experimental observations with ab initio calculations to study the reversible hydrogenation of single-wall carbon nanotubes using high boiling polyamines as hydrogenation reagents. Our calculations characterize the nature of the adsorption bond and identify preferential adsorption geometries at different coverages. We find the barrier for sigmatropic rearrangement of chemisorbed hydrogen atoms to be approximately 1 eV, thus facilitating surface diffusion and formation of energetically favored, axially aligned adsorbate chains. Chemisorbed hydrogen modifies the structure and stability of nanotubes significantly and increases the inter-tube distance, thus explaining the improved dispersability in solvents like methanol, ethanol, chloroform, and benzene. PMID:18220395

  18. Universal empirical formula for optical transition energies of semiconducting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jamal, G. R. Ahmed; Mominuzzaman, S. M.

    2016-01-01

    A general empirical relation for calculating first seven optical transition energies of semiconducting single wall carbon nanotubes (SWCNTs) is proposed here for the first time. The proposed formula effectively relates first seven optical transition energies of semiconducting SWCNTs with their chiral indices (n, m) through exponential form containing two specific terms (n+2m) and (2n-m). Both mod 1 and mod 2 types of semiconducting tubes are considered here over a wide diameter range from 0.4 nm to 4.75 nm. It was observed that the proposed empirical relations can predict the recent experimental data of those optical transitions with high accuracy.

  19. All-optical trion generation in single-walled carbon nanotubes.

    PubMed

    Santos, Silvia M; Yuma, Bertrand; Berciaud, Stéphane; Shaver, Jonah; Gallart, Mathieu; Gilliot, Pierre; Cognet, Laurent; Lounis, Brahim

    2011-10-28

    We present evidence of all-optical trion generation and emission in pristine single-walled carbon nanotubes (SWCNTs). Luminescence spectra, recorded on individual SWCNTs over a large cw excitation intensity range, show trion emission peaks redshifted with respect to the bright exciton peak. Clear chirality dependence is observed for 22 separate SWCNT species, allowing for determination of electron-hole exchange interaction and trion binding energy contributions. Luminescence data together with ultrafast pump-probe experiments on chirality-sorted bulk samples suggest that exciton-exciton annihilation processes generate dissociated carriers that allow for trion creation upon a subsequent photon absorption event. PMID:22107671

  20. Nonlinear photoluminescence properties of trions in hole-doped single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Akizuki, Naoto; Iwamura, Munechiyo; Mouri, Shinichiro; Miyauchi, Yuhei; Kawasaki, Tomohiro; Watanabe, Hiroshi; Suemoto, Tohru; Watanabe, Kouta; Asano, Kenichi; Matsuda, Kazunari

    2014-05-01

    We studied the excitation density dependence of photoluminescence (PL) spectra of excitons and trions (charged excitons) in hole-doped single-walled carbon nanotubes. We found that the PL intensity of trions exhibited a strong nonlinear saturation behavior as the excitation density increased, whereas that of excitons exhibited a weak sublinear behavior. The strong PL saturation of trions is attributed to depletion of doped holes that are captured by excitons in the formation processes. Moreover, the effective radiative lifetime of a trion was evaluated to be approximately 20 ns.

  1. On the charge transfer between single-walled carbon nanotubes and graphene

    SciTech Connect

    Rao, Rahul Pierce, Neal; Dasgupta, Archi

    2014-08-18

    It is important to understand the electronic interaction between single-walled carbon nanotubes (SWNTs) and graphene in order to use them efficiently in multifunctional hybrid devices. Here, we deposited SWNT bundles on graphene-covered copper and SiO{sub 2} substrates by chemical vapor deposition and investigated the charge transfer between them by Raman spectroscopy. Our results revealed that, on both copper and SiO{sub 2} substrates, graphene donates electrons to the SWNTs, resulting in p-type doped graphene and n-type doped SWNTs.

  2. Single wall carbon nanohorn as a drug carrier for controlled release

    NASA Astrophysics Data System (ADS)

    Xu, Jianxun; Yudasaka, Masako; Kouraba, Sachio; Sekido, Mitsuru; Yamamoto, Yuhei; Iijima, Sumio

    2008-08-01

    A single wall carbon nanohorn (SWNH) is a new kind of single-graphene tubules with a diameter of 2-5 nm and a length 40-50 nm. In this work, we used oxidized SWNH (SWNHox) to incorporate vancomycin hydrochloride (VCM) for its controlled release by taking advantage of the interactions between VCM and SWNHox. Phospholipid-poly(ethylene glycol) was used to modify the hydrophobic surface of SWNHox to improve its dispersion in aqueous systems. In the release study using this complex, a stable release of VCM was achieved for an extended period.

  3. Robust cyclohexanone selective chemiresistors based on single-walled carbon nanotubes.

    PubMed

    Frazier, Kelvin M; Swager, Timothy M

    2013-08-01

    Functionalized single-walled carbon nanotube (SWCNT)-based chemiresistors are reported for a highly robust and sensitive gas sensor to selectively detect cyclohexanone, a target analyte for explosive detection. The trifunctional selector has three important properties: it noncovalently functionalizes SWCNTs with cofacial π-π interactions, it binds to cyclohexanone via hydrogen bond (mechanistic studies were investigated), and it improves the overall robustness of SWCNT-based chemiresistors (e.g., humidity and heat). Our sensors produced reversible and reproducible responses in less than 30 s to 10 ppm of cyclohexanone and displayed an average theoretical limit of detection (LOD) of 5 ppm. PMID:23886453

  4. Purification of single-wall carbon nanotubes by using ultrafine gold particles

    NASA Astrophysics Data System (ADS)

    Nihey, Fumiyuki; Mizoguti, Eiji; Yudasaka, Masako; Iijima, Sumio; Ichihashi, Toshinari; Nakamura, Kazuo

    2000-03-01

    The purification of single-wall carbon nanotubes (SWNTs) is needed to enable detailed characterization and some application of this material. We report a purification method utilizing ultrafine gold particles as catalysts to selectively oxidize carbonaceous impurities in SWNT soot. The ultrafine gold particles with a diameter of 20 nm were dispersed in the soot in combination with benzalkonium chloride as surfactant. Thermogravimetric analyses and electron microscopy observations revealed that oxidation occured at about 330^circC for carbonaceous impurities and at about 410^circC for SWNTs. This selective oxidation enabled us to purify SWNTs and make the quantitative analyses of SWNTs.

  5. Electronic modulations in a single wall carbon nanotube induced by the Au(111) surface reconstruction

    SciTech Connect

    Clair, Sylvain; Shin, Hyung-Joon; Kim, Yousoo E-mail: maki@riken.jp; Kawai, Maki E-mail: maki@riken.jp

    2015-02-02

    The structural and electronic structure of single wall carbon nanotubes adsorbed on Au(111) has been investigated by low-temperature scanning tunneling microscopy and spectroscopy. The nanotubes were dry deposited in situ in ultrahigh vacuum onto a perfectly clean substrate. In some cases, the native herringbone reconstruction of the Au(111) surface interacted directly with adsorbed nanotubes and produced long-range periodic oscillations in their local density of states, corresponding to charge transfer modulations along the tube axis. This effect, however, was observed not systematically for all tubes and only for semiconducting tubes.

  6. Molecular adsorption study of nicotine and caffeine on single-walled carbon nanotubes from first principles

    NASA Astrophysics Data System (ADS)

    Lee, Hyung-June; Kim, Gunn; Kwon, Young-Kyun

    2013-08-01

    Using first-principles calculations, we investigate the electronic structures and binding properties of nicotine and caffeine adsorbed on single-walled carbon nanotubes to determine whether CNTs are appropriate for filtering or sensing nicotine and caffeine molecules. We find that caffeine adsorbs more strongly than nicotine. The different binding characteristics are discussed by analyzing the modification of the electronic structure of the molecule-adsorbed CNTs. We also calculate the quantum conductance of the CNTs in the presence of nicotine or caffeine adsorbates and demonstrate that the influence of caffeine is stronger than nicotine on the conductance of the host CNT.

  7. In Vivo Delivery of Nitric Oxide-Sensing, Single-Walled Carbon Nanotubes

    PubMed Central

    Iverson, Nicole M; Strano, Michael S; Wogan, Gerald N

    2015-01-01

    Detection of nitric oxide (NO) in vivo by single walled carbon nanotubes (SWNT) is based on the fluorescent properties of SWNT and the ability of NO to quench the fluorescence signal. Alterations of the signal can be utilized to detect a small molecule in vivo that has not previously been possible by other assay techniques. The protocols described here explain the techniques used to prepare NO-detecting SWNTs and to administer them to mice by both intravenous and subcutaneous routes. These techniques can also be utilized with other SWNT sensors as well as non-SWNT sensors. PMID:26344235

  8. Influence of Single-Walled Carbon Nanotubes on Thermal Expansion of Water

    NASA Astrophysics Data System (ADS)

    Korolovych, V. F.; Bulavin, L. A.; Prylutskyy, Yu. I.; Khrapatiy, S. V.; Tsierkezos, N. G.; Ritter, U.

    2014-01-01

    This article reports the results of an investigation of the influence of single-walled carbon nanotubes (SWCNTs) functionalized with carboxyl groups on PVT data of water. Specifically, the impact of an aqueous suspension of SWCNTs (maximum concentration of 3.0 mg mL) on the isobaric thermal expansion of water in the temperature and pressure ranges of 293 K to 342 K and 0.1 MPa to 152.3 MPa, respectively, was investigated. The obtained results are discussed in terms of different structures of water confined inside and outside SWCNTs.

  9. A Facile High-speed Vibration Milling Method to Water-disperse Single- walled Carbon Nanohorns

    SciTech Connect

    Shu, Chunying; Zhang, Jianfei; Sim, Jae Hyun; Burke, Brian; Williams, Keith A; Rylander, Nichole M; Campbell, Tom; Puretzky, Alexander A; Rouleau, Christopher M; Geohegan, David B; More, Karren Leslie; Esker, Alan R; Gibson, Harry W; Dorn, Harry C

    2010-01-01

    A high-speed vibration milling (HSVM) method was applied to synthesize water dispersible single- walled carbon nanohorns (SWNHs). Highly reactive free radicals (HOOCCH2CH2 ) produced from an acyl peroxide under HSVM conditions react with hydrophobic SWNHs to produce a highly water dispersible derivative (f-SWNHs), which has been characterized in detail by spectroscopic and microscopic techniques together with thermogravimetric analysis (TGA) and dynamic light scatter- ing (DLS). The carboxylic acid functionalized, water-dispersible SWNHs material are versatile precursors that have potential applications in the biomedical area.

  10. Transmission electron microscopy observations of fracture of single-wall carbon nanotubes under axial tension

    NASA Astrophysics Data System (ADS)

    Lourie, O.; Wagner, H. D.

    1998-12-01

    Well-aligned bundles of single-wall carbon nanotubes under tensile stresses were observed to fracture in real-time by transmission electron microscopy. The expansion of elliptical holes in the polymer matrix results in a tensile force in bridging nanotubes. The polymer matrix at both ends of the bundles deforms extensively under the tension force, and fracture of the nanotubes occurs in tension within the polymer hole region rather than in shear within the gripping polymer region at the ends of the bundles. This provides evidence of significant polymer-nanotube wetting and interfacial adhesion.

  11. Determination of electronic states of individually dissolved ( n, m) single-walled carbon nanotubes in solution

    NASA Astrophysics Data System (ADS)

    Tanaka, Yasuhiko; Hirayama, Kohei; Niidome, Yasuro; Nakashima, Naotoshi

    2009-11-01

    Solution redox chemistry is useful to understand the chirality-dependent electronic properties of single-walled carbon nanotubes (SWNTs). We have found that the electron transfer reactions of sodium dithionite with SWNTs cause photoluminescence (PL) quenching processes of 14 individually dissolved SWNTs in an aqueous micellar solution. Based on the analysis using the Nernst equation for the PL change, we have determined the conduction band ( c1) levels of the 14 isolated SWNTs. We have also estimated the valence band ( ν1) levels as well as the Fermi levels of the SWNTs using the reported bandgap values of the corresponding isolated SWNTs.

  12. Temperature effects in the Raman spectra of bundled single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Meletov, K. P.; Krestinin, A. V.; Arvanitidis, J.; Christofilos, D.; Kourouklis, G. A.

    2009-08-01

    Bundled single-walled carbon nanotubes (SWCNTs) were studied as a function of temperature by means of Raman spectroscopy. The Raman modes exhibit negative temperature shift, reversible for the G band and partially irreversible for the radial breathing modes (RBMs). The softening of the latter is larger for larger diameter tubes, resulting in a better separation of the RBMs after high temperature treatment (HTT). The RBM residual softening vs. treatment temperature demonstrates threshold-like behavior. The temperature-induced changes may be associated with an irreversible weakening of the tube-tube (intertube) interaction possibly due to adsorbent removal or destruction of random intertube C-C bonds.

  13. Diameter-dependent bending dynamics of single-walled carbon nanotubes in liquids

    PubMed Central

    Fakhri, Nikta; Tsyboulski, Dmitri A.; Cognet, Laurent; Weisman, R. Bruce; Pasquali, Matteo

    2009-01-01

    By relating nanotechnology to soft condensed matter, understanding the mechanics and dynamics of single-walled carbon nanotubes (SWCNTs) in fluids is crucial for both fundamental and applied science. Here, we study the Brownian bending dynamics of individual chirality-assigned SWCNTs in water by fluorescence microscopy. The bending stiffness scales as the cube of the nanotube diameter and the shape relaxation times agree with the semiflexible chain model. This suggests that SWCNTs may be the archetypal semiflexible filaments, highly suited to act as nanoprobes in complex fluids or biological systems. PMID:19706503

  14. Molecular dynamics simulation for flow characteristics in nanochannels and single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yasuoka, H.; Imae, T.; Kaneda, M.; Suga, K.

    2014-08-01

    Flows in graphite-, diamond- and silicon-walled nanochannels are discussed by performing molecular dynamics simulations. Flows in carbon nanotubes (CNTs) and graphene- walled nanochannels are also investigated. It is found that the flow rate in the graphite-walled channel tends to be the largest because of its slippery wall structure by the short bond length and the high molecular density of the CNTs. The flow rate in the single walled CNT at a very narrow diameter tends to increase although such a tendency is not seen in the graphene-walled channel.

  15. Transparent and flexible high-performance supercapacitors based on single-walled carbon nanotube films

    NASA Astrophysics Data System (ADS)

    Kanninen, Petri; Dang Luong, Nguyen; Hoang Sinh, Le; Anoshkin, Ilya V.; Tsapenko, Alexey; Seppälä, Jukka; Nasibulin, Albert G.; Kallio, Tanja

    2016-06-01

    Transparent and flexible energy storage devices have garnered great interest due to their suitability for display, sensor and photovoltaic applications. In this paper, we report the application of aerosol synthesized and dry deposited single-walled carbon nanotube (SWCNT) thin films as electrodes for an electrochemical double-layer capacitor (EDLC). SWCNT films exhibit extremely large specific capacitance (178 F g‑1 or 552 μF cm‑2), high optical transparency (92%) and stability for 10 000 charge/discharge cycles. A transparent and flexible EDLC prototype is constructed with a polyethylene casing and a gel electrolyte.

  16. Quantum Ion-Acoustic Oscillations in Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Khan, S. A.; Iqbal, Z.; Wazir, Z.; Aman-ur-Rehman

    2016-05-01

    Quantum ion-acoustic oscillations in single-walled carbon nanotubes are studied by employing a quantum hydrodynamics model. The dispersion equation is obtained by Fourier transformation, which exhibits the existence of quantum ion-acoustic wave affected by change of density balance due to presence of positive or negative heavy species as stationary ion clusters and wave potential at equilibrium. The numerical results are presented, and the role of quantum degeneracy, nanotube geometry, electron exchange-correlation effects, and concentration and polarity of heavy species on wave dispersion is pointed out for typical systems of interest.

  17. Midgap luminescence centers in single-wall carbon nanotubes created by ultraviolet illumination

    NASA Astrophysics Data System (ADS)

    Iakoubovskii, Konstantin; Minami, Nobutsugu; Kim, Yeji; Miyashita, Kanae; Kazaoui, Said; Nalini, Balakrishnan

    2006-10-01

    The authors report the effect of ultraviolet (UV) illumination on optical properties of single-wall carbon nanotubes (SWCNTs) isolated using various dispersants. It is demonstrated that even weak UV light (˜1mW/cm2) can irreversibly alter the SWCNT structure, thus resulting in the emergence of hitherto unknown, redshifted photoluminescence (PL) peaks with concomitant reduction in some of the original PL peaks. These UV-induced changes are characterized in detail and attributed to the creation of midgap PL centers.

  18. Thermoelectric properties of single-wall carbon nanotube films: Effects of diameter and wet environment

    NASA Astrophysics Data System (ADS)

    Hayashi, Daisuke; Ueda, Tomohiro; Nakai, Yusuke; Kyakuno, Haruka; Miyata, Yasumitsu; Yamamoto, Takahiro; Saito, Takeshi; Hata, Kenji; Maniwa, Yutaka

    2016-02-01

    The Seebeck coefficient S and the electrical resistivity ρ of single-wall carbon nanotube (SWCNT) films were investigated as a function of the SWCNT diameter and carrier concentration. The S and ρ significantly changed in humid environments through p-type carrier doping. Experiments, combined with theoretical simulations based on the non-equilibrium Green’s function theory, indicated that the power factor P can be increased threefold by the enrichment of semiconducting SWCNTs, but the nanotube diameter has little effect. The improvement of the film resistivity strongly enhances the film thermoelectric performance, manifested as increasing the value of P above 1200 µW/(m·K2).

  19. Self-assemblies of cationic porphyrins with functionalized water-soluble single-walled carbon nanotubes.

    PubMed

    Kubát, Pavel; Lang, Kamil; Jandal, Pavel; Frank, Ota; Matulková, Irena; Sýkora, Jan; Civis, Svatopluk; Hof, Martin; Kavan, Ladislav

    2009-10-01

    5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin, 5,10,15,20-tetrakis(2-N-methylpyridyl)porphyrin, and 5,10,15,20-tetrakis(4-trimethylammoniophenyl)porphyrin form self-assemblies with single-walled carbon nanotubes (SWNT) functionalized by polyaminobenzene sulfonic acid. Both steady-state and time-resolved emission studies revealed efficient quenching of the excited singlet states of the porphyrins. Atomic force microscopy, fluorescence confocal microscopy, and fluorescence lifetime imaging allowed the visualization of individual bundles of SWNTs and the differentiation of porphyrin molecules at specific binding sites of SWNT. PMID:19908455

  20. Microwave-induced electrophilic addition of single-walled carbon nanotubes with alkylhalides

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Wang, Xianbao; Tian, Rong; Li, Shaoqing; Wan, Li; Li, Mingjian; You, Haijun; Li, Qin; Wang, Shimin

    2008-02-01

    We report the microwave-induced electrophilic addition of single-walled carbon nanotubes (SWNTs) with alkylhalides using Lewis acid as a catalyst followed by hydrolysis. The reaction results in the attachment of alkyl and hydroxyl groups to the surface of the nanotubes. This rapid and high-energy microwave radiation is found to be highly efficient for this reaction, which only needs as low as several minutes. The resulting nanotubes were characterized with FTIR, UV-vis-NIR, Raman, TGA, TEM and AFM. It demonstrates that iodo-alkanes show higher reaction activity with SWNTs than chloro- and bromo-alkanes.

  1. The compressive buckling and size effect of single-walled carbon nanotubes

    SciTech Connect

    Sun, Yuzhou Zhu, Yanzhi; Li, Dongxia

    2015-03-10

    A higher-order Bernoulli-Euler beam model is developed to investigate the compressive buckling and size effect of single-walled carbon nanotubes by using a higher-order continuum relationship that has been previously proposed by the present authors. The second-order deformation gradients with respect to the axial direction are also considered, and the beam parameters are obtained by calculating the constitutive response around the circumference. The critical compressive force is analytically provided, and the size effect is studied by estimating the contribution of the higher-order terms.

  2. Transparent and flexible high-performance supercapacitors based on single-walled carbon nanotube films.

    PubMed

    Kanninen, Petri; Luong, Nguyen Dang; Sinh, Le Hoang; Anoshkin, Ilya V; Tsapenko, Alexey; Seppälä, Jukka; Nasibulin, Albert G; Kallio, Tanja

    2016-06-10

    Transparent and flexible energy storage devices have garnered great interest due to their suitability for display, sensor and photovoltaic applications. In this paper, we report the application of aerosol synthesized and dry deposited single-walled carbon nanotube (SWCNT) thin films as electrodes for an electrochemical double-layer capacitor (EDLC). SWCNT films exhibit extremely large specific capacitance (178 F g(-1) or 552 μF cm(-2)), high optical transparency (92%) and stability for 10 000 charge/discharge cycles. A transparent and flexible EDLC prototype is constructed with a polyethylene casing and a gel electrolyte. PMID:27122323

  3. Electronic properties of single-walled carbon nanotubes filled with manganese halogenides

    NASA Astrophysics Data System (ADS)

    Kharlamova, M. V.

    2016-09-01

    In this work, single-walled carbon nanotubes (SWCNTs) were filled with manganese chloride and manganese bromide by a capillary filling method. The electronic properties of the filled SWCNTs were investigated by Raman spectroscopy and X-ray photoelectron spectroscopy. It was found that the encapsulated manganese halogenides led to hole doping of the SWCNTs due to the charge transfer from the nanotubes to the encapsulated compounds. The embedded MnCl2 had stronger doping effect on the SWCNTs than MnBr2.

  4. Size effect in the tensile fracture of single-walled carbon nanotubes with defects

    NASA Astrophysics Data System (ADS)

    Yang, M.; Koutsos, V.; Zaiser, M.

    2007-04-01

    Molecular simulation is used to determine the fracture strength of single-walled carbon nanotubes (SWNT) containing different concentrations of randomly distributed point defects. The results are analysed using Weibull statistics, and the dependence of the statistical distribution of fracture strengths on defect concentration is established. Arguments from extreme order statistics are then used to formulate a relationship between the length of SWNT and their fracture strength. The results of this investigation help to explain the large differences between SWNT fracture strengths measured in experiments (13-52 GPa) and those obtained from theoretical calculations assuming defect-free nanotubes (~185 GPa).

  5. Fine Structure of the Low-Frequency Raman Phonon Bands of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Iliev, M. N.; Litvinchuk, A. P.; Arepalli, S.; Nikolaev, P.; Scott, C. D.

    1999-01-01

    The Raman spectra of singled-wall carbon nanotubes (SWNT) produced by laser and are process were studied between 5 and 500 kappa. The line width vs. temperature dependence of the low-frequency Raman bands between 150 and 200/ cm deviates from that expected for phonon decay through phonon-phonon scattering mechanism. The experimental results and their analysis provided convincing evidence that each of the low-frequency Raman lines is a superposition of several narrower Raman lines corresponding to tubes of nearly the same diameter. The application of Raman spectroscopy to probe the distribution of SWNT by both diameter and chirality is discussed.

  6. Stable double helical iodine chains inside single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yao, Zhen; Liu, Chun-Jian; Lv, Hang; Liu, Bing-Bing

    2016-08-01

    The helicity of stable double helical iodine chains inside single-walled carbon nanotubes (SWCNTs) is studied by calculating the systematic interaction energy. Our results present clear images of stable double helical structures inside SWCNTs. The optimum helical radius and helical angle increase and decrease with increasing diameter, respectively. The tube's diameter plays a leading role in the helicity of encapsulated structures, while the tube's chirality may induce different metastable structures. This study indicates that the observed double helical iodine chains in experiments are not necessarily the optimum structures, but may also be metastable structures.

  7. Detecting the formation of single-walled carbon nanotube rings by photoabsorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hida, Akira; Suzuki, Takayuki; Ishibashi, Koji

    2016-08-01

    Photoabsorption spectroscopy was conducted on single-walled carbon nanotubes (SWNTs) during the formation of ring structures. The absorption bands observed before starting the formation gradually shifted while broadening in the middle. When they finally disappeared, it was found, via atomic force microscopy observations, that almost all SWNTs were transformed into rings. The spectral changes were assumed to be due to the changes in the electronic states of SWNTs. This idea was supported by the results of an investigation using a scanning tunneling microscope. It could be said that photoabsorption spectroscopy is useful for detecting ring formation in situ.

  8. Pore structure of raw and purified HiPco single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cinke, Martin; Li, Jing; Chen, Bin; Cassell, Alan; Delzeit, Lance; Han, Jie; Meyyappan, M.

    2002-10-01

    Very high purity single-walled carbon nanotubes (SWNTs) were obtained from HiPco SWNT samples containing Fe particles by a two-step purification process. The raw and purified samples were characterized using high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and thermogravimetric analysis (TGA). The purified sample consists of ˜0.4% Fe and the process does not seem to introduce any additional defects. The N 2 adsorption isotherm studies at 77 K reveal that the total surface area of the purified sample increases to 1587 m 2/g from 567 m 2/g for the raw material, which is the highest value reported for SWNTs.

  9. Periodic alignment of Si quantum dots on hafnium oxide coated single wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Olmedo, Mario; Martinez-Morales, Alfredo A.; Liu, Gang; Yengel, Emre; Ozkan, Cengiz S.; Lau, Chun Ning; Ozkan, Mihrimah; Liu, Jianlin

    2009-03-01

    We demonstrate a bottom up approach for the aligned epitaxial growth of Si quantum dots (QDs) on one-dimensional (1D) hafnium oxide (HfO2) ridges created by the growth of HfO2 thin film on single wall carbon nanotubes. This growth process creates a high strain 1D ridge on the HfO2 film, which favors the formation of Si seeds over the surrounding flat HfO2 area. Periodic alignment of Si QDs on the 1D HfO2 ridge was observed, which can be controlled by varying different growth conditions, such as growth temperature, growth time, and disilane flow rate.

  10. Functionalization of single-walled carbon nanotubes with uracil, guanine, thymine and L-alanine

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    Experimental investigation of functionalization of oxidized single-walled carbon nanotubes (OSWCNTs) with three nucleic acid bases such as uracil, guanine, thymine and one amino acid, L-alanine is carried out. Initially, the SWCNTs are oxidized by acid treatment. Further, the oxidized SWCNTs are effectively functionalized with aforementioned biological compounds by ultrasonication. The diameter of OSWCNTs has increased after the adsorption of biological compounds. The cumulative Π-Π stacking, hydrogen bond and polar interaction are the key factors to realize the adsorption. The amount of adsorption of each biological compound is estimated. The adsorption of guanine is more among all the four biological compounds.

  11. In situ Raman monitoring of single-walled carbon nanotube filling with copper chloride

    NASA Astrophysics Data System (ADS)

    Eremin, Timofei V.; Tonkikh, Alexander A.; Kudryashova, Ekaterina M.

    2016-03-01

    In situ characterization of single-walled carbon nanotubes during their gas-phase filling with copper chloride (CuCl) was performed with Raman spectroscopy. The time dependence of positions and intensities of G, 2D, and radial breathing modes was investigated. It was demonstrated that the adsorption of copper chloride from gas phase on the external and internal surfaces of nanotubes leads to the Raman mode shifting. However, this effect is weaker than in case of formation of one-dimensional CuCl crystals inside nanotubes.

  12. Kinetics of reactive ion etching upon single-walled carbon nanotubes

    SciTech Connect

    Kato, Toshiaki; Hatakeyama, Rikizo

    2008-01-21

    The remarkable etching reaction of single-walled carbon nanotubes (SWNTs) has been observed in their growth of the parameter-controlled plasma chemical vapor deposition (CVD). The time evolution study of the SWNTs growth leads to establishing a growth equation which can completely express the growth kinetics of SWNTs in the plasma CVD. The growth equation is found to reveal that there are several key parameters which directly affect the etching reaction of SWNTs. Furthermore, such kinetics of the SWNT etching in plasmas can perfectly be explained with a reactive ion etching model.

  13. Synthesis and chemical modification of single-walled carbon nanotubes and inorganic nanowires

    NASA Astrophysics Data System (ADS)

    Zheng, Bo

    This dissertation describes the study of single-walled carbon nanotubes (SWNTs), inorganic nanowires, and carbon aerogels. A novel catalyst of iron/molybdenum nanoparticles supported on alumina aerogel was developed for CVD synthesis of SWNTs. Using this catalyst, the yield of SWNTs was enhanced by at least three times compared to previously reported best results. The highest yield of SWNTs was achieved when the reaction temperature was between 850°C and 900°C with CO (˜1000 sccm) as feeding gas. A combination of acid wash and mild oxidation processes was used to purify tire raw SWNT product. Transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) indicated that the majority (>90%) of the purified product was SWNTs. The purified SWNTs were fluorinated by diluted fluorine gas at 250°C. It was found that F-SWNTs could be recovered at an annealing temperature as low as 100°C. The thermal recovery behaviors of metallic and semiconducting SWNTs were very similar at annealing temperature ≥150°C, as suggested by 2D UV-Vis-NIR correlation spectroscopy. F-SWNTs were also added into poly(ethylene oxide) (PEO) to form a PEO/F-SWNT composite. Mechanical properties measurements showed that the F-SWNTs significantly increased the strength of the resulting composite. A highly efficient method of SWNT synthesis on surfaces was also developed. It was found that the combination of carbon monoxide and hydrogen as a feeding gas greatly enhanced the surface growth of SWNTs. This method showed a large window of optimal HZ concentration (20%--80%) and synthesis temperature (800--900°C), so the result was very reproducible. In the second project, two novel methods of preparing silicon oxide and tungsten oxide nanowires, respectively, were developed. By using a millimeter-sized liquid gallium ball as a metal solvent at 920--940°C, bulk quantities of ultralong, uniform and well-aligned silicon oxide nanowires were synthesized. XPS and EDX indicated that the

  14. Flux-Dependent Growth Kinetics and Diameter Selectivity in Single-Wall Carbon Nanotube Arrays

    SciTech Connect

    Geohegan, David B; Puretzky, Alexander A; Jackson, Jeremy Joseph; Rouleau, Christopher M; Eres, Gyula; More, Karren Leslie

    2011-01-01

    The nucleation and growth kinetics of single-wall carbon nanotubes in aligned arrays have been measured using fast pulses of acetylene and in situ optical diagnostics in conjunction with low pressure chemical vapor deposition (CVD). Increasing the acetylene partial pressure is shown to decrease nucleation times by three orders of magnitude, permitting aligned nanotube arrays to nucleate and grow to microns lengths within single gas pulses at high (up to 7 micron/s) peak growth rates and short ~ 0.5 s times.Low-frequency Raman scattering (> 10 cm-1) and transmission electron microscopy measurements show that increasing the feedstock flux in both continuous-CVD and pulsed-CVD shifts the product distribution to large single-wall carbon nanotube diameters > 2.5 nm. Sufficiently high acetylene partial pressures in pulsed-CVD appear to temporarily terminate the growth of the fastest- growing, small-diameter nanotubes by overcoating the more catalytically-active, smaller catalyst nanoparticles within the ensemble with non-nanotube carbon in agreement with a growth model. The results indicate that subsets of catalyst nanoparticle ensembles nucleate, grow, and terminate growth within different flux ranges according to their catalytic activity.

  15. Tethered anthracene pair as molecular tweezers for post-production separation of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Anderson, Ankoma; Yang, Fengchun; Cao, Li; Li, Huaping; Meziani, Mohammed J.; Sun, Ya-Ping

    2016-07-01

    As-produced single-walled carbon nanotubes (SWNTs) are metallic and semiconducting mixtures. An anthracene mono-derivative with a long alkyl tail and a molecule with a tethered pair of anthracene species (bis-anthracene) in a "molecular tweezers"-like configuration were synthesized and evaluated for the separation of SWNTs. While the mono-derivative was incapable of the noncovalent functionalization-solubilization, the bis-anthracene was found to be very effective. The results suggest that molecular tweezers of a tethered pair of planar aromatic species can be coupled with the selection of a suitable solvent or solvent mixture for effective and efficient post-production separation of metallic and semiconducting SWNTs.

  16. Simultaneous shunt protection and back contact formation for CdTe solar cells with single wall carbon nanotube layers

    NASA Astrophysics Data System (ADS)

    Phillips, Adam B.; Khanal, Rajendra R.; Song, Zhaoning; Watthage, Suneth C.; Kormanyos, Kenneth R.; Heben, Michael J.

    2015-12-01

    Thin film photovoltaic (PV) devices and modules prepared by commercial processes can be severely compromised by through-device low resistance electrical pathways. The defects can be due to thin or missing semiconductor material, metal diffusion along grain boundaries, or areas containing diodes with low turn-on potentials. We report the use of single wall carbon nanotube (SWCNT) layers to enable both protection against these defects and back contact formation for CdTe PV devices. Samples prepared with a SWCNT back contact exhibited good efficiency and did not require shunt protection, while devices prepared without shunt protection using a standard metal back contact performed poorly. We describe the mechanism by which the SWCNT layer functions. In addition to avoiding the need for shunt protection by other means, the SWCNT film also provides a route to higher short circuit currents.

  17. Spectroelectrochemical properties of the single walled carbon nanotubes functionalized with polydiphenylamine doped with heteropolyanions

    SciTech Connect

    Smaranda, I.; Baibarac, M.; Baltog, I.; Mevellec, J.Y.; Lefrant, S.

    2013-01-15

    A combined chemical-electrochemical method was used for covalent functionalization of single-walled carbon nanotube (SWNT) with polydiphenylamine (PDPA) doped with heteropolyanions of H{sub 3}PMo{sub 12}O{sub 40}{center_dot}xH{sub 2}O. The functionalization process induces in Raman spectra of SWNTs the following changes: (i) an increase in relative intensity of the D band, accompanied a gradual up-shift of the G band in the case of the semiconducting tubes and a decrease in the relative intensity of band peaked at 1540 cm{sup -1} is remarked in the case of the metallic tubes; (ii) in the anti-Stokes Raman spectrum an increase in the relative intensity of Raman line of metallic tubes peaked at -1560 cm{sup -1} is remarked when the cycles number increases. The additional down-shift of the FTIR bands belonging to H{sub 3}PMo{sub 12}O{sub 40} heteropolyanions (at 881, 943 and 1055 cm{sup -1}) and PDPA (at 688, 736 and 1016 cm{sup -1}) originates in hindrance steric effects induced the covalent functionalization of SWNTs with polymer molecules. Using Raman scattering and FTIR spectroscopy we demonstrate that chemical polymerization of diphenylamine in the presence of H{sub 3}PMo{sub 12}O{sub 40}{center_dot}xH{sub 2}O and SWNTs results in a composite of the type blend based on PDPA in un-doped state and SWNTs doped with H{sub 3}PMo{sub 12}O{sub 40} heteropolyanions. - Graphical abstract: Stokes and anti-Stokes Raman spectra of the SWNTs before (a) and after electrochemical functionalization with PDPA doped with heteropolyanions by 5 (b) and 25 (c) voltammeter cycles. Highlights: Black-Right-Pointing-Pointer A chemical-electrochemical method is used to functionalization of SWNTs. Black-Right-Pointing-Pointer Functionalization of wall-side of tube is evidenced by anti-Stokes Raman studies. Black-Right-Pointing-Pointer FTIR spectra proves insertion of heteropolyanions in polydiphenylamine matrix. Black-Right-Pointing-Pointer FTIR spectra of polymer functionalized SWNTs

  18. Fabrication, characterization and modeling of single-walled carbon nanotube films for device applications

    NASA Astrophysics Data System (ADS)

    Behnam, Ashkan

    The main goal of this dissertation was to study electrical properties of single-walled carbon nanotube (CNT) films as new conductive and transparent materials. First, the ability to efficiently pattern CNT films with good selectivity and directionality down to submicron lateral dimensions by photolithography or e-beam lithography and oxygen plasma etching was demonstrated and the effect of etch parameters on the nanotube film etch rate and selectivity was studied. Then by fabricating standard four-point-probe structures using this technique, it was demonstrated that the resistivity of the films increases over three orders of magnitude as their width and thickness shrink close to the percolation threshold. A Monte Carlo simulation platform was then developed to model percolating conduction in CNT films, which could fit the experimental results and confirm the strong scaling of resistivity with various nanotube and device parameters. These experimental and computational capabilities were then used to study the 1/f noise behavior in CNT films. The results from the computational calculations were in good agreement with previous experiments. It was shown that the 1/fnoise amplitude depends strongly on both device dimensions and on the film resistivity. The variation of resistivity and 1/fnoise as a function of temperature was then studied experimentally and it was concluded that at very low temperatures 3D variable range hopping was the dominant mechanism for both. At 40 K and above, however, the fluctuation induced tunneling model explained the resistivity behavior and the fluctuations within or at the surface of the SiO2 substrate underneath the CNT film were the probable dominant source of the noise in this regime. Finally, metal semiconductor-metal photodetectors were fabricated based on CNT film-Gallium Arsenide (GaAs) and CNT film-Silicon(Si) Schottky contacts to show the application of CNT film in optoelectronic devices. The Schottky barrier heights of CNT film

  19. Chemical vapor deposition growth of single-walled carbon nanotubes with controlled structures for nanodevice applications.

    PubMed

    Chen, Yabin; Zhang, Jin

    2014-08-19

    Single-walled carbon nanotubes (SWNTs), a promising substitute to engineer prospective nanoelectronics, have attracted much attention because of their superb structures and physical properties. The unique properties of SWNTs rely sensitively on their specific chiral structures, including the diameters, chiral angles, and handedness. Furthermore, high-performance and integrated circuits essentially require SWNT samples with well-aligned arrays, of single conductive type and of pure chirality. Although much effort has been devoted to chemical vapor deposition (CVD) growth of SWNTs, their structure control, growth mechanism, and structural characterizations are still the primary obstacles for the fabrication and application of SWNT-based nanodevices. In this Account, we focus on our established CVD growth methodology to fulfill the requirements of nanodevice applications. A rational strategy was successfully exploited to construct complex architectures, selectively enrich semiconducting (s) or metallic (m) SWNTs, and control chirality. First, well-aligned and highly dense SWNT arrays are beneficial for nanodevice integration. For the directed growth mode, anisotropic interactions between the SWNTs and the crystallographic structure of substrate are crucial for their growth orientation. Just as crystals possess various symmetries, SWNTs with controlled geometries have the corresponding turning angles. Their complex architectures come from the synergetic effect of lattice and gas flow directed modes. Especially, the aligned orientations of SWNTs on graphite are chirality-selective, and their chiral angles, handedness, and (n,m) index have been conveniently and accurately determined. Second, UV irradiation and sodium dodecyl sulfate (SDS) washing-off methods have been explored to selectively remove m-SWNTs, leaving only s-SWNT arrays on the surface. Moreover, the UV-assisted technique takes the advantages of low cost and high efficiency and it directly produces a high

  20. Light emission and degradation of single-walled carbon nanotube filament

    NASA Astrophysics Data System (ADS)

    Zhao, Z. G.; Li, F.; Liu, C.; Cheng, H. M.

    2005-08-01

    Household light bulbs were fabricated using macroscopically long and aligned single-walled carbon nanotube (SWNT) ropes as filaments. It was found that the SWNT filament could emit bright light when an electric current was passed through it. The light spectrum from the SWNT filament showed a nonblackbody characteristic of the thermal emission, and its infrared emission was almost completely suppressed possibly due to the "photonic band-gap" effect that originates in the loose fibrous bundle structure of the SWNT filament. The electrical resistance of the SWNT filament was found to first increase, and then continually decrease during light emission. It was also found that an electric current could cause degradation and burnout of the SWNT filament and result in complete amorphization, and that an interesting mushroomlike carbon structure was formed due to the carbon evaporation of the nanotube filament during light emission.

  1. XPS Protocol for the Characterization of Pristine and Functionalized Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Sosa, E. D.; Allada, R.; Huffman, C. B.; Arepalli, S.

    2009-01-01

    Recent interest in developing new applications for carbon nanotubes (CNT) has fueled the need to use accurate macroscopic and nanoscopic techniques to characterize and understand their chemistry. X-ray photoelectron spectroscopy (XPS) has proved to be a useful analytical tool for nanoscale surface characterization of materials including carbon nanotubes. Recent nanotechnology research at NASA Johnson Space Center (NASA-JSC) helped to establish a characterization protocol for quality assessment for single wall carbon nanotubes (SWCNTs). Here, a review of some of the major factors of the XPS technique that can influence the quality of analytical data, suggestions for methods to maximize the quality of data obtained by XPS, and the development of a protocol for XPS characterization as a complementary technique for analyzing the purity and surface characteristics of SWCNTs is presented. The XPS protocol is then applied to a number of experiments including impurity analysis and the study of chemical modifications for SWCNTs.

  2. Electron paramagnetic resonance investigation of purified catalyst-free single-walled carbon nanotubes.

    PubMed

    Zaka, Mujtaba; Ito, Yasuhiro; Wang, Huiliang; Yan, Wenjing; Robertson, Alex; Wu, Yimin A; Rümmeli, Mark H; Staunton, David; Hashimoto, Takeshi; Morton, John J L; Ardavan, Arzhang; Briggs, G Andrew D; Warner, Jamie H

    2010-12-28

    Electron paramagnetic resonance of single-walled carbon nanotubes (SWCNTs) has been bedevilled by the presence of paramagnetic impurities. To address this, SWCNTs produced by laser ablation with a nonmagnetic PtRhRe catalyst were purified through a multiple step centrifugation process in order to remove amorphous carbon and catalyst impurities. Centrifugation of a SWCNT solution resulted in sedimentation of carbon nanotube bundles containing clusters of catalyst particles, while isolated nanotubes with reduced catalyst particle content remained in the supernatant. Further ultracentrifugation resulted in highly purified SWCNT samples with a narrow diameter distribution and almost no detectable catalyst particles. Electron paramagnetic resonance (EPR) signals were detected only for samples which contained catalyst particles, with the ultracentrifuged SWCNTs showing no EPR signal at X-band (9.4 GHz) and fields < 0.4 T. PMID:21082779

  3. Ab-initio calculation of n-doped single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Margine, Elena R.; Crespi, Vincent H.

    2004-03-01

    We study charge-induced changes in shape and electronic structure for n-doped single-walled carbon nanotubes within density functional theory. A certain nearly free electron state is downshifted in the presence of extra electrons. A similar effect has been seen in potassium-doped carbon nanotubes [1], where the downshift was attributed to the hybridization of the nearly free electron state with the K 4s state. In the present calculation the negative charge is neutralized by a uniform positive background, so the downshift must arise from a different effect. The state crosses the Fermi level at a charge per carbon atom of 0.04 for all the tubes studied. Connections are made to recent experiments in the group of P. Eklund.[1]Yoshiyuki Miyamoto, Angel Rubio, X. Blase, Marvin L. Cohen, and Steven G. Louie PRL 74, 2993 (1995)

  4. Selective adsorption of proteins on single-wall carbon nanotubes by using a protective surfactant.

    PubMed

    Knyazev, Anton; Louise, Loïc; Veber, Michèle; Langevin, Dominique; Filoramo, Arianna; Prina-Mello, Adriele; Campidelli, Stéphane

    2011-12-16

    The dispersion of highly hydrophobic carbon materials such as carbon nanotubes in biological media is a challenging issue. Indeed, the nonspecific adsorption of proteins occurs readily when the nanotubes are introduced in biological media; therefore, a methodology to control adsorption is in high demand. To address this issue, we developed a bifunctional linker derived from pyrene that selectively enables or prevents the adsorption of proteins on single-wall carbon nanotubes (SWNTs). We demonstrated that it is possible to decrease or completely suppress the adsorption of proteins on the nanotube sidewall by using proper functionalization (either covalent or noncovalent). By subsequently activating the functional groups on the nanotube derivatives, protein adsorption can be recovered and, therefore, controlled. Our approach is simple, straightforward, and potentially suitable for other biomolecules that contain thio or amino groups available for coupling. PMID:22095560

  5. The first atomistic modelling-aided reproduction of morphologically defective single walled carbon nanohorns.

    PubMed

    Furmaniak, Sylwester; Terzyk, Artur P; Kaneko, Katsumi; Gauden, Piotr A; Kowlaczyk, Piotr; Itoh, Tsutomu

    2013-01-28

    A new modelling-aided approach for the atomistic model of single walled carbon nanohorn (SWNH) creation is presented, based on experimental evidence, on realistic potential of carbon-carbon interactions and on molecular simulations. A new model of SWNHs is next used to predict Ar adsorption properties and to check the molecular fundamentals of the adsorption mechanism. The influence of the apex angle value, nanohorn diameter and nanohorn length on the shapes of isotherms, enthalpy, high resolution α(s)-plots and adsorption potential distribution curves is checked. Finally the comparison with new experimental Ar adsorption results is shown and the conclusions on the porosity of real SWNH aggregates are given. PMID:23229231

  6. Quantum chemistry study on the open end of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hou, Shimin; Shen, Ziyong; Zhao, Xingyu; Xue, Zengquan

    2003-05-01

    Geometrical and electronic structures of open-ended single-walled carbon nanotubes (SWCNTs) are calculated using density functional theory (DFT) with hybrid functional (B3LYP) approximation. Due to different distances between carbon atoms along the edge, reconstruction occurs at the open end of the (4,4) armchair SWCNT, i.e., triple bonds are formed in the carbon atom pairs at the mouth; however, for the (6,0) zigzag SWCNT, electrons in dangling bonds still remain at 'no-bonding' states. The ionization potential (IP) of both (4,4) and (6,0) SWCNTs is increased by their negative intrinsic dipole moments, and localized electronic states existed at both of their open ends.

  7. FAST TRACK COMMUNICATION: Mechanical properties of non-reconstructed defective single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Scarpa, F.; Adhikari, S.; Wang, C. Y.

    2009-07-01

    This paper describes the equivalent homogeneous uniaxial mechanical properties of defective single-wall carbon nanotubes. In particular, non-reconstructed defects that can be produced by ion or electronic irradiation have been considered. A discrete nonlinear finite-element approach based on the mechanical properties of individual carbon-carbon (C-C) bonds has been used. The individual C-C bonds in turn were simulated as beam structural elements. Extensive Monte Carlo based numerical simulation has been reported in the paper. The results show that the homogeneous elastic properties of the defective nanotubes can be qualitatively and quantitatively different from the pristine configurations. The defective nanotubes show a slight reduction in axial stiffness (Young's modulus), but large variations of Poisson's ratio outside the elastic bounds for isotropic materials, depending on the locations of the vacancies. The large fluctuations of Poisson's ratio can lead to extreme positive transversal contractions or to auxetic behaviour when the nanotubes are subjected to tensile loading.

  8. Nerve agent detection using networks of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Novak, J. P.; Snow, E. S.; Houser, E. J.; Park, D.; Stepnowski, J. L.; McGill, R. A.

    2003-11-01

    We report the use of carbon nanotubes as a sensor for chemical nerve agents. Thin-film transistors constructed from random networks of single-walled carbon nanotubes were used to detect dimethyl methylphosphonate (DMMP), a simulant for the nerve agent sarin. These sensors are reversible and capable of detecting DMMP at sub-ppb concentration levels, and they are intrinsically selective against interferent signals from hydrocarbon vapors and humidity. We provide additional chemical specificity by the use of filters coated with chemoselective polymer films. These results indicate that the electronic detection of sub-ppb concentrations of nerve agents and potentially other chemical warfare agents is possible with simple-to-fabricate carbon nanotube devices.

  9. Improving Dispersion of Single-Walled Carbon Nanotubes in a Polymer Matrix Using Specific Interactions

    SciTech Connect

    Rasheed, Asif; Dadmun, Mark D; Ivanov, Ilia N; Britt, Phillip F; Geohegan, David B

    2006-01-01

    A novel approach is presented to improve the dispersion of oxidized single-walled carbon nanotubes (SWNTs) in a copolymer matrix by tuning hydrogen-bonding interactions to enhance dispersion. Nanocomposites of single-walled carbon nanotubes and copolymers of styrene and vinyl phenol (PSVPh) with varying vinyl phenol content were produced and examined. The dispersion of the SWNT in the polymer matrix is quantified by optical microscopy and Raman spectroscopy. Raman spectroscopy is also used to investigate preferred interactions between the SWNTs and the copolymers via the shift in the D* Raman band of the SWNTs in the composites. All composites show regions of SWNT aggregates; however, the aggregate size varies with composition of the PSVPh copolymer and the amount of SWNT oxidation. Optimal dispersion of the SWNT is observed in PSVPh with 20% vinyl phenol and oxidized nanotubes, which correlates with spectroscopic evidence that indicates that this system also incorporates the most interactions between SWNT and polymer matrix. These results are in agreement with previous studies that indicate that optimizing the extent of specific interactions between a polymer matrix and nanoscale filler enables the efficient dispersion of the nanofillers.

  10. Electronic structure of single-walled carbon nanotubes inside helical DNA wraps

    NASA Astrophysics Data System (ADS)

    Snyder, Stacy; Rotkin, Slava

    2007-03-01

    Single stranded DNA can helically wrap a single-walled carbon nanotube (SWNT) leading to changes in electronic structure, which is the subject of our study. Other charged polymers may produce band gap modulation similar to that observed for DNA-SWNT complexes. For these hybrids we assume a regular helical wrap, the potential of which breaks the symmetry of the pristine SWNT. Band structure changes are modeled quantum mechanically using the tight binding method together with self-consistent electrostatics. Gap modulation and band structure symmetry-lowering effects may result in variation of the optical spectra, especially for (slightly forbidden) transverse optical transitions. The effect of environmental screening of charges is investigated. Self-consistent electrostatic calculations yield cohesion energy between a charged, regular wrap and a SWNT of the order of tenths of eV per DNA base [1]. [1] Snyder, S. E., and Rotkin, S. V., Polarization Component of Cohesion Energy in Single-Wall Carbon Nanotube-DNA Complexes, JETP Letters 84, 348 (2006).

  11. Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells

    PubMed Central

    2011-01-01

    Herein we are the first to report that single-walled carbon nanotubes (SWCNTs) exhibit dual-phase regulation to Arabidopsis mesophyll cells exposed to different concentration of SWCNTs. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 h, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS) generation was measured. Partial protoplasts were stained with propidium iodide and 4'-6- diamidino-2-phenylindole, partial protoplasts were incubated with fluorescein isothiocyanate-labeled SWCNTs, and observed by fluorescence microscopy. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' necrosis and apoptosis. In conclusion, single walled carbon nanotubes can get through Arabidopsis mesophyll cell wall and membrane, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts such as low dose stimulating cell growth, and high dose inducing cells' ROS generation, necrosis or apoptosis.

  12. Comparative Dynamics and Sequence Dependence of DNA and RNA Binding to Single Walled Carbon Nanotubes

    PubMed Central

    Landry, Markita P.; Vuković, Lela; Kruss, Sebastian; Bisker, Gili; Landry, Alexandra M.; Islam, Shahrin; Jain, Rishabh; Schulten, Klaus; Strano, Michael S.

    2015-01-01

    Noncovalent polymer-single walled carbon nanotube (SWCNT) conjugates have gained recent interest due to their prevalent use as electrochemical and optical sensors, SWCNT-based therapeutics, and for SWCNT separation. However, little is known about the effects of polymer-SWCNT molecular interactions on functional properties of these conjugates. In this work, we show that SWCNT complexed with related polynucleotide polymers (DNA, RNA) have dramatically different fluorescence stability. Surprisingly, we find a difference of nearly 2500-fold in fluorescence emission between the most fluorescently stable DNA-SWCNT complex, C30 DNA-SWCNT, compared to the least fluorescently stable complex, (AT)7A-(GU)7G DNA-RNA hybrid-SWCNT. We further reveal the existence of three regimes in which SWCNT fluorescence varies nonmonotonically with SWCNT concentration. We utilize molecular dynamics simulations to elucidate the conformation and atomic details of SWCNT-corona phase interactions. Our results show that variations in polynucleotide sequence or sugar backbone can lead to large changes in the conformational stability of the polymer SWCNT corona and the SWCNT optical response. Finally, we demonstrate the effect of the coronae on the response of a recently developed dopamine nanosensor, based on (GT)15 DNA- and (GU)15 RNA-SWCNT complexes. Our results clarify several features of the sequence dependence of corona phases produced by polynucleotides adsorbed to single walled carbon nanotubes, and the implications for molecular recognition in such phases. PMID:26005509

  13. Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells

    NASA Astrophysics Data System (ADS)

    Yuan, Hengguang; Hu, Shanglian; Huang, Peng; Song, Hua; Wang, Kan; Ruan, Jing; He, Rong; Cui, Daxiang

    2011-12-01

    Herein we are the first to report that single-walled carbon nanotubes (SWCNTs) exhibit dual-phase regulation to Arabidopsis mesophyll cells exposed to different concentration of SWCNTs. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 h, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS) generation was measured. Partial protoplasts were stained with propidium iodide and 4'-6- diamidino-2-phenylindole, partial protoplasts were incubated with fluorescein isothiocyanate-labeled SWCNTs, and observed by fluorescence microscopy. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' necrosis and apoptosis. In conclusion, single walled carbon nanotubes can get through Arabidopsis mesophyll cell wall and membrane, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts such as low dose stimulating cell growth, and high dose inducing cells' ROS generation, necrosis or apoptosis.

  14. Structural stability of transparent conducting films assembled from length purified single-wall carbon nanotubes

    SciTech Connect

    J. M. Harris; G. R. S. Iyer; D. O. Simien; J. A. Fagan; J. Y. Huh; J. Y. Chung; S. D. Hudson; J. Obrzut; J. F. Douglas; C. M. Stafford; E. K. Hobbie

    2011-01-01

    Single-wall carbon nanotube (SWCNT) films show significant promise for transparent electronics applications that demand mechanical flexibility, but durability remains an outstanding issue. In this work, thin membranes of length purified single-wall carbon nanotubes (SWCNTs) are uniaxially and isotropically compressed by depositing them on prestrained polymer substrates. Upon release of the strain, the topography, microstructure, and conductivity of the films are characterized using a combination of optical/fluorescence microscopy, light scattering, force microscopy, electron microscopy, and impedance spectroscopy. Above a critical surface mass density, films assembled from nanotubes of well-defined length exhibit a strongly nonlinear mechanical response. The measured strain dependence reveals a dramatic softening that occurs through an alignment of the SWCNTs normal to the direction of prestrain, which at small strains is also apparent as an anisotropic increase in sheet resistance along the same direction. At higher strains, the membrane conductivities increase due to a compression-induced restoration of conductive pathways. Our measurements reveal the fundamental mode of elasto-plastic deformation in these films and suggest how it might be suppressed.

  15. Global Phospholipidomics Analysis Reveals Selective Pulmonary Peroxidation Profiles Upon Inhalation of Single Walled Carbon Nanotubes

    PubMed Central

    Tyurina, Yulia Y.; Kisin, Elena R.; Murray, Ashley; Tyurin, Vladimir A.; Kapralova, Valentina I.; Sparvero, Louis J.; Amoscato, Andrew A.; Samhan-Arias, Alejandro K.; Swedin, Linda; Lahesmaa, Riitta; Fadeel, Bengt; Shvedova, Anna A.; Kagan, Valerian E.

    2011-01-01

    It is commonly believed that nanomaterials cause non-specific oxidative damage. Our mass spectrometry-based oxidative lipidomics analysis of all major phospholipid classes revealed highly selective patterns of pulmonary peroxidation after inhalation exposure of mice to single-walled carbon nanotubes. No oxidized molecular species were found in two most abundant phospholipid classes – phosphatidylcholine and phosphatidylethanolamine. Peroxidation products were identified in three relatively minor classes of anionic phospholipids, cardiolipin, phosphatidylserine and phosphatidylinositol whereby oxygenation of polyunsaturated fatty acid residues also showed unusual substrate specificity. This non-random peroxidation coincided with the accumulation of apoptotic cells in the lung. A similar selective phospholipid peroxidation profile was detected upon incubation of a mixture of total lung lipids with H2O2/cytochrome c known to catalyze cardiolipin and phosphatidylserine peroxidation in apoptotic cells. The characterized specific phospholipid peroxidation signaling pathways indicate new approaches to the development of mitochondria targeted regulators of cardiolipin peroxidation to protect against deleterious effects of pro-apoptotic effects of single-walled carbon nanotubes in the lung. PMID:21800898

  16. Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery

    NASA Astrophysics Data System (ADS)

    Smith, Bryan Ronain; Ghosn, Eliver Eid Bou; Rallapalli, Harikrishna; Prescher, Jennifer A.; Larson, Timothy; Herzenberg, Leonore A.; Gambhir, Sanjiv Sam

    2014-06-01

    In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using `bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6Chi monocytes (almost 100% uptake in Ly-6Chi monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.

  17. Global phospholipidomics analysis reveals selective pulmonary peroxidation profiles upon inhalation of single-walled carbon nanotubes.

    PubMed

    Tyurina, Yulia Y; Kisin, Elena R; Murray, Ashley; Tyurin, Vladimir A; Kapralova, Valentina I; Sparvero, Louis J; Amoscato, Andrew A; Samhan-Arias, Alejandro K; Swedin, Linda; Lahesmaa, Riitta; Fadeel, Bengt; Shvedova, Anna A; Kagan, Valerian E

    2011-09-27

    It is commonly believed that nanomaterials cause nonspecific oxidative damage. Our mass spectrometry-based oxidative lipidomics analysis of all major phospholipid classes revealed highly selective patterns of pulmonary peroxidation after inhalation exposure of mice to single-walled carbon nanotubes. No oxidized molecular species were found in the two most abundant phospholipid classes: phosphatidylcholine and phosphatidylethanolamine. Peroxidation products were identified in three relatively minor classes of anionic phospholipids, cardiolipin, phosphatidylserine, and phosphatidylinositol, whereby oxygenation of polyunsaturated fatty acid residues also showed unusual substrate specificity. This nonrandom peroxidation coincided with the accumulation of apoptotic cells in the lung. A similar selective phospholipid peroxidation profile was detected upon incubation of a mixture of total lung lipids with H(2)O(2)/cytochrome c known to catalyze cardiolipin and phosphatidylserine peroxidation in apoptotic cells. The characterized specific phospholipid peroxidation signaling pathways indicate new approaches to the development of mitochondria-targeted regulators of cardiolipin peroxidation to protect against deleterious effects of pro-apoptotic effects of single-walled carbon nanotubes in the lung. PMID:21800898

  18. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes.

    PubMed

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M; Hároz, Erik H; Doorn, Stephen K; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M; Adams, W Wade; Hauge, Robert H; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm(2)) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 10(6) nanotubes in a cross-sectional area of 1 μm(2). The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios. PMID:27043199

  19. Wafer-scale monodomain films of spontaneously aligned single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    He, Xiaowei; Gao, Weilu; Xie, Lijuan; Li, Bo; Zhang, Qi; Lei, Sidong; Robinson, John M.; Hároz, Erik H.; Doorn, Stephen K.; Wang, Weipeng; Vajtai, Robert; Ajayan, Pulickel M.; Adams, W. Wade; Hauge, Robert H.; Kono, Junichiro

    2016-07-01

    The one-dimensional character of electrons, phonons and excitons in individual single-walled carbon nanotubes leads to extremely anisotropic electronic, thermal and optical properties. However, despite significant efforts to develop ways to produce large-scale architectures of aligned nanotubes, macroscopic manifestations of such properties remain limited. Here, we show that large (>cm2) monodomain films of aligned single-walled carbon nanotubes can be prepared using slow vacuum filtration. The produced films are globally aligned within ±1.5° (a nematic order parameter of ∼1) and are highly packed, containing 1 × 106 nanotubes in a cross-sectional area of 1 μm2. The method works for nanotubes synthesized by various methods, and film thickness is controllable from a few nanometres to ∼100 nm. We use the approach to create ideal polarizers in the terahertz frequency range and, by combining the method with recently developed sorting techniques, highly aligned and chirality-enriched nanotube thin-film devices. Semiconductor-enriched devices exhibit polarized light emission and polarization-dependent photocurrent, as well as anisotropic conductivities and transistor action with high on/off ratios.

  20. Composite of single walled carbon nanotube and sulfosalicylic acid doped polyaniline: a thermoelectric material

    NASA Astrophysics Data System (ADS)

    Jana Chatterjee, Mukulika; Banerjee, Dipali; Chatterjee, Krishanu

    2016-08-01

    Nanocomposites containing single walled carbon nanotubes (SWCNTs) and highly ordered polyaniline (PANI) have been synthesized employing an in situ polymerization using different weight percentages of single-walled carbon nanotube (SWCNT) as template and aniline as a reactant. The composites show homogeneously dispersed SWCNTs which are uniformly coated with PANI through a strong interface interaction. Structural characterization shows that the PANI cultivated along the surface of the SWCNTs in an ordered manner during the SWCNT-directed polymerization process. Measurements at room temperature displayed a significant enhancement in both the electrical conductivity and thermoelectric power which could be attributed to the more ordered chain structures of the PANI on SWCNT. As a result, the power factor of the composite is improved which increases with temperature. At the same time, the measured value of thermal conductivity at room temperature being lowest among the reported values, has resulted in best ZT at room temperature. The lowest value of thermal conductivity is attributed to the large phonon scattering due to the introduction of nanointerfaces.

  1. Functionalization of single-walled carbon nanotubes regulates their effect on hemostasis

    NASA Astrophysics Data System (ADS)

    Sokolov, A. V.; Aseychev, A. V.; Kostevich, V. A.; Gusev, A. A.; Gusev, S. A.; Vlasova, I. I.

    2011-04-01

    Applications of single-walled carbon nanotubes (SWNTs) in medical field imply the use of drug-coupled carbon nanotubes as well as carbon nanotubes functionalized with different chemical groups that change nanotube surface properties and interactions between nanotubes and cells. Covalent attachment of polyethylene glycol (PEG) to carboxylated single-walled carbon nanotubes (c-SWNT) is known to prevent the nanotubes from interaction with macrophages. Here we characterized nanotube's ability to stimulate coagulation processes in platelet-poor plasma (PPP), and evaluated the effect of SWNTs on platelet aggregation in platelet-rich plasma (PRP). Our study showed that PEG-SWNT did not affect the rate of clotting in PPP, while c-SWNT shortened the clot formation time five times compared to the control PPP. Since c-SWNT failed to accelerate coagulation in plasma lacking coagulation factor XI, it may be suggested that c-SWNT affects the contact activation pathway. In PRP, platelets responded to both SWNT types with irreversible aggregation, as evidenced by changes in the aggregate mean radius. However, the rate of aggregation induced by c-SWNT was two times higher than it was with PEG-SWNT. Cytological analysis also showed that c-SWNT was two times more efficient when compared to PEG-SWNT in aggregating platelets in PRP. Taken together, our results show that functionalization of nanoparticles can diminish their negative influence on blood cells. As seen from our data, modification of c-SWNT with PEG, when only a one percent of carbon atoms is bound to polymer (70 wt %), decreased the nanotube-induced coagulation in PRP and repelled the accelerating effect on the coagulation in PPP. Thus, when functionalized SWNTs are used for administration into bloodstream of laboratory animals, their possible pro-coagulant and pro-aggregating properties must be taken into account.

  2. Development of novel single-wall carbon nanotube epoxy composite ply actuators

    NASA Astrophysics Data System (ADS)

    Yun, Yeo-Heung; Shanov, Vesselin; Schulz, Mark J.; Narasimhadevara, Suhasini; Subramaniam, Srinivas; Hurd, Douglas; Boerio, F. J.

    2005-12-01

    This paper describes a carbon nanotube epoxy ply material that has electrochemical actuation properties. The material was formed by dispersing single-wall carbon nanotubes in a solvent and then solution casting a thin paper using a mold and vacuum oven. In order to take advantage of the high elastic modulus of carbon nanotubes for actuation, epoxy as a chemically inert polymer is considered. An epoxy layer was cast on the surface of the nanotube paper to make a two-layer ply. A wet electrochemical actuator was formed by placing the nanotube epoxy ply in a 2 M NaCl electrolyte solution. Electrochemical impedance spectroscopy and cyclic voltammetry were carried out to characterize the electrochemical properties of the actuator. The voltage-current relationship and power to drive the actuator material were also determined. Compared to previous single-wall carbon nanotube buckypaper tape actuators, which had poor adhesion between the nanotubes and tape, and other nanotube-thermal plastic polymer actuators, which could not provide high strength, the epoxy based actuator has a higher elastic modulus and strength, which will be useful for future structural applications. This demonstrates that a polymer layer can reinforce nanotube paper, which is an important step in building a new structural material that actuates. Further work is under way to develop a solid electrolyte to allow dry actuation. Finally, these actuator plies will be laminated to build a carbon nanocomposite material. This smart structural material will have potential applications that range from use in robotic surgical tools to use as structures that change shape.

  3. Optical and electrical studies of single walled carbon nanotubes for infrared sensing and photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Omari, Mones A.

    Carbon nanotubes are emerging as highly promising opto-electro-mechanical device components essential for the development of a variety of hybrid opto-electronic, electro-mechanical and bio-medical technologies on the nanoscale and have been a subject of continued research. In particular, single-walled carbon nanotubes are predicted to exhibit strong light absorption induced by photon-assisted electronic transitions, free carrier and plasmonic-based absorption. Single-walled carbon nanotubes have been confirmed to exhibit a strong photoconduction response in the infrared range, which can provide many new opportunities in engineering nano-photovoltaic and optoelectronic devices. At the same time, the use of strong chemical reagents has been long considered as one of the key processing steps for the separation and purification of single-walled carbon nanotube post-synthesis. In this work, optically-induced voltage in carbon nanotube bundles and thin-films configured as two-terminal resistive elements and operating as junctionless photo-cells in the infrared range as well as the time-dependent wet-processing of HiPCo nanotubes in phosphoric acid and its effect on the structural, transport, infrared light absorption, and photoconduction characteristics were studied. As the photo-voltage generated is found to appear only for asymmetric and off-contact illuminations, the effect is explained based on a photo-generated heat flow model. The engineered cell prototypes were found to yield electrical powers of ˜ 30 pW while demonstrating improved conversion efficiency under high-flux illumination. The cell is also shown to act as an uncooled infrared sensor, with its dark-to-photocurrent ratio improving as temperature increases. The wet-processing of HiPCo nanotubes was done for a nominal time intervals of 1, 2 and 3 hours. The treatment was found to be a two-step process that initially results in the removal and partial replacement of most pre-existing C-O, O-H and CHx groups

  4. Multi-Fractal Hierarchy of Single-Walled Carbon Nanotube Hydrophobic Coatings

    PubMed Central

    De Nicola, Francesco; Castrucci, Paola; Scarselli, Manuela; Nanni, Francesca; Cacciotti, Ilaria; De Crescenzi, Maurizio

    2015-01-01

    A hierarchical structure is an assembly with a multi-scale morphology and with a large and accessible surface area. Recent advances in nanomaterial science have made increasingly possible the design of hierarchical surfaces with specific and tunable properties. Here, we report the fractal analysis of hierarchical single-walled carbon nanotube (SWCNT) films realized by a simple, rapid, reproducible, and inexpensive filtration process from an aqueous dispersion, then deposited by drytransfer printing method on several substrates, at room temperature. Furthermore, by varying the thickness of carbon nanotube random networks, it is possible tailoring their wettability due to capillary phenomena in the porous films. Moreover, in order to describe the wetting properties of such surfaces, we introduce a two-dimensional extension of the Wenzel-Cassie-Baxter theory. The hierarchical surface roughness of SWCNT coatings coupled with their exceptional and tunable optical and electrical properties provide an ideal hydrophobic composite surface for a new class of optoelectronic and nanofluidic devices. PMID:25716718

  5. A parametric study of single-wall carbon nanotube growth by laser ablation

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram; Holmes, William A.; Nikolaev, Pavel; Hadjiev, Victor G.; Scott, Carl D.

    2004-01-01

    Results of a parametric study of carbon nanotube production by the double-pulse laser oven process are presented. The effect of various operating parameters on the production of single-wall carbon nanotubes (SWCNTs) is estimated by characterizing the nanotube material using analytical techniques, including scanning electron microscopy, transmission electron microscopy, thermo gravimetric analysis and Raman spectroscopy. The study included changing the sequence of the laser pulses, laser energy, pulse separation, type of buffer gas used, operating pressure, flow rate, inner tube diameter, as well as its material, and oven temperature. It was found that the material quality and quantity improve with deviation from normal operation parameters such as laser energy density higher than 1.5 J/cm2, pressure lower than 67 kPa, and flow rates higher than 100 sccm. Use of helium produced mainly small diameter tubes and a lower yield. The diameter of SWCNTs decreases with decreasing oven temperature and lower flow rates.

  6. Grafting of Chitosan and Chitosantrimethoxylsilylpropyl Methacrylate on Single Walled Carbon Nanotubes-Synthesis and Characterization

    PubMed Central

    Carson, Laura; Kelly-Brown, Cordella; Stewart, Melisa; Oki, Aderemi; Regisford, Gloria; Stone, Julia; Traisawatwong, Pasakorn; Durand-Rougely, Clarissa; Luo, Zhiping

    2011-01-01

    Acid functionalized single walled carbon nanotubes (CNTs) were grafted to chitosan by first reacting the oxidized CNTs with thionyl chloride to form acyl-chlorinated CNTs. This product was subsequently dispersed in chitosan and covalently grafted to form CNT-chitosan. CNT-chitosan was further grafted onto 3-trimethoxysilylpropyl methacrylate by free radical polymerization conditions, to yield CNT-g-chitosan-g-3-trimethoxysilylpropyl methacrylate (TMSPM), hereafter referred to as CNT-chitosan-3-TMSPM. These composites were characterized by Fourier Transform Infrared Resonance Spectroscopy (FTIR), carbon-13 nuclear magnetic resonance (13C NMR), Thermogravimetric Analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composite showed improved thermal stability and could be of great potential use in bone tissue engineering. PMID:21765959

  7. Zipping, entanglement, and the elastic modulus of aligned single-walled carbon nanotube films.

    PubMed

    Won, Yoonjin; Gao, Yuan; Panzer, Matthew A; Xiang, Rong; Maruyama, Shigeo; Kenny, Thomas W; Cai, Wei; Goodson, Kenneth E

    2013-12-17

    Reliably routing heat to and from conversion materials is a daunting challenge for a variety of innovative energy technologies--from thermal solar to automotive waste heat recovery systems--whose efficiencies degrade due to massive thermomechanical stresses at interfaces. This problem may soon be addressed by adhesives based on vertically aligned carbon nanotubes, which promise the revolutionary combination of high through-plane thermal conductivity and vanishing in-plane mechanical stiffness. Here, we report the data for the in-plane modulus of aligned single-walled carbon nanotube films using a microfabricated resonator method. Molecular simulations and electron microscopy identify the nanoscale mechanisms responsible for this property. The zipping and unzipping of adjacent nanotubes and the degree of alignment and entanglement are shown to govern the spatially varying local modulus, thereby providing the route to engineered materials with outstanding combinations of mechanical and thermal properties. PMID:24309375

  8. Hybrid Graphene and Single-Walled Carbon Nanotube Films for Enhanced Phase-Change Heat Transfer.

    PubMed

    Seo, Han; Yun, Hyung Duk; Kwon, Soon-Yong; Bang, In Cheol

    2016-02-10

    Nucleate boiling is an effective heat transfer method in power generation systems and cooling devices. In this letter, hybrid graphene/single-walled carbon nanotube (SWCNT), graphene, and SWCNT films deposited on indium tin oxide (ITO) surfaces were fabricated to investigate the enhancement of nucleate boiling phenomena described by the critical heat flux and heat transfer coefficient. The graphene films were grown on Cu foils and transferred to ITO surfaces. Furthermore, SWCNTs were deposited on the graphene layer to fabricate hybrid graphene/SWCNT films. We determined that the hybrid graphene/SWCNT film deposited on an ITO surface is the most effective heat transfer surface in pool boiling because of the interconnected network of carbon structures. PMID:26731547

  9. Magnetic-field-induced diameter-selective synthesis of single-walled carbon nanotubes.

    PubMed

    Su, Yanjie; Zhang, Yaozhong; Wei, Hao; Zhang, Liling; Zhao, Jiang; Yang, Zhi; Zhang, Yafei

    2012-03-01

    We report a facile and scalable approach to synthesize single-walled carbon nanotubes (SWNTs) with selected diameter distribution by applying a magnetic field perpendicular to the electric field in the arc plasma region. It is found that this magnetic field-induced diameter-selectivity strategy enables the control of the SWNTs with different diameter distributions in different regions, and the diameter-selective efficiency could be enhanced by modifying the direction of magnetic field. Our results indicate that the motions of the catalysts with different particle sizes, positive carbon ions and electrons are significantly influenced by the magnetic field and electromagnetic force, resulting in the different nucleation and growth processes of SWNTs due to the collective interactions between the magnetic field and arc plasma. This approach would enable a viable route towards the synthesis of SWNTs with desired diameter through the tuning of arc parameters in the arc discharge process. PMID:22301844

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

    PubMed

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

    2006-05-01

    Classical molecular dynamics simulations are carried out to analyze the physical state of the catalyst, and the growth of single-wall carbon nanotubes under typical temperature and pressure conditions of their experimental synthesis, emphasizing the role of the catalyst/substrate interactions. It is found that a strong cluster/substrate interaction increases the cluster melting point, modifying the initial stages of carbon dissolution and precipitation on the cluster surface. Experiments performed on model Co-Mo catalysts clearly illustrate the existence of an initial period where the catalyst is formed and no nanotube growth is observed. To quantify the nature of the Co-Mo2C interaction, quantum density functional theory is applied to characterize structural and energetic features of small Co clusters deposited on a (001) Mo2C surface, revealing a strong attachment of Co-clusters to the Mo2C surface, which may increase the melting point of the cluster and prevent cluster sintering. PMID:16792351

  11. Fabrication and performance of contamination free individual single-walled carbon nanotube optical devices.

    PubMed

    Zhou, Yuxiu; Cheng, Rong; Liu, Jianqiang; Li, Tie

    2014-06-01

    Contamination free individual single-walled carbon nanotube (SWCNT) optical devices are fabricated using a hybrid method in the purpose of increase sensitivity as well as further understanding the sensing mechanism. The devices were tested in vacuum to avoid contamination. Three typical devices are discussed comparatively. Under infrared lamp illumination, photovoltaic and photoconductive properties are revealed in device A and B respectively, while device C shows no detectable signal. The photoresponse of device B reaches 108% at 78 K, much larger than that of horizontally aligned or network carbon nanotube devices, indicating priority of the individual nanotube device structure. Interestingly, the temperature characteristics of device A and B are just the opposite. The individual SWCNT devices hold promise in high performance and low cost optical sensors as well as nano-scale solar cells. PMID:24738376

  12. Ferromagnetism/antiferromagnetism transition between semihydrogenated and fully-aminated single-wall carbon nanotubes.

    PubMed

    Deng, Qingming; Zhao, Lina; Luo, Youhua; Zhang, Meng; Jing, Long; Zhao, Yuliang

    2011-09-01

    We theoretically studied the ferromagnetism/antiferromagnetism (FM/AFM) transition between single-wall carbon nanotubes (SWCNTs) induced by chemical modifications of semihydrogenation (SH-) and full-amination (NH(2)-). We found that armchairs with large diameters of SH-CNTs (n > 3) possess FM functions with intense magnetic moments, while armchair NH(2)-CNTs (n = 4, 6, 8) are antiferromagnetic semiconductors. The FM/AFM transition is mainly dominated by different chemical modifications and sizes of SWCNTs whose distance between carbon atoms of unpaired electrons can regulate the intensity of p-p spin interactions. Moreover, the zigzag SH-CNTs and NH(2)-CNTs are NM semiconductors. Thus, the electronic and magnetic properties of the SH- or NH(2)-CNTs can be precisely modulated by controlling the hydrogenation or amination on the different types and diameters of CNTs, which provides a new and also simple process for magnetism optimization design in SWCNTs. PMID:21804988

  13. Ferromagnetism/antiferromagnetism transition between semihydrogenated and fully-aminated single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Deng, Qingming; Zhao, Lina; Luo, Youhua; Zhang, Meng; Jing, Long; Zhao, Yuliang

    2011-09-01

    We theoretically studied the ferromagnetism/antiferromagnetism (FM/AFM) transition between single-wall carbon nanotubes (SWCNTs) induced by chemical modifications of semihydrogenation (SH-) and full-amination (NH2-). We found that armchairs with large diameters of SH-CNTs (n > 3) possess FM functions with intense magnetic moments, while armchair NH2-CNTs (n = 4, 6, 8) are antiferromagnetic semiconductors. The FM/AFM transition is mainly dominated by different chemical modifications and sizes of SWCNTs whose distance between carbon atoms of unpaired electrons can regulate the intensity of p-p spin interactions. Moreover, the zigzag SH-CNTs and NH2-CNTs are NM semiconductors. Thus, the electronic and magnetic properties of the SH- or NH2-CNTs can be precisely modulated by controlling the hydrogenation or amination on the different types and diameters of CNTs, which provides a new and also simple process for magnetism optimization design in SWCNTs.

  14. Swift heavy ion induced modifications of single walled carbon nanotube thin films

    NASA Astrophysics Data System (ADS)

    Vishalli; Raina, K. K.; Avasthi, D. K.; Srivastava, Alok; Dharamvir, Keya

    2016-04-01

    Thin films of single walled carbon nanotubes (SWCNTs) were prepared by Langmuir-Blodgett method and irradiated with swift heavy ions, carbon and nickel each of energy 60 MeV. The ion beams have different electronic energy loss (Se) values and the samples were exposed to various irradiation doses. The irradiated films were characterized using Raman and optical absorption spectroscopy. Raman spectroscopy results indicate the competing processes of defect creation and healing (annealing) of SWCNTs at lower fluences, while at higher fluences defect creation or damage dominates. In UV-Vis-NIR spectroscopy we find that there is decrease in the intensity of characteristic peaks with every increasing fluence, indicating decrease in the optically active states with irradiation.

  15. Torsional characteristics of graphene nanoribbons encapsulated in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fang, Te-Hua; Chang, Win-Jin; Feng, Yu-Lun; Lu, Deng-Maw

    2016-09-01

    Molecular dynamics (MD) simulations were performed to study the torsional characteristics of a graphene nanoribbon encapsulated in a single-walled carbon nanotube (GNR@SWCNT) with different chiralities at different temperatures. Based on the simulations, the relationship between the shear stress and the twist angle was obtained. The maximum shear stress increases with an increase in chirality. However, the corresponding twist angle decreases with increasing chirality. GNR@SWCNT withstands a smaller twist angle compared with a single SWCNT. In addition, the interaction force between the GNR and the SWCNT increases with increasing temperature. GNR@SWCNT at an elevated temperature is easier to break during torsion with a lower twist angle. The results are valuable for the design of nanocomposites composed of carbon nanotubes and graphene materials.

  16. The effect of fibronectin on structural and biological properties of single walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Mottaghitalab, Fatemeh; Farokhi, Mehdi; Atyabi, Fatemeh; Omidvar, Ramin; Shokrgozar, Mohammad Ali; Sadeghizadeh, Majid

    2015-06-01

    Despite the attractive properties of carbon nanotubes (CNTs), cytoxicity and hydrophobicity are two main considerable features which limit their application in biomedical fields. It was well established that treating CNTs with extracellular matrix components could reduce these unfavourable characteristics. In an attempt to address these issues, fibronectin (FN) with different concentrations was loaded on single walled carbon nanotubes (SWCNTs) substrate. Scanning electron microscope, atomic force microscopy (AFM), contact angles and X-ray photoelectron spectroscopy (XPS) were preformed in order to characterize FN loaded SWCNTs substrates. According to XPS and AFM results, FN could interact with SWCNTs and for this, the hydrophilicity of SWCNTs was improved. Additionally, SWCNT modified with FN showed less cytotoxicity compared with neat SWCNT. Finally, FN was shown to act as an interesting extracellular component for enhancing the biological properties of SWCNT.

  17. Magnetic Property Measurements on Single Wall Carbon Nanotube-Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Sun, Keun J.; Wincheski, Russell A.; Park, Cheol

    2008-01-01

    Temperature and magnetic field dependent magnetization measurements were performed on polyimide nanocomposite samples, synthesized with various weight percentages of single wall carbon nanotubes. It was found that the magnetization of the composite, normalized to the mass of nanotube material in the sample, decreased with increasing weight percentage of nanotubes. It is possible that the interfacial coupling between the carbon nanotube (CNT) fillers and the polyimide matrix promotes the diamagnetic response from CNTs and reduces the total magnetization of the composite. The coercivity of the samples, believed to originate from the residual magnetic catalyst particles, was enhanced and had a stronger temperature dependence as a result of the composite synthesis. These changes in magnetic properties can form the basis of a new approach to investigate the interfacial properties in the CNT nanocomposites through magnetic property measurements.

  18. DNA Linked To Single Wall Carbon Nanotubes: Covalent Versus Non-Covalent Approach

    NASA Astrophysics Data System (ADS)

    Chung, C.-L.; Nguyen, K.; Lyonnais, S.; Streiff, S.; Campidelli, S.; Goux-Capes, L.; Bourgoin, J.-P.; Filoramo, A.

    2008-10-01

    Nanometer-scale structures represent a novel and intriguing field, where scientists and engineers manipulate materials at the atomic and molecular scale levels to produce innovative materials. Carbon nanotubes constitute a relatively new class of materials exhibiting exceptional mechanical and electronic properties and were found to be promising candidates for molecular electronics, sensing or biomedical applications. Considering the bottom-up strategy in nanotechnology, the combination of the recognition properties of DNA with the electronic properties of single walled carbon nanotubes (SWNTs) seems to be a promising approach for the future of electronics. With the aim to assemble DNA with SWNTs, two complementary strategies have been envisioned: the covalent linkage of DNA on carboxylic groups of SWNTs under classical coupling condition and the non-covalent approach based on biotin-streptavidin molecular recognition properties. Here, we present and compare the results that we obtained with these two different methods; we want to objectively show the advantages and disadvantages of each approach.

  19. Covalent sidewall functionalization of single-walled carbon nanotubes: a photoreduction approach.

    PubMed

    Wei, Liangming; Zhang, Yafei

    2007-12-12

    Covalent sidewall functionalization of single-walled carbon nanotubes (SWNTs) via photoreduction of aromatic ketones by alcohols is reported for the first time. Irradiation of benzophenone, benzhydrol and SWNTs in benzene resulted in covalent attachment of benzhydrol to the sidewalls of the SWNTs. A variety of tools were used to characterize the functionalized SWNTs. Raman scattering, UV-visible and near-IR spectroscopy confirm the covalent nature of the sidewall functionalization. Attenuated total reflection (ATR) FTIR and NMR provided evidence for attachment of benzhydrol onto the sidewalls of nanotubes. Thermogravimetric analysis (TGA) showed that the degree of functionalization was about one benzhydrol in 52 sidewall carbons. A long-chain hydrocarbon marker (n-C(18)H(35)) was also grafted onto the functional groups by esterification reaction for high-resolution TEM (HRTEM) visualization. PMID:20442484

  20. Thermal expansion of single-walled carbon nanotube (SWNT) bundles: X-ray diffraction studies

    NASA Astrophysics Data System (ADS)

    Maniwa, Yutaka; Fujiwara, Ryuji; Kira, Hiroshi; Tou, Hideki; Kataura, Hiromichi; Suzuki, Shinzo; Achiba, Yohji; Nishibori, Eiji; Takata, Masaki; Sakata, Makoto; Fujiwara, Akihiko; Suematsu, Hiroyoshi

    2001-12-01

    Thermal expansion coefficient in single-walled carbon nanotube bundles was determined as (-0.15+/-0.20)×10-5 (1/K) for the tube diameter and (0.75+/-0.25)×10-5 (1/K) for the triangular lattice constant by means of x-ray scattering between 300 K to 950 K. The value for the intertube gap was (4.2+/-1.4)×10-5 (1/K), which is larger than 2.6×10-5 (1/K) for the c-axis thermal expansion in graphite. The results reveal the presence of a remarkably larger lattice anharmonicity in nanotube bundles than that of graphite. The small value for the tube diameter is consistent with the seamless tube structure formed by a strong covalent bond between carbon atoms comparable to that in graphite.

  1. Enzymatic formation of carbohydrate rings catalyzed by single-walled carbon nanotubes.

    PubMed

    Hyun, Moon Seop; Park, Jong Pil; Seo, Dongkyun; Chang, Sung-Jin; Lee, Seok Jae; Lee, Sang Yup; Kwak, Kyungwon; Park, Tae Jung

    2016-05-01

    Macrocyclic carbohydrate rings were formed via enzymatic reactions around single-walled carbon nanotubes (SWNTs) as a catalyst. Cyclodextrin glucanotransferase, starch substrate and SWNTs were reacted in buffer solution to yield cyclodextrin (CD) rings wrapped around individual SWNTs. Atomic force microscopy showed the resulting complexes to be rings of 12-50 nm in diameter, which were highly soluble and dispersed in aqueous solution. They were further characterized by Raman and Fourier transform infrared spectroscopy and molecular simulation using density functional theory calculation. In the absence of SWNT, hydrogen bonding between glucose units determines the structure of maltose (the precursor of CD) and produces the curvature along the glucose chain. Wrapping SWNT along the short axis was preferred with curvature in the presence of SWNTs and with the hydrophobic interactions between the SWNTs and CD molecules. This synthetic approach may be useful for the functionalization of carbon nanotubes for development of nanostructures. PMID:26946491

  2. Photon antibunching in single-walled carbon nanotubes at telecommunication wavelengths and room temperature

    SciTech Connect

    Endo, Takumi Ishi-Hayase, Junko; Maki, Hideyuki

    2015-03-16

    We investigated the photoluminescence of individual air-suspended single-walled carbon nanotubes (SWNTs) from 6 to 300 K. Time-resolved and antibunching measurements over the telecommunication wavelength range were performed using a superconducting single-photon detector. We detected moderate temperature independent antibunching behavior over the whole temperature range studied. To investigate the exciton dynamics, which is responsible for the antibunching behavior, we measured excitation-power and temperature dependence of the photoluminescence spectra and lifetime decay curves. These measurements suggested an exciton confinement effect that is likely caused by high-dielectric amorphous carbon surrounding the SWNTs. These results indicate that SWNTs are good candidates for light sources in quantum communication technologies operating in the telecommunication wavelength range and at room temperature.

  3. Growth dynamics of inner tubes inside cobaltocene-filled single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kharlamova, M. V.; Kramberger, Christian; Saito, Takeshi; Shiozawa, Hidetsugu; Pichler, Thomas

    2016-08-01

    We have synthesized cobaltocene-filled 1.7-nm-mean diameter single-walled carbon nanotubes (SWCNTs) and transformed them into double-walled carbon nanotubes by annealing at temperatures between 500 and 1000 °C for 2 h in vacuum. We analyze the temperature-dependent inner tube growth inside the filled SWCNTs by Raman spectroscopy. The changes in intensity of the Raman peaks of inner tubes with the diameters ranging from 0.832 to 1.321 nm with increasing annealing temperature are traced. It is revealed that the growth temperatures of larger diameter inner tubes are higher than the ones of smaller diameter tubes. A decrease in the diameter of the inner tubes by ~0.4 nm leads to a decrease in the growth temperature by ~200 °C.

  4. Interfacial Surfactant Ordering in Thin Films of SDS-Encapsulated Single-Walled Carbon Nanotubes.

    PubMed

    Das, Sushanta K; Sengupta, Sanghamitra; Velarde, Luis

    2016-01-21

    The molecular self-assembly of surfactants on the surface of single-walled carbon nanotubes (SWCNT) is currently a common strategy for the tuning of nanotube properties and the stabilization of carbon nanotube dispersions. Here, we report direct measurements of the degree of interfacial ordering for sodium dodecyl sulfate (SDS) surfactants adsorbed on colloidal, single-chirality enriched, SWCNTs within a solid film and investigate the dependence of surface alkyl chain order on the surfactant concentration in the precursor solution. The degree of order for the SWCNT-bound SDS molecules, is probed by vibrational sum frequency generation (VSFG) spectroscopy. We find concrete evidence for the presence of highly ordered surface structures at sufficiently high SDS concentrations, attributed here to cylindrical-like micelle assemblies with the SWCNT at the core. As the SDS concentration decreases, the interfacial order is found to decrease as well, generating a more disordered or random adsorption of surfactants on the nanotube surfaces. PMID:26730991

  5. Energy Band Gap Study of Semiconducting Single Walled Carbon Nanotube Bundle

    NASA Technical Reports Server (NTRS)

    Elkadi, Asmaa; Decrossas, Emmanuel; El-Ghazaly, Samir

    2013-01-01

    The electronic properties of multiple semiconducting single walled carbon nanotubes (s-SWCNTs) considering various distribution inside a bundle are studied. The model derived from the proposed analytical potential function of electron density for na individual s-SWCNT is general and can be easily applied to multiple nanotubes. This work demonstrates that regardless the number of carbon nanotubes, the strong coupling occurring between the closet neighbors reduces the energy band gap of the bundle by 10%. As expected, the coupling is strongly dependent on the distance separating the s-SWCNTs. In addition, based on the developed model, it is proposed to enhance this coupling effect by applying an electric field across the bundle to significantly reduce the energy band gap of the bundle by 20%.

  6. Energy Band Gap Study of Semiconducting Single Walled Carbon Nanotube Bundle

    NASA Technical Reports Server (NTRS)

    Elkadi, Asmaa; Decrossas, Emmanuel; El-Ghazaly, Samir

    2013-01-01

    The electronic properties of multiple semiconducting single walled carbon nanotubes (s-SWCNTs) considering various distribution inside a bundle are studied. The model derived from the proposed analytical potential function of the electron density for an individual s-SWCNT is general and can be easily applied to multiple nanotubes. This work demonstrates that regardless the number of carbon nanotubes, the strong coupling occurring between the closest neighbours reduces the energy band gap of the bundle by 10%. As expected, the coupling is strongly dependent on the distance separating the s-SWCNTs. In addition, based on the developed model, it is proposed to enhance this coupling effect by applying an electric field across the bundle to significantly reduce the energy band gap of the bundle by 20%.

  7. Adsorption equilibrium of organic vapors on single-walled carbon nanotubes

    USGS Publications Warehouse

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

    2005-01-01

    Gravimetric techniques were employed to determine the adsorption capacities of commercially available purified electric arc and HiPco single-walled carbon nanotubes (SWNTs) for organic compounds (toluene, methyl ethyl ketone (MEK), hexane and cyclohexane) at relative pressures, p/p0, ranging from 1 ?? 10-4 to 0.95 and at isothermal conditions of 25, 37 and 50 ??C. The isotherms displayed both type I and type II characteristics. Adsorption isotherm modeling showed that SWNTs are heterogeneous adsorbents, and the Freundlich equation best describes the interaction between organic molecules and SWNTs. The heats of adsorption were 1-4 times the heats of vaporization, which is typical for physical adsorption of organic vapors on porous carbons. ?? 2005 Elsevier Ltd. All rights reserved.

  8. Zipping, entanglement, and the elastic modulus of aligned single-walled carbon nanotube films

    PubMed Central

    Won, Yoonjin; Gao, Yuan; Panzer, Matthew A.; Xiang, Rong; Maruyama, Shigeo; Kenny, Thomas W.; Cai, Wei; Goodson, Kenneth E.

    2013-01-01

    Reliably routing heat to and from conversion materials is a daunting challenge for a variety of innovative energy technologies––from thermal solar to automotive waste heat recovery systems––whose efficiencies degrade due to massive thermomechanical stresses at interfaces. This problem may soon be addressed by adhesives based on vertically aligned carbon nanotubes, which promise the revolutionary combination of high through-plane thermal conductivity and vanishing in-plane mechanical stiffness. Here, we report the data for the in-plane modulus of aligned single-walled carbon nanotube films using a microfabricated resonator method. Molecular simulations and electron microscopy identify the nanoscale mechanisms responsible for this property. The zipping and unzipping of adjacent nanotubes and the degree of alignment and entanglement are shown to govern the spatially varying local modulus, thereby providing the route to engineered materials with outstanding combinations of mechanical and thermal properties. PMID:24309375

  9. Growth and Characterization of Isolated Single Wall Carbon Nanotubes using Liquid Precursors

    NASA Astrophysics Data System (ADS)

    Choi, Young Chul; Parker, Allen; Kesker, Gayatri; Luo, J.; Rao, A. M.

    2004-03-01

    Isolated single wall carbon nanotubes (SWNTs) were prepared on quartz and oxidized silicon substrates using chemical vapor deposition (CVD) in which a liquid precursor, such as xylene, was used as the carbon source. The density of isolated SWNTs was controlled by adjusting the concentration of iron (III) nitrate nonahydrate/2-propanol solution which provided the Fe seed catalyst particles. Micro-Raman measurements using the 785 nm excitation showed tangential bands around 1590 cm-1. The radial breathing mode (RBM) peaks ranged from 150 - 240 cm-1 and the estimated tube diameters are in good agreement with those obtained from atomic force microscope (AFM) images. Our synthesis technique facilitates controlled doping of isolated SWNTs with nitrogen and is achieved by mixing acetonitrile with xylene. Isolated nitrogen doped SWNTs are useful in making stable TUBEFETs.

  10. In vivo MRI of single-wall carbon nanohorns through magnetite nanoparticle attachment

    NASA Astrophysics Data System (ADS)

    Miyawaki, Jin; Yudasaka, Masako; Imai, Hideto; Yorimitsu, Hideki; Isobe, Hiroyuki; Nakamura, Eiichi; Iijima, Sumio

    2006-03-01

    Superparamagnetic magnetite (SPM) is used as a contrast agent in magnetic resonance imaging (MRI). Thus, the SPM-attachment to carbon nanotubes (CNTs) will enable to visualize motional behaviors of CNTs in the living body through MRI. We found that the strong attachment of the SPM nanoparticles (ca. 6 nm size) to one type of CNTs, single-wall carbon nanohorns (SWNHs), could be achieved through a deposition of iron acetate clusters on SWNHs in ethanol at room temperature, followed by heat-treatment in Ar. In vivo MRI visualized that the SWNHs attached with the SPM nanoparticles accumulated in several organs of mice when injected into mice via tail veins. This simple method for the SPM-attaching on CNTs would facilitate the toxicity assessment of CNTs and the applications of CNTs in bioscience and biotechnology.

  11. Separation of Single-Walled Carbon Nanotubes with DEP-FFF

    NASA Technical Reports Server (NTRS)

    Schmidt, Howard K.; Peng, Haiqing; Alvarez, Noe; Mendes, Manuel; Pasquali, Matteo

    2011-01-01

    A process using a modified dielectrophoresis device separates single-walled carbon nanotubes (SWNTs) according to their polarizability in electric fields. This depends on the size and dielectric constant of individual nanotubes and easily separates metallic from semiconducting nanotubes. Separation by length has also been demonstrated. Partial separation (enrichment) according to bandgap (which is linked to polarizability) has also been shown and can be improved to full separation of individual types of semiconducting SWNTs with better control over operational parameters and the length of SWNT starting material. This process and device can be scaled affordably to generate useful amounts of semiconducting SWNTs for electronic device development and production. In this study, a flow injection dielectrophoresis technique was used with a modified dielectrophoresis device. The length, width, and height of the modified chamber were 28, 2.5, and 0.025 cm, respectively. On the bottom of the chamber, there are two arrays of 50-m-wide, 2-m-thick gold electrodes, which are connected to an AC voltage generator and are alternately arranged so that every electrode is adjacent to two electrodes of the opposite polar. There is an additional plate electrode on the top of the chamber that is negatively biased. During the experiment, a syringe pump constantly pumps in the mobile phase, 1-percent sodium dodecylbenzene sulfonate (SDBS) solution, into the chamber. The frequency and voltage are set to 1 MHz and 10 V peak-to-peak, respectively. About 150 micro-L of SWNTs in 1- percent SDBS decanted solution are injected to the mobile phase through a septum near the entrance of the chamber. The flow rate of the mobile phase is set to 0.02 cu cm/min. The injected SWNTs sample flows through the chamber before it is lead into a fluorescence flow-through cell and collected for further analysis. The flow-through cell has three windows, thus allowing the fluorometer to collect fluorescence

  12. Conjugated polymer-assisted dispersion of single-wall carbon nanotubes: the power of polymer wrapping.

    PubMed

    Samanta, Suman Kalyan; Fritsch, Martin; Scherf, Ullrich; Gomulya, Widianta; Bisri, Satria Zulkarnaen; Loi, Maria Antonietta

    2014-08-19

    The future application of single-walled carbon nanotubes (SWNTs) in electronic (nano)devices is closely coupled to the availability of pure, semiconducting SWNTs and preferably, their defined positioning on suited substrates. Commercial carbon nanotube raw mixtures contain metallic as well as semiconducting tubes of different diameter and chirality. Although many techniques such as density gradient ultracentrifugation, dielectrophoresis, and dispersion by surfactants or polar biopolymers have been developed, so-called conjugated polymer wrapping is one of the most promising and powerful purification and discrimination strategies. The procedure involves debundling and dispersion of SWNTs by wrapping semiflexible conjugated polymers, such as poly(9,9-dialkylfluorene)s (PFx) or regioregular poly(3-alkylthiophene)s (P3AT), around the SWNTs, and is accompanied by SWNT discrimination by diameter and chirality. Thereby, the π-conjugated backbone of the conjugated polymers interacts with the two-dimensional, graphene-like π-electron surface of the nanotubes and the solubilizing alkyl side chains of optimal length support debundling and dispersion in organic solvents. Careful structural design of the conjugated polymers allows for a selective and preferential dispersion of both small and large diameter SWNTs or SWNTs of specific chirality. As an example, with polyfluorenes as dispersing agents, it was shown that alkyl chain length of eight carbons are favored for the dispersion of SWNTs with diameters of 0.8-1.2 nm and longer alkyls with 12-15 carbons can efficiently interact with nanotubes of increased diameter up to 1.5 nm. Polar side chains at the PF backbone produce dispersions with increased SWNT concentration but, unfortunately, cause reduction in selectivity. The selectivity of the dispersion process can be monitored by a combination of absorption, photoluminescence, and photoluminescence excitation spectroscopy, allowing identification of nanotubes with specific

  13. Single-Wall Carbon Nanotube Field Effect Transistors with Non-Volatile Memory Operation

    NASA Astrophysics Data System (ADS)

    Sakurai, Tatsuya; Yoshimura, Takeshi; Akita, Seiji; Fujimura, Norifumi; Nakayama, Yoshikazu

    2006-10-01

    We describe the fabrication and electrical characteristics of single-wall carbon-nanotubes field-effect transistors (CNT-FETs) with a non-volatile memory function using ferroelectric thin films as gate insulators. The ferroelectric-gate CNT-FETs were fabricated using single-wall CNTs synthesized from alcohol by catalytic chemical vapor deposition and sol-gel derived PbZr0.5Ti0.5O3 thin films. The ferroelectric-gate CNT-FETs showed modulation of the drain current with the gate voltage and the threshold voltage shift (memory window) on the drain current-gate voltage characteristics. Moreover, the memory window was saturated around 1.1 V as the gate voltage sweeping range increased. These results indicate that carriers in CNTs are controlled by spontaneous polarization of the ferroelectric films. Because ferroelectrics exhibit complex couplings between their electrical, structural, mechanical, thermal, and optical properties, and because CNTs have unique mechanical and electrical properties, ferroelectric-gate CNT-FETs offer promise as potentially useful nanoelectronics devices not only for non-volatile memory elements but also for high-sensitivity sensors.

  14. Mechanism of Synthesis of Ultra-Long Single Wall Carbon Nanotubes in Arc Discharge Plasma

    SciTech Connect

    Keidar, Michael

    2013-06-23

    In this project fundamental issues related to synthesis of single wall carbon nanotubes (SWNTs), which is relationship between plasma parameters and SWNT characteristics were investigated. Given that among plasma-based techniques arc discharge stands out as very advantageous in several ways (fewer defects, high flexibility, longer lifetime) this techniques warrants attention from the plasma physics and plasma technology standpoint. Both experimental and theoretical investigations of the plasma and SWNTs synthesis were conducted. Experimental efforts focused on plasma diagnostics, measurements of nanostructures parameters, and nanoparticle characterization. Theoretical efforts focused to focus on multi-dimensional modeling of the arc discharge and single wall nanotube synthesis in arc plasmas. It was demonstrated in experiment and theoretically that controlling plasma parameters can affect nanostucture synthesis altering SWNT properties (length and diameter) and leading to synthesis of new structures such as a few-layer graphene. Among clearly identified parameters affecting synthesis are magnetic and electric fields. Knowledge of the plasma parameters and discharge characteristics is crucial for ability to control synthesis process by virtue of both magnetic and electric fields. New graduate course on plasma engineering was introduced into curriculum. 3 undergraduate students were attracted to the project and 3 graduate students (two are female) were involved in the project. Undergraduate student from Historically Black University was attracted and participated in the project during Summer 2010.

  15. Effects of single-walled carbon nanotubes on the bioavailability of PCBs in field-contaminated sediments

    EPA Science Inventory

    Adsorption of hydrophobic organic contaminants (HOCs) to black carbon is a well studied phenomenon. One emerging class of engineered black carbon materials are single-walled carbon nanotubes (SWNT). Little research has investigated the potential of SWNT to adsorb and sequester HO...

  16. Replacement of Transparent Conductive Oxides by Single-Wall Carbon Nanotubes in Cu(In,Ga)Se2-Based Solar Cells

    SciTech Connect

    Contreras, M. A.; Barnes, T.; van de Lagemaat, J.; Rumbles, G.; Coutts, T. J.; Weeks, C.; Glatkowski, P.; Levitsky, I.; Peltola, J.; Britz, D. A.

    2007-01-01

    Thin films of single-wall carbon nanotubes were used as the transparent top electrical contact in Cu(In,Ga)Se{sub 2}- based solar cells. Specifically, we demonstrate that thin layers of carbon nanotubes in combination with insulating polymer layers can effectively replace the metal oxide layers typically used in polycrystalline thin-film solar cells. Replacing the standard n-type ZnO layer with a thin film of carbon nanotubes yielded energy conversion efficiencies up to 13%. The optical and electrical transport properties of the single-wall carbon nanotubes suggest that suitable applications for these materials include multiple-junction solar cells, thermophotovoltaics, and other applications benefiting from a p-type transparent conductor with high near-infrared transmission.

  17. Chirality specific and spatially uniform synthesis of single-walled carbon nanotubes from a sputtered Co-W bimetallic catalyst.

    PubMed

    An, Hua; Kumamoto, Akihito; Takezaki, Hiroki; Ohyama, Shinnosuke; Qian, Yang; Inoue, Taiki; Ikuhara, Yuichi; Chiashi, Shohei; Xiang, Rong; Maruyama, Shigeo

    2016-08-14

    Synthesis of single-walled carbon nanotubes (SWNTs) with well-defined atomic arrangements has been widely recognized in the past few decades as the biggest challenge in the SWNT community, and has become a bottleneck for the application of SWNTs in nano-electronics. Here, we report a selective synthesis of (12, 6) SWNTs with an enrichment of 50%-70% by chemical vapor deposition (CVD) using sputtered Co-W as a catalyst. This is achieved under much milder reduction and growth conditions than those in the previous report using transition-metal molecule clusters as catalyst precursors (Nature, 2014, 510, 522). Meanwhile, in-plane transmission electron microscopy unambiguously identified an intermediate structure of Co6W6C, which is strongly associated with selective growth. However, most of the W atoms disappear after a 5 min CVD growth, which implies that anchoring W may be important in this puzzling Co-W system. PMID:27412697

  18. Single charge detection in capacitively coupled integrated single electron transistors based on single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhou, Xin; Ishibashi, Koji

    2012-09-01

    Single charge detection is demonstrated in the capacitively coupled integrated single electron transistors (SETs) in single-walled carbon nanotubes (SWCNTs) quantum dots. Two SETs are fabricated based on two different SWCNTs aligned in parallel, by taking advantage of the aligned growth of SWCNTs and subsequent transfer-printed techniques. In order to make both two SETs be capacitively coupled, a metal finger is fabricated on the top of them. The charge sensing is proved by the response of a detector current in one SWCNT-SET when the number of electrons in the other SWCNT-SET is changed by sweeping the corresponding gate voltages. In this integrated device, shifts of Coulomb oscillation peaks due to the single electron event are also observed.

  19. Thin-film transistors using DNA-wrapped semiconducting single-wall carbon nanotubes with selected chiralities

    NASA Astrophysics Data System (ADS)

    Kuwahara, Yuki; Nihey, Fumiyuki; Ohmori, Shigekazu; Saito, Takeshi

    2015-10-01

    Selected semiconducting chiralities, (7,5), (7,6), and (8,4), of DNA-wrapped single-wall carbon nanotubes (DNA-SWCNTs) were used for thin-film transistors (TFTs). Chirality separation was carried out by ion exchange chromatography (IEX) with the ssDNA of the (TAT)4 sequence. An on/off ratio of 3.8 × 106 with a carrier mobility of 11 cm2/(V·s) was successfully achieved in the fabricated SWCNT-TFTs. The comparison between the on/off ratios obtained before (101-102) and after IEX (104-107) indicated that the IEX separation process sufficiently improves the performance of SWCNT-TFTs because of the reducing metallic SWCNT pathways in the TFT channel.

  20. Near-infrared photoconductive and photovoltaic devices using single-wall carbon nanotubes in conductive polymer films

    NASA Astrophysics Data System (ADS)

    Kazaoui, S.; Minami, N.; Nalini, B.; Kim, Y.; Hara, K.

    2005-10-01

    We have fabricated prototypical Al/single-wall carbon nanotube (SWNT)-polymer/indium tin oxide thin-film devices that exhibit promising photoconductive and photovoltaic responses in a broad spectral range, typically from 300 to 1600 nm. This achievement was made possible by finely dispersed SWNT powders in polymer matrices such as poly-phenylene-vinylene and poly-thiophene. These devices utilize (i) the intrinsic near-infrared light harvesting properties of semiconducting SWNTs, (ii) the electronic transport properties of both semiconducting and metallic SWNTs in combination with those of the polymer matrices, and (iii) probably charge/energy transfer processes between SWNTs and the polymers. By selecting different sources of SWNTs and polymers, we have shown that the optoelectronic properties of these devices are potentially tunable. To support our investigation, several techniques including spectrally resolved photoconductivity, optical absorption, and photoluminescence spectroscopy were utilized.

  1. Carboxylic-group-functionalized single-walled carbon nanohorns as peroxidase mimetics and their application to glucose detection.

    PubMed

    Zhu, Shuyun; Zhao, Xian-En; You, Jinmao; Xu, Guobao; Wang, Hua

    2015-09-21

    Carboxylic-group-functionalized single-walled carbon nanohorns (SWCNHs-COOH) have been found to possess peroxidase-like activity for the first time. Similar to natural peroxidase, SWCNHs-COOH can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine by H2O2 to produce a blue color solution. Compared with horseradish peroxidase, SWCNHs-COOH exhibit higher activity and stability under harsh reaction conditions. The catalytic activity of SWCNHs-COOH depends on the concentration of H2O2. A colorimetric method for glucose detection was developed by combining the SWCNH-COOH catalytic reaction and the generation of H2O2 by the enzymatic oxidation of glucose with glucose oxidase. Taking into account the advantages of good stability, high biocompatibility in aqueous solutions, being metal-catalyst free, and high purity, SWCNHs-COOH are expected to have potential applications in biotechnology and clinical diagnostics as enzymatic mimics. PMID:26247806

  2. Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

    SciTech Connect

    Xie, Xu; Islam, Ahmad E.; Seabron, Eric; Dunham, Simon N.; Du, Frank; Lin, Jonathan; Wilson, William L.; Rogers, John A.; Wahab, Muhammad A.; Alam, Muhammad A.; Li, Yuhang; Tomic, Bojan; Huang, Jiyuan; Burns, Branden; Song, Jizhou; Huang, Yonggang

    2015-04-07

    Aligned arrays of semiconducting single-walled carbon nanotubes (s-SWNTs) represent ideal configurations for use of this class of material in high performance electronics. Development of means for removing the metallic SWNTs (m-SWNTs) in as-grown arrays represents an essential challenge. Here, we introduce a simple scheme that achieves this type of purification using direct, selective current injection through interdigitated electrodes into the m-SWNTs, to allow their complete removal using processes of thermocapillarity and dry etching. Experiments and numerical simulations establish the fundamental aspects that lead to selectivity in this process, thereby setting design rules for optimization. Single-step purification of arrays that include thousands of SWNTs demonstrates the effectiveness and simplicity of the procedures. The result is a practical route to large-area aligned arrays of purely s-SWNTs with low-cost experimental setups.

  3. Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Xie, Xu; Wahab, Muhammad A.; Li, Yuhang; Islam, Ahmad E.; Tomic, Bojan; Huang, Jiyuan; Burns, Branden; Seabron, Eric; Dunham, Simon N.; Du, Frank; Lin, Jonathan; Wilson, William L.; Song, Jizhou; Huang, Yonggang; Alam, Muhammad A.; Rogers, John A.

    2015-04-01

    Aligned arrays of semiconducting single-walled carbon nanotubes (s-SWNTs) represent ideal configurations for use of this class of material in high performance electronics. Development of means for removing the metallic SWNTs (m-SWNTs) in as-grown arrays represents an essential challenge. Here, we introduce a simple scheme that achieves this type of purification using direct, selective current injection through interdigitated electrodes into the m-SWNTs, to allow their complete removal using processes of thermocapillarity and dry etching. Experiments and numerical simulations establish the fundamental aspects that lead to selectivity in this process, thereby setting design rules for optimization. Single-step purification of arrays that include thousands of SWNTs demonstrates the effectiveness and simplicity of the procedures. The result is a practical route to large-area aligned arrays of purely s-SWNTs with low-cost experimental setups.

  4. Semiconducting single-walled carbon nanotubes sorting with a removable solubilizer based on dynamic supramolecular coordination chemistry

    NASA Astrophysics Data System (ADS)

    Toshimitsu, Fumiyuki; Nakashima, Naotoshi

    2014-10-01

    Highly pure semiconducting single-walled carbon nanotubes (SWNTs) are essential for the next generation of electronic devices, such as field-effect transistors and photovoltaic applications; however, contamination by metallic SWNTs reduces the efficiency of their associated devices. Here we report a simple and efficient method for the separation of semiconducting- and metallic SWNTs based on supramolecular complex chemistry. We here describe the synthesis of metal-coordination polymers (CP-Ms) composed of a fluorene-bridged bis-phenanthroline ligand and metal ions. On the basis of a difference in the ‘solubility product’ of CP-M-solubilized semiconducting SWNTs and metallic SWNTs, we readily separated semiconducting SWNTs. Furthermore, the CP-M polymers on the SWNTs were simply removed by adding a protic acid and inducing depolymerization to the monomer components. We also describe molecular mechanics calculations to reveal the difference of binding and wrapping mode between CP-M/semiconducting SWNTs and CP-M/metallic SWNTs. This study opens a new stage for the use of such highly pure semiconducting SWNTs in many possible applications.

  5. Thin film transistors using preferentially grown semiconducting single-walled carbon nanotube networks by water-assisted plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kim, Un Jeong; Lee, Eun Hong; Kim, Jong Min; Min, Yo-Sep; Kim, Eunseong; Park, Wanjun

    2009-07-01

    Nearly perfect semiconducting single-walled carbon nanotube random network thin film transistors were fabricated and their reproducible transport properties were investigated. The networked single-walled carbon nanotubes were directly grown by water-assisted plasma-enhanced chemical vapor deposition. Optical analysis confirmed that the nanotubes were mostly semiconductors without clear metallic resonances in both the Raman and the UV-vis-IR spectroscopy. The transistors made by the nanotube networks whose density was much larger than the percolation threshold also showed no metallic paths. Estimation based on the conductance change of semiconducting nanotubes in the SWNT network due to applied gate voltage difference (conductance difference for on and off state) indicated a preferential growth of semiconducting nanotubes with an advantage of water-assisted PECVD. The nanotube transistors showed 10-5 of on/off ratio and ~8 cm2 V-1 s-1 of field effect mobility.

  6. Thin film transistors using preferentially grown semiconducting single-walled carbon nanotube networks by water-assisted plasma-enhanced chemical vapor deposition.

    PubMed

    Kim, Un Jeong; Lee, Eun Hong; Kim, Jong Min; Min, Yo-Sep; Kim, Eunseong; Park, Wanjun

    2009-07-22

    Nearly perfect semiconducting single-walled carbon nanotube random network thin film transistors were fabricated and their reproducible transport properties were investigated. The networked single-walled carbon nanotubes were directly grown by water-assisted plasma-enhanced chemical vapor deposition. Optical analysis confirmed that the nanotubes were mostly semiconductors without clear metallic resonances in both the Raman and the UV-vis-IR spectroscopy. The transistors made by the nanotube networks whose density was much larger than the percolation threshold also showed no metallic paths. Estimation based on the conductance change of semiconducting nanotubes in the SWNT network due to applied gate voltage difference (conductance difference for on and off state) indicated a preferential growth of semiconducting nanotubes with an advantage of water-assisted PECVD. The nanotube transistors showed 10(-5) of on/off ratio and approximately 8 cm2 V(-1) s(-1) of field effect mobility. PMID:19567966

  7. Templated Synthesis of Single-Walled Carbon Nanotubes with Specific Structure.

    PubMed

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

    2016-04-19

    Single-walled carbon nanotubes (SWNTs) have shown great potential in various applications attributed to their unique structure-dependent properties. Therefore, the controlled preparation of chemically and structurally pristine SWNTs is a crucial issue for their advanced applications (e.g., nanoelectronics) and has been a great challenge for two decades. Epitaxial growth from well-defined seeds has been shown to be a promising strategy to control the structure of SWNTs. Segments of carbon nanotubes, including short pipes from cutting of preformed nanotubes and caps from opening of fullerenes or cyclodehydrogenation of polycyclic hydrocarbon precursors, have been used as the seeds to grow SWNTs. Single-chirality SWNTs were obtained with both presorted chirality-pure SWNT segments and end caps obtained from polycyclic hydrocarbon molecules with designed structure. The main challenges of nanocarbon-segment-seeded processes are the stability of the seeds, yield, and efficiency. Catalyst-mediated SWNT growth is believed to be more efficient. The composition and morphology of the catalyst nanoparticles have been widely reported to affect the chirality distribution of SWNTs. However, chirality-specific SWNT growth is hard to achieve by alternating catalysts. The specificity of enzyme-catalyzed reactions brings us an awareness of the essentiality of a unique catalyst structure for the chirality-selective growth of SWNTs. Only catalysts with the desired atomic arrangements in their crystal planes can act as structural templates for chirality-specific growth of SWNTs. We have developed a new family of catalysts, tungsten-based intermetallic compounds, which have high melting points and very special crystal structures, to facilitate the growth of SWNTs with designed chirality. By the use of W6Co7 catalysts, (12,6) SWNTs were directly grown with purity higher than 92%. Both high-resolution transmission electron microscopy measurements and density functional theory simulations

  8. Water Encapsulation Control in Individual Single-Walled Carbon Nanotubes by Laser Irradiation.

    PubMed

    Chiashi, Shohei; Hanashima, Tateki; Mitobe, Ryota; Nagatsu, Kotaro; Yamamoto, Takahiro; Homma, Yoshikazu

    2014-02-01

    Owing to one-dimensionality, nanoscale curvature, and high chemical stability, single-walled carbon nanotubes (SWNTs) have unique surfaces for gas molecules: outer surface as adsorption (exohedral) site and inner surface that provides encapsulation (endohedral) space. Because as-grown SWNTs have different structure (chirality and diameter) and they are normally bundled, it is extremely difficult to investigate the intrinsic properties of SWNTs as adsorbent. Here we demonstrate controlling adsorption and encapsulation states of water in individual suspended SWNTs using laser irradiation with monitoring of their behavior by photoluminescence measurement and perform molecular dynamics simulation. The laser heating and the pressure control make water molecules encapsulated or ejected for SWNTs, which are individually oxidized and opened with laser heating. The precise control of oxidization makes it possible to observe the cluster formation of water molecules during the encapsulation process and to confine water molecules inside SWNTs even in vacuum. PMID:26276583

  9. Self-Assembling Peptide Coatings Designed for Highly Luminescent Suspension of Single-Walled Carbon Nanotubes

    PubMed Central

    Tsyboulski, Dmitri A.; Bakota, Erica L.; Witus, Leah S.; Rocha, John-David R.; Hartgerink, Jeffrey D.; Weisman, R. Bruce

    2009-01-01

    A series of self-assembling multidomain peptides have been designed, synthesized, and tested for their ability to individually suspend single-walled carbon nanotubes (SWCNTs) in water while preserving strong near-IR nanotube luminescence. Photometric and spectral measurements on individual SWCNTs revealed that emission in the common biocompatible coating agents Pluronic F127, ss-DNA, and BSA is approximately an order of magnitude weaker than in the bio-incompatible ionic surfactant SDBS. By contrast, one of the engineered peptides gave SWCNT emission ~40% as intense as in SDBS. A strong inverse correlation was also found between the spectral line widths of coated SWCNTs and the efficiency of their emission. Peptides with rationally designed self-assembly properties appear to be promising coatings that may enable SWCNT optical sensing applications in biological environments. PMID:19053447

  10. Predicting excitonic gaps of semiconducting single-walled carbon nanotubes from a field theoretic analysis

    DOE PAGESBeta

    Konik, Robert M.; Sfeir, Matthew Y.; Misewich, James A.

    2015-02-17

    We demonstrate that a non-perturbative framework for the treatment of the excitations of single walled carbon nanotubes based upon a field theoretic reduction is able to accurately describe experiment observations of the absolute values of excitonic energies. This theoretical framework yields a simple scaling function from which the excitonic energies can be read off. This scaling function is primarily determined by a single parameter, the charge Luttinger parameter of the tube, which is in turn a function of the tube chirality, dielectric environment, and the tube's dimensions, thus expressing disparate influences on the excitonic energies in a unified fashion. Asmore » a result, we test this theory explicitly on the data reported in [NanoLetters 5, 2314 (2005)] and [Phys. Rev. B 82, 195424 (2010)] and so demonstrate the method works over a wide range of reported excitonic spectra.« less

  11. Evaluation of nonlocal parameter in the vibrations of single-walled carbon nanotubes with initial strain

    NASA Astrophysics Data System (ADS)

    Arash, B.; Ansari, R.

    2010-06-01

    Based upon a nonlocal shell model accounting for the small-scale effects, the vibration characteristics of single-walled carbon nanotubes (SWCNTs) with different boundary conditions subjected to initial strain are studied in this paper. The set of governing equations of motion is numerically solved by a method that emerged from incorporating the radial point interpolation approximation within the framework of the generalized differential quadrature method. The effectiveness of the present nonlocal shell model is assessed by the molecular dynamics simulations as a benchmark of good accuracy. Accordingly, nonlocal parameters for clamped and cantilever SWCNTs with thicknesses of 0.066 and 0.34 nm are proposed due to the uncertainty that exists in defining nanotube wall thickness. The simulation results show that the resonant frequencies of SWCNTs are very sensitive to the initial strain, although small.

  12. Investigation on optical absorption properties of ion irradiated single walled carbon nanotubes

    SciTech Connect

    Vishalli, Dharamvir, Keya; Kaur, Ramneek; Raina, K. K.; Avasthi, D. K.; Jeet, Kiran

    2015-08-28

    In the present study change in the optical absorption properties of single walled carbon nanotubes (SWCNTs) under nickel ion (60 MeV) irradiation at various fluences has been investigated. Langmuir Blodgett technique is used to deposit SWCNT thin film of uniform thickness. AFM analysis shows a network of interconnected bundles of nanotubes. UV-Vis-NIR absorption spectra indicate that the sample mainly contain SWCNTs of semiconducting nature. It has been found in absorption spectra that there is decrease in the intensity of the characteristic SWCNT peaks with increase in fluence. At fluence value 1×10{sup 14} ions/cm{sup 2} there is almost complete suppression of the characteristic SWCNTs peaks.The decrease in the optical absorption with increase in fluence is due to the increase in the disorder in the system which leads to the decrease in optically active states.

  13. Interaction of [FeFe]-Hydrogenases with Single-walled Carbon Nanotubes

    SciTech Connect

    Chang, D. S.; McDonald, T. J.; Kim, Y.-H.; Blackburn, J. L.; Heben, M. J.; King, P. W.

    2007-01-01

    Single-walled carbon nanotubes (SWNT) are promising candidates for use in energy conversion devices as an active photo-collecting elements, for dissociation of bound excitons and charge-transfer from photo-excited chromophores, or as molecular wires to transport charge. Hydrogenases are enzymes that efficiently catalyze the reduction of protons from a variety of electron donors to produce molecular hydrogen. Hydrogenases together with SWNT suggest a novel biohybrid material for direct conversion of sunlight into H{sub 2}. Here, we report changes in SWNT optical properties upon addition of recombinant [FeFe] hydrogenases from Clostridium acetobutylicum and Chlamydomonas reinhardtii. We find evidence that novel and stable charge-transfer complexes are formed under conditions of the hydrogenase catalytic turnover, providing spectroscopic handles for further study and application of this hybrid system.

  14. Acute toxicity of a mixture of copper and single-walled carbon nanotubes to Daphnia magna.

    PubMed

    Kim, Ki T; Klaine, Stephen J; Lin, Sijie; Ke, Pu C; Kim, Sang D

    2010-01-01

    Nanomaterials released into the environment will interact with many materials including other contaminants. This may influence bioavailability and fate of both the nanoparticles and the other contaminants. The present study examined the effect of a combination of soluble copper and surface-modified single-walled carbon nanotubes (SWNTs) on Daphnia magna. Lysophosphatidylcholine (LPC) was used to modify the surface of SWNTs, reducing the surface hydrophobicity of the tubes and thereby producing a stable aqueous nanoparticle suspension. The toxicity of the nanoparticle-copper (Cu) mixture was determined to be additive. The addition of nontoxic concentration of LPC-SWNTs enhanced the uptake and toxicity of copper. Greater amounts of Cu were shown to accumulate in D. magna upon addition of 0.5 and 1.0 mg/L LPC-SWNTs. PMID:20821426

  15. Conducting and transparent single-wall carbon nanotube electrodes for polymer-fullerene solar cells

    NASA Astrophysics Data System (ADS)

    Pasquier, Aurelien Du; Unalan, Husnu Emrah; Kanwal, Alokik; Miller, Steve; Chhowalla, Manish

    2005-11-01

    We describe the use of single-wall carbon nanotube (SWNT) thin films as transparent and conducting electrodes for hole collection in poly(hexyl)thiophene-[6-6]phenyl-C61-butyric acid methyl ester (P3HT-PCBM) organic photovoltaics. We report a power conversion efficiency of 1%, with a fill factor of 0.3 and a short-circuit current of 6.5mA/cm2 under 100mW/cm2 polychromatic white light illumination measured in air. These values are comparatively higher than reference cells of similar thickness made on indium tin oxide (ITO) glass substrates. This is attributed to the three-dimensional nature of the interface between the SWNTs and the P3HT-PCBM nanocomposite. Our results indicate that solution processed SWNT thin films are a viable alternative to ITO for photovoltaic devices, eliminating an expensive vacuum deposition step in the fabrication of organic solar cells.

  16. Toughening of epoxy matrices with reduced single-walled carbon nanotubes.

    PubMed

    Martinez-Rubi, Yadienka; Ashrafi, Behnam; Guan, Jingwen; Kingston, Christopher; Johnston, Andrew; Simard, Benoit; Mirjalili, Vahid; Hubert, Pascal; Deng, Libo; Young, Robert J

    2011-07-01

    Reduced single-walled carbon nanotubes (r-SWCNT) are shown to react readily at room temperature under inert atmosphere conditions with epoxide moieties, such as those in triglycidyl p-amino phenol (TGAP), to produce a soft covalently bonded interface around the SWCNT. The soft interface is compatible with the SWCNT-free cross-linked cured matrix and acts as a toughener for the composite. Incorporation of 0.2 wt % r-SWCNT enhances the ultimate tensile strength, toughness and fracture toughness by 32, 118, and 40%, respectively, without change in modulus. A toughening rate (dK(IC)/dwt(f)) of 200 MPa m(0.5) is obtained. The toughening mechanism is elucidated through dynamic mechanical analyses, Raman spectroscopy and imaging, and stress-strain curve analyses. The method is scalable and applicable to epoxy resins and systems used commercially. PMID:21612292

  17. Electrical and mechanical characterisation of single wall carbon nanotubes based composites for tissue engineering applications.

    PubMed

    Whulanza, Yudan; Battini, Elena; Vannozzi, Lorenzo; Vomero, Maria; Ahluwalia, Arti; Vozzi, Giovanni

    2013-01-01

    This paper presents the realisation of conductive matrices for application to tissue engineering research. We used poly(L-lactide (PLLA)), poly(epsilon-caprolactone) (PCL), and poly(lactide-co-glycolide) (PLGA) as polymer matrix, because they are biocompatible and biodegradable. The conductive property was integrated to them by adding single wall carbon nanotubes (SWNTs) into the polymer matrix. Several SWNTs concentrations were introduced aiming to understand how they influence and modulate mechanical properties, impedance features and electric percolation threshold of polymer matrix. It was observed that a concentration of 0.3% was able to transform insulating matrix into conductive one. Furthermore, a conductive model of the SWNT/polymer was developed by applying power law of percolation threshold. PMID:23646716

  18. Molecular design of strong single-wall carbon nanotube/polyelectrolyte multilayer composites

    NASA Astrophysics Data System (ADS)

    Mamedov, Arif A.; Kotov, Nicholas A.; Prato, Maurizio; Guldi, Dirk M.; Wicksted, James P.; Hirsch, Andreas

    2002-11-01

    The mechanical failure of hybrid materials made from polymers and single-wall carbon nanotubes (SWNT) is primarily attributed to poor matrix-SWNT connectivity and severe phase segregation. Both problems can be successfully mitigated when the SWNT composite is made following the protocol of layer-by-layer assembly. This deposition technique prevents phase segregation of the polymer/SWNT binary system, and after subsequent crosslinking, the nanometre-scale uniform composite with SWNT loading as high as 50 wt% can be obtained. The free-standing SWNT/polyelectrolyte membranes delaminated from the substrate were found to be exceptionally strong with a tensile strength approaching that of hard ceramics. Because of the lightweight nature of SWNT composites, the prepared free-standing membranes can serve as components for a variety of long-lifetime devices.

  19. Photoluminescence Imaging of Oxygen Doped Individual Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Yalcin, Sibel Ebru; Yamaguchi, Hisato; Galande, Charudatta; Crochet, Jared J.; Mohite, Aditya D.; Gupta, Gautam; Ma, Xuedan; Htoon, Han; Doorn, Stephen K.; Los Alamos National Laboratory Collaboration; Rice University Collaboration

    2014-03-01

    Semiconducting single-walled carbon nanotubes (SWNTs) are attractive candidates for near-IR optoelectronic applications. But they show low fluorescence quantum yield. Recent oxygen doping studies have shown that the quantum yield of the excitons can be enhanced by an order of magnitude due to the formation of local 0D sites on the SWNT surface. However, these studies have been limited to ensemble measurements. Understanding the dopant site, exciton migration and trapping dynamics on individual SWNTs is critical for controllably tuning the photo-physical behavior. We have studied ozonated individual (6,5) nanotubes as a function of progressive ozonation. We spatially resolved the pristine and doped state using visible and NIR sensitive cameras. We demonstrate PL imaging as a probe of the emission dynamics as a function of dopant concentration. The spectral studies show the red-shifted emission in the PL of the NTs due to the ozonated site.

  20. Roll to plate printed stretchable silver electrode using single walled carbon nanotube on elastomeric substrate.

    PubMed

    Jung, Minhun; Noh, Jinsoo; Kim, Junseok; Kim, Donghwan; Cho, Gyoujin

    2013-08-01

    Stretchable electronics may open new applications in display, sensors and actuators. To attain the stretchable electronics, the ink formulation should be compatible with elastomeric substrates. Here, we present the formulation of silver nanoparticles and single walled carbon nanotubes (SWNTs) for printing stretchable silver electrodes on the elastomeric substrates. Highly conductive stretchable electrodes can be printed directly on the poly(styrene-b-butadiene-b-styrene) (PSBS) substrates by roll to plate (R2P) gravure printer. During the stretching test, R2P printed silver based stretchable electrodes show the high conductivity of 1000 S cm(-1) at 0.27 wt% of SWNT loading. Furthermore, the resistance of the printed silver electrode was not changed up to 15% of tensile strain. PMID:23882805