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1

Process for separating metallic from semiconducting single-walled carbon nanotubes  

NASA Technical Reports Server (NTRS)

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.

Sun, Ya-Ping (Inventor)

2008-01-01

2

Reversible Oxidation Effect in Raman Scattering from Metallic Single-Wall Carbon Zhonghua Yu and Louis E. Brus*  

E-print Network

. More interestingly, in Raman scattering from metallic carbon nano- tubes, the tangential C-C stretchingLETTERS Reversible Oxidation Effect in Raman Scattering from Metallic Single-Wall Carbon NanotubesVed: June 16, 2000; In Final Form: August 23, 2000 Raman scattering from individual single-wall carbon

3

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

PubMed

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

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

2014-10-21

4

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

5

Observing and predicting the preferential functionalization of metallic or semiconducting single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The functionalization of single-walled carbon nanotubes was performed with four organic molecules. A careful study involving thermo-gravimetric analysis and Raman spectroscopy allowed us to quantify the grafting rate of each molecule, and to evidence a preferential grafting of metallic or semiconducting tube depending on the molecule under consideration. In order to understand the origin of this selectivity, we performed DFT calculations of the electronic structure of the molecules, and compared it to the electron density of states of carbon nanotubes. This approach allowed us to propose a paradigm for explaining the grafting affinity of organic molecules towards metallic or semiconducting nanotubes, and for estimating the grafting efficiency. It could further be used in order to predict the selectivity of any molecule containing a double or triple carbon bond towards metallic or semiconducting carbon nanotubes.

Nicolle, Jimmy; Le Goff, Xavier F.; Grandjean, Agnès; Cambedouzou, Julien

2014-09-01

6

Double Layer Charging for Conductivity Enhancement of Pure Metallic and Semiconducting Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Injecting high electronic charge densities can profoundly change the optical, electrical, and magnetic properties of materials. Evidence suggests a possibility of significantly improving conductivity of carbon nanotubes through double layer charge injection. Double layer charge injection can prove to be a powerful method when applied to carbon nanotubes because of theirs high surface area and chemical stability. Investigation has commenced on the effect of charging on various types of carbon nanotubes, specifically 99% purified single wall semiconducting and single wall metallic tubes. An electrical double layer is electrochemically introduced upon a sheet of carbon nanotubes via application of potential (up to ±5 volts) to a sample immersed in ionic-liquid-based electrolyte. Resistance of carbon nanotube as a function of applied charging voltage is recorded to determine the effects of charge injection. Results show that the electrical double layer considerably reduces the resistance across both samples. ESR/LFMA studies combined with low temperature magnetic and transport measurements are conducted to search for charge injection induced superconductivity in carbon nanotubes.

Mayo, Nathanael; Kuznetsov, Alexander; Zakhidov, Anvar

2011-03-01

7

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

SciTech Connect

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.

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

2008-01-01

8

Residual metal impurity AIDS facile in situ electrochemical surface derivatization of single-walled carbon nanotubes.  

PubMed

Residual metal impurities were exploited as reactants in the functionalization of the surface of single-walled carbon nanotubes (SWCNT) with nickel hexacyanoferrate (NiHCF) by simple electrochemical cycling in ferricyanide solutions. This facile in situ electrochemical modification process provides intimate contact between NiHCF and SWCNTs that improves the stability of the redox property and reactivity of NiHCF. The characteristic redox behavior of NiHCF on SWCNT surfaces can be used as an electrochemical probe to access qualitative and quantitative information on unknown electroactive metal impurities in SWCNTs. Significantly, the NiHCF-modified SWCNTs exhibit pseudocapacitive behavior, and the calculated specific capacitances are 710 and 36?F?g(-1) for NiHCF-SWCNTs and SWCNTs respectively. Furthermore, NiHCF-SWCNTs were transformed into Ni(OH)2 /SWCNTs and used for enzymeless glucose oxidation. PMID:25179740

Boopathi, Sidhureddy; Sudha, Rajagopal; Senthil Kumar, Shanmugam; Lakshminarasimha Phani, Kanala

2014-11-01

9

Effects of hydrogen adsorption on single-wall carbon nanotubes: Metallic hydrogen decoration O. Gulseren,1,2  

E-print Network

Effects of hydrogen adsorption on single-wall carbon nanotubes: Metallic hydrogen decoration O. Gu of carbon nanotubes undergo dramatic changes with hydrogen chemisorption from first principle calculations other isomers can be insulating. For both zigzag and armchair nanotubes, hydrogenation of each carbon

Yildirim, Taner

10

Metallic single-walled, carbon nanotube temperature sensor with self heating  

NASA Astrophysics Data System (ADS)

A metallic single-walled carbon nanotube (SWCNT) has been proposed as a highly sensitive temperature sensor with consideration of self-heating induced scattering. This sensor can be implemented to sense temperature spanning from 20º C to 400º C with high temperature coefficient of resistivity (TCR) ranging from 0.0035/ºC to 0.009/ ºC. Important aspect of this work is consideration of self-heating in SWCNT which was not considered in earlier carbon nanotube based temperature sensors. We have studied a metallic SWCNT over a silicon dioxide substrate and in between two metal contacts. Bias voltage of 0.1V has been applied in between these two contacts. For resistivity calculation, we have utilized one-dimensional semi-classical transport model assuming SWCNT is perfectly conducting. The heat flow equation has been solved assuming steady state flow of heat. We have also assumed that contact and substrate are in thermal equilibrium with the surroundings. Since self-heating significantly affects electro-thermal transport, incorporation of this phenomenon enables to design and model ambient temperature sensor accurately. We have studied CNT sensor with different lengths and chiralities. The results show that resistances of longest (3?m) and thinnest (9, 0) CNTs increase rapidly with temperature. For a 3?m long metallic SWCNT with chirality index (9, 0), TCR has the maximum value (~0.009/ ºC).

Mohsin, K. M.; Banadaki, Y. M.; Srivastava, A.

2014-04-01

11

Hydrogen Storage in Metal-Modified Single-Walled Carbon Nanotubes Channing C. Ahn, John J. Vajoa  

E-print Network

graphene layers as shown below. The stacking sequence is a- K-a-b, in which the a and b designation sequences for potassium layers. Each potassium layer of the Stage 2 compound is separated by an a-b grapheneHydrogen Storage in Metal-Modified Single-Walled Carbon Nanotubes Channing C. Ahn, John J. Vajoa

12

Exciton states in metallic zigzag single-walled carbon nanotubes under uniaxial strain  

NASA Astrophysics Data System (ADS)

The exciton energy spectrum and its binding energy under the uniaxial strain have been theoretically studied by using the tight-binding model in the metallic zigzag single-walled carbon nanotubes (SWNTs). It is found that the energy of M11- and M22- excitons and their binding energies increase with the increase of uniaxial strain, but the energy of M11+ and M22+ excitons and their binding energies decrease as the uniaxial strain increase. So, we can deduce that the splitting of M11 and M22 exciton will disappear as the uniaxial strain increases up to some degree, which is expected to be detected by the future experiment. On the other hand, it is interesting to calculate the exciton energy spectrum and binding energies of the bands that nearest to the Fermi level, with a narrow gap under the uniaxial strain. The obtained results show that they increase with increasing the uniaxial strain, based on which a supplemented tool is offered to detect the deformation degree of a metallic SWNT under uniaxial strain. In addition, we expect the results obtained here can offer some useful information for the future THz applications.

Yu, Guili; Li, Guichen; Jia, Yonglei; Tang, Gang

2014-11-01

13

Single-wall nanotubes produced by metal-catalyzed disproportionation of carbon monoxide  

Microsoft Academic Search

Isolated single-wall carbon nanotubes (SWNT) were grown by disproportionation of carbon monoxide at 1200°C, catalyzed by molybdenum particles a few nanometers in size. The tube diameters, ranging from 1 to 5 nm, closely correlated with the size of the catalytic particle found attached to the tube end. This result represents the first experimental evidence of SWNT produced by pre-formed catalytic

Hongjie Dai; Andrew G. Rinzler; Pasha Nikolaev; Andreas Thess; Daniel T. Colbert; Richard E. Smalley

1996-01-01

14

Evaluation of metallic and semiconducting single-walled carbon nanotube characteristics  

NASA Astrophysics Data System (ADS)

The nature of the mixed electronic type metallic (M-) and semiconducting (S-) single-walled carbon nanotubes (SWNTs) synthesized by current methods has posed a key challenge for the development of high performance SWNT-based electronic devices. The precise measurements of M- to S-SWNT ratio in as-grown or separated samples are of paramount importance for the controlled synthesis, separation and the realization of various applications. The objective of this review is to provide comprehensive overview of the progress achieved so far for measuring the M/S ratio both on individual and collective levels of SWNT states. We begin with a brief introduction of SWNT structures/properties and discussion of the problems and difficulties associated with precise measurement of the M/S ratio, and then introduce the principles for obtaining distinguished signals from M-and S-SWNTs. These techniques are classified into different groups based either on the single/ensemble detection of SWNT samples or on the principles of techniques themselves. We then present the M/S ratio evaluation results of these methods, with emphasis on scanning probe microscopy (SPM)-based detection techniques. Finally, the prospects of precise and large-scale measurement of M/S ratio in achieving controlled synthesis and understanding growth mechanism of SWNTs are discussed.

Wu, Bin; Geng, Dechao; Liu, Yunqi

2011-05-01

15

On the Preferential Growth of Metallic Single-Walled Carbon Nanotubes Thin Films  

NASA Astrophysics Data System (ADS)

The lack of reasonably homogeneous single walled carbon nanotube (SWCNT) materials hinders their ubiquitous applications. There have been significant achievements in separating SWCNTs according to their conductivity and in enriching the distribution of nanotubes with a specific conductivity. Meanwhile, despite studies regarding direct control over carbon nanotube structure during growth, there is only a limited understanding of exactly what determines carbon nanotube chirality during catalytic growth and, thereby, the electronic structure of grown SWCNT. Here we report the results of the studies of growth of SWCNTs thin films from Fe nanocatalysts deposited onto a SiO2/Si support and in situ annealed in a He or Ar ambient that contains various ratios of H2 and H2O. Our investigations reveal that the variation of the noble gas ambient during thermal conditioning of the catalyst, in combination with oxidative and reductive species, alters the fraction of tubes with metallic conductivity from about 20% of the population to a maximum of 91%. The tubes have been identified based on Raman, photoluminescence and electrical (field effect transistor performance) characterizations by using special prepared reference sample. In situ environmental transmission electron microscopy observations of the SiO2 supported Fe nanocatalysts in H2O, H2/H2O, Ar/H2O and He/H2O gaseous environments reveal that presence of Ar in the ambient leads to significant coarsening of nanocatalysts with rounded surface morphology, while under He ambient the nanocatalyst is more faceted. Various scenarios such as adsorption and roughening induced morphology rearrangements of the catalyst particles and their relationships with grown tubes electronic structures will be presented.

Harutyunyan, Avetik

2010-03-01

16

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

17

Evaluation of semiconducting/metallic ratio of single wall carbon nanotubes by resonant Raman scatterings-excel  

NASA Astrophysics Data System (ADS)

We investigated single wall carbon nanotubes (SWCNTs) synthesized by the HiPCO method and further processed with nitronium hexafluoroantimonate (NO2SbF6 : NHFA) treatment using continuous resonant Raman scattering in the range of 570-900 nm. According to the population ratio calculation results from Raman scattering data, it is obvious that semiconducting SWCNTs with small diameter and metallic SWCNTs were selectively removed by NHFA.

Min, Kyoung In; Kim, Ki Kang; Oh, Myoung-Kyu; Choi, Soo Bong; Rho, Heesuk; Lee, Ha Jin; An, Kay Hyeok; Choi, Young Chul; Han, Jong Hun; Oh, Kyung Hui; Lee, Young-Hee; Jeong, Mun Seok

2010-08-01

18

Metal-oxide-layer-coated single-walled carbon nanotubes as a sensor for trace amounts of oxygen  

NASA Astrophysics Data System (ADS)

We found that resistive sensors using a single-walled carbon nanotube thin film covered with a SrTiO3 or CeO2 thin layer exhibit excellent responses to trace amounts (˜10-3 Pa) of oxygen. By analysis based on the Langmuir adsorption model, their responses were revealed to be due to O2 adsorption on the metal oxide layer, which involves two adsorption processes. They were assigned to identical adsorptions as superoxide species on the sites at separate locations on the metal oxide surface, i.e., at directly accessible flat areas and at recessed areas that are only accessible via thermally activated surface diffusion.

Tabata, Hiroshi; Fukuda, Hiroshi; Matsushita, Kazutoshi; Kubo, Osamu; Kikuchi, Tsutomu; Sato, Tetsuya; Kamimura, Takahiro; Ueda, Tsuyoshi; Shimazaki, Ryotaro; Tanjo, Hiromasa; Horiuchi, Masashi; Katayama, Mitsuhiro

2014-03-01

19

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

NASA Astrophysics Data System (ADS)

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.

Hamadanian, Masood; Tavangar, Zahra; Noori, Banafsheh

2014-11-01

20

Catalytic Routes Towards Single Wall Carbon Nanotubes  

Microsoft Academic Search

Single wall carbon nanotubes (SWCNT) have become a strategic material in the area of nanotechnologies nowadays, and catalytic chemical vapor deposition seems to be the most promising technique in view of an industrial?scale production. However, the selective catalytic production of single wall carbon nanotubes is still a challenge, since catalytic systems performances both in terms of selectivity and activity are

Emmanuel Lamouroux; Philippe Serp; Philippe Kalck

2007-01-01

21

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

NASA Technical Reports Server (NTRS)

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.

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

22

The effect of the catalyst metals on the thermal-oxidative stability of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this work, we analyzed the effect of the catalyst metals with various forms on the thermal-oxidative stability of single-walled carbon nanotubes (SWCNTs) by using thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and electronic dispersive X-ray spectroscopy (EDX). The results indicate that the catalyst metal nanoparticles encapsulated inside multi-shelled graphite particles play a main role on destabilizing SWCNTs during their air oxidation. We also compared the thermal stability of SWCNTs in the cloth-like soot and the cotton-like soot produced by arc-discharge. The SWCNTs in the cotton-like soot are of higher thermal-oxidation stability than that in the cloth-like soot due to fewer multi-shelled graphite nanoparticles encapsulating metal nanoparticles.

Wu, Chuxin; Xu, Jiaoxing; Li, Jiaxin; Dong, Guofa; Guan, Lunhui

2009-08-01

23

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

SciTech Connect

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.

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

24

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

NASA Astrophysics Data System (ADS)

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.

Wilson, Kenneth

25

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

PubMed

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 (?) 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 (?) 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

Adeleye, Adeyemi S; Keller, Arturo A

2014-02-01

26

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

27

Raman spectroscopy of single wall carbon nanotubes  

E-print Network

A single wall carbon nanotube (SWNT) is a new form of carbon, whose atomic arrangement is equivalent to a graphene sheet rolled into a cylinder in a seamless way. The typical diameter of a SWNT ranges from 0.6 nm to several ...

Son, HyungBin, 1981-

2008-01-01

28

Hydrogen Storage in metal-modified single-walled carbon nanotubes  

SciTech Connect

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 proportional to the logarithm of the pressure. Using 300 K for room temperature, the 100 bar pressure requirement is reduced to exp(-900/300) 100 bar = 5 bar at room temperature. This is in the pressure range used for prior experimental work such as that of Colin and Herold in the late 1960's and early 1970's.

Dr. Ahn

2004-04-30

29

Monitoring of heavy metal lead in environmental water sample by single-wall carbon nanotubes preconcentration hyphenated with ICP-MS  

Microsoft Academic Search

In order to evaluate the effects of heavy metals discharged in the use of fossil energy sources on the environment, a novel method using a microcolumn packed with single-walled carbon nanotubes (SWNTs) as a new adsorption material was developed for the preconcentration of trace Pb in environmental water sample prior to its monitoring by inductively coupled plasma mass spectrometry (ICP-MS).

Dengbo Lu

2010-01-01

30

Assembly of single wall carbon nanotube-metal nanohybrids using biomolecular components  

NASA Astrophysics Data System (ADS)

Biomaterials such as nucleic acids and proteins can be exploited to create higher order structures. The biomolecular components such as DNA and peptides have been used to assemble nanoparticles with high fidelity. Here, we use DNA and peptides, and their preferential interaction with inorganic and carbon nanomaterials to form homogeneous hybrids. The enhanced binding of Pt ions to both DNA and peptide functionalized nanoparticles mediates the assembly of carbon nanotubes functionalized with DNA with peptide coated gold nanoparticles.

Kim, Sang Nyon; Slocik, Joseph M.; Naik, Rajesh R.

2010-08-01

31

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

32

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

NASA Astrophysics Data System (ADS)

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.

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

33

Electrically robust metal nanowire network formation by in-situ interconnection with single-walled carbon nanotubes.  

PubMed

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

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

34

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

PubMed Central

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

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

35

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

SciTech Connect

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.

Lukaszczuk, Pawel, E-mail: plukaszczuk@zut.edu.pl [West Pomeranian University of Technology, Institute of Chemical and Environment Engineering, ul. Pulaskiego 10, 70-322 Szczecin (Poland)] [West Pomeranian University of Technology, Institute of Chemical and Environment Engineering, ul. Pulaskiego 10, 70-322 Szczecin (Poland); Ruemmeli, Mark H.; Knupfer, Martin [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstr. 20, 01069 Dresden (Germany)] [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstr. 20, 01069 Dresden (Germany); Kalenczuk, Ryszard J.; Borowiak-Palen, Ewa [West Pomeranian University of Technology, Institute of Chemical and Environment Engineering, ul. Pulaskiego 10, 70-322 Szczecin (Poland)] [West Pomeranian University of Technology, Institute of Chemical and Environment Engineering, ul. Pulaskiego 10, 70-322 Szczecin (Poland)

2012-03-15

36

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

PubMed

One-dimensional conductive fillers such as single-walled carbon nanotubes (SWNTs) can be aggregated and aligned during transparent conductive film (TCF) formation by the vacuum filtration method. The potential error of analysing the average sheet resistance of these anisotropic films, using the four-point probe in-line method and the conversion formula developed assuming uniform isotropic material properties, was systematically investigated by finite element analysis and experiments. The finite element analysis of anisotropic stripe-patterned TCFs with alternating low (?1) and high (?2) resistivities revealed that the estimated average sheet resistance approached ?1/t when the probes were parallel to the aligned nanotubes. The thickness of the film is t. It was more close to ?2/t when the probes were perpendicular to the aligned tubes. Indeed, TCFs fabricated by the vacuum filtration method using metal-enriched SWNTs exhibited highly anisotropic local regions where tubes were aggregated and aligned. The local sheet resistances of randomly oriented, aligned, and perpendicular tube regions of the TCF at a transmittance of 89.9% were 5000, 2.4, and 12?300 ? ?(-1), respectively. Resistivities of the aggregated and aligned tube region (?1 = 1.2 × 10(-5) ? cm) and the region between tubes (?2 = 6.2 × 10(-2) ? cm) could be approximated with the aid of finite element analysis. This work demonstrates the potential error of characterizing the average sheet resistance of anisotropic TCFs using the four-point probe in-line method since surprisingly high or low values could be obtained depending on the measurement angle. On the other hand, a better control of aggregation and alignment of nanotubes would realize TCFs with a very small anisotropic resistivity and a high transparency. PMID:25075461

Kang, Hosung; Kim, Duckjong; Baik, Seunghyun

2014-09-21

37

1. CVD SWNT single-walled carbon  

E-print Network

1. CVD SWNT single-walled carbon nanotube, SWNT SWNT 1993 Iijima SWNT 1) 2) SWNT SWNT depositionCVD SWNT CVD 1 SWNT TEM #12; SWNT SWNT CVD CVD CVD 1996 CVD SWNT 3) HiPco 4)CoMoCAT 5)HiPco CoMoCAT SWNT CoMoCAT CVD CVD 6,7) 8) 9) CVD SWNT

Maruyama, Shigeo

38

Optical modulation of single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Recent advances in the spectroscopy of single walled carbon nanotubes have significantly enhanced our ability to understand and control their surface chemistry, both covalently and non-covalently. Our work has focused on modulating the optical properties of semiconducting single walled carbon nanotubes as near infrared photoluminescent sensors for chemical analysis. Molecular detection using near-infrared light between 0.9 and 1.3 eV has important biomedical applications because of greater tissue penetration and reduced auto-fluorescent background in thick tissue or whole-blood media. In one system, the transition of DNA secondary structure modulates the dielectric environment of the single-walled carbon nanotube (SWNT) around which it is adsorbed. The SWNT band-gap fluorescence undergoes a red shift when an encapsulating 30-nucleotide oligomer is exposed to counter ions that screen the charged backbone. We demonstrate the detection of the mercuric ions in whole blood, tissue, and from within living mammalian cells using this technology. Similar results are obtained for DNA hybridization and the detection of single nucleotide polymorphism. We also report the synthesis and successful testing of near-infrared ?-D-glucose sensors2 that utilize a different mechanism: a photoluminescence modulation via charge transfer. The results demonstrate new opportunities for nanoparticle optical sensors that operate in strongly absorbing media of relevance to medicine or biology.

Strano, Michael S.

2007-03-01

39

Synthesis and Characterization of Hybrid Metal-Metal and Metal-Oxide Nanostructure Decorated Single Walled Carbon Nanotube Devices  

E-print Network

nano-gas sensors in a facile and cost effective route, a process that can be extended to other metal oxidenano-gas sensors in a facile and cost effective route, a process that can be extended to other metal oxide

Hernandez, Sandra Catalina

2010-01-01

40

Progress towards monodisperse single-walled carbon nanotubes  

Microsoft Academic Search

The defining characteristic of a nanomaterial is that its properties vary as a function of its size. This size dependence can be clearly observed in single-walled carbon nanotubes, where changes in structure at the atomic scale can modify the electronic and optical properties of these materials in a discontinuous manner (for example, changing metallic nanotubes to semiconducting nanotubes and vice

Mark C. Hersam

2008-01-01

41

Chapter 2 Simulation of Single Walled Carbon Nano Tubes SWNT  

E-print Network

13 Chapter 2 Simulation of Single Walled Carbon Nano Tubes SWNT 2.1 Introduction Carbon nanotubes, mechanical and vibrational properties of single-walled carbon nano tubes SWNT," G. Gao, T. Cagin, and W properties of single-walled carbon nano tubes with di erent radius and chirality armchair n, n, chiral 2n, n

Goddard III, William A.

42

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles  

E-print Network

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles Presenting Antibody Stimuli the body using single walled carbon nanotube (SWNT) bundles presenting antibody stimuli. Owing to the large of lymphocytes, useful for basic science applications and clinical immunotherapy. Single walled carbon nanotubes

Fahmy, Tarek

43

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

NASA Astrophysics Data System (ADS)

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 separation. By using salts with different anionic groups (cholate, Cl-, I-, and SCN-), it is concluded that the SWCNT separation using salt solutions is mainly driven by the cations in the solution. Additionally, different methods for depositing separated SWCNTs on glass substrates are described. In one method, SWCNTs are first isolated from their surfactant by introducing organic solvents such as methanol or acetone to aqueous suspensions of previously separated m- and/or sc-SWCNTs. Following the induced SWCNT dissolution, desired nanomaterials can be redispersed directly in another solvent, such as methanol, for deposition on substrates. In another method, separated SWCNTs are deposited on glass substrates by the process of evaporation driven self-assembly. Different morphologies on the substrate are formed by changing the viscosity of the evaporating SWCNT/SDS suspensions. The results are described using the Stokes-Einstein equation for diffusion in one dimension.

Ashour, Rakan F.

44

Production of carbon single wall nanotubes versus experimental parameters  

NASA Astrophysics Data System (ADS)

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

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

1998-08-01

45

Exohydrogenated single-wall carbon nanotubes T. Yildirim,1  

E-print Network

of hydrogen and nano- tube system. Hydrogen-carbon interactions have been studied exten- sively bothExohydrogenated single-wall carbon nanotubes T. Yildirim,1 O. Gu¨lseren,1,2 and S. Ciraci3 1 NIST exohydrogenated zigzag (n,0) and armchair (n,n) single-wall carbon nanotubes (CnHn), polyhedral molecules

Yildirim, Taner

46

Metal-functionalized single-walled graphitic carbon nitride nanotubes: a first-principles study on magnetic property  

PubMed Central

The magnetic properties of metal-functionalized graphitic carbon nitride nanotubes were investigated based on first-principles calculations. The graphitic carbon nitride nanotube can be either ferromagnetic or antiferromagnetic by functionalizing with different metal atoms. The W- and Ti-functionalized nanotubes are ferromagnetic, which are attributed to carrier-mediated interactions because of the coupling between the spin-polarized d and p electrons and the formation of the impurity bands close to the band edges. However, Cr-, Mn-, Co-, and Ni-functionalized nanotubes are antiferromagnetic because of the anti-alignment of the magnetic moments between neighboring metal atoms. The functionalized nanotubes may be used in spintronics and hydrogen storage. PMID:21711614

2011-01-01

47

Band Gap Fluorescence from Individual Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.

O'Connell, Michael J.; Bachilo, Sergei M.; Huffman, Chad B.; Moore, Valerie C.; Strano, Michael S.; Haroz, Erik H.; Rialon, Kristy L.; Boul, Peter J.; Noon, William H.; Kittrell, Carter; Ma, Jianpeng; Hauge, Robert H.; Weisman, R. Bruce; Smalley, Richard E.

2002-07-01

48

Local thermal elevation probing of metal nanostructures during laser illumination utilizing surface-enhanced Raman scattering from a single-walled carbon nanotube.  

PubMed

Localized laser-induced heating of an individual Au nano-dimer was quantitatively evaluated by measuring the surface-enhanced Raman scattering (SERS) from an isolated single-walled carbon nanotube (SWNT) supported above the nano-gap between the two metal centres of the dimer. The SERS measurement showed an apparent wavenumber shift in the G-band of the Raman spectra with an increase in the power of the illuminated laser light, indicating the laser-induced local thermal elevation of the Au nano-dimer. In addition, it was found that the effect of the laser illumination on the thermal elevation in air was larger than that in aqueous solution, indicating that the localized laser-heating effect is strongly influenced by the surrounding environment. The present technique provides a measure of the highly localized heating effect of plasmonic metal nanostructures under photo-illumination. PMID:23416759

Takase, Mai; Nabika, Hideki; Hoshina, Shinji; Nara, Masanobu; Komeda, Kei-ichiro; Shito, Ryukou; Yasuda, Satoshi; Murakoshi, Kei

2013-03-28

49

CVD Growth of Single-Walled Carbon Nanotubes Shigeo Maruyama  

E-print Network

CVD Growth of Single-Walled Carbon Nanotubes Shigeo Maruyama Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan maruyama@photon.t.u-tokyo.ac.jp CVD growth of single-walled carbon nanotubes (SWNTs) will be discussed with recent alcohol CVD experiments incorporating nitrogen, molecular

Maruyama, Shigeo

50

Improvements in Production of Single-Walled Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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 modification for conversion from batch to continuous production.

Balzano, Leandro; Resasco, Daniel E.

2009-01-01

51

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

NASA Astrophysics Data System (ADS)

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 × 105.

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

2014-09-01

52

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

PubMed

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

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

2010-11-23

53

Chirality Characterization of Dispersed Single Wall Carbon Nonotubes.  

National Technical Information Service (NTIS)

The physical properties of a single wall carbon nanotube (SWNT) depend on its chirality, which is determined by two integer coefficients, normally denoted by (n, m). The spectroscopy methods of fluorescence, Raman scattering and optical absorption have be...

M. Namkung, P. A. Williams, C. D. Mayweather, B. Wincheski, C. Park

2005-01-01

54

Single wall carbon nanotubes: Separation and applications to biosensors  

NASA Astrophysics Data System (ADS)

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 specific antigen detection are explained. Signal amplification strategies are introduced by using redox mediator, enzyme, and enzyme-decorated carbon nanotubes.

Kim, Sang Nyon

55

Center for Applications of Single-Walled Carbon Nanotubes  

SciTech Connect

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.

Resasco, Daniel E

2008-02-21

56

Method of solubilizing shortened single-walled carbon nanotubes in organic solutions  

US Patent & Trademark Office Database

Naked single-walled nanotube carbon metals and semiconductors were dissolved in organic solutions by derivatization with SOCl.sub.2 and octadecylamine charge. Both ionic (charge transfer) and covalent solution phase chemistry with concomitant modulation of the single-walled carbon nanotubes (SWNT) band structure were demonstrated. Solution phase near-IR spectroscopy was used to study the effects of chemical modifications on the band gaps of the SWNTs. Reaction of solubilized SWNTs with dichlorocarbene led to functionalization of the nanotube walls.

2001-12-18

57

Diameter-dependent solubility of single-walled carbon nanotubes.  

PubMed

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

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

58

Single Wall Carbon Nanotube-Based Structural Health Sensing Materials  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

59

Laser ablation process for single-walled carbon nanotube production  

NASA Technical Reports Server (NTRS)

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.

Arepalli, Sivaram

2004-01-01

60

Synthesis and Characterization of Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) were synthesized by ablating a graphite target mixed with metal catalysts by either the primary (1064nm) or the second harmonic (532nm) beam of a pulsed Nd:YAG laser at high temperature. Materials synthesized under different conditions were characterized by x-ray diffraction, AFM, TEM, ESR, and micro-Raman techniques. The morphology of the materials produced is similar to those by the dual laser[1] and catalyst-assisted arc-discharge[2] methods. The raw material was found to consist of 60-70% SWNTs. Micro-Raman measurements show a narrow diameter distribution. The average diameter of the nanotubes varies with the experimental parameters. [1] A. Thess et al. Science 273, 483(1996). [2] C. Journet et al. Nature 388, 756 (1997).

Bower, C.; Zhou, O.; Jin, L.; Paulson, S.; Superfine, R.; McNeil, L.; Suzuki, S.; Tanigaki, K.

1998-03-01

61

Individual single-walled carbon nanotubes as electrochemical probes  

NASA Astrophysics Data System (ADS)

We have performed cyclic voltammetry measurements using individual single-walled carbon nanotubes as working electrodes. The nanotubes were first grown on silicon oxide substrates and contacted using titanium. An insulating layer was then deposited and sub-micron-sized windows opened, leaving only the sidewalls of selected nanotubes exposed. These devices were exposed to an electrolyte containing redox-active ferrocene derivatives and cyclic voltammetry measurements were performed. Our results suggest that metallic nanotubes behave as ideal cylindrical electrodes and exhibit a diffusion-limited redox current. The behavior of semiconducting nanotubes is more complex due to the interplay between band bending, quantum capacitance and the potential drop at the liquid-nanotube interface.

Lemay, S. G.; Heering, H. A.; Heller, I.; Kong, J.; Williams, K. A.; Dekker, C.

2004-03-01

62

Electrochemical Sensing with Individual Single-Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

The transport properties of molecular electronic devices can be strongly modulated by immersion in a liquid electrolyte. For example, early investigations with single-wall carbon nanotubes (SWNTs) used the electrolyte as a "liquid gate." That is, the conductance of SWNTs in a field-effect-transistor configuration was tuned via an electrochemical potential applied to the electrolyte. This concept was also extended to sensor applications in which molecules impinging upon the SWNT surface cause a rearrangement of screening ions and a corresponding change of the device conductance. In these approaches, the coupling between the device and the electrolyte is solely electrostatic, and no charge is transferred across the liquid-device interface. Here we demonstrate that individual SWNTs can also be used as electrodes for electron transfer reactions, that is, electrochemical reactions in which electrons are exchanged between a SWNT and redox-active molecules in solution. The rate of electron transfer to SWNTs is observed to be very fast. It can nonetheless be resolved in dc transport measurements due to the high diffusive flux of redox molecules resulting from the nanometer diameter of SWNTs. Interestingly, metallic and semiconducting SWNTs yield similar current-voltage characteristics; we show that this behaviour is consistent with theories of electron transfer in which the electronic structure of the SWNTs is explicitly taken into account. Finally, we demonstrate that noble metals can be controllably and selectively electrodeposited from aqueous solution unto individual single-wall carbon nanotubes, opening new routes for the functionalization of SWNT devices. Work done with K. Besteman, H. A. Heering, I. Heller, J. Kong, J.-O Lee, B. M. Quinn, F.G.M. Wiertz, K. A. Williams and C. Dekker.

Lemay, Serge

2005-03-01

63

Measurements of Electronic Transport Properties of Single-Walled Carbon Nanotubes Encapsulating Alkali-Metals and C60 Fullerenes via Plasma Ion Irradiation  

Microsoft Academic Search

We report on the measurements of the electronic transport properties of Cs-encapsulated single-walled carbon nanotubes (SWNTs), Li-encapsulated SWNTs, and C60-encapsulated SWNTs synthesized by plasma ion irradiation method. After fabricating field-effect transistor (FET) configurations using pristine and plasma-ion-irradiated SWNTs, the electronic transport properties of these devices are investigated in vacuum at room temperature. As a result, C60-encapsulated SWNTs give rise to

Takeshi Izumida; Goo-Hwan Jeong; Yoichiro Neo; Takamichi Hirata; Rikizo Hatakeyama; Hidenori Mimura; Kenji Omote; Yasuhiko Kasama

2005-01-01

64

(SWNT; single-walled carbon nanotube) (CVD; chemical vapor deposition)  

E-print Network

1. 1993 (1) (SWNT; single-walled carbon nanotube) (2) SWNT (CVD; chemical vapor deposition) SWNT CVD CVD CVD (ACCVD; alcohol catalytic chemical vapor deposition) (3) (4) mm (5) SWNT SWNT (6),(7) SWNT SWNT CVD (COCCVD; carbon monoxide catalytic chemical vapor

Maruyama, Shigeo

65

Strain controlled thermomutability of single-walled carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes are superior materials for thermal management and phononic device use due to their extremely high thermal conductivity and unique one-dimensional geometry. Here we report a systematic investigation of the effects of mechanical tensile, compressive and torsional strain on the thermal conductivity of single-walled carbon nanotubes using molecular dynamics simulation. In contrast to conventional predictions for solids, an unexpected

Zhiping Xu; Markus J. Buehler

2009-01-01

66

Local Electronic Structure of Single-Walled Carbon Nanotubes from  

E-print Network

Local Electronic Structure of Single-Walled Carbon Nanotubes from Electrostatic Force Microscopy An atomic force microscope was used to locally perturb and detect the charge density in carbon nanotubes. Changing the tip voltage varied the Fermi level in the nanotube. The local charge density increased

Bockrath, Marc

67

Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

68

Single walled carbon nanotube thin films: Properties and applications  

Microsoft Academic Search

The work presented in this thesis discusses the synthesis, purification, dispersion, characterization and deposition of single walled carbon nanotubes (SWNTs). Specifically, the deposition of SWNT thin films, their optoelectronic properties, and applications in organic photovoltaic devices and thin film transistors (TFTs) is reported. The motivation for this work has been to understand the opto-electronic properties of SWNTs in order to

Husnu Emrah Unalan

2006-01-01

69

Chemical Sensing with Polyaniline Coated Single-Walled Carbon Nanotubes  

SciTech Connect

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.

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

2011-01-25

70

Mechanical Properties of Pressure Quenched Single Wall Carbon Nanotubes  

Microsoft Academic Search

Single wall carbon nanotube (SWNT) samples were compressed in a diamond anvil cell to 36 GPa and studied by in-situ x-ray diffraction at a synchrotron source and by Raman spectroscopy. The samples were quenched from high pressure and nanoindentation studies of the recovered material were performed. Raman studies on the quenched sample show retention of the original features with an

Jeremy Patterson; Yogesh Vohra

2001-01-01

71

Electronic Raman Scattering On Individual Semiconducting Single Walled Carbon Nanotubes  

PubMed Central

We report experimental measurements of electronic Raman scattering by electrons (holes) in individual single-walled carbon nanotubes (SWNTs) under resonant conditions. The Raman scattering at low frequency range reveals a single particle excitation feature. And the dispersion of electronic structure around the center of Brillouin zone of a semiconducting SWNT (14, 13) is extracted. PMID:25095891

Chen, Xi; Zhu, Bairen; Zhang, Anmin; Zeng, Hualing; Zhang, Qingming; Cui, Xiaodong

2014-01-01

72

Elastic properties of single-walled carbon nanotubes  

Microsoft Academic Search

Analytical expressions for the velocities of the longitudinal and the torsional sound waves in single-walled carbon nanotubes are derived using Born's perturbation technique within a lattice-dynamical model. These expressions are compared to the formulas for the velocities of the sound waves in an elastic hollow cylinder from the theory of elasticity to obtain analytical expressions for the Young's and shear

V. N. Popov; V. E. Van Doren; M. Balkanski

2000-01-01

73

Photoconductivity of single-walled carbon nanotubes under CW illumination.  

E-print Network

Photoconductivity of single-walled carbon nanotubes under CW illumination. I. A. Levitsky Emitech nanotubes (SWNTs) has been studied under CW illumination in the NIR (900 � 1800 nm) and far-IR (9-10 ����m state or continuous wave (CW) illumination presents interest not only for a fundamental understanding

Euler, William B.

74

Thermogravimetric Analysis of Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

Arepalli, Sivram; Nikolaev, Pavel; Gorelik, Olga

2010-01-01

75

Low-temperature synthesis of high-purity single-walled carbon nanotubes from alcohol  

Microsoft Academic Search

By using alcohol as the carbon source, a new simple catalytic chemical vapor deposition technique to synthesize high-purity single-walled carbon nanotubes at low temperature is demonstrated. Because of the etching effect of decomposed OH radical attacking carbon atoms with a dangling bond, impurities such as amorphous carbon, multi-walled carbon nanotubes, metal particles and carbon nanoparticles are completely suppressed even at

Shigeo Maruyama; Ryosuke Kojima; Yuhei Miyauchi; Shohei Chiashi; Masamichi Kohno

2002-01-01

76

Thermionic Emission of Single-Wall Carbon Nanotubes Measured  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

77

Chirality Characterization of Dispersed Single Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

78

Synthesis of Single-Wall Carbon Nanotubes from Diesel Soot  

NASA Astrophysics Data System (ADS)

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.

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

79

Single Wall Carbon Nano Tube Films and Coatings  

Microsoft Academic Search

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

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

2002-01-01

80

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

NASA Astrophysics Data System (ADS)

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 nanotubes are highly conductive, transparent, and flexible as well. Based on transferred nanotube arrays on fabric, we have successfully demonstrated nanotube transistors with on/off ratios ˜ 105, and chemical sensors for low-concentration NO2 and 2,4,6-trinitrotoluene (TNT). In Chapter 5, I present the study of transparent conductive thin films made with two kinds of commercial carbon nanotubes: HiPCO and arc-discharge nanotubes. These films have been further exploited as hole-injection electrodes for organic light emitting diodes (OLEDs) on both rigid glass and flexible substrates. Our experiments reveal that films based on arc discharge nanotubes are overwhelmingly better than HiPCO-nanotube-based films in all the critical aspects, including the surface roughness, sheet resistance, and transparency. The optimized films show a typical sheet resistance of ˜160O/? at 87% transparency and have been successfully used to make OLEDs with high stability and long lifetime. Lastly, I present the fast and scalable integration of nanowire chemical sensors with micromachined hotplates built on SiN membranes. These hotplates allowed nanowire chemical sensors to operate at elevated temperatures in order to enhance the sensitivity of chemical sensors to target gases. By applying different current through the platinum heating filament, we can easily vary the device temperature from room temperature to 350°C. These nanosensors with integrated hot plates have been exploited for the detection of ethanol, CO and hydrogen down to concentrations of 1 ppm, 10 ppm and 50 ppm, respectively.

Ryu, Koungmin

81

Solid–liquid–solid growth mechanism of single-wall carbon nanotubes  

Microsoft Academic Search

Reasons are presented which suggest that the liquefaction of the catalytic particles is a decisive condition for formation of single wall carbon nanotubes (SWNTs) by physical synthesis techniques. It is argued that the SWNT growth mechanism is a kind of solid–liquid–solid graphitization of amorphous carbon or other imperfect carbon forms catalyzed by molten supersaturated carbon–metal nanoparticles. The assumption of low

A Gorbunov; O Jost; W Pompe; A Graff

2002-01-01

82

Effects of electron irradiation on single-walled carbon nanotubes  

Microsoft Academic Search

An experimental investigation of the effects of electron irradiation on Single-Walled Carbon Nanotubes (SWNTs) was conducted. The study focused on the modifications induced to the SWNT structure. SWNTs were irradiated at room temperature using a Transmission Electron Microscope (TEM) at 120eV. The effects of irradiation were observed and characterised using electron microscopy and Raman spectroscopy. Samples of SWNTs were observed

Katherine McDonell; Gwénaëlle Proust; Luming Shen

2010-01-01

83

Elastic properties of single-walled carbon nanotubes in compression  

Microsoft Academic Search

Quenched molecular dynamics simulations are used to investigate the elastic behavior of open-ended, free-standing, single wall, carbon nanotubes. Interatomic interactions are described by a Tersoff-Brenner potential. The tubes' response to axial compression is examined and typical failure modes as well as stress-strain curves for a number of tube radii are shown. Data collected are used to calculate Young's modulus for

C. F. Cornwell; L. T. Wille

1997-01-01

84

Length-dependent extraction of single-walled carbon nanotubes.  

PubMed

A two-phase liquid-liquid extraction process is presented which is capable of extracting water-soluble single-walled carbon nanotubes into an organic phase. The extraction utilizes electrostatic interactions between a common phase transfer agent and the sidewall functional groups on the nanotubes. Large length-dependent van der Waals forces for nanotubes allow the ability to control the length of nanotubes extracted into the organic phase as demonstrated by atomic force microscopy. PMID:16351177

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

2005-12-01

85

Fermi energy dependence of the G-band resonance Raman spectra of single-wall carbon nanotubes  

E-print Network

The Fermi energy dependence of the G-band resonance Raman spectra of single-wall carbon nanotubes (SWNTs) is calculated, including the Kohn anomaly effect for metallic tubes. The gate voltage dependence of the G-band Raman ...

Park, J. S.

86

Molecular junctions by joining single-walled carbon nanotubes.  

PubMed

Crossing single-walled carbon nanotubes can be joined by electron beam welding to form molecular junctions. Stable junctions of various geometries are created in situ in a transmission electron microscope. Electron beam exposure at high temperatures induces structural defects which promote the joining of tubes via cross-linking of dangling bonds. The observations are supported by molecular dynamics simulations which show that the creation of vacancies and interstitials induces the formation of junctions involving seven- or eight-membered carbon rings at the surface between the tubes. PMID:12190529

Terrones, M; Banhart, F; Grobert, N; Charlier, J-C; Terrones, H; Ajayan, P M

2002-08-12

87

Mixing at 50 GHz using a single-walled carbon nanotube transistor Sami Rosenblatt,a  

E-print Network

Mixing at 50 GHz using a single-walled carbon nanotube transistor Sami Rosenblatt,a Hao Lin, Vera have probed the electrical properties of top-gated single-walled carbon nanotube transistors­6 As a result, they offer promise as very high-frequency transistors. A short single-walled carbon nanotube

McEuen, Paul L.

88

Optical Characterization and Applications of Single Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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 have a tunable n-IR emission that responds to changes in the local dielectric function but remains stable to permanent photobleaching. We report the synthesis and successful testing of solution phase, near-infrared sensors, with ?-D-glucose sensing as a model system, using single walled carbon nanotubes that modulate their emission in response to the adsorption of specific biomolecules. New types of non-covalent functionalization using electron withdrawing molecules are shown to provide sites for transferring electrons in and out of the nanotube. We also show two distinct mechanisms of signal transduction -- fluorescence quenching and charge transfer. The results demonstrate new opportunities for nanoparticle optical sensors that operate in strongly absorbing media of relevance to medicine or biology.

Strano, Michael S.

2005-03-01

89

Aligned arrays of single walled carbon nanotubes for transparent electronics  

NASA Astrophysics Data System (ADS)

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

Du, Frank; Rogers, John A.

2013-06-01

90

Demetalization of single-walled carbon nanotube thin films with microwave irradiation  

NASA Astrophysics Data System (ADS)

The microwave irradiation effects on purified HiPCO and CoMoCat single-walled carbon nanotube (SWNT) thin films are investigated. The surface conductivities of the SWNT films are extracted from the measured THz transmission coefficients to provide a direct indication of the metallic content in the films. The observed drastic conductivity decrease indicates a significant metallic content reduction after the microwave irradiation. Two different laser excitations are applied for Raman spectroscopy to reveal the response of different nanotube species. The Raman spectra of both HiPCO and CoMoCat thin films confirm the decrease of metallic carbon nanotubes. The observed microwave-induced effects may potentially lead to a convenient scheme for demetalization of single-walled carbon nanotube mixtures.

Wang, Lu; Xiong, Yao; Wu, Ziran; Duong, Binh; Seraphin, Supapan; Xin, Hao; Chen, Liwei

2011-02-01

91

Tunable intertube spacing in single-walled carbon nanotube bundles  

SciTech Connect

The structure of ternary compounds involving alkali, tetrahydrofuran (THF) and single-walled carbon nanotubes have been investigated using neutron diffraction (ND). Hydrogen-deuterium substitution in THF, as well as the study of different alkali-based compounds, allow a layered structure around the nanotubes to be determined. ND results indicate that the alkali cations form a monolayer surrounding each tube of the bundle, while THF molecules intercalate between the decorated tubes and at the surface of the bundles. In spite of this insertion, the triangular bundle structure is preserved, albeit with a much larger lattice parameter, which depends on the size of the inserted cation.

Cambedouzou, J.; Rols, S.; Bendiab, N.; Almairac, R.; Sauvajol, J.-L.; Petit, P.; Mathis, C.; Mirebeau, I.; Johnson, M. [Laboratoire des Colloiedes, Verres et Nanomateriaux (UMR CNRS 5587), Universite Montpellier II, F-34095 Montpellier Cedex 5 (France); Institut Charles Sadron, 6 rue Boussingault, F-67000 Strasbourg (France); Laboratoire Leon Brillouin, CEA Saclay, F-91191 Gif-sur-Yvette (France); Institut Laue Langevin, F-38042 Grenoble (France)

2005-07-15

92

Single-walled carbon nanotubes with DNA recognition  

NASA Astrophysics Data System (ADS)

Two methods for attaching DNA to oxidized single-walled carbon nanotubes either in organic solvent or aqueous solution are described. The sites of DNA attachment to the nanotubes have been verified by binding gold nanoparticles modified with DNA of complementary sequence to the DNA-modified nanotubes, and imaging with TEM. The gold nanoparticles appear on the tips of the nanotubes, and at isolated positions (defects) on the sidewalls. The methods provide versatility for the modification of nanotubes with DNA for their directed assembly, or for their composites with gold nanoparticles, into nanoscale devices.

Yang, Wenrong; Moghaddam, Minoo J.; Taylor, Sarah; Bojarski, Barbara; Wieczorek, Lech; Herrmann, Jan; McCall, Maxine J.

2007-08-01

93

single-walled carbon nanotube, In-situ Raman scattering and temperature measurements during growth of single-walled  

E-print Network

1. single-walled carbon nanotube, SWNT CVD CVD 2. AFM 1 1 AFM AFM CVD 2 AFM CVD In-situ Raman scattering and temperature measurements during growth of single. of Mech. Eng., The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 Catalytic CVD generation

Maruyama, Shigeo

94

Hexahapto-lanthanide interconnects between the conjugated surfaces of single-walled carbon nanotubes.  

PubMed

We report the response of the electrical conductivity of semiconducting single-walled carbon nanotube (SWNT) thin films on exposure to metal vapors of the early lanthanides under high vacuum conditions. We attribute the strongly enhanced conductivities observed on deposition of samarium and europium to charge transfer from the metals to the SWNT backbone, thereby leading to the first examples of mixed covalent-ionic bis-hexahapto bonds [(?(6)-SWNT)M(?(6)-SWNT), where M = Sm, Eu]. PMID:24553843

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

2014-05-28

95

Scanning gate imaging of two coupled quantum dots in single-walled carbon nanotubes.  

PubMed

Two coupled single wall carbon nanotube quantum dots in a multiple quantum dot system were characterized by using a low temperature scanning gate microscopy (SGM) technique, at a temperature of 170 mK. The locations of single wall carbon nanotube quantum dots were identified by taking the conductance images of a single wall carbon nanotube contacted by two metallic electrodes. The single electron transport through single wall carbon nanotube multiple quantum dots has been observed by varying either the position or voltage bias of a conductive atomic force microscopy tip. Clear hexagonal patterns were observed in the region of the conductance images where only two sets of overlapping conductance rings are visible. The values of coupling capacitance over the total capacitance of the two dots, [Formula: see text] have been extracted to be 0.21 ? 0.27 and 0.23 ? 0.28, respectively. In addition, the interdot coupling (conductance peak splitting) has also been confirmed in both conductance image measurement and current-voltage curves. The results show that a SGM technique enables spectroscopic investigation of coupled quantum dots even in the presence of unexpected multiple quantum dots. PMID:25412585

Zhou, Xin; Hedberg, James; Miyahara, Yoichi; Grutter, Peter; Ishibashi, Koji

2014-12-12

96

Mechanical Properties of Pressure Quenched Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Single wall carbon nanotube (SWNT) samples were compressed in a diamond anvil cell to 36 GPa and studied by in-situ x-ray diffraction at a synchrotron source and by Raman spectroscopy. The samples were quenched from high pressure and nanoindentation studies of the recovered material were performed. Raman studies on the quenched sample show retention of the original features with an additional broad band at 1332 cm-1. Nanoindentation hardness values of the pressure quenched SWNT sample show a value of 0.11 +- 0.4 GPa. This value compares with the pressure quenched hexagonal graphite of 0.14 +- 0.07 GPa and is lower than the hard carbon phase of 30 +- 6 GPa produced by pressure quenching C70-fullerene. The unusual compressibility features of SWNT will be discussed. supported by National Science Foundation (NSF) Grant No. DMR-9704428.

Patterson, Jeremy; Vohra, Yogesh

2001-03-01

97

Translocation events in a single walled carbon nanotube.  

PubMed

Translocation of DNA oligomers through a single walled carbon nanotube was demonstrated recently. Translocation events are accompanied by giant current pulses, the origin of which remains obscure. Here, we show that introduction of a nucleotide alone, guanosine triphosphate into the input reservoir of a carbon nanotube nanofluidic also gives giant current pulses. Taken together with data on oligomer translocation, theses new results suggest that pulse width has a non-linear, power-law dependence on the number of nucleotides in a DNA molecule. We have also measured the time for the onset of DNA translocation pulses after bias reversal, finding that the time for the onset of translocation is directly proportional to the period of bias reversal. PMID:21179393

He, Jin; Liu, Hao; Pang, Pei; Cao, Di; Lindsay, Stuart

2010-11-17

98

Translocation events in a single-walled carbon nanotube  

NASA Astrophysics Data System (ADS)

Translocation of DNA oligomers through a single-walled carbon nanotube was demonstrated recently. Translocation events are accompanied by giant current pulses, the origin of which remains obscure. Here, we show that the introduction of a nucleotide, guanosine triphosphate, alone into the input reservoir of a carbon nanotube nanofluidic device also gives giant current pulses. Taken together with data on oligomer translocation, these new results suggest that the pulse width has a nonlinear, power-law dependence on the number of nucleotides in a DNA molecule. We have also measured the time for the onset of DNA translocation pulses after bias reversal, finding that the time for the onset of translocation is directly proportional to the period of the bias reversal.

He, Jin; Liu, Hao; Pang, Pei; Cao, Di; Lindsay, Stuart

2010-11-01

99

Structural anisotropy of magnetically aligned single wall carbon nanotube films  

SciTech Connect

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.

Smith, B. W. [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Benes, Z. [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Luzzi, D. E. [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Fischer, J. E. [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Walters, D. A. [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)] [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States); Casavant, M. J. [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)] [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States); Schmidt, J. [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)] [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States); Smalley, R. E. [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)] [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)

2000-07-31

100

Selective bundling of zigzag single-walled carbon nanotubes.  

PubMed

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

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

2011-04-26

101

Vertical semiconducting single-walled carbon nanotube Schottky diode  

NASA Astrophysics Data System (ADS)

This paper presents a vertical semiconducting single-walled carbon nanotube (sSWCNT)-based Schottky device. For the first time, the author successfully demonstrated a vertical s-SWCNT Schottky diode on an anodized aluminum oxide (AAO) template. In the vertical pores of an AAO template s-SWCNTs were vertically grown and aligned. The vertical growth of s-SWCNTs inside the pores was achieved by successfully isolating the catalyst at the bottom of the pores by using redeposition enabled angled ion milling. The ends of the grown s-SWCNTs were coated with palladium and titanium to form Schottky and Ohmic contacts, respectively. The I-V characteristics of the vertical s-SWCNT paths engaging the Schottky and Ohmic contacts well demonstrated Schottky diode rectification.

Jung, Sunghwan

2014-07-01

102

Printable thin film supercapacitors using single-walled carbon nanotubes.  

PubMed

Thin film supercapacitors were fabricated using printable materials to make flexible devices on plastic. The active electrodes were made from sprayed networks of single-walled carbon nanotubes (SWCNTs) serving as both electrodes and charge collectors. Using a printable aqueous gel electrolyte as well as an organic liquid electrolyte, the performances of the devices show very high energy and power densities (6 W h/kg for both electrolytes and 23 and 70 kW/kg for aqueous gel electrolyte and organic electrolyte, respectively) which is comparable to performance in other SWCNT-based supercapacitor devices fabricated using different methods. The results underline the potential of printable thin film supercapacitors. The simplified architecture and the sole use of printable materials may lead to a new class of entirely printable charge storage devices allowing for full integration with the emerging field of printed electronics. PMID:19348455

Kaempgen, Martti; Chan, Candace K; Ma, J; Cui, Yi; Gruner, George

2009-05-01

103

Radiation Protection Using Single-Wall Carbon Nanotube Derivatives  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

104

Single-walled carbon nanotube buckypaper and mesophase pitch carbon\\/carbon composites  

Microsoft Academic Search

Carbon\\/carbon composites consisting of single-walled carbon nanotube (SWCNT) buckypaper (BP) and mesophase pitch resin have been produced through impregnation of BP with pitch using toluene as a solvent. Drying, stabilization and carbonization processes were performed sequentially, and repeated to increase the pitch content. Voids in the carbon\\/carbon composite samples decreased with increasing impregnation process cycles. Electrical conductivity and density of

Jin Gyu Park; Nam Gyun Yun; Young Bin Park; Richard Liang; Lloyd Lumata; James S. Brooks; Chuck Zhang; Ben Wang

2010-01-01

105

Single-walled carbon nanotube buckypaper and mesophase pitch carbon\\/carbon composites  

Microsoft Academic Search

Carbon\\/carbon composites consisting of single-walled carbon nanotube (SWCNT) buckypaper (BP) and mesophase pitch resin have been produced through impregnation of BP with pitch using toluene as a solvent. Drying, stabilization and carbonization processes were performed sequentially, and repeated to increase the pitch content. Voids in the carbon\\/carbon composite samples decreased with increasing impregnation process cycles. Electrical conductivity and density of

Jin Gyu Park; Nam Gyun Yun; Young Bin Park; Richard Liang; Lloyd Lumata; James Brooks; Chuck Zhang; Ben Wang

2011-01-01

106

Controlled fabrication of single-walled carbon nanotube electrodes by electron-beam-induced oxidation  

Microsoft Academic Search

The fabrication of metallic single-walled carbon nanotube electrodes separated by gaps of typically 20 nm width by electron-beam-induced oxidation is studied within an active device configuration. The tube conductance is measured continuously during the process. The experiment provides a statistical evaluation of gap sizes as well as the electron dose needed for gap formation. Also, the ability to precisely cut

Cornelius Thiele; Michael Engel; Frank Hennrich; Manfred M. Kappes; Klaus-Peter Johnsen; Carl G. Frase; Hilbert V. Löhneysen; Ralph Krupke

2011-01-01

107

Electronic structure of Eu atomic wires encapsulated inside single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

X-ray absorption (resonant) photoelectron spectroscopy has been employed to investigate electronic structure of Eu atomic wires encapsulated in single-wall carbon nanotubes (SWCNTs). The measurements reveal that there is a substantial electron transfer of +1.79 ± 0.11 from a Eu atom to the surrounding SWCNT. The shape of the observed Fermi edge is different from that of a three-dimensional metal, suggesting that electrons in this one-dimensional system form a Tomonaga-Luttinger liquid.

Nakanishi, Ryo; Kitaura, Ryo; Ayala, Paola; Shiozawa, Hidetsugu; de Blauwe, Kathrin; Hoffmann, Patrick; Choi, Daeheon; Miyata, Yasumitsu; Pichler, Thomas; Shinohara, Hisanori

2012-09-01

108

Single walled carbon nanotubes: Suspension in aqueous/surfactant media and chirality controlled synthesis on surfaces.  

E-print Network

??Single walled carbon nanotube (SWNT) researchers have many obstacles to overcome before SWNTs become commercially applicable including two equally important but separate issues: suspending pristine,… (more)

Moore, Valerie C.

2005-01-01

109

Sensory Arrays of Covalently Functionalized Single-Walled Carbon Nanotubes for Explosive Detection  

E-print Network

Chemiresistive sensor arrays for cyclohexanone and nitromethane are fabricated using single-walled carbon nanotubes (SWCNTs) that are covalently functionalized with urea, thiourea, and squaramide containing selector units. ...

van der Zwaag, Daan

110

Optical properties of single-walled carbon nanotube aerogels  

NASA Astrophysics Data System (ADS)

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

Ostojic, Gordana

2012-02-01

111

Nitrogen-Incorporated Single-Walled Carbon Nanotubes for Devices Shigeo Maruyama1*  

E-print Network

Nitrogen-Incorporated Single-Walled Carbon Nanotubes for Devices Shigeo Maruyama1* ,Theerapol, New York, 14260-1660 U.S.A. maruyama@photon.t.u-tokyo.ac.jp We synthesized single-walled carbon. Einarsson, S. Maruyama, Carbon 50 (2012) 2635. [2] T. Thurakitseree, C. Kramberger, P. Zhao, S. Chiashi, E

Maruyama, Shigeo

112

Anomalous thermal conduction characteristics of phase change composites with single walled carbon nanotube inclusions  

E-print Network

allotropes. The G-band observed at 1594 cm-1 is a characteristic feature of sp2 -bonded graphitic carbonAnomalous thermal conduction characteristics of phase change composites with single walled carbon alkanes in liquid and solid state with single walled carbon nanotube (SWCNT) inclusions. Well

Maruyama, Shigeo

113

Thermal conductivity enhancement of liquid and solid with single-walled carbon nanotubes  

E-print Network

with spherical, one-dimensional and two dimensional carbon allotropes is carried out in this present researchThermal conductivity enhancement of liquid and solid with single-walled carbon nanotubes (CNT) #12;#12;Thermal conductivity enhancement of liquid and solid with single-walled carbon nanotubes (CNT

Maruyama, Shigeo

114

Localized modes in capped single-walled carbon nanotubes Alexander V. Savin1,2,a  

E-print Network

experimentally.9 The growing interest in carbon nano- tubes can be explained by their unique physical properties consider four types of single-walled carbon nano- tubes SWCNs , which are known to have the smallestLocalized modes in capped single-walled carbon nanotubes Alexander V. Savin1,2,a and Yuri S

115

CVD growth mechanism of single-walled carbon nanotubes from alcohol  

E-print Network

CVD growth mechanism of single-walled carbon nanotubes from alcohol Shigeo Maruyama, Yuhei Miyauchi@photon.t.u-tokyo.ac.jp By using alcohol as carbon source, high-purity single-walled carbon nanotubes (SWNTs) can be generated at relatively low CVD temperatures. Based on these findings, we have proposed the alcohol catalytic CVD (ACCVD

Maruyama, Shigeo

116

High temperature rearrangement of disordered nanoporous carbon at the interface with single wall carbon nanotubes  

Microsoft Academic Search

Composites of nanoporous carbon and single wall carbon nanotubes were heat treated in vacuum at temperatures ranging from 1200 to 2000°C. The resultant interface between the two allotropes of carbon was characterized using high resolution transmission electron microscopy and Raman spectroscopy. At the interface between the nanoporous carbon and the nanotube, the nanotube served as a template for ordering and

Bo Yi; Ramakrishnan Rajagopalan; Christopher L. Burket; Henry C. Foley; Xiaoming Liu; Peter C. Eklund

2009-01-01

117

"Smart Skin" optical strain sensor using single wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

Strain measurements are essential in structural health monitoring. Traditional strain gages require physical contact between the sensor and read-out device, perturb the surface being monitored, and allow measurement only at the specific location and orientation axis of the sensor. We demonstrate a novel non-contact, multi- point, multi-directional strain sensing approach that overcomes these limitations. In our method, the surface is coated with a thin film of "smart skin" containing individualized single-walled carbon nanotubes in a polymeric host. After curing, substrate strains are transmitted through the polymer film to embedded nanotubes. This induces axial strains in the nanotubes, systematically shifting the wavelengths of their characteristic near-infrared fluorescence peaks. To measure strain, a visible laser excites nanotubes at points of interest on the surface, and the near-infrared emission is collected and spectrally analyzed. Observed spectral shifts reveal quantitative strain values. Laboratory tests show sensitivity down to ~400µm, limited by mechanical properties of the polymeric host film. We also vary excitation beam polarization to find the axis of substrate strain. Our method provides spatial resolution down to its gage length of ~100µm. Because the entire substrate is coated with nanoscale strain sensors, measurements can be made at arbitrary locations to construct a full strain map. We will describe recent smart skin refinements involving selection of polymer host, nanotube surfactant, nanotube dispersion method, and preparation protocol. Finally, we characterize the orientational distribution of nanotubes using a probabilistic model.

Sun, Peng; Kim, Ji-Hoon; Bachilo, Sergei M.; Weisman, R. Bruce; Nagarajaiah, Satish

2014-04-01

118

Biodegradation of Single-Walled Carbon Nanotubes by Eosinophil Peroxidase  

PubMed Central

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

Andon, 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

119

Potassium-Decorated, Single-Wall Carbon Nanotubes.  

NASA Astrophysics Data System (ADS)

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.

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

1997-03-01

120

Transport and localization in single-walled carbon nanotubes  

SciTech Connect

We have measured the electrical transport properties of mats of single-walled carbon nanotubes (SWNT) as a function of applied electric and magnetic fields. We find that at low temperatures the resistance as a function of temperature R(T) follows the Mott variable range hopping (VRH) formula for hopping in three dimensions. Measurement of the electric field dependence of the resistance R(E) allows for the determination of the Bohr radius of a localized state a{approx}650 nm. The magnetoresistance (MR) of SWNT mat samples is large and negative at all temperatures and fields studied, and can be qualitatively described by theories of MR for VRH systems. The Hall coefficient R{sub H} is positive and nearly temperature-independent. The sign of R{sub H} agrees with the sign of the thermopower. The small magnitude of R{sub H} suggests a large carrier density, but may be the result of cancellation of electron and hole terms. {copyright} {ital 1998 American Institute of Physics.}

Fuhrer, M.S.; Varadarajan, U.; Holmes, W.; Richards, P.L.; Delaney, P.; Louie, S.G.; Zettl, A. [Department of Physics, University of California, Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

1998-08-01

121

Coarse-grained potentials of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

122

Observation and Modeling of Single Wall Carbon Nanotube Bend Junctions  

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

123

Macroscopic neat single-wall carbon nanotube fibers  

NASA Astrophysics Data System (ADS)

Measured and predicted properties of individual single wall carbon nanotubes (SWNT) suggest that bulk SWNT materials will exhibit a variety of exceptional properties. Due to the anisotropic nature of SWNTs, fibers are a logical candidate for these objects. The first ever macroscopic fibers, consisting entirely of SWNTs, were successfully produced and characterized. Nanotubes were dissolved at high concentrations (6--10 wt%) in 102% sulfuric acid. The SWNT/sulfuric acid system exhibited unique one-dimensional liquid crystalline phase behavior and interesting rheological characteristics. Fibers were extruded using a wet jet solution-spinning approach into diethyl ether without extensional drawing. Structural analysis showed them to be the highest aligned neat SWNT material produced to-date, with a revealing substructure of coagulated liquid crystalline domains. Additional characterization showed useful electrical and thermal properties and promising mechanical properties. Finally, the Spinning Bob Mixer (SBM), a custom laboratory mixer/extruder, was designed and successfully tested. Various features of the apparatus were demonstrated and shown to be valuable experimental tools for understanding the production of near SWNT fibers. This research has begun the exploration of an interesting and new field of nanotube science by providing a foundation of understanding and enabling future experiments.

Ericson, Lars Martin

2004-11-01

124

STM investigation of single-wall carbon nanotubes at room temperature  

SciTech Connect

We have used scanning tunneling microscope (STM), operated in ambient conditions, to investigate the atomic structure of single walled-carbon nanotubes (SWNT). The microscopic scale images show tubes condensed in ropes as well as tubes which are separated from each other. For a single-wall nanotube rope, the outer portion is composed of highly oriented nanotubes with nearly uniform diameter and chirality. On separated nanotubes, atomically resolved images show variable chirality ranges between 0-30 deg., and variable diameter (1-3 nm ), with no one type dominant. From STM and scanning tunneling spectroscopy (STS) measurements we confirmed the correlation between the structural parameters and the electronic properties, namely the tuning from metallic to semiconducting. We also observed a rectifying behavior correlated with the chiral angle of 25 deg., an important observation for nano-devices application.

Hassanien, A.; Tokumoto, M. [Electrotechanical Laboratory, 1-1-4 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Kumazawa, Y.; Kataura, H.; Maniwa, Y.; Suzuki, S.; Achiba, Y. [Tokyo Metropolitan University, Minami-osawa, Hachi-oji, Tokyo 192-0397 (Japan)

1999-09-30

125

Laser-induced forward transfer of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The objective of this work is the application of laser-induced forward transfer (LIFT) for the fabrication of chemiresistor sensors. The receiver substrate is an array with metal electrodes and the active materials placed by LIFT are single-walled carbon nanotubes (SWCNT). The functionality of such sensors depends on the geometry of the active material onto the metallic electrodes. First the best geometry for the sensing materials and electrodes was determined, including the optimization of the process parameters for printing uniform pixels of SWCNT onto the sensor electrodes. The sensors were characterized in terms of their sensing characteristics, i.e., upon exposure to ammonia, proving the feasibility of LIFT.

Palla-Papavlu, A.; Dinescu, M.; Wokaun, A.; Lippert, T.

2014-10-01

126

Elastomer Filled With Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

Files, Bradley S.; Forest, Craig R.

2004-01-01

127

Effects of single-walled carbon nanotubes on soil microorganisms  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

128

Dispersion of single wall carbon nanotubes by in situ polymerization under sonication  

E-print Network

Dispersion of single wall carbon nanotubes by in situ polymerization under sonication Cheol Park a 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

Ounaies, Zoubeida

129

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

DOEpatents

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.

Biris, Alexandru S.; Li, Zhongrui

2012-11-06

130

Diameter controlled CVD growth of nitrogen-incorporated single-walled carbon nanotubes  

E-print Network

at Buffalo, State University of New York As we synthesized single-walled carbon nanotubes (SWNTs) usingDiameter controlled CVD growth of nitrogen-incorporated single-walled carbon nanotubes Shigeo was reversible upon the sequence of feedstock introduction. By using 15N isotope of acetonitrile, the catalytic

Maruyama, Shigeo

131

Composites of Single-Walled Carbon Nanotubes and Polystyrene: Preparation and Electrical Conductivity  

E-print Network

Composites of Single-Walled Carbon Nanotubes and Polystyrene: Preparation and ElectricalVised Manuscript ReceiVed February 11, 2008 Composites of single-walled carbon nanotubes (SWNT) and polystyrene (PLV). Nanotubes were incorporated into the polystyrene matrix by two methods: (1) evaporation

Resasco, Daniel

132

Role of Catalysts in the Surface Synthesis of Single-Walled Carbon Nanotubes  

E-print Network

Role of Catalysts in the Surface Synthesis of Single-Walled Carbon Nanotubes Weiwei Zhou, Lei Ding the role of catalysts in the surface growth of single-walled carbon nanotubes (SWNTs) by reviewing recent progress in the surface synthesis of SWNTs. Three effects of catalysts on surface synthesis are studied

Liu, Jie

133

Water transport inside a single-walled carbon nanotube driven by temperature gradient  

E-print Network

Water transport inside a single-walled carbon nanotube driven by temperature gradient J. Shiomi mass transport of a water cluster inside a single-walled carbon nanotube (SWNT) with the diameter of about 1.4 nm. The influence of the non-equilibrium thermal environment on the confined water cluster has

Maruyama, Shigeo

134

Grafting of Poly(4-vinylpyridine) to Single-Walled Carbon Nanotubes and Assembly of Multilayer Films  

E-print Network

with polystyrene using similar procedure.20 Now we report the grafting of poly(4-vinylpyridine) (PVP) to SWNTGrafting of Poly(4-vinylpyridine) to Single-Walled Carbon Nanotubes and Assembly of Multilayer Received September 23, 2004 ABSTRACT: Poly(4-vinylpyridine) grafts to single-walled carbon nanotubes (SWNT

Resasco, Daniel

135

Modifying the Electronic Character of Single-Walled Carbon Nanotubes Through Anisotropic Polymer Interaction  

E-print Network

have previously been observed in nano- tube composites.[8,9] SWNTs exhibit different Raman responsesModifying the Electronic Character of Single-Walled Carbon Nanotubes Through Anisotropic Polymer, single-walled carbon nanotube (SWNT)±polymer composites have received much attention due to their im

Harmon, Julie P.

136

Novel Nanotube-on-Insulator (NOI) Approach toward Single-Walled Carbon  

E-print Network

-on-insulator (NOI) approach for fabricating nano- tube devices based on aligned single-walled carbon nanotubes grown include dispersing nanotubes onto prefabricated electrodes, or locating the predispersed nano- tubes usingNovel Nanotube-on-Insulator (NOI) Approach toward Single-Walled Carbon Nanotube Devices Xiaolei Liu

Zhou, Chongwu

137

Valence excitations in individual single-wall carbon nanotubes Thomas Stockli,a),b)  

E-print Network

single-wall carbon nano- tubes are sensitive to electron irradiation we have operated the microscope. In Fig. 2 c the zero loss peak recorded on a zone just beside the nano- tube is shown. This illustratesValence excitations in individual single-wall carbon nanotubes Thomas Sto¨ckli,a),b) Jean

Wang, Zhong L.

138

Computational modeling of thermal conductivity of single walled carbon nanotube polymer composites  

E-print Network

was developed to study the thermal conductivity of single walled carbon nanotube (SWNT)-polymer composites that there was no significant increase in thermal conductivity for the nano-composites with loading up to 5wt%. It increased1 Computational modeling of thermal conductivity of single walled carbon nanotube polymer

Maruyama, Shigeo

139

Isotope-induced elastic scattering of optical phonons in individual suspended single-walled carbon nanotubes  

E-print Network

Isotope-induced elastic scattering of optical phonons in individual suspended single-walled carbon 10, 2011) Isotope-induced scattering of optical phonons in individual single-walled carbon nanotubes (SWNTs) was investigated by resonance Raman scattering measurements of more than 600 sus- pended, isotope

Maruyama, Shigeo

140

From isotope labeled CH3CN to N2 inside single-walled carbon nanotubes  

E-print Network

From isotope labeled CH3CN to N2 inside single-walled carbon nanotubes Christian Kramberger to this peculiar place? We have used N15 and C13 isotope labeled acetonitrile during the synthesis of single-walled carbon nanotubes to investigate this process. The isotope shifts of phonons and vibrons are observed

Maruyama, Shigeo

141

Fluorescence spectroscopy of single-walled carbon nanotubes synthesized from alcohol  

E-print Network

I&EC 221 Fluorescence spectroscopy of single-walled carbon nanotubes synthesized from alcohol fluorescence measurements of single-walled carbon nanotubes (SWNTs) catalytically synthesized from alcohol (Alcohol catalytic CVD method, ACCVD) in various experimental conditions were performed. The chirality

Maruyama, Shigeo

142

Carbon atoms in ethanol do not contribute equally to formation of single-walled carbon nanotubes.  

PubMed

We propose a unique experimental technique in which isotopically labeled ethanol, e.g., 12CH3-13CH2-OH, is used to trace the carbon atoms during the formation of single-walled carbon nanotubes (SWNTs) by chemical vapor deposition (CVD). The proportion of 13C is determined from Raman spectra of the obtained SWNTs, yielding the respective contribution of ethanol's two different carbon atoms to SWNT formation. Surprisingly, the carbon away from the hydroxyl group is preferably incorporated into the SWNT structure, and this preference is significantly affected by growth temperature, presence of secondary catalyst metal species such as Mo, and even by the substrate material. These experiments provide solid evidence confirming that the active carbon source is not limited to products of gas-phase decomposition such as ethylene and acetylene, but ethanol itself is arriving at and reacting with the metal catalyst particles. Furthermore, even the substrate or other catalytically inactive species directly influences the formation of SWNTs, possibly by changing the local environment around the catalyst or even the reaction pathway of SWNT formation. These unexpected effects, which are inaccessible by conventional techniques, paint a clearer picture regarding the decomposition and bond breaking process of the ethanol precursor during the entire CVD process and how this might influence the quality of the obtained SWNTs. PMID:23458323

Xiang, Rong; Hou, Bo; Einarsson, Erik; Zhao, Pei; Harish, Sivasankaran; Morimoto, Kenichi; Miyauchi, Yuhei; Chiashi, Shohei; Tang, Zikang; Maruyama, Shigeo

2013-04-23

143

Single-walled carbon nanotube-silicon nitride composites  

NASA Astrophysics Data System (ADS)

Colloidal processing methods were developed in order to disperse highly concentrated 1.0, 2.0, and 6.0 vol% single-walled carbon nantoube (SWNT)-Si 3N4 aqueous composite suspensions. Interparticle pair potentials were developed between individual Si3N4 particles and SWNT bundles by coating them with cationic surfactant molecules of cetyltrimethylammonium bromide (CTAB). Zeta potential, viscosity, and sedimentation measurements were conducted on SWNTs and Si3N4 particle suspensions in order to optimize the pH and amount of adsorbed CTAB. The composite suspension viscosity was pH sensitive and adjusted accordingly before consolidation into three-dimensional solid parts using a rapid prototyping fabrication method called robocasting. High-density composites were produced using spark plasma sintering and structurally intact SWNTs were directly observed in the final sintered microstructure using scanning electron microscopy and Raman spectroscopy. When processed with SWNTs the highly insulative ceramic became electrically conductive and resulted in increased grindability for the otherwise hard to machine ceramic. The high hardness, fracture toughness and density of Si 3N4 was maintained for the composite due to the detailed development of colloidal processing and sintering methods used during fabrication. In addition, the thermal conductivity of the ceramic was reduced with the incorporation of well-dispersed SWNTs. Indentation load studies on the composites revealed sub-surface chipping and deformation around the indent before radial crack development indicating a degree of damage tolerance over the monolith. Along the wake of the crack SWNTs were also observed bridging the crack therefore showing their potential to act as toughening agents in brittle ceramics.

Corral, Erica Lorrane

144

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

PubMed

The formation of covalent bonds to single-walled carbon nanotube (SWNT) or graphene surfaces usually leads to a decrease in the electrical conductivity and mobility as a result of the structural rehybridization of the functionalized carbon atoms from sp(2) to sp(3). In the present study, we explore the effect of metal deposition on semiconducting (SC-) and metallic (MT-) SWNT thin films in the vicinity of the percolation threshold and we are able to clearly delineate the effects of weak physisorption, ionic chemisorption with charge transfer, and covalent hexahapto (?(6)) chemisorption on these percolating networks. The results support the idea that for those metals capable of forming bis-hexahapto-bonds, the generation of covalent (?(6)-SWNT)M(?(6)-SWNT) interconnects provides a conducting pathway in the SWNT films and establishes the transition metal bis-hexahapto organometallic bond as an electronically conjugating linkage between graphene surfaces. PMID:24893323

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

2014-07-01

145

Sequestration of Single-Walled Carbon Nanotubes in a Polymer  

NASA Technical Reports Server (NTRS)

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 observed to precipitate out of epoxies while the epoxies were being cured. If the side chains of the PmPV molecules were functionalized to make them capable of reacting with the epoxy matrices, it might be possible to make progress toward practical applications. By bonding the side chains of the PmPV molecules to an epoxy matrix, one would form an PmPV conduit between the epoxy matrix and the carbon nanotubes sequestered in the PmPV. This conduit would transfer stresses from the epoxy matrix to the nanotubes. This proposed load-transfer mode is similar to that of the current practice in which silane groups are chemically bonded to both the epoxy matrices and the fibers (often glass fibers) in epoxymatrix/fiber composites.

Bley, Richard A.

2007-01-01

146

Simultaneous Raman scattering and fluorescence on Single wall carbon nanotubes  

Microsoft Academic Search

The simultaneous observation of Raman scattering and fluorescence on the same sample, pioneered by the Weisman group, provides more information than either technique separately. Observation of these phenomena on the same individual single wall nanotube provides a particularly powerful joint probe for the following reason. At the single nanotube level, the Raman effect can be used not only to provide

Adelina Santos; Grace Shin; Georgii Samsonidze; Gene Dresselhaus; Mildred Dresselhaus; Steve Cronin; Antonio Souza; Marcos Pimenta; Anna Swan; Selim Ünlü; Bennett Goldberg

2003-01-01

147

Different techniques for characterizing single-walled carbon nanotube purity  

NASA Astrophysics Data System (ADS)

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

Yuca, Neslihan; Camtakan, Zeyneb; Karatepe, Nilgün

2013-09-01

148

State of the art of single-walled carbon nanotube synthesis on surfaces.  

PubMed

Single-walled carbon nanotubes (SWNTs) directly synthesized on surfaces are promising building blocks for nanoelectronics. The structures and the arrangement of the SWNTs on surfaces determine the quality and density of the fabricated nanoelectronics, implying the importance of structure controlled growth of SWNTs on surfaces. This review summarizes the recent research status in controlling the orientation, length, density, diameter, metallicity, and chirality of SWNTs directly synthesized on surfaces by chemical vapor deposition, together with a session presenting the characterization method of the chirality of SWNTs. Finally, the remaining major challenges are discussed and future research directions are proposed. PMID:25042346

Chen, Yabin; Zhang, Yingying; Hu, Yue; Kang, Lixing; Zhang, Shuchen; Xie, Huanhuan; Liu, Dan; Zhao, Qiuchen; Li, Qingwen; Zhang, Jin

2014-09-10

149

Fast Characterization of Magnetic Impurities in Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

150

Diameter Dependent Magnetic and Electronic Properties of Single-Walled Carbon Nanotubes with Fe Nanowires  

NASA Astrophysics Data System (ADS)

We investigate the electronic and magnetic properties of single-walled carbon nanotubes (SWNTs) filled with Fe nanowires, based on the spin-polarized density functional theory. We find that in the stable structure, the Fe-filled (3,3) and (5,0) SWNTs exhibit semiconducting properties, and the magnetic moment of Fe nanowires inside disappears. On the other hand, the Fe-filled (4,4), (5,5), (6,6) and (6,0) SWNTs, having larger radii, are metallic and exhibit ferromagnetic properties. The corresponding magnetic moment increases with increasing nanotube diameter.

Kisaku, Masanori; Rahman, MD. Mahmudur; Kishi, Tomoya; Matsunaka, Daisuke; Roman, Tanglaw Abat; Diño, Wilson Agerico; Nakanishi, Hiroshi; Kasai, Hideaki

2005-02-01

151

Controlling the doping of single-walled carbon nanotube networks by proton irradiation  

SciTech Connect

We demonstrate the controlled desorption of adventitious dopants on networks of single-walled carbon nanotubes (SWNTs) with 100 keV proton irradiation. Networks of sorted metallic, semiconducting SWNTs, and unsorted SWNTs were investigated. The removal of dopants was indicated by an increase in sheet resistances along with an increase in the absorption of the low energy absorption band of semiconducting SWNTs. Semiconducting and unsorted SWNT networks exhibited the largest change in their sheet resistance, which indicates the conductivity of unsorted SWNT networks is dominated by the tube-tube junctions of semiconducting SWNTs.

Walker, D.; Mann, C. J.; Panetta, C. J.; Alaan, D. R.; Hopkins, A. R.; Liu, S. H. [Physical Sciences Laboratories, Aerospace Corporation, P. O. Box 92957 M2/275, Los Angeles, California 90009-2957 (United States)

2012-09-03

152

Improved temperature characteristics of single-wall carbon nanotube single electron transistors using carboxymethylcellulose dispersant  

NASA Astrophysics Data System (ADS)

Single-wall carbon nanotube (SWNT) based single electron transistors were fabricated by the dispersion method using carboxymethylcellulose (CMC) as a dispersant to make SWNT suspension. The temperature characteristics were improved compared to the one fabricated with a Triton X-100/water SWNT suspension, so that the regular Coulomb oscillations were observed up to 80K. This could be due to the increased barrier height, which may be originated from extra dipoles induced by the adsorbed CMC molecules at the SWNT/metal interface.

Mori, Takahiro; Omura, Kazuo; Sato, Shunsuke; Suzuki, Masaki; Uchida, Katsumi; Yajima, Hirofumi; Ishibashi, Koji

2007-12-01

153

The Use of Single-Wall Carbon Nanotubes as Templates for Organic Molecules  

NASA Astrophysics Data System (ADS)

Single wall carbon nanotubes are insoluble in most organic solvents such as toluene. Improvements in the solubility of the single wall carbon nanotubes are however seen as a result of specific interactions with oligomers such as terphenyl and anthracene. Suspensions formed in toluene with these oligomers and the single wall carbon nanotubes are seen to be stable over prolonged periods. Spectroscopic analysis clearly shows an interaction between the carbon nanotubes and the oligomers. It is proposed in this study that the use of these more simple molecular systems may help elucidate the nature and extent of the interaction in more complex composite based systems.

Hedderman, T. G.; O'Neill, L.; Keogh, S. M.; Gregan, E.; Mc Carthy, B.; Dalton, A. B.; Chambers, G.; Byrne, H. J.

2002-10-01

154

Direct imaging the subcellular localization of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The development of single-walled carbon nanotubes (SWNTs) for various biomedical applications is an area of great promise. However, the contradictory data on the interaction of single-walled carbon nanotubes with cells highlight the need to study their uptake and cytotoxic effects in cells. Here, we use confocal microscopy to image the translocation of single-walled carbon nanotubes into cells and localization on the subcellular organelle. We also observe that single-walled carbon nanotubes do not affect the cellular condition and mitochondrial membrane potential. One intrinsic property of single-walled carbon nanotubes is their strong optical absorbance in the near-infrared (NIR) region. It could be used to selectively increase the thermal destructions in the target tumors. A specific type of SWNT by the CoMoCAT method has an intense absorption band at 980 nm. When irradiated with a 980-nm laser, the single-walled carbon nanotubes affect the cellular oxidation and destroy the mitochondrial membrane potential, and induce cell apoptosis. Thus, the single-walled carbon nanotubes appear to enter the cytoplasm without cytotoxic effects in cells, and can be used as effective and selective nanomaterials for cancer photothermal therapy.

Zhou, Feifan; Xing, Da; Chen, Wei R.

2011-03-01

155

Optical and vibrational properties of single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

Kennedy, W. Joshua

156

Diffusion of single-walled carbon nanotube under physiological conditions.  

PubMed

Single-walled carbon nanotube (SWNT) can be functionalized to target cells for drug delivery or cancer cells for their detection and therapy. Understanding their transport phenomena in vivo is a necessary step to unlock their medical potential. This work estimates the diffusion characteristics of SWNTs and their DNA-conjugated bio-hybrids under simulated or postulated physiological conditions using EPI-fluorescence microscopy (EFM). SWNT was shortened and dispersed in aqueous solution with the average length and diameter of 253 nm (+/-30.6 nm) and 1.6 nm (+/-0.34 nm), respectively, and tagged with a fluorophore, 1-pyrenebutanoic succinimidyl ester (PSE), through non-covalent pi stacking. DNA was attached to the PSE-SWNTs through carboxiimide based coupling procedure. Using the EFM, real-time videos were recorded under four different viscosities corresponding to four kinds of human body fluids: lymph (1.4 cP), bile (2.4 cP), blood (3-6 cP), and cytoplasm (10-30 cP), and processed to calculate diffusion coefficients based on random walk and speed. At 37 degreeC, diffusion coefficients of the SWNTs were estimated to be: 1.45 (+/-0.652) x 10(4) nm2/s (lymph), 0.91 (+/-0.205) x 10(4) nm2/s (bile), 0.59 (+/-0.179)x 10(4) nm2/s (blood), and 0.26 (+/-0.114)x 10(4) nm2/s (cytoplasm). Estimated diffusion coefficients of SWNT-DNA bio-hybrids were: 1.45 (+/-0.402) x 10(4) nm2/s (plasma), 0.62 (+/-0.212) x 10(4) nm2/s (bile), 0.41 (+/-0.142) x 10(4) nm2/s (blood), 0.38 (+/-0.257) x 10(4) nm2/s (cytoplasm). These outcomes should serve as key data for developing mathematical models of SWNT-based drug delivery, cell targeting, and its biodistribution. PMID:23858971

Judkins, John; Lee, Hyun Ho; Tung, Steve; Kim, Jin-Woo

2013-06-01

157

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

158

Single-wall carbon nanotubes as attractive toughening agents in alumina-based nanocomposites  

NASA Astrophysics Data System (ADS)

The extraordinary mechanical, thermal and electrical properties of carbon nanotubes have prompted intense research into a wide range of applications in structural materials, electronics, chemical processing and energy management. Attempts have been made to develop advanced engineering materials with improved or novel properties through the incorporation of carbon nanotubes in selected matrices (polymers, metals and ceramics). But the use of carbon nanotubes to reinforce ceramic composites has not been very successful; for example, in alumina-based systems only a 24% increase in toughness has been obtained so far. Here we demonstrate their potential use in reinforcing nanocrystalline ceramics. We have fabricated fully dense nanocomposites of single-wall carbon nanotubes with nanocrystalline alumina (Al2O3) matrix at sintering temperatures as low as 1,150 °C by spark-plasma sintering. A fracture toughness of 9.7 MPa m½, nearly three times that of pure nanocrystalline alumina, can be achieved.

Zhan, Guo-Dong; Kuntz, Joshua D.; Wan, Julin; Mukherjee, Amiya K.

2003-01-01

159

Single-wall carbon nanotubes as attractive toughening agents in alumina-based nanocomposites.  

PubMed

The extraordinary mechanical, thermal and electrical properties of carbon nanotubes have prompted intense research into a wide range of applications in structural materials, electronics, chemical processing and energy management. Attempts have been made to develop advanced engineering materials with improved or novel properties through the incorporation of carbon nanotubes in selected matrices (polymers, metals and ceramics). But the use of carbon nanotubes to reinforce ceramic composites has not been very successful; for example, in alumina-based systems only a 24% increase in toughness has been obtained so far. Here we demonstrate their potential use in reinforcing nanocrystalline ceramics. We have fabricated fully dense nanocomposites of single-wall carbon nanotubes with nanocrystalline alumina (Al2O3) matrix at sintering temperatures as low as 1,150 degrees C by spark-plasma sintering. A fracture toughness of 9.7 MPa m 1/2, nearly three times that of pure nanocrystalline alumina, can be achieved. PMID:12652671

Zhan, Guo-Dong; Kuntz, Joshua D; Wan, Julin; Mukherjee, Amiya K

2003-01-01

160

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

PubMed Central

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

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

2009-01-01

161

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

PubMed Central

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

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

2013-01-01

162

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

PubMed Central

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 ?m-CMOS RF/DC rectifier chipset and a sensor head of palladium-decorated single walled carbon nanotubes (Pd-SWCNTs) are surface mounted in cascade. The performances of the sensor are examined and described by the defined parameters of the received signal strength index (RSSI) and the comparative analog identifier (?AID). Results validate the sensor's ability to detect molecules of methane at room temperature, showing that the RSSI can increase 4 dB and the ?AID can increase 3% in response to methane concentrations ranging from zero to 100 ppm. PMID:23845931

Liu, Jian; Li, Guomin

2013-01-01

163

Identification of nitrogen dopants in single-walled carbon nanotubes by scanning tunneling microscopy.  

PubMed

Using scanning tunnelling microscopy and spectroscopy, we investigated the atomic and electronic structure of nitrogen-doped single walled carbon nanotubes synthesized by chemical vapor deposition. The insertion of nitrogen in the carbon lattice induces several types of point defects involving different atomic configurations. Spectroscopic measurements on semiconducting nanotubes reveal that these local structures can induce either extended shallow levels or more localized deep levels. In a metallic tube, a single doping site associated with a donor state was observed in the gap at an energy close to that of the first van Hove singularity. Density functional theory calculations reveal that this feature corresponds to a substitutional nitrogen atom in the carbon network. PMID:23829349

Tison, Yann; Lin, Hong; Lagoute, Jérôme; Repain, Vincent; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Henrard, Luc; Zheng, Bing; Susi, Toma; Kauppinen, Esko I; Ducastelle, François; Loiseau, Annick

2013-08-27

164

Peptide Secondary Structure Modulates Single-Walled Carbon Nanotube Fluorescence as a Chaperone Sensor for Nitroaromatics  

E-print Network

A class of peptides from the bombolitin family, not previously identified for nitroaromatic recognition, allows near-infrared fluorescent single-walled carbon nanotubes to transduce specific changes in their conformation. ...

Heller, Daniel Alan

165

Chirality dependence of coherent phonon amplitudes in single-wall carbon nanotubes  

E-print Network

We simulate the ultrafast dynamics of laser-induced coherent phonons in single-wall carbon nanotubes (SWNTs). In particular, we examine the coherent phonon amplitude of the radial breathing mode (RBM) as a function of ...

Dresselhaus, Mildred

166

Ultrafast spectroscopy of single-chirality single-walled carbon nanotubes.  

E-print Network

??Single-walled carbon nanotubes (SWNTs) are quasi-one-dimensional nanomaterials. There are a variety of SWNT structures defined by different diameter and chirality. The most recent progress in… (more)

Wang, Shujing (1982 - )

2010-01-01

167

Robust Cyclohexanone Selective Chemiresistors Based on Single-Walled Carbon Nanotubes  

E-print Network

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 ...

Frazier, Kelvin Mitchell

168

Theoretical and simulation tools for electron transfer and chain reactions in single walled carbon nanotubes  

E-print Network

Single walled carbon nanotubes (SWNT) are cylindrical sheets of graphene whose electronic structures and diameters are determined by their chiralities. Current synthetic methods produce batches of nanotubes containing a ...

Nair, Nitish

2009-01-01

169

Fermi-Energy-Dependent Structural Deformation of Chiral Single-Wall Carbon Nanotubes  

E-print Network

In this work, we use an extended tight-binding approach for calculating the Fermi-energy dependence of the structural deformation of chiral single-wall carbon nanotubes (SWNTs). We show that, in general, nanotube strains ...

Vieira, Bruno G.?M.

170

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

PubMed

Herein, we studied the binding interactions between hydroxylated single-walled carbon nanotubes and hemoglobin and myoglobin by the use of multi-spectral techniques and molecular modeling. The ultraviolet-vis absorbance and circular dichroism spectral results indicated that the binding interactions existed between hydroxylated single-walled carbon nanotubes and hemoglobin/myoglobin. These binding interactions partially affected the soret/heme bands of hemoglobin and myoglobin. The secondary structures of hemoproteins were partially destroyed by hydroxylated single-walled carbon nanotubes. Fluorescence studies suggested that the complexes formed between hydroxylated single-walled carbon nanotubes and hemoglobin/myoglobin by hydrogen bonding, hydrophobic, and ?-? stacking interactions. In addition, molecular modeling analysis well supported the experimental results. PMID:25313539

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

2014-12-01

171

Catalytic CVD Synthesis of Single-Walled Carbon Nanotubes from Alcohol  

E-print Network

Catalytic CVD Synthesis of Single-Walled Carbon Nanotubes from Alcohol S. Maruyama Department-temperature feature of alcohol CCVD method. With a simple dip-coat method, this technique first produced SWNTs

Maruyama, Shigeo

172

High Weight Fraction Surfactant Solubilization of Single-Wall Carbon Nanotubes in Water  

Microsoft Academic Search

We report a simple process to solubilize high weight fraction single-wall carbon nanotubes in water by the nonspecific physical adsorption of sodium dodecylbenzene sulfonate. The diameter distribution of nanotubes in the dispersion, measured by atomic force microscopy, showed that even at 20 mg\\/mL 63 ± 5% of single-wall carbon nanotube bundles exfoliated into single tubes. A measure of the length

M. F. Islam; E. Rojas; D. M. Bergey; A. T. Johnson; A. G. Yodh

2003-01-01

173

Optical Signatures of the Aharonov-Bohm Phase in Single-Walled Carbon Nanotubes  

Microsoft Academic Search

We report interband magneto-optical spectra for single-walled carbon nanotubes in high magnetic fields up to 45 tesla, confirming theoretical predictions that the band structure of a single-walled carbon nanotube is dependent on the magnetic flux phi threading the tube. We have observed field-induced optical anisotropy as well as red shifts and splittings of absorption and photoluminescence peaks. The amounts of

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

2004-01-01

174

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

NASA Astrophysics Data System (ADS)

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 phonons from the boron nitride on the electrical properties of the carbon nanotube. Finally a few research projects are discussed in which carbon nanotubes of known chirality were used in conjunction with first electrical tests on molecules, secondly on a prefabricated complementary metal-oxide-semiconductor integrated circuit as an inverter and lastly to study the photoconductivity generated by a synchrotron laser source to identify the values for the low energy excitonic peak.

Caldwell, Robert Victor

175

Lithium intercalation into single-walled carbon nanotubes network electrode: Storage mechanisms and impurity effects  

NASA Astrophysics Data System (ADS)

This is a detailed study of how impurities can affect the mechanisms of lithium storage in composite electrodes consisting of a three-dimensional single-walled carbon nanotube (SWCNT) bundles network. To remove impurities such as fullerenes, amorphous carbon, catalyst, and nanographite, we submitted the SWCNT bundles to an appropriate chemical treatment before using them to prepare the electrode. Then, we analyzed how this treatment influenced electrode potential, fading capacity, and specific capacity. Additionally, we evaluated the electrode prepared with high-purity SWNCT bundles by galvanostatic intermittent titration, to obtain lithium transport parameters under thermodynamic conditions. We achieved an intrinsic specific capacity of 400 mAh g-1 for the purified SWCNT bundles prepared by an arc-reactor method. The transport parameters revealed that the electrode underwent electronic transition of the semiconducting-metal type. The chemical diffusion coefficient ranged from 10-4 to 10-18 cm2 s-1 with decreasing electrode potential.

Montoro, Luciano Andrey; Matsubara, Elaine Yoshiko; Rosolen, José Maurício

2014-07-01

176

Patterning of single walled carbon nanotubes using a low-fluence excimer laser photoablation process  

E-print Network

, as the ablation assistor and it was coated on the carbon nano- tube layer, as shown in Fig. 1 b . The photoresist deposition process causes the resist to be placed under the carbon nano- tubes as well as on topPatterning of single walled carbon nanotubes using a low-fluence excimer laser photoablation

Rogers, John A.

177

Importance of carbon solubility and wetting properties of nickel nanoparticles for single wall nanotube growth  

E-print Network

Importance of carbon solubility and wetting properties of nickel nanoparticles for single wall, a typical catalyst, and show that carbon solubility increases for smaller nanoparticles that are either that wetting properties of the nanoparticles, controlled by carbon solubility, are of fundamental importance

Paris-Sud XI, Université de

178

Heteroepitaxial Growth of Single-Walled Carbon Nanotubes from Boron Nitride  

PubMed Central

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

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

179

Single-walled carbon nanotubes/hydroxyapatite coatings on titanium obtained by electrochemical deposition  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes/hydroxyapatite (SWNTs/HA) composite coatings were successfully fabricated by electrochemical deposition technique. Different concentrations of SWNTs were incorporated into the apatite coating by adding functionalized SWNTs into the electrolyte. Homogeneous and crack-free SWNTs/HA composite coatings were achieved and the coatings had higher crystallinity compared to pure HA coating. In addition, the highest bonding strength of the SWNTs/HA coating reached 25.7 MPa, which was nearly 70% higher than that of pure HA coating. The in-vitro cellular biocompatibility tests revealed that SWNTs/HA composite coatings exhibited higher in-vitro bioactivity than that of pure HA coating and pure titanium (Ti). It suggests that SWNTs/HA composite coating may have enormous potential applications in the field of biomaterials, especially for the metal implants.

Pei, Xibo; Zeng, Yongxiang; He, Rui; Li, Zhongjie; Tian, Lingyang; Wang, Jian; Wan, Qianbing; Li, Xiaoyu; Bao, Hong

2014-03-01

180

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

PubMed

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

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

2013-01-01

181

Liquid as a required catalyst phase for carbon single-walled nanotube growth  

NASA Astrophysics Data System (ADS)

The evolution of the iron catalyst during carbon single-walled nanotube growth is studied using calorimetry, temperature-programmed oxidation and Raman measurements. Carbon-induced solid-liquid, and solid-liquid-solid phase transitions of the nanocatalyst during the synthesis were observed. We found that liquid phase is favored for the growth of nanotubes, while the solidification of the catalyst nearly terminates the growth. No growth was observed below the eutectic point, when the catalyst is in solid phase. Our results support a growth mechanism of single-walled carbon nanotubes on liquid catalyst particles.

Harutyunyan, A. R.; Tokune, T.; Mora, E.

2005-08-01

182

Amphoteric doping of single-wall carbon-nanotube thin films as probed by optical absorption spectroscopy  

Microsoft Academic Search

We have separately probed the doping behavior of semiconducting (S) and metallic (M) single-wall carbon-nanotube (SWNT) films, by optical absorption and dc resistance (R) measurements. Either electron acceptors (Br2, I2) or donors (K, Cs) were used as dopants with controlled stoichiometry. Disappearance of absorption bands at 0.68, 1.2, and 1.8 eV, and concomitant decrease of R by doping have been

S. Kazaoui; N. Minami; R. Jacquemin; H. Kataura; Y. Achiba

1999-01-01

183

Iijima Ichihashi (1) (single-walled carbon nanotubes, SWNTs)  

E-print Network

CVD (chemical vapor deposition) SWNTs SWNTs CVD Fe(CO)5 HiPco (high pressure carbon monoxide) (3) CVD (alcohol catalytic chemical vapor deposition, ACCVD) (4) CoMoCAT (cobalt-molybdenum catalysts) (5) SWNTs SWNTs ACCVD (6) SWNTs (7) (8) CVD *1 *2 SWNT Synthesis by Carbon

Maruyama, Shigeo

184

Effects of temperature and torsion speed on torsional properties of single-walled carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes (CNTs) are excellent candidates for torsional elements used in nanoelectro-mechanical systems (NEMS). Simulations show that after being twisted to a certain angle, they buckle and lose their mechanical strength. In this paper, classical molecular dynamics simulations are performed on single-walled carbon nanotubes (CNTs) to investigate the effects of torsion speed and temperature on CNT torsional properties. The AIREBO

A. R. Khoei; E. Ban; P. Banihashemi; M. J. Abdolhosseini Qomi

2011-01-01

185

Synthesis and characterization of single-wall carbon nanotubeamorphous diamond thin-film composites  

E-print Network

Synthesis and characterization of single-wall carbon nanotube­amorphous diamond thin-film in an optically transmissive, all-carbon thin-film composite. © 2002 American Institute of Physics. DOI: 10 deposition PLD , a versatile method for thin-film synthesis is explored to en- capsulate SWNT in a thin-film

Geohegan, David B.

186

Packing-induced electronic structure changes in bundled single-wall carbon nanotubes  

E-print Network

of carbon hexagons and their matching around the tube's circumference,12­15 the distortion of the straight of parallel and braided nano- tubes. These observations unambiguousPacking-induced electronic structure changes in bundled single-wall carbon nanotubes P. Castrucci

187

Raman probing of uniaxial strain in individual single-wall carbon nanotubes in a composite  

E-print Network

Raman probing of uniaxial strain in individual single-wall carbon nanotubes in a composite material in nano optoelectronic devices as transistors and diodes3 or as nano emitter of light.4 Because carbon1040635 #12;Abstract The temperature dependence of the Raman spectrum of a gelatine-based composite mate

Paris-Sud XI, Université de

188

Floated Catalyst CVD Generation of Single-Walled Carbon Nanotubes from Alcohol  

E-print Network

Floated Catalyst CVD Generation of Single-Walled Carbon Nanotubes from Alcohol Shigeo Maruyama technique of SWNTs from alcohol. By using alcohol as a carbon source, high-purity SWNTs were produced at relatively low temperature (550-900 $^o$C), probably because oxygen atoms contained in alcohol molecules

Maruyama, Shigeo

189

High-Purity Catalytic CVD Generation of Single-Walled Carbon Nanotubes from Alcohol  

E-print Network

High-Purity Catalytic CVD Generation of Single-Walled Carbon Nanotubes from Alcohol Shigeo Maruyama alcohols are much better carbon sources for SWNTs than hydrocarbons is explained by the role of decomposed OH radicals as follows. Since an OH radical is decomposed on the catalyst surface from an alcohol

Maruyama, Shigeo

190

VERTICALLY ALIGNED CARPET OF SINGLE-WALLED CARBON NANOTUBES CATALYTICALLY GROWN FROM ALCOHOL  

E-print Network

VERTICALLY ALIGNED CARPET OF SINGLE-WALLED CARBON NANOTUBES CATALYTICALLY GROWN FROM ALCOHOL Shigeo alcohol as the carbon source are discussed. High-purity SWNTs can be generated at relatively low CVD ethanol (alcohol catalytic chemical vapor deposition, ACCVD) is performed by using densely mono

Maruyama, Shigeo

191

Single Crystals of Single-Walled Carbon Nanotubes Formed by  

E-print Network

for nanoscale manipulation (13) has substantial future technological potential. One of the most desirable aims). For both methods, the addition of a small quan- tity of metal catalyst (Co, Ni, Fe, or Mo) increases

Gimzewski, James

192

Achieving ultrahigh concentrations of fluorescent single-walled carbon nanotubes using small-molecule viscosity modifiers.  

PubMed

Surfactant dispersion is a well-established method for stabilizing individual single-walled carbon nanotubes in aqueous solutions. However, achieving high concentrations of individually dispersed nanotubes with this technique has proven challenging. Here it is demonstrated that the introduction of viscosity-enhancing compounds such as sucrose can increase the maximum concentration of surfactant-dispersed single-walled carbon nanotubes by more than a factor of 100 while still retaining the optical properties of individual nanotubes. When these solutions are used as inks for methods such as inkjet printing, they retain their fluorescent properties even after the ink has dried. PMID:22930552

Leeds, Jarrett D; Fourkas, John T; Wang, Yuhuang

2013-01-28

193

Lithium Doping of Single-Walled Carbon Nanotubes for Battery and Semiconductor Applications Kevin Donaher, Columbia University, Georgia Institute of Technology SURF 2010 Fellow  

E-print Network

Lithium Doping of Single-Walled Carbon Nanotubes for Battery and Semiconductor Applications Kevin Jang, Mentor: Wonsang Koh Abstract The properties of lithium doped (5,5) metallic and (8 lithium binds to carbon nanotubes and how this affects the band structure of the semiconducting carbon

Li, Mo

194

Laser synthesis of single-wall carbon nanotubes with time-resolved in-situ diagnostics  

NASA Astrophysics Data System (ADS)

Laser vaporization (LV) is a remarkably versatile technique for the catalytically-aided synthesis of nanomaterials, such as single-wall carbon nanotubes (SWNT). SWNT show remarkable promise for future generations of electronics and structural materials, however their application and commercialization has been hampered by a lack of control over the synthesis process, and low production quantities. Time-resolved in situ spectroscopic investigations of the laser-vaporization SWNT-synthesis process are described which are yielding some of the first direct determinations of carbon nanotube growth mechanisms and rates necessary to evaluate strategies for controllable synthesis and large- scale production. Our measurements indicate that SWNT grow over extended annealing times during the LV process by the conversion of condensed phase nanoparticle feedstock. These measurements were extended to grow carbon nanotubes by CO2-laser-annealing heat treatments of carbon and metal nanoparticle mixtures, offering an alternative synthesis approach to vapor-phase methods. These results present opportunities for scaled-up production of nanomaterials compatible with commercial high-power laser technology.

Geohegan, David B.; Puretzky, Alexander A.; Schittenhelm, Henrik; Fan, Xudong; Britt, Philip F.; Guillorn, Michael A.; Simpson, Michael L.; Merkulov, Vladimir I.; Austin, Derek W.; Pennycook, Stephen J.; Joy, David C.

2002-03-01

195

Laser synthesis of single-wall carbon nanotubes with time-resolved in situ diagnostics  

NASA Astrophysics Data System (ADS)

Laser vaporization (LV) is a remarkably versatile technique for the catalytically-aided synthesis of nanomaterials, such as single-wall carbon nanotubes (SWNT). SWNT show remarkable promise for future generations of electronics and structural materials, however their application and commercialization has been hampered by a lack of control over the synthesis process, and low production quantities. Time-resolved in situ spectroscopic investigations of the laser-vaporization SWNT-synthesis process are described which are yielding some of the first direction determinations of carbon nanotube growth mechanisms and rates necessary to evaluate strategies for controllable synthesis and large-scale production. Our measurements indicate that SWNT grow over extended annealing times during the LV process by the conversion of condensed phase nanoparticle feedstock. These measurements were extended to grow carbon nanotubes by CO2- laser-annealing heat treatments of carbon and metal nanoparticle mixtures, offering an alternative synthesis approach to vapor- phase methods. These results present opportunities for scaled-up production of nanomaterials compatible with commercial high- power-laser technology.

Geohegan, David B.; Puretzky, Alexander A.; Schittenhelm, Henrik; Fan, Xudong; Britt, Philip F.; Guillorn, Michael A.; Simpson, Michael L.; Merkulov, Vladimir I.; Austin, Derek W.; Pennycook, Stephen J.; Joy, David C.

2002-08-01

196

Gas detection mechanism for single-walled carbon nanotube networks  

NASA Astrophysics Data System (ADS)

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 [1]. 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. [4pt] [1] J. Zhang, A. Boyd, A. Tselev, M. Paranjape, and P. Barbara, Mechanism of NO2 detection in carbon nanotube field effect transistor chemical sensors, Applied Physics Letters 88, 123112-123115 (2006)

Boyd, Anthony; Dube, Isha; Fedorov, Georgy; Paranjape, Makarand; Barbara, Paola

2011-03-01

197

High Purity and Low-Temperature Generation of Single-Walled Carbon Nanotubes by a Catalytic CVD Method  

E-print Network

chemical vapor deposition technique to generate high-purity single walled carbon nanotubes (SWNTs) is demonstrated. Pure SWNTs without amorphous carbon coating, multi-walled carbon nanotubes, carbon nanoparticles

Maruyama, Shigeo

198

Thermal Properties of Metal-Coated Vertically Aligned Single-Wall Nanotube Arrays  

Microsoft Academic Search

Owing to their high thermal conductivities, carbon nanotubes (CNTs) are promising for use in advanced thermal interface materials. While there has been much previous re- search on the properties of isolated CNTs, there are few thermal data for aligned films of single wall nanotubes. Furthermore, such data for nanotube films do not separate volume from interface thermal resistances. This paper

M. A. Panzer; G. Zhang; D. Mann; X. Hu; E. Pop; H. Dai; K. E. Goodson

2008-01-01

199

Amino acid adsorption on single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigate and discuss the adsorption of a few amino acids on (3,3) carbon nanotubes and on graphite sheets through calculations within density functional theory. Results show weak binding of the biomolecules on both substrates, but through generally favourable adsorption pathways. Zwitterion adsorption through the charged amine and carboxylate groups are bound stronger to the nanotube surface in comparison to their nonionic counterparts, as well as on histidine, phenylalanine, and cysteine side chain groups fixed in specific orientations. Binding strengths on graphite suggest dissimilar trends for amino acid interactions with increasing nanotube diameter.

Roman, T.; Diño, W. A.; Nakanishi, H.; Kasai, H.

2006-04-01

200

Computational Study of Catalyzed Growth of Single Wall Carbon Nanotubes  

E-print Network

is the cap structure. 8 According to the isolated pentagon rule (IPR), no neighbored pentagons should exist in the cap in order to have reasonably stable structure and such caps that follow the isolated pentagon rule are called IPR caps. A certain cap can... of the five-membered rings in the cap and such behavior is explained by the Pentagon-Proximity model. 22 1.4 Application of carbon nanotubes The large aspect ratio, small diameter, low density, high strength and flexibility, and novel electronic...

Zhao, Jin

2010-01-14

201

Effect of Mild Nitric Acid Oxidation on Dispersability, Size, and Structure of Single-Walled Carbon Nanotubes  

E-print Network

on their intended use. Introduction Oxidation of carbon nanotubes is a basic technique for their chemicalEffect of Mild Nitric Acid Oxidation on Dispersability, Size, and Structure of Single-Walled Carbon, 2007. ReVised Manuscript ReceiVed August 29, 2007 Oxidation of single-walled carbon nanotubes (SWNTs

Resasco, Daniel

202

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

PubMed

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

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

2014-02-12

203

Racemic Single-Walled Carbon Nanotubes Exhibit Circular Dichroism When Wrapped with DNA  

E-print Network

Racemic Single-Walled Carbon Nanotubes Exhibit Circular Dichroism When Wrapped with DNA Gordana for solubilization of SWNTs in water.7-9 Here we show that a racemic mixture of nanotubes exhibits CD when the SWNTs inherent to a chiral nanotube, or (ii) the inherent chirality of DNA induces the CD signal in a racemic

204

Ab Initio Studies of Vacancy-Defected Fullerenes and Single-Walled Carbon  

E-print Network

- vacancy-defected fullerenes, C60 and C70, and the single- and double-vacancy-defected single-walled carbon-vacancy-defected C60 on the triplet potential energy surface (PES) are lower than those on the singlet PES-vacancy-defected C60, such as C58, C56, and C54, can be made through laser irradiation [11]. Odd number

Wang, Yan Alexander

205

Scaling Properties in Transistors That Use Aligned Arrays of Single-Walled Carbon  

E-print Network

Scaling Properties in Transistors That Use Aligned Arrays of Single-Walled Carbon Nanotubes Xinning-performance transistors. This paper presents the results of systematic investigations of the dependence of device contacts of Pd yield transistors with effectively Ohmic contacts that exhibit negligible dependence

Rogers, John A.

206

CVD Growth of Single-Walled Carbon Nanotubes over Slit Apertures Watcharop Chaikittisilp1  

E-print Network

CVD CVD Growth of Single-Walled Carbon Nanotubes over Slit Apertures 1,2 Watcharop Chaikittisilp-grown SWNTs for the resolution of chiral selectivity of catalyst particles used in CVD process. SWNT CVD SWNT SWNT CVD SWNT CVD SWNT CVD SWNT CVD 1,2 Yoichi Murakami: Dept. of Chem. Sys. Eng

Maruyama, Shigeo

207

Aharonov-Bohm oscillation and chirality effect in optical activity of single-wall carbon nanotubes  

Microsoft Academic Search

We study the Aharonov-Bohm effect in the optical phenomena of single-wall carbon nanotubes (SWCN) and also their chirality dependence. Especially, we consider the natural optical activity as a proper observable and derive its general expression based on a comprehensive symmetry analysis, which reveals the interplay between the enclosed magnetic flux and the tubule chirality for arbitrary chiral SWCN. A quantitative

Fei Ye; Bing-Shen Wang; Zhao-Bin Su

2004-01-01

208

Aligned single-wall carbon nanotubes in composites by melt processing methods  

Microsoft Academic Search

This Letter describes the production of single-wall carbon nanotube (SWNT) – polymer composites with enhanced mechanical and electrical properties and exceptional nanotube alignment. A combination of solvent casting and melt mixing was used to disperse SWNT materials in poly(methyl methacrylate) (PMMA). Composite films showed higher conductivity along the flow direction than perpendicular to it. Composite fibers were melt spun to

R. Haggenmueller; H. H. Gommans; A. G. Rinzler; J. E. Fischer; K. I. Winey

2000-01-01

209

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

SciTech Connect

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.

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

2009-01-01

210

Production and applications of vertically aligned single-walled carbon nanotubes *Erik Einarsson  

E-print Network

-8656, Japan Synthesis of vertically aligned single-walled carbon nanotube (VA-SWNT) thin films by alcohol catalytic chemical vapor deposition has been clarified using an in situ optical absorbance measurement technique, which makes it possible to control the final film thickness. These VA-SWNT films can be detached

Maruyama, Shigeo

211

High Yield Fabrication of Single-Walled Carbon Nanotube Devices via Self-Assembly  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNTs) are attractive materials for many technological applications. Success in the large-scale integration of SWCNTs will depend upon progress in processing to address challenges such as separation, chemical doping and selective placement. This work will highlight recent progress in the selective placement of SWCNTs into predefined positions on gate oxide surfaces, allowing for the fabrication of large

George S. Tulevski; James B. Hannon; Ali Afzali

2007-01-01

212

Electrochemically Functionalized Single-Walled Carbon Nanotube Ting Zhang,a  

E-print Network

of nanotube-bound carboxylic acids with the amine-rich PABS [7]. Pd decorated SWNTs created by electron-beam Accepted: April 25, 2006 Abstract We demonstrate a facile fabrication method to make chemical gas sensors sensitivity, detection limit, and reproducibility. Keywords: Single-walled carbon nanotubes, Conducting

213

Growth Control of Vertically-Aligned Single-Walled Carbon Nanotubes from Alcohol  

E-print Network

Growth Control of Vertically-Aligned Single-Walled Carbon Nanotubes from Alcohol S. Maruyama, R. Murakami, S. Chiashi, Y. Miyauchi, M. Hu, M. Ogura, T. Okubo, S. Maruyama, Chem. Phys. Lett. 385 (2004) 298. [2] Y. Murakami, E. Einarsson, T. Edamura, S. Maruyama, Phys. Rev. Lett., 94 (2005) 087402. [3] S

Maruyama, Shigeo

214

Growth Control of Vertically Aligned Single-Walled Carbon Shigeo Maruyama  

E-print Network

Growth Control of Vertically Aligned Single-Walled Carbon Nanotubes Shigeo Maruyama Department. Chiashi, Y. Miyauchi, M. Hu, M. Ogura, T. Okubo, S. Maruyama, Chem. Phys. Lett. 385 (2004) 298. [2] Y. Murakami, E. Einarsson, T. Edamura, S. Maruyama, Phys. Rev. Lett., 94 (2005) 087402. [3] S. Maruyama, E

Maruyama, Shigeo

215

ACCVD Growth of Vertically Aligned Single-Walled Carbon Nanotubes on a Quartz Substrate  

E-print Network

Maruyama* , Yoichi Murakami, Erik Einarsson, and Tadao Edamura Department of Mechanical Engineering: maruyama@photon.t.u-tokyo.ac.jp Vertically aligned single-walled carbon nanotubes (SWNTs) up to 5 microns Raman studies of vertically aligned SWNTs. References [1] S. Maruyama, R. Kojima, Y. Miyauchi, S

Maruyama, Shigeo

216

Sensitive Detection of H2S Using Gold Nanoparticle Decorated Single-Walled Carbon  

E-print Network

Sensitive Detection of H2S Using Gold Nanoparticle Decorated Single-Walled Carbon Nanotubes Syed sensitive conducto- metric gas nanosensors for H2S can be synthesized by electrodepositing gold allowed for tuning of the size and number of gold nanoparticles deposited. The best H2S sensing

217

Simultaneous Rayleigh and Raman spectroscopy on suspended single-walled carbon nanotubes under electrostatic gating  

Microsoft Academic Search

The optical properties of single-walled carbon nanotubes (SWNTs) under electrostatic gating are of great interest for fundamental understanding of one-dimensional physics and for their application as optoelectronics devices. Here, we report how the electronic transitions are modified by gating conditions through direct measurements of Rayleigh (elastic) light scattering from individual suspended SWNTs [1]. With increasing gate voltage, we observed both

Yuhei Miyauchi; Zhengyi Zhang; Mitsuhide Takekoshi; Vikram Deshpande; Stéphane Berciaud; Philip Kim; James Hone; Tony Heinz

2011-01-01

218

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 ...

219

Impedimetric microbial biosensor based on single wall carbon nanotube modified microelectrodes for trichloroethylene detection  

Microsoft Academic Search

Contamination of soils and groundwaters with persistent organic pollutants is a matter of increasing concern. The most common organic pollutants are chlorinated hydrocarbons such as perchloroethylene and trichloroethylene (TCE). In this study, we developed a bacterial impedimetric biosensor for TCE detection, based on the immobilization of Pseudomonas putida F1 strain on gold microelectrodes functionalized with single wall carbon nanotubes covalently

M. Hnaien; S. Bourigua; F. Bessueille; J. Bausells; A. Errachid; F. Lagarde; N. Jaffrezic-Renault

220

Functionalized single-walled carbon nanotubes for composite applications and radiation studies  

Microsoft Academic Search

This dissertation offers a hopeful advance towards our future in space. Materials for space applications need to be strong, lightweight, and be multifunctional. Single-walled carbon nanotubes (SWNTs) have various properties that fit these criteria as a novel material for space and biomedical applications. To utilize SWNTs for this purpose, new chemical functionalization schemes need to be developed and studied. Fluorinated

Merlyn Xavier Pulikkathara

2009-01-01

221

Studies of Mechanically Deformed Single Wall Carbon Nanotubes and Graphene by Optical Spectroscopy  

E-print Network

FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE GRADUATE SCHOOL OF ARTS AND SCIENCES COLUMBIA UNIVERSITY 2009 #12. For the electromechanical property, the effect of uniaxial strain on the optical transition energies of single-walled carbon of the Raman spectra of optical phonons in graphene monolayers under tunable uniaxial tensile stress. All

Hone, James

222

Optical Characterization of Single-Walled Carbon Nanotubes Synthesized by Catalytic Decomposition of Alcohol  

E-print Network

of Alcohol Shigeo Maruyama, Yuhei Miyauchi, Yoichi Murakami and Shohei Chiashi Department of Mechanical The single-walled carbon nanotubes (SWNTs) synthesized by a catalytic decomposition of alcohol (Alcohol CVD feasible solution to this concern, we have proposed the use of alcohol, especially ethanol and methanol

Maruyama, Shigeo

223

Composites of Single-Walled Carbon Nanotubes and Styrene-Isoprene  

E-print Network

Composites of Single-Walled Carbon Nanotubes and Styrene-Isoprene Copolymer Latices Mai L. P. Ha are an excellent material to incorporate with polymers. There have been an Full Paper Composites of a styrene, as well as by mixing dispersed SWNTs with a styrene-isoprene copolymer latex after polymerization

Resasco, Daniel

224

Polarization State Control of Light by Single-Walled Carbon Nanotubes  

E-print Network

Society of America OCIS codes: (260.5430) Polarization; (240.0310) Thin films, (060.2340) Fiber optics components I. Introduction Single-walled carbon nano-tubes (SWCNTs) have been the subject of focused multi as saturable absorbers in mode locking of erbium doped silica fiber lasers have been reported[2,3]. Control

Maruyama, Shigeo

225

Electrochemical behaviour of single walled carbon nanotubes – Hydrogen storage and hydrogen evolution reaction  

Microsoft Academic Search

The electrochemical behaviour of single walled carbon nanotubes (SWCNT) related to the mechanism involved in the hydrogen electrode reaction applying electrochemical and spectroscopic techniques is studied. Cyclic voltammetry applied to electrodes containing different percentages of SWCNT demonstrates that this material can behave as efficient capacitor and that the hydrogen electrode reaction develops through the H-electrosorption followed by the formation of

P. S. Fernández; E. B. Castro; S. G. Real; M. E. Martins

2009-01-01

226

Controlled Growth of Single-Walled Carbon Nanotubes for CNT-Si heterojunction solar cell  

E-print Network

treatment to build up SWNTs to a self-assembled micro-honeycomb network for the application of solar cellsControlled Growth of Single-Walled Carbon Nanotubes for CNT-Si heterojunction solar cell Shigeo two different SWNT assemblies for SWNT-Si heterojuction solar cells. We proposed a water vapor

Maruyama, Shigeo

227

CNT-Si heterojunction solar cell with single-walled carbon nanotubes Shigeo Maruyama  

E-print Network

solar cells. We proposed a water vapor treatment to build up SWNTs to a self-assembled microCNT-Si heterojunction solar cell with single-walled carbon nanotubes Shigeo Maruyama Department-honeycomb network for the application of solar cells [1]. The micro- honeycomb network consists of vertical

Maruyama, Shigeo

228

CNT-SI HETEROJUNCTION SOLAR CELLS WITH STRUCTURE-CONTROLLED SINGLE-WALL CARBON NANOTUBE FILMS  

E-print Network

solar cells. We proposed a water-vapor treatment to build up SWNTs to a self-assembled micro- honeycombCNT-SI HETEROJUNCTION SOLAR CELLS WITH STRUCTURE- CONTROLLED SINGLE-WALL CARBON NANOTUBE FILMS network for the application of solar cells [1]. The micro-honeycomb network consists of vertical

Maruyama, Shigeo

229

Small angle neutron scattering from single-wall carbon nanotube suspensions: evidence for isolated  

E-print Network

Small angle neutron scattering from single-wall carbon nanotube suspensions: evidence for isolated online: Abstract We report small angle neutron scattering (SANS) from dilute suspensions of purified University, Houghton, MI 49931, USA e NIST Center for Neutron Research, National Institute of Standards

Wang, Howard "Hao"

230

Microwave shielding of transparent and conducting single-walled carbon nanotube films  

E-print Network

Microwave shielding of transparent and conducting single-walled carbon nanotube films Hua Xu films in the microwave frequency range from 10 MHz to 30 GHz by using the Corbino reflection technique from temperatures of 20­400 K. Based on the real and imaginary parts of the microwave conductivity

Gruner, George

231

Field Emission Properties of Single-Walled Carbon Nanotubes with a Variety of Emitter-Morphologies  

E-print Network

1 Field Emission Properties of Single-Walled Carbon Nanotubes with a Variety of Emitter sites was controlled by emitter morphologies combined with texturing of Si substrates. SWNTs grown and a random network of SWNTs prepared on flat Si substrates. Emitter morphology resulting in improved field

Maruyama, Shigeo

232

Field Emission Properties of Single-Walled Carbon Nanotubes with a Variety of Emitter-Morphologies  

E-print Network

Field Emission Properties of Single-Walled Carbon Nanotubes with a Variety of Emitter, that is, a large number density of emission sites resulting in a mild current per emitter. We focus here on SWNT-emitters prepared using alcohol catalytic CVD (ACCVD)1 . Prior to application of ACCVD for device

Maruyama, Shigeo

233

Single-walled Carbon Nanotubes Are a New Class of Ion Channel Blockers  

Microsoft Academic Search

Here we identify a novel class of biological membrane ion channel blockers called single-walled carbon nano- tubes (SWNTs). SWNTs with diameter distributions peaked at 0.9 and 1.3 nm, C60 fullerenes, multi wall nanotubes (MWNTs), and hyperfullerenes (nano-\\

Ki Ho Park; Manish Chhowalla; Zafar Iqbal; Federico Sesti

2003-01-01

234

Single-Walled Carbon Nanotube-Based Chemiresistive Affinity Biosensors for Small Molecules: Ultrasensitive Glucose Detection  

E-print Network

Single-Walled Carbon Nanotube-Based Chemiresistive Affinity Biosensors for Small Molecules such as nanowires, nanobelts and nanotubes as transducer elements in affinity (bio)sensors. Use of nanomaterials are affinity sensors wherein the binding of the analyte (generally a large, charged antigen) to the bioreceptor

Chen, Wilfred

235

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

PubMed

Orient and conduct: Triphenylene-based discotic ionic liquid crystals (ILCs) with six imidazolium ion pendants can disperse pristine single-walled carbon nanotubes (SWNTs). When the ILC is columnarly assembled, doping with SWNTs results in macroscopic homeotropic columnar orientation. Combination of shear and annealing treatments gives rise to three different orientation states, which determine the anisotropy of electrical conduction. PMID:22821897

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

2012-08-20

236

Diffusive-Ballistic Heat Conduction along a Single-Walled Carbon Nanotube Shigeo Maruyama  

E-print Network

Diffusive-Ballistic Heat Conduction along a Single-Walled Carbon Nanotube Shigeo Maruyama *E-mail address: maruyama@photon.t.u-tokyo.ac.jp The diffusive-ballistic heat conduction of finite at room temperature. A gradual transition from nearly pure ballistic to diffusive-ballistic heat

Maruyama, Shigeo

237

Ballistic switching and rectification in single wall carbon nanotube Y junctions  

E-print Network

Ballistic switching and rectification in single wall carbon nanotube Y junctions Antonis N that such junctions, when symmetric, can support both ballistic rectification and/or the ballistic switching operating if the SWCN Y junction can operate in the ballistic rectification BR and/or the ballistic switching BS mode

Srivastava, Deepak

238

Extinction and orientational dependence of electron diffraction from single-walled carbon nanotubes  

E-print Network

Extinction and orientational dependence of electron diffraction from single-walled carbon nanotubes; in final form 27 June 2005 Available online 1 August 2005 Abstract The extinction and orientational dependence and extinction of certain layer lines in experiment due to the interference of two primary Bessel

Qin, Lu-Chang

239

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 ...

240

In-situ spectroelectrochemical study of single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

Electrochemical doping of single-wall carbon nanotube (SWNT) films and concomtant changes in their electronic states were investigated by in situ optical absorption and Raman spectroscopy as well as by ac resistance measurements using non-aqueous electrolytic solution. Reversible variation of these properties induced by the shift in the electrode potential demonstrated the practicability of fine-tuning of their electronic states.

Kazaoui, S.; Minami, N.; Matsuda, N.; Kataura, H.; Achiba, Y.

2001-10-01

241

Range Analysis on the Wave Propagation Properties of a Single Wall Carbon Nano Tube  

Microsoft Academic Search

In this paper consistent bounds of the wave propagation properties concerning a Single Wall Carbon NanoTube (SWCNT) modeled as a Transmission Line are assessed. The monotonic inclusion property of the Interval Analysis leads to guaranteed limits for the given characteristics when the model parameters are uncertain. The common mode wave propagation in a SWCNT is considered and the variability range

B. de Vivo; L. Egiziano; P. Lamberti; V. Tucci

2008-01-01

242

Single walled carbon nano-tube, ferroelectric liquid crystal composites: Excellent diffractive tool  

Microsoft Academic Search

We present a switchable grating based on chiral single walled carbon nano-tube (SWCNT) doped ferroelectric liquid crystals (FLCs). The presence of SWCNTs improves the diffraction profile of the pure FLC. The diffraction efficiency, i.e., the ratio of intensities of first order and zero order maxima is more than 100% for the higher concentration of SWCNTs in pure FLC. This phenomenon

A. K. Srivastava; E. P. Pozhidaev; V. G. Chigrinov; R. Manohar

2011-01-01

243

Alcohol Vapor Sensors Based on Single-Walled Carbon Nanotube Field  

E-print Network

Alcohol Vapor Sensors Based on Single-Walled Carbon Nanotube Field Effect Transistors Takao Someya-effect transistor (FET) geometry and investigated the device response to alcoholic vapors. We observe significant changes in FET drain current when the device is exposed to various kinds of alcoholic vapors

Kim, Philip

244

MECHANISM BEHIND SEPARATION OF SINGLE-WALLED CARBON NANOTUBE VIA DENSITY  

E-print Network

Shiomi1 , Shohei Chiashi1 , and Shigeo Maruyama*,1 1 Department of Mechanical Engineering, 2 Global Center of Excellence for Mechanical Systems Innovation, The University of Tokyo, Tokyo 113-8656, Japan 3MECHANISM BEHIND SEPARATION OF SINGLE- WALLED CARBON NANOTUBE VIA DENSITY GRADIENT

Maruyama, Shigeo

245

Gas Sensing Mechanism of Gold Nanoparticles Decorated Single-Walled Carbon Nanotubes  

E-print Network

Gas Sensing Mechanism of Gold Nanoparticles Decorated Single- Walled Carbon Nanotubes Syed Mubeen towards different gas analytes, however the sensing mechanism was not clearly elucidated. The detailed sensing mechanism of hybrid gold-SWNT nanostructures toward hydrogen sulfide was investigated using field

246

Adsorption of Nitro Aromatics on Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Recent experiments with arrays of carbon nanotubes reveal a strong conductivity response after exposure to aromatic molecules containing nitro functional groups, such as nitrobenzene and trinitrotoluene. The detection of these compounds is of particular interest in the use of nanotube arrays as chemical sensors. To develop an understanding of the microscopic mechanisms involved, we perform detailed ab initio calculations of adsorption geometries, charge configurations, and vibration spectra for these compounds on pristine armchair and zigzag nanotubes. We use density functional theory with localized orbitals in a cluster approach and the M05-2X functional that is appropriate for the weak interactions of physisorption for these systems. We find a strong increase in adsorption energy with the addition of each nitro group to a molecule (around 100 meV) and a gradual increase with nanotube size, in agreement with preliminary experimental results. For most of these compounds, little charge transfer (< 0.1 e) occurs. Finally, these calculations are compared with results for the adsorption at oxidation defects.

Alldredge, Erik; Badescu, Stefan; Reinecke, Thomas; Bajwa, Navdeep; Perkins, F. Keith; Snow, Eric

2009-03-01

247

Thermal transpiration through single walled carbon nanotubes and graphene channels  

SciTech Connect

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 (?{sub fw}), diffusivity (D), and viscosity of the fluid (?) 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.

Thekkethala, Joe Francis; Sathian, Sarith P., E-mail: sarith@nitc.ac.in [Computational Nanotechnology Laboratory, School of Nano Science and Technology, National Institute of Technology Calicut, Kozhikode, Kerala - 673601 (India)

2013-11-07

248

Optical Spectroscopy of Single-Walled Carbon Nanotubes Under Extreme Conditions  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) are one of the leading candidate materials to realize novel nanoscale photonic devices. In order to assess their performance characteristics as optoelectronic materials, it is crucial to examine their optical properties in highly non-equilibrium situations such as high magnetic fields, low temperatures, and under high photoexcitation. Therefore, we present our latest result on the magnetic susceptibility anisotropy of metallic carbon nanotubes due to the Aharonov-Bohm effect. Here, we performed magnetic linear dichroism on a metallic-enriched HiPco SWNT sample utilizing a 35 T Hybrid Magnet to measure absorption with light polarization both perpendicular and parallel to the magnetic field. By relating these values with the nematic order parameter for alignment, we found that the metallic carbon nanotubes do not follow a strict diameter dependence across the 7 chiralities present in our sample. In addition to the studying the absorption properties exhibited at high magnetic field, we performed temperature-dependent (300 K to 11 K) photoluminescence (PL) on HiPco SWNTs embedded in an iota-carrageenan matrix utilizing intense fs pulses from a wavelength-tunable optical parametric amplifier. We found that for each temperature the PL intensity saturates as a function of pump fluence and the saturation intensity increases from 300 K to a moderate temperature around 100-150 K. Within the framework of diffusion-limited exciton-exciton annihilation (EEA), we successfully estimated the density of 1D excitons in SWNTs as a function of temperature and chirality. These results coupled with our results of magnetic brightening, or an increase in PL intensity as a function of magnetic flux through each SWNT due to the Aharonov-Bohm effect, yield great promise that in the presence of a high magnetic field the density of excitons can be further increased.

Searles, Thomas A., Jr.

249

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

NASA Technical Reports Server (NTRS)

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.

Nikolaev, Pavel

2009-01-01

250

Nanocatalyst structure as a template to define chirality of nascent single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Chirality is a crucial factor in a single-walled carbon nanotube (SWCNT) because it determines its optical and electronic properties. A chiral angle spanning from 0° to 30° results from twisting of the graphene sheet conforming the nanotube wall and is equivalently expressed by chiral indexes (n,m). However, lack of chirality control during SWCNT synthesis is an obstacle for a widespread use of these materials. Here we use first-principles density functional theory (DFT) and classical molecular dynamics (MD) simulations to propose and illustrate basic concepts supporting that the nanocatalyst structure may act as a template to control the chirality during nanotube synthesis. DFT optimizations of metal cluster (Co and Cu)/cap systems for caps of various chiralities are used to show that an inverse template effect from the nascent carbon nanostructure over the catalyst may exist in floating catalysts; such effect determines a negligible chirality control. Classical MD simulations are used to investigate the influence of a strongly interacting substrate on the structure of a metal nanocatalyst and illustrate how such interaction may help preserve catalyst crystallinity. Finally, DFT optimizations of carbon structures on stepped (211) and (321) cobalt surfaces are used to demonstrate the template effect imparted by the nanocatalyst surface on the growing carbon structure at early stages of nucleation. It is found that depending on the step structure and type of building block (short chains, single atoms, or hexagonal rings), thermodynamics favor armchair or zigzag termination, which provides guidelines for a chirality controlled process based on tuning the catalyst structure and the type of precursor gas.

Gómez-Gualdrón, Diego A.; Zhao, Jin; Balbuena, Perla B.

2011-01-01

251

Ab initio study of magnetic and electronic properties of Fe-filled single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigate the electronic and magnetic properties of a metallic (3, 3) single-walled carbon nanotube (SWCNT) filled with a linear Fe nanowire, based on the ab initio spin-polarized density functional theory. We find that in the stable structure the Fe-filled (3, 3), (5, 0) SWCNTs exhibit semiconducting properties, and the Fe nanowires lose their magnetic moment, while the (4, 4), (5, 5), (6, 6), (6, 0) SWCNTs having larger radius with linear Fe nanowires are metallic, and show magnetic moments.

Rahman, M. M.; Kisaku, M.; Kishi, T.; Matsunaka, D.; Diño, W. A.; Nakanishi, H.; Kasai, H.

2004-12-01

252

Gold Nanorod/Single-Wall Carbon Nanotube Heterojunctions Formed Directly on Surfaces  

NASA Astrophysics Data System (ADS)

In this presentation we describe work on the formation of heterojunctions between single-wall carbon nanotubes (SWNTs) and one-dimensional (1D) gold nanorods (AuNRs) assembled directly on surfaces. The chemical procedure is a simple benchtop method using commercially available reagents. Au NRs are grown directly and selectively on surface-attached SWCNTs by depositing hexanethiolate-terminated Au monolayer protected clusters (MPCs) on the SWCNTs and growing Au MPCs into NRs by seed-mediated growth, involving reduction of AuCL4^- onto Au MPCs in the presence of cetyltrimethylammonium bromide (CTAB). UV-vis, AFM, and SEM show highly selective growth of Au on SWCNTs only. Different combinations of junctions are possible, including AuNRs connecting two CNTs or two AuNRs attached to one CNT. We also show that Au nanostructures enhance Raman scattering of SWNTs. Several NRs and CNTs integrated into a connected assembly were studied. Electrical measurements with contacts on the AuNRs of these heterostructures will be presented. Finally carbon-supported metal structures with unique size and shape may be useful in electrocatalysis or electrochemical sensing applications.

Jalilian, Romaneh; Mieszawska, Aneta; Zamborini, Francis; Sumanasekera, Gamini

2006-03-01

253

Magnetoconductance in single-wall carbon nanotubes: Electron-electron interaction and weak localization contributions  

NASA Astrophysics Data System (ADS)

The positive and negative magnetoconductance (MC) data [J. Vavro , Phys. Rev. B 71, 155410 (2005)] in various single-wall carbon nanotube samples are analyzed by taking into account the electron-electron interaction (EEI) contribution, in addition to the weak localization (WL) regime. The low field MC data shows an H2 dependence, in accordance with the EEI and WL models. The contribution from EEI to the total MC is further confirmed from the universal scaling of MC relation [ {??/T1/2} vs (H/T) plots], showing that EEI plays a significant role at higher fields and lower temperatures. Intrinsic parameters such as inelastic scattering length (lin) extracted for barely metallic sample ( 120S/cm at 300K ) follow the T-3/4 dependence due to the inelastic electron-electron scattering in the dirty limit. The lin for highly conducting sample ( 3570S/cm at 300K ) follows a T-0.4 dependence. The various order parameters helps us to characterize the system in a disorder-tuned metal-insulator transition scenario.

Choudhury, Paramita Kar; Jaiswal, Manu; Menon, Reghu

2007-12-01

254

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

PubMed

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

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

255

Nerve agent detection using networks of single-walled carbon nanotubes  

Microsoft Academic Search

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

J. P. Novak; E. S. Snow; E. J. Houser; J. L. Stepnowski; R. A. McGill

2003-01-01

256

Tensile strength of single-walled carbon nanotubes directly measured from their macroscopic ropes  

Microsoft Academic Search

20 mm long ropes consisting of soundly aligned single-walled carbon nanotube (SWNT) ropes, synthesized by the catalytic decomposition of hydrocarbons, were employed for direct tensile strength measurements. The average tensile strength of SWNT rope composites is as high as 3.6+\\/-0.4 GPa, similar to that of carbon fibers. The tensile strength of SWNT bundles was extrapolated from the strength of the

F. Li; H. M. Cheng; S. Bai; G. Su; M. S. Dresselhaus

2000-01-01

257

Synthesis and characterization of single-wall carbon nanotube-amorphous diamond thin-film composites  

Microsoft Academic Search

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

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

2002-01-01

258

Influence of single-walled carbon nanotubes on microbial availability of phenanthrene in sediment  

Microsoft Academic Search

Increasing production and use of single-walled carbon nanotubes (SWCNT) will inevitably lead to release of these nanoparticles\\u000a to aquatic ecosystems. Similar to black carbon (BC) particles, SWCNT have a high affinity for hydrophobic organic contaminants\\u000a (HOCs) and therefore the presence of SWCNT in sediment may lead to altered bioavailability of HOCs. We compared SWCNT with\\u000a biochar and charcoal on their

X. Y. Cui; F. Jia; Y. X. Chen; J. Gan

259

Functionalizing Single-Wall Carbon Nanotubes in Hollow Cathode Glow Discharges  

Microsoft Academic Search

A hollow cathode glow discharge was used to functionalize single-wall carbon nanotubes. This low temperature, solvent free,\\u000a facile and fast process may be used to efficiently attach various functional groups (COOH, OH, CH, NH2, NO2 and NO) to the open ends and sidewalls of carbon nanotubes. The presented technique yields a broader set of functional groups\\u000a being attached to the

M. Bystrzejewski; M. H. Rümmeli; T. Gemming; T. Pichler; A. Huczko; H. Lange

2009-01-01

260

Shape Engineerable Single Walled Carbon Nanotube Solid as a Flexible Conducting Mesoporous Material  

Microsoft Academic Search

We present a new form of carbon nanotubes (CNT) material where CNTs are aligned and packed densely in a bulk solid. This single-walled carbon nanotube (SWNT) solid is fabricated from liquid-induced collapse of the sparse as-grown SWNT forest synthesized by super-growth CVD [1], which results in a 20x increase in mass density and a 70x increase in the Vickers hardness

Don N. Futaba; Kenji Hata; Tatsuki Hiraoka; Takeo Yamada; Kohei Mizuno; Yuhei Hayamizu; Tatsunori Namai; Yozo Kakudate; Osamu Tanaike; Hiroaki Hatori; Koji Miyake; Shinya Sasaki; Motoo Yumura; Sumio Iijima

2006-01-01

261

Single-walled carbon nanotube synthesis using ferrocene and iron pentacarbonyl in a laminar flow reactor  

Microsoft Academic Search

A gas-phase process of single-walled carbon nanotube (SWCNT) formation, based on thermal decomposition of iron pentacarbonyl or ferrocene in the presence of carbon monoxide (CO), was investigated in ambient pressure laminar flow reactors in the temperature range of 600–1300°C. Ferrocene was found to be a better catalyst precursor in the studied conditions since iron pentacarbonyl decomposes at lower temperatures resulting

Anna Moisala; Albert G. Nasibulin; David P. Brown; Hua Jiang; Leonid Khriachtchev; Esko I. Kauppinen

2006-01-01

262

Chaotic Behavior and its Control in the Single-Wall Carbon Nanotube  

NASA Astrophysics Data System (ADS)

Using the direct perturbation technique, we obtained a general perturbed solution of single-wall carbon nanotube (SWNT). We also provided two necessary and sufficient conditions for boundedness of the perturbed solution. Theoretical analysis results and the corresponding numerical results showed that the perturbed solution of the SWNT was unbounded in generally, which indicated the chaotic behavior of the system. Moreover, we were able to control the chaos of the carbon nanotube by adjusting the system parameters.

Fang, Jianshu

2014-11-01

263

Covalent functionalization of single walled carbon nanotubes with peptide nucleic acid: Nanocomponents for molecular level electronics  

Microsoft Academic Search

Imparting molecular recognition to carbon nanotubes (CNTs) by conjugating them with bio-molecules has been an area of great interest as the resulting highly functionalized CNT-bioconjugates find their applications in various fields like molecular level electronics, pharmaceuticals, drug delivery, novel materials and many others. In this work we demonstrate the synthesis of functionally engineered single walled carbon nanotubes (SWNTs)-peptide nucleic acid

Krishna V. Singh; Rajeev R. Pandey; Xu Wang; Roger Lake; Cengiz S. Ozkan; Kang Wang; Mihrimah Ozkan

2006-01-01

264

Polypropylene \\/Single Wall Carbon Nano Tube Composites Crystallization Behavior and Fiber Processing Studies  

Microsoft Academic Search

Single Wall Carbon Nanotubes (SWNTs) produced using high-pressure carbon monoxide (HiPCO) process have been purified using the previously developed method to remove the catalytic impurities. Polypropylene (PP) with 1 wtmelt blended in a Haake mixer at 240oC. The resulting PP\\/SWNT blend was optically inhomogeneous. The polymer melt was filtered through a 300, 250, 120 and 80 mesh stainless steel filter

T. V. Sreekumar; Arup R. Bhattacharyya; Atul Kumar; Huina Guo; Satish Kumar; Lars Ericson; Richard E. Smalley

2002-01-01

265

Structure and Properties of poly (para phynelyne benzobisoxazole) (PBO) \\/single wall carbon nano tube composite fibers  

Microsoft Academic Search

The liquid crystalline compositions are prepared by the in-situ polycondensation of diamines and diacid monomers in the presence of single wall carbon nano tubes (SWNT). Processing of the new compositions into fibers provide hybrid materials with improved mechanical properties. The in-situ polymerizations were carried out in polyphosphoric acid (PPA). Carbon nano tubes as high as 10 wt.polymer weight have been

Satish Kumar; Xiefei Zhang; Arup R. Bhattacharyya; Byung G. Min; T. D. Dang; F. E. Arnold; Richard A. Vaia; S. Ramesh; P. A. Willis; R. H. Hauge; R. E. Smalley

2002-01-01

266

Single-walled carbon nanotubes in superacid: X-ray and calorimetric evidence for partly ordered H2SO4  

E-print Network

Single-walled carbon nanotubes in superacid: X-ray and calorimetric evidence for partly ordered H2. Smalley Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, USA Received 7 in the presence of single-walled carbon nanotubes SWNTs . X-ray scattering from aligned fibers immersed in acid

Natelson, Douglas

267

Resonant micro-Raman spectroscopy of aligned single-walled carbon nanotubes on a-plane sapphire  

E-print Network

of H2 at 900 �C. Simultaneous control of nano- tube orientation and position was achieved by patterningResonant micro-Raman spectroscopy of aligned single-walled carbon nanotubes on a-plane sapphire to characterize aligned single-walled carbon nanotubes grown on a-plane sapphire to address the alignment

Zhou, Chongwu

268

Electronic transitions in single-walled carbon nanotubes: A resonance Raman study P. M. Rafailov,* H. Jantoljak, and C. Thomsen  

E-print Network

nano- tubes. The sensitivity of the Raman cross section to the nano- tube band structure is enhancedElectronic transitions in single-walled carbon nanotubes: A resonance Raman study P. M. Rafailov Resonance excitation profiles of the high-frequency peaks in the Raman spectra of single-walled carbon

Nabben, Reinhard

269

Critical oxide thickness for efficient single-walled carbon nanotube growth on silicon using thin SiO2 diffusion barriers.  

PubMed

The ability to integrate carbon nanotubes, especially single-walled carbon nanotubes, seamlessly onto silicon would expand their range of applications considerably. Though direct integration using chemical vapor deposition is the simplest method, the growth of single-walled carbon nanotubes on bare silicon and on ultrathin oxides is greatly inhibited due to the formation of a noncatalytic silicide. Using X-ray photoelectron spectroscopy, we show that silicide formation occurs on ultrathin oxides due to thermally activated metal diffusion through the oxide. Silicides affect the growth of single-walled nanotubes more than multi-walled nanotubes due to the increased kinetics at the higher single-walled nanotube growth temperature. We demonstrate that nickel and iron catalysts, when deposited on clean silicon or ultrathin silicon dioxide layers, begin to form silicides at relatively low temperatures, and that by 900 degrees C, all of the catalyst has been incorporated into the silicide, rendering it inactive for subsequent single-walled nanotube growth. We further show that a 4-nm silicon dioxide layer is the minimum diffusion barrier thickness that allows for efficient single-walled nanotube growth. PMID:17193143

Simmons, Jason M; Nichols, Beth M; Marcus, Matthew S; Castellini, Olivia M; Hamers, Robert J; Eriksson, Mark A

2006-07-01

270

Cumulative and Continuous Laser Vaporization Synthesis of Single Wall Carbon Nanotubes and Nanohorns  

SciTech Connect

The conditions for the scaled synthesis of single wall carbon nanotubes (SWNTs) and single wall carbon nanohorns (SWNHs) by laser vaporization at high temperatures are investigated and compared using in situ diagnostics. An industrial Nd:YAG laser (600 W, 1-500 Hz repetition rate) with tunable pulse widths (0.5-50 ms) is utilized to explore conditions for high yield production. High-speed videography (50,000 frames/s) of the laser plume and pyrometry of the target surface are correlated with ex situ high resolution TEM analysis of the products for pure carbon targets and carbon/catalyst targets to understand the effects of the processing conditions on the resulting nanostructures. Carbon is shown to self-assemble into single-wall nanohorn structures at rates of ~ 1 nm/ms which is comparable to the catalystassisted SWNT growth rates. Two regimes of laser ablation, cumulative ablation by multiple pulses, and continuous ablation by individual pulses, were explored. Cumulative ablation with spatially overlapping 0.5 ms pulses is favorable for the high yield and production rate of SWNTs at ~ 6 g/h while continuous ablation by individual long laser pulses (~ 20 ms) at high temperatures results in the highest yield of SWNHs without graphitic impurities at ~ 10 g/h. Adjustment of the laser pulse width is shown to control SWNH morphology.

Puretzky, Alexander A [ORNL; Styers-Barnett, David J [ORNL; Rouleau, Christopher M [ORNL; Hu, Hui [ORNL; Zhao, Bin [ORNL; Ivanov, Ilia N [ORNL; Geohegan, David B [ORNL

2008-01-01

271

High electrical conductance enhancement in Au-nanoparticle decorated sparse single-wall carbon nanotube networks  

NASA Astrophysics Data System (ADS)

We report high electrical conductance enhancement in sparse single-walled carbon nanotube networks by decoration with Au nanoparticles. The optimized hybrid network exhibited a sheet resistance of 650 ? sq-1, 1/1500 of the resistance of the host undecorated network, with a negligible optical transmission penalty (>90% transmittance at 550 nm wavelength). The electrical transport at room temperature in the host and decorated networks was dominated by two-dimensional variable range hopping. The high conductance enhancement was due to positive charge transfer from the decorating Au nanoparticles in intimate contact with the host network causing a Fermi energy shift into the high density of states at a van Hove singularity and enhanced electron delocalization relative to the host network which beneficially modifies the hopping parameters in such a way that the network behaves as an integral whole. The effect is most pronounced when the nanoparticle diameter is comparable to the electron mean free path in the bulk material at room temperature and there is minimum nanoparticle agglomeration. For higher than optimal values of nanoparticle coverage or nanoparticle diameter, the conductance enhancement is countered by metallic inclusions in the current pathways that are of higher resistance than the variable range hopping-controlled elements.

McAndrew, Calum F.; Baxendale, Mark

2013-08-01

272

Absolute Absorptivity of Single-walled Carbon Nanotubes Employing a Pyroelectric Detector  

NASA Astrophysics Data System (ADS)

Optical properties are important for determining fundamental characteristics of carbon single-walled nanotube (SWNT) samples including purity, chirality, and tube diameter. Previously, we have estimated the volume fraction of metallic versus semiconducting tubes for highly purified SWNT bucky-paper on a pyroelectric detector from spectral responsivity measurements and an effective medium approximation to determine the dielectric function (1). Pyroelectric detector-based measurements are based on the thermalization of photons within the SWNT coating and provide a robust technique for measuring absolute absorptivity at normal incidence. Alternatively, we perform transmissivity measurements of SWNTs by employing a gold-black coated pyroelectric detector. Spectral responsivity measurements are made by direct substitution against a NIST calibrated detector such that quantitative changes in the volume fraction and purity of SWNT samples are revealed. These results will be compared to specular transmissivity measurements made by UV-VIS spectrometry. Raman spectroscopy will also serve to verify nanotube properties. (1) K.E.H. Gilbert, J.H. Lehman, A.C. Dillon and J.L. Blackburn Appl. Phys. Lett. 88, 143122 (2006).

Hurst, Katherine; Dillon, Anne; Lehman, John

2007-03-01

273

Selective Synthesis of Subnanometer Diameter Semiconducting Single-Walled Carbon Nanotubes  

SciTech Connect

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.

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

2010-01-01

274

Photon induced effects in molecular assemblies of single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Single Walled Carbon Nanotubes (SWNT) are important for devices and sensors based on nanotechnology. Future optoelectronic devices can be made from the assemblies of diverse nanostructured materials and SWNTs, providing enhanced functionality. "Molecular assembly" as suggested by Feynman and envisioned by Drexler requires directed self assembly of rigid molecular components. Rigid ruthenium complexes have very strong absorbance in the visible spectrum and charge transfer properties; whereas SWNTs have exceptional electron accepting and charge transport properties. We have shown specific binding of these complexes with the end of SWNTs. Samples have been characterized using atomic force microscopy, and scanning electron microscopy. Absorption and Raman spectroscopy shows charge transfer and diameter selective binding of these metallodendrimers onto SWNTs. Photon enhanced aggregation properties of SWNT due to these ruthenium complexes are demonstrated. Ruthenium centered phenanthroline complexes exhibit a strong metal to ligand charge transfer. We believe that the nanotube quenches charge from the ligand after the complex has been optically excited. This results in optically altering the carrier density, and therefore the transport properties of the nanotubes. Field effect transistors (FET) have been fabricated using e-beam and conventional lithography. Photon induced affects on the charge transport are shown. Optical gating is shown in the functionalized SWNT FET.

Chaturvedi, Harsh

275

Review of Laser Ablation Process for Single Wall Carbon Nanotube Production  

NASA Technical Reports Server (NTRS)

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 seem to help the conversion of the carbon from target into vapor phase to improve formation of nanotubes. The use of CW far infrared lasers reduced the need for the oven, at the expense of controlled ablation. Some of these variations are tried with different combinations and concentrations of metal catalysts (Nickel with Cobalt, Iron, Palladium and Platinum) different buffer gases (e.g. Helium); with different oven temperatures (Room temperature to 1473K); under different flow conditions (1 to 1000 kPa) and even different porosities of the graphite targets. It is to be noted that the original Cobalt and Nickel combination worked best, possibly because of improved carbonization with stable crystalline phases. The mean diameter and yield seemed to increase with increasing oven temperatures. Thermal conductivity of the buffer gas and flow conditions dictate the quality as well as quantity of the SWCNTs. Faster flows, lower pressures and heavier gases seem to increase the yields. This review will attempt to cover all these variations and their relative merits. Possible growth mechanisms under these different conditions will also be discussed.

Arepalli, Sivaram

2003-01-01

276

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

PubMed

Single-walled carbon nanotubes (SWNTs) have been used extensively for sensor fabrication due to its high surface to volume ratio, nanosized structure and interesting electronic property. Lack of selectivity is a major limitation for SWNTs-based sensors. However, surface modification of SWNTs with a suitable molecular recognition system can enhance the sensitivity. On the other hand, porphyrins have been widely investigated as functional materials for chemical sensor fabrication due to their several unique and interesting physico-chemical properties. Structural differences between free-base and metal substituted porphyrins make them suitable for improving selectivity of sensors. However, their poor conductivity is an impediment in fabrication of prophyrin-based chemiresistor sensors. The present attempt is to resolve these issues by combining freebase- and metallo-porphyrins with SWNTs to fabricate SWNTs-porphyrin hybrid chemiresistor sensor arrays for monitoring volatile organic carbons (VOCs) in air. Differences in sensing performance were noticed for porphyrin with different functional group and with different central metal atom. The mechanistic study for acetone sensing was done using field-effect transistor (FET) measurements and revealed that the sensing mechanism of ruthenium octaethyl porphyrin hybrid device was governed by electrostatic gating effect, whereas iron tetraphenyl porphyrin hybrid device was governed by electrostatic gating and Schottky barrier modulation in combination. Further, the recorded electronic responses for all hybrid sensors were analyzed using a pattern-recognition analysis tool. The pattern-recognition analysis confirmed a definite pattern in response for different hybrid material and could efficiently differentiate analytes from one another. This discriminating capability of the hybrid nanosensor devices open up the possibilities for further development of highly dense nanosensor array with suitable porphyrin for E-nose application. PMID:22393460

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

2012-09-01

277

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

PubMed

We report interband magneto-optical spectra for single-walled carbon nanotubes in high magnetic fields up to 45 tesla, confirming theoretical predictions that the band structure of a single-walled carbon nanotube is dependent on the magnetic flux phi threading the tube. We have observed field-induced optical anisotropy as well as red shifts and splittings of absorption and photoluminescence peaks. The amounts of shifts and splittings depend on the value of phi/phi(0) and are quantitatively consistent with theories based on the Aharonov-Bohm effect. These results represent evidence of the influence of the Aharonov-Bohm phase on the band gap of a solid. PMID:15155942

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

2004-05-21

278

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

PubMed

We combine experiments and distinct element method simulations to understand the stability of rings and rackets formed by single-walled carbon nanotubes assembled into ropes. Bending remains a soft deformation mode in ropes because intra-rope sliding of the constituent nanotubes occurs with ease. Our simulations indicate that the formation of these aggregates can be attributed to the mesoscopic mechanics of entangled nanotubes and to the sliding at the contacts. Starting from the single-walled carbon nanotubes, the sizes of the rings and rackets' heads increase with the rope diameter, indicating that the stability of the experimental aggregates can be largely explained by the competition between bending and van der Waals adhesion energies. Our results and simulation method should be useful for understanding nanoscale fibers in general. PMID:25212697

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

2014-10-15

279

Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes into Dense, Aligned Rafts  

E-print Network

Single-walled carbon nanotubes are promising nanoelectronic materials but face long-standing challenges including production of pure semiconducting SWNTs and integration into ordered structures. Here, highly pure semiconducting single-walled carbon nanotubes are separated from bulk materials and self-assembled into densely aligned rafts driven by depletion attraction forces. Microscopy and spectroscopy revealed a high degree of alignment and a high packing density of ~100 tubes/micron within SWNT rafts. Field-effect transistors made from aligned SWNT rafts afforded short channel (~150 nm long) devices comprised of tens of purely semiconducting SWNTs derived from chemical separation within a < 1 micron channel width, achieving unprecedented high on-currents (up to ~120 microamperes per device) with high on/off ratios. The average on-current was ~ 3-4 microamperes per tube. The results demonstrated densely aligned high quality semiconducting SWNTs for integration into high performance nanoelectronics.

Wu, Justin; Antaris, Alexander; Choi, Charina L; Xie, Liming; Wu, Yingpeng; Diao, Shuo; Chen, Changxin; Chen, Yongsheng; Dai, Hongjie

2013-01-01

280

A novel fluorescent aptasensor based on single-walled carbon nanohorns  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanohorns have been used to construct an aptasensor for the first time. This novel aptasensor was successfully used for the detection of thrombin with high sensitivity and excellent selectivity. This thrombin aptasensor has a detection limit of as low as 100 pM.Single-walled carbon nanohorns have been used to construct an aptasensor for the first time. This novel aptasensor was successfully used for the detection of thrombin with high sensitivity and excellent selectivity. This thrombin aptasensor has a detection limit of as low as 100 pM. Electronic supplementary information (ESI) available: Experimental section and supplementary figures. See DOI: 10.1039/c1nr10774g

Zhu, Shuyun; Han, Shuang; Zhang, Ling; Parveen, Saima; Xu, Guobao

2011-11-01

281

Absolute potential of the Fermi level of single-walled carbon nanotubes via hydrogenase complex formation.  

NASA Astrophysics Data System (ADS)

The absolute potential of the Fermi level of nanotubes as a function of nanotube type is not presently understood, and is important for many nanotube applications and sorting strategies. Here, we study complexes of recombinant [FeFe] hydrogenases and single-walled carbon nanotubes. We find evidence that novel charge-transfer complexes are formed and are stable, which enables further study and application of this system. The hydrogenase functions as a hydrogen electrode sensitizing the nanotubes to the redox half-reaction for hydrogen. Thus the potential can be altered by changing the molecular hydrogen concentration, and this tunability is utilized to bleach various semiconducting nanotube transitions. By observing which are bleached and which remain emissive, we determine the alignment of the potential of the Fermi level of semiconducting single-walled carbon nanotubes. The experimentally determined Fermi level alignment is confirmed theoretically by the first-principles DFT-PBE method.

McDonald, Timothy; Svedruzic, Drazenka; Kim, Yong-Hyun; Blackburn, Jeffrey; Zhang, Shengbai; King, Paul; Heben, Michael

2007-03-01

282

Molecular dynamics simulation studies of structural and mechanical properties of single-walled carbon nanotubes.  

PubMed

Structural and mechanical properties of armchair, zig-zag and chiral single-walled carbon nanotubes are computed by employing Molecular Dynamics simulation technique using Discover code with Compass force field via Materials Studio program developed by the Accelrys. Consistent with the literature, we find that the armchair SWCNT is energetically favored over zig-zag and chiral nanotubes. Predicted structural parameters agree well with experimental observations. Observed radial distribution functions show that the single-walled carbon nanotubes remain crystalline after exposing them to 300 K. The predicted Young's and the Shear moduli were in reasonable agreement with other reports. Our predictions show that the Young's modulus of the tubes increases as the diameter of the tube decreases. PMID:21121299

Mashapa, Matete G; Ray, Suprakas Sinha

2010-12-01

283

Functionalization of single-walled carbon nanotubes with silver nanoparticles using Tecoma stans leaf extract  

NASA Astrophysics Data System (ADS)

Bioreduction mechanism of Tecoma stans leaf extract for the extracellular synthesis of silver nanoparticles was investigated using ultraviolet-visible spectroscopy (UV-vis). Nanostructure of the bio synthesized silver particles was confirmed by transmission electron microscopic (TEM) analysis. Crystalline cubic phase of the synthesized silver nanoparticles was confirmed by X-ray diffraction (XRD) technique. Observed rapid reduction behavior of Tecoma stans leaf extract was effectively explored for the functionalization of single-walled carbon nanotubes (SWCNT) with silver nanoparticles. Scanning electron microscopic (SEM) and TEM characterization confirmed the functionalization of single walled carbon nanotubes with the silver nanoparticles and the size of silver nanoparticles were found to be in the range of ?5-10 nm.

Vivekanandhan, S.; Venkateswarlu, M.; Carnahan, D.; Misra, M.; Mohanty, A. K.; Satyanarayana, N.

2012-04-01

284

Diameter selective electron transfer from encapsulated ferrocenes to single-walled carbon nanotubes.  

PubMed

The diameter selective photoluminescence quenching of single-walled carbon nanotubes (SWCNTs) is observed upon ferrocene encapsulation, which can be attributed to electron transfer from the encapsulated ferrocenes to the SWCNTs. Interestingly, the dependence of the electron transfer process on the nanotube diameter is governed by the molecular orientation of the ferrocenes in the SWCNT rather than the reduction potentials of the SWCNT. PMID:25310793

Iizumi, Yoko; Suzuki, Hironori; Tange, Masayoshi; Okazaki, Toshiya

2014-10-24

285

Random networks and aligned arrays of single-walled carbon nanotubes for electronic device applications  

Microsoft Academic Search

Singled-walled carbon nanotubes (SWNTs), in the form of ultrathin films of random networks, aligned arrays, or anything in\\u000a between, provide an unusual type of electronic material that can be integrated into circuits in a conventional, scalable fashion.\\u000a The electrical, mechanical, and optical properties of such films can, in certain cases, approach the remarkable characteristics\\u000a of the individual SWNTs, thereby making

Qing Cao; John A. Rogers

2008-01-01

286

Phonon anomalies in the resonance Raman spectra of graphite and single-wall carbon nanotubes  

Microsoft Academic Search

Phonon dispersion relations for a graphene sheet and single-wall carbon nanotubes (SWNTs) are calculated within the extended tight-binding model that has recently been shown to accurately predict the optical transition energies in small-diameter SWNTs. Anomalies in the dispersion relations are found at certain high- symmetry points of the reciprocal lattice and these anomalies are attributed to the strong electron-phonon coupling.

Georgii G. Samsonidze; Hyungbin Son; Shin Grace Chou; Gene Dresselhaus; Mildred S. Dresselhaus; Riichiro Saito; Jie Jiang; Eduardo B. Barros; Antonio G. Souza Filho

2006-01-01

287

Structural measurements for single-wall carbon nanotubes by Raman scattering technique  

Microsoft Academic Search

The single-wall carbon nanotubes grown by different techniques have been investigated by Roman scattering and high resolution transmission electron microscopy (HRTEM). The tube diameter values and the tube distribution over diameter have been estimated from the position and shape of the low-frequency band in the Raman spectrum containing the ‘breathing” modes. The diameter-dependent enhancement of the Raman signals from the

E. D. Obraztsova; J.-M. Bonard; V. L. Kuznetsov; V. I. Zaikovskii; S. M. Pimenov; A. S. Pozarov; S. V. Terekhov; V. I. Konov; A. N. Obraztsov; A. P. Volkov

1999-01-01

288

CdSe quantum dot-single wall carbon nanotube complexes for polymeric solar cells  

Microsoft Academic Search

The development of lightweight, flexible polymeric solar cells which utilize nanostructured materials has been investigated. Incorporation of quantum dots (QDs) and single wall carbon nanotubes (SWNTs) into a poly(3-octylthiophene)-(P3OT) composite, has been shown to facilitate exciton dissociation and carrier transport in a properly structured device. Optimization towards an ideal electron acceptor for polymeric solar cells that exhibits high electron affinity

B. J. Landi; S. L. Castro; H. J. Ruf; C. M. Evans; S. G. Bailey; R. P. Raffaelle

2005-01-01

289

Flexible transparent conducting single-wall carbon nanotube film with network bridging method  

Microsoft Academic Search

We fabricated random network films of highly pure single-wall carbon nanotubes (SWCNTs) on flexible polyethylene terephthalate substrate by dip- and spray-coatings and their combination method for application to flexible transparent conducting films (TCFs). The dip-coating treatment was a more efficient method for fabricating the SWCNT-TCFs of high electrical conductivity without drastic drop in the optical transmittance, compared to the spray-coating

Young Il Song; Cheol-Min Yang; Dong Young Kim; Hirofumi Kanoh; Katsumi Kaneko

2008-01-01

290

Atomic Step-Templated Formation of Single-Wall Carbon Nanotube Patterns  

Microsoft Academic Search

Single-wall carbon nanotubes catalytically produced on miscut C-plane sapphire wafers grow along the 0.2nm-high atomic steps of the vicinal alpha-Al2O3 (0001) surfaces, yielding highly aligned, dense arrays of discrete nanotubes on a dielectric material [1]. The nanotubes reproduce the atomic features of the surface, including steps, facets and kinks. Microscopy, X-ray diffraction and single-nanotube Raman spectroscopy [2] shed light into

Ernesto Joselevich; Ado Jorio; Hyungbin Son

2005-01-01

291

Vertically oriented single-wall carbon nanotube\\/enzyme on silicon as biosensor electrode  

Microsoft Academic Search

Thin films of vertically aligned individual single-wall carbon nanotubes (SWNTs) were deposited on silicon using a chemical\\u000a vapor deposition (CVD) process. Oriented SWNT growth was achieved by employing two methods of catalyst precursor self-assembly\\u000a followed by ethanol CVD. Using the silicon substrate as the working electrode in an electrochemical cell and the enzyme ?-NAD\\u000a (nicotinamide adenine dinucleotide) synthetase dissolved in

Yubing Wang; Zafar Iqbal

2005-01-01

292

Photon-drag effect in single-walled carbon nanotube films.  

PubMed

We observed an interaction of single-walled carbon nanotube films with obliquely incident nanosecond laser radiation in visible and infrared regions generating unipolar voltage pulses replicating the shape of the laser pulses. The photoelectric signal significantly depends on the laser polarization and has maximum value at the laser beam incidence angle of ±65° and at the film thickness of 350 nm. The results are explained in the framework of the photon-drag effect. PMID:22112234

Mikheev, Gennady M; Nasibulin, Albert G; Zonov, Ruslan G; Kaskela, Antti; Kauppinen, Esko I

2012-01-11

293

Wafer scale synthesis of dense aligned arrays of single-walled carbon nanotubes  

Microsoft Academic Search

Here we present an easy one-step approach to pattern uniform catalyst lines for the growth of dense, aligned parallel arrays\\u000a of single-walled carbon nanotubes (SWNTs) on quartz wafers by using photolithography or polydimethylsiloxane (PDMS) stamp\\u000a microcontact printing (µCP). By directly doping an FeCl3\\/methanol solution into Shipley 1827 photoresist or polyvinylpyrrolidone (PVP), various catalyst lines can be well-patterned\\u000a on a wafer

Weiwei Zhou; Christopher Rutherglen; Peter J. Burke

2008-01-01

294

Strain paint: noncontact strain measurement using single-walled carbon nanotube composite coatings.  

PubMed

Composite coatings have been developed that reveal strains in underlying structural elements through noncontact optical measurement. Dilute individualized single-walled carbon nanotubes are embedded in a polymeric host and applied to form a thin coating. Strain in the substrate is transmitted through the polymer to the nanotubes, causing systematic and predictable spectral shifts of the nanotube near-infrared fluorescence peaks. This new method allows quick and precise strain measurements at any position and along any direction of the substrate. PMID:22694748

Withey, Paul A; Vemuru, Venkata Srivishnu M; Bachilo, Sergei M; Nagarajaiah, Satish; Weisman, R Bruce

2012-07-11

295

Discrete Atom Imaging of One-Dimensional Crystals Formed Within Single-Walled Carbon Nanotubes  

Microsoft Academic Search

The complete crystallography of a one-dimensional crystal of potassium iodide encapsulated within a 1.6-nanometer-diameter single-walled carbon nanotube has been determined with high-resolution transmission electron microscopy. Individual atoms of potassium and iodine within the crystal were identified from a phase image that was reconstructed with a modified focal series restoration approach. The lattice spacings within the crystal are substantially different from

Rüdiger R. Meyer; Jeremy Sloan; Rafal E. Dunin-Borkowski; Angus I. Kirkland; Miles C. Novotny; Sam R. Bailey; John L. Hutchison; Malcolm L. H. Green

2000-01-01

296

Quantum dots decorated single walled carbon nanotubes for multimodal cellular imaging  

Microsoft Academic Search

We present the quantum dots (QDs) decorated single walled carbon nanotubes (SWNT) nanohybrids (QD-SWNT) for multimodal cellular imaging via optical imaging and magnetic resonance imaging (MRI). The QD-SWNT has been synthesized by covalently linking QDs onto chitosan-functionalized SWNT. Incubating human embryonic kidney (HEK) cell line 293T cells with QD-SWNT demonstrates that the QD-SWNT shows highly intracellular labeling efficiency and enhanced

Ning Du; Bingdi Chen; Hui Zhang; Deren Yang

2010-01-01

297

Functionalization of single-walled carbon nanotubes using isotropic plasma treatment: Resonant Raman spectroscopy study  

SciTech Connect

Functionalization of single-walled carbon nanotubes (SWNTs) by isotropic plasma treatment was studied using resonant Raman spectroscopy. It was shown that plasma-induced functionalization results in the uniaxial isotropic constriction of the nanotubes but preserves their overall structural integrity. It was demonstrated that NH{sub 3}{center_dot}H{sub 2}O and hexamethyldisiloxan plasmas yield various types of conductivity for semiconducting SWNTs.

Utegulov, Zhandos N.; Mast, David B.; He Peng; Shi Donglu; Gilland, Robert F. [Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States); Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio 45221 (United States); Department of Electrical and Computer Engineering and Computer Science, University of Cincinnati, Cincinnati, Ohio 45221 (United States)

2005-05-15

298

Synthesis of single-walled carbon nanotubes by induction thermal plasma  

Microsoft Academic Search

The production of high quality single-walled carbon nanotubes (SWCNTs) on a bulk scale has been an issue of considerable interest.\\u000a Recently, it has been demonstrated that high quality SWCNTs can be continuously synthesized on large scale by using induction\\u000a thermal plasma technology. In this process, the high energy density of the thermal plasma is employed to generate dense vapor-phase\\u000a precursors

Keun Su Kim; Ala Moradian; Javad Mostaghimi; Yasaman Alinejad; Ali Shahverdi; Benoit Simard; Gervais Soucy

2009-01-01

299

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

300

Effects of pressure transmitting media on Raman features of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We have performed high pressure Raman studies of single-walled carbon nanotubes (SWCNTs) by using different organic solvents as the pressure transmitting medium (PTM). A linear dependence of pressure coefficient of Raman G band is found with the molecular weight of organic solvent. In addition, according to the experimental data and a comparative analysis of pressure measurement without the PTM, we explain the occurrence of plateau and hardening behavior of Raman G and D ? bands upon increasing pressure.

Gao, Kun; Dai, R. C.; Zhao, Z.; Zhang, Z. M.; Ding, Z. J.

2008-07-01

301

Single-Walled Carbon Nanotube Thin-Film Sensor for Ultrasensitive Gas Detection  

Microsoft Academic Search

We demonstrated a gas sensor fabricated by growing a single-walled carbon nanotube (SWNT) thin film directly on a conventional sensor substrate. NO2 and Cl2 were detected down to the ppb level under room-temperature operation with a fast response. Using an electrical breakdown technique, gas response sensitivity was improved by an order of magnitude. The relationship between gas concentration and sensor

Winadda Wongwiriyapan; Shin-ichi Honda; Hirofumi Konishi; Tomoaki Mizuta; Takashi Ikuno; Tatsuya Ito; Toru Maekawa; Kengo Suzuki; Hiroshi Ishikawa; Kenjiro Oura; Mitsuhiro Katayama

2005-01-01

302

Influence of nanoparticle size to the electrical properties of naphthalenediimide on single-walled carbon nanotube wiring  

NASA Astrophysics Data System (ADS)

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.

Tanaka, Hirofumi; Hong, Liu; Fukumori, Minoru; Negishi, Ryota; Kobayashi, Yoshihiro; Tanaka, Daisuke; Ogawa, Takuji

2012-06-01

303

Frequency-and electric-field-dependent conductivity of single-walled carbon nanotube networks of varying density  

E-print Network

Frequency- and electric-field-dependent conductivity of single-walled carbon nanotube networks October 2007; published 20 February 2008 We present measurements of the frequency- and electric-field-dependent conductivity of single-walled car- bon nanotube SWCNT networks of various densities. The ac conductivity

Gruner, George

304

Single-walled carbon nanotubes growing radially from YC2 particles  

NASA Astrophysics Data System (ADS)

In the primary soot produced by arc discharge using an yttrium carbide loaded anode, bundles of single-walled carbon nanotubes (SWT) are observed, protruding radially from YC2 particles coated with graphitic multilayers. The graphitic cages separating YC2 particle and SWT bundles fall into the narrow range of 10-20 layers. The morphology of the clusters suggests a two-step growth model: The radial SWT growth pattern is first initiated by catalytic action between the YC2 droplet and the carbon in the gas phase. Second, and upon cooling, the graphitic cage starts by segregating excess carbon from the YC2 bulk, arresting further growth of SWT.

Zhou, Dan; Seraphin, Supapan; Wang, Su

1994-09-01

305

Plasma-synthesized single-walled carbon nanotubes and their applications  

NASA Astrophysics Data System (ADS)

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.

Hatakeyama, R.; Kaneko, T.; Kato, T.; Li, Y. F.

2011-05-01

306

Control of the Diameter and Chiral Angle Distributions during Production of Single-wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

Nikolaev, Pavel; Holmes, William; Sosa, Edward; Boul, Peter; Arepalli, Sivaram; Yowell, Leonard

2008-01-01

307

Critical silicon dioxide thickness for CVD growth of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Chemical vapor deposition (CVD) has shown remarkable control over the efficient and directed assembly of single-walled carbon nanotubes, making CVD a primary growth method for device applications. Due to the high temperatures involved in CVD, the chemical compatibility between the substrate, feedstock, and catalyst must be understood. Using x-ray photoelectron spectroscopy (XPS), we have studied the evolution of the chemical state of an iron nitrate catalyst during the initial temperature ramp of a standard CVD process. Heating the catalyst on clean silicon or on silicon with a native oxide leads to the formation of a silicide at 800 ^oC, inhibiting single-walled nanotube growth. By 900 ^oC, a typical growth temperature, all of the iron catalyst has been incorporated into the silicide. Thicker silicon oxide layers, on the order of 10 nm, effectively prevent silicide formation, enabling high yield growth.

Simmons, J. M.; Hamers, R. J.; Eriksson, M. A.

2005-03-01

308

Reduced Carbon Solubility in Fe Nanoclusters and Implications for the Growth of Single-Walled Carbon Nanotubes  

E-print Network

Reduced Carbon Solubility in Fe Nanoclusters and Implications for the Growth of Single of the minimum temperature necessary for the growth. We address this phenomenon in terms of solubility of C in Fe of single-walled carbon nanotubes, corresponding to unaffected, reduced, and no solubility of C

Curtarolo, Stefano

309

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

310

The infinite possible growth ambients that support single-wall carbon nanotube forest growth.  

PubMed

We report the virtually infinite possible carbon feedstocks which support the highly efficient growth of single-wall carbon nanotubes (SWCNTs) using on the water-assisted chemical vapor deposition method. Our results demonstrate that diverse varieties of carbon feedstocks, in the form of hydrocarbons, spanning saturated rings (e.g. trans-deca-hydronaphthalene), saturated chains (e.g. propane), unsaturated rings (e.g. dicyclopentadiene), and unsaturated chains (e.g. ethylene) could be used as a carbon feedstocks with SWCNT forests with heights exceeding 100 ums. Further, we found that all the resultant SWCNTs possessed similar average diameter indicating that the diameter was mainly determined by the catalyst rather than the carbon feedstock within this synthetic system. A demonstration of the generality was the synthesis of a carbon nanotube forest from a highly unorthodox combination of gases where trans-decahydronaphthalene acted as the carbon feedstock and benzaldehyde acted as the growth enhancer. PMID:24276860

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

2013-01-01

311

Semiempirical study of hydrogen addition to single-walled carbon nanotubes  

SciTech Connect

Single-walled carbon nanotube models have been constructed by insertion of 10-carbon bracelets into C{sub 70} to form C{sub 90} and C{sub 120}. Semiempirical heats of vicinal hydrogenation along the sides of the tubes are {approximately}40 kcal/mol more endothermic (less stable) than addition to the endcaps. Based on the similarity of the endcaps to C{sub 60}, hydrogenation of nanotubes is estimated to be approximately thermoneutral; therefore, only relatively high energy dienes or other species are likely to yield stable addended products.

Cahill, P.A.

1995-07-01

312

Translocation of Single-Stranded DNA through Single-Walled Carbon Nanotubes1  

PubMed Central

We report the fabrication of devices in which one single-walled carbon nanotube (SWCNT) spans a barrier between two fluid reservoirs, enabling direct electrical measurement of ion transport through the tube. A fraction of the tubes pass anomalously high ionic currents. Electrophoretic transport of small single stranded DNA oligomers through these tubes is marked by large transient increases in ion current and was confirmed by PCR analysis. Each current pulse contains about 107 charges, an enormous amplification of the translocated charge. Carbon nanotubes simplify the construction of nanopores, permit new types of electrical measurements, and may open avenues for control of DNA translocation. PMID:20044570

Liu, Haitao; He, Jin; Tang, Jinyao; Liu, Hao; Pang, Pei; Cao, Di; Krstic, Predrag; Joseph, Sony; Lindsay, Stuart; Nuckolls, Colin

2009-01-01

313

Electronic properties of single-walled carbon nanotubes encapsulating a cerium organometallic compound  

Microsoft Academic Search

Single-walled carbon nanotubes are filled with a cerium organometallic\\u000a compound. Using core-level excitation spectroscopy we study the\\u000a electronic structure of specific atoms in this complex compound. From\\u000a X-ray absorption spectroscopy we show that the electronic configuration\\u000a of cerium is nearly trivalent. Resonant photoemission spectroscopy\\u000a provides further details of the valence electronic properties of cerium\\u000a as well as of carbon. Thermal

Hidetsugu Shiozawa; Christian Kramberger; Mark Ruemmeli; David Batchelor; Hiromichi Kataura; Thomas Pichler; S. Ravi P. Silva

2009-01-01

314

A comparative study of argon ion irradiated pristine and fluorinated single-wall carbon nanotubes  

SciTech Connect

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.

Fedoseeva, Yu. V.; Bulusheva, L. G.; Okotrub, A. V. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation); Vyalikh, D. V. [Institute of Solid State Physics, Dresden University of Technology, D-01062 Dresden (Germany); Fonseca, A. [NANOPART N.V., Kapeldreef 60, B-3001 Leuven (Belgium)

2010-12-14

315

Translocation of Single-Stranded DNA Through Single-Walled Carbon Nanotubes  

SciTech Connect

We report the fabrication of devices in which one single-walled carbon nanotube spans a barrier between two fluid reservoirs, enabling direct electrical measurement of ion transport through the tube. A fraction of the tubes pass anomalously high ionic currents. Electrophoretic transport of small single-stranded DNA oligomers through these tubes is marked by large transient increases in ion current and was confirmed by polymerase chain reaction analysis. Each current pulse contains about 10{sup 7} charges, an enormous amplification of the translocated charge. Carbon nanotubes simplify the construction of nanopores, permit new types of electrical measurements, and may open avenues for control of DNA translocation.

Liu, Haitao [Columbia University; He, Jin [Arizona State University; Tang, Jinyao [Columbia University; Liu, Hao [Arizona State University; Pang, Pei [Arizona State University; Cao, Di [Arizona State University; Krstic, Predrag S [ORNL; Joseph, Sony nmn [ORNL; Lindsay, Stuart [Arizona State University; Nuckolls, Colin [Columbia University

2009-01-01

316

Chiral angle dependence of resonance window widths in (2n+m) families of single-walled carbon nanotubes  

E-print Network

Raman spectra of isolated single-walled carbon nanotubes (SWNTs) were obtained for a wide range of laser excitation energies to study the resonance excitation window of the radial breathing mode feature for members of ...

Hsieh, Ya-Ping

317

Electronic detection of molecules on the exterior and molecular transport through the interior of single walled carbon nanotubes  

E-print Network

Single walled carbon nanotubes (SWNT) are unique materials with high surface to volume ratio and all atoms residing on the surface. Due to their tubular shape both exterior and interior of the SWNT are available for ...

Lee, Chang Young

2010-01-01

318

Alcohol CVD Growth of Horizontally Aligned Single-Walled Carbon Nanotubes on R-cut Crystal Quartz Substrates  

E-print Network

Alcohol CVD Growth of Horizontally Aligned Single-Walled Carbon Nanotubes on R-cut Crystal Quartz are desired. In this study, we performed alcohol chemical vapor deposition (CVD) growth [2] of SWCNTs on R

Maruyama, Shigeo

319

Organic/Hybrid nanoparticles and single-walled carbon nanotubes: preparation methods and chiral applications.  

PubMed

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 ?-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. Chirality 26:683-691, 2014. © 2014 Wiley Periodicals, Inc. PMID:24811353

Alhassen, Haysem; Antony, Vijy; Ghanem, Ashraf; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Ostrikov, Kostya Ken

2014-11-01

320

Simulation and vibrational analysis of thermal oscillations of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The first four flexural thermal vibrational modes of single-walled carbon nanotubes (SWCNTs) of various lengths and radii were studied using atomistic molecular dynamics within the framework of the Brenner interatomic potential and Fourier analysis. These simulations provide clear evidence for the failure of simplistic analytic models to accurately extract resonance frequencies as the ratio R/L between the tube radius and the length increases. They are in excellent agreement with the Timoshenko beam model, which includes the effect of both rotary inertia and of shearing deformation. In addition, our results partially resolve Yakobson’s paradox and provide an upper cutoff estimate for the effective SWCNT thickness.

Pine, Polina; Yaish, Yuval E.; Adler, Joan

2011-04-01

321

Inkjet printing of aligned single-walled carbon-nanotube thin films  

NASA Astrophysics Data System (ADS)

We report a method for the inkjet printing of aligned single-walled carbon-nanotube (SWCNT) films by combining inkjet technology with the strong wettability contrast between hydrophobic and hydrophilic areas based on the patterning of self-assembled monolayers. Both the drying process control using the strong wettability boundary and the coffee-stain effect strongly promote the aggregation of SWCNTs along the contact line of a SWCNT ink droplet, thereby demonstrating our achievement of inkjet-printed aligned SWCNT films. This method could open routes for developing high-performance and environmentally friendly SWCNT printed electronics.

Takagi, Yuki; Nobusa, Yuki; Gocho, Shota; Kudou, Hikaru; Yanagi, Kazuhiro; Kataura, Hiromichi; Takenobu, Taishi

2013-04-01

322

Intercalant-induced superbundle formation of single-wall carbon nanotubes.  

PubMed

The formation of a massive quantity of single-wall carbon nanotube (SWCNT) superbundles has been introduced through sonicating SWCNTs in tetramethylene sulfone/chloroform solution in which nitronium hexafluoroantimonate (NHFA) is dissolved. Most SWCNT bundles with the NHFA treatment are enlarged by about 10 times compared with those of the pristine sample. It is proposed that the formation of SWCNTs can occur in solution by formation of an SWCNT-intercalant charge complex. The specific surface area of the superbundle is almost doubled, while its micropore surface area is amplified by about 7 times. This development of microporosity results from the enhanced interstitial sites in the SWCNT superbundles. PMID:16852209

An, Kay Hyeok; Yang, Cheol-Min; Park, Jin Sung; Jeong, Seung Yol; Lee, Young Hee

2005-05-26

323

Light-induced instability of PbO-filled single-wall carbon nanotubes  

SciTech Connect

We investigated single-wall carbon nanotubes filled with lead oxide, PbO, by transmission electron microscopy and Raman spectroscopy. It is concluded that PbO crystallizes in the orthorombic phase forming nanowires inside the nanotubes. The positions of the PbO Raman lines are downshifted as compared to the bulk material as a result of the reduced dimensionality. As a consequence of the filling, nanotubes become sensitive to the laser irradiation. At higher laser power densities, they oxidize and the free PbO nanowires are left in the sample.

Hulman, Martin; Kuzmany, Hans; Costa, Pedro M.F.J.; Friedrichs, Steffi; Green, Malcolm L.H. [Institut fuer Materialphysik der Universitaet Wien, Vienna (Austria); Inorganic Chemistry Laboratory, University of Oxford (United Kingdom)

2004-09-13

324

Simultaneous Rayleigh and Raman spectroscopy on suspended single-walled carbon nanotubes under electrostatic gating  

NASA Astrophysics Data System (ADS)

The optical properties of single-walled carbon nanotubes (SWNTs) under electrostatic gating are of great interest for fundamental understanding of one-dimensional physics and for their application as optoelectronics devices. Here, we report how the electronic transitions are modified by gating conditions through direct measurements of Rayleigh (elastic) light scattering from individual suspended SWNTs [1]. With increasing gate voltage, we observed both a broadening and shift of the excitonic resonances in the Rayleigh scattering spectra. The influence of carrier doping on the optical resonances and, as gauged through simultaneous Raman measurements, on vibrational transitions will be discussed.[4pt] [1] M. Y. Sfeir et al., Science 306, 1540 (2004).

Miyauchi, Yuhei; Zhang, Zhengyi; Takekoshi, Mitsuhide; Deshpande, Vikram; Berciaud, Stéphane; Kim, Philip; Hone, James; Heinz, Tony

2011-03-01

325

Effects of ion beam heating on Raman spectra of single-walled carbon nanotubes  

SciTech Connect

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.

Hulman, Martin [Austrian Research Centers, A-2444 Seibersdorf (Austria); Danubia NanoTech s.r.o., Ilkovicova 3, 81219 Bratislava (Slovakia); Skakalova, Viera [Danubia NanoTech s.r.o., Ilkovicova 3, 81219 Bratislava (Slovakia); Max-Planck Institut fuer Festkoerperforschung, Heisenbergstr.1, 70569 Stuttgart (Germany); Krasheninnikov, A. V. [Materials Physics Division, University of Helsinki, P.O. Box 43, FI-00014 (Finland); Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, FI-02015 (Finland); Roth, S. [Max-Planck Institut fuer Festkoerperforschung, Heisenbergstr.1, 70569 Stuttgart (Germany)

2009-02-16

326

One-dimensional silver nanostructures on single-wall carbon nanotubes  

PubMed Central

We report the synthesis and characterization of one-dimensional silver nanostructures using single-wall carbon nanotubes (SWCNT) as a template material. Transmission electron microscopy and scanning tunneling microscopy are consistent with the formation of a one-dimensional array of silver particles on SWCNT. We observe evidence for the excitation of the longitudinal silver plasmon mode in the optical absorption spectra of Ag-SWCNT dispersions, even in the lowest silver concentrations employed. The results indicate that silver deposits on SWCNT may be candidates for light-to-energy conversion through the coupling of the electric field excited in arrays of plasmonic particles. PMID:22112230

2011-01-01

327

Temperature Dependence of the Thermal Conductivity of Single Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

Osman, Mohamed A.; Srivastava, Deepak

2000-01-01

328

On a Nanoscopically-Informed Shell Theory of Single-Wall Carbon Nanotubes  

E-print Network

This paper proposes a bottom-up sequence of modeling steps leading to a nanoscopically informed continuum, and as such macroscopic, theory of single-walled carbon nanotubes (SWCNTs). We provide a description of the geometry of the two most representative types of SWCNTs, armchair (A-) and zigzag (Z-), of their modules and of their elementary bond units. We believe ours to be the simplest shell theory that accounts accurately for the linearly elastic response of both A- and Z- CNTs. In fact, our theory can be shown to fit SWCNTs of whatever chirality; its main novel feature is perhaps the proposition of chirality-dependent concepts of effective thickness and effective radius.

Chandrajit Bajaj; Antonino Favata; Paolo Podio-Guidugli

2011-11-19

329

Oxygen plasma effects on the electrical conductance of single-walled carbon nanotube bundles  

NASA Astrophysics Data System (ADS)

We report the electrical properties of single-walled carbon nanotube bundles aligned between two electrodes with a gap of 8 µm by the alternating current dielectrophoresis method. The resistance increased exponentially as the number of structural defects increased from the oxygen plasma treatment. However, no noticeable change was observed in the carrier concentration and tube-tube interaction. The resistance dependence on the plasma treatment time was explained on the basis of the localization of electron states at defect sites. The aspects of the defects were examined by measuring the effects of ammonia adsorption on the conductance of the device.

Kim, Sanghun; Kim, Ho-Jong; Rag Lee, Hyeong; Song, Jung-Hoon; Yi, Sam Nyung; Ha, Dong Han

2010-08-01

330

Single-wall carbon nanotubes with adsorbed antibodies detect live breast cancer cells  

Microsoft Academic Search

Monoclonal antibodies (mAb) specific to cell surface antigens overexpressed on cancer cells adsorbed to single-wall carbon\\u000a nanotube (SWCNT) devices can bind to their antigens in a drop of buffer, resulting in a slight drop in conductance. Here we\\u000a report detection of live breast cancer cells with a mAb-SWCNT device. We adsorbed mAb specific to insulin-like growth factor\\u000a 1 receptor (IGF1R)

Balaji Panchapakesan; Gregory Cesarone; Shaoxin Liu; Kasif Teker; Eric Wickstrom

2005-01-01

331

In vivo photoacoustic molecular imaging with targeting single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Here we present that single-walled carbon nanotubes(SWNT) coated with poly(ethylene glycol) (PEG) can be used as a contrast agent for photoacoustic molecular imaging. In vitro and in vivo experiments results show a good enhancement of the optical absorption by SWNT in photoacoustic imaging. The experimental results also show that a high contrast and a high efficient targeting of integrin ?v?3 positive U87 human glioblastoma tumours in mice could be achieved. This study suggests that photoacoustic molecular imaging with antibody functionalized SWNTs has the potential to be an effective early tumor diagnoses method.

Xiang, Liangzhong; Xing, Da; Yuan, Yi; Huang, Lei

2008-12-01

332

Dispersion Interaction of Atoms with Single-Walled Carbon Nanotubes described by the Dirac Model  

E-print Network

We calculate the interaction energy and force between atoms and molecules and single-walled carbon nanotubes described by the Dirac model of graphene. For this purpose the Lifshitz-type formulas adapted for the case of cylindrical geometry with the help of the proximity force approximation are used. The results obtained are compared with those derived from the hydrodymanic model of graphene. Numerical computations are performed for hydrogen atoms and molecules. It is shown that the Dirac model leads to larger values of the van der Waals force than the hydrodynamic model. For a hydrogen molecule the interaction energy and force computed using both models are larger than for a hydrogen atom.

Yu. V. Churkin; G. L. Klimchitskaya; A. B. Fedortsov; V. A. Yurova

2011-08-30

333

Dispersion Interaction of Atoms with Single-Walled Carbon Nanotubes described by the Dirac Model  

E-print Network

We calculate the interaction energy and force between atoms and molecules and single-walled carbon nanotubes described by the Dirac model of graphene. For this purpose the Lifshitz-type formulas adapted for the case of cylindrical geometry with the help of the proximity force approximation are used. The results obtained are compared with those derived from the hydrodymanic model of graphene. Numerical computations are performed for hydrogen atoms and molecules. It is shown that the Dirac model leads to larger values of the van der Waals force than the hydrodynamic model. For a hydrogen molecule the interaction energy and force computed using both models are larger than for a hydrogen atom.

Churkin, Yu V; Fedortsov, A B; Yurova, V A

2011-01-01

334

Large Optical Nonlinearity of Semiconducting Single-Walled Carbon Nanotubes under Resonant Excitations  

NASA Astrophysics Data System (ADS)

We measured third-order nonlinear susceptibility (?(3)) spectra in semiconducting single-walled carbon nanotubes (SWNTs) by the Z-scan method. |Im?(3)| is remarkably enhanced under resonant excitation to the lowest interband transition, reaching 4.2×10-6 esu and 1.5×10-7 esu in SWNTs grown by the laser ablation and HiPco methods, respectively. A comparison of the transient absorption changes evaluated by degenerate and nondegenerate pump-probe measurements suggests that the resonant enhancement of |Im?(3)| is dominated by a coherent process rather than by saturation of absorption.

Maeda, A.; Matsumoto, S.; Kishida, H.; Takenobu, T.; Iwasa, Y.; Shiraishi, M.; Ata, M.; Okamoto, H.

2005-02-01

335

Light-controlled single-walled carbon nanotube dispersions in aqueous solution.  

PubMed

We have succeeded in dispersing single-walled carbon nanotubes (SWNTs) into an aqueous solution of poly(ethylene glycol)-terminated malachite green derivative (PEG-MG) through simple sonication. It was found that UV exposure caused reaggregation of these predispersed SWNTs in the same aqueous medium, as adsorbed PEG-MG photochromic chains could be effectively photocleavaged from the nanotube surface. The observed light-controlled dispersion and reaggragation of SWNTs in the aqueous solution should facilitate the development of SWNT dispersions with a controllable dispersity for potential applications. PMID:18672920

Chen, Senlin; Jiang, Yugui; Wang, Zhiqiang; Zhang, Xi; Dai, Liming; Smet, Mario

2008-09-01

336

Reinforcement of semicrystalline polymers with collagen-modified single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

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.

Bhattacharyya, Sanjib; Salvetat, Jean-Paul; Saboungi, Marie-Louise

2006-06-01

337

Ultrafast spectroscopy of midinfrared internal exciton transitions in separated single-walled carbon nanotubes.  

PubMed

We report a femtosecond midinfrared study of the broadband low-energy response of individually separated (6,5) and (7,5) single-walled carbon nanotubes. Strong photoinduced absorption is observed around 200 meV, whose transition energy, oscillator strength, resonant chirality enhancement, and dynamics manifest the observation of quasi-one-dimensional intraexcitonic transitions. A model of the nanotube 1s-2p cross section agrees well with the signal amplitudes. Our study further reveals saturation of the photoinduced absorption with increasing phase-space filling of the correlated e-h pairs. PMID:20482139

Wang, Jigang; Graham, Matt W; Ma, Yingzhong; Fleming, Graham R; Kaindl, Robert A

2010-04-30

338

Strain and friction induced by van der Waals interaction in individual single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Axial strain is introduced into individual single wall carbon nanotubes (SWCNTs) suspended from a trench-containing Si /SiO2 substrate by employing the van der Waals interaction between the SWCNT and the substrate. Resonance Raman spectroscopy is used to characterize the strain, and up to 3% axial strain is observed. It is also found that a significant friction between the SWCNT and the substrate, on the order of 10pN/nm, governs the localization and propagation of the strain in the SWCNTs sitting on the substrate. This method can be applied to introduce strain into materials sitting on a substrate, such as a graphene sheet.

Son, Hyungbin; Samsonidze, Georgii G.; Kong, Jing; Zhang, Yingying; Duan, Xiaojie; Zhang, Jin; Liu, Zhongfan; Dresselhaus, Mildred S.

2007-06-01

339

Molecular adsorption study of nicotine and caffeine on single-walled carbon nanotubes from first principles  

NASA Astrophysics Data System (ADS)

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.

Lee, Hyung-June; Kim, Gunn; Kwon, Young-Kyun

2013-08-01

340

Molecular dynamics simulation for flow characteristics in nanochannels and single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

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.

Yasuoka, H.; Imae, T.; Kaneda, M.; Suga, K.

2014-08-01

341

Stability and electronic structure of Si, Ge, and Ti substituted single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Si, Ge, and Ti substituted nanotubes have been theoretically investigated. We employed a mixed approach for the computation of the electronic structure of these systems under periodic conditions. Band energy methods were then employed at a pseudopotential and all-electron schemes. The optimized geometries, binding, and atom-substitution energies have been computed along with the details of the electronic structure and bonding characteristics. Our results indicate the feasibility of up to now hypothetical Ge and Ti large substitutions in single walled carbon nanotubes. We also discuss the electronic behavior and the nature of the bonding in this class of materials.

Galano, Annia; Orgaz, Emilio

2008-01-01

342

Single walled carbon nano-tube, ferroelectric liquid crystal composites: Excellent diffractive tool  

NASA Astrophysics Data System (ADS)

We present a switchable grating based on chiral single walled carbon nano-tube (SWCNT) doped ferroelectric liquid crystals (FLCs). The presence of SWCNTs improves the diffraction profile of the pure FLC. The diffraction efficiency, i.e., the ratio of intensities of first order and zero order maxima is more than 100% for the higher concentration of SWCNTs in pure FLC. This phenomenon has been explained by the decrease in ferroelectric domain periodicity, due to the doping of SWCNTs in pure FLC, and optical activity of the chiral SWCNTs. These gratings with very high diffraction efficiency may find application in many devices.

Srivastava, A. K.; Pozhidaev, E. P.; Chigrinov, V. G.; Manohar, R.

2011-11-01

343

Magnetic response of single-walled carbon nanotubes induced by an external magnetic field.  

PubMed

Using first-principles density functional calculations, magnetically induced currents are obtained for zigzag single-walled carbon nanotubes. Clear differences and trends in current flow are observed between the different nanotube families. In particular, for a magnetic field applied along the tube axis, the current response of the ? = 0 infinite nanotubes is paramagnetic, whereas for ? = 1 and 2 nanotubes, the response is diamagnetic. The results are used to predict and interpret the significant changes in NMR properties for small molecules encapsulated inside a tube. PMID:21171576

Kibalchenko, Mikhail; Payne, Mike C; Yates, Jonathan R

2011-01-25

344

Translocation of single-wall carbon nanotubes through solid-state nanopores.  

PubMed

We report the translocation of individual single-wall carbon nanotubes (SWNTs) through solid-state nanopores. Single-strand DNA oligomers are used to both disperse the SWNTs in aqueous solution and to provide them with a net charge, allowing them to be driven through the nanopores by an applied electric field. The resulting temporary interruptions in the measured nanopore conductance provide quantitative information on the diameter and length of the translocated nanotubes at a single-molecule level. Furthermore, we demonstrate that the technique can be utilized to monitor bundling of SWNT in solution by using complementary nucleotides to induce tube-tube agglomeration. PMID:21574581

Hall, Adam R; Keegstra, Johannes M; Duch, Matthew C; Hersam, Mark C; Dekker, Cees

2011-06-01

345

Green chemical functionalization of single-walled carbon nanotubes in ionic liquids.  

PubMed

Single walled carbon nanotubes (SWNTs) are exfoliated and functionalized predominantly as individuals by grinding them for minutes at room temperature with aryldiazonium salts in the presence of ionic liquids (ILs) and K(2)CO(3). This constitutes an extremely rapid and mild green chemical functionalization process for obtaining the individualized nanotube structures. A number of ILs and various reaction conditions were surveyed. Raman, XPS, UV/vis/NIR spectroscopies, thermogravimetric analysis, and atomic force and transmission electron microscopies were used to characterize the products. PMID:16231941

Price, B Katherine; Hudson, Jared L; Tour, James M

2005-10-26

346

Vibrational analysis of thermal oscillations of single-walled carbon nanotubes under axial strain  

NASA Astrophysics Data System (ADS)

The first four flexural vibrational modes of single-walled carbon nanotubes (SWCNTs) of various lengths under different axial strains were studied using atomistic molecular dynamics within the framework of the Brenner interatomic potential and Fourier analysis. The simulated results are in excellent agreement with the Timoshenko beam model, which includes the effect of both rotary inertia and of shearing deformation. From the crossing points of the simulation data with the expected resonance frequencies of the unstrained tubes an upper limit for the effective SWCNT thickness is found (?0.1 nm), with no adjustable parameters. This partially resolves Yakobson's paradox concerning scattered estimates for nanotube width.

Pine, Polina; Yaish, Yuval E.; Adler, Joan

2014-03-01

347

Single-Walled Carbon Nanotube Thin-Film Sensor for Ultrasensitive Gas Detection  

NASA Astrophysics Data System (ADS)

We demonstrated a gas sensor fabricated by growing a single-walled carbon nanotube (SWNT) thin film directly on a conventional sensor substrate. NO2 and Cl2 were detected down to the ppb level under room-temperature operation with a fast response. Using an electrical breakdown technique, gas response sensitivity was improved by an order of magnitude. The relationship between gas concentration and sensor response was derived based on the Langmuir adsorption isotherm, predicting a detection limit of 8 ppb for NO2. The SWNT thin-film gas sensor exhibits merits over other types of sensors by virtue of its simplicity in fabrication and feasible application.

Wongwiriyapan, Winadda; Honda, Shin-ichi; Konishi, Hirofumi; Mizuta, Tomoaki; Ikuno, Takashi; Ito, Tatsuya; Maekawa, Toru; Suzuki, Kengo; Ishikawa, Hiroshi; Oura, Kenjiro; Katayama, Mitsuhiro

2005-04-01

348

Reinforcement of single-walled carbon nanotube bundles by intertube bridging.  

PubMed

During their production, single-walled carbon nanotubes form bundles. Owing to the weak van der Waals interaction that holds them together in the bundle, the tubes can easily slide on each other, resulting in a shear modulus comparable to that of graphite. This low shear modulus is also a major obstacle in the fabrication of macroscopic fibres composed of carbon nanotubes. Here, we have introduced stable links between neighbouring carbon nanotubes within bundles, using moderate electron-beam irradiation inside a transmission electron microscope. Concurrent measurements of the mechanical properties using an atomic force microscope show a 30-fold increase of the bending modulus, due to the formation of stable crosslinks that effectively eliminate sliding between the nanotubes. Crosslinks were modelled using first-principles calculations, showing that interstitial carbon atoms formed during irradiation in addition to carboxyl groups, can independently lead to bridge formation between neighbouring nanotubes. PMID:14991016

Kis, A; Csányi, G; Salvetat, J-P; Lee, Thien-Nga; Couteau, E; Kulik, A J; Benoit, W; Brugger, J; Forró, L

2004-03-01

349

Single-walled carbon nanotubes as stationary phase in gas chromatographic separation and determination of argon, carbon dioxide and hydrogen  

Microsoft Academic Search

A chromatographic technique is introduced based on single-walled carbon nanotubes (SWCNTs) as stationary phase for separation of Ar, CO2 and H2 at parts per million (ppm) levels. The efficiency of SWCNTs was compared with solid materials such as molecular sieve, charcoal, multi-walled carbon nanotubes and carbon nanofibers. The morphology of SWCNTs was optimized for maximum adsorption of H2, CO2 and

Afsaneh Safavi; Norooz Maleki; Mohammad Mahdi Doroodmand

2010-01-01

350

Changing chirality during single-walled carbon nanotube growth: a reactive molecular dynamics/Monte Carlo study.  

PubMed

The growth mechanism and chirality formation of a single-walled carbon nanotube (SWNT) on a surface-bound nickel nanocluster are investigated by hybrid reactive molecular dynamics/force-biased Monte Carlo simulations. The validity of the interatomic potential used, the so-called ReaxFF potential, for simulating catalytic SWNT growth is demonstrated. The SWNT growth process was found to be in agreement with previous studies and observed to proceed through a number of distinct steps, viz., the dissolution of carbon in the metallic particle, the surface segregation of carbon with the formation of aggregated carbon clusters on the surface, the formation of graphitic islands that grow into SWNT caps, and finally continued growth of the SWNT. Moreover, it is clearly illustrated in the present study that during the growth process, the carbon network is continuously restructured by a metal-mediated process, thereby healing many topological defects. It is also found that a cap can nucleate and disappear again, which was not observed in previous simulations. Encapsulation of the nanoparticle is observed to be prevented by the carbon network migrating as a whole over the cluster surface. Finally, for the first time, the chirality of the growing SWNT cap is observed to change from (11,0) over (9,3) to (7,7). It is demonstrated that this change in chirality is due to the metal-mediated restructuring process. PMID:21923157

Neyts, Erik C; van Duin, Adri C T; Bogaerts, Annemie

2011-11-01

351

Systematical analysis of mode-locked fiber lasers using single-walled carbon nanotube saturable absorbers  

NASA Astrophysics Data System (ADS)

The output characteristics of the Er-doped mode-locked fiber laser using a single-walled carbon nanotube saturable absorber are investigated theoretically with a nonlinear Schrödinger equation and a saturable absorption equation using realistic parameters. Stable self-starting mode-locking pulses are achieved under net normal, net zero, and net anomalous cavity group velocity dispersion (GVD) respectively. A spectrum with a flat top is obtained from the net normal cavity GVD laser while a spectrum with Kelly side-bands is obtained from the net anomalous cavity GVD laser. The characteristics of the pulse duration changing with cavity GVD and modulation depth of the single-walled carbon nanotubes are discussed. The characteristics of the mode-locking pulses from net normal, net zero, and net anomalous cavity GVD mode-locked fiber lasers are compared. These systematical results are useful for designing mode-locked fiber lasers with saturable absorbers made by different kinds of carbon nano-materials.

Zhang, Xiao; Song, Yan-Rong

2014-06-01

352

Encapsulation of carbon chain molecules in single-walled carbon nanotubes.  

PubMed

The vacuum space inside carbon nanotubes offers interesting possibilities for the inclusion, transportation, and functionalization of foreign molecules. Using first-principles density functional calculations, we show that linear carbon-based chain molecules, namely, polyynes (C(m)H(2), m = 4, 6, 10) and the dehydrogenated forms C(10)H and C(10), as well as hexane (C(6)H(14)), can be spontaneously encapsulated in open-ended single-walled carbon nanotubes (SWNTs) with edges that have dangling bonds or that are terminated with hydrogen atoms, as if they were drawn into a vacuum cleaner. The energy gains when C(10)H(2), C(10)H, C(10), C(6)H(2), C(4)H(2), and C(6)H(14) are encapsulated inside a (10,0) zigzag-shaped SWNT are 1.48, 2.04, 2.18, 1.05, 0.55, and 1.48 eV, respectively. When these molecules come inside a much wider (10,10) armchair SWNT along the tube axis, they experience neither an energy gain nor an energy barrier. They experience an energy gain when they approach the tube walls inside. Three hexane molecules can be encapsulated parallel to each other (i.e., nested) inside a (10,10) SWNT, and their energy gain is 1.98 eV. Three hexane molecules can exhibit a rotary motion. One reason for the stability of carbon chain molecules inside SWNTs is the large area of weak wave function overlap. Another reason concerns molecular dependence, that is, the quadrupole-quadrupole interaction in the case of the polyynes and electron charge transfer from the SWNT in the case of the dehydrogenated forms. The very flat potential surface inside an SWNT suggests that friction is quite low, and the space inside SWNTs serves as an ideal environment for the molecular transport of carbon chain molecules. The present theoretical results are certainly consistent with recent experimental results. Moreover, the encapsulation of C(10) makes an SWNT a (purely carbon-made) p-type acceptor. Another interesting possibility associated with the present system is the direction-controlled transport of C(10)H inside an SWNT under an external field. Because C(10)H has an electric dipole moment, it is expected to move under a gradient electric field. Finally, we derive the entropies of linear chain molecules inside and outside an open-ended SWNT to discuss the stability of including linear chain molecules inside an SWNT at finite temperatures. PMID:21542616

Kuwahara, Riichi; Kudo, Yohei; Morisato, Tsuguo; Ohno, Kaoru

2011-05-26

353

Surface-enhanced Raman scattering of single-walled carbon nanotubes on silver-coated and gold-coated filter paper  

Microsoft Academic Search

Surface-enhanced Raman scattering (SERS) spectra of single-walled carbon nanotubes (SWCNTs) on metal-coated filter paper are reported for the first time. Experimental results show that the metal-coated filter paper is very effective and active. The SERS spectrum not only shows that all Raman bands of SWCNTs in normal Raman scattering have been generally enhanced, but also shows many new bands, which

Zhiqiang Niu; Yan Fang

2006-01-01

354

Chemical vapor deposition growth of single-walled carbon nanotubes with controlled structures for nanodevice applications.  

PubMed

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 ratio of s-SWNT arrays. We also designed a smart scotch tape to sort out the s-SWNTs and m-SWNTs from the as-grown mixture with 3-aminopropyl-triethoxysilane and triethoxyphenylsilane as glues, respectively. This is analogous to the mechanical exfoliation of a graphene sheet. Third, the obtained SWNT intramolecular junctions obtained by temperature-mediated CVD indicate that temperature can seriously affect the SWNT's chirality during its growth. Importantly, the cloning method can validate the chirality-controlled growth of SWNTs, and the cloning efficiency is significantly improved on a quartz surface. Well-aligned SWNT arrays with a high density and controlled structures are highly desirable for carbon nanoelectronics. We hope that the advanced methodology used here will promote their controlled preparation and provide insights into the growth mechanism of SWNTs. PMID:24926610

Chen, Yabin; Zhang, Jin

2014-08-19

355

Fabrication, characterization and modeling of single-walled carbon nanotube films for device applications  

NASA Astrophysics Data System (ADS)

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 contacts on GaAs and Si were extracted by measuring the dark I-V characteristics in the thermionic emission regime. The extracted barrier heights corresponded to a CNT film workfunction of about ˜ 4.6 eV, which was in excellent agreement with previously reported values.

Behnam, Ashkan

356

Nerve agent detection using networks of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

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.

Novak, J. P.; Snow, E. S.; Houser, E. J.; Park, D.; Stepnowski, J. L.; McGill, R. A.

2003-11-01

357

Nanoscopically flat open-ended single-walled carbon nanotube substrates for continued growth.  

PubMed

Continued growth is a way of growing nanotubes targeted to produce continuous and chirality-controlled single-walled carbon nanotube (SWNT) materials. This growth method strongly depends on efficient preparation of open-ended SWNT substrates. Nanoscopically flat open-ended SWNT substrates have been prepared by cutting the SWNT spun fiber with a focused ion beam cutting technique and followed by etching schemes for cleaning amorphous carbon and opening the ends of the SWNTs. The open ends were effectively characterized through selective etch back of open SWNT ends by carbon dioxide gas at 950 degrees C. High density continued growth was demonstrated from these nanoscopically flat open-ended substrates. PMID:17212433

Kim, Myung Jong; Haroz, Erik; Wang, Yuhuang; Shan, Hongwei; Nicholas, Nolan; Kittrell, Carter; Moore, Valerie C; Jung, Yeonwoong; Luzzi, David; Wheeler, Robert; BensonTolle, Tia; Fan, Hua; Da, Sean; Hwang, Wen-Fang; Wainerdi, T J; Schmidt, Howard; Hauge, Robert H; Smalley, Richard E

2007-01-01

358

XPS Protocol for the Characterization of Pristine and Functionalized Single Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

Sosa, E. D.; Allada, R.; Huffman, C. B.; Arepalli, S.

2009-01-01

359

Purification of Single Wall Carbon Nanotubes as a Function of UV Wavelength, Atmosphere, and Temperature  

SciTech Connect

We investigate the purification of as-prepared single wall carbon nanotubes (SWCNTs) by exposure to pulsed 193 and 248 nm laser light, as well as lamp wavelengths of 254 and 185 nm. Raman spectroscopy before and after laser exposure indicates the removal of non-nanotube material without modification of the distribution of tube diameter for material exposed to a 248 nm laser, while 193 nm laser light does not selectively oxidize carbon impurities. The mechanism of purification is further considered in the context of atmosphere (oxygen, ozone, nitrogen or partial vacuum) and temperature (measured average and calculated maximum). A mathematical model for pulsed laser heating is used to estimate the maximum temperature achieved during laser excitation. We attribute the purification of nanotube samples to photophysical interactions of the pulsed 248 nm photons in resonance with sp{sup 2} carbon.

Kurst, K. E.; Dillon, A. C.; Yang, S.; Lehman, J. H.

2008-01-01

360

Evolution of the Catalyst Nanoparticles during CVD Growth of Carbon Single-Walled Nanotubes  

NASA Astrophysics Data System (ADS)

Despite intense studies, the growth mechanism of carbon single- walled nanotubes (SWNTs) is still debated and current synthesis methods do not allow for full control over the growth. There has been much discussion of whether the active catalytic species are in the liquid or solid phase during SWNTs formation, which is a key to understand and to control the growth of these materials. However, the actual phase of the catalyst and its evolution during carbon SWNTs growth still has to be experimentally verified. We report the observation of carbon induced solid-liquid and solid--liquid-solid phase transitions of the iron nanocatalyst during the synthesis, using differential scanning calorimetry and Raman scattering measurements. We found that as long as the nanocatalyst is in a liquid state, SWNTs growth occurs and continues until its solidification. Moreover, no growth was observed below the eutectic point, when the catalyst is always in solid phase.

Mora, Elena; Tokune, Toshio

2005-03-01

361

Structural stability of transparent conducting films assembled from length purified single-wall carbon nanotubes  

SciTech Connect

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.

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

362

Novel method to produce single-walled carbon nanotube films and their thermal and electrical properties.  

PubMed

Single-walled carbon nanotube films are promising candidates for applications requiring transparent conductors due to their low sheet resistance and high transparency in the visible region. Vacuum filtration is a common and easy to implement technique to produce such films but it is complicated by the need to transfer the films to desired substrates. Here we report conditions under which single-walled carbon nanotube films produced by vacuum filtration detach from the filter membrane upon submersion into water, providing a facile method to transfer filtration-produced nanotube films to desired substrates. Sheet resistance and transparency measurements show that these films are competitive with other high conductivity films made through more cumbersome procedures. Films post-treated with nitric acid or made with acid pre-treated nanotubes have superior performance to those made with high-purity nanotubes without any acid treatment. Thermal imaging by scanning thermal microscopy indicates that heat dissipation by the film is comparable to that of a glass substrate. PMID:21121309

Jakubinek, Michael B; Johnson, Michel B; White, Mary Anne; Guan, Jingwen; Simard, Benoit

2010-12-01

363

Air separation by single wall carbon nanotubes: Mass transport and kinetic selectivity  

NASA Astrophysics Data System (ADS)

Mass transport of pure nitrogen, pure oxygen, and their mixture (air) has been studied at 100 K in a single wall carbon nanotube of 12.53 Å diameter. Phenomenological coefficients, and self- and corrected diffusivities are calculated using molecular-dynamics simulations, and transport diffusivities are obtained by combining these results with thermodynamic factors obtained from previous grand canonical Monte Carlo simulations [G. Arora and S. I. Sandler, J. Chem. Phys. 123, 044705 (2005)]. For mixtures, cross-term diffusion coefficients are found to be of similar order of magnitude as main-term diffusion coefficients over the entire range of pressure studied. These results are then combined with a continuum description of mass transport to determine the ideal and kinetic separation factors for a nanotube membrane. High permeances are observed for both pure components and the mixture inside the nanotubes. The concentration profiles, diffusivity profiles, and membrane fluxes are calculated, and it is demonstrated that by carefully adjusting the upstream and downstream pressures, a good kinetic selectivity can be achieved for air separation using single wall carbon nanotubes.

Arora, Gaurav; Sandler, Stanley I.

2006-02-01

364

Water at nanoscale confined in single-walled carbon nanotubes studied by NMR  

NASA Astrophysics Data System (ADS)

Proton NMR studies have been carried out as a function of temperature from 210 K to 300 K on water confined within single-walled carbon nanotubes. The NMR lineshape at and below the freezing point of bulk water is asymmetric and can be decomposed into a sum of two Lorentzians. The intensities of both the components decrease with the lowering of the temperature below 273 K, one component, L1, vanishing below 242 K and the other component, L2, below 217 K. Following the simulations of Koga et al. showing that the radial density profile of confined water in single-wall carbon nanotubes has a distribution peak at the center which disappears below the freezing temperature, the L1-component is associated with the protons of the water molecules at the center and the L2-component is associated with protons of water molecules at a distance of ~ 3 Å from the walls of the nanotubes. In this scenario the complete freezing of the water at ~ 212 K is preceded by the withdrawal of the water molecules from the center.

Ghosh, S.; Ramanathan, K. V.; Sood, A. K.

2004-03-01

365

Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells  

PubMed Central

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 ?g/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 ?g/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 ?g/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.

2011-01-01

366

Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells  

NASA Astrophysics Data System (ADS)

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 ?g/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 ?g/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 ?g/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.

Yuan, Hengguang; Hu, Shanglian; Huang, Peng; Song, Hua; Wang, Kan; Ruan, Jing; He, Rong; Cui, Daxiang

2011-12-01

367

Adsorption kinetics of Escherichia coli and Staphylococcus aureus on single-walled carbon nanotube aggregates.  

PubMed

Batch adsorption studies to determine adsorption kinetics of Escherichia coli (E.coli) K12 and Staphylococcus aureus (S.aureus) SH 1000 bacterial cells on single-walled carbon nanotube aggregates were performed at two different initial concentrations. The diffusivity of E. coli cells in single-walled carbon nanotube aggregates obtained was 6.54 x 10(-9) and 8.98 x 10(-9) cm(2)/s, whereas that of S. aureus was between 1.00 x 10(-7) and 1.66 x 10(-7) cm(2)/s respectively. In addition to batch adsorption studies, electron microscopy studies were also conducted. The results suggest that diffusion kinetics of bacterial cells is concentration dependent as well as bacteria dependent. Diffusivity of S. aureus is two orders of magnitude greater than E. coli cells. This proves to be beneficial from an adsorption perspective where it is desired to filter microorganisms (water pretreatment and wastewater post treatment) and from nanotube biosensor perspective where it is desired to simultaneously capture and detect biothreat agents in a shorter span of time. PMID:18653952

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

2008-01-01

368

Growth of all-carbon horizontally aligned single-walled carbon nanotubes nucleated from fullerene-based structures  

PubMed Central

All-carbon single-walled carbon nanotubes (SWCNTs) were successfully synthesized, nucleated using a fullerene derivative. A systematic investigation into the initial preparation of C60 fullerenes as growth nucleators for the SWCNTs was conducted. Enhancement in the yield of the produced SWCNT has been achieved with exploring different dispersing media for the fullerenes, the period, and environment of the initial thermal treatment of the fullerenes in addition to the use of different fullerene-based structures. The systematic studies significantly advance our understanding of the growth of the all-carbon catalyst-free single-walled carbon nanotubes. Field-effect transistors were fabricated using the catalyst-free SWCNT and then electrically characterized, showing current capacity as high as the well-studied catalyst-assisted nanotubes. PMID:23742117

2013-01-01

369

Functionalization of single-walled carbon nanotubes regulates their effect on hemostasis  

NASA Astrophysics Data System (ADS)

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.

Sokolov, A. V.; Aseychev, A. V.; Kostevich, V. A.; Gusev, A. A.; Gusev, S. A.; Vlasova, I. I.

2011-04-01

370

Development of novel single-wall carbon nanotube epoxy composite ply actuators  

NASA Astrophysics Data System (ADS)

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.

Yun, Yeo-Heung; Shanov, Vesselin; Schulz, Mark J.; Narasimhadevara, Suhasini; Subramaniam, Srinivas; Hurd, Douglas; Boerio, F. J.

2005-12-01

371

Optical and electrical studies of single walled carbon nanotubes for infrared sensing and photovoltaic applications  

NASA Astrophysics Data System (ADS)

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 with phosphorous oxy and carbonyl groups. According to the time dependent current-voltage measurements, the differential conductance, G, of the nanotubes varies with temperature given by G ˜ T? , with ? exhibiting a slight increase as a result of the treatment, attributed to a slight increase in the role of disorder. The nanotubes processed for three hours are also found to show an order of magnitude improvement in their photoconduction response time compared to untreated nanotubes, with their growth and decay characteristic time constants being in the sub-second range.

Omari, Mones A.

372

In vivo MRI of single-wall carbon nanohorns through magnetite nanoparticle attachment  

NASA Astrophysics Data System (ADS)

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.

Miyawaki, Jin; Yudasaka, Masako; Imai, Hideto; Yorimitsu, Hideki; Isobe, Hiroyuki; Nakamura, Eiichi; Iijima, Sumio

2006-03-01

373

Fabrication and performance of contamination free individual single-walled carbon nanotube optical devices.  

PubMed

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

Zhou, Yuxiu; Cheng, Rong; Liu, Jianqiang; Li, Tie

2014-06-01

374

Resistance in single-walled carbon nanotube networks formed on gold nanoparticle templates  

NASA Astrophysics Data System (ADS)

The temperature dependence features of a typical intrinsic semiconductor resistance were used to study the resistances in single-walled carbon nanotube (SWNT) networks formed on gold nanoparticle (AuNP) templates, using the resistance-temperature relations in the temperature range from 440 to 570 K. The SWNTs were synthesized using the chemical vapour deposition method, with ethanol as a carbon source and cobalt particles as the catalyst. The synthesis was performed at 1073 K, for a duration of 60 min. It was found that the negative temperature coefficients and the energy gaps, which indicated the degree of semiconductor behaviour, increased with increasing sample starting resistance. However, at the same sample starting resistance, the degree of semiconductor behaviour increased with increasing AuNP number density, resulted from the change in the effective diameter of the semiconducting SWNTs of the sample, which occurred because of the effects of the AuNP number density.

Wongsaeng, Chalao; Singjai, Pisith

2013-06-01

375

Calculation of diffusion coefficients of water and alkanes through single-walled carbon nanotubes from simulations  

SciTech Connect

Recent experimental work has shown that membranes containing aligned carbon nanotubes exhibit transport rates for gases and liquids that are orders of magnitude larger than rates predicted from Knudsen or hydrodynamic no-slip flow. We present atomically detailed simulations of diffusion of water and alkanes through single-walled carbon nanotubes. The self, corrected, and transported diffusivities are calculated for liquid-like densities of water and alkanes in nanotubes using equilibrium molecular dynamics, with thermodynamic correction factors computed from Monte Carlo adsorption isotherm calculations. We also present the zero-coverage diffusivities for these fluids. We discuss the results in comparison with bulk fluid self-diffusivities and experimental data for flow through nanotubes membranes.

Johnson, J.K.; Wang, Y.; Liu, J.-C.; Sholl, D.S.

2007-08-01

376

Detecting Lyme Disease Using Antibody-Functionalized Single-Walled Carbon Nanotube Transistors  

E-print Network

We examined the potential of antibody-functionalized single-walled carbon nanotube (SWNT) field-effect transistors (FETs) for use as a fast and accurate sensor for a Lyme disease antigen. Biosensors were fabricated on oxidized silicon wafers using chemical vapor deposition grown carbon nanotubes that were functionalized using diazonium salts. Attachment of Borrelia burgdorferi (Lyme) flagellar antibodies to the nanotubes was verified by Atomic Force Microscopy and electronic measurements. A reproducible shift in the turn-off voltage of the semiconducting SWNT FETs was seen upon incubation with Borrelia burgdorferi flagellar antigen, indicative of the nanotube FET being locally gated by the residues of flagellar protein bound to the antibody. This sensor effectively detected antigen in buffer at concentrations as low as 1 ng/ml, and the response varied strongly over a concentration range coinciding with levels of clinical interest. Generalizable binding chemistry gives this biosensing platform the potential to...

Lerner, Mitchell B; Goldsmith, Brett R; Brisson, Dustin; Johnson, A T Charlie

2013-01-01

377

Structure and Properties of poly (para phynelyne benzobisoxazole) (PBO) /single wall carbon nano tube composite fibers  

NASA Astrophysics Data System (ADS)

The liquid crystalline compositions are prepared by the in-situ polycondensation of diamines and diacid monomers in the presence of single wall carbon nano tubes (SWNT). Processing of the new compositions into fibers provide hybrid materials with improved mechanical properties. The in-situ polymerizations were carried out in polyphosphoric acid (PPA). Carbon nano tubes as high as 10 wt.polymer weight have been utilized. Fiber spinning has been carried out using dry jet wet spinning using a piston driven spinning system and the fiber coagulated in water and subsequently vacuum dried and heat treated in nitrogen at 400oC. Structure and properties of these fibers have been studied. Tensile strength of the composite fibers increased by about 50morphology of these fibers have been studied using X- ray diffraction and scanning electron microscopy.

Kumar, Satish; Zhang, Xiefei; Bhattacharyya, Arup R.; Min, Byung G.; Dang, T. D.; Arnold, F. E.; Vaia, Richard A.; Ramesh, S.; Willis, P. A.; Hauge, R. H.; Smalley, R. E.

2002-03-01

378

Chiral selectivity in the charge-transfer bleaching of single-walled carbon-nanotube spectra  

NASA Astrophysics Data System (ADS)

Chiral selective reactivity and redox chemistry of carbon nanotubes are two emerging fields of nanoscience. These areas hold strong promise for producing methods for isolating nanotubes into pure samples of a single electronic type, and for reversible doping of nanotubes for electronics applications. Here, we study the selective reactivity of single-walled carbon nanotubes with organic acceptor molecules. We observe spectral bleaching of the nanotube electronic transitions consistent with an electron-transfer reaction occurring from the nanotubes to the organic acceptors. The reaction kinetics are found to have a strong chiral dependence, with rates being slowest for large-bandgap species and increasing for smaller-bandgap nanotubes. The chiral-dependent kinetics can be tuned to effectively freeze the reacted spectra at a fixed chiral distribution. Such tunable redox chemistry may be important for future applications in reversible non-covalent modification of nanotube electronic properties and in chiral selective separations.

O'Connell, Michael J.; Eibergen, Ezra E.; Doorn, Stephen K.

2005-05-01

379

High structural stability of single wall carbon nanotube under quasi-hydrostatic high pressures  

SciTech Connect

In quasi-hydrostatic conditions, single wall carbon nanotubes (SWNTs) exhibit high structural stability to {approx}35 GPa, well beyond the stability of sp{sup 2} C{double_bond}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 sp{sup 3} hybridization ({approx}20%) and, thus, increases the stability of sp{sup 2} C{double_bond}C bonds in the SWNTs.

Chen, Jing-Yin; Kim, Minseob; Yoo, Choong-Shik; (WSU)

2009-11-23

380

Terahertz generation and chaotic dynamics in single-walled zigzag carbon nanotubes.  

PubMed

We study self-sustained terahertz current oscillation and chaotic dynamics in semiconducting single-walled zigzag carbon nanotubes using the time-dependent drift diffusion equations. The current oscillation under a dc voltage bias originates from the negative differential velocity of carbon nanotube which induces the motion and recycling of unstable domain. Numerical simulation indicates that different nonlinear oscillatory modes appear when an external high-frequency ac voltage is superimposed to the dc voltage bias and its driving amplitude varies. The appearance of different nonlinear oscillating modes, including periodic and chaotic, is attributed to the competition between the natural oscillation and the external driving oscillation. The transitions between periodic and chaotic states are carefully studied using chaos-detecting methods, such as bifurcation diagram, phase portraits, first return map, and Fourier spectrum. The resulting bifurcation diagram displays an interesting and complex transition picture with the driving amplitudes as the control parameter. PMID:19792016

Wang, C; Cao, J C

2009-09-01

381

Self-built tensile strain in large single-walled carbon nanotubes.  

PubMed

Abnormal Raman scattering from a large-diameter ultralong single-walled carbon nanotube (SWCNT) is studied in detail. Along the SWCNT, the Raman spectra show the frequencies of 1553, 1563, and 2597 cm(-1) for G(+), G(-), and G' peaks, respectively, much lower than the corresponding frequencies well-reported both experimentally and theoretically. The significant downshifts in the peaks frequencies can be attributed to self-built tensile strain, which is likely caused by carbon nanodots decorated on the tube. After infrared laser heating is performed to one point of it, all of the Raman modes are found to shift to higher frequencies and approach their conventional values. We suggest that the SWCNTs with larger diameters easily possess such self-built strain compared to small-diameter SWCNTs because of the weaker curvature effect for the larger ones. PMID:20078093

Gao, Pingqi; Zheng, Lianxi; Zhang, Qing; Yuan, Shaoning; You, Yumeng; Shen, Zexiang; He, Deyan

2010-02-23

382

Adsorption equilibrium of organic vapors on single-walled carbon nanotubes  

USGS Publications Warehouse

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.

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

2005-01-01

383

Radial breathing mode of single-walled carbon nanotubes: Optical transition energies and chiral-index assignment  

E-print Network

, in fundamental studies we want to know which nano- tube is probed experimentally. The growth of carbon nanoRadial breathing mode of single-walled carbon nanotubes: Optical transition energies and chiral of carbon nanotubes in aqueous suspen- sions by resonant Raman scattering of the radial breathing mode. We

Nabben, Reinhard

384

Separation of Single-Walled Carbon Nanotubes with DEP-FFF  

NASA Technical Reports Server (NTRS)

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 spectrum and visible absorption spectrums simultaneously. Dielectrophoresis field-flow fractionation (DEP-FFF) generally depends on interaction of a sedimentation force and DEP force for particle separation, and SWNTs are neutrally buoyant in water. In this innovation, the third electrode was added to create a sedimentation force based on DC electrophoresis. This makes this particular device applicable to separations on any neutrally buoyant particles in solution and a more general process for a broad range of nanomaterials sorting and separations.

Schmidt, Howard K.; Peng, Haiqing; Alvarez, Noe; Mendes, Manuel; Pasquali, Matteo

2011-01-01

385

Single-walled metal oxide nanotubes and nanotube membranes for molecular separations  

NASA Astrophysics Data System (ADS)

Single-walled nanotubes have been considered essential “building-blocks” in nanotechnology and emerging materials for molecular recognition-based applications, such as molecular sensing, catalysis, and separations. Two critical obstacles in the development of functional nanotube-based devices are: (a) the difficulty of creating diverse functionality at the interior surfaces of single-walled nanotubes, and (b) the lack of effective approaches for fabricating scalable technological platforms with nanotube materials. This thesis describes my work addressing key fundamental issues in nanotube science and technology; particularly regarding the synthesis, characterization, and functionalization of single-walled metal oxide nanotubes (SWNTs) (Chapters 2, 3, 4),and approaches for applying SWNTs in scalable separation platforms for potentially achieving high performance (Chapters 5, 6, 7). The above, rather ambitious, objectives were addressed in a step-wise manner in this work. First, I acquired a detailed fundamental understanding of the inner surface properties of aluminosilicate SWNTs (Chapter 2). The investigations included elucidating molecular level details of dehydration and dehydroxylation phenomena in aluminosilicate single-walled nanotubes with a combination of several temperature-dependent solid-state characterization techniques. Critical information from this study enables a number of subsequent processes such as interior modification, molecular transport, and controlled delivery of molecules. In Chapter 3, a successful post-synthesis interior functionalization methodology is discussed, with the appropriately dehydrated or dehydroxylated nanotubes as the starting materials. Through surface reactions involving organosilane precursors and the inner wall of the nanotube, diverse organic entities can be immobilized at the inner surface of aluminosilicate nanotubes and thereby the hydrophilicity and interior surface properties can be tailored. This study was the first unambiguous demonstration of covalent modification of the interior of single-walled nanotube materials. The investigations in Chapter 4 reveal a direct (in situ) route for synthesizing organic-functionalized alumino-silicate nanotubes via the use of organosilanes with functional groups in the synthesis itself (as opposed to post-synthesis modification). This work creates a one-step route for the incorporation of functional groups at the interior of nanotubes, thus bypassing the limitations of the low functional group loading as well as additional processing steps in the post-synthesis functionalization methodology of Chapter 3. The two functionalization methods developed (post-synthesis and direct functionalization) together may enable a range of applications of nanotube materials, including separations, catalysis, and molecular capture/encapsulation/storage. The direction of the work then turned to the fabrication of nanotube-containing membranes. In view of the absence of a good predictive model for the performance of nanotube-containing membranes, Chapter 5 describes the development of analytical models for quantitatively predicting the separation properties of composite membranes containing (nano)tubular fillers. These models provide useful guidance for evaluating/optimizing existing nanotube-based membranes as well as preparing nanotube-based membranes with novel device architectures and enhanced separation performance. In Chapter 6, the fabrication and characterization of free-standing nanotube/ polymer composite membranes with good organic-inorganic interface adhesion and good nanotube dispersion is discussed. A detailed investigation of the structure and propreties of these membranes (at nano-, micro-, and macro- length scales) is presented. It is shown that hese nanocomposite membranes could be effectively used to construct scalable membrane separation devices. This work is the first demonstration of a defect-free membrane containing well-dispersed nanotube materials. Molecular level insights on the morphological changes of polymer chains due to

Kang, Dun-Yen

386

Semiconducting single-walled carbon nanotubes sorting with a removable solubilizer based on dynamic supramolecular coordination chemistry.  

PubMed

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. PMID:25277810

Toshimitsu, Fumiyuki; Nakashima, Naotoshi

2014-01-01

387

Semiconducting single-walled carbon nanotubes sorting with a removable solubilizer based on dynamic supramolecular coordination chemistry  

NASA Astrophysics Data System (ADS)

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.

Toshimitsu, Fumiyuki; Nakashima, Naotoshi

2014-10-01

388

Hexafluorobisphenol A covalently functionalized single-walled carbon nanotubes for detection of dimethyl methylphosphonate vapor.  

PubMed

Hexafluorobisphenol A (6FBPA), as a novel nerve agents sensing molecule, has been successfully attached onto the surface of single-walled carbon nanotubes (SWNTs). The sensing groups have been confirmed by infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectrometry. The results revealed that the sensing groups had been successfully anchored on the surface of nanotubes. The quantitative determination of the functional groups has also been carried out through characterization by thermogravimetric analysis. Furthermore, the morphology of the resultant SWNT-6FBPA hybrids has been observed by transmission electron microscopy and scanning electron microscopy. Due to the existence of phenolic hydroxyl groups, which can form strong hydrogen-bonding with dimethyl methylphosphonate (DMMP) (simulant of nerve agent sarin), the functionalized SWNTs showed excellent sensitivity and selectivity while the sensing devices have been fabricated. PMID:21770116

Wang, Yanyan; Wang, Zi; Hu, Nantao; Wei, Liangming; Xu, Dong; Wei, Hao; Kong, Eric Siu-Wai; Zhang, Yafei

2011-06-01

389

Phases of ethane adsorbed on purified HiPco single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We have used adsorption isotherms to study ethane films on bundles of purified HiPco single-walled carbon nanotubes (SWNTs). We infer the existence of a possible phase transition in this system from a sudden change in the temperature dependence of the coverage interval corresponding to a feature present in the isotherms. The possible phase transition occurs near monolayer completion, at approximately 110K . We also measured isotherms at low fractional coverages and relatively high temperatures (220-240K) in order to determine the binding energy of ethane on the SWNT bundles. We obtained a value of 308meV for this quantity; this is 1.76 times larger than the binding energy of ethane on graphite. We used isotherm results obtained at all measured temperatures and coverages to determine the coverage dependence of the isosteric heat of adsorption for this system.

Rawat, Dinesh S.; Migone, Aldo D.

2007-05-01

390

Photodynamic effect of functionalized single-walled carbon nanotubes: a potential sensitizer for photodynamic therapy  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) possess unique physical and chemical properties, which make them very attractive for a wide range of applications. In particular, SWNTs and their composites have shown a great potential for photodynamic therapy (PDT). SWNTs have usually been used for photothermal therapy; herein, the photodynamic effect of two functionalized SWNTs are detected under visible light illumination in vitro and in vivo. The results indicated that the photodynamic effect is not entirely dependent on illumination time, but also on the modification method of the SWNTs. The ability of SWNTs complexes to combine with photodynamic therapy significantly improved the therapeutic efficacy of cancer treatment, and the combined treatment demonstrated a synergistic effect. These findings suggest that the SWNTs composite has great potential as sensitizer for PDT.

Wang, Lei; Shi, Jinjin; Liu, Ruiyuan; Liu, Yan; Zhang, Jing; Yu, Xiaoyuan; Gao, Jun; Zhang, Chaofeng; Zhang, Zhenzhong

2014-04-01

391

Charge Manipulation in Molecules Encapsulated Inside Single-Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We report clear experimental evidence for the charge manipulation of molecules encapsulated inside single-wall carbon nanotubes (SWCNTs) using electrochemical doping techniques. We encapsulated ?-carotene (Car) inside SWCNTs and clarified electrochemical doping characteristics of their Raman spectra. C=C streching modes of encapsulated Car and a G band of SWCNTs showed clearly different doping behaviors as the electrochemical potentials were shifted. Electron extraction from encapsulated Car was clearly achieved. However, electrochemical characteristics of Car inside SWCNTs and doping mechanisms elucidated by calculations based on density-functional theory indicate the difficulty of charge manipulation of molecules inside SWCNTs due to the presence of strong on-site Coulomb repulsion energy at the molecules.

Yanagi, Kazuhiro; Moriya, Rieko; Cuong, Nguyen Thanh; Otani, Minoru; Okada, Susumu

2013-02-01

392

Effects of Single Walled Carbon Nanotubes on the Electroluminescent Performance of Organic Light-emitting Diodes  

SciTech Connect

Effects of single walled carbon nanotubes (SWNTs) on the electroluminescent performance of organic light-emitting diodes (OLEDs) have been investigated by mixing them in a hole-conducting layer and in a light-emitting layer in OLEDs. We found that SWNTs play different roles when used as polymer:SWNT composites in OLEDs. When used in a hole-conducting layer, SWNTs facilitate the charge transport in the transport layer and on the other hand they also act as the exciton quenching centers at the transporting/emitting interface provided their concentration is high enough. When used in a light-emitting layer, SWNTs act as an n-type dopant to increase electron transport in p-type electroluminescent film and subsequently improve the balancing degree of bipolar injection, leading to an enhancement in the electroluminescence efficiency.

Wong, S.S.; Shao, M.; Garrett, M.P.; Xu, X.; Ivanov, I.N.; Hu, B.

2011-06-01

393

Characterization of Single-Walled Carbon Nanotubes with Nodal Structural Defects  

E-print Network

Recently experiments showed that nodal structural defects are readily formed in the synthesis of single-walled carbon nanotubes (SWNTs) and consequently, SWNTs are likely to deviate from well-defined seamless tubular structures. Here, using graphene-helix growth model, we describe structural details of feasible nodal defects in SWNTs and investigate how mechanical and electronic properties of SWNTs would change in the presence of them using computational methods. Surprisingly atomistic simulations of SWNTs with nodal defects show excellent agreement with previous structural, tensile, and ball-milling experiments whose results cannot be explained using conventional models. The tensile failure of SWNTs with nodal defects requires about four- or six-fold lower strength than pristine ones and these SWNTs are comparatively prone to damage under a lateral compressive biting. We reveal that electronic band-gap of SWNT(12,8) would be remarkably reduced in the presence of nodal defects. This study strongly indicates u...

Jhon, Young I; Lee, Seok; Jhon, Young Min

2014-01-01

394

Precise determination of the threshold diameter for a single-walled carbon nanotube to collapse.  

PubMed

Closed-edged bilayer graphene nanoribbons were formed by the spontaneous collapse of large-diameter single-walled carbon nanotubes (SWNTs) grown on gold nanoparticles by chemical vapor deposition. Such bilayer graphene nanoribbons could adopt different stacking configurations, such as AB-stacking or stacking order with any rotation angle, correlated with the chiral angles of their parent rounded SWNTs. On the basis of the electron diffraction characterizations on a good number of collapsed and uncollapsed SWNTs, the threshold diameter for SWNTs to collapse was precisely determined to be 5.1 nm, independent of the chiral angle of the SWNTs. The determination is consistent with that calculated by both classical adaptive intermolecular reactive empirical bond order force field and density functional theory after having taken the stacking effect and thermal fluctuation into account. PMID:25131158

He, Maoshuai; Dong, Jichen; Zhang, Kaili; Ding, Feng; Jiang, Hua; Loiseau, Annick; Lehtonen, Juha; Kauppinen, Esko I

2014-09-23

395

Fabrication of single-walled carbon nanohorns containing iodine and cesium  

SciTech Connect

Iodine and cesium atoms were encapsulated in single-walled carbon nanohorns (SWCNHs). Atom encapsulation was carried out with sequential plasma aided procedures which consisted of opening SWCNH tips with an oxygen plasma, atom insertion in an iodine-mixed or cesium-mixed argon plasma, and closing the open tip in an argon plasma. Results reveal that oxidation plays a role in the tip opening procedure, and capillary forces are the driving force for the permeation of the atoms through the open tip of the SWCNHs. The open tip of the atom inserted SWCNH can be closed under the ion irradiation. It demonstrated the fabrication process of encapsulating atoms in SWCNH by using the sequential plasma assisted processes.

Cho, J. H.; Lim, S. T.; Huh, S. R.; Kim, G. H. [Department of Nuclear Engineering, Seoul National University, Seoul, 151-741 (Korea, Republic of)

2012-02-15

396

Exciton Radiative Lifetimes and Their Temperature Dependence in Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We have investigated the radiative lifetimes of excitons in single-walled carbon nanotubes (SWNTs) from simultaneous measurements of the photoluminescence (PL) lifetimes [1] and the PL quantum yields. A high-quality sample of PFO dispersed-SWNTs was used for the PL measurements. The evaluated radiative lifetimes were ˜5-15 ns for SWNTs with diameters ˜0.8-1.1 nm at room temperature. The radiative lifetimes increased with the tube diameter. The exciton spatial coherence volume (length) was of the order 10 ^2 nm along the tube axis, as deduced from the radiative lifetimes. Furthermore, we discuss the dynamics of bright and dark excitons [2] from the temperature dependence of the radiative lifetime (10 to 300 K).[3pt] [1] H. Hirori, K. Matsuda, Y. Miyauchi, S. Maruyama, and Y. Kanemitsu, Phys. Rev. Lett. 97, 257401 (2006). [0pt] [2] R. Matsunaga, K. Matsuda, and Y. Kanemitsu, Phys. Rev. Lett. 101, 147404 (2008).

Miyauchi, Yuhei; Matsunaga, Ryusuke; Hirori, Hideki; Matsuda, Kazunari; Kanemitsu, Yoshihiko

2009-03-01

397

Electrical and mechanical characterisation of single wall carbon nanotubes based composites for tissue engineering applications.  

PubMed

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

Whulanza, Yudan; Battini, Elena; Vannozzi, Lorenzo; Vomero, Maria; Ahluwalia, Arti; Vozzi, Giovanni

2013-01-01

398

Non-radiative Exciton Decay in Single-walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Experiments have shown step-wise changes in the fluorescence intensity from single-walled carbon nanotubes [1,2]. It has been proposed that the underlying mechanism for the step-wise changes is diffusion-limited quenching of excitons at defects [1]. This property has been used to demonstrate single-molecule detection for biological applications [3]. We perform a Monte-Carlo simulation of nanotube fluorescence with a diffusion-limited quenching model. The fluorescence intensity is seen to depend on the mean-square distance between defects, implying a nonlinear dependence on the number of defects. The intensity for consecutive defect counts can overlap depending on the positions of the defects. [4pt] [1] Cognet, L. et al. Science 316, 1465-1468 (2007).[0pt] [2] Jin, H. et al. Nano Lett. 8, 4299-4304 (2008).[0pt] [3] Heller, D. A. et al. Nature Nanotech. 4, 114-120 (2009).

Harrah, Mark; Swan, Anna

2010-03-01

399

Immunoassay with single-walled carbon nanotubes as near-infrared fluorescent labels.  

PubMed

The intrinsic photoluminescence of single-walled carbon nanotubes (CNTs) in the near-infrared (NIR) above 1000 nm makes them promising candidates for biological probes owing to low interference by bioorganic molecules and deep tissue penetration. We here demonstrate an immunoassay by using a NIR CNT labels conjugated to immunoglobulin G (IgG) antibodies. Most of the CNT-conjugated IgG was successfully immunoprecipitated with protein G-attached magnetic beads and eluted from them, which was confirmed by the NIR emission of the conjugated CNTs at 1000-1200 nm. The photoluminescence intensity of the CNT labels was strong enough to detect antigens at 600 pM by our simple procedures. PMID:23927721

Iizumi, Yoko; Okazaki, Toshiya; Ikehara, Yuzuru; Ogura, Mutsuo; Fukata, Shinsuke; Yudasaka, Masako

2013-08-28

400

Hybrid solar cells based on single-walled carbon nanotubes/Si heterojunctions.  

PubMed

Photovoltaic devices based on single-walled carbon nanotubes (SWNTs) and n-silicon heterojunctions have been fabricated by a spray deposition process. We provide direct evidence that nanotubes serve as an active photosensing material involved directly in the photon absorption process as well as contributing to charge separation, transport and collection. The characteristic band of the SWNT band in the photoconductivity spectrum matches the S(11) absorption band of semiconducting SWNTs of 7,6 chirality. Centrifugation of the SWNTs provides two fractions. The sediment fraction exhibits a conversion efficiency ( approximately 1.7%) higher by a factor of eight compared to the supernatant fraction. SEM images and conductivity measurements show that the SWNT network morphology of the sediment fraction has longer and thicker nanotube bundles forming highly porous films, accounting for the enhanced conductivity and higher transparency. PMID:20157233

Ong, Pang-Leen; Euler, William B; Levitsky, Igor A

2010-03-12

401

Photoinduced transient mid-infrared absorption in single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We have performed optical pump - mid-infrared (MIR) probe spectroscopy on single-walled carbon nanotubes (SWNTs). The second excitonic absorption band (E22) of (6,5) SWNTs was resonantly excited and the resulting photoinduced absorption was monitored in the MIR range (3.5 -- 5.5 ?m) in a time range up to several hundred ps. Carrageenan films containing individualized CoMoCAT SWNTs formed on sapphire substrates were used for the measurement. This sample is optically transparent in the ˜3.5 -- 6 ?m region, where the transition of E11 excitons from the lowest dark state (1g) to the second bright state (2u) is expected to be observed. Our preliminary data shows the existence of photoinduced absorption in the investigated range. The origin of the observed transient absorption will be discussed.

Murakami, Yoichi; Rice, William; Kono, Junichiro

2007-03-01

402

Novel Materials Containing Single-Wall Carbon Nanotubes Wrapped in Polymer Molecules  

NASA Technical Reports Server (NTRS)

In this design, single-wall carbon nanotubes (SWNTs) have been coated in polymer molecules to create a new type of material that has low electrical conductivity, but still contains individual nanotubes, and small ropes of individual nanotubes, which are themselves good electrical conductors and serve as small conducting rods immersed in an electrically insulating matrix. The polymer is attached through weak chemical forces that are primarily non-covalent in nature, caused primarily through polarization rather than the sharing of valence electrons. Therefore, the electronic structure of the SWNT involved is substantially the same as that of free, individual (and small ropes of) SWNT. Their high conductivity makes the individual nanotubes extremely electrically polarizable, and materials containing these individual, highly polarizable molecules exhibit novel electrical properties including a high dielectric constant.

Smalley, Richard E.; O'Connell, Michael J.; Smith, Kenneth; Colbert, Daniel T.

2009-01-01

403

Investigation of Aromatic/Aliphatic Polyimides as Dispersants for Single Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Novel aromatic/aliphatic polyimides were prepared from 2,7-diamino-9,9'- dioctylfluorene (AFDA) and aromatic dianhydrides. Upon investigating the effectiveness of these polyimides for dispersing single wall carbon nanotubes (SWNTs) in solution, three were discovered to disperse SWNTs in N,N-dimethylacetamide (DMAc). Two of these polyimides, one from 3,3',4,4'-oxydiphthalic anhydride (ODPA) and one from symmetric 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), were used to prepare nanocomposites. Homogeneous polyimide/SWNT suspensions from both polymers were used in the preparation of films and fibers containing up to 1 wt% SWNTs. The samples were thermally treated to remove residual solvent and the films were characterized for SWNT dispersion by optical and high resolution scanning electron microscopy (HRSEM). Electrical and mechanical properties of the films were also determined. Electrospun fibers were examined by HRSEM to characterize SWNT alignment and orientation.

Delozier, Donavon M.; Watson, Kent A.; Smith, Joseph G., Jr.; Clancy, Thomas C.; Connell, John W.

2006-01-01

404

Adsorption of nitro-substituted aromatics on single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Molecular adsorption of nitroaromatic molecules on single-walled carbon nanotubes (NTs) was investigated using state-of-the-art ab initio calculations and conductivity measurements. In the calculations we considered both armchair and zigzag NTs of several diameters and treated adsorption both on pristine sidewalls and oxygenated defects. The resulting adsorption energies on the pristine sidewalls were found to increase linearly with the number of NO2 groups and with the NT diameter. The adsorption mechanism is predominantly physisorption through ?-? stacking, with additional contributions from the NO2 groups. The calculated adsorption energies at oxygenated defects were found to be comparable with those on the pristine sidewall. In both cases the functional groups give rise to local electronic polarization and to shifts in vibrational lines due to small charge transfers. The dependence of adsorption energies on the number of NO2 groups was found to be consistent with conductivity measurements on NT arrays exposed to trace amounts of nitroaromatic derivatives.

Alldredge, E. S.; B?descu, ?. C.; Bajwa, N.; Perkins, F. K.; Snow, E. S.; Reinecke, T. L.

2010-09-01

405

Exciton size and mobility in (6,5) single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Using femtosecond pump probe spectroscopy with sub-20 fs resolution, we probe fundamental properties of the E11 exciton in (6,5) single walled carbon nanotubes, prepared by density gradient ultracentrifugation. From the initial photobleaching signal, measured faster than any relaxation process, we obtain the one-dimensional size of the excitonic wavefunction along the nanotube. Exciton decay is found pump-intensity dependent only at elevated pump intensities. Numerical modelling of decay kinetics yields an exciton diffusion coefficient of about 0.1 cm^2/s. Anisotropy measurements in highly purified samples show that there is virtually no depolarisation of the E11 bleach over 40 ps. A photoinduced absorption (PA) band, blueshifted against the E11 bleach, shows only weak anisotropy.

Lüer, Larry; Hoseinkhani, Sajjad; Polli, Dario; Crochet, Jared; Hertel, Tobias; Lanzani, Guglielmo

2008-04-01

406

Passively Q-switching induced by the smallest single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report a passively Q-switched erbium-doped fiber laser (EDFL) by using the smallest single-walled carbon nanotubes (SWNTs) with a diameter of 0.3 nm as the saturable absorber. These small SWNTs are fabricated in the nanochannels of a ZnAPO-11 (AEL) single crystal. By inserting one of the AEL crystal into an EDFL cavity pumped by a 980 nm laser diode, stable passive Q-switching is achieved for a threshold pump power of 206.2 mW, and 4.73 ?s pulses with a repetition rate of 41.78 kHz and an average output power of 3.75 mW are obtained for a pump power of 406 mW.

Xu, X. T.; Zhai, J. P.; Wang, J. S.; Chen, Y. P.; Yu, Y. Q.; Zhang, M.; Li, I. L.; Ruan, S. C.; Tang, Z. K.

2014-04-01

407

Theory of phonon thermal conductivity of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We have developed a Boltzmann transport approach to calculate the intrinsic lattice thermal conductivity of single-walled carbon nanotubes. Harmonic and anharmonic interatomic force constants are obtained from Brenner [1] and Tersoff [2] empirical potentials, while the full phonon Boltzmann equation is solved using an iterative scheme [3]. We employ symmetry based selection rules for anharmonic phonon-phonon scattering, and we include higher order anharmonicity in our examination of the phonon-phonon scattering for the acoustic modes. We compare our results to those obtained from other recent theoretical calculations [3, 4]. [1] D. Brenner et al., J. Phys. Condens. Matter 14, 783 (2002). [2] J. Tersoff, Phys. Rev. B 39, 5566 (1989). [3] N. Mingo and D. A. Broido, Nano Letters 5, 1221 (2005). [4] D. Donadio and G. Galli, Phys. Rev. Lett. 99, 25502 (2007).

Lindsay, L.; Broido, D. A.; Mingo, N.

2009-03-01

408

Hierarchical morphology of carbon single-walled nanotubes during sonication in an aliphatic diamine  

SciTech Connect

Dispersion of single-walled carbon nanotubes (SWNTs) by sonication into diamine curing agents is studied as a means to improve the dispersion of SWNTs in cured epoxy. Cured and uncured specimens are analyzed by light microscopy, electron microscopy, light scattering (LS), ultra small-angle X-ray scattering (USAXS), electrical conductivity and Raman spectroscopy. A flexible diamine (D2000) forms a stable SWNT suspension leading to good homogeneity in both the diamine and the cured epoxy. High resolution transmission electron microscopy (TEM) shows that small ropes of SWNTs (mostly under 15 nm) are present despite the sample's visual homogeneity. Further morphological investigation of cured and uncured D2000 resins using light and small-angle X-ray scattering indicates that the SWNTs are networked into fractal clusters that electrically percolate at low SWNTs loadings (0.05 wt%).

Brown, Janis M.; Anderson, David P.; Justice, Ryan S.; Lafdi, Khalid; Belfor, Max; Strong, Karla L.; Schaefer, Dale W. (UDRI); (UCIN); (AFRL)

2010-07-13

409

Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer  

NASA Astrophysics Data System (ADS)

We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

Jilili, Jiwuer; Abdurahman, Ayjamal; Gülseren, O?uz; Schwingenschlögl, Udo

2014-07-01

410

Raman spectra of lithium doped single-walled 0.4 nm carbon nanotubes  

NASA Astrophysics Data System (ADS)

Using the vapor phase adsorption method, we show that it is possible to intercalate lithium atoms into 0.4-nm diameter single-walled carbon nanotubes. The charge-transfer behavior is studied by resonant Raman spectra. With increasing doping concentration, the radial breathing mode of these tubes shifts to higher frequency by about 18 cm-1 because the vibration perpendicular to the tube axis is depressed. The G band exhibits conventional softening and downshift behavior. By decomposing the G band by one Breit-Wigner-Fano line shape and three Lorentzians, we found that the softening and downshift is due to the intensity competition between four components. The BWF component at 1558 cm-1 couples with the electronic continuum and survives until the saturated doping stage.

Ye, J. T.; Li, Z. M.; Tang, Z. K.; Saito, R.

2003-03-01

411

Improved field emission stability from single-walled carbon nanotubes chemically attached to silicon  

PubMed Central

Here, we demonstrate the simple fabrication of a single-walled carbon nanotube (SWCNT) field emission electrode which shows excellent field emission characteristics and remarkable field emission stability without requiring posttreatment. Chemically functionalized SWCNTs were chemically attached to a silicon substrate. The chemical attachment led to vertical alignment of SWCNTs on the surface. Field emission sweeps and Fowler-Nordheim plots showed that the Si-SWCNT electrodes field emit with a low turn-on electric field of 1.5 V??m?1 and high electric field enhancement factor of 3,965. The Si-SWCNT electrodes were shown to maintain a current density of >740 ?A cm?2 for 15 h with negligible change in applied voltage. The results indicate that adhesion strength between the SWCNTs and substrate is a much greater factor in field emission stability than previously reported. PMID:22853557

2012-01-01

412

Vertically oriented single-wall carbon nanotube/enzyme on silicon as biosensor electrode  

NASA Astrophysics Data System (ADS)

Thin films of vertically aligned individual single-wall carbon nanotubes (SWNTs) were deposited on silicon using a chemical vapor deposition (CVD) process. Oriented SWNT growth was achieved by employing two methods of catalyst precursor self-assembly followed by ethanol CVD. Using the silicon substrate as the working electrode in an electrochemical cell and the enzyme ?-NAD (nicotinamide adenine dinucleotide) synthetase dissolved in a buffered electrolyte solution, the enzyme was attached at the nanotube ends. This was shown using scanning electron microscopy and cyclic voltammetry. Enzyme immobilization on the 1 nm to 2 nm diameter tube ends of the individual SWNTs will allow for dense packing of the enzyme and utilization of the electrode as an enzymatic sensor in a biofuel cell configuration.

Wang, Yubing; Iqbal, Zafar

2005-06-01

413

Atomic configuration of nitrogen-doped single-walled carbon nanotubes.  

PubMed

Having access to the chemical environment at the atomic level of a dopant in a nanostructure is crucial for the understanding of its properties. We have performed atomically resolved electron energy-loss spectroscopy to detect individual nitrogen dopants in single-walled carbon nanotubes and compared with first-principles calculations. We demonstrate that nitrogen doping occurs as single atoms in different bonding configurations: graphitic-like and pyrrolic-like substitutional nitrogen neighboring local lattice distortion such as Stone-Thrower-Wales defects. We also show that the largest fraction of nitrogen amount is found in poly aromatic species that are adsorbed on the surface of the nanotube walls. The stability under the electron beam of these nanotubes has been studied in two different cases of nitrogen incorporation content and configuration. These findings provide key information for the applications of these nanostructures. PMID:25157857

Arenal, Raul; March, Katia; Ewels, Chris P; Rocquefelte, Xavier; Kociak, Mathieu; Loiseau, Annick; Stéphan, Odile

2014-10-01

414

Directly synthesized strong, highly conducting, transparent single-walled carbon nanotube films.  

PubMed

We report the direct synthesis of strong, highly conducting, and transparent single-walled carbon nanotube (SWNT) films. Systematically, tests reveal that the directly synthesized films have superior electrical and mechanical properties compared with the films made from a solution-based filtration process: the electrical conductivity is over 2000 S/cm and the strength can reach 360 MPa. These values are both enhanced by more than 1 order. We attribute these intriguing properties to the good and long interbundle connections. Moreover, by the help of an extrapolated Weibull theory, we verify the feasibility of reducing the interbundle slip by utilizing the long-range intertube friction and estimate the ultimate strength of macroscale SWNTs without binding agent. PMID:17629347

Ma, Wenjun; Song, Li; Yang, Rong; Zhang, Taihua; Zhao, Yuanchun; Sun, Lianfeng; Ren, Yan; Liu, Dongfang; Liu, Lifeng; Shen, Jun; Zhang, Zhengxing; Xiang, Yanjuan; Zhou, Weiya; Xie, Sishen

2007-08-01

415

Controlled functionalization of single-walled carbon nanotubes for enhanced ammonia sensing: a comparative study  

NASA Astrophysics Data System (ADS)

Electrochemically controllable functionalization of single-walled carbon nanotubes (SWNTs) with poly(N-methyl pyrrole) (P[NMP]) is demonstrated for room temperature gas sensing applications. Comparative investigations reveal that the loading content of the functionalization entity has prominent effects on the sensing characteristics of SWNTs. The optimized sensing backbone (P[NMP]-functionalized SWNTs with 5 µC deposited charge) exhibited a lower detection limit of 10 ppb and excellent linearity for a detection window of 10 ppb-01 ppm concentration of NH3. The typical response and recovery time of the optimized sensor is on the order of minutes. Finally, a performance comparison of the P[NMP]-functionalized SWNT sensing backbones with the pristine P[NMP] nanowire sensor ensured the well-defined role of SWNTs in the functionalized structure. The proposed sensing mechanism suggests that the synthesis parameters can be manoeuvered for the highest operational efficiency of the sensors.

Datta, K.; Ghosh, P.; More, M. A.; Shirsat, M. D.; Mulchandani, A.

2012-09-01

416

Nonlinear optical and optical limiting properties of individual single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

A large number of individual single-walled carbon nanotubes (SWNTs) were obtained by dilution of nanotube dispersions in N-methyl-2-pyrrolidone (NMP). Up to 70% individual SWNTs are contained in the NMP dispersions with concentrations of less than 4.0×10-3 mg/mL. The nonlinear optical and optical limiting properties of SWNT dispersions were studied by using the Z-scan technique at 532 nm. As the concentration of SWNTs is increased, the nonlinear extinction (NLE) and optical limiting effects improve significantly, while the limiting thresholds decrease gradually. The individual SWNTs show similar NLE effect to zinc phthalocyanine nanoparticles, while also exhibiting larger NLE coefficients than Mo6S4.5I4.5 nanowires.

Wang, J.; Blau, W. J.

2008-06-01

417

Modeling of printed single walled carbon nanotube thin film transistors for attaining optimized clock signals  

NASA Astrophysics Data System (ADS)

As all-printed digital circuits are in high demand to produce all-printed active devices, providing accurate and synchronized clocks to all of the printed circuits is an indispensible step. To supply the clock signal to a printed digital circuit, a printed ring oscillator has been considered as a practical solution. However, it is difficult to fully print the ring oscillators with a consistent and stable clock signal. To resolve this problem, we employed single walled carbon nanotube network (SWNTn) as active layers of printed thin film transistors (TFTs) to completely print the ring oscillator. In addition, using the extracted electronic properties from the printed SWNTn-TFTs, we designed a simulation model based on AIM-Spice Model 15 for the printed ring oscillator and compared the simulated clock signals with the experimentally measured values of the printed ring oscillator.

Noh, Jinsoo; Jung, Minhun; Jung, Kyunghwan; Lim, Soyeon; Lee, Gwangyong; Subramanian, Vivek; Leonard, Ashley D.; Tour, James; Cho, Gyoujin

2010-11-01

418

Solution phase photolysis of 1,2-dithiane alone and with single-walled carbon nanotubes.  

PubMed

Photolysis of 1,2-dithiane (1) in acetonitrile with single walled carbon nanotubes (SWCNTs) was earlier reported to form thiol-functionalized SWCNTs via the butane-1,4-dithiyl diradical (2). The present study shows that 2 instead undergoes a facile rearrangement to thiophane-2-thiol (6). This photoreaction is clean, rapid, and irreversible under 313 nm irradiation. The secondary photolysis of 6 with SWCNTs at a shorter wavelength (254 nm) leads to 2-thiophanyl radicals 8, which derivatize SWCNTs by covalent attachment. Pyrolysis of the resulting "sulfurized SWCNTs" affords a mixture of organosulfur compounds, including thiophene formed by dehydrogenation. An unknown additional mechanism causes high TGA weight loss and a large incorporation of sulfur. PMID:22874092

Engel, Paul S; Gudimetla, Vittal B; Gancheff, Jorge S; Denis, Pablo A

2012-08-16

419

Biointerfacial Property of Plasma-Treated Single-Walled Carbon Nanotube Film Electrodes for Electrochemical Biosensors  

NASA Astrophysics Data System (ADS)

The single-walled carbon nanotube (SWCNT)-based thin film was spray-coated on the Pt support and functionalized using O2 plasma. The effects of plasma treatment on the biointerfacial properties of the SWCNT films were analyzed by cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The plasma-functionalized (pf) SWCNT electrodes modified with Legionella pneumophila-specific probe DNA strands showed a much higher peak current and a smaller peak separation in differential pulse voltammetry and a lower charge transfer resistance, compared to the untreated samples. These results suggest that the pf-SWCNT films have a better electrocatalytic character and an electron transfer capability faster than the untreated SWCNTs, due to the fact that the oxygen-containing functional groups promote direct electron transfer in the biointerfacial region of the electrocatalytic activity of redox-active biomolecules.

Kim, Joon Hyub; Lee, Jun-Yong; Jin, Joon-Hyung; Park, Eun Jin; Min, Nam Ki

2013-01-01

420

Plasma-Etching of Spray-Coated Single-Walled Carbon Nanotube Films for Biointerfaces  

NASA Astrophysics Data System (ADS)

We present an effective method for the batch fabrication of miniaturized single-walled carbon nanotube (SWCNT) film electrodes using oxygen plasma etching. We adopted the approach of spray-coating for good adhesion of the SWCNT film onto a pre-patterned Pt support and used O2 plasma patterning of the coated films to realize efficient biointerfaces between SWCNT surfaces and biomolecules. By these approaches, the SWCNT film can be easily integrated into miniaturized electrode systems. To demonstrate the effectiveness of plasma-etched SWCNT film electrodes as biointerfaces, Legionella antibody was selected as analysis model owing to its considerable importance to electrochemical biosensors and was detected using plasma-etched SWCNT film electrodes and a 3,3',5,5'-tetramethyl-benzidine dihydrochloride/horseradish peroxidase (TMB/HRP) catalytic system. The response currents increased with increasing concentration of Legionella antibody. This result indicates that antibodies were effectively immobilized on plasma-etched and activated SWCNT surfaces.

Kim, Joon Hyub; Lee, Jun-Yong; Min, Nam Ki

2012-08-01

421

Effect of plasma treatment on the gas sensor with single-walled carbon nanotube paste.  

PubMed

The effect of plasma treatment on the gas sensing properties of screen-printed single-walled carbon nanotube (SWCNT) pastes is reported. The gas sensors, using SWCNT pastes as a sensing material, were fabricated by photolithography and screen printing. The SWCNT pastes were deposited between interdigitated electrodes on heater membrane by screen printing. In order to functionalize the pastes, they were plasma treated using several gases which produce defects caused by reactive ion etching. The Ar and O(2) plasma-treated SWCNT pastes exhibited a large response to NO(2) exposure and the fluorinated gas, such as CF(4) and SF(6), plasma-treated SWCNT pastes exhibited a large response to NH(3) exposure. PMID:22284456

Dong, Ki-Young; Ham, Dae-Jin; Kang, Byung Hyun; Lee, Keunsoo; Choi, Jinnil; Lee, Jin-Woo; Choi, Hyang Hee; Ju, Byeong-Kwon

2012-01-30

422

Hybrid solar cells based on single-walled carbon nanotubes/Si heterojunctions  

NASA Astrophysics Data System (ADS)

Photovoltaic devices based on single-walled carbon nanotubes (SWNTs) and n-silicon heterojunctions have been fabricated by a spray deposition process. We provide direct evidence that nanotubes serve as an active photosensing material involved directly in the photon absorption process as well as contributing to charge separation, transport and collection. The characteristic band of the SWNT band in the photoconductivity spectrum matches the S11 absorption band of semiconducting SWNTs of 7,6 chirality. Centrifugation of the SWNTs provides two fractions. The sediment fraction exhibits a conversion efficiency (~1.7%) higher by a factor of eight compared to the supernatant fraction. SEM images and conductivity measurements show that the SWNT network morphology of the sediment fraction has longer and thicker nanotube bundles forming highly porous films, accounting for the enhanced conductivity and higher transparency.

Ong, Pang-Leen; Euler, William B.; Levitsky, Igor A.

2010-03-01

423

Gas sensors based on deposited single-walled carbon nanotube networks for DMMP detection  

NASA Astrophysics Data System (ADS)

Sensors based on single-walled carbon nanotube (SWNT) networks were fabricated and their sensitive properties for the nerve agent stimulant dimethyl methylphosphonate (DMMP) vapor were investigated at room temperature. The SWNT networks were deposited on oxidized silicon surface functionalized with 3-aminopropyltrimethysilane (APS). Combining with a traditional silicon process, SWNT-based gas sensors were made at a wafer scale. The effects of the density of deposited SWNTs on the sensor response were studied. The excellent response is obtained under a density of 30-40 tubes µm-2. The sensors exhibit high resistance response, fast response time, rapid recovery and good reproducibility for DMMP vapor. The deposited SWNT sensors will be potentially extended to large-scale fabrication.

Wang, Yanyan; Zhou, Zhihua; Yang, Zhi; Chen, Xiaohang; Xu, Dong; Zhang, Yafei

2009-08-01

424

Effects of electron exchange-correlation potential on electrostatic oscillations in single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Using macroscopic quantum hydrodynamic formulation, we study the dispersion properties of electrostatic electron plasma oscillations in single-walled carbon nanotubes. The electrons and ions are considered uniformly distributed over the cylindrical surface of a nanotube thus forming a two-component (electron-ion) quantum plasma system. Electron degeneracy via Fermi-Dirac statistics as well as electron exchange and correlation effects is taken into account. It is found that the quantum (Bohm) potential arising due to fermionic nature of electrons and exchange-correlations effects has significant impact on the wave. The frequency of wave is influenced by variation in azimuthal index and radius of the nanotube. The results are analyzed numerically for typical systems for relatively longer wavelength waves and possible consequences are discussed. The results can be important in general understanding of the role of exchange-correlation potential in quantum hydrodynamic treatment of charge-carriers in nanotubes.

Khan, S. A.; Hassan, Sunia

2014-05-01

425

Debundling of single-walled carbon nanotubes by using natural polyelectrolytes  

NASA Astrophysics Data System (ADS)

Natural polyelectrolytes (NPs), including sodium lignosulfonate, humic acid and so forth, are reported for the first time to solubilize single-walled carbon nanotubes (SWNTs) in water through a noncovalent interaction. A variety of methods, including transmission electron microscopy (TEM), visible-near-infrared (vis-NIR) spectra, Raman spectra and zeta potential measurements, were used to characterize the NP-dispersed SWNT solutions. It is found that the SWNTs can be exfoliated into thin bundles or individual tubes, even at NP concentrations as low as 0.15 mg ml-1. Their high performance is attributed to the abundance of aromatic groups and ionized groups in the NP molecules. This method of solubilization opens the way for exploiting new natural materials as SWNT solubilizers and may find applications in nanocomposites, self-assembly, and so forth.

Liu, Yangqiao; Gao, Lian; Zheng, Shan; Wang, Yan; Sun, Jing; Kajiura, Hisashi; Li, Yongming; Noda, Kazuhiro

2007-09-01

426

Self-orientation of short single-walled carbon nanotubes deposited on graphite  

NASA Astrophysics Data System (ADS)

In view of practical handling of single-walled carbon nanotubes (SWNTs), here we present cutting procedures and spontaneous ordering of SWNTs deposited on highly oriented pyrolytic graphite (HOPG). Purified SWNTs were cut by ultrasonication in H2SO4/HNO3 mixture and further in de-ionized water. Thus, prepared short SWNTs were resuspended in methanol and dropped on a freshly cleaved HOPG surface. Scanning tunneling microscopy under a vacuum revealed that the short tubes of 20-100 nm in length were aligned along the basal axis of the HOPG lattice. Tunneling spectroscopy obtained from the oriented tubes indicated a semiconducting behavior, which was characterized in relation to their helical structure. The observed orientation of SWNTs was attributed to their one-dimensional electronic nature along the tube axis with the HOPG lattice.

Yanagi, Hisao; Sawada, Eriko; Manivannan, Ayyakkannu; Nagahara, Larry A.

2001-03-01

427

Charge noise in liquid-gated single-wall carbon nanotube transistors.  

PubMed

The noise properties of single-walled carbon nanotube transistors (SWNT-FETs) are essential for the performance of electronic circuits and sensors. Here, we investigate the mechanism responsible for the low-frequency noise in liquid-gated SWNT-FETs and its scaling with the length of the nanotube channel down to the nanometer scale. We show that the gate dependence of the noise amplitude provides strong evidence for a recently proposed charge-noise model. We find that the power of the charge noise scales as the inverse of the channel length of the SWNT-FET. Our measurements also show that surprisingly the ionic strength of the surrounding electrolyte has a minimal effect on the noise magnitude in SWNT-FETs. PMID:18217786

Männik, Jaan; Heller, Iddo; Janssens, Anne M; Lemay, Serge G; Dekker, Cees

2008-02-01

428

Single-wall carbon nanotubes induce oxidative stress in rat aortic endothelial cells.  

PubMed

Oxidative stress is a major factor contributing to endothelial cell damage. Single-wall carbon nanotubes (SWCNTs) have oxidative properties; however, the oxidative effects of SWCNTs on endothelial cells are not fully understood. In the present study, we investigated the effects of oxidative stress induced by SWCNTs on rat aortic endothelial cells (RAECs). Various markers of cellular damage were assessed, such as biochemical and ES immunity indexes, and DNA and protein damage. Our findings suggest that RAEC endured oxidative damage following SWCNT exposure. Specifically, after SWCNTs exposure, non-enzymatic antioxidant glutathione was activated prior to superoxide dismutase activation in order to defend against oxidative stress. Additionally, it was found that as SWCNT concentration increased, so did the stress protein, heme oxygenase-1 (HO-1), expression levels. These changes may induce RAEC damage, and result in many serious diseases. PMID:22500782

Cheng, Wen-Wen; Lin, Zhi-Qing; Ceng, Qiang; Wei, Bo-Fei; Fan, Xian-Jun; Zhang, Hua-Shan; Zhang, Wei; Yang, Hong-Lian; Liu, Huan-Liang; Yan, Jun; Tian, Lei; Lin, Ben-Cheng; Ding, Shu-Mao; Xi, Zhu-Ge

2012-05-01

429

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

PubMed

The deformation of armchair single-walled carbon nanotube under transverse electric field has been investigated using density functional theory. The results show that the circular cross-sections of the nanotubes are deformed to elliptic ones, in which the tube diameter along the field direction is increased, whereas the diameter perpendicular to the field direction is reduced. The electronic structures of the deformed nanotubes were also studied. The ratio of the major diameter to the minor diameter of the elliptic cross-section was used to estimate the degree of the deformation. It is found that this ratio depends on the field strength and the tube diameter. However, the field direction has little role in the deformation.(See supplementary material 1). PMID:20596520

Kan, Biao; Ding, Jianning; Yuan, Ningyi; Wang, Junxiong; Chen, Zhigang; Chen, Xiaoshuang

2010-01-01

430

Effect of parametric variation on the performance of single wall carbon nanotube based field effect transistor  

NASA Astrophysics Data System (ADS)

The effects of dielectric constant and gate insulator thickness on the performance of single wall carbon nanotube field effect transistors (CNTFETs) have been analyzed using a mathematical model based on FETToy simulator. Both the parameters are found to have significant effect on the device performance, particularly the on-current; while the on-current (ION) increases on scaling down the gate oxide thickness, the level of leakage current (IOFF) is not considerably affected. This is an advantage of CNTFET over conventional MOSFETs where the thickness of thin oxide layer causes drastic increase in gate leakage current. Our analysis results show that thinner gate oxide and larger CNT improve the performance of CNTFETs. Therefore, the performance of our simulated CNTFETs using this model has clear lead over those of conventional MOSFETs.

Kumar, Avshish; Husain, Mubashshir; Khan, Ayub; Husain, Mushahid

2014-11-01

431

Optical detection of DNA conformational polymorphism on single-walled carbon nanotubes.  

PubMed

The transition of DNA secondary structure from an analogous B to Z conformation modulates the dielectric environment of the single-walled carbon nanotube (SWNT) around which it is adsorbed. The SWNT band-gap fluorescence undergoes a red shift when an encapsulating 30-nucleotide oligomer is exposed to counter ions that screen the charged backbone. The transition is thermodynamically identical for DNA on and off the nanotube, except that the propagation length of the former is shorter by five-sixths. The magnitude of the energy shift is described by using an effective medium model and the DNA geometry on the nanotube sidewall. We demonstrate the detection of the B-Z change in whole blood, tissue, and from within living mammalian cells. PMID:16439657

Heller, Daniel A; Jeng, Esther S; Yeung, Tsun-Kwan; Martinez, Brittany M; Moll, Anthonie E; Gastala, Joseph B; Strano, Michael S

2006-01-27

432

Optical Detection of DNA Conformational Polymorphism on Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

The transition of DNA secondary structure from an analogous B to Z conformation modulates the dielectric environment of the single-walled carbon nanotube (SWNT) around which it is adsorbed. The SWNT band-gap fluorescence undergoes a red shift when an encapsulating 30-nucleotide oligomer is exposed to counter ions that screen the charged backbone. The transition is thermodynamically identical for DNA on and off the nanotube, except that the propagation length of the former is shorter by five-sixths. The magnitude of the energy shift is described by using an effective medium model and the DNA geometry on the nanotube sidewall. We demonstrate the detection of the B-Z change in whole blood, tissue, and from within living mammalian cells.

Heller, Daniel A.; Jeng, Esther S.; Yeung, Tsun-Kwan; Martinez, Brittany M.; Moll, Anthonie E.; Gastala, Joseph B.; Strano, Michael S.

2006-01-01

433

Electronic and mechanical modification of single-walled carbon nanotubes by binding to porphyrin oligomers.  

PubMed

We report on the noncovalent binding of conjugated porphyrin oligomers to small diameter single-walled carbon nanotubes (SWNTs) and highlight two remarkable observations. First, the binding of the oligomers to SWNTs is so strong that it induces mechanical strain on the nanotubes in solution. The magnitudes of the strains are comparable to those found in solid-state studies. Comparable strains are not observed in any other SWNT-supramolecular complexes. Second, large decreases in polymer band gap with increasing length of the oligomer lead to the formation of a type-II heterojunction between long chain oligomers and small-diameter nanotubes. This is demonstrated by the observation of enhanced red-shifts for the nanotube interband transitions. These complexes offer considerable promise for photovoltaic devices. PMID:21355592

Stranks, Samuel D; Sprafke, Johannes K; Anderson, Harry L; Nicholas, Robin J

2011-03-22

434

RNA functionalized singled-walled carbon nanotube devices for chemical sensing  

NASA Astrophysics Data System (ADS)

Gas sensing characteristics of single-walled carbon nanotube (SWNT) devices decorated with single-stranded RNA (ss-RNA) were studied. Our results showed that RNA decoration could significantly improve the magnitude of SWNTs' response to methanol and IPA vapors. Furthermore, the sensing characteristics of various RNA functionalized SWNT devices were highly sequence dependent. Specifically, for homo RNA decorated SWNTs, the sensing response followed the trend: C > G > U > A for methanol and G > C > U > A for IPA. For repeated RNA base coated SWNTs, the sensing response trend was: GU > AG > AC > CU for methanol and GU > AC > AG > CU for IPA. These findings provided insight to the binding affinities of RNA oligomers on SWNTs and further paved the way to control the sensing specificity of RNA functionalized SWNT sensors for chemical and biological applications.

Liu, Y.; Chen, M.; Wang, M. L.; Dokmeci, M. R.

2013-09-01

435

Interaction of [FeFe]-hydrogenases with single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

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 II. 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.

Svedruzic Chang, Drazenka; McDonald, Timothy J.; Kim, Yong-Hyun; Blackburn, Jeffrey L.; Heben, Michael J.; King, Paul W.

2007-09-01

436

Interaction of [FeFe]-Hydrogenases with Single-walled Carbon Nanotubes  

SciTech Connect

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.

Chang, D. S.; McDonald, T. J.; Kim, Y.-H.; Blackburn, J. L.; Heben, M. J.; King, P. W.

2007-01-01

437

Fabrication and electrochemical properties of free-standing single-walled carbon nanotube film electrodes  

NASA Astrophysics Data System (ADS)

An easily manipulative approach was presented to fabricate electrodes using free-standing single-walled carbon nanotube (SWCNT) films grown directly by chemical vapor deposition. Electrochemical properties of the electrodes were investigated. In comparison with the post-deposited SWCNT papers, the directly grown SWCNT film electrodes manifested enhanced electrochemical properties and sensitivity of sensors as well as excellent electrocatalytic activities. A transition from macroelectrode to nanoelectrode behaviours was observed with the increase of scan rate. The heat treatment of the SWCNT film electrodes increased the current signals of electrochemical analyser and background current, because the heat-treatment of the SWCNTs in air could create more oxide defects on the walls of the SWCNTs and make the surfaces of SWCNTs more hydrophilic. The excellent electrochemical properties of the directly grown and heat-treated free-standing SWCNT film electrodes show the potentials in biological and electrocatalytic applications.

Niu, Zhi-Qiang; Ma, Wen-Jun; Dong, Hai-Bo; Li, Jin-Zhu; Zhou, Wei-Ya

2011-02-01

438

Effect of medium dielectric constant on the physical properties of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The photophysical properties of semiconducting single walled carbon nanotubes (SWNTs) in different environments are analyzed by steady-state and time-resolved photoluminescence (PL) spectroscopy. The PL emission of SWNTs shows a red shift with the increase of the dielectric constant of the environments. The solvatochromic shift depends on the structural properties of the nanotubes and reaches almost 100 milli-electron volts in the case of (7, 5) tubes. These experimental results allow deriving a relationship between the PL shift and the structure of SWNTs. Moreover, the dynamics of 'bright' excitons in semiconducting SWNTs and the effect of the medium on the decay of the excitons are discussed by using time-resolved spectroscopy.

Gao, J.; Gomulya, W.; Loi, M. A.

2013-02-01

439

Inkjet-printed stretchable single-walled carbon nanotube electrodes with excellent mechanical properties  

NASA Astrophysics Data System (ADS)

Inkjet-printed single-walled carbon nanotube (SWCNT) thin films on stretchable substrates were developed, and their electrical properties were investigated. The 1- and 5-layer printed SWCNT thin films had sheet resistances of 169.76 and 19.08 ?/sq, respectively, and maintained conductive properties under 100% tensile strain. A nitric acid treatment significantly improved the conductivity of the SWCNT electrodes, and after an initial increase, the 5-layer printed SWCNT electrodes showed a normalized resistance of less than 1.2 after 1000 cycles under 100% tensile strain. The potential of the inkjet-printed SWCNT thin films for stretchable electrode applications was demonstrated via integration with a light-emitting diode.

Kim, Taehoon; Song, Hyunsoo; Ha, Jaeheung; Kim, Sangwoo; Kim, Donghyun; Chung, Seungjun; Lee, Jaemyon; Hong, Yongtaek

2014-03-01

440

The structure and electronic properties of copper iodide 1D nanocrystals within single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Copper iodide one-dimensional nanocrystals within single walled carbon nanotubes (1D CuI@SWCNTs), i.e. meta-nanotubes [1], were investigated by high resolution electron microscopy (HRTEM). In meta-nanotubes of diameter Dm = 1.3-1.4 nm produced by arc-discharge (AD) method close-packed hexagonal or deformed cubic 1D crystal anion sublattices were observed with cations in octahedral or tetrahedral positions. These two sublattices reversibly transform to one another. In catalysed chemical vapour deposition (CCVD) meta-nanotubes of diameters Dm = 1.5-2.0 nm cubic anion sublattices are formed. For diameters >=2.0 nm three-dimensional (3D) crystallization is observed.

Kiselev, N. A.; Kumskov, A. S.; Zhigalina, V. G.; Verbitskiy, N. I.; Yashina, L. V.; Chuvilin, A. L.; Vasiliev, A. L.; Eliseev, A. A.

2013-11-01

441

Attachment of Single-wall Carbon Nanotubes (SWNTs) on Platinum Surfaces by Self-Assembling Techniques  

NASA Technical Reports Server (NTRS)

Single-wall carbon nanotubes (SWNTs) are very interesting materials because of their morphology, electronic and mechanical properties. Its morphology (high length-to-diameter ratio) and electronic properties suggest potential application of SWNTs as anode material for lithium ion secondary batteries. The introduction of SWNTs on these types of sources systems will improve their performance, efficiency, and capacity to store energy. A purification method has been applied for the removal of iron and amorphous carbon from the nanotubes. Unpurified and purified SWNTs were characterized by transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). In order to attach carbon nanotubes on platinum electrode surfaces, a self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) was deposited over the electrodes. The amino-terminated SAM obtained was characterized by cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), and Fourier-transforms infrared (FTIR) spectroscopy. Carbon nanotubes were deposited over the amino-terminated SAM by an amide bond formed between SAM amino groups and carboxylic acid groups at the open ends of the carbon nanotubes.This deposition was characterized using Raman spectroscopy and Scanning Electron microscopy (SEM).

Rosario-Castro, Belinda I.; Cabrera, Carlos R.; Perez-Davis, Maria; Lebron, Marisabel; Meador, Michael

2003-01-01

442

Catalytic CVD Synthesis of Single-Walled Carbon Nanotubes from Shigeo Maruyama, Yuhei Miyauchi and Shohei Chiashi  

E-print Network

Catalytic CVD Synthesis of Single-Walled Carbon Nanotubes from Fullerene Shigeo Maruyama, Yuhei CVD technique using fullerene as the carbon source. Powder of C$_{60}$ in a quartz test tube and Fe by conventional catalytic CVD techniques. Most of SWNTs was observed as thin bundles from TEM observations. #12;

Maruyama, Shigeo

443

Large-Scale Production of Single-Walled Carbon Nanotubes Using Ultrafast Pulses from a Free Electron Laser  

Microsoft Academic Search

We report the first use of ultrafast (subpicosecond) laser pulses for large-scale production of single wall carbon nanotubes (SWNT's) by the pulsed laser vaporization (PLV) technique. Very high production rates were achieved; using only 20% of the nominal average power of the 1 kW Jefferson Lab free electron laser (Jlab FEL), carbon soots rich in high quality bundles of SWNT's

P. C. Eklund; B. K. Pradhan; U. J. Kim; Q. Xiong; J. E. Fischer; A. D. Friedman; B. C. Holloway; M. W. Smith

2002-01-01

444

Transfer-matrix simulations of electronic transport in single-wall and multi-wall carbon nanotubes  

E-print Network

transport properties of carbon nano- tubes are another interesting aspect of these structures (see [7 law [1­4] with an emitter work function around 5eV depending on the type of nano- tube. They are alsoTransfer-matrix simulations of electronic transport in single-wall and multi-wall carbon nanotubes

Mayer, Alexandre

445

High-temperature transformation of Fe-decorated single-wall carbon nanohorns to nanooysters: a combined experimental and theoretical study  

NASA Astrophysics Data System (ADS)

The processes by which single-wall carbon nanohorns are transformed by iron nanoparticles at high temperatures to form ``nanooysters'', hollow graphene capsules containing metal particles that resemble pearls in an oyster shell, are examined both experimentally and theoretically. Quantum chemical molecular dynamics (QM/MD) simulations based on the density-functional tight-binding (DFTB) method were performed to investigate their growth mechanism. The simulations suggest that the nanoparticles self-encapsulate to form single-wall nanooysters (SWNOs) by assisting the assembly of dangling carbon bonds, accompanied by migration of the metal particle inside the carbon structure. These calculations indicate that the structure of the oyster consists primarily of hexagons along with a few pentagons that are predominantly formed near the former nanohorn edges as a result of their fusion. Experimental observations of large diameter nanoparticles inside multiwall carbon shells indicate that migration and coalescence of many iron particles must occur, perhaps by the convergence of smaller SWNOs or carbon-coated Fe-nanoparticles, whereby the void space is generated by the corresponding increase in the carbon shell surface area to metal nanoparticle volume.The processes by which single-wall carbon nanohorns are transformed by iron nanoparticles at high temperatures to form ``nanooysters'', hollow graphene capsules containing metal particles that resemble pearls in an oyster shell, are examined both experimentally and theoretically. Quantum chemical molecular dynamics (QM/MD) simulations based on the density-functional tight-binding (DFTB) method were performed to investigate their growth mechanism. The simulations suggest that the nanoparticles self-encapsulate to form single-wall nanooysters (SWNOs) by assisting the assembly of dangling carbon bonds, accompanied by migration of the metal particle inside the carbon structure. These calculations indicate that the structure of the oyster consists primarily of hexagons along with a few pentagons that are predominantly formed near the former nanohorn edges as a result of their fusion. Experimental observations of large diameter nanoparticles inside multiwall carbon shells indicate that migration and coalescence of many iron particles must occur, perhaps by the convergence of smaller SWNOs or carbon-coated Fe-nanoparticles, whereby the void space is generated by the corresponding increase in the carbon shell surface area to metal nanoparticle volume. Electronic supplementary information (ESI) available: Final structures of trajectories A-J at 1500 K and 2500 K. See DOI: 10.1039/c2nr31788e

Chandrakumar, K. R. S.; Readle, Jason D.; Rouleau, Chris; Puretzky, Alex; Geohegan, David B.; More, Karren; Krishnan, Veena; Tian, Mengkun; Duscher, Gerd; Sumpter, Bobby; Irle, Stephan; Morokuma, Keiji

2013-02-01

446

Functional molecules from single wall carbon nanotubes. Photoinduced solubility of short single wall carbon nanotube residues by covalent anchoring of 2,4,6-triarylpyrylium units.  

PubMed

Raw, micrometric HiPCO single wall carbon nanotube (SWNT) material was submitted to harsh acid oxidative treatment with a 3:1 H2SO4/HNO3 mixture to give short residues of SWNT (s-SWNT, <200 nm length measured by TEM). s-SWNT was functionalized through the tip carboxylic groups by peptide bonds using 3-mercatopropanamine linkers that subsequently were reacted with 2,6-diphenyl-4-(4-vinylbiphenyl)pyrylium using azobis(isobutyronitrile) as a radical initiator. After purification by dialysis, the resulting s-SWNT having covalently linked through an ethylthiopropylamide tether the strong electron-transfer pyrylium photosensitizer (Py-sSWNT) was characterized by solution 1H NMR spectroscopy (observation of specific signals due to the heterocyclic protons). Emission spectroscopy shows that the fluorescence of 2,6-diphenyl-4-(4-dodecylthiobiphenyl)pyrylium (Py-SC12) tetrafluoroborate (a model compound to the tethered pyrylium moiety in Py-sSWNT) (lambdaem 533 nm) is quenched by s-SWNT and vice versa that the emission of s-SWNT (lambdaem 330 nm) is quenched by Py-SC12. Depending on the excitation wavelength, Py-sSWNT exhibits dual emission corresponding to each of the two moieties, but with much less intensity than each of the model components independently. Laser flash photolysis of model Py-SC12 allows detection of the triplet (lambdaT-T 750 nm, tau 11.7 micros) and the much longer-lived pyrylium centered radical (lambdamax 525 nm, tau 147 mus). The latter species arises from photoinduced electron transfer from the sulfur atom, as the donor, to the pyrylium heterocycle in its electronic excited-state, as the electron acceptor. Laser flash photolysis (355 nm) of Py-sSWNT also allows detection of the pyrylium centered radical together with a broad absorption spanning from 200 to 500 nm and peaking at 280 nm. The latter band is absent in the laser flash photolysis of the model s-SWNT and was attributed to the electron hole localized on the nanotube moiety of Py-SWNT. The most remarkable effect of the steady-state irradiation is a 1 order of magnitude increase in the solubility of Py-sSWNT. According to TEM images this photoinduced solubility can be attributed to the debundling of the nanotubes due to photoinduced charge separation through the nanotube walls. In addition to exemplify how molecular compounds with photoresponsive properties can be derived from SWNT materials, the observation of photoinduced solubility can serve to develop SWNT layers suitable for photolithography patterning. PMID:17411044

Alvaro, Mercedes; Aprile, Carmela; Ferrer, Belen; Garcia, Hermenegildo

2007-05-01

447

A supramolecular approach for the facile solubilization and separation of covalently functionalized single-walled carbon nanotubes.  

PubMed

Through a combination of an electronic-type selective diazonium-based attachment of a Hamilton receptor unit onto the carbon nanotube framework and a supramolecular recognition approach of a cyanuric acid derivative, we herein introduce a highly promising strategy for the tuning of carbon nanotube solubility and, directly related to that, a solution-based easy and straightforward separation of covalently functionalized carbon nanotube derivatives with respect to their unfunctionalized counterparts. The supramolecular complexation of the cyanuric acid derivative provides the driving force for the dramatically increased dispersibility and for the long-time stability of the individualized single-walled carbon nanotube derivatives in chloroform. The selective covalent functionalization of metallic carbon nanotubes can easily be analyzed with the aid of scanning Raman microscopy techniques. The functional derivatives have furthermore been characterized by UV/Vis-NIR and fluorescence spectroscopy as well as by mass spectrometric coupled thermogravimetric analysis. The investigation of the supramolecular complexation is based on an in-depth UV/Vis-NIR analysis and atomic force microscopy investigations. PMID:24481923

Bosch, Sebastian; Zeininger, Lukas; Hauke, Frank; Hirsch, Andreas

2014-02-24

448

Targeting single-walled carbon nanotubes for the treatment of breast cancer using photothermal therapy  

NASA Astrophysics Data System (ADS)

To develop a therapeutic system with cancer cell selectivity, the present study evaluated a possible specific and localized tumor treatment. Phosphatidylserine (PS) exposure on the external face of the cell membrane is almost completely exclusive to cancer cells and endothelial cells in the tumor vasculature. The human protein annexin V is known to have strong calcium-dependent binding to anionic phospholipids such as PS. This protein was studied for targeting single-walled carbon nanotubes (SWNTs) to the vasculature of breast tumors. The synthesis of the protein annexin V, by a pET vector in Escherichia coli, constitutes the first phase of this study. Recombinant annexin V was purified from the cell lysate supernatant by immobilized metal affinity chromatography. The overall production of purified annexin V protein was 50 mg/L. The binding ability of the protein annexin V was evaluated by determining the dissociation constant when incubated with proliferating human endothelial cells in vitro. The dissociation constant, Kd, was measured to be 0.8 nM, indicating relatively strong binding. This value of Kd is within the range reported in the literature. Single-walled carbon nanotubes (SWNTs) were functionalized with annexin V using two intermediate linkers (containing FMOC and DSPE) resulting in stable suspensions. The SWNT and protein concentrations were 202 mg/L and 515 mg/L, respectively, using the linker with DSPE (average of nine preparations). The conjugation method that used the DSPE-PEG-maleimide linker allowed to successfully conjugate the SWNTs with final concentrations approximately five times higher than the linker containing FMOC. The conjugation method used has a non-covalent nature, and therefore the optical properties of the nanotubes were preserved. The conjugate was also visually observed using atomic force microscopy (AFM), allowing to verify the presence of the protein annexin V on the surface of the nanotubes, with an height ranging between 2.5 to 5.0 nm. Confocal microscopy was used to prove the binding of the conjugates to human endothelial cells grown in vitro. Proliferating endothelial cells were used to determine the optimal near-infrared (NIR) laser irradiation settings (energy density = 200 J/cm2), which would not induce cell cytotoxicity from the laser itself. A 2 hour incubation with the conjugate followed by a washing step and NIR irradiation (wavelength = 980 nm, power = 1 W/cm2, time = 200 seconds) was enough to induce significant cell death (?55 %), without significant damage to the control samples. Administration of the same conjugates i.v. in Balb/cJ female mice resulted in detectable accumulation of the SWNTs in the tumor tissues, with minimal retention in the kidneys 24 hours post-administration. A dosage of 0.82 mg/kg of SWNTs administered i.v. and followed one day later by a NIR irradiation (wavelength = 980 nm, power = 1 W/cm2, time = 175 seconds) led to complete disappearance of implanted 4T1 mouse mammary tumors for the majority of the animals from the treatment groups, within a few days. The combination of the photothermal therapy with a low dosage (50 mg/kg) of the immunoadjuvant cyclophosphamide, given 2 days before NIR irradiation, was also evaluated; this resulted in increased survival. Histological findings revealed the complete obliteration of the tumors treated from the original site, with complete regeneration of the skin epithelial layer and absence of cancer cells. In conclusion, this research was successful in demonstrating that SWNTs could be targeted to the tumor vasculature in vivo and then could be heated by NIR irradiation to completely kill mouse mammary tumors implanted in immune-competent mice. There is evidence that the co-administration of the immunostimulant cyclophosphamide caused increased survival of the mice. It is recommended that future work be directed to exploring methods to increase the concentration of the SWNT-annexin V conjugate in the tumor and to evaluate the co-administration of other immunostimulants, either alone or in combination.

Neves, Luis Filipe Ferreira