Papers by Keyword: Single-Walled Carbon Nanotube (SWCNT)

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Authors: L. Li, S. Reich, J. Robertson
Abstract: We investigated the nucleation of SWNTs and the role of metallic catalyst using firstprinciples calculations. To avoid dangling bonds a closed cap forms on a metal surface. 6 pentagonal rings are introduced into the cap, which reduces the strain energy. A unique tube chirality then grows from the cap, which is controlled by the metal lattice at the nucleation stage. We found that chirality of nanotubes affects the bond energies, including dangling bonds, carbon-carbon bonds & carbonmetal bonds.
Authors: Xian Gui Ni, Z. Zhang, Y. Wang, Xiu Xi Wang
Abstract: Three armchair single-walled carbon nanotubes (SWCNTs) (7, 7), (12, 12), (17, 17) and three zigzag SWCNTs (12, 0), (16, 0), (20, 0) are investigated in this paper, using the molecular dynamic (MD) method with the second-generation Tersoff-Brenner (TB) potential. The Poisson’s ratio of these nanotubes under tensile and compressive loading is obtained. The effect of the strain and size on the Poisson’s ratio of nanotubes is analyzed systematically, from the viewpoints of the structure and the averaged atomic potential energy of nanotubes. The results show that the Poisson’s ratio of nanotubes decreases as the strain increases. The Poisson’s ratios of nanotubes of larger chiral angle decrease more quickly. For nanotubes of the same chiral angle, the larger the diameters of nanotubes are, the larger their Poisson’s ratios become. Moreover, the Poisson’s ratios of nanotubes of larger diameter are more approaching.
Authors: Qiang Zeng, Y. Bayazitoglu, Jiang Zhu, Kenneth Wilson, M. Ashraf Imam, Enrique V. Barrera
Abstract: This study considers a method for producing SWNTs reinforced lightweight metal-matrix composites. In this research, fluorination has been applied to achieve considerable improvement in the dispersion of purified single-walled carbon nanotubes. It has been demonstrated that surface fluorination is a possible approach to entrap catalytic nucleation centers along the walls of SWNTs. The results show that nickel could be successfully plated onto the activated surfaces of fluorinated SWNTs (F-SWNTs) through electroless plating which is an effective way for producing nanotube/metal systems. It was observed that high surface coverage of Pd-Sn catalytic nuclei is needed to form high quality coatings. A two-step approach was used and the coating mechanism is described in this paper.
Authors: Zhao Gang Nie, Xin Zhong Li, Takayoshi Kobayashi
Abstract: We studied coherent phonon dynamics in Co-Mo-catalyst grown single-walled carbon nanotubes by using sub-5-fs visible pulses. Vibrational wave-packets corresponding to radial breathing mode for four chiral systems, (6,4), (6,5), (7,5) and (8,3), can be separately observed and achieved exact chirality assignments without ambiguity in coherent phonon spectra. Coherent phonon generation of radial breathing modes is in-depth studied by analyzing the probe energy dependent amplitude profiles, which indicates that the real and imaginary parts of the third-order susceptibility can both contribute to the modulation of the probed difference absorbance.
Authors: Jie Meng, Li Song, Jun Zhong, Chao Ying Wang, Hua Kong, Zi Yu Wu, Hai Yan Xu, Si Shen Xie
Abstract: Fibrinogen and albumin are two of the most important plasma proteins that relate to blood coagulation caused by engineered surfaces. In this paper, the adsorption behavior of albumin and fibrinogen on single-walled carbon nanotubes nonwoven (SWNT nonwoven) was investigated through scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), near edge X-ray adsorption fine structure spectroscopy (NEXAFS) and direct enzyme-linked immunosorbent assay (ELISA) respectively. It was concluded that SWNT nonwoven displayed strong adsorption preference of fibrinogen to albumin. In addition, the immune activity of fibrinogen adhered to the SWNT nonwoven surface was found remained and showed a linear response to the concentration in a certain range.
Authors: Ke Rong He, Zhi Chu Lu
Abstract: In this paper, methane adsorption in single-walled carbon nanotube (SWNT) has been simulated by using the grand canonical ensemble Monte Carlo (GCMC) method. Lennard-Jones (LJ) potential is used to represent the fluid-fluid interaction, and integral method is used to calculation of the potential between fluid molecules and carbon atoms. In the simulation, adsorption isotherms of methane in the (15, 15), (20, 20), (25, 25) and (30, 30) SWNT are simulated.
Authors: Hong Mei Niu
Abstract: Nanocomposites of single-walled carbon nanotubes modified polypyrrole (PPy/SWNTs) were synthesized successfully by in situ oxidative polymerization method in the FeCl3·6H2O solution. The morphological structure, electrical conductivity and thermal stability of the nanocomposites were characterized by TEM, SEM, FTIR and TGA. The PPy/SWNTs were 50-100 nm in diameter of PPy coating uniformly on the surface of the SWNTs. FTIR spectra revealed the presence of covalently interaction between the PPy and the carbon nanotubes. The electrical conductivity of PPy/SWNTs composite and pure PPy were 93 and 8.0×10-3 S/cm, respectively. Meanwhile, the PPy/SWNTs composites possessed higher thermal stability (65.9 wt. % weight loss at 600 °C) compared to pure PPy (81.2 wt. % weight loss at 600 °C), the content of SWNTs was 15.3 wt. %.
Authors: Reza Yadipour, Karim Abbasian, Bita Azemoodeh Afshar, Ali Rostami
Abstract: In this paper, a solid-state dye sensitized solar cell (DSSC) based on carbon nanotubes by inserting N719 dye molecules has been designed for operating at 300oK and 330oK temperatures. The role of carbon nanotubes as hole and electron conducting agents and dye molecules as absorber of solar radiation and hole-electron pair producing agents has been discussed. After inserting N719 dye, parameters of the cell such as absorption coefficient of both layers (ZNO+SWNT, P3HT+SWNT), current density of solar cell , internal and external quantum efficiency of P3HT+SWNT layer have been obtained at 300oK and 330oK, numerically. Then, improvement value of energy conversion efficiency of the cell has been compared after inserting carbon nanotubes.
Authors: Yong Jae Kim, Sang Hwan Lee, Do Young Byun, Sang Joon Han, Ji Hye Yang, Han Seo Ko, Seung Hyun Baik
Abstract: We propose to use electrostatic drop-on-demand devices, with precise metering and accurate delivery capabilities, to manipulate single-walled carbon nanotubes suspended in solution. The conductivity of the solution increases significantly by the addition of anionic surfactants and nanotubes, generating favorable conditions for electrostatic ejection. This technique could find applications, combined with chemical functionalization, in the fabrication of carbon nanotube field emission devices as well as electronic circuits.
Authors: Shiuh Chuan Her, Shou Jan Liu
Abstract: A micromechanical finite element model incorporated with molecular mechanics is employed to determine the mechanical properties of single-walled carbon nanotubes (SWCNT). The SWCNT is modelled as a space-frame structure. The bonds between the carbon atoms are simulated as beam members to carry the loads, while the carbon atoms are the joints of the members. The modified Morse potential is adopted to characterize the non-linear behavior of C-C bonds. In this work, the mechanical properties of SWCNT such as the Young’s modulus, ultimate strength and strain are investigated. To verify the proposed FE model and evaluate its performance, the effects of diameter and chirality on the mechanical properties of SWCNT are presented. It is found that both the Young’s modulus and ultimate strength of SWCNT increase monotonically with the increase of diameter. The Young’s modulus of armchair is larger than that of zigzag SWCNTs. These results are in good agreement with the existing numerical and experimental results.
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