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This study demonstrates the first example of the use of a metal-free catalyst for the continuous synthesis of carbon nanotubes (CNTs) by chemical vapor deposition (CVD). In this paper silica nanoparticles produced from the thermal decomposition of PSS-(2-(trans-3,4-Cyclohexanediol)ethyl)-Heptaisobutyl substituted (POSS) were used as catalyst and ethanol was served as both the solvent and the carbon source for nanotube growth. The POSS/ethanol solution was nebulized by an ultrasonic beam. The tiny mists were continuously introduced into the CVD reactor for the growth of CNTs. The morphology and structure of the CNTs have been investigated by scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. The obtained CNTs have a multi-walled structure with diameters mainly in the size range from 13 to 16 nm. Detailed investigations on the growth conditions indicate that the growth temperature and POSS concentration are important for achieving high-quality nanotubes, and that the existing of small amount of water in ethanol is effective to remove amorphous carbon species during the formation of CNTs. The mass production of CNTs without any metal contaminant will provide a chance for investing and understanding the intrinsic properties of CNTs and applications particularly in nanoelectronics and biomedicines. 相似文献
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Siang-Piao Chai 《Materials Letters》2007,61(16):3519-3521
A simple nickel oxide catalyst has been developed in synthesizing single-walled carbon nanotubes (SWNTs) at moderate temperature. The catalyst used in the experiment was without a preceding reduction in hydrogen flow. The synthesis of SWNTs was performed at a temperature of 700 °C, which represents a moderate reaction temperature. The presence of SWNTs on the catalyst was confirmed by transmission electron microscope (TEM) and Raman spectroscope. The Raman spectrum shows a strong intensity at the radial breathing mode, indicating that the occurrence of SWNTs was dominant. Raman data further reveals that the synthesized SWNTs had the diameters in the range from 0.58 to 2.02 nm. 相似文献
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Fatima Z. BouanisLaurent Baraton Vincent HucDidier Pribat Costel S. Cojocaru 《Thin solid films》2011,519(14):4594-4597
We investigated the single-walled carbon nanotubes (SWCNTs) growth on Ru nanoparticle catalyst via hot filament assisted chemical vapor deposition (HFCVD) with two independent W filaments for the carbon precursor (methane) and the hydrogen dissociation respectively. The Ru nanoparticles were obtained following a two-step strategy. At first the growth substrate is functionalized by silanisation, then a self assembly of a ruthenium porphyrin complex monolayer on pyridine-functionalized metal oxide substrates. We have studied the impact of the filaments power and we optimized the SWCNTs growth temperature. The as grown SWCNTs were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. It was found that the quality, density and the diameter of SWCNTs depends on the filament and growth temperature. Results of this study can be used to improve the understanding of the growth of SWCNTs by HFCVD. 相似文献
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L. C. QIN 《Journal of Materials Science Letters》1997,16(6):457-459
Abstracts are not published in this journal
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
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B. Rajesh K. Ravindranathan Thampi J. -M. Bonard B. Viswanathan 《Bulletin of Materials Science》2000,23(5):341-344
The template carbonization of polyphenyl acetylene yields hollow, uniform cylindrical carbon nanotubes with outer diameter
almost equal to pore diameter of the template used. High resolution transmission electron microscopic investigation reveals
that Pt-Ru nanoparticles are highly dispersed inside the tube with an average particle size of 1.7 nm. 相似文献
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Catalyst and reaction conditions are the main affecting factors for the yield and quality of carbon nanotubes (CNTs) produced by the chemical vapor deposition (CVD) method. In this paper a ternary component catalyst based on Fe-Ni-Mo/MgO was explored using methane as precursor. The influences of temperature and methane concentration were investigated, and the as-produced CNTs were characterized by SEM, HRTEM, XRD and TGA. The diameter of the CNTs is in the range of 20-30 nm and the maximum carbon yield can reach up to 80 times of the catalyst under the selected condition. The purity of the as-prepared CNTs is over 93%. Our results indicated that this novel tercomponent catalyst presented a good catalytic activity for manufacturing high quality and quantity of CNTs. 相似文献
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Muramatsu H Hayashi T Kim YA Endo M Terrones M Dresselhaus MS 《Journal of nanoscience and nanotechnology》2005,5(3):404-408
Here we describe the effect of different synthetic conditions on the quality and purity of double-walled carbon nanotubes (DWNTs) with the aid of a conditioning catalyst. By lowering the reaction temperature down to 875 degrees C and utilizing a conditioning catalyst, increased purity and a decreased inner diameter of the DWNTs was achieved, while adverse results were observed with increasing reaction temperature. Based on detailed high-resolution transmission electron microscopy studies on the diameter distribution of the tubes, preferential growth conditions for DWNTs over single-wall carbon nanotubes are identified solely from increased carbon solubility considerations (caused by an increased portion of active carbon species by use of Mo) for the same distribution of metal particles. 相似文献
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Boron nitride nanotubes (BN-NTs) were synthesized in large scale by the reaction of NaBH4 and NH4Cl in the temperature range of 500-600 °C for 10-18 h, where carbon nanotubes (CNTs) were mixed together with the reactants to serve as template. Pure BN-NTs were obtained by oxidizing the product at about 800 °C in air atmosphere. The structure and morphology of the product with a surface area of 106.635 m2/g were characterized by X-ray diffraction, transmission electron microscopy, Fourier transformation infrared spectroscopy, and thermogravimetric analysis. Large scale preparation of BN-NTs could be realized by this simple and effective route. 相似文献
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Balbuena PB Zhao J Huang S Wang Y Sakulchaicharoen N Resasco DE 《Journal of nanoscience and nanotechnology》2006,6(5):1247-1258
Classical molecular dynamics simulations are carried out to analyze the physical state of the catalyst, and the growth of single-wall carbon nanotubes under typical temperature and pressure conditions of their experimental synthesis, emphasizing the role of the catalyst/substrate interactions. It is found that a strong cluster/substrate interaction increases the cluster melting point, modifying the initial stages of carbon dissolution and precipitation on the cluster surface. Experiments performed on model Co-Mo catalysts clearly illustrate the existence of an initial period where the catalyst is formed and no nanotube growth is observed. To quantify the nature of the Co-Mo2C interaction, quantum density functional theory is applied to characterize structural and energetic features of small Co clusters deposited on a (001) Mo2C surface, revealing a strong attachment of Co-clusters to the Mo2C surface, which may increase the melting point of the cluster and prevent cluster sintering. 相似文献
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Very shortly following the discovery of single-walled carbon nanotubes laser-based methods emerged as reliable ways to produce moderate quantities with very consistent composition and properties. They have also proven to be good platforms for the systematic investigation of various synthesis parameters in the hope of better understanding the growth process. Several variations exist with differences such as laser wavelength, number of lasers, background temperature, and target composition. A number of common elements have emerged for the production of both high quality and high yields of SWNT, such as the effectiveness of bimetal catalysts like CoNi and NiY, and the need for high process temperatures and controlling the rate of cooling. Combined with the growing amount of in situ diagnostic and computational modelling data we are slowly making progress towards understanding the growth process. This article will present an overview of recent advancements in laser-based synthesis methods and what information can be extracted about the growth process. 相似文献
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We report a novel approach to grow highly oriented, freestanding and structured carbon nanotubes (CNTs) between two substrates, using microwave plasma chemical vapour deposition. Sandwiched, multi-layered catalyst structures are employed to generate such structures. The as-grown CNTs adhere well to both the substrate and the top contact, and provide a low-resistance electric contact between the two. High-resolution scanning electron microscope (SEM) images show that the CNTs grow perpendicular to these surfaces. This presents a simple way to grow CNTs in different, predetermined directions in a single growth step. The overall resistance of a CNT bundle and two CNT-terminal contacts is measured to be about 14.7?k Ω. The corresponding conductance is close to the quantum limit conductance G(0). This illustrates that our new approach is promising for the direct assembly of CNT-based interconnects in integrated circuits (ICs) or other micro-electronic devices. 相似文献
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Multi-walled carbon nanotubes (MWCNTs) with large inner diameter were synthesized by the catalytic chemical vapor deposition method using HBO3 as the accessorial catalyst in reaction precursors. A ratio Din/Dout is defined as an index to evaluate the hollow degree of MWCNTs, where Din and Dout are the inner and outer diameter of one CNT, respectively. When no HBO3 was added in the reaction mixtures, the MWCNTs are straight with thick wall. The average Din/Dout value is only 0.08 ± 0.02. The X-ray diffraction (XRD) result shows the relatively low crystallinity. When HBO3 was added in the reaction precursors, the MWCNTs have large inner cavity and the average Din/Dout value reaches 0.57 ± 0.10. The crystallinity was also improved remarkably. These results indicate that HBO3 in the catalyst system has great influence on the growth of MWCNTs. 相似文献