Carbon nanotube preparation methods

ACTIVE CARBON AND CARBON NANOTUBE PREPARATION METHODS... 

Metal Filling in Carbon Nanotubes Prepared by Arc-Discharge Method... 

The most widely used method of fullerene and carbon nanotube preparation is an arc discharge in a buffer gas. Helium is usually applied as the gas. Argon is more widespread and cheap gas than helium. However the fullerene yield is less than 2 % with that gas whereas in a helium arc discharge it is about ten times greater. We have worked out an effective method of small quantity fullerene preparation by means of an argon arc discharge [1-3]. This report informs about the further investigation in this direction. 

Ci LJ, Zhou ZP, Yan XQ, Liu DF et al (2003) Resonant Raman scattering of double wall carbon nanotubes prepared by chemical vapor deposition method. J Appl Phys 94(9) 5715-5719... 

Carbon nanotubes prepared by several methods are mixed with nanoparticles, amorphous carbon, fullerenes, and other contaminants [1576]. Nanotubes isolated from the mixture contain single-walled (SWNT) as well as multiwalled (MWNT) nanotubes. In general, the diameter of a SWNT is on the order of several nanometers, but the length can be several microns. Thus far, spectroscopic (mainly Raman) studies have been focused on SWNTs of small diameters (<2nm) that become metallic or semiconducting depending on their diameter and chirality. Chemical and physical... 

Ci L, Wei J, Wei B, Liang J, Xu C, Wu D. Carbon nanofibers and single-waUed carbon nanotubes prepared by the floating catalyst method. Carhon 2001 39 329-35. 

Ci, L. et al. (2001). Carbon Nanofibers and Single-walled Carbon Nanotubes Prepared by the Floating Catalyst Method. Carbon, 39, 329-335. 

T. Kyotani, L. Tsai, A. Tomita, 1997. Formation of nanorods and nanoparticles in uniform carbon nanotubes prepared by a template carbonization method. Chemical Communications, 7 701-702. 

The FR rate spectroscopy proved to be an effective method to characterize the sorption dynamics of alkanes in various carbon nanotube preparations. 

Cui, Z., Liu, C., Liao, J., and Xing, W. (2008) Highly active PtRu catalysts supported on carbon nanotubes prepared by modified impregnation method for methanol electro-oxidation. Electrochimica Acta, 53 (27),... 

Carbon nanotubes, prepared from coal by an arc discharge method, were investigated as the matrix for analyses of small molecules by MALDl-MS. It was observed that the carbon nanotube layer on the probe before deposition of sample solution appears to have web morphology, which was masked by formation of analyte microcrystals after deposition of the sample solution. However, there is almost no change in configuration and shape for a single piece of carbon nanotube before and after the deposition of sample solution on the carbon nanotube layer (Figure 7.7). Nanotubes provide a lower laser power threshold for... 

Fig. 1. Comparalive preparation methods for micrometer size fibrous carbon and carbon nanotubes as one-dimensional forms of carbon.

In the theoretical carbon nanotube literature, the focus is on single-wall tubules, cylindrical in shape with caps at each end, such that the two caps can be joined together to form a fullerene. The cylindrical portions of the tubules consist of a single graphene sheet that is shaped to form the cylinder. With the recent discovery of methods to prepare single-w alled nanotubes[4,5), it is now possible to test the predictions of the theoretical calculations. 

Carbon nanotubes were first thought of as perfeet seamless eylindrieal graphene sheets —a defeet-free strueture. However, with time and as more studies have been undertaken, it is elear that nanotubes are not neeessarily that perfeet this issue is not simple bc-eause of a variety of seemingly eontradictory observations. The issue is further eomplicated by the faet that the quality of a nanotube sample depends very mueh on the type of maehine used to prepare it[l]. Although nanotubes have been available in large quantities sinee 1992[2], it is only recently that a purification method was found[3]. So, it is now possible to undertake various accurate property measurements of nanotubes. However, for those measurements to be meaningful, the presence and role of defeets must be elearly understood. 

Electron irradiation (100 keV) of the sample, heated to 800°C, yields MWCNTs (20-100 nm in length) attached to the surface. Such nanotube growth does not take place if natural graphite, carbon nanoparticles or PTFE are subjected to electron irradiation. The result implies that the material may be a unique precursor for CNTs and may constitute a new preparation method. 

Xin and co-workers modified the alkaline EG synthesis method by heating the metal hydroxides or oxides colloidal particles in EG or EG/water mixture in the presence of carbon supports, for preparing various metal and alloy nanoclusters supported on carbon [20-24]. It was found that the ratio of water to EG in the reaction media was a key factor influencing the average size and size distribution of metal nanoparticles supported on the carbon supports. As shown in Table 2, in the preparation of multiwalled carbon nanotube-supported Pt catalysts... 

Incorporation of nitrogen into the carbons prepared via chemical vapour deposition (CVD) or into the carbon nanotubes yields highly graphitised materials with excellent structure ordering. For example, ordered mesoporous carbons containing 7.0-8.8 wt,% N have been obtained by the CVD method, using the SBA-12, SBA-15, MCM-41, MCM-48, and HMS materials as matrices and acetonitrile as carbon precursor [1],... 

In view of the conductive and electrocatalytic features of carbon nanotubes (CNTs), AChE and choline oxidases (COx) have been covalently coimmobilized on multiwall carbon nanotubes (MWNTs) for the preparation of an organophosphorus pesticide (OP) biosensor [40, 41], Another OP biosensor has also been constructed by adsorption of AChE on MWNTs modified thick film [8], More recently AChE has been covalently linked with MWNTs doped glutaraldehyde cross-linked chitosan composite film [11], in which biopolymer chitosan provides biocompatible nature to the enzyme and MWNTs improve the conductive nature of chitosan. Even though these enzyme immobilization techniques have been reported in the last three decades, no method can be commonly used for all the enzymes by retaining their complete activity. 

Van Steen, E., andPrinsloo, F. F. 2002. Comparison of preparation methods for carbon nanotubes supported iron Fischer-Tropsch catalysts. Catalysis Today 71 327-34. 

Ma, D. Moy, A. Chishti, J. Yang, Method For Preparing Supported Catalysts From Metal Loaded Carbon Nanotubes, 2005, U.S. Patent US20060142149. 

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