Carbon nanotubes opening

P. M. Ajayan, T. W. Ebbesen, Ichihashi, S. Ijima, K. Tanigaki, H. Hiura, Opening carbon nanotubes with oxygen and implications for filling, Nature, vol. 362, pp. 522-525,1993. 

Fig. 1.1 Idealized representation of different structures of defect-free and opened carbon nanotubes (a) concentric MWCNT (b) metallic armchair [10,10] SWCNT (c) helical...

Abstract. Equilibrium configurations, total energy, heat of formation, energies of HOMO and LUMO orbitals, density of one-electron states (DOS) of open and semi open carbon nanotubes of variable diameter such types as (6,6)+(6,0), (5,5)+(5,0) and (6,0)+(5,0) are determined in frames of semi-empirical quantum chemistry PM3-method. 

Pan ZW, Xie SS, Chang BH et al. (1999) Direct growth of aligned open carbon nanotubes by chemical vapour deposition. Chem Phys Lett 299 97-102... 

Darkrim, F. and Levesque, D. (2000). High adsorptive property of opened carbon nanotubes at 17K.J. Phys. Chem. B, 104, 6773—6. 

A principal distinction can be made between single-walled nanotubes (SWNT) and multiwalled nanotubes (MWNT). Both classes comprise species of most different diameters and lengths. Besides dimensions, it is also the way the graphene layer is rolled up to be a tube that dominantly influences the properties of the resulting materials. Furthermore, there may or may not be caps at the tubes ends, the respective structures then are called closed or open carbon nanotubes. The structural features of single-walled nanotubes will be discussed first in the following before the concept shall be extended to the multiwalled variants then. 

Examples of capping units that covalently bond to open carbon nanotubes to yield closed tubes. The examples shown are portions of a C o molecule and are compatible with (a) an armchair and (b) a zigzag carbon nanotube. 

Ajayan PM, Ebbesen TW, Ichihashi T, lijima S, Tanigaki K, Hiura H. Opening carbon nanotubes with oxygen and implications for filhng. Nature 1993 362 522-5. 

Hiraoka, T. et al. 2010. Compact and light supercapacitor electrodes from a surface-only solid by opened carbon nanotubes with 2200 m. g surface area. Advanced Functional Materials, 20, 422-428. 

Carbon nanotubes have been studied extensively in relation to fullerenes, and together with fullerenes have opened a new science and technology field on nano scale materials. This book aims to cover recent research and development in this area, and so provide a eonvenient reference tool for all researchers in this field. It is also hoped that this book can serve to stimulate future work on carbon nanotubes. 

Hollow carbon nanotubes (CNTs) can be used to generate nearly onedimensional nanostrutures by filling the inner cavity with selected materials. Capillarity forces can be used to introduce liquids into the nanometric systems. Here, we describe experimental studies of capillarity filling in CNTs using metal salts and oxides. The filling process involves, first a CNT-opening steps by oxidation secondly the tubes are immersed into different molten substance. The capillarity-introduced materials are subsequently transformed into metals or oxides by a thermal treatment. In particular, we have observed a size dependence of capillarity forces in CNTs. The described experiments show the present capacities and potentialities of filled CNTs for fabrication of novel nanostructured materials. 

Purification, Opening, and Size Reduction of Carbon Nanotubes by Oxidative Treatments... 

Another interesting type of novel carbons applicable for supercapacitors, consists of a carbon/carbon composite using nanotubes as a perfect backbone for carbonized polyacrylonitrile. Multiwalled carbon nanotubes (MWNTs), due to their entanglement form an interconnected network of open mesopores, which makes them optimal for assuring good mechanical properties of the electrodes while allowing an easy diffusion of ions. 

An important route to solubilization of carbon nanotubes is to functionalize their surface to form groups that are more soluble in the desired solvent environment. It has been shown that acid treatment of nanotube bundles, particularly with HC1 or HNO3 at elevated temperatures, opens up the aggregate structure, reduces nanotube length, and facilitates dispersion (An et al., 2004 Kordas et al., 2006). Nitric acid treatment oxidizes the nanotubes at the defect sites of the outer graphene sheet, especially at the open ends (Hirsch, 2002 Alvaro et al., 2004), and creates carbonyl, carboxyl, and hydroxyl groups, which aid in their solubility in polar solvents. 

S.C. Tsang, P.J.F. Harris, and M.L.H. Green, Thinning and opening of carbon nanotubes by oxidation using carbon dioxide. Nature 362, 520-522 (1993). 

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