Handbook of Nanocomposite Supercapacitor Materials I by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9783030430092
Publisher: Springer International Publishing

6.2 Structure of Carbon Nanotubes

6.2.1 Based on Tube Structure

6.2.1.1 Single-Walled Nanotubes

Single-walled nanotube (SWNT) can be imagined as a perfect graphene sheet consisting of sp2 hybridized carbon in a hexagon, which is rolled in the form of a cylinder with the confirmation that the hexagonal rings located in contact are combined coherently. The tips of the tube are closed by a cap made of hemifullerene of a specific diameter. Single-walled nanotubes (SWNTs) are the nanomaterial of unique properties and behavior and a beautiful material for fundamental physicists and experimental chemists. Geometrically, the SWNT tube diameter can be anything; however, calculations reveal that the SWNT collapses into flatten ribbon-like structure and energetically the ribbon-like structure becomes more favourable once the diameter of the tube reaches 2.5 nm [9]. SWNTs of diameter as low as 0.4 nm have been reported [10]. For the tube length of SWNT, no such restriction is known; however, the length of the tubes will be governed by the method of synthesis and parameters of synthesis such as thermal gradient, residence time. The length of the SWNTs can be a few micrometres to millimetre range. These specific features of SWNT makes them a material of choice due to huge aspect ratio. A simple way of rolling of graphene sheet to form CNT is shown in Fig. 6.2.

Fig. 6.2Rolling up of graphene sheet to form nanotube.

Drawn based on the concept taken from [11]

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