CNT is the abbreviation of carbon nanotube that was accidentally discovered by Japanese scientist Iijima in 1991. Since then, with the unique mechanical strength, amazing electrical properties and potential applications in chemicals and materials, CNT has attracted the attention of scientists all over the world. CNT, also known as buckytube, belongs to the fullerenes carbon system, and it is seamless nanotube made of single or multi-layer curled graphite sheets. The diameter of CNT is generally between 1 nm and 30 nm, while the length can reach micron level and the aspect ratio is between 100 and 1000. Therefore, CNT can be regarded as a one-dimensional quantum line.
- Catalyst filed: Because of the quantum effect, CNT has the properties of specific catalysis and photocatalysis, which makes people have great interest in the application in catalytic chemistry. With the advantages of unique cavity structures and excellent adsorption properties, CNT are mainly used as catalyst carriers in catalysis, showing great application potential in hydrogenation, dehydrogenation and shape-selecting catalytic reactions. Moreover, once CNT are used in catalytic chemistry, the activity and selectivity of the reaction can be greatly improved, which is expected to produce great economic benefits.
Figure 1. An example of CNT applied in catalyst filed.
- Lithium-ion batteries field: As a significant green energy, lithium ion batteries are developing towards high energy density. Therefore, it is necessary to find a suitable electrode material to ensure the batteries have high voltage, large capacity and long cycle life. The special structure of CNT makes it a good cathode material for lithium ion batteries. The large layer spacing makes it easier for lithium ions to be intercalated and deintercalated, and the tubular structure will not collapse after multiple charge and discharge cycles, which can greatly improve the performance and life of lithium ion batteries.
Figure 2. An example of CNT applied in Lithium-ion battery.
- Supercapacitors field: Supercapacitors have extremely important and broad applications in mobile communications, information technology, electric vehicles, aerospace and many other aspects. Finding electrode materials that allow supercapacitors to have both high energy and power density is the key to improving the performances of supercapacitors. With the excellent chemical and physical properties, CNT is an ideal candidate electrode material for supercapacitors.
- The others: CNT is also widely used in many other fields, including adsorptive materials, wave-absorbing materials, hydrogen storage materials and the others. Due to the excellent adsorption capacity, CNT can be used as adsorbent to remove trace amounts of heavy metals or organic compounds in water. In addition, CNT is the most promising new wave-absorbing materials due to their excellent wave absorbing properties, light weight, good compatibility and wide frequency band. Furthermore, with the unique nanoscale size, hollow structure and larger specific surface area, CNT are ideal hydrogen storage materials.
According to the number of carbon atoms layers, CNT can be roughly divided into single-walled carbon nanotubes and multi-walled carbon nanotubes.
- Single-walled carbon nanotubes: Single-walled carbon nanotubes are formed by wrapping a single layer of carbon atoms, and the structure has good symmetry and singleness.
- Multi-wall carbon nanotubes: Multi-wall carbon nanotubes are composed of many columnar carbon tubes with the same axle sheath and the number of carbon atoms layers is between 2 and 50.
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