What are Nanotubes?

A carbon nanotube (CNT) is one of the most important nanomaterials. Before 1991, only two main allotropes of carbon were known. In 1991, a Japanese physicist, Sumio Lizima invented CNT (another allotrope of carbon). Let us discuss the carbon nanotubes definition, carbon nanotube is a hollow tube made up of carbon of nanoscale diameter. In short, it is represented as CNTs. Carbon nanotubes are also called buckytube. 

Nanotubes are formed by folding or rolling two-dimensional graphite into a cylindrical shape structure. Nanotubes are hollow from inside. The diameter of the nanotube is around 1-3 nanometers. The length of the carbon nanotube is much higher than its diameter. Nano tube length generally goes to a few micrometers. In short, we can say that carbon nan (CNT) is a folded form of the two-dimensional graphene sheet. CNT (carbon nanotubes) exhibit extraordinary mechanical properties. 

Properties of Carbon Nanotube

  1. Carbon nanotubes are stiff. They are as stiff as a diamond (the hardest natural material in nature).

  2. The gravitational weight of the nanotube is very low. 

  3. The density of the carbon nanotubes is one-fourth of that of steel.

  4.  Carbon nanotubes are stronger than steel. They exhibit extraordinary mechanical properties. Carbon nanotubes are ten times stronger than steel.

  5. Carbon nanotubes have a high thermal capacity. Generally, it is twenty times stronger than steel. Therefore, it does not expand on heating like that of steel. Therefore carbon nanotubes uses in making bridges and aircrafts material

  6. In carbon nanotubes, each carbon atom is surrounded by three other carbon atoms through covalent bonds. These carbon-carbon covalent bonds forms lattice in the shape of hexagons.

  7. The crystalline structure of carbon nanotubes exists in the form of regular hexagons.

  8. Carbon nanotubes are elastic.

  9. Carbon nanotubes are good conductors of heat.

  10. Carbon nanotubes have good electrical conductivity.

  11. The young’s modulus is high. The young modulus of carbon nanotubes is around 1 terra pascal which makes carbon nanotubes ten times stronger than steel.

  12. carbon nanotubes are chemically neutral. So, they are chemically stable. Therefore, carbon nanotubes resist corrosion.

Types of Carbon Nanotubes

  1. Single-walled Carbon nanotubes 

  2. Multi-walled Carbon nanotubes 

Single-walled Carbon Nanotubes- it is represented as SWCNT. The Single-walled Carbon nanotubes exist in a 1-d structure. Some examples of Single-walled CNT are armchair and zig-zag Single-walled Carbon nanotubes

Properties of Single-walled Carbon Nanotubes are:

  • The diameter of Single-walled Carbon nanotubes is 2nm.

  • The length of Single-walled Carbon nanotubes is around 2 micrometres.

  • They exist in a one-dimensional structure. Therefore, it is also known as a nanowire. 

  • Electronics can be miniaturized by using a Single-walled Carbon nanotube.

  • Their band gap varies from 0-2 electron volts (eV).

  • They show conductivity like a semiconductor. Therefore, they exhibit both metallic and semiconductivity behaviour.


The image of armchair carbon nanotubes is shown below:

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Image of zig-zag single-walled carbon nanotubes is shown below:

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Multi-walled Carbon Nanotubes- It is represented as MWCNT. It is composed of several nested carbon nanotubes. This type of nanotubes has two diameters, one is known as outer diameter and another one is known as inner diameter. An example of Multi-walled Carbon nanotubes is chiral Multi-walled Carbon nanotubes. 

Properties of Multi-walled Carbon Nanotubes are given below:

  • The outer diameter of Multi-walled Carbon nanotubes is around 2-20 nanometres.

  • The inner diameter of Multi-walled Carbon nanotubes is 1-3 nm.

  • The length of Multi-walled Carbon nanotubes is around 5-6 micrometres.

How Carbon Nanotubes are Different from Carbon Nanofibres?

Carbon nanofibres are represented as CNFs. Carbon nanofibres have a diameter of around 200 nm. Carbon nanofibres are not hollow from the inside. The lattice structure of the carbon nanotubes and carbon nanofibres are completely different. In Multi-walled Carbon nanotubes, the nano ranged tubes are arranged concentrically but they are hollow from inside. Therefore, Multi-walled Carbon nanotubes are different from carbon nanofibres. Carbon nanofibers have been in use for several decades to strengthen the compounds.

The image of Multi-walled Carbon nanotubes is given below:

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What are Carbon Nanotubes Used For?

Let’s discuss the carbon nanotubes uses one by one:

  • Composite materials containing carbon nanotubes are being used in sporting goods.

  • carbon nanotubes are used to make bullets proof jackets.

  • Carbon nanotubes can be used to make aircraft and space crafts body.

  • carbon nanotubes can be used to build high-performance nanoscaled thin-film transistors to replace silicon-based transistors because of the semiconducting properties of carbon nanotubes.

  • Carbon nanotubes can be used to make biosensors and electrochemical sensors.

  • Carbon nanotubes are used in making electrodes to study electrochemical reactions because of their excellent electrical properties.

Did You Know?

  • Carbon nanotubes are the strongest material known.

  • Carbon nanotubes are generally considered as weightless material.

  • The flexibility of carbon nanotubes material is very high.

FAQs (Frequently Asked Questions)

Question: What are the uses of Carbon Nanotubes?

Answer: The uses of carbon nanotubes are given below:

  • The material made by the combination of the carbon nanotubes is being used in making sports material.

  • The bullets proof jackets can be made by using carbon nanotubes.

  • Carbon nanotubes are very lightweight material. Therefore, it can be used to making aircraft and space crafts body.

  • carbon nanotubes are used in making high-performance nanoscaled thin-film transistors. It replaces silicon-based transistors because of the semiconducting properties of carbon nanotubes.

  • Biosensors and electrochemical sensors are made from carbon nanotubes.

  • Carbon nanotubes are used in making different electrodes (cathode and anode) to study electrochemical reactions because of their excellent electrical properties.

Question: What are the Properties of Carbon Nanotubes?

Answer: The properties of carbon nanotubes are given below:

  • Carbon nanotubes are very tensile. These materials are as stiff as a diamond.

  • The weight of the nanotube is very low. 

  • The carbon nanotubes are less dense than steel. The density of the Carbon nanotubes is ¼ times the steel.

  •  The materials made from carbon nanotubes are stronger than steel. They possess extraordinary mechanical properties. Carbon nanotubes are 10 times stronger than steel.

  • The material made from carbon nanotubes has a high thermal capacity. Generally, these materials are twenty times stronger than steel. So, it does not expand on heating like that of steel. Therefore carbon nanotubes materials are used in making bridges and aircraft.

  • In carbon nanotubes, each carbon atom is surrounded by three other carbon atoms through covalent bonds. These carbon-carbon covalent bonds forms lattice in the shape of hexagons.

  • The crystalline structure of carbon nanotubes exists in the form of regular hexagons.

  • Carbon nanotubes are elastic.

  • Carbon nanotubes are good conductors of heat.

  • Carbon nanotubes have good electrical conductivity.

  • The young’s modulus is high. The young modulus of carbon nanotubes is around 1 terra pascal which makes carbon nanotubes ten times stronger than steel.

  • carbon nanotubes are chemically neutral. So, they are chemically stable. Therefore, carbon nanotubes resist corrosion.