Applications of Carbon Nanotubes (CNTs)

APPLICATIONS OF CARBON NANOTUBES

The unusual properties of carbon nano tubes have many applications such as battery electrodes, electronic devices and reinforcing fibers for stronger composites etc.,

Electrical and Electronics applications

i. When a small electrical field is applied parallel to the axis of a nanotube, the electrons are emitted at a very high rate from the ends of the tube. This is called field emission and it is used in development of flat panel displays.

ii. Vacuum tube lamps that are as bright as conventional light bulbs with long life time and more efficient can be produced using CNT.

iii. Semiconducting carbon nanotubes connecting two gold electrodes form field effect transistors (FET) device as shown in fig. 5.19.

The switching time of these devices is very fast. They exhibit clock speeds of a terahertz which is 10⁴ times faster than present processors. Further, small size allows a large number of component in a chip.

ii. Carbon nanotubes with diameters of 2 nm have extremely low resistance and thus they can carry large currents without getting heated. So, they can be used as interconnects in chip.

Computer applications

Carbon nanotubes can be used to make a computer switching device as shown in fig.5.20.

Battery technology

(i) Carbon nanotubes have many applications in battery technology. Lithium which is a charge carrier in some batteries, can be stored inside nanotube.

(ii) Carbon nano tube can be used for storing the hydrogen which is used in the development of fuel cells.

The cell consists of an electrolytic solution of KOH with a negative electrode consisting of carbon nanotube (CNT) paper (fig.5.21).

Mechanical Applications

(i) Nanotubes can be used to increase the tensile strength of steel.

(ii) A plastic composite of carbon nanotubes provides light weight shielding material for electromagnetic radiation.

Chemical applications

i. A field-effect transistor made of chiral semiconducting carbon nanotubes is used as sensitive detector of various gases (gas sensors).

Fig. 5.22 shows the voltage-current characteristics before and after exposure to NO₂.

ii. Nanotubes act as catalysts for some chemical reactions.