Study on oxygen and nitrogen adsorption in carbon nanotube

Single walled carbon nanotubes (SWCNT) as well as oxygen and nitrogen adsorption are studied by density function and discrete variational (DFT-DVM) method, one of the first principle calculation methods. Several models with difference lengths and calibers are studied to discuss the length and section of SWCNT that affects the properties. Different types of adsorption models are optimized based on the energy minimization. There are some strong ionic and covalent interactions among carbon atoms, and between carbon and nitrogen or oxygen atoms. As the length of the SWCNT increases, the charges of the middle and top (or bottom) carbon layers decrease. The larger the length and section of SWCNT is, the stronger the adsorption between SWCNT and gas is. It is shown that oxygen adsorption in SWCNT increases carbon nanotubepsilas electrical conductivity more obvious than nitrogen adsorption, which is consistent with the experiments.