Theoretical Studies Of Interaction Potentials Between Diatomic Gases And Single Wall Carbon Nanotube

In this paper, applications of single-walled carbon nanotubes (SWNT) to energy storage and chemical sensors are investigated by calculating the interactions between intrinsic/doped SWNT and diatomic gas molecules H2, N2, CO using the density functional theory, and the corresponding potential energy curves are obtained and fitted.Based on the potential energy curves obtained, two conclusions are available:(i) H site of intrinsic SWNT is the most stable adsorption site forH2, N2and CO, one exception, for (9,9) SWNT, the most stable adsorption site for H2is T site,(ii) With increase of the SWNT radius, the adsorption equilibrium distances of the three gases change a little or remain unchanged; whereas variations of the H2、N2and CO adsorption energies with SWNT radius depend on adsorption sites concerned.Dopping CNTs with impurities can change the properties of the CNTs, and in this paper, we dop impurities atoms onto the surface of the SWNT. The calculation results show that (i) transition metals dopping can improve the properties of H2, N2and CO adsorbed on the SWNT.(ii) Compared with the intrinsic carbon nanotubes, the improvement of the CO adsorption property is the most significant by dopping SWNT with transition metals.(iii) Compared with transition metals dopping, the effects of N/B atoms doppings on the adsorption properties are less evident.(iv) One exception is that dopping SWNT with two Boron atoms gives rise to very big effects in improving the adsorption properties of the CO (oxygen atom on the top of carbon atoms), adsorption energy is1.22eV/CO.(v) N/B atoms dopping is not helpful in improving the adsorption properties of the N2.We fit the potential energy curves obtained by LJ and Morse model potentials. It is found that the Morse model potential is very suitable for the fitting, whereas LJ model potential is not qualified for most cases investigated.