Theoretical study of the binding energy of some gases on Al-doped carbon nanotube

Adsorption of a single molecule of the gases, H2O, NH3 and HF inside and on the surface of a tube of Al-doped (5,0) single-walled carbon nanotubes (Al-CNT) was investigated using Density Functional Theory (DFT) at the B3LYP/6-31G(d) level. The results showed that adsorption of Al-CNT is independent of special orientation, all guest molecules prefer to be adsorbed into the surface of Al-CNT rather than into the CNT tube, and that HF binds stronger than H2O, which binds stronger than NH3. Upon adsorption of the guest molecules, the energy gap of Al-CNT was considerably reduced, resulting in improved electrical conductivity. DOS and NBO analysis were performed to discover intermolecular interactions. Chemical reactivity was investigated in terms of chemical hardness, softness and absolute electronegativity. Keywords: Al-CNT, Density Functional Theory (DFT), DOS, NBO, Hardness, Softness, MO orbital