A Computational Study of Endohedral and Exohedral Complexes of Molecular Hydrogen with Single Wall (3, 3) to (6, 6) Armchair Silicon Carbide Nanotubes

A systematic study of a hydrogen molecule adsorbed on three different atomic configurations of armchair silicon carbide nanotubes (SiCNTs) has been performed using hybrid density functional theory. The hydrogen molecule has been adsorbed from both inside as well as from the outer wall of the nanotube. A detailed comparison of the binding energies, equilibrium positions, Mulliken charges of the hydrogen molecule has been performed for all three types of nanotubes and for all possible sites. Our results show that by tuning the tube diameters and the atomic configurations of the SiCNTs, desired binding energy of the adsorbed hydrogen molecule can be obtained. Binding energies of the adsorbed systems indicate that these structures are stable and show site dependence. Specifically, binding energies of the order of 1 eV have been obtained for type 2 (4, 4) structures and a weight capacity of 7.45% has been obtained for type 2 (5, 5) structures.