Deformation-induced site selectivity for hydrogen adsorption on boron nitride nanotubes

From first principles, we investigated the adsorption of a hydrogen atom on zigzag single-walled boron nitride nanotubes with and without radial deformation. The adsorption is exothermic. We found that the adsorption energy and site can be modified by the radial deformation. When the deformation is small, H prefers to adsorb on the boron atom, which creates an acceptor state in the gap. However, when the deformation is large enough, H prefers to adsorb on the nitrogen atom in the high curvature region of the radially deformed boron mitride nanotube and creates a donor state. This adsorption and doping behavior can be explained by the frontier-orbital theory and hydrogen level in semiconductors.