Interaction of hydrogen with vacancies in a (12,0) carbon nanotube

We perform detailed calculations for the chemical interaction of molecular and atomic hydrogen with single monovacancy and divacancy in a (12,0) carbon nanotube, in the framework of a tight-binding potential model. For the case of monovacancy, the dangling bond in the defect supplies a large cross section to capture either a hydrogen molecule or an atomic hydrogen nearby. The dangling bond site can be hydrogenated in either sp²-like or sp³-like hybridization. Our energetic calculations demonstrate that the void in a monovacancy is not an effective access for the penetration of either atomic or molecular hydrogen between the outer and inner sides of the tube wall, but it could be in a divacancy. These results are of importance in the application of defected carbon nanotubes in the future.