Chemisorption of Hydrogen Molecules on Carbon Nanotubes under High Pressure

Based on first principles calculations, we propose a mechanism for the dissociative chemisorption of $H_2$ on carbon nanotubes. The breaking of the H—H bond is concerted with the formation of two C—H bonds on two adjacent carbon nanotubes in solid phase, facilitated by the application of high pressure which shortens the interstitial distance between nanotubes. The process is reversible upon the release of external pressure and could make an important contribution to the observed hydrogen storage capacity of carbon nanotubes. The previously unexplained experimental observations of the direct hydrogenation of fullerenes under high pressure lend further support for such a mechanism.