High Coverages of Hydrogen on a (10,0) Carbon Nanotube

The binding energy of H to a (10,0) carbon nanotube is calculated at 24, 50, and 100% coverage using the AM1 and ONIOM approaches. Several different bonding configurations are considered for the 50% coverage case. Using the ONIOM approach, the average C−H bond energy for the most stable 50% coverage and for the 100% coverage are 57.3 and 38.6 kcal/mol, respectively. Considering the size of the bond energy of H 2, these values suggest that it will be difficult to achieve 100% atomic H coverage on a (10,0) nanotube. The 50% coverage, which appears favorable, corresponds to about 4% by weight storage of H.