Hydrogen storage of capped single-walled carbon nanotube via transition-metal doping

We perform density functional theory (DFT) simulations on the capped-CNT for hydrogen storage, focusing on the coating of the capped-CNT with transition metals (Sc, Co, and Ni). It is demonstrated that the metal atom coated on the surface can store up to four, four, and three molecules, respectively, with significant binding energies in the chemisorption range. At high Sc (Ni) coverage, the hemisphere of the capped-CNT with 30 C atoms is considered to be a promising hydrogen storage device capable of storing 7.08 wt% (5.96 wt%) .