Multiple Ti and Li doped carbon nanoring for hydrogen storage

Abstract

Multiple Ti and Li atom doped carbon nanorings are considered for hydrogen storage using density functional theory for the first time. There are five six membered carbon rings bonded through C–C bond in a carbon nanoring. Formation energy values show that both, Li as well as Ti atom doped carbon nanoring, are thermodynamically stable structures. Cohesive energy values indicate that Li and Ti atom doped carbon nanoring structures are more stable than undoped carbon nanoring. No clustering of metal atoms occurs in metal doped carbon nanorings which usually reduces the hydrogen storage capacity of a material. Li atom doped carbon nanoring is not suitable for hydrogen storage even at very low temperature at 1 atm pressure as well as at high pressure at room temperature. Ti atom doped carbon nanoring is suitable for hydrogen storage below 225 K and 1 atm pressure as well as at high pressure at room temperature. H2 desorption temperature is found to be 113 and 450 K for Li and Ti atom doped carbon nanoring respectively. H2 molecules interact strongly with Ti atom doped carbon nanoring than Li atom doped carbon nanoring that results in higher H2 desorption temperature for the former than the latter.