“Influence of point defects on the hydrogen storage in nickel decorated GeC and SnC nanotubes’’

Abstract

The density functional theory (DFT) calculations were performed to investigate the structures, electronic properties, and hydrogen-storage capacity of Ni- decorated GeCNT and SnCNT, as well as the effect of Ge, Sn and C vacancies on hydrogen storage capacity. The functionalized Ni is found to be adsorbed on GeCNT, SnCNT, GeCVCNT and SnCVCNT with an adsorption energy of −6.453, −3.780, −5.794 and −4.845 eV. The functionalized GeCNT, SnCNT, GeCVCNT and SnCVCNT bind up to seven, four , five and four hydrogen molecules with the adsorption energy of (-0.236, −0.208, −0.221 and −0.201 eV). The GeCNT, SnCNT, GeCVCNT and SnCVCNT systems exhibit a maximum gravimetric storage capacity of 8.963, 4.083, 6.582 and 4.089 wt%. Our calculations show that nH2NiGeCVGe and nH2NiSnCVSn system is not a suitable use for hydrogen storage. Therefore, Ni-decorated GeCNT, SnCNT, GeCVCNT and SnCVCNT nanotubes are promising candidate materials for use as hydrogen storage material.