Adsorption of hydrogen molecules onto Li-decorated titanium met-car cluster: A first-principles study

The hydrogen storage capacity of the Li-decorated titanium metallocarbohedryne (Ti met-car) cluster has been investigated by using density functional theory calculations. It is found that Li atom prefers to be adsorbed above the trigonal hollow site between C and Ti atoms with an average binding energy of about −1.75 eV. We show that the media produced by 12 Li atoms coated on the cluster can store up to 36 hydrogen molecules resulting in the gravimetric density of about 10.55 wt%. The binding energy of about −0.37 eV/H2 for such a system allows H2 recycling at ambient conditions. Interestingly, the adsorption behavior of 36 H2 molecules around the 12 Li-decorated Ti met-car system has been investigated through ab initio MD simulation at room temperature. Our result showed that hydrogen molecules escape from the cage, which highlights that the corresponding system facilitates the hydrogen desorption at ambient conditions for practical applications.

► Hydrogen storage capacity of Li-decorated Ti-met-car was investigated.
► DFT calculations were implemented for the considered systems.
► Full structural optimization was performed for all the systems.
► The Ti-met-car media results in gravimetric density of 10.55 wt%.
► Ab initio MD simulation was performed for desorption of hydrogen.