Theoretical Study of Hydrogen storage with Ti doped B40 boron fullerene

Hydrogen has been considered as one of the most promising energy carrier because of its abundance, cheap and environmental friendliness. It is necessary to develop high capacity hydrogen storage medium. Metal doping has been found to be an effective method to improve hydrogen adsorption ability. B40 fullerene has been considered as promising hydrogen storage material due to its large surface area. In this work hydrogen storage capacity with B40 fullerene doped with titanium (Ti) has been investigated by density functional theory. We have calculated the binding energies of Ti doped endohedrally and exohedrally at the hexagonal and heptagonal cavities. The binding energy calculation shows that the doping of Ti atoms outside the the hollow sites of the B40 structure is most stable. It is observed that the shape and stability of the B40 cage structure rapidly changes with increased number of doping atoms. HOMO-LUMO study predicts that the transport is mainly controlled by LUMO. 5 and 6 H₂ molecules are attached with Ti atoms on each hexagonal and heptagonal holes respectively. From the average hydrogen adsorption energies and nudged elastic band method study, it is observed that most of the interaction is physisorption with weak Vander Waals force interaction.