Yttrium decorated fullerene C30 as potential hydrogen storage material: Perspectives from DFT simulations

Using the density functional theory method, hydrogen storage capacity for Yttrium doped fullerene has been studied. Bonding of Y atom with that of C-30 is due to the charge transfer taking place from the d-orbital of the Y atom to the 2p-orbital of the C atom of C-30. It has been predicted that a single Y atom can adsorb 7 hydrogen molecules, whose binding energy falls within the range as suggested by the U.S. Department of Energy (DOE). Interaction of hydrogen on the metal is because of the Kubas interaction where charge donation occurs from the metal d-orbital to the hydrogen 1s-orbital and there is also back donation as a result the hydrogen adsorption energy is more than physisorption. However, H atoms in the H-2 molecule is not getting dissociated, only a small elongation of H-H bond in the H-2 molecule is observed. The gravimetric weight percentage for 5 Y atoms loaded fullerene C-30, with each Y atom adsorbing 7 H-2 molecules is recorded to be 8.060%, higher than the limit of 6.5% by DOE. These findings suggest Y doped fullerene C-30 may be considered as a potential candidate for hydrogen storage devices.