Theoretical exploration of the LiF-decorated BN cages as hydrogen storage materials

Density functional theory calculations were applied to investigate LiF decoration of B12N12 cage in terms of the structures and stabilities. Then, the resulted LiF-decorated B12N12 cages were explored to find their capability as hydrogen storage. The DFT results showed that decoration of BN cages is independent of the previously decorated BN bonds. LiF decoration of BN bonds leads to charge redistribution so that charges of the atoms nearest to the decorated bonds change and charges of the other ones remain rather unchanged. Hydrogen prefers to bind to the B atoms that are nearest to the decorated Li. It was revealed that H atoms bind more strongly to B atoms of LiF-decorated B12N12 cages in comparison to pristine B12N12 cage. Two types of hydrogen bonding were formed in B12N12Li4F4 and B12N12Li6F6, binding of hydrogens in a quasi-molecular form to the decorated Li atoms, and also binding of hydrogen in atomic to B atoms. Calculated binding energies showed that binding of hydrogen to the models is an intermediate between physical and chemical adsorption, indicating that the LiF-decorated B12N12 cages are suitable as hydrogen storage materials.