Theoretical prediction of hydrogen storage on Li decorated planar boron sheets

Highlights: ► Li decorated boron sheets as hydrogen storage media. ► The gravimetric density of H2 is 9.22 wt%. ► The average adsorption energy of hydrogen molecule is 0.35 eV/H2. ► It can operate under ambient thermodynamic conditions. - Abstract: First-principles calculations based on density functional theory are carried out to study the effect of Li decorated boron sheets (BST) on hydrogen storage. The results show that physisorption of H2 molecules on a pristine BST gives a binding energy of ∼0.10 eV/H2, which is too lower for hydrogen storage application. With Li atoms decorated on the both sides of each hexagonal ring, the average binding energy of H2 can reach ∼0.35 eV/H2, acceptable for reversible H2 adsorption/desorption near the room temperature. The maximal hydrogen storage capacity is 9.22 wt%. The enhanced binding energy of H2 molecules on the Li decorated BST can be attributed to the orbital hybridizations and polarization mechanisms.