Energetic and structural analysis of N_2H_4BH_3 inorganic solid and its modified material for hydrogen storage

摘要

Here we have exposed the electronic structure, chemical bonding of the light-weight N_2H_4BH_3 inorganic material for hydrogen storage applications and analyzed its hydrogen removal energetics using state-of-the-art first-principles method. The mechanism for the H-host bond weakening in this kind of solid has also been explored. It is shown that the electronic density of states of N_2H_4BH_3 solid near the Fermi level is mainly contributed by the B p-states, H (B) s-states, and the end N p-states. The calculated smallest hydrogen removal energy of N_2H_4BH_3 solid is 4.16 eV. One Li-modified structure has been obtained through ab initio relaxations and its hydrogen removal energies are found dramatically decreased by as much as 50% compared with those of pristine N_2H_4BH_3 solid. The B-H bond weakening is attributed to the elongation of the bond length; for the N-H bonds, the weakening is found to be due to the destabilization of N-H bonds before hydrogen removal and the stabilization of residual N-H bond after hydrogen removal. The weakening of these bonds is of great significance for the improvement of hydrogen desorption kinetics of the material. We propose this study should help to deepen understanding of properties of N2H4BH3 inorganic solid and its related materials for hydrogen storage applications and guide experimentalists and engineers to develop better candidate materials for the advance of the field.