First principles design of Li functionalized hydrogenated h-BN nanosheet for hydrogen storage

Abstract

Employing first principles density functional theory (DFT) based approach, the structure, stability and hydrogen storage efficiency of a hydrogenated hexagonal boron nitride sheet (BHNH chair conformer) functionalized by the lightest alkali metal atom Li has been explored here in details. Substituting one hydrogen atom from both B and N sides of BHNH sheet by a Li atom, we have found that Li becomes cationic and acts as a binding site to adsorb hydrogen molecules. The stability of this Li-substituted BHNH sheet has been indicated via Ab-initio Molecular Dynamics (AIMD) simulation upto 400 K. The binding energy (∼0.18–0.3 eV/H2 molecule) and gravimetric density (∼6 wt %) (upto ∼200 K) of the hydrogen molecules fall in the required window for practical hydrogen storage. AIMD simulation indicates complete dehydrogenation from this system occurs at ∼400 K, thereby predicting the suitability of this system from the point of view of efficient hydrogen storage.