Ultrahigh capacity and reversible hydrogen storage media based on Li-decorated T-BN monolayers

Abstract

The hydrogen storage performance of Li decorated BN monolayer (simply T-BN) composed of repeating octagons and tetragons (only including one element) were explored by using DFT+D calculations. The Li atoms are decorated steadily on the T-BN monolayer without any clustering, which has been confirmed by binding energy per Li (>2.68 eV), transition states search and phonon dispersion. H 2 molecules interacting with the Li-decorated monolayer is of electrostatic nature. The Li-decorated T-BN monolayers have an ultrahigh hydrogen adsorption capacity of 12.31 wt% with adsorption strength of 0.245– 0.315 eV/H 2 , almost twice over the U.S. DOE target (6.5 wt%) and much larger than that of most of BN nanostructures . In addition, desorption temperature ( T D ), adsorption number of H 2 at practical operating conditions, and MD simulations were studied to confirm the reversibility of the Li-decorated BN monolayers as hydrogen storage media. The T D for H 2 at 1 atm is in the range of 180– 232.6 K, which would increase with the pressure increasing. In particular, the condition at 30 atm and under 200 K (or 3 atm and above 350 K) could be undoubtedly ideal adsorption (or desorption) condition, which is properly advantageous to the hydrogen-based fuel cell vehicle applications. Our findings thus reveal that the Li-decorated T-BN monolayers are extremely hopeful candidates for reversible and ultrahigh-capacity hydrogen storage media.