International Journal of Hydrogen Energy, Vol.45, No.23, 12932-12939, 2020
Ultra-high capacity hydrogen storage of B6Be2 and B8Be2 clusters
The B6Be2 and B8Be2 clusters, adopting fascinating inverse sandwich-like geometries, were recently predicted with quantum chemical calculations. Both systems exhibit the high stability and double aromaticity with 4 sigma/6 pi or 6 sigma/6 pi delocalized electrons. The hydrogen storage of two systems is studied in the present paper. Our calculations show that B6Be2 and B8Be2 clusters have the ultra-high capacity hydrogen storage, each Be site can bound up with seven H-2 molecules, corresponding to a gravimetric density of 25.3 wt percentage (wt%) for B6Be2 and 21.1 wt% for B8Be2, respectively, which far exceeds the target (5.5 wt%) proposed by the US department of energy (DOE) in 2017. The average absorption energies of 0.10-0.45 eV/H-2 for B6Be2 and 0.11-0.50 eV/H-2 for B8Be2 at the wB97XD level suggest that both systems are ideal for reversible hydrogen storage and release. The reversibility of H2 molecules on B6Be2 and B8Be2 complexes are faithfully demonstrated with the Born-Oppenheimer molecular dynamics (BOMD) simulations. The Be-doped boron nanostructure is a promising candidate for ultra-high hydrogen storage materials. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.