Lithium-Decorated Borospherene B(40): A Promising Hydrogen Storage Medium

The recent discovery of borospherene B(40) marks the onset of a new kind of boron-based nanostructures akin to the C(60) buckyball, offering opportunities to explore materials applications of nanoboron. Here we report on the feasibility of Li-decorated B(40) for hydrogen storage using the DFT calculations. The B(40) cluster has an overall shape of cube-like cage with six hexagonal and heptagonal holes and eight close-packing B(6) triangles. Our computational data show that Li(m)&B(40)(1–3) complexes bound up to three H(2) molecules per Li site with an adsorption energy (AE) of 0.11–0.25 eV/H(2), ideal for reversible hydrogen storage and release. The bonding features charge transfer from Li to B(40). The first 18 H(2) in Li(6)&B(40)(3) possess an AE of 0.11–0.18 eV, corresponding to a gravimetric density of 7.1 wt%. The eight triangular B(6) corners are shown as well to be good sites for Li-decoration and H(2) adsorption. In a desirable case of Li(14)&B(40)-42 H(2)(8), a total of 42 H(2) molecules are adsorbed with an AE of 0.32 eV/H(2) for the first 14 H(2) and 0.12 eV/H(2) for the third 14 H(2). A maximum gravimetric density of 13.8 wt% is achieved in 8. The Li-B(40)-nH(2) system differs markedly from the previous Li-C(60)-nH(2) and Ti-B(40)-nH(2) complexes.