Lithium-Decorated Borospherene B40: 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 - n H 2 system differs markedly from the previous Li-C 60 - n H 2 and Ti-B 40 - n H 2 complexes.