title: Boron-double-ring sheet, fullerene, and nanotubes: potential hydrogen storage materials.
abstract: Similar to carbon-based graphene, fullerenes and carbon nanotubes, boron atoms can form sheets, fullerenes, and nanotubes. Here we investigate several of these novel boron structures all based on the boron double ring within the framework of density functional theory. The boron sheet is found to be metallic and flat in its ground state. The spherical boron cage containing 180 atoms is also stable and has I symmetry. Stable nanotubes are obtained by rolling up the boron sheet, and all are metallic. The hydrogen storage capacity of boron nanostructures is also explored, and it is found that Li-decorated boron sheets and nanotubes are potential candidates for hydrogen storage. For Li-decorated boron sheets, each Li atom can adsorb a maximum of 4 H2 molecules with g(d) =7.892 wt %. The hydrogen gravimetric density increases to g(d) =12.309 wt % for the Li-decorated (0,6) boron nanotube.
authors.affiliation: Department of Physics and Hebei Advanced Thin Film Laboratory, Hebei Normal University, Shijiazhuang 050016, Hebei (China), Fax: (+86) 311-80787338; State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China).
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Hui-Yan
authors.initials: HY
authors.lastname: Zhao
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
keywords: boron nanotubes; boron sheets; density functional calculations; hydrogen storage; nanostructures