  Holey graphyne (HGY), a novel 2D single-crystalline carbon allotrope, was
synthesized most recently by Castro-Stephens coupling reaction. The natural
existing uniform periodic holes in the 2D carbon-carbon network demonstrate its
tremendous potential application in the area of energy storage. Herein, we
conducted density functional theory calculation to predict the hydrogen storage
capacity of HGY sheet. It's found the Li-decorated single-layer HGY can serve
as a promising candidate for hydrogen storage. Our numerical calculations
demonstrate that Li atoms can bind strongly to the HGY sheet without the
formation of Li clusters, and each Li atom can anchor four H2 molecules with
the average adsorption energy about -0.22 eV/H2. The largest hydrogen storage
capacity of the doped HGY sheet can arrive as high as 12.8 wt%, this value
largely surpasses the target of the U. S. Department of Energy (9 wt%), showing
the Li/HGY complex is an ideal hydrogen storage material at ambient conditions.
In addition, we investigate the polarization mechanism of the storage media and
and find that the polarization stemed from both the electric field induced by
the ionic Li decorated on the HGY and the weak polarized hydrogen molecules
dominated the H2 adsorption process.
