Li-decorated porous hydrogen substituted graphyne: A new member of promising hydrogen storage medium

Two dimensional porous hydrogen substituted graphyne (HsGY), a new member of carbon allotropes, has been synthesized recently (Yang et al., 2019). Here, the hydrogen storage behaviors of Li-decorated HsGY are investigated by using the first-principles calculations. It is found that the Li atom prefers to adsorb over the center of a hexagon ring with the binding energy of - 1.91 eV. The interaction between Li and HsGY is attributed to the hybridization and polarization mechanisms. Each Li atom can attach at most four H-2 without dissociation of H-2 molecule. For double-side Li-decorated HsGY, the H-2 gravimetric density can reach up to 11.35 wt%, with the average adsorption energy of -0.25 eV/H-2. Our numerical results reveal Li-decorated HsGY could be considered as a new potential H-2 storage medium.