Theoretical Study of Li-Doped sp2–sp3 Hybrid Carbon Network for Hydrogen Storage

Nanoporous carbon structures are promising candidates for hydrogen physisorption storage due to their high specific area and light weight. Using first-principles calculations, we predict a type of sp2–sp3 hybrid carbon network (HCN) with well-aligned and size-tunable nanopores that are suitable for hydrogen storage. The unique shape of the nanopores is beneficial for the selective Li atoms doping and induces an enhanced H2 binding energy that can be attributed to the improved interaction between polarized H2 and Li ion. A maximum weight percentage of hydrogen storage reaches 6.28 wt % with an average binding energy of −0.19 eV in Li-doped HCN. Together with the ultrahigh volumetric density of hydrogen (102 g/L), the HCN structure is a promising candidate for the hydrogen storage medium.