Li-decorated porous graphene as a high-performance hydrogen storage material: A first-principles study

Development of novel carbon-based nanoporous materials with high reversible capacity and excellent cycling stability is a hot topic in the field of hydrogen delivery and storage. In this work, first-principles calculations are carried out to discuss the hydrogen storage properties of Li-decorated porous graphene (Li-PG). The binding energies, electronic structures, storage capacities of hydrogen on different sites are investigated in details. The computational results show that with the increase of lithium doping concentration, the electron concentration of donor atoms exceeds the Nc value, and as a consequence, the PG changes from the p-type semiconductor to the n-type degenerate semiconductor. The maximum hydrogen adsorption configurations of H1a-H'1b and H2a-H'2b systems are obtained, and the average binding energy of per H2 molecule is 0.245 eV and 0.263 eV, respectively. Furthermore, ab inito MD simulation results show that the H1-H'1 and H2-H'2 systems can hold up to sixteen and fifteen H2 molecules, which corresponds to a hydrogen storage capacity of 10.89 wt% and 10.79 wt% at T = 300 K (no external pressure), respectively.