Grand canonical Monte Carlo simulation study of hydrogen storage by Li-decorated pha-graphene

Grand canonical Monte Carlo simulation (GCMCs) is utilized for studying hydrogen storage gravimetric density by pha-graphene at different metal densities, temperatures and pressures. It is demonstrated that the optimum adsorbent location for Li atoms is the center of the seven-membered ring of pha-graphene. The binding energy of Li-decorated pha-graphene is larger than the cohesive energy of Li atoms, implying that Li can be distributed on the surface of pha-graphene without forming metal clusters. We fitted the force field parameters of Li and C atoms at different positions and performed GCMCs to study the absorption capacity of H-2. The capacity of hydrogen storage was studied by the differing density of Li decoration. The maximum hydrogen storage capacity of 4Li-decorated pha-graphene was 15.88 wt% at 77 K and 100 bar. The enthalpy values of adsorption at the three densities are in the ideal range of 15 kJ.mol(-1)-25 kJ.mol(-1). The GCMC results at different pressures and temperatures show that with the increase in Li decorative density, the hydrogen storage gravimetric ratio of pha-graphene decreases but can reach the 2025 US Department of Energy's standard (5.5 wt%). Therefore, pha-graphene is considered to be a potential hydrogen storage material.