Lithium and sodium decorated PHE-graphene for high capacity hydrogen storage: A DFT and GCMC study

Abstract

Porous nanocarbon materials are seen as potential excellent materials for hydrogen storage due to their high surface area, excellent cycling stability and favorable kinetics. This study employs Density Functional Theory (DFT) simulations to investigate key property of Li$^-$ and Na$^-$ modified PHE-graphene, including structural stability, electronic properties, and hydrogen storage capabilities. The results show that when each Li atom adsorbs six hydrogen molecules, the material reaches the maximum hydrogen adsorption gravimetric density of 15.20 wt%. Additionally, through Grand Canonical Monte Carlo (GCMC) simulations, we obtained the hydrogen weight ratios and adsorption enthalpy curves for Li- and Na-modified PHE under varying temperature and pressure conditions. These findings indicate that both Li- and Na-modified PHE-graphene are exceptional candidates for hydrogen storage materials, particularly in mobile applications.