Li-decorated octagonal-distorted-graphene as a high-capacity near-ambient hydrogen storage medium: A first-principles study

Two-dimensional (2D) porous carbon allotropes have emerged as promising solid-state media for hydrogen storage; yet, achieving high gravimetric capacity with near-ambient reversibility remains challenging. Here, we investigate hydrogen adsorption on lithium-decorated Octagonal-Distorted-Graphene (Li@OCD-graphene) using density functional theory (DFT) calculations, including dispersion corrections, charge analysis, and ab initio molecular dynamics (AIMD). Lithium preferentially binds to hollow/porous regions of the OCD framework with substantial charge transfer (Bader analysis), enabling the electrostatic polarization of adsorbed H 2 molecules. Stepwise double-sided loading indicates that Li@OCD-graphene can accommodate up to 32 H 2 molecules per considered supercell (Li:H 2 = 1:4), yielding a maximum hydrogen adsorption capacity of 10.74 wt%. The average adsorption energies remain within a moderate range of − 0 . 22 to − 0 . 26 eV per H 2 , consistent with physisorption-driven storage and favorable near-room-temperature release. Estimated desorption temperatures span 276–325 K at 1 atm and extend up to ∼ 436 K under higher pressures (1–10 atm). AIMD simulations at 300 K further support practical reversibility, showing spontaneous H 2 desorption while preserving the integrity of the Li@OCD-graphene host and maintaining H–H bond lengths close to the molecular value. • Li-decorated OCD-graphene stores up to 10.74 wt% H 2 at near-ambient conditions. • Moderate H 2 binding energies enable reversible adsorption and release. • AIMD confirms thermal stability and spontaneous H 2 desorption at room temperature.