A first-principles study of hydrogen storage on pristine and Li-decorated superatomic B12N2 monolayers

Abstract

Boron-based nanomaterials have been considered as potential candidates for hydrogen storage due to their unique electronic properties. In this work, we constructed a two-dimensional superatomic B₁₂N₂ monolayer for hydrogen storage by substituting all atoms in T-MoS₂ monolayers with icosahedral B₁₂ units and N atoms. Chemical bonding analysis confirms that the B₁₂ unit follows Wade's rule (2n + 2), exhibiting a 1S²1P⁶1D¹⁰1F⁸ superatomic configuration with 13 highly delocalized twelve-centre two-electron (12c-2e) orbitals. Further studies reveal that the adsorption energy of one H₂ molecule is markedly improved from −0.08 eV (pristine) to −0.33 eV upon Li decoration, driven by polarization via Li-to-monolayer charge transfer. The 2 × 2 × 1 B₄₈N₈ supercell can hold 8 Li atoms and 32 H₂ molecules, achieving a maximum hydrogen storage capacity of 8.60 wt% over the DOE target (6.5 wt%) in 2025. The calculated desorption temperature and molecular dynamics simulations further demonstrate that the Li-decorated B₁₂N₂ monolayer can be regarded as a reversible hydrogen storage material at elevated pressure and/or reduced temperature. Moreover, the importance of zero-point energy effects for hydrogen storage calculation is discussed by comparing the changes in H₂ adsorption ability.