Metal-decorated carbon-doped BN fullerenes as highly efficient materials for solid-state hydrogen storage: insights from DFT calculations

Abstract

This research investigates the potential of Li- and Sc-decorated carbon-doped B₁₂N₁₂ nanocages for reversible hydrogen (H₂) storage, utilizing density functional theory calculations. The introduction of carbon at boron or nitrogen sites substantially improves the electronic structure of the BN fullerene, with the replacement of nitrogen atoms by carbon being energetically more favorable. The incorporation of these carbon impurities significantly enhances the adsorption of metal atoms onto the BN structure. The findings indicate that up to eight Li or four Sc atoms can be accommodated on the hexagons of the B₁₂C₁₂ nanocage. The adsorption energies for H₂ molecules on the Li₈@B₁₂C₁₂ system range from −0.24 to −0.20 eV, while on the Sc₄@B₁₂C₁₂ structure, they range from −0.25 to −0.21 eV. The hydrogen storage capacities for these systems are 12.7 wt% and 6.6 wt%, respectively. While polarization effects are the primary driving force for H₂ adsorption on the Li₈@B₁₂C₁₂ nanocage, Kubas-type orbital interactions serve as an additional factor for H₂ adsorption on the Sc₄@B₁₂C₁₂ counterpart. Furthermore, the metal-decorated B₁₂C₁₂ nanocages exhibit desorption temperatures between 263 and 349 K. Additional calculations of occupation numbers, along with molecular dynamics simulations, support the conclusion that the H₂ molecules stored on the metal-decorated B₁₂C₁₂ fullerenes can be released at moderate temperatures and pressures. This theoretical study suggests that Li- and Sc-decorated carbon-doped BN materials may be efficient candidates for hydrogen storage and provides potential pathways for effective hydrogen storage under ambient conditions.