Metal decorated carbon-doped BN fullerenes as highly efficient materials to 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 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 introduction of 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 hydrogen molecules in the Li8@B12C12 system range from -0.24 to -0.20 eV, while in 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 a primary driving force for H2 adsorption on the Li8@B12C12, Kubas-type orbital interactions serve as an additional factor for H2 adsorption on the Sc4@B12C12. 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 hydrogen 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 for hydrogen storage and offers potential improvements for effective hydrogen storage under ambient conditions.