Metal functionalized inorganic nano-sheets as promising materials for clean energy storage

The pursuit of a material capable of storing a high capacity of hydrogen (H₂) efficiently has prompted us to study the structural, electronic and H₂ storage properties of recently designed two-dimensional BN₂ nanosheets. Our spin-polarized density functional theory based calculations have revealed that the pristine BN₂ barely anchor H₂ molecules, however, alkali metal (AM) doping enhances the binding energies drastically. Van der Waals corrected energetics analysis established a uniform distribution of AMs over the BN₂ monolayers even at a high doping concentration of 12.50%, which ensure the reversibility of the systems. Bader charge analysis, Roby-Gould bond index method, and electron localization function isosurfaces conclude the transfer of charges from AMs to BN₂, which has resulted into strong ionic bonds between the former and the latter. The presence of partial positive charges on each of the AMs would adsorb multiple H₂ molecules with binding energies that are ideal for mobile H₂ storage applications. Considerably high H₂ storage capacities of 6.75%, 6.87% and 6.55% could be achieved with 3Li@BN₂, 3Na@BN₂ and 3K@BN₂ systems, respectively that guarantees the promise of AMs decorated BN₂ as a promising H₂ storage material.