Hydrogen Storage in Sc and Li Decorated Metal-Inorganic Framework

Hydrogen is a versatile, clean, and efficient energy carrier considered as an ideal substitute for a future energy source in the automobile industry. A metal-inorganic framework with borazocine (BN) linker resulting in a metal-BN framework (MBF) has been studied for hydrogen storage. Borazocine (B₄N₄H₈) is decorated with metals, M (Sc, Li), and studied the stability and hydrogen storage capacity. Density functional theory with generalized gradient approximation and Perdew-Burke-Ernzerhof functional with double numeric polarized basis set augmented with p-function are used to explore the structural stability, and hydrogen sorption kinetics of metal decorated MBF. It is observed that each Sc and Li physisorbed 4 and 3 H₂ molecules, respectively. The BN ring binds with metals (Sc and Li) by Dewar coordination while the metal atoms adsorb H₂ molecules by the Kubas-Niu-Rao-Jena mechanism. Molecular dynamics simulations show that the Sc decorated MBF system is stable and the adsorbed hydrogen is reversible at ambient conditions. The low sorption energies indicate that the Sc decorated MBF system is an ideal hydrogen storage material. The H₂ storage capacity is found to be 7.80 and 8.25 wt % for Sc and Li decorated MBF, respectively. The high hydrogen wt % indicates that the metal decorated framework is a potential hydrogen storage material.