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Description
This article presents the hydrogen storage capacity of Ar
encapsulated and Li functionalized Si12C12heterofullerene using state-of-the-art Density Functional Theory (DFT) simulations. We find that the Li
atom regioselectively prefers to bind at the top of the tetragonal sites of Ar
encapsulated Si12C12 heterofullerene with a maximum binding energy of
2.02 eV. Our study reveals that inert gas Ar encapsulation inside bare
Si12C12 provides greater stability to the heterofullerene by reducing the
distortion. Hence, it provides a steady platform for Li decoration and
successive H2 adsorption. The adsorption energies of sequentially
hydrogen-adsorbed Si12C12Li6,Ne@Si12C12Li6,and Ar@Si12C12Li6 are
compared, and it is observed that H2 molecules prefer to adsorb over Li
decorated Ar@Si12C12 with maximum adsorption energy. Each Li atom
decorated over Ar@Si12C12 adsorbs a maximum of 5H2 molecules with an
optimum adsorption energy of 0.11−0.22eV,resulting in a gravimetric density of 9.7wt% which is well above the US-DoE target. The adsorption mechanism of H2 molecules over Ar@Si12C12Li6 has been thoroughly investigated using the electrostatic map and topological analyses. The type of interaction involved in the adsorption of H2 molecules over the Ar@Si12C12Li6 surface is found to
be a weak noncovalent interaction. Thermodynamic study reveals that almost all the 30H2 molecules remain adsorbed over the
system at a low temperature of 100−120K and undergo maximum desorption at 250−400K, maintaining the structural integrity,
which infers that the Ar@Si12C12Li6 nanocage can be considered as a potential hydrogen storage material.
KEYWORDS: heterofullerene, encapsulation, functionalization, adsorption, gravimetric density, noncovalent
