Exploring the Crucial Role of Solvation on the Viability of Sustainable Hydrogen Storage in BN-fullerene: A Combined DFT and Ab initio Molecular Dynamics investigation

Realization of practical hydrogen storage in adsorbent materials is still elusive due to several insurmountable issues. In the case of chemical hydrogen storage, the roadblock arises from the failure to attain reversibility of hydrogenation/dehydrogenation under ambient conditions. Herein we show with static and ab initio molecular dynamics (aiMD) methods that the choice of a proper solvent can make monomeric (BN)(24), an experimentally known BN-fullerene, a viable option for sustainable chemical hydrogen storage. A proper thermodynamic and kinetic balance is attained, which prevents oligomerization of monomeric (BN)(24) and affords reversible hydrogenation of the available tetragonal B2N2 rings to appreciable rates and extents. Our calibrated static DFT and canonical (NVT) ensemble aiMD studies indicate that the solvent-(BN)(24) interactions are adequately strong in nucleophilic solvents, while they are fairly weak in electrophilic solvents. We show that hydrogenation of the (micro)solvated monomeric fullerene can be achieved at reasonable rates and to the desired extent in certain solvents using existing metal-free hydrogenating agents. For hydrogenated (BN)(24) the solvent-solute interactions are rather weak in both the nucleophilic and electrophilic solvents, thus making the dehydrogenation less challenging and allowing it to be achieved catalytically. Hence, this endeavor provides the first-ever crucial understanding of the solvation effect on sustainable hydrogenation/dehydrogenation involving BN-fullerenes which is vital for attaining the magic target of over 5 wt % hydrogen storage under ambient conditions.