High Capacity Hydrogen Storage in Li Decorated Octagraphene - A First Principles Study

Abstract

From first principles density functional theory, Li-decorated octagraphene and its usage as a hydrogen storage media is theoretically investigated. Octagraphene is a versatile structure with periodic sp2 – bonded carbon atomic planar sheet. This carbon allotrope consists of carbon octagons and rectangular lattices with two bond lengths. The Li binding energy in octagraphene is 2.5 eV, which is much higher than that of pristine graphene. Maximum of four hydrogen molecules can be adsorbed on Li decorated on one side of octagraphene and this leads to a gravimetric storage capacity of 2.4 wt% with an average adsorption binding energy of 0.35eV/H2. Li decorated on both sides of octagraphene, attains a gravimetric storage capacity of 8.1 wt% with an average binding energy of 0.23 eV/ H2. Thus, the structure investigated here is flattering for the reversible hydrogen adsorption/ desorption at the room temperature.