The structural and electronic properties of Li-doped fluorinated graphene and its application to hydrogen storage

By using first-principles density functional theory, a theoretical investigation of Li-doped fluorinated graphene and its application as a hydrogen storage media is performed. It is found that a mixture between sp3 and a higher degree of sp2 of the carbon orbitals after doping with Li would restore the distorted fluorinated graphene, and a fluorinated graphene layer with Li adsorbed on single or double-sides could store hydrogen up to 9 or 16.2 wt%. Regarding the H2 adsorption mechanism, it has been demonstrated that the enhanced electrostatic field around the Li atom originates from the increased charge transfer from Li to graphene and F atoms with more electronegativity. Hybridization interaction between Li and graphene is also responsible for the adsorption of H2 molecules.

► Density functional theory calculations of Li-doped fluorinated graphene. ► A mixture between sp3 and a higher degree of sp2 of the carbon orbitals after doping Li. ► Dopant of Li restores the distorted fluorinated graphene. ►Li adsorption on single and both sides stores hydrogen up to 9 and 16.2 wt%. ► The moderate binding energy is acceptable for reversible H2 adsorption/desorption.