A first-principles study of Calcium decorated on the interlayer of bilayer graphene for high capacity hydrogen storage

On the basis of the adsorption of hydrogen on the monolayer grapheme, the hydrogen storage properties of the bilayer grapheme were studied. The paper makes a simulation analysis of the hydrogen storage capacity of the calcium-decorated bilayer grapheme using the first principles based on density functional theory. The layer spacing between the double layers of grapheme was regulated by doping CA element. The optimal adsorption model of hydrogen storage of the bilayer grapheme was simulated using the vast package. Ultimately, the binding energy of hydrogen meets the U.S. department of energy's range of -0.2eV to -0.6eV. CA can adsorb on the interlayer of bilayer grapheme without clustering and have high hydrogen storage capacity. The empty pp. orbital of boron is used as a strong charge receptor, thus improving the adsorption capacity of CA on bilayer grapheme. The stability of the modified system and the excellent hydrogen storage performance are obtained through the simulation calculation. The system can adsorb up to 8 hydrogen molecules. The average binding energy of -0.2eV∼0.3 eV/H2 is in the range that permits H2 recycling at ambient conditions. Calculation and analysis of the adsorption energy and state density in the adsorption process explained the hydrogen storage mechanism of bilayer grapheme. (paper)