Molecular dynamic simulation of high-quality hydrogen storage in pillared bilayer graphene bubble structure

Abstract

The storage of molecular hydrogen in a novel 3D carbon structure – pillared graphene bubble system under various environments is calculated using molecular dynamics (MD) method. The graphene-based structures are designed with different sizes of semi-ellipsoidal graphene bubbles. The effects of pressure, temperature, and graphene interlayer spacing are systematically investigated in the isothermal–isobaric (NPT) ensemble. Meanwhile, the internal pressures of molecular hydrogen in bubbles under various environments are also estimated. Results show that the hydrogen storage capacity of the pillared graphene bubble structures can be maximized by decreasing the temperature and increasing the pressure and the graphene interlayer spacing. The MD simulations demonstrate that the maximum gravimetric and volumetric H2 densities inside the developed system are 13.7wt% and 121.6kg/m3, respectively. Impressively, the maximum gravimetric and volumetric H2 densities of the developed system are also calculated – 21.3wt% and 210.3kg/m3, respectively, when the outer surface adsorption are taken into consideration. These values satisfy the requirements for mobile applications set by the U.S. Department of Energy (DOE).