Computational Study of the Effect of Adsorbed Lithium on Solid State Hydrogen Storage Capacity of Pristine and Boron Doped Graphene

Abstract

Hydrogen is considered one of the most promising source of clean and renewable energy as an alternative for environment polluting fossil fuel resources. The safe and reasonable volumetric density storage represent the main problem facing the hydrogen technology. Most of the research nowadays are focusing on development of new technologies for solid state storage of hydrogen. At the present study, The adsorption of hydrogen molecule (H2) has been studied on the supercell (3 x 3 x 1) of pure graphene and doped graphene  with boron atom and adsorbed with lithium atom by first principle calculations with DFT method. We choice local density approximation (LDA) To describe the exchange-correlation energy between the interacting electrons and the basis set (Double Numerical Plus polarization DNP), the regions of a Brillion zone are set to (2 x 2 x 1). The binding energy of hydrogen molecules adsorbed on the surface of graphene adsorbed by the lithium atom was between (0.2-0.4 eV) and with a storage ratio (6.74 wt.%), Which meets the gravitational capacity standard specified by the energy department, And the binding energy of hydrogen molecules adsorbed on the surface of graphene adsorbed by the lithium atom and doped with the boron atom was between (0.23-0.32 eV) and with a storage ratio (6.67 wt.%), Thus meeting the standard for the final mass capacity (6.5 wt.%) Specified by the Department of Energy.  We conclude that the doping of the boron atom into one of the six graphene rings in the large unit cell (3 × 3 × 1) played a major role in increasing the stability of the graphene surface and reduce the binding energy that contributes to reducing the temperature of the hydrogen desorption process.