Prominently Improved Hydrogen Purification and Dispersive Metal Binding for Hydrogen Storage by Substitutional Doping in Porous Graphene

Abstract

By density functional theory calculations, we demonstrate that the high selectivity for H2 permeability relative to CH4, CO, and CO2 could be fine adjusted by B or N doping in porous graphene (PG), which is very useful for separation of H2 from the mixed gases. Also, the atomically dispersed Li and Ca bindings to the polyphenylene structure are significantly enhanced by B doping. The average binding energies for fully adsorbed Li and Ca atoms on 2B-PG of 1.62 and 1.75 eV are greatly larger than 0.68 and 1.05 eV for pure PG, respectively. It is beneficial to experimental metal decoration since these values exceed the cohesive energies per atom of bulk Li and Ca. Grand canonical Monte Carlo simulations show that the high H2 storage capacities with 6.4 wt % for Li-decorated 2B-PG and 6.8 wt % for Ca-decorated 2B-PG can be obtained at 298 K and 100 bar. Thus, PG through successful controlled synthesis and available doping technology will be expected to achieve the coming hydrogen economy.