Scandium Decoration of Boron Doped Porous Graphene for High-Capacity Hydrogen Storage

Abstract

The hydrogen storage properties of the Scandium (Sc) atom modified Boron (B) doped porous graphene (PG) system were studied based on the density functional theory (DFT). For a single Sc atom, the most stable adsorption position on B-PG is the boron-carbon hexagon center after doping with the B atom. The corresponding adsorption energy of Sc atoms was −4.004 eV. Meanwhile, five H2 molecules could be adsorbed around a Sc atom with the average adsorption energy of −0.515 eV/H2. Analyzing the density of states (DOS) and the charge population of the system, the adsorption of H2 molecules in Sc-B/PG system is mainly attributed to an orbital interaction between H and Sc atoms. For the H2 adsorption, the Coulomb attraction between H2 molecules (negatively charged) and Sc atoms (positively charged) also played a critical role. The largest hydrogen storage capacity structure was two Sc atoms located at two sides of the boron-carbon hexagon center in the Sc-B/PG system. Notably, the theoretical hydrogen storage capacity was 9.13 wt.% with an average adsorption energy of −0.225 eV/H2. B doped PG prevents the Sc atom aggregating and improves the hydrogen storage effectively because it can increase the adsorption energy of the Sc atom and H2 molecule.