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.
Highlights
The development of human society faces the severe challenge of environmental pollution, which is urgently needed to explore more ideal energy materials to meet the growing energy demand [1,2,3].Hydrogen (H2 ) is used as a promising energy carrier because of recycling, no pollution, high energy density and high calorific value [4,5,6]
The largest hydrogen storage capacity structure was two Sc atoms located at two sides of the boron-carbon hexagon center in the Sc-B/porous graphene (PG) system
Where EB/PG is the energy of the doped porous graphene, nC, nH and nB are the number of C, H
Summary
The development of human society faces the severe challenge of environmental pollution, which is urgently needed to explore more ideal energy materials to meet the growing energy demand [1,2,3]. Transition metal atoms [20,21] modified graphene has attracted researchers’ attention since significantly increasing the adsorption energy of H2 molecules. The transition metal atoms Sc, Ti and V decorated on both sides of graphene could adsorb four H2 molecules with an average adsorption energy of. The transition metal atom modified graphene is prone to aggregation, which reduces the adsorption site of H2 and weakens the hydrogen storage performance of graphene. Molecules 2019, 24, 2382 transition metal atoms and increase the hydrogen storage capacity of graphene [24]. 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
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