Abstract
The generalized gradient approximation (GGA) function based on density functional theory is adopted to investigate the optimized geometrical structure, electron structure and hydrogen storage performance of Sc modified porous graphene (PG). It is found that the carbon ring center is the most stable adsorbed position for a single Sc atom on PG, and the maximum number of adsorbed H2 molecules is four with the average adsorption energy of −0.429 eV/H2. By adding a second Sc atom on the other side of the system, the hydrogen storage capacity of the system can be improved effectively. Two Sc atoms located on opposite sides of the PG carbon ring center hole is the most suitable hydrogen storage structure, and the hydrogen storage capacity reach a maximum 9.09 wt % at the average adsorption energy of −0.296 eV/H2. The adsorption of H2 molecules in the PG system is mainly attributed to orbital hybridization among H, Sc, and C atoms, and Coulomb attraction between negatively charged H2 molecules and positively charged Sc atoms.
Highlights
Considerable research has been conducted to search for clean, renewable energy to meete growing energy demand [1]
U.S Department of Energy (DOE) and the International Energy Agency (IEA), the desirable hydrogen storage capacity of a promising material should be greater than 5.5 wt %
We study the adsorption of one Sc atom atom on on porous graphene (PG)
Summary
Considerable research has been conducted to search for clean, renewable energy to meete growing energy demand [1]. Code within the GGA functional calculation, because each Sc atom could adsorb five H2 molecules with the adsorption energies from 0.2 to 0.4 eV. Using the DMol package within the LDA functional calculation, Y decorated B-doped graphene was studied as a potential carrier for hydrogen storage, in which the hydrogen storage capacity was 5.78 wt %. Reunchan et al [34] investigated the Ca-decorated PG and found that an isolated Ca atom could adsorb five hydrogen molecules with the average adsorption energy of 0.230 eV. Yuan et al [35] studied Y-decorated porous graphene and they found that the maximum number of adsorbed hydrogen molecules around the Y atom was six and the average adsorption energy was −0.297 eV. The adsorption properties and adsorption mechanism of H2 molecules on the Sc decorated PG system are analyzed to better understand the effect of Sc atoms modified PG on the hydrogen storage properties
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