The electric field effect on the hydrogen storage properties of (MgO)9

Abstract ( MgO ) 9 with a rocksalt structure, a magic number cluster of ( MgO ) n , exhibits high stability. In this study, the hydrogen storage properties of ( MgO ) 9 under an external electric field are explored by DFT calculation. The results reveal that H 2 can be adsorbed on single Mg/O atoms. Because the ( MgO ) 9 and H 2 are effectively polarized by the external electric field, the adsorption strength of H 2 at certain adsorption sites is substantially enhanced. The adsorption energies of H 2 on three-coordinated Mg/O atoms increase from −0.071/−0.056 eV in the absence of an electric field to −0.186/−0.237  eV under a field intensity of 0.025 a.u. Under the field, ( MgO ) 9 can adsorb a maximum of 18 H 2 molecules, and the corresponding mass density of hydrogen storage reaches 9.1 wt%. Our results suggest that subjecting the ( MgO ) 9 to an external electric field is a potential hydrogen storage method. In this paper, the interaction mechanism between H 2 and ( MgO ) 9 under the external electric field is also investigated through an electronic structure analysis.