电场中(MgO)_2吸附H_2的理论研究

电场诱导MgO材料吸附H_2是一种有效的储氢方法,而较高的场强制约其广泛应用.本文在B3LYP/CC-PVTZ水平上对电场中(MgO)_2团簇的储氢性质进行了研究,结果表明仅需外加强度为0.005a.u.的电场,就能使其对单个H_2在Mg/O上的吸附能由无电场时的-0.143/-0.091 eV提高到-0.202/-0.134 eV.该场强远小于其他大尺寸MgO材料达到相同吸附强度所需的电场,表明降低材料尺寸是减少储氢所需电场强度的一种可能方法 .计算还表明电场中(MgO)_2最多能吸附8个H_2,相应的质量密度达到16.7 wt%.

Theoretical Study of H2 Adsorption on (MgO)2 under an External Electric Field

The adsorption of H2 on MgO materials under an electric field is an effective hydrogen storage method. However, the intensity of the electric field needed is too high, which limits its wide applications. In this paper, the structure and hydrogen storage properties of (MgO)2 under an external electric field are studied by B3LYP/CC-PVTZ calculations. The results show that an external electric field with the intensity of only 0.005 a. u. can efficiently enhance the adsorption energy of single H2 on the Mg/O from -0.143 /-0.091 eV without an electric field to -0.202/-0.134 eV. The intensity of the electric field needed is greatly smaller than those of MgO materials with larger sized, which indicates that decreasing the sizes of materials can be a potential mothed for reducing the electric field intensities for the hydrogen storage. It is also found that under the electric field, (MgO)2 can adsorb a maximum of 8 H2 molecules, and the corresponding mass density of hydrogen storage reaches 16.7wt%.