碱金属钠原子修饰硅原子团簇的结构及储氢性能研究
Structures and hydrogen storage properties of the alkali metal sodium atoms decorated silicon atoms clusters

提出碱金属钠原子修饰笼形Si6团簇的结构模型, 采用密度泛函理论(DFT)研究钠原子修饰笼形Si6团簇的结构及储氢性能. 研究结果表明, 氢分子与笼形Si6团簇表面相互作用很弱, 氢分子在其表面容易脱附. 采用钠原子修饰笼形Si6团簇后可有效避免氢分子的脱附, 并且钠原子在笼形Si6团簇的表面不发生团聚, 有利于氢分子在其表面吸附和循环利用. 研究发现在两个钠原子修饰笼形Si6团簇的结构中, 每个钠原子可以有效吸附六个氢分子. 计算得到Na2Si6团簇结构储氢的质量分数高达10.08wt%, 且氢分子的平均吸附能约为0.837 kcal/mol. 可见, 实现钠原子修饰笼形Si6团簇结构在常温常压条件下储氢是有可能的.
The model of alkali metal sodium atoms decorated Si6 cage clusters of Na-Si6-Na was proposed. Using the density functional theory (DFT) to study the structures and hydrogen storage properties of the sodium atoms decorated Si6 cage clusters. All the calculations were processed based on 6-311+G(d, p) set basis. Theoretical research results show that the interaction between the hydrogen molecules and the pure Si6 cage was so weakened that the hydrogen molecules desorbing from the surface of Si6 cage. However, using sodium atoms decorated the surface of Si6 cage can avoid hydrogen molecules desorbed from Si6 cage surface and sodium atoms did not clustering together on the surface of Si6 cage, which is beneficial for hydrogen molecules adsorption cycle. The results show that each sodium atom can adsorb effectively six hydrogen molecules for two sodium atoms decorated Si6 cage cluster structure. The calculated gravimetric density of hydrogen reaches as high as 10.08 wt%, and the average adsorption energy of hydrogen molecules is 0.837 kcal/mol. The results show that it is possible to realize the hydrogen storage of sodium atoms decorated Si6 cage clusters in the normal temperature and atmospheric pressure.