Li原子修饰笼型Si_6团簇的结构和储氢性能

利用杂化密度泛函B3LYP方法,在6-311+G(d,p)基组水平上对Si_6和Li修饰的Si_6团簇的几何结构和电子性质及储氢性能进行模拟计算和理论研究.结果表明,Si_6团簇最低能量构型为笼型结构,纯Si_6团簇不能有效吸附氢分子.Li原子的引入显著改善了Si_6团簇的储氢能力.以两个Li原子端位修饰Si_6团簇为载体,其氢分子的平均吸附能为1.692~2.755 kcal/mol,每个Li原子周围可以有效吸附五个氢分子,储氢密度可达9.952 wt%.合适的吸附能和较高储氢密度表明Li修饰Si_6团簇有望成为理想的储氢材料.

Structures and hydrogen storage properties of Li-decorated Si6 cage clusters

Based on the 6-311+G(d, p) set basis, the geometry structures, electronic properties and hydrogen storage properties of Si6 and Li2Si6 clusters are investigated by using the hybrid density functional theory (DFT) B3LYP calculations. Our results indicate that the lowest energy structure of Si6 cluster is a three-dimensional cage, and it can not efficiently store hydrogen molecules for Si6 cage with the same method. It will remarkably improve the hydrogen storage capacity coated by Li atoms. The Si6 cage coated by two Li atoms (Li2Si6) can store up to 10 H2 molecules, in which every Li atom can efficiently adsorb five H2 molecules, corresponding to a maximum gravimetric density of 9.952wt% with an average adsorption energy of 1.692 kcal/mol per H2 molecule. The results demonstrate that Li decorated Si6 cage can serve as a promising hydrogen storage material at ambient conditions.