笼型Li6Si5团簇的结构和储氢性能研究

Structures and hydrogen storage properties of Li-decorated Si5 cage clusters

摘要:

利用密度泛函M06方法, 在6-311+G(d, p)基组水平上对Si5和Li修饰的Si5团簇的几何结构和电子性质及储氢性能进行理论计算研究. 结果表明, Si5团簇最低能量构型为笼型结构, 纯Si5团簇不能有效吸附氢分子. Li原子的引入显著改善了Si5团簇的储氢能力. 以六个Li原子穴位修饰Si5团簇为载体, 每个Li原子周围可以有效吸附三个氢分子, 其氢分子的平均吸附能为2.395 kcal/mol, 储氢密度可达16.617 wt%. 合适的吸附能和较高储氢密度表明Li修饰Si5团簇有望成为理想的储氢材料.

Abstract:

Based on the 6-311+G(d, p) set basis, the geometry structures, electronic properties and hydrogen storage properties of Si5 and LimSi5 clusters are investigated by using the density functional theory (DFT) M06 calculations. Our results indicate that the lowest energy structure of Si5 cluster is a three-dimensional cage, and it cannot efficiently store hydrogen molecules. It will remarkably improve the hydrogen storage capacity coated by Li atoms. The Si5 cage coated by six Li atoms (Li6Si5) can store up to 18 H2 molecules, in which every Li atom can efficiently adsorb three H2 molecules, corresponding to a maximum gravimetric density of 16.617 wt% with average adsorption energy of 2.395 kcal/mol per H2 molecule. The results demonstrate that Li decorated Si5 cage can serve as a promising hydrogen storage material at ambient conditions.