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

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.