Fig 12. The variation in the potential energy and temperature of a H2 molecule adsorbed for a) Li decorated SV silicene and b) Li decorated SW silicene at 300 K.
To get a better understanding of the viability of these systems as hydrogen storage media, the defective silicene substrates were decorated with Li atoms both above and below the silicene monolayer and were allowed to relax. The relaxed configurations seen in Fig. 13. show that the two Li atoms bind to different Si atoms in the case of SW silicene. The upper Li atom binds to four Si atoms labelled 11, 12, 14 and 21 in Fig. 10 with the other Li atom binding to atoms 19, 21, 23 and 35. The two Li atoms in the SV silicene monolayer bind to three Si atom each. The average Li binding energies were found to be slightly lower in these double side decorated systems with the SV silicene system still showing higher binding energy of -3.14 eV/Li compared to that of SW silicene which was measured to be -2.57 eV/Li. It was observed that even upon decorating the Li atoms on both sides of the substrate, the average Li binding energy remained above the cohesive energy of Li. The average Si-Li bond lengths were found to be larger than the single side Li decorated systems measuring to be 2.76 Å and 2.60 Å for the SW silicene and SV silicene systems, which could relate to the slightly lesser binding energies in this case.