Differential charge diagrams were also plotted and are shown in Fig. 10. The yellow regions between the Li and H2 showing electron depletion and blue regions near H2 showing electron accumulation confirm that there is electronic charge transfer between the two species. It can be inferred that the electronic charge transfer with H2 is primarily limited to just the lithium atom. This is primarily due to the cationic nature of the Li atom. The side view of the charge diagrams in the Li decorated SV silicene system shows that the electron accumulation and electron depletion regions surrounding both the H atoms in the H2molecule are symmetric in nature while Li decorated SW silicene shows slightly asymmetric regions. The electron accumulation regions at the Li-Si bonds indicate that charge is transferred from the substrate to the Li atom thus playing an indirect role in hydrogen adsorption. Similar charge distribution was also observed in the case of H2 adsorption onto Li decorated SW silicene with an indirect contribution towards hydrogen storage coming from the defected silicene substrate as well.
Fig 10. Charge Density diagram of a) H2 absorbed Li decorated SV Silicene and b) H2 absorbed Li decorated SW Silicene. Yellow regions and blue regions are representative of electron depletion and electron accumulation respectively. The isosurface level has been set as 0.00015000 e/Å3.