Initially single H2 adsorption was modelled onto these Li decorated monolayers by placing one H2 at a distance of 2 Å from the bound Li atoms and allowing the systems to relax. These relaxed configurations can be seen in Fig. 15. H2molecules were seen to adsorb more strongly in these double-sided decorated systems with the highest average H2 binding energy seen in the Li decorated SV system of -0.388 eV/H2. In order to measure the gravimetric densities for the lithium decorated systems, equal number of H2molecules were placed in the vicinity of both the Li atoms and the systems were allowed to relax. It was seen that, the average H2 adsorption energies remained negative until 28 H2 molecules were adsorbed on both the substrates with the Li decorated SV silicene showing the highest gravimetric density of 5.97 wt% out of the two systems. The average distance between the Li atoms and the H2 molecules was measured in both cases and was found to be below 2.6 Å with the farthest H2molecule in each case being less than 2.8 Å away, indicating that all the H2 molecules were sufficiently adsorbed. The relaxed structures of the 28 H2 adsorbed Li decorated SV and SW silicene can be seen in Fig. 16.