Li adsorption on monolayer and bilayer MoS₂ as an ideal substrate for hydrogen storage

Based on the first-principles plane wave calculations, we show that Li adsorbed on monolayer and bilayer MoS₂ forming a uniform and stable coverage can serve as a high-capacity hydrogen storage medium, and Li-coated MoS₂ can be recycled by operations at room temperature due to Li having strength binding, big separation and is stable against clustering. The full Li coverage MoS₂ system (2*2 hexagonal MoS₂ supercell) can reach up to eight H₂ molecules on every side, corresponding to the gravimetric density of hydrogen storage up to 4.8 wt% and 2.5 wt% in monolayer and bilayer MoS₂, respectively. The adsorption energies of hydrogen molecules are in the range of 0.10eV/H₂-0.25 eV/H₂, which are acceptable for reversible H₂ adsorption/desorption near ambient temperature. In addition, compared with light metals decorated low dimension carbon-based materials, the sandwiched structure of MoS₂ exhibits the greatly enhanced binding stability of Li atoms as well as slightly decreased Li-Li interaction and thus avoids the problem of metal clustering. It is interesting to note that the Li atom apart from the electrostatic interaction, acts as a bridge of hybridization between the S atoms of MoS₂ and adsorbed H₂ molecules. The encouraging results show that such light metals decorated with MoS₂ have great potential in developing high performance hydrogen storage materials.