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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.