Nanoporous MoS₂ monolayer as a promising membrane for purifying hydrogen and enriching methane

We present a theoretical prediction of a highly efficient membrane for hydrogen purification and natural gas upgrading, i.e. laminar MoS₂ material with triangular sulfur-edged nanopores. We calculated from first principles the diffusion barriers of H₂ and CO₂ across monolayer MoS₂ to be, respectively, 0.07 eV and 0.17 eV, which are low enough to warrant their great permeability. The permeance values for H₂ and CO₂ far exceed the industrially accepted standard. Meanwhile, such a porous MoS₂ membrane shows excellent selectivity in terms of H₂/CO, H₂/N₂, H₂/CH₄, and CO₂/CH₄ separation (>10³, >  10³, >  10⁶, and  >  10⁴, respectively) at room temperature. We expect that the findings in this work will expedite theoretical or experimental exploration on gas separation membranes based on transition metal dichalcogenides.