Ultrahigh permeance metal coated porous graphene membranes with tunable gas selectivities

Membranes play an important role in gas separation on account of their low cost, energy efficiency, and durability. Gas-separation membranes, however, are subject to permeability-selectivity trade-off, i.e., atomically thin 2D materials such as porous graphene can provide ultrahigh permeances in the range of ∼105–107 GPU but suffer from low gas selectivity. Here, we show a new concept to enhance the selectivity of graphene-based membranes by employing adsorptive separation for binary gas mixtures. The deposition of “microislands” of Pd and Ni on the porous double-layer graphene support allowed us to selectively target H2 in He/H2 and CO2 in H2/CO2 mixtures, respectively, thus enabling efficient separation of He and also leading to the highest H2/CO2 separation factor of 26 within the ∼105 GPU permeance range. Moreover, the selective targeting of individual gases in a membrane setting through adsorptive separation at room temperature can be a promising alternative for economical gas separation