Ion-gated carbon molecular sieve gas separation membranes

Tailoring the Pore Size and Chemistry of Ionic Ultramicroporous Polymers for Trace Sulfur Dioxide Capture with High Capacity and Selectivity

Here we demonstrate the deep removal of SO₂ with high uptake capacity (1.55 mmol g^-1 ) and record SO₂ /CO₂ selectivity (>5000) at ultra-low pressure of 0.002 bar, using ionic ultramicroporous polymers (IUPs) with high density of basic anions. The successful construction of uniform ultramicropores via polymerizing ionic monomers into IUPs enables the fully exploitation of the selective anionic sites. Notably, the aperture size and surface chemistry of IUPs can be finely tuned by adjusting the branched structure of ionic monomers, which play critical roles in excluding CH₄ and N₂ , as well as reducing the coadsorption of CO₂ . The swelling property of IUPs with adsorption of SO₂ contributed to the high SO₂ uptake capacity and high separation selectivity. Systematic investigations including static gas adsorption, dynamic breakthrough experiments, stability tests and modeling studies confirmed the efficient performance of IUPs for trace SO₂ capture.

Broadening the Gas Separation Utility of Monolayer Nanoporous Graphene Membranes by an Ionic Liquid Gating

Ultrathin two-dimensional (2D) monolayer atomic crystal materials offer great potential for extending the field of novel separation technology due to their infinitesimal thickness and mechanical strength. One difficult and ongoing challenge is to perforate the 2D monolayer material with subnanometer pores with atomic precision for sieving similarly sized molecules. Here, we demonstrate the exceptional separation performance of ionic liquid (IL)/graphene hybrid membranes for challenging separation of CO₂ and N₂. Notably, the ultrathin ILs afford dynamic tuning of the size and chemical affinity of nanopores while preserving the high permeance of the monolayer nanoporous graphene membranes. The hybrid membrane yields a high CO₂ permeance of 4000 GPU and an outstanding CO₂/N₂ selectivity up to 32. This rational hybrid design provides a universal direction for broadening gas separation capability of atomically thin nanoporous membranes.