Utilizing SO₂ as self-installing gate to regulate the separation properties of porous graphenes

We theoretically verify the reversible decoration of the pores of two-dimensional membranes to achieve tailorable separation. We show that SO₂ molecules can be used as “self-installing”doors to dynamically adjust the pore size of porous graphene sheets. For H atom-passivated porous graphene sheets (e.g. the pore16 model with pore size of 7.9 × 5.9 Å, small molecules such as H₂, CO₂, CH₄ can pass through freely), it can efficiently separate linear alkane molecules from their monobranched isomers (e.g. selectivity of 47500:1 for butane over isobutane). While after a SO₂ molecule is strongly adsorbed over pore16 as a partially closed gate, a mixture of smaller molecules like H₂/CH₄ can be separated successfully, with a selectivity of about 8100:1. The installed molecular gate can be uninstalled by heating, thus the porous membranes can be redecorated to meet the needs of other separation targets. This design principle can be extended to other porous membranes.