Search

How defects between layers of porous membranes affect their gas separation performance is still a problem. Here, we design three bilayer porous graphene membranes with different and representative defect torsion angles to regulate gas separation. We find from first-principles density functional theory calculations that the selectivity of the H 2 /CH 4 mixture can be varied by several orders of magnitude, of about 107:1 (E barrier/CH4 : 0.24, 0.18, 0.24 eV), 1019:1 (E barrier/CH4 : 0.49, 0.37, 0.47 eV) and 1012:1 (E barrier/CH4 : 0.42, 0.15, 0.45 eV), when going through the models of bi-H pore10 -20 x , bi-H pore10 -20 y and bi-H pore10 -47 y. Every barrier curve of gas penetration features three peaks. Additionally, molecular dynamics simulations show that the bilayer porous graphene membrane with a defect torsion angle of 20° along the x / y -axis possesses high H 2 /CH 4 separation ratio (up to 56–58:1) at room temperature after 5000 ps. The defect torsion angle of bilayer porous graphene improves the selectivity exponentially by regulating the three high penetration energy barriers of CH 4 , while the three energy barriers of H 2 are all very low. This work provides a new strategy to achieve highly selective separation of mixture by porous 2D-materials via regulating defect torsion angle between layers. [Display omitted] • The defect torsion angle is a powerful knob for regulating gas separation. • The potential energy curve for defect torsion angle model features three peaks. • Bi-H pore10 -20 y shows a high separation selectivity of 1019:1 for H 2 over CH 4. [ABSTRACT FROM AUTHOR]