Graphene with line defect as a membrane for gas separation: Design via a first-principles modeling

► The line defect consisting of octagons and pentagons presents poor separation capability. ► The new line defect composed of octagons and pores shows metallic property. ► The all-hydrogen passivated pore produces appropriate diffusion barriers for gases. ► The diffusion barrier derives from the electron overlap between molecule and pore. ► The new porous graphene presents high selectivity in favor of H2.