Graphdiyne confined-membrane with intrinsic in-plane-pores for angstrom-scale gas sieving.

Graphdiyne (GDY), an emerging carbon allotrope with inherent and well-defined in-plane nanopores, holds high potential as a molecular sieve membrane. However, experimentally validating its precision separation capability has been hindered by the challenges in fabricating continuous membranes with vertically accessible intraplane pores. Here, we develop a confinement-driven pore-registered synthesis strategy that enables the templated growth of GDY within the aligned meso-channels of covalent organic framework (COF), producing confined GDY nanomembranes. The resulting GDY⊕COF membrane exhibits high selectivity for separating 3-Angstrom gas molecules (H2, He) from larger molecules. Theoretical calculations reveal the selectivity originates from a synergy of strict size exclusion and an amplified electronic polarization effect within the unique GDY framework. As GDY represents an extensive family of graphyne materials with tuneable pore size and functions, this work not only addresses the challenge of small gas separation in graphitic membranes but also establishes a versatile strategy for developing advanced graphyne-family materials separation membranes.