Organic‐Acid‐Mediated Growth of Oriented Membrane from 2D‐Structured Zirconium MOF for CO ₂ Separation

Abstract

Abstract Two‐dimensional structured metal–organic framework (2D‐structured MOF) membranes with functionalized and ordered‐direction pores hold significant promise for efficient CO 2 separation. However, the direct synthesis of such membranes remains a substantial challenge. Herein, we report a novel organic‐acid‐mediated conversion strategy for direct transformation of a preformed metal–organic gel (MOG) into an oriented membrane of 2D‐structured MOF. The MOG is initially synthesized and subsequently dissociated to release Zr 6 clusters, which promotes the nucleation and growth of the MOF structure. Small organic molecules of formic acid are employed to modulate the coordination between Zr 6 clusters and 4,4′,4″‐tricarboxyltriphenylamine ligand (TCA 3− ). By finely tuning the balance between crystallization and intergrowth kinetics, a highly oriented Zr‐TCA membrane is fabricated, exhibiting excellent crystallinity and structural homogeneity. The resulting Zr‐TCA membrane features nitrogen‐functionalized, well‐aligned pores oriented parallel to the direction of gas permeation; enabling outstanding CO 2 /N 2 separation performance, with an exceptional CO 2 permeance of 1857.3 GPU and a high CO 2 /N 2 selectivity of 39.2 at 0.12 MPa and 25 °C.