We report orientation-controlled synthesis of zirconium-based MOFs (Zr-MOFs) in which lowering DMF con
centration transforms 3D UiO-66 nanoparticles into 2D MIL-140A nanosheets (Zr-DMF50). Supported Zr-DMF50
membranes grown on a porous support exhibit continuous leaf-like morphology, maintain the MIL-140A phase,
and display molecular-sieving capability beyond Knudsen transport behavior. Furthermore, exfoliation of bulk
Zr-DMF50 powder yields high-aspect-ratio nanosheets that disperse stably in polar solvents and integrate uni
formly within a 6FDA-DAM polymer matrix. The resulting mixed matrix membranes (MMMs) show stronger
filler–polymer interactions and enhanced mechanical properties compared to those with 3D fillers. Remarkably,
a small loading (6 wt%) of 2D nanosheets achieves CO2 permeability comparable to 20 wt% 3D nanoparticles
while simultaneously enhancing CO2/N2 selectivity. These performance gains originate from increased diffu
sivity selectivity, whereas solubility selectivity remains unchanged. In addition, nanosheet-based MMMs exhibit
enhanced resistance to CO2 plasticization, with onset pressures of ~25 bar. These findings demonstrate that 2D
Zr-MOF nanosheets, synthesized through simple solvent concentration control, provide a promising route to
highly selective and stable membranes for post-combustion CO2 capture.