Room-Temperature Synthesis of Two-Dimensional Metal-Organic Frameworks with Controllable Size and Functionality for Enhanced CO2 Sorption

Two-dimensional (2D) metal-organic frameworks (MOFs), as a newly emerged member of 2D materials, have gained extensive attention due to their great potential in gas separation, sensing, and catalysis. However, it is still challenging to synthesize 2D MOFs with controllable size and functionalities using direct and scalable approaches at mild conditions (e.g., room temperature). Herein, we demonstrated one-step, room-temperature synthesis of a series of 2D MOFs based on Cu(II) paddle-wheel units, where the intrinsically anisotropic building blocks led to the anisotropic growth of 2D MOF nanoparticles, and the pillared structure led to high surface areas. The size of 2D MOFs can be adjusted by using a DMF/H2O mixed solvent. The thinnest particles were around 3 rim, and the highest aspect ratio was up to 200. The functionalization of 2D MOFs was also achieved by selecting ligands with desired functional groups. The gas sorption results revealed that amino and nitro-functionalized 2D MOFs showed higher CO, sorption selectivity over CH4 and N-2, suggesting these materials can be further applied in natural gas sweetening (CO2/CH4 separation) and carbon capture from flue gas (CO2/N-2 separation).