Oriented Exfoliating 3D Metal-Organic Frameworks into Ultrathin Metal-Organic Nanosheets with Different Crystal Faces

Manufacturing two-dimensional (2D) materials or nanosheets with desired crystal faces originating from an established intrinsic 3D structure is a significant challenge. Herein, an intrinsic t3D metal-organic frameworks (MOFs) can be exfoliated into ultrathin metal-organic nanosheets with (001) and (101) crystal faces, which is regulated by the solute's shard and soft acid-base and pH value in the exfoliating solution. The inorganic ligands (with different charges) possessing the similar hardness of Lewis acid-base of metal center can replace some of the organic ligands along the established crystal faces of the 3D MOFs with different electrostatic potentials, resulting in the exfoliating of the 3D MOFs into metal-organic nanosheets with different crystal faces. Using the Knoevenagel reaction as the catalytic reaction model, the catalytic activity of (001) crystal faces is three times that of (101) crystal faces, which is determined by the different locations of open metal sits in the 3D lamellar structure, further confirming the occurrence of oriented exfoliation. An intrinsic three-dimensional metal-organic framework can be exfoliated into metal-organic nanosheets exposed different crystal facets by the solute's hard and soft acid-base and charge of Lewis bases in exfoliating solution. The catalytic activity of (001) crystal faces is much higher than that of (101) crystal faces, attributed to more catalytic active sites expose on the former. image