Ultrathin Metal–Organic\nFramework Nanosheets\nExhibiting Exceptional Catalytic Activity

Abstract

Two-dimensional\n(2D) metal–organic framework nanosheets\n(MONs) or membranes are classes of periodic, crystalline polymeric\nmaterials that may show unprecedented physicochemical properties due\nto their modular structures, high surface areas, and high aspect ratios.\nYet preparing 2D MONs from multiple components and two different types\nof polymerization reaction remains challenging and less explored.\nHere, we report the synthesis of MOF films via interfacial polymerization,\nwhich involves three active monomers for simultaneous polycondensation\nand polycoordination taking place in a confined interface. The well-defined\nlamellar structure of the MOF films allowed feasible and scalable\nexfoliation to produce free-standing 2D MONs with high aspect ratio\nup to 2000:1 and ultrathin thickness (∼1.7 nm). The pore structure\nwas revealed by high-resolution TEM images with near-atomic precision.\nThe imide-linkage of MONs provided superior thermal (up to 530 °C)\nand good chemical stability in the pH range from 3 to 12. More importantly,\nthe MONs exhibited exceptional catalytic activity and superior reusability\nfor the hydroboration reactions of alkynes, in which the turnover\nfrequency (TOF) reached 41734 h^–1, which is 2–4\norders of magnitude greater than that reported for homogeneous and\nheterogeneous catalysts.