Synthesis And Catalytic Study Of Functionalized Covalent Organic Frameworks Composites

As an emerging class of porous crystalline materials,covalent organic frameworks(COFs)are synthesized by organic building blocks via strong covalent bonds.COF materials have attracted immense attention on account of their unique properties(e.g.high surface areas,uniform pore sizes,tailorable surface chemistry,and high thermal stability)and potential applications in gas storage,photoelectricity,energy conversion,drug delivery,proton conduction,and catalytic supports.COFs materials have great value in catalytic field.On the one hand,some specific functional groups of COFs,which have catalytic activity in some reactions,can be used as catalytic active sites.However,due to the few types of organic functional groups with catalytic activity,as active materials,COFs has been greatly restricted in catalysis;on the other hand,in order to enhance the functionality of COFs materials,which can be achieved by reasonably integrating them with other catalytic active materials(such as nanoparticles).As catalyst carriers,the application of COFs in catalytic field has been expanded..With the deepening of the research on COFs composite catalysts,how to effectively combine COFs with active sites and effective utilization of their pore characteristics has become the focus of study.(1)Au NPs/TPB-DMTP-COF materials were prepared by in-situ reduction method.First,we successfully synthesized monodisperse TPB-DMTP-COF microspheres,as a catalyst carrier,the microspheres were loaded Au NPs with different sizes by in-situ reduction method.As a model reaction,the microspheres were applied to the reduction of 4-nitrophenol and showed extremely high catalytic activity.(2)Different functional NPs@COF composites were prepared by a simple encapsulation method:In the process of COFs synthesis,functional nanoparticles were added as Cores,such as Fe3O4@COF,Fe2O3@COF and MIL-101@COF,and then COFs nucleated and grown to form different functional nanoparticles@COFs composites.(3)Fe3O4@COF-Au NPs catalysts were prepared by combination of encapsulation method and in-site reduction method:Herein,highly dispersed core-shell structured Fe3O4@COF NPs were constructed,and used as a support for the growth of ultrafine Au NPs(4.0 nm).The core-shell structured Fe3O4@COF-Au NPs exhibit remarkably catalytic activity for reduction reaction of 4-nitrophenol(4-NP)and methylene blue(MB)under mild conditions.Impressively,core-shell structured Fe3O4@COF-Au NPs with high stability can be easily recycled and reused in the reaction.More importantly,we further demonstrate that this synthesis method is a general technique to preparation Fe3O4@COF-PtNPs and Fe3O4@COF-Pd NPs.