Research On Preparation And Properties Of Functionalized Mofs Nanocatalysts With Controllable Distribution Of Noble Metal Nanoparticles

Metal-organic frameworks?MOFs?materials have important research and application value in many fields due to their porosity,high specific surface area,multiple components and diverse structure.In recent years,increasing research attentions have been focused on building MOFs superstructures,such as hollow structures,membrane and three-dimensional architectures,at nanoscale.The combination of MOFs and functional nanoparticles?NPs?to form hybrid NPs/MOFs materials based on MOFs superstructures may greatly extend the applications of general MOFs due to their collective properties derived from the porosity of MOFs and the functionality of functional NPs.Metal-organic frameworks?MOFs?-supported noble metal nanoparticles?NMNPs?catalysts attract increasing attention due to their high durability and efficiency in catalytic reaction,which not only avoids the disadvantage of easy agglomeration of NMNPs,but the combination of the two can also achieve synergistic catalysis.In order to investigate the effect of the location-effect and loading amount of NMNPs inside MOFs on catalytic reaction of NMNPs-supported nanocatalysts,in this paper,we choose MIL-100?Fe?,which has a large pore size,high specific surface area,MOFs materials with abundant Lewis acid sites and excellent water and chemical as support to controllably load Pt NPs into MIL-100?Fe?by developing a simpler"Multiple growth method".Considering that the recycling rate of composite materials is not high in practical applications,magnetic Fe₃O₄microspheres were also selected as the deposition template of MIL-100?Fe?to facilitate the recycling of composite catalysts.The main research progress achieved is as follows:?1?Preparation of Fe₃O₄@MIL-100?Fe?series composite adsorbents—A multiple growth method was developed for controlling the loading percentage of MOFs in Fe₃O₄@MIL-100?Fe?series composite adsorbents,which also provide a simple and effective method for subsequent NMNPs?positioning packaging;Fe₃O₄@MIL-100?Fe?composite adsorbents with various MOFs loading percentage were obtained by decomposing different growth times of MIL-100?Fe?on Fe₃O₄microspheres;The methylene blue?MB?adsorption test on the Fe₃O₄@MIL-100?Fe?series composite adsorbents suggested that the dye adsorption capacity and adsorption efficiency were enhanced along with enhanced MOFs loading percentage in Fe₃O₄@MIL-100?Fe?series composite adsorbents.?2?Inserting single-layered Pt nanoparticles at the designated location inside MIL-100?Fe?for promoted catalytical performance—Single-layered Pt nanoparticles are inserted at the designated location inside MIL-100?Fe?through"Multiple growth method"to investigate the location-effect of NMNPs inside MOFs on catalytic reaction.Comparison test on the reduction of p-nitrophenol?p-NP?suggests that the location of the single-layered Pt nanoparticles inside MIL-100?Fe?largely influences the catalytic performance and the single-layered Pt nanoparticles inside MIL-100?Fe?locate closer to the outer surface of the MIL-100?Fe?providing higher catalytical efficiency.Possible reasons are concluded as that the location of the single-layered Pt nanoparticles inside MIL-100?Fe?dominates the reactants transport pathway and the loading amount of Pt nanoparticles.?3?Preparation of Fe₃O₄@MIL-100?Fe?-Pt series core-shell catalysts with multi-layer and controllable distribution of Pt NPs—The method of multiple growth was also used to quantitatively load single-layer,double-layer and three-layer Pt NPs in the process of MIL-100?Fe?deposition.The results of catalytic experiments showed that the higher the loading percentage of multi-layer Pt NPs with controllable distribution,the better the catalytic performance we got.