Research On Preparation And Properties Of NMNPs@MIL-100(Fe) Composite Nanocatalyst

Metal organic frameworks(MOFs),a new class of crystalline microporous materials,are composed of metal ions and organic ligands linked by covalent bonds.MOFs have attracted extensive attention of chemical and material science researchers in the past 20years.MOFs have been widely used because of their unique topological structure,high porosity,high surface area,and adjustable and modified chemical composition.Based on these characteristics of MOFs,the composite materials formed by the combination of MOFs materials and Metal nanoparticles(MNPs)not only show the properties of composition,but also show new characteristics,such as selective catalysis,cascade catalysis,enhanced photocatalysis,cooperative detection,etc.Noble metal nanoparticles(NMNPs)are often used as catalysts for reaction due to their high surface energy and catalytic activity.However,due to their small size and thermodynamic instability,they tend to agglomerate during the reaction process,resulting in the loss of activity.In order to improve the catalytic performance of NMNPs load and MOFs materials,can not only avoid the reunited NMNPs shortcomings,the combination of the two often gain synergy,but type NMNPs MOFs compound on the synthesis methods of nanometer catalyst has a big challenge,generally speaking,there are two ways:the first is in the pore formation NMNPs MOFs,formed in this way NMNPs precursor prone to displacement or lost;The second method is to coat MOFs on the surface of NMNPs.In this method,the growth of MOFs is self-polymerizing,which presents great challenges in terms of synthesis conditions.To explore MOFs type and the thickness of MOFs for NMNPs MOFs composite nanometer catalyst performance,the influence of in this article,we use MIL-100(Fe)which has a large aperture,high specific surface area and lewis acid sites and water rich outstanding stability and chemical stability of MOFs materials as the carrier,adopt different strategies to achieve NMNPs load in MIL-100(Fe).The main research contents are as follows:(1)Preparation of Fe₃O₄@Pt@MIL-100(Fe)core-shell composite catalyst--A"one-pot"method was used to prepare the Fe₃O₄@Pt@MIL-100(Fe)core-shell composite catalyst,in which Pt nanoparticles(Pt NPs)were coated by Fe₃O₄ conversion to MIL-100(Fe).Fe₃O₄ not only acts as a magnetic core to improve the recovery of the catalyst,but also provides a continuous supply of Fe³⁺for the synthesis of MIL-100(Fe).The catalytic reduction experiments of nitrophenol showed that Pt NPs played a major catalytic role as catalyst,and MIL-100 played a synergistic catalytic role.(2)Preparation of Ag@MIL-100(Fe)core-sheath composite catalysts and catalytic reduction of nitrophenol--A series of Ag@MIL-100(Fe)composite catalysts with different content of MIL-100(Fe)were obtained by"multiple growth method"and different growth times of MIL-100(Fe)on the surface of Ag nanowires were controlled.Catalytic reduction experiments on nitrophenol showed that Ag nanowires played a major catalytic role as catalyst,and MIL-100(Fe)played a synergistic catalytic role.With the increase of MIL-100(Fe)content,the catalytic efficiency decreased,which was mainly attributed to the combined effect of MIL-100(Fe)on the adsorption of substrate and diffusion limitation.(3)Preparation of Ag@MIL-100(Fe)core-sheath series composite catalyst--A series of Ag@MIL-100(Fe)composite catalysts with different content of MIL-100(Fe)were obtained by"multiple growth method"and different growth times of MIL-100(Fe)on the surface of Ag nanowires were controlled.Experiments on the photocatalytic degradation of Methylene blue(MB)show that MIL-100(Fe)as a photocatalyst plays a major catalytic role,while Ag nanowires play a co-catalyst role,and the catalytic efficiency increases with the increase of the content of MIL-100(Fe).(4)Spherical Ag/AgCl@MIL-100(Fe)core-sheath in preparation of composite catalyst series-will Ag nanowires were soaked in Fe Cl₃·6H₂O and H₃btc solution,in this reaction,Fe³⁺silver oxide nanowires,and in the presence of Cl^-make it into the Ag/AgCl compounds,moreover because of the existence of solution of Fe³⁺and H₃btc can smooth surface coating on the surface of Ag/AgCl complex MIL-100(Fe)photocatalytic degradation of Methylene blue(Methylene MB)showed that the effective integration of Ag/AgCl with MIL-100(Fe)greatly improved the photoreactivity of MIL-100(Fe)under visible light.(5)Preparation of the rod Ag/AgCl@MIL-100(Fe)core-sheath series composite catalyst--AgCl nanoparticles were grown on the surface of Ag nanowires by slow etching method,and then coated with MIL-100(Fe)shell by multiple growth method for photocatalytic degradation of RhB.The results showed that Ag/AgCl was a good plasma,which significantly improved the photocatalytic degradation efficiency of MIL-100(Fe).(6)Preparation of Ag/MIL-100(Fe)@Gel composite hydrogels-The Ag/MIL-100(Fe)@Gel composite hydrogel was synthesized by free radical polymerization by mixing the photocatalyst material with the raw material of the hydrogel by physical mixing method.The experiment of photocatalytic degradation of MB showed that the efficiency of photocatalytic degradation increased with the increase of photocatalyst load at first,and then reached equilibrium.This is because as the amount of catalyst increases to a certain level,the amount of catalyst is no longer a limiting factor.In addition,the catalyst materials are mixed with hydrogels to facilitate recycling and catalyst collection.