Preparation And Properties Of MOF Composite Functional Materials

Metal-organic frameworks(MOFs)are emerging polymer materials.They are formed by a transition metal ion or a metal ion cluster occupying a node and a bimodal or multimodal rigid organic linker in a coordination bond.For the material of such structure,access and transfer of some guest microcrystals can be allowed from the outside.One of the main advantages of MOF is that the diversity of transition metals can constitute a structurally diverse ligand.Another important feature of MOF is that it provides guest with a variety of chemical compositions great surface area and high porosity compare to other related microscopic and porous materials.Metal nanomaterials(MNPs)are structurally different from traditional materials due to their small size have excellent performance than traditional materials.However,due to the extremely small size of the MNPs,they have an very high specific surface energy,cause they rapidly oxidize or agglomerate in the air environment and the biological environment,exhibiting extremely poor stability which limits its application in various fields.The composite of MNPs with network or cage materials such as polymer and graphene can greatly improve MNPs stability in different environments.The 3D protective shell can effectively avoid self-agglomeration and oxidation of MNPs.By physically or chemically combining MNPs with MOF,the functional composites can be complemented by each other in performance,resulting in surprisingly synergistic synergistic effects,as they are fully superior to the original composite materials.Based on this idea,we conceived that MNPs were composited on a MOF material to prepare two functional materials,which were respectively used in catalytic hydrolysis of ammonia borane and lithium battery anode materials(1)CuNi NPs supported on MIL-101 as highly active catalysts for thehydrolysis of ammonia borane The catalysts containing Cu,Ni bi-metallic nanoparticles were successfully synthesized by in-situ reduction of Cu²⁺and Ni²⁺salts into the highly porous and hydrothermally stable metal-organic framework MIL-101 via a simple liquid impregnation method.When the total amount of loading metal is 3×10^-4mol,Cu₂Ni₁@MIL-101 catalyst shows higher catalytic activity comparing to Cu_xNi_y@MIL-101 with different molar ratio of Cu and Ni(x,y=0,0.5,1.5,2,2.5,3).Cu₂Ni₁@MIL-101 catalyst has the highest catalytic activity comparing to mono-metallic Cu and Ni counterparts and pure bi-metallic CuNi nanoparticles in hydrolytic dehydrogeneration of ammonia borane(AB)at room temperature.Additionally,in the hydrolysis reaction,the Cu₂Ni₁@MIL-101 catalyst possesses excellent catalytic performances,which exhibit highly catalytic activity and a very low activation energy value.The excellent catalytic activity has been successfully achieved attributed to the strong bi-metallic synergistic effects,uniform distribution of nanoparticles and the bi-functional effects between CuNi nanoparticles and the host of MIL-101.Moreover,the catalyst also displays satisfied durable stability after five cycles for the hydrolytically releasing H₂from AB.The nonnoble metal catalysts have broad prospects for commercial applications in the field of hydrogen-stored materials due to the low prices and excellent catalytic activity.(2)Co(BO₂)₂supported on MIL-101 as High-performance Anode Material for Li-ion BatteryIn this work,Co(BO₂)₂nanoparticles are successfully loaded on the surface of Cr-based metal organic frameworks MIL-101 without destroy the three-dimensional organic frameworks via a simple liquid impregnation method.As received Co(BO₂)₂@MIL-101composite shows the improved cyclability when serves as anode for rechargeable Li-ion batteries.The Co(BO₂)₂@MIL-101 electrode demonstrates high reversible capacity and stable cycle performance(coulombic efficiency remains above 95%)and a lower impedance than pure Co(BO₂)₂.The improvement could be attributed to that the MIL-101 provides effective barrier spaces for Co(BO₂)₂to relax the volumetric variation and maintain superior conductivity during the charge and discharge process.