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The Preparation, Post-Functionalization and Properties of Metal-Organic Framework Films

Author: ZuoZhongShang
Tutor: QianGuoDong
School: Zhejiang University
Course: Materials Science
Keywords: metal-organic frameworks film gas separation post-functionalization luminescent sensing
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Type: PhD thesis
Year: 2014
Downloads: 12
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Abstract

As a new class of porous inorganic-organic hybrid crystalline materials, metal-organic frameworks (MOFs) which have unique chemical versatility, high surface areas and pores with tunable size and surface chemistry are exploring their applications in gas storage and separation, luminescence and sensing, etc. Films or membranes not only represent a low-cost, efficient and convenient way, but also extend the applications for the gases, such as membrane separation and gas sensing. However, the researches on the applications of films or membranes are still less, especially the continuous MOF membranes for the gas separation and the luminescent films for the gas sensing. In this thesis, the recent progress of MOF films or membranes is reviewed, with specific focus on the preparation methods of MOF films and applications of these materials. MOFs with pores functionalized with carboxylate acids were fabricated into continuous films on the porous anodic alumina oxide membranes and porous a alumina oxide plates using the in situ synthesis method, and CH4and N2gas separation properties of the MOF films between were studied. Continuous MOF films were prepared rapidly by in situ solvothermal synthesis method on silicon wafer modified with platinum nanoparticles. Luminescent films were achieved by the post-functionalization of the resulted MOF films with lanthanide ions and the in situ luminescent sensing of volatile thiols such as1,2-ethanedithiol and1-butanethiol was studied in detail. Three MOF films with different structures were prepared using the "two metal source" growth on the indium tin oxide (ITO) glass. Two kinds of MOF films with terbium-centered luminescence were achieved by the post-functionalization method. And the influence of energy transfer processes of the lanthanide-centered MOF films to in situ oxygen sensing properties was studied in detail.In3O(OH)(H2O)2[BTC]2(MIL-100(In), BTC=1,3,5-benzenetricarboxylate acid) having large pores with carboxylate acids on the pore surface was solvothermally synthesized. MIL-100(In) takes up CH4(9.95cm3/g) at298K and1atm, and this value is much higher than that of N2, which indicates that MIL-100(In) has the high adsorption selectivities of CH4with respect to N2. It is resulted from the carboxylate acids on the surface of the MOF pores which enhance the affinity between MOF and CH4intensely. Furthermore, continuous MIL-100(ln) films were prepared on the porous anodic alumina oxide membranes and porous a alumina oxide plates using the in situ synthesis method, and CH4and N2gas separation properties of the MOF films between were studied. It is shown that the MIL-100(In) film with the thickness of5μn on the porous anodic alumina oxide has the best gas separation properties and it has the biggest CH4/N2ideal selectivity of3.38with a CH4permeance of0.81×10-6mol·m-2·s-1·a-1. It is advised that the separation of CH4and N2is dominated by the surface diffusion mechanism and Knudsen diffusion mechanism together. The large pores endow the MOF films with high permeanbility while the carboxylate acids on the pore surface make sure the high gas separation selectivities. The results reveal that the functionalization of the pore surface can enhance the gas separation selectivities between some kinds of gases, this strategy provides a new design approach for MOF films.Continuous and well-grown MIL-100(In) films were prepared rapidly by in situ solvothermal synthesis method on silicon wafer modified with platinum nanoparticles. The heterogeneous nucleation and growth of MOF crystals on the platinum-coated Si wafer was improved by the platinum nanoparticles with high surface energy. Luminescent films, MIL-100(In)(?)Ln3+(Ln=Eu, Tb, Dy and Sm), were achieved by the post-functionalization of the resulted MOF films with lanthanide ions and the in situ luminescent sensing of volatile thiols such as1,2-ethanedithiol and1-butanethiol was investigated in detail. It is shown that the lanthanide ions are sensitized by organic linker via the metal carboxylates in the MOF pores. The luminescent quench percentages of the activated films reached ca.92%within120s for1,2-ethanedithiol and94%within20s, respectively. So the luminescent films show good performance in fast detection of volatile thiols which is toxic to human.Three indium trimesate MOF films with different structures, In12O(OH)12[(OH)4·(H2O)5][BTC]6(MIL-96(In)),[(CH3)2NH2][In3O(BTC)2(H2O)3]2[In3(BTC)4](CPM-5) and MIL-100(In), were prepared using the "two metal source" method on the indium tin oxide (ITO) glass. Sufficient nucleation precursor was formed on the surface by the reaction of trimesic acid and indium sources in the solution and on the ITO glass, which is similar to the Cu3(BTC)2film on the copper net. Two kinds of MOF films with terbium-centered luminescence, MIL-100(In)(?)Tb3+and CPM-5(?)Tb3+, were achieved by the post-functionalization method. The activated luminescent MOF films with high porosity exhibit fast and reversible detection of oxygen and the oxygen quenching of films under different oxygen partial pressure can be described by the linear Stern-Volmer relation. The Tb3+in MIL-100(In)(?)Tb3+is sensitized by the intramolecular energy transfer process while that in CPM-5(?)Tb3+is sensitized intermolecularly. The MIL-100(In)(?)Tb3+films shows higher oxygen sensitivity (the biggest Ksv≈14) and shorter response/recovery time (4s and39s) than those of CPM-5(?)Tb3+films.

The Preparation, Post-Functionalization and Properties of Metal-Organic Framework Films

Abstract

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