Design,Synthesis And Properties Of Metal-organic Framework Photocatalysts

Metal-organic frameworks（MOFs）are a class of crystalline porous materials by the self-assembly of some metal ions（clusters）and organic ligands.More attention and preference in potential applications on adsorption,catalysis,drug delivery,sensor and separation have been paid.The structural character of highly porosity and of the organic antenna linker simulating the metal nodes in MOFs make more researchers focus on MOF photocatalytic materials.Recently more and more photocatalysts based on MOFs were applied in the carbon dioxide reduction,hydrogen production,degradation of pollutants,and organic transformations.Herein,some metal sources such as manganese,cobalt and titanium salts react with several kinds of polycarboxylic ligands under the appropriate conditions,and several MOFs were prepared and characterized.The first chapter,some kinds of MOF-based photocatalytic materials were reviewed in details.This chapter listed several representative and recent application examples of MOFs materials as photocatalysts depends on the type of metal elements,ie,Zr,Ti,Fe,Zn,Co and Mn,and various strategies on optimizing their photocatalytic activity of MOFs are summarized.Finally the aim and scheme of this dissertation are given.The second chapter,the trinuclear manganese cluster as a precursor reacted with such some carboxylic ligands as terephthalic acid,1,3,5-benzenetricarboxylic acid and2,6-naphthalenedic acid respectively,as a result,three different crystalline MOFs as Mn-MOF-1,Mn-MOF-2 and Mn-MOF-3 were prepared and observed by UV-vis diffuse reflectance spectroscopy.UV-vis spectra revealed that the three compounds have strong and wide bands in the UV region and imply that those could be promising UV-light photocatalysts.The third chapter,three kinds of mixed-metal based MOFs as Co Ti-MOF-1,Co Mn-MOF-1 and Co Mn-MOF-2,were solvothermally prepared by one-pot method of mixed metal salts and linear dicarboxylic acid ligands.Their metal compositions of these MOFs were determined by EDX and XPS techniques.Thermogravimetric analysis showed that the three materials have great thermal stability in nitrogen atmosphere.Temperature-dependent magnetic susceptibility curves showed that Co Ti-MOF-1 and Co Mn-MOF-1 exhibit anti-ferromagnetism at higher temperatures.UV-vis spectra displayed strong absorption bands in the 200-800 nm regions with narrow level gaps,which confirm that those are very potential photocatalytic materials.The fourth chapter,a colorless massive crystal was obtained by using cerium sulfate as metal source in H₂O/DMF solvent system.Single crystal X-ray diffraction showed this compound is an unique cerium sulfate network in the template of formic acid,which called[Ce₂（HCOO）₂（SO₄）₂（H₂O）₂].In addition,the material exhibited antiferromagnetic interaction in the temperature range of 58-300 K.The fifth chapter,the structure and properties of the synthesized materials were summarized,and the potential applications of the coordination compounds in the field of photocatalysis were discussed.