金属有机框架（MOFs）材料的制备、表征及水氧化性能研究
发布时间：2018-11-13 07:14
【摘要】：MOFs是一种高孔隙率结构多样的结晶性材料,因其具有多孔性和热稳定性已成为具有发展潜力的催化材料。发展基于非贵金属的MOF材料,并将其应用于模拟光合系统II具有重要意义和应用价值。本论文总结了水氧化催化剂的研究进展和MOFs材料在催化领域的应用,制备并表征了三种MOF-Fe、一种MOF-Eu以及两种MOFs复合材料,研究了它们的催化水氧化性能以及对苯甲醇的催化氧化性能,最后探讨了这些MOFs材料的光催化机理。其主要研究内容及创新点如下:(1)通过静电自组装的方法合成了基于稀土金属铕的MOF/GO复合材料,通过扫描电镜(SEM)、X-射线衍射(XRD)、红外光谱以及拉曼光谱表征了其结构,并将其应用于不同条件下的光催化水氧化反应,研究了其催化机理。根据实验结果分析发现GO的复合有效地提高了电子迁移速率,减少了光生电子-空穴对的复合,增强了光催化活性。MIL-LIC-1(Eu)良好的可见光吸收性能使其成为集光敏剂与催化剂于一体的多功能多孔材料。捕获实验分析发现,光生空穴和·OH是催化过程中的活性中间体。在此基础上,我们检测了MIL-LIC-1(Eu)及其复合物在不同条件下对苯甲醇的氧化活性,并探讨了对苯甲醇的氧化机理。根据实验结果推测,水是催化过程中的重要氧源,在有水参加的醇氧化体系中,苯甲醇的转化率可达85.4%。此研究结果为以水为氧源的其它光驱动氧化反应提供了一种新思路;(2)制备了三种不同羧基配体的铁基MOFs材料(MIL-53(Fe)、NH_2-MIL-53(Fe)和MIL-100(Fe),其对应的有机配体分别为对苯二甲酸、2-氨基对苯二甲酸和均苯三甲酸),根据BET、循环伏安曲线、光电性能、活性中间体的捕获结果,讨论了配体对铁基MOFs材料催化水氧化活性的影响。其中,MIL-100(Fe)的表现出较高的催化活性,TON值达到了119.4,TOF为0.75 min-1。结果表明,有机配体的长度和大小以及配位羧酸的数量与催化活性有直接关系。有机配体的分子体积越大、长度越长,形成的MOFs材料孔径越大,同时也会产生较多的有效的活性位点,所以就会表现出更好的催化活性。因此,一种含有较多配位点、分子长度和大小适中的有机配体的设计和筛选有助于制备出一种高活性的MOFs催化材料;(3)在NH_2-MIL-53(Fe)的基础上通过后修饰的方法制备了一种新型的铁/钴双金属MOFs复合物(FBNC),通过SEM、XRD、红外光谱、拉曼光谱等表征其结构,检测了FBNC在不同催化条件下的水氧化活性。通过电化学方法研究了复合物中金属价态的变化以及光电转换性能。研究表明,金属钴的引入有效地提高了前驱体NH_2-MIL-53(Fe)的水氧化和光电转换性能。实验证明这种双金属复合物还是一种集光敏剂和电子受体于一体的多功能光催化剂,水氧化的最高TON值达到了110.5,苯甲醇氧化转化率可达91.1%。因此,这种多功能的铁钴双金属MOFs复合材料为光活性材料的设计和功能化修饰提供了新思路。
[Abstract]:MOFs is a kind of crystalline material with high porosity and diverse structure. Because of its porosity and thermal stability, MOFs has become a potential catalytic material. It is of great significance and value to develop MOF materials based on non-precious metals and apply them to simulate photosynthetic system II. In this paper, the research progress of water oxidation catalysts and the application of MOFs materials in the field of catalysis are summarized. Three kinds of MOF-Fe, one kind of MOF-Eu and two kinds of MOFs composites are prepared and characterized. Their catalytic water oxidation and catalytic oxidation of benzyl alcohol were studied. Finally, the photocatalytic mechanism of these MOFs materials was discussed. The main research contents and innovations are as follows: (1) MOF/GO composites based on rare earth metal europium were synthesized by electrostatic self-assembly. (SEM), X-ray diffraction (XRD),) was used for scanning electron microscopy (SEM). The structure was characterized by IR and Raman spectra, and was applied to the photocatalytic water oxidation under different conditions. The catalytic mechanism was studied. According to the analysis of the experimental results, it is found that the recombination of GO can effectively increase the electron transfer rate and reduce the recombination of photogenerated electron-hole pairs. The photocatalytic activity of MIL-LIC-1 (Eu) was enhanced, and MIL-LIC-1 (Eu) became a multifunctional porous material with Guang Min and catalyst. The trapping experiments show that photogenerated holes and OH are active intermediates in the catalytic process. On this basis, the oxidation activity of MIL-LIC-1 (Eu) and its complexes for benzyl alcohol under different conditions was determined, and the oxidation mechanism of p-benzyl alcohol was discussed. According to the experimental results, water is an important oxygen source in the catalytic process, and the conversion of benzyl alcohol can reach 85.4in the alcohol oxidation system with water. The results provide a new idea for other photo-driven oxidation reactions with water as the oxygen source. (2) three Fe-based MOFs materials with different carboxyl ligands (MIL-53 (Fe), NH_2-MIL-53 (Fe) and MIL-100 (Fe),) were prepared and their corresponding organic ligands were terephthalic acid. Based on the BET, cyclic voltammetry curves, photoelectric properties and capture results of active intermediates, the effects of ligand on the catalytic water oxidation activity of iron based MOFs materials were discussed. Among them, MIL-100 (Fe) showed high catalytic activity, and the TON value reached 119.4 min-1., which was 0.75 min-1.. The results showed that the length and size of organic ligands and the amount of coordination carboxylic acids were directly related to the catalytic activity. The larger the molecular volume and the longer the length of the organic ligands, the larger the pore size of the MOFs materials, and at the same time, the more effective active sites will be produced, so they will exhibit better catalytic activity. Therefore, the design and screening of organic ligands with more coordination sites and moderate molecular length and size are helpful to the preparation of a highly active MOFs catalytic material. (3) on the basis of NH_2-MIL-53 (Fe), a novel Fe / Co bimetallic MOFs complex (FBNC), was prepared by post-modification method. Its structure was characterized by SEM,XRD, IR and Raman spectra. The water oxidation activity of FBNC under different catalytic conditions was tested. The changes of valence state and photoelectric conversion of metal in the complex were studied by electrochemical method. The results show that the introduction of cobalt can effectively improve the water oxidation and photoelectric conversion of the precursor NH_2-MIL-53 (Fe). The experimental results show that the bimetallic complex is also a multifunctional photocatalyst with Guang Min and electron acceptor. The highest TON value of water oxidation is 110.5 and the conversion of benzyl alcohol oxidation can reach 91.1%. Therefore, this multifunctional Fe-Co bimetallic MOFs composite provides a new idea for the design and functionalization of photoactive materials.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33;O643.36
本文编号：2328388
[Abstract]:MOFs is a kind of crystalline material with high porosity and diverse structure. Because of its porosity and thermal stability, MOFs has become a potential catalytic material. It is of great significance and value to develop MOF materials based on non-precious metals and apply them to simulate photosynthetic system II. In this paper, the research progress of water oxidation catalysts and the application of MOFs materials in the field of catalysis are summarized. Three kinds of MOF-Fe, one kind of MOF-Eu and two kinds of MOFs composites are prepared and characterized. Their catalytic water oxidation and catalytic oxidation of benzyl alcohol were studied. Finally, the photocatalytic mechanism of these MOFs materials was discussed. The main research contents and innovations are as follows: (1) MOF/GO composites based on rare earth metal europium were synthesized by electrostatic self-assembly. (SEM), X-ray diffraction (XRD),) was used for scanning electron microscopy (SEM). The structure was characterized by IR and Raman spectra, and was applied to the photocatalytic water oxidation under different conditions. The catalytic mechanism was studied. According to the analysis of the experimental results, it is found that the recombination of GO can effectively increase the electron transfer rate and reduce the recombination of photogenerated electron-hole pairs. The photocatalytic activity of MIL-LIC-1 (Eu) was enhanced, and MIL-LIC-1 (Eu) became a multifunctional porous material with Guang Min and catalyst. The trapping experiments show that photogenerated holes and OH are active intermediates in the catalytic process. On this basis, the oxidation activity of MIL-LIC-1 (Eu) and its complexes for benzyl alcohol under different conditions was determined, and the oxidation mechanism of p-benzyl alcohol was discussed. According to the experimental results, water is an important oxygen source in the catalytic process, and the conversion of benzyl alcohol can reach 85.4in the alcohol oxidation system with water. The results provide a new idea for other photo-driven oxidation reactions with water as the oxygen source. (2) three Fe-based MOFs materials with different carboxyl ligands (MIL-53 (Fe), NH_2-MIL-53 (Fe) and MIL-100 (Fe),) were prepared and their corresponding organic ligands were terephthalic acid. Based on the BET, cyclic voltammetry curves, photoelectric properties and capture results of active intermediates, the effects of ligand on the catalytic water oxidation activity of iron based MOFs materials were discussed. Among them, MIL-100 (Fe) showed high catalytic activity, and the TON value reached 119.4 min-1., which was 0.75 min-1.. The results showed that the length and size of organic ligands and the amount of coordination carboxylic acids were directly related to the catalytic activity. The larger the molecular volume and the longer the length of the organic ligands, the larger the pore size of the MOFs materials, and at the same time, the more effective active sites will be produced, so they will exhibit better catalytic activity. Therefore, the design and screening of organic ligands with more coordination sites and moderate molecular length and size are helpful to the preparation of a highly active MOFs catalytic material. (3) on the basis of NH_2-MIL-53 (Fe), a novel Fe / Co bimetallic MOFs complex (FBNC), was prepared by post-modification method. Its structure was characterized by SEM,XRD, IR and Raman spectra. The water oxidation activity of FBNC under different catalytic conditions was tested. The changes of valence state and photoelectric conversion of metal in the complex were studied by electrochemical method. The results show that the introduction of cobalt can effectively improve the water oxidation and photoelectric conversion of the precursor NH_2-MIL-53 (Fe). The experimental results show that the bimetallic complex is also a multifunctional photocatalyst with Guang Min and electron acceptor. The highest TON value of water oxidation is 110.5 and the conversion of benzyl alcohol oxidation can reach 91.1%. Therefore, this multifunctional Fe-Co bimetallic MOFs composite provides a new idea for the design and functionalization of photoactive materials.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33;O643.36
【参考文献】
相关期刊论文 前1条
1 王佩东;薛娟娟;胡琴汉;曲玲玲;陈秋云;;吡咯甲酮基钴配合物:一种水氧化催化剂[J];无机化学学报;2014年04期
，本文编号：2328388
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