钛氧簇合物合成和光电性质的研究

发布时间：2018-05-28 05:17

本文选题：钛氧簇合物 + 晶体结构　；参考：《山东大学》2016年硕士论文

【摘要】：钛的氧化物如二氧化钛,是最重要的半导体材料之一,在光催化、光伏电池、光/电致变色、光子晶体、表面涂层以及传感器等方面具有非常重要的应用价值。钛氧簇合物是由多个钛原子通过桥氧连接而成的纳米尺寸的分子,是一种分子形式的钛氧化合物,在自下而上(bottom-up)策略构建有机-无机杂化纳米材料和太阳能的开发利用中具有潜在的应用。众所周知,溶胶凝胶法是合成过渡金属氧化物纳米材料的最基本和最重要的方法,而钛氧簇合物作为预成核(prenucleation)或者中间体存在于溶胶凝胶法合成二氧化钛的过程中,因此分离这些化合物对于理解二氧化钛形成的分子机制具有重要价值。本论文针对文献中广泛采用的二氧化钛纳米材料的可控合成方法,即卤化钛醇热法,通过控制反应时间,成功分离了一系列二氧化钛纳米晶生长的中间体,得到了多个结构新颖的和重要的钛氧簇合物,尤其是一个包含碘离子的22核笼状簇合物,并对这些化合物做了光电性质的研究。论文内容分为以下四个部分：第一部分,综述了金属氧簇合物的研究进展、种类及合成方法。总结了文献报道的钛氧簇合物的结构、性质及应用。重点介绍了二氧化钛纳米晶的成核和生长机制。最后,阐述了本论文选题的科学意义。第二部分,采用溶剂热方法合成了一个四核钛氧簇合物,[Ti_4O(O'Pr)_6(DTBC)_4],并对其光致电荷转移做了详细研究。该化合物可以看作3,5-二叔丁基邻苯二酚(DTBC)键合到TiO_2纳米颗粒表面的分子模型。DTBC通过螯合桥连模式键合到钛氧核的表面,苯环的π电子能够在光激发下直接跃迁到Ti3d轨道。对该簇合物的精确结构和电子转移机理的研究,有助于理解发色团在TiO_2表面的键合模式和染料敏化太阳能电池中的光致电子转移过程。第三部分,采用卤化钛醇热法,以TTIP和TiX_4(X= F、Cl、Br)作为前驱体,通过调节反应时间、温度、反应物比例等实验参数分离得到了三种卤素掺杂的钛氧簇合物。通过单晶X射线衍射解析了这些化合物的结构,并对其做了光谱表征和催化应用。第四部分,采用卤化钛醇热法,以TTIP和TiI_4作为前驱体,在不同的时间点分别得到了三个水解程度依次增大的中间体,其中最重要的是得到了一个包含碘离子的22核主客体笼状簇合物。对这些化合物的结构、组成、光谱性质和光电性质做了详细表征。采用后期修饰策略,成功将特戊酸和DTBC修饰到该笼状化合物表面,实现了表面功能化。以上化合物独特的结构、反应活性和光谱性质,使其成为主客体化学和光致电荷转移等研究的理想的分子模型。
[Abstract]:Titanium oxide, such as titanium dioxide, is one of the most important semiconductor materials. It has very important application value in photocatalysis, photovoltaic cell, photochromic / electrochromic, photonic crystal, surface coating and sensor. Titanium oxide clusters are nanometer-sized molecules connected by a plurality of titanium atoms through bridging oxygen. They are a kind of titanium oxide compounds in the form of molecules. It has potential applications in the development and utilization of organic-inorganic hybrid nanomaterials and solar energy. It is well known that sol-gel method is the most basic and important method for the synthesis of transition metal oxide nanomaterials, and titanium oxide clusters, as prenucleation or intermediates, exist in the process of synthesizing titanium dioxide by sol-gel method. Therefore, the separation of these compounds is of great value in understanding the molecular mechanism of titanium dioxide formation. In this paper, a series of intermediates of titanium dioxide nanocrystalline growth were successfully separated by controlling the reaction time for the controlled synthesis of titanium dioxide nanocrystalline materials, that is, the thermal method of titanium halide alcohol, which is widely used in the literature. A number of novel and important titanium oxide clusters, especially a 22-core cage cluster containing iodine ions, have been obtained, and their optical and electrical properties have been studied. The thesis is divided into four parts as follows: in the first part, the research progress, kinds and synthesis methods of oxygen clusters are reviewed. The structure, properties and applications of titanium oxide clusters reported in literature were summarized. The nucleation and growth mechanism of TIO _ 2 nanocrystalline were introduced. Finally, the scientific significance of this thesis is expounded. In the second part, a tetranuclear titanium oxide cluster, [Ti_4O(O'Pr)_6(DTBC)_4], was synthesized by solvothermal method and its photocharge transfer was studied in detail. This compound can be regarded as a molecular model of 3 ~ 5- di-tert-Ding Ji catechol (TDC) bonding to the surface of TiO_2 nanoparticles. The 蟺 electrons of benzene ring can be directly transferred to the Ti3d orbit by chelating bridging mode to the surface of the titanium oxide nucleus. The study of the exact structure and electron transfer mechanism of the cluster is helpful to understand the bonding mode of chromophore on the surface of TiO_2 and the photoelectron transfer process in dye sensitized solar cells. In the third part, three kinds of halogen-doped titanium oxide clusters were obtained by using TTIP and TiX _ (4) H _ (4) O _ (4) as precursors by adjusting reaction time, temperature, reactant ratio and other experimental parameters. The structures of these compounds were elucidated by single crystal X-ray diffraction, and their spectroscopic characterization and catalytic application were carried out. In the fourth part, using TTIP and TiI_4 as precursors, three intermediates with higher degree of hydrolysis were obtained at different time points by thermal method of titanium halides. The most important is to obtain a 22-core host-guest-cage cluster containing iodine ions. The structure, composition, spectral and optoelectronic properties of these compounds were characterized in detail. The latecomer modification strategy was used to modify the surface of the cage compound successfully, and the functionalization of the surface was realized. The unique structure, reaction activity and spectral properties of these compounds make them an ideal molecular model for the study of host-guest chemistry and photocharge transfer.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O641.4

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