二氧化钛基空心纳米光催化剂的合成、改性及光催化性能研究

发布时间：2018-05-28 01:27

  本文选题：TiO_2空球 + Au/TiO_2　； 参考：《浙江师范大学》2015年硕士论文

【摘要】：由于其优异且稳定的物理和化学性能,二氧化钛(TiO2)已在诸多领域中有了实际应用,如太阳能电池、光催化、光子晶体、气敏传感器、自清洁器件和生物医药等领域。就TiO2在光催领域的应用而言,其性能受晶相、禁带宽、颗粒尺寸、比表面积及结晶度等多个因素的影响,合成具有高结晶度、小尺寸、高比表面的锐钛矿TiO2纳米光催化剂将具有最佳的应用前景。同时,为了提高反应物在催化体系中的扩散,设计中空的催化剂结构也能显著提高催化剂的催化效率。本论文以制备高性能中空结构的TiO2为目标,设计了一种“沉积-自刻蚀-再沉积”的合成方法,成功地制备了一种镶嵌在SiO2薄层中的TiO2空球；在此基础上,我们通过对材料进行不同温度的水热处理,获得了不同壳层厚度的TiO2中空结构；同时,我们通过在TiO2空球内原位生长Au纳米颗粒,制备了一系列尺寸可控的具有yolk@shell结构的Au/TiO2空球。论文的具体内容主要分为以下三个方面：1)在微乳体系中,我们通过让有机硅烷和正硅酸乙酯同时水解,得到尺寸均匀的SiO2有机/无机小球模版。在该模板表面沉积TiO2时,TiO2的表面沉积可引发模板的自刻蚀,从而一步实现了TiO2空心纳米结构的制备。同时,少量被刻蚀的SiO2可再沉积到TiO2表面形成薄层。在SiO2薄层的保护下,TiO2空球可在900℃的高温下进行晶化,可获得锐钛矿相、小尺寸(5～8nm)、高结晶度的TiO2晶粒。同时,在退火过程中含氮有机硅烷中的氮元素可进入TiO2晶格内部,可形成氮掺杂TiO2,从而使得材料可对紫外光和可见光均能响应。我们通过TEM、SEM、XRD、XPS、FTIR spectrum、TGA等一系列手段对材料进行了表征。最后通过光催化降解染料(罗丹明B)证明材料具有优异的光催化性能。2)通过将1)中高温处理前的TiO2/SiO2复合空心纳米球作为前驱体,我们发现通过使用热水可刻蚀样品中的Si02成分,该过程可导致Ti02壳层小颗粒的重构,从而可得到一系列具有超薄结构的Ti02空心球。我们采用TEM、HTEM、 XRD、BET等手段对样品进行了分析,提出了样品“刻蚀-重构”的生长机理。通过光催化降解染料和光催化制备氢气等性能测试,我们分析了Ti02空球壳层厚度与其光催化性能之间的影响关系。3)通过在有机／无机SiO2小球模板中引入氨基硅烷,我们发现Ti02空球内可吸附大量氨基基团。利用氨基基团的还原性,我们在Ti02空球内部成功还原了氯金酸,从而可在空球内原位生长纳米金颗粒。通过对反应物浓度、反应时间、超声过程、加热条件及加热时间的细致优化,我们实现了单个金纳米颗粒在Ti02内的可控生长,并可选择性制备不同大小的金纳米颗粒。样品经过高温处理,可得到一系列具有yolk@shell结构的Au/TiO2中空核壳纳米颗粒。通过光解水实验测试材料性能,发现生长金纳米颗粒后材料催化制氢的能力显著增强,同时发现单位时间产氢的量和金颗粒的大小成正比关系。综上所述,我们制备了氮掺杂的TiO：空心纳米球和以其为前驱体的超薄壳层Ti02空球,及Au/TiO2的yolk@shell纳米材料,材料均表现出良好的光催化性能。这三种材料分别从拓宽太阳光响应范围、比表面和高效分离电子和空穴等三个方面提高了Ti02纳米材料的催化活性。上述基于Ti02空心纳米材料的研究有助于促进Ti02基纳米材料向实用方向的发展。
[Abstract]:Because of its excellent and stable physical and chemical properties, titanium dioxide (TiO2) has been applied in many fields, such as solar cells, photocatalysis, photonic crystals, gas sensors, self cleaning devices and biomedicine. The performance of TiO2 in the field of light is subject to crystal phase, forbidden bandwidth, particle size, specific surface area. The synthesis of anatase TiO2 nanoscale photocatalyst with high crystallinity, small size and high specific surface will have the best prospect of application. At the same time, in order to improve the diffusion of the reactant in the catalytic system, the design of the hollow catalyst structure can also improve the catalytic efficiency of the catalyst. A "deposition self etching redeposition" method was designed for the hollow structure of TiO2. A TiO2 hollow sphere embedded in a SiO2 thin layer was successfully prepared. On this basis, we obtained a TiO2 hollow structure with different shell thickness by heat treatment at different temperatures. In situ Au nanoparticles were grown in the TiO2 empty sphere, and a series of Au/TiO2 empty spheres with yolk@shell structure were prepared. The main contents of the paper were divided into three aspects: 1) in the microemulsion system, we obtained the homogeneous SiO2 organic / inorganic pellet template by hydrolyzing organosilane and tetraethyl orthosilicate at the same time. When TiO2 is deposited on the surface of the template, the surface deposition of TiO2 can lead to the self etching of the template, thus the preparation of the TiO2 hollow nanostructure is realized in one step. At the same time, a small amount of the etched SiO2 can be redeposited to the surface of the TiO2 to form a thin layer. Under the protection of the thin layer of SiO2, the TiO2 space ball can crystallize at 900 centigrade temperature, and the anatase phase can be obtained. The size (5 ~ 8nm), high crystallinity of TiO2 grain. At the same time, nitrogen in the nitrogen containing organo silane in the annealing process can enter the TiO2 lattice, and can form a nitrogen doped TiO2, so that the material can respond to both ultraviolet and visible light. We characterize the material through a series of means such as TEM, SEM, XRD, XPS, FTIR spectrum, TGA and so on. After photocatalytic degradation of dye (Luo Danming B), the material has excellent photocatalytic performance.2) by using TiO2/SiO2 composite hollow nanospheres as precursors before high temperature treatment in 1), we found that using hot water to etch Si02 components in the sample, this process can lead to the reconstruction of small particles of Ti02 shell, and thus a series of products can be obtained. Ti02 hollow spheres with ultrathin structures are analyzed by means of TEM, HTEM, XRD, BET and so on. The growth mechanism of the sample "etching reconfiguration" is put forward. The performance tests of the photocatalytic dye and photocatalytic preparation of hydrogen are put forward. The relationship between the thickness of the shell layer of Ti02 and the photocatalytic properties of the Ti02 is analyzed.3). Through the introduction of amino silane in the organic / inorganic SiO2 pellet template, we found that a large number of amino groups can be adsorbed in the Ti02 empty sphere. Using the reducibility of the amino group, we have successfully reduced chloric acid inside the Ti02 empty sphere, so that the nano gold particles can be grown in the empty sphere. With the careful optimization of thermal conditions and heating time, we have realized the controllable growth of single gold nanoparticles in Ti02, and can selectively prepare different sizes of gold nanoparticles. After high temperature treatment, a series of Au/TiO2 hollow core shell nanoparticles with yolk@shell structure can be obtained. The properties of the materials are tested by the photodissociation test. The capacity of catalytic hydrogen production by the present growth gold nanoparticles is significantly enhanced and the amount of hydrogen production per unit time is proportional to the size of the gold particles. In summary, we have prepared the nitrogen doped TiO: hollow nanospheres and the ultra-thin shell Ti02 hollow spheres with its precursors, and the yolk@shell nanomaterials of Au/TiO2. The three materials have improved the catalytic activity of Ti02 nanomaterials from three aspects, such as broadening the response range of the solar light, the surface and the high efficiency separation of electrons and holes, respectively. The research based on the Ti02 hollow nanomaterials can help to promote the development of the Ti02 based nanomaterials in the practical direction.
【学位授予单位】：浙江师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TB383.1

【共引文献】

相关期刊论文 前9条

1 曾爱香;罗丽;胡凯龙;;溶胶-凝胶法制备纳米TiO_2粉体的研究进展[J];材料导报;2013年19期

2 景茂祥;颜远瞻;平昱航;李立康;;介孔二氧化钛微球光催化剂的结构与性能[J];材料科学与工程学报;2014年01期

3 唐荣芝;王松林;张元卓;陈彤;王公应;;乙酸氧钛对碳酸二甲酯与苯酚酯交换的催化作用[J];高等学校化学学报;2014年11期

4 李海燕;龚丹;曾庆，

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