一维二氧化钛的制备及Ag、Au纳米颗粒对其表面修饰

发布时间：2018-01-09 08:35

  本文关键词：一维二氧化钛的制备及Ag、Au纳米颗粒对其表面修饰　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 一维TiO_2纳米材料 不同形貌 表面光伏特性 表面改性

【摘要】：纳米TiO2是一种多功能半导体材料,因其具备强稳定性,无毒,电子迁移率高等优异特性,激起了研究者对其关注热潮。目前的研究结果表明TiO2在光催化、光电转换和紫外探测等领域均有广阔的应用前景。与其他TiO2粉体相比,一维纳米材料的稳定性更高,电荷传输能力更强,比表面积更大,这有利于提高其光电性能。同时,纳米材料的应用也依赖于不同形貌所表现出来的特点。目前报道了许多用湿化学法制备TiO2的研究成果,但是由于金属Ti的高熔点、低气压特性,很难在温和条件下采用气相法合成一维TiO2纳米材料。本文采用一种经济、简单的方法合成形貌各异的高结晶度一维TiO2纳米结构,讨论了不同形貌结构的生长机理和光电性能,并对TiO2纳米线的表面改性做初步研究,具体结果如下： (1)以Ti片为钛源,Pd为催化剂,采用CVD法,在不同催化剂含量和反应温度下,制备出形貌各异的TiO2纳米结构。实验发现,①Ti片在PdCl2：乙醇溶液中用紫外光照射30min、1h和2h,于900℃反应,得到的纳米线尺寸从56.4nm增至187.95nm,长度从几十微米减至几微米。②保持催化剂浓度一定,反应温度为700℃、730℃和800℃,分别得到了TiO2纳米片、纳米带和塔状结构。XRD和拉曼光谱表征证实所有的Ti02纳米结构都是纯净的金红石型；纳米线的形成为VLS生长机制,而纳米片、纳米带和塔状结构则是VLS和VS共同作用的结果。 (2)催化剂处理1h,在760℃下反应40min制备了带锯齿的锥状TiO2纳米带。锯齿的出现是纳米带在生长过程中,表面裸露的Ti+和O-的活性不同而引起生长速度不同形成的。单根纳米带的微区拉曼成像表明这种TiO2锥状结构的化学组分分布均匀,表面光伏测试中也表现了良好的光电响应,这对TiO2在光电器件方面的应用具有重要价值。 (3)最后采用光化学沉积法和浸渍-沉积法分别合成Ag/TiO2和Au/TiO2复合结构。比较了沉积不同时间的金属颗粒沉积量,沉积时间越长,吸附于TiO2纳米线表面的颗粒越多。当Au颗粒吸附时间为12h时,其拉曼光谱在441cm-1处发生了蓝移,这是由于过量的Au颗粒沉积在纳米线表面,挤压到TiO2的表面原子,使TiO2表面原子的相互作用力状态发生了变化。表面光伏曲线表明吸附适量金属颗粒的TiO2纳米线的光吸收范围有所拓宽,响应强度增强,说明金属颗粒的表面修饰有利于提高其光电性能。
[Abstract]:Nano TiO2 is a kind of multifunctional semiconductor material, because of its strong stability, non-toxic, high electron mobility and excellent characteristics, aroused the researchers attention to the boom. The results indicated that the TiO2 in photocatalytic field has broad application prospects of photoelectric conversion and UV detection. Compared with other TiO2 powder body, stability of one-dimensional nano materials is higher, the charge transfer ability is stronger, bigger than the surface area, which is conducive to improve the photoelectric performance. At the same time, the application of nano materials is also dependent on the characteristics of different morphologies is shown. At present, many research results reported by the wet chemical synthesis of TiO2, but due to the high melting point metal Ti, low pressure characteristics, it is difficult to use the gas phase synthesis of one-dimensional TiO2 nanomaterials under mild conditions. This paper uses a simple method for the synthesis of economy, different morphologies of high crystallinity of one-dimensional TiO2 nanostructures, The growth mechanism and photoelectric properties of different morphologies are discussed, and the surface modification of TiO2 nanowires is preliminarily studied. The results are as follows:
(1) to Ti as titanium source, Pd as catalyst, using CVD method in different catalyst concentration and reaction temperature, the fabrication of TiO2 nanostructures with various morphologies. The experimental results revealed that the Ti film on the PdCl2: 30min ethanol solution with UV irradiation, 1H and 2H to 900 DEG C, get the nanowire size increased from 56.4nm to 187.95nm, the length from tens of microns to several micrometers. The catalyst keep a certain concentration, the reaction temperature is 700 degrees, 730 degrees and 800 degrees, respectively, obtained TiO2 nanosheet, nanobelts and tower structure of.XRD and Raman spectra confirmed that the Ti02 nanostructures are all rutile pure; nanowire formation for VLS growth mechanism, and nanosheets, nanobelts and tower structure is the interaction of VLS and VS.
(2) catalyst 1H at 760 DEG C, reaction 40min prepared TiO2 nano cone toothed belt. Jagged is nanobelts in the growth process, the exposed surface of the Ti+ and O- activity caused by the different growth rate of different formation. With single nanometer micro Raman imaging surface chemical group this TiO2 cone structure points distribution, surface photovoltaic testing also showed good photoelectric response, has important value for the application of TiO2 in optoelectronic devices.
(3) the photochemical deposition and impregnation deposition method respectively to synthesize Ag/TiO2 and Au/TiO2 composite structure. The metal particle deposition amount of different deposition time, deposition time is longer, the more particles adsorbed on the surface of TiO2 nanowires of Au particles. When the adsorption time is 12h, the Raman spectra showed a blue shift in the 441cm-1, this is due to excessive deposition of Au particles in the nanowire surface, squeezed into the TiO2 surface atoms, the interaction state of TiO2 surface atoms changed. The surface photovoltaic curve showed that TiO2 nanowires adsorption amount of metal particles of light absorption range has widened, response intensity, description of surface modification of metal particles to improve the photoelectric performance.

【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.411

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