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Cu-TiO2复合零维/一维纳米材料的制备及其性能研究
赵鹏君
学位类型硕士
导师常爱民 ; 吴荣
2012-05-29
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业材料物理与化学
关键词Cu-tio2 异质结构 复合纳米管 可见光吸收 水热法
摘要纳米二氧化钛是一种极富前景的多功能材料,其成本低廉、物理化学性质优异,在光化学催化、染料敏化太阳能电池、锂离子电池等领域具有广泛的应用价值。但由 于其能隙较宽,光生载流子易复合等缺陷,限制了二氧化钛纳米材料的高效利用。目前常用的掺杂和贵金属复合等手段仅能片面地解决以上问题,无法最大限度地发 挥二氧化钛材料的优越性。 针对以上问题,本文首次采用一步水热合成法,利用金属铜代替贵金属与二氧化钛复合,成功制备了铜-二氧化钛零维异质纳米粒子、一维复合纳米管材料,并对这 两种材料的结构、物相组成、形成机制、理化性能等进行了探索性研究。 首先,本实验合成的一维Cu-TiO2复合纳米管材料,其物相组成为单质铜和锐钛矿。复合纳米管的长度约为100nm,二氧化钛纳米管直径为5-10 nm,其上负载的超微铜纳米粒子的尺寸约为5 nm。对于其反应过程的探究观察到不同寻常的反奥氏陈化现象,这一现象有助于合成粒径可控的量子尺寸纳米粒子。同时,非晶态的钛源和酸洗过程对最终产物的 物相组成和形貌具有很大的影响。本文还对该复合纳米管材料的光学吸收特性和可见光催化性能进行了研究。该材料在400-800nm的可见光区具有较强的吸 收,可见光催化实验表明,制得的复合纳米管材料在可见光辐照下有着较高的催化活性。 其次,本文还研究了一步法制备零维Cu-TiO2纳米粒子及其合成机理。该异质纳米粒子由单一立方相铜和锐钛矿相二氧化钛组成。高分辨透射电子显微镜 (HRTEM)在单一粒子中观测到清晰的铜(101)和二氧化钛(111)晶面构成的界面。同时,所制备纳米粒子的颗粒尺寸和光吸收特性可以通过改变 PEG分子链长进行微调。本文还对水热过程的反应机理进行了讨论,结果表明:PEG与铜氨络合物通过氢键连接,其链长对于粒子尺寸的影响在于PEG对Cu 颗粒的尺寸进行的调节,而此过程中二氧化钛的晶粒尺寸并无明显变化。紫外-可见吸收光谱表明该异质纳米粒子与普通二氧化钛纳米粉体相比,对可见光区光谱有 较为强烈的吸收。 本文所制备的两种复合纳米粒子均对可见光有这较强的吸收,使得此类材料有望应用于可见光催化降解有机物、染料敏化太阳能电池等领域。同时,本文一步法制备 复合纳米材料的核心在于金属离子与氨的络合,这使本方法有可能发展成为一种通用的金属-半导体复合纳米材料的通用简易制备工艺。
其他摘要Owing to their low cost, distinctive physical and chemical properties, The TiO2 materials on nanoscale have been widely used as multifunctional materials in many fields, such as the cathode of the lithium ions battery, photocatalyst, and the dye sensitized solar cells. However, its intrinsic defects, relatively wide energy band and recombination of electron-hole pairs, limit the applications of TiO2 to a large degree. Nevertheless, the current solutions such as doping and compositing with noble metals are one-sided in improving the performance of pure TiO2. Faced with such problems, the work presents a new one-step hydrothermal method to prepare the Cu-TiO2 1-D composite nanotubes and 0-D heterogeneous nanoparticles. And their architecture, phase composition and the formation mechanism are investigated in the paper. First, the obtained 1-D composite nanotubes are consisted of copper and anatase. Diameter and length of nanotubes are about 10-15 nm and 100-150nm, respectively. Dimension of the superfine nanoparticles is about 4-6 nm. Anti-Ostwald ripening, a decreasing of copper nanospheres’ dimension with the hydrothermal time, are observed from the TEM images, which is of benefit to control the particle size in quantum size. Meanwhile, the acid washing process and amorphous Ti precursor are essential for the successful formation of this unique topography and phase composition. UV-vis spectrum of the as-prepared material exhibits strong absorbance at 350-800 nm in the visible band compared with commercial TiO2 nanopowders. Photocatalytic experiment demonstrates the unique material has high photo catalytic activity under visible irradiation. Secondly, Cu-TiO2 heterostructure nanoparticles have been successfully synthesized via a novel one-step self-assemble hydrothermal method using polyethylene glycol as the soft template. Interfaces between Cu (101) and TiO2 (111) are observed from HRTEM. In addition, the nanoparticles size could be controlled by adjusting the polymerization degrees of PEG. The accommodations of the particle sizes were mainly caused by the Cu nanospheres rather than the TiO2. A possible synthetic mechanism interprets the formation of Cu-TiO2 heterogeneous nanoparticles could be ascribed to the hydrogen bonds between Cu(NH3)2+ and PEG. UV-vis absorption spectra indicates that the prepared product has strong absorbency in the visible region. Therefore, the two kind of unique interface nanomaterial could be used as a potential class of the materials platform as visible-light-driven photocatalyst and electrode on enhancing the photoelectric properties of solar cells. More significantly, the method may lead to a common process to prepare the metal-semiconductor composite 0-D and 1-D nanomaterials with controllable sizes and optical absorption properties.
文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/4378
专题材料物理与化学研究室
作者单位中国科学院新疆理化技术研究所
推荐引用方式
GB/T 7714
赵鹏君. Cu-TiO2复合零维/一维纳米材料的制备及其性能研究[D]. 北京. 中国科学院研究生院,2012.
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