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首页> 外文学位 >Silver/titanium dioxide nanocomposites: Synthesis, characterizations and applications.
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Silver/titanium dioxide nanocomposites: Synthesis, characterizations and applications.

机译：银/二氧化钛纳米复合材料：合成，表征和应用。

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摘要

Nanosized noble metal (Au, Pt, Pd and Ag, etc.) particles are drawing increasing attention recently due to their widely spanned applications especially in catalytic reaction processes. Because of the much lower cost of silver than the other noble metals, development of high-performance silver-based nanomaterials is therefore of great significance. Small particle size and good dispersion of silver are the two key parameters determining its performances. To achieve these two features, deposition of silver onto less expensive supporting materials such as metal oxides has been generally practiced. Yet the major challenge is to achieve both high metal loading and good dispersion over the support surface simultaneously.;A novel one-pot sol-gel synthesis method was invented in the present study to produce TiO2-supported Ag nanoparticles with excellent Ag size and dispersion control while maintaining a high Ag loading. The adopted room-temperature ionic liquids in the precursor solution inhibited the Ag particle growth, as revealed by UV/visible spectroscopy results. X-ray Photoelectron Spectrometry (XPS) investigations reveal that silver exist predominantly in the metallic state in the products. The TiO2-supported Ag nanoparticles exhibit excellent catalytic activities towards the aqueous phase reductions of methylene blue and 4-nitrophenol, which can compete with more expensive Pt, Au and Pd nanocatalysts of similar size. Potent antibacterial activity against Escherichia coli was also observed in the Ag/TiO 2 nanoparticles, resulting from the small particle size and the high dispersion of silver over the TiO2 support. The Ag particles can also induce the deposition of Au, Pd and Pt on TiO2 surface via the galvanic replacement reaction scheme, which opens the possibility to synthesize other supported noble metal nanoparticles. The photocatalytic activities of TiO2 are enhanced by the Ag particles for the reduction of methyl viologen.
机译：近年来，由于纳米级贵金属（Au，Pt，Pd和Ag等）颗粒的广泛应用，特别是在催化反应过程中，它们引起了越来越多的关注。由于银的成本比其他贵金属低得多，因此开发高性能的银基纳米材料具有重要意义。小粒径和良好的银分散性是决定其性能的两个关键参数。为了实现这两个特征，通常已经实践了将银沉积到较便宜的支撑材料例如金属氧化物上。然而，主要的挑战是要同时实现高的金属负载量和在载体表面上的良好分散性。；本研究发明了一种新颖的单锅溶胶-凝胶合成方法，以生产具有优异的Ag尺寸和分散性的TiO2负载的Ag纳米颗粒控制，同时保持高的银负载量。如紫外/可见光谱结果所示，前体溶液中采用的室温离子液体抑制了Ag颗粒的生长。 X射线光电子能谱（XPS）研究表明，产品中的银主要以金属状态存在。 TiO2负载的Ag纳米颗粒对亚甲基蓝和4-硝基苯酚的水相还原具有极好的催化活性，可与更昂贵的类似尺寸的Pt，Au和Pd纳米催化剂竞争。在Ag / TiO 2纳米颗粒中也观察到了对大肠杆菌的有效抗菌活性，这是由于粒径小和银在TiO2载体上的高度分散所致。银颗粒还可以通过电流置换反应方案诱导TiO2表面上的Au，Pd和Pt沉积，这为合成其他负载型贵金属纳米颗粒提供了可能。 Ag颗粒增强了TiO 2的光催化活性，从而还原了甲基紫精。

著录项

  • 作者

    Zhang, Huanjun.;

  • 作者单位

    Hong Kong University of Science and Technology (Hong Kong).;

  • 授予单位 Hong Kong University of Science and Technology (Hong Kong).;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 199 p.
  • 总页数 199
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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