Satoh Norifusa, Nakashima Toshio, Kamikura Kenta, Yamamoto Kimihisa
Department of Chemistry, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.
Nat Nanotechnol. 2008 Feb;3(2):106-11. doi: 10.1038/nnano.2008.2. Epub 2008 Feb 3.
The use of dendrimer templates to make metal-based nanoparticles of controlled size has attracted much interest. These highly branched macromolecules have well-defined structures that enable them to bind metal ions to generate precursors that can be converted into nanoparticles. We describe the sub-nanometre size control of both anatase and rutile forms of TiO2 particles with phenylazomethine dendrimers, leading to samples with very narrow size distributions. Such fine tuning is possible because both the number and location of metal ions can be precisely controlled in these templates. Quantum size effects are observed in the particles, and the energy gap between the conduction and valence bands exhibits a blueshift with decreasing particle size and is dependent on the crystal form of the material. The dependency of the bandgap energy on these factors is explained using a semi-empirical effective mass approximation.
使用树枝状大分子模板制备尺寸可控的金属基纳米颗粒引起了广泛关注。这些高度分支的大分子具有明确的结构，使其能够结合金属离子以生成可转化为纳米颗粒的前体。我们描述了用苯甲亚胺树枝状大分子对锐钛矿型和金红石型TiO₂颗粒进行亚纳米尺寸控制，从而得到尺寸分布非常窄的样品。这种精细调节是可能的，因为在这些模板中金属离子的数量和位置都可以精确控制。在颗粒中观察到了量子尺寸效应，导带和价带之间的能隙随着颗粒尺寸的减小而呈现蓝移，并且取决于材料的晶体形式。使用半经验有效质量近似来解释带隙能量对这些因素的依赖性。
