Seed-Mediated Synthesis of Gold Nanocrystals with Systematic Shape Evolution from Cubic to Rhombic Dodecahedral Structures

以植晶法合成具系統性形狀演化的金奈米粒子-由立方體演繹至菱形十二面體

吳欣倫(Hsin-Lun Wu)

指導教授 ： 黃暄益

國立清華大學/理學院/化學系/碩士(2009年)

https://doi.org/10.6843/NTHU.2009.00288

摘要

本篇論文是利用植晶法合成具系統性形狀演化的金奈米粒子，形狀變化可從立方體演繹到菱形十二面體。罕見的立方體、三角棱柱二十四面體及菱形十二面體在此可利用氯化十六烷基三甲基銨鹽做為保護劑、維生素C作為還原劑及加入少量的溴化鈉來合成，過渡形態的金奈米粒子亦可以同樣的方法合成。所有加入25微升晶種溶液的金奈米粒子，皆具有單一分布的形狀及大小，其大小約75奈米。而形狀演化是利用加入不同量的維生素C來達成，增加維生素C的量可使金奈米粒子的形狀從立方體轉變成三角棱柱二十四面體，最後變成菱形十二面體。
從結構鑑定證明立方體是由{100}的面所組成的，而菱形十二面體是由{110}的面所組成，我們成功地利用一個系統性的方法合成出全為{100}面及全為{110}面的金奈米粒子，並解釋這些形狀之間的關聯性。利用此合成方法亦可製備出截角立方體。這些新穎的金奈米粒子可用來檢驗其不同形狀及表面所產生的不同性質。
利用加入不同量的晶種溶液，我們成功地控制金奈米立方體及菱形十二面體的大小，加入晶種溶液的量越多，合成出的金奈米粒子就越小。當我們將加入的晶種溶液分別增加到45及65微升時，金奈米立方體及菱形十二面體的大小會減小到約55及40奈米。當加入晶種溶液的量增加到100微升時，金奈米立方體的大小甚至可以小到約30奈米。

關鍵字

金

並列摘要

We report the synthesis of gold nanocrystals with a systematic shape evolution from cubic to rhombic dodecahedral structures by a seeding growth approach. Unusual cubic, trisoctahedral, and rhombic dodecahedral structures can be synthesized by using cetyltrimethylammonium chloride (CTAC) surfactant as capping agent and ascorbic acid as reducing agent in the presence of NaBr. The transitional products can also be prepared. By adding 25 μL of the seed solution, particles with a monodispersed size of around 75 nm were synthesized. The shape evolution can be achieved by adding different amounts of ascorbic acid. By increasing the amount of ascorbic acid, the gold nanocrystals formed can be transformed from cubes to trisoctahedra, and then to rhombic dodecahedra.
Structural characterization confirmed that the cubes are bounded by {100} facets, whereas the rhombic dodecahedra are bounded by {110} facets. We have successfully used a systematic method to synthesize gold nanocrystals with entirely {100} or {110} facets and found the relationships among these shapes. Truncated cubes can also be synthesized by using this growth approach. These nanocrystals should allow the examination of their various properties as a function of particle shapes and surfaces.
By introducing different quantities of the seed solution, we were able to successfully control the size of the cubic and rhombic dodecahedral gold nanocrystals. The more seed solution was added, the smaller the particle size is. As the amount of the seed solution was increased to 45 and 65 μL, the gold cubes and rhombic dodecahedra showed smaller sizes of around 55 and 40 nm. The gold nanocubes can get even smaller to a size of approximately 30 nm by adding 100 μL of the seed solution.

並列關鍵字

gold

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