Department of Chemistry, University of Pennsylvania, Pennsylvania 19104, USA.
Nano Lett. 2013 May 8;13(5):2163-71. doi: 10.1021/nl400653s. Epub 2013 Apr 8.
We demonstrate for the first time that monodisperse gold nanorods (NRs) with broadly tunable dimensions and longitudinal surface plasmon resonances can be synthesized using a bromide-free surfactant mixture composed of alkyltrimethylammonium chloride and sodium oleate. It is found that uniform gold NRs can be obtained even with an iodide concentration approaching 100 μM in the growth solution. In contrast to conventional wisdom, our results provide conclusive evidence that neither bromide as the surfactant counterion nor a high concentration of bromide ions in the growth solution is essential for gold NR formation. Correlated electron microscopy study of three-dimensional structures of gold NRs reveals a previously unprecedented octagonal prismatic structure enclosed predominantly by high index {310} crystal planes. These findings should have profound implications for a comprehensive mechanistic understanding of seeded growth of anisotropic metal nanocrystals.
我们首次证明，使用由烷基三甲基氯化铵和油酸钠组成的无溴表面活性剂混合物，可以合成具有广泛可调尺寸和纵向表面等离子体共振的单分散金纳米棒（NRs）。研究发现，即使在生长溶液中碘离子浓度接近 100 μM 的情况下，仍能获得均匀的金 NR。与传统观念相反，我们的结果提供了确凿的证据，表明无论是作为表面活性剂反离子的溴化物，还是生长溶液中的高浓度溴化物离子，对于金 NR 的形成都不是必需的。对金 NR 三维结构的相关电子显微镜研究揭示了以前未曾见过的八角棱柱状结构，该结构主要由高指数 {310} 晶面封闭。这些发现对于全面理解各向异性金属纳米晶体的种子生长的机械机制具有深远的意义。
