The Role of Bromide Ions in Seeding Growth of Au Nanorods

被引:134
作者
Garg, Niti [1 ]
Scholl, Clark [1 ]
Mohanty, Ashok [1 ]
Jin, Rongchao [1 ]
机构
[1] Carnegie Mellon Univ, Dept Chem, Pittsburgh, PA 15213 USA
关键词
SHAPE-CONTROLLED SYNTHESIS; GOLD NANORODS; OPTICAL-PROPERTIES; ASPECT-RATIO; METAL NANOPARTICLES; NANOCRYSTALS; SURFACTANT; CHEMISTRY; BIPYRAMIDS; EXCITATION;
D O I
10.1021/la100446q
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
We report our findings on the important role of bromide ions in the seeding growth process of Au nanorods. The seed-mediated process constitutes a well-developed method for synthesizing gold nanorods in high yield, which is facilitated by a micelle-forming surfactant, cetyltrimethylammonium bromide (CTA-Br). Despite the tremendous work in recent years, the growth mechanism of Au nanorods has not been fully understood. Contrary to the widely accepted mechanism of CTA(+) micelle-templated growth of Au nanoroth, we have identified the critical role of bromide ions in the seeding growth of Au nanorods. We found that even when the micelle-forming agent (CTA(+) concentration is below its critical micelle concentration (cmc), bromide ions added in the form of NaBr can successfully effect the growth of Au nanorods in good yield. By controlling the concentration of externally added bromide ions, the rod shape and dimensions of the resulting Au nanoparticles can be readily controlled in the presence of only a minimum amount of CTABr (as a steric stabilizer for nanorods). High-resolution TEM studies show that the as-formed nanorods are perfectly single crystalline, instead of penta-twinned ones, and are bound by (Ill and {100} facets with a [110] direction as the elongation direction. A mechanism is proposed to account for the seeding growth of single crystalline Au nanorods. Overall, this work explicitly demonstrates that Br-(-) indeed serves as an important shape-directing agent for gold nanorod formation in the seed-mediated process.
引用
收藏
页码:10271 / 10276
页数:6
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