Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan.
Langmuir. 2013 Aug 20;29(33):10491-7. doi: 10.1021/la400985n. Epub 2013 Aug 7.
This study reports a systematic approach to synthesize ultralong gold nanorods and nanowires using a seed-mediated growth approach. In the first series, the effect of growth solution pH on the lengths of nanorods prepared was investigated. Interestingly, although shorter rods (230-310 nm) were produced in a basic solution environment than in an acidic condition (330-410 nm), the nanorod yield is greatly improved with relatively few nanoplate byproducts formed. Nanorod growth proceeds quickly in a basic solution as evidenced by the fast solution color changes. By adjusting several experimental parameters with the aim to elongate the nanorod length in a tunable fashion, gold nanorods and nanowires with average lengths from 580 to 2850 nm can be synthesized by progressively increasing the HNO3 concentration in the final growth solution. Nanowire growth in a highly acidic solution is slower, and a substantially longer time is needed to reach long lengths. Further extension of the nanowire length can be achieved simply by reducing the volume of second growth solution transferred to the final growth solution. Nanorods and nanowires with lengths spanning from 700 nm to 4.5 μm were prepared in this series of experimental conditions. The longest nanowires can reach a length of up to 6 μm. The nanowires still maintain thin average diameters of 33-53 nm. The ability to make gold nanorods and nanowires over this exceptionally wide and useful length range is exciting because applications and demonstrations using ultralong gold nanorods and nanowires of most suitable lengths are now possible.
本研究报告了一种使用种子介导生长方法合成超长金纳米棒和纳米线的系统方法。在第一个系列中，研究了生长溶液 pH 值对制备的纳米棒长度的影响。有趣的是，尽管在碱性溶液环境中制备的纳米棒较短（230-310nm），而在酸性条件下（330-410nm）较长，但纳米棒的产率大大提高，形成的纳米板副产物相对较少。碱性溶液中纳米棒的生长速度很快，这可以从溶液颜色的快速变化中得到证明。通过调整几个实验参数，以可调节的方式延长纳米棒的长度，最终可以合成平均长度从 580nm 到 2850nm 的金纳米棒和纳米线，通过逐步增加最终生长溶液中的 HNO3 浓度。在高度酸性的溶液中，纳米线的生长较慢，需要更长的时间才能达到较长的长度。通过减少转移到最终生长溶液中的第二生长溶液的体积，可以进一步延长纳米线的长度。在这一系列实验条件下，可以制备长度从 700nm 到 4.5μm 的纳米棒和纳米线。最长的纳米线可以达到 6μm 的长度。纳米线仍保持 33-53nm 的细平均直径。能够制造出具有如此宽和有用的长度范围的金纳米棒和纳米线是令人兴奋的，因为现在可以使用最合适长度的超长金纳米棒和纳米线进行应用和演示。
