National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080, People's Republic of China. School of Physics and Materials Engineering, Dalian Minzu University, Dalian, 116600 People's Republic of China.
Nanotechnology. 2019 May 24;30(21):215601. doi: 10.1088/1361-6528/ab055b. Epub 2019 Feb 8.
For accurate experimental and theoretical research, the preparation of nanocrystrals with regular morphology is of significant importance. In this work, we investigated a facile and effective route for generating highly spherical Au@Ag nanospheres (NSs) with tuneable size and uniform morphology at room temperature. The aqueous synthesis mainly involved seed-mediated growth method together with oxidation etching employing sodium hypochlorite (NaClO) as etching agent. The termination of the etching reaction with NaClO as etching agent was simply related to the amount of NaClO and had no connection with time. Thus Au@Ag NSs with controllable diameters in range from 24 to 87 nm were prepared only by varying the amount of NaClO added into the solutions of Au@Ag nanocubes. Additionally, combined with interface self-assembly technique, Au@Ag NSs were assembled into densely arranged two-dimensional (2D) monolayer film. Moreover, the SERS performance of these monolayers were evaluated by calculating the analytical enhancement factor using crystal violet as probe molecule. The AEF increased obviously as the diameter of Au@Ag NSs went up, and the maximum AEF could reach to 0.94 × 10 at the laser excitation wavelength of 785 nm. Besides, the electromagnetic field distribution for Au@Ag NSs array were also confirmed by Mie theory and FDTD solutions software and the results revealed the similar trend with the experimental results. In general, this 2D assemblies in term of high quality Au@Ag NSs have broad prospects to act as promising candidates for SERS analytical sensor and other applications.
为了进行准确的实验和理论研究，制备具有规则形态的纳米晶体具有重要意义。在这项工作中，我们研究了一种在室温下生成具有可调尺寸和均匀形态的高球形 Au@Ag 纳米球（NSs）的简便有效方法。水相合成主要涉及种子介导生长法和使用次氯酸钠（NaClO）作为蚀刻剂的氧化蚀刻。NaClO 作为蚀刻剂的蚀刻反应终止与 NaClO 的用量有关，与时间无关。因此，通过改变添加到 Au@Ag 纳米立方体溶液中的 NaClO 的量，可以制备出直径在 24 至 87nm 范围内的具有可控直径的 Au@Ag NSs。此外，结合界面自组装技术，Au@Ag NSs 被组装成密集排列的二维（2D）单层膜。此外，通过使用结晶紫作为探针分子计算分析增强因子，评估了这些单层的 SERS 性能。随着 Au@Ag NSs 直径的增加，AEF 明显增加，在激光激发波长为 785nm 时，最大 AEF 可达 0.94×10。此外，还通过 Mie 理论和 FDTD 解算软件证实了 Au@Ag NSs 阵列的电磁场分布，结果与实验结果具有相似的趋势。总的来说，这种高质量 Au@Ag NSs 的 2D 组装具有作为 SERS 分析传感器和其他应用的有前途的候选物的广阔前景。
