Department of Chemistry , Ball State University , Muncie , Indiana 47306 , United States.
Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , Bern CH-3012 , Switzerland.
Langmuir. 2018 Dec 18;34(50):15517-15525. doi: 10.1021/acs.langmuir.8b02623. Epub 2018 Dec 10.
Controlling the size of nanoscale entities is important because many properties of nanomaterials are directly related to the size of the particles. Gold nanoparticles represent classic materials and are of particular interest due to their potential application in a variety of fields. In this study, hexanethiol-capped gold nanoparticles are synthesized via the Brust-Schiffrin method. Synthesized nanoparticles were characterized by various analytical techniques such as transmission electron microscopy, scanning tunneling microscopy (STM), UV-visible absorption spectroscopy and electrochemical techniques. We have varied the molar ratio of gold to the protecting agent (hexanethiol) to discover the effect of gold-to-hexanethiol ligand ratio on the size of gold particles. The clear correlation between particle size and molar ratio is found that the averaged particle size decreases from 4.28 ± 0.83 to 1.54 ± 0.67 nm as the gold-to-ligand molar ratio changes from 1:1 to 1:9. In contrast to a recent report that thiolated gold nanoparticles are under spontaneous disintegration when they are assembled on a gold substrate, our STM experiments proved that these gold nanoparticles can form a stable monolayer or multiple layers on the platinum electrode without observing disintegration within 72 h. Therefore, our STM experiments demonstrate that the disintegration behavior of gold nanoparticles is related to the type of ligands and the nature of substrate materials. In electrochemical experiments, these gold nanoparticles displayed an electrochemical quantized charging effect, making these nanoparticles useful in the device applications such as electrochemical or biological sensors.
控制纳米级实体的大小很重要，因为纳米材料的许多性质都与颗粒的大小直接相关。金纳米粒子是经典材料，由于其在各种领域的潜在应用而特别受到关注。在本研究中，通过 Brust-Schiffrin 方法合成了十六硫醇封端的金纳米粒子。通过各种分析技术对合成的纳米粒子进行了表征，例如透射电子显微镜、扫描隧道显微镜（STM）、紫外-可见吸收光谱和电化学技术。我们改变了金与保护剂（十六硫醇）的摩尔比，以发现金与硫醇配体比对金粒子尺寸的影响。发现粒径与摩尔比之间存在明显的相关性，即当金与配体的摩尔比从 1:1 变为 1:9 时，平均粒径从 4.28 ± 0.83nm 减小到 1.54 ± 0.67nm。与最近的一份报告相反，该报告称当金纳米粒子在金基底上组装时会自发分解，我们的 STM 实验证明，这些金纳米粒子可以在铂电极上形成稳定的单层或多层，在 72 小时内没有观察到分解。因此，我们的 STM 实验表明，金纳米粒子的分解行为与配体的类型和基底材料的性质有关。在电化学实验中，这些金纳米粒子表现出电化学量子化充电效应，这使得这些纳米粒子在电化学或生物传感器等器件应用中很有用。
