Decarolis Donato, Odarchenko Yaroslav, Herbert Jennifer J, Qiu Chengwu, Longo Alessandro, Beale Andrew M
Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
Phys Chem Chem Phys. 2020 Sep 14;22(34):18824-18834. doi: 10.1039/c9cp03473k. Epub 2019 Sep 2.
The self-assembly of gold nanoparticles (Au NPs) using polymer-encapsulated inverse micelles was studied using a set of advanced X-ray techniques (i.e. XAFS, SAXS) in addition to DLS, UV-vis spectroscopy and TEM. Importantly the combination of these techniques with the inverse micelle approach affords us detailed insight and to rationalize the evolving molecular chemistry and how this drives the formation of the Au NPs. We observe that the mechanism comprises three key steps: an initial fast reduction of molecular Au(iii) species to molecular Au(i)Cl; the latter species are often very unstable during the self-assembly process. This is followed by a gradual reduction of these molecular Au(i) species and the formation of sub-nanometric Au clusters which coalesce into nanoparticles. It was also found that addition of small amounts of HCl can accelerate the formation of the Au clusters (the second phase) without affecting the final particle size or its particle size distribution. These findings would help us to understand the reaction mechanism of Au NP formation as well as providing insights into how NP properties could be further tailored for a wide range of practical applications.
除动态光散射（DLS）、紫外可见光谱和透射电子显微镜（TEM）外，还使用了一系列先进的X射线技术（即X射线吸收精细结构光谱（XAFS）、小角X射线散射（SAXS））研究了利用聚合物包裹的反胶束进行金纳米颗粒（Au NPs）的自组装。重要的是，这些技术与反胶束方法的结合使我们能够深入了解并合理解释不断演变的分子化学过程以及这一过程如何驱动Au NPs的形成。我们观察到该机制包括三个关键步骤：首先将分子态Au(iii)物种快速还原为分子态Au(i)Cl；后一种物种在自组装过程中通常非常不稳定。接下来是这些分子态Au(i)物种的逐步还原以及亚纳米级Au簇的形成，这些簇聚结形成纳米颗粒。还发现添加少量HCl可以加速Au簇（第二阶段）的形成，而不影响最终颗粒大小或其粒度分布。这些发现将有助于我们理解Au NPs形成的反应机制，并深入了解如何针对广泛的实际应用进一步调整纳米颗粒的性质。
