Molecular-Level Insights into Size-Dependent Stabilization Mechanism of Gold Nanoparticles in 1-Butyl-3-methylimidazolium Tetrafluoroborate Ionic Liquid

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• 作者：Fangjia Fu ; Yunzhi Li ; Zhen YangGuobing Zhou ; Yiping Huang ; Zheng Wan ; Xiangshu Chen ; Na Hu ; Wei Li ; Liangliang Huang
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：January 12, 2017
• 年：2017
• 卷：121
• 期：1
• 页码：523-532
• 全文大小：650K
• ISSN：1932-7455

文摘

Here we report a series of classical molecular dynamics simulations for the icosahedral Au nanoparticles with four different diameters of 1.0, 1.4, 1.8, and 2.3 nm in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) room-temperature ionic liquid (RTIL). Our simulation results reveal for the first time a size-dependent stabilization mechanism of the Au nanoparticles in the [bmim][BF₄] RTIL, which may help to clarify the relevant debate on the stabilization mechanism from various experimental observations. By comparison, the alkyl chains in the [bmim]⁺ cations are found to dominate the stabilization of the smallest Au₁₃ nanoparticle in the RTIL while the imidazolium rings should be mainly responsible for the stabilization of other larger nanoparticles in the RTIL. Compared to the [bmim]⁺ cations, the [BF₄]⁻ anions are found to have an indirect influence on stabilizing the Au nanoparticles in the RTIL because of the weak interaction between the Au nanoparticles and the anions. However, such differences in the stabilization mechanism between the small and the large Au nanoparticles can be attributed to the unique hydrogen bond (HB) network between the cations and the anions in the first solvation shell. Meanwhile, increasing the particle size can lead to the enhanced HBs on the surface of Au nanoparticles, so slower rotational motions and more pronounced orientation distribution of cations can be observed around the larger nanoparticles. Our simulation results in this work provide a molecular-level understanding of the unique size-dependent stabilization mechanism of the Au nanoparticles in the imidazolium-based RTILs.