Understanding the Microscopic Origin of Gold Nanoparticle Anisotropic Growth from Molecular Dynamics Simulations
Understanding the Microscopic Origin of Gold Nanoparticle Anisotropic Growth from Molecular Dynamics Simulations
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DOI：
10.1021/la403843n
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发表时间：
2013-12-03
期刊：
影响因子：
3.9
通讯作者：
Sulpizi, Marialore
中科院分区：
文献类型：
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作者：
Meena, Santosh Kumar;Sulpizi, Marialore
我们使用分子动力学模拟，以了解在金纳米棒的不对称生长机制的微观起源。我们提供了第一个原子模型的不同表面上的金纳米粒子在不断增长的电解质溶液中，我们描述的金属与表面活性剂，即十六烷基三甲基溴化铵（CTAB）和离子的相互作用。一个创新的方面是包括表面活性剂的作用，这是明确建模。我们发现，在所有研究的表面，即（111），（110），和（100），CTAB形成一层扭曲的圆柱形胶束之间的通道胶束提供直接的离子进入表面。特别是，我们展示了如何AuCl 2-离子，这是在生长溶液中发现的，可以自由地从本体溶液扩散到金表面。我们还发现，（111）表面具有较高的CTAB堆积密度和较高的静电势。这两种元素都有利于金纳米粒子沿着（11 I）方向生长。这些发现与Murphy和Mulvaney实验组提出的生长机制一致。
We use molecular dynamics simulations in order to understand the microscopic origin of the asymmetric growth mechanism in gold nanorods. We provide the first atomistic model of different surfaces on gold nanoparticles in a growing electrolyte solution, and we describe the interaction of the metal with the surfactants, namely, cetyltrimethylammonium bromide (CTAB) and the ions. An innovative aspect is the inclusion of the role of the surfactants, which are explicitly modeled. We find that on all the investigated surfaces, namely, (111), (110), and (100), CTAB forms a layer of distorted cylindrical micelles where channels among micelles provide direct ion access to the surface. In particular, we show how AuCl2- ions, which are found in the growth solution, can freely diffuse from the bulk solution to the gold surface. We also find that the (111) surface exhibits a higher CTAB packing density and a higher electrostatic potential. Both elements would favor the growth of gold nanoparticles along the (11 I) direction. These findings are in agreement with the growth mechanisms proposed by the experimental groups of Murphy and Mulvaney.