A combined TEM and SAXS study of the growth and self-assembly of ultrathin Pt nanowires
A combined TEM and SAXS study of the growth and self-assembly of ultrathin Pt nanowires
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DOI：
10.1088/1361-6528/ac893b
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发表时间：
2022-11-19
期刊：
影响因子：
3.5
通讯作者：
Wong，Stanislaus S.
中科院分区：
文献类型：
--
作者：
McGuire，Scott C.;Zhang，Yugang;Wong，Stanislaus S.
超薄铂纳米线具有高活性的各种电催化应用。然而，很少有工作集中在了解其生长机制。在这里，我们利用时间依赖性的，非原位透射电子显微镜（TEM）和小角X射线散射（SAXS）技术的组合，观察生长过程中，除了相关的表面活性剂为基础的相互作用。TEM图像表明，最初的纳米粒子在30秒内形成，这些小的“种子”颗粒迅速伸长，形成纳米线后2分钟。这些图案保持相对不变的大小和形状的反应480分钟。补充SAXS数据表明，最初的纳米粒子，这是由表面活性剂双层涂层，安排成bcc超晶格。随着反应时间的增加，体心立方晶格消失的纳米粒子生长成纳米线，然后自组装成一个柱状的六边形结构，其中各个纳米线被覆盖的CTAB单层。六边形结构最终降解，从而导致形成由表面活性剂双层组成的层状堆叠相。据我们所知，这是第一次，SAXS已被用于监测的Pt纳米线的生长和自组装。这些见解可以用来更好地理解和合理控制其他金属纳米结构的各向异性图案的形成。
Ultrathin Pt nanowires possess high activity for various electrocatalytic applications. However, little work has focused on understanding their growth mechanisms. Herein, we utilize a combination of time-dependent, ex situ transmission electron microscopy (TEM) and small angle x-ray scattering (SAXS) techniques to observe the growth process in addition to associated surfactant-based interactions. TEM images indicate that initially nanoparticles are formed within 30 s; these small'seed'particles quickly elongate to form ultrathin nanowires after 2 min. These motifs remain relatively unchanged in size and shape up to 480 min of reaction. Complementary SAXS data suggests that the initial nanoparticles, which are coated by a surfactant bilayer, arrange into a bcc superlattice. With increasing reaction time, the bcc lattice disappears as the nanoparticles grow into nanowires, which then self-assemble into a columnar hexagonal structure in which the individual nanowires are covered by a CTAB monolayer. The hexagonal structure eventually degrades, thereby leading to the formation of lamellar stacking phases comprised of surfactant bilayers. To the best of our knowledge, this is the first time that SAXS has been used to monitor the growth and self-assembly of Pt nanowires. These insights can be used to better understand and rationally control the formation of anisotropic motifs of other metallic nanostructures.