Characterization of Ligand Adsorption at Individual Gold Nanocubes
Characterization of Ligand Adsorption at Individual Gold Nanocubes
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DOI：
10.1021/acs.langmuir.1c00694
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发表时间：
2021-06-18
期刊：
影响因子：
3.9
通讯作者：
Baker, Lane A.
中科院分区：
文献类型：
--
作者：
Choi, Myung-Hoon;Jeong, Soojin;Baker, Lane A.
十六烷基三甲基溴化铵（CTAB）是一种广泛使用的表面活性剂，有助于胶体纳米颗粒的水相合成。然而，在水合条件下，纳米颗粒表面上残留的CTAB的存在会显著影响纳米颗粒的应用，例如催化和传感。因此，考虑在水合条件下纳米颗粒表面上CTAB的存在和量是重要的。在这里，作为一个综合的材料表征框架的一部分，我们证明了原位原子力显微镜（AFM）的可行性，检测CTAB表面上的Au纳米立方体（Au NC）在水合条件下，这使得上级表征相比，传统的光谱方法。原位力-距离（FD）光谱和开尔文探针力显微镜（KPFM）测量支持吸附的CTAB的额外表征，而相关的原位AFM和扫描电子显微镜（SEM）测量被用来评估CTAB从Au NCs去除的顺序步骤，分别在水合和脱水的环境。值得注意的是，甲醇洗涤后，大量的CTAB保留在Au NC表面上，这在AFM测量中检测到，但在红外光谱测量中没有检测到。随后的电化学清洗被认为是至关重要的，以消除从Au NC表面的CTAB。还对单个纳米颗粒进行了相关测量，这进一步验证了本文所述的方法作为确定从纳米颗粒表面去除CTAB的程度和程度的有力工具。这种基于AFM的方法广泛适用于表征水合条件下纳米材料表面配体的存在和去除。
Cetyltrimethylammonium bromide (CTAB) is a widely used surfactant that aids the aqueous synthesis of colloidal nanoparticles. However, the presence of residual CTAB on nanoparticle surfaces can significantly impact nanoparticle applications, such as catalysis and sensing, under hydrated conditions. As such, consideration of the presence and quantity of CTAB on nanoparticle surfaces under hydrated conditions is of significance. Herein, as part of an integrated material characterization framework, we demonstrate the feasibility of in situ atomic force microscopy (AFM) to detect CTAB on the surface of Au nanocubes (Au NCs) under hydrated conditions, which enabled superior characterization compared to conventional spectroscopic methods. In situ force-distance (FD) spectroscopy and Kelvin probe force microscopy (KPFM) measurements support additional characterization of adsorbed CTAB, while correlative in situ AFM and scanning electron microscopy (SEM) measurements were used to evaluate sequential steps of CTAB removal from Au NCs across hydrated and dehydrated environments, respectively. Notably, a substantial quantity of CTAB remained on the Au NC surface after methanol washing, which was detected in AFM measurements but was not detected in infrared spectroscopy measurements. Subsequent electrochemical cleaning was found to be critically important to remove CTAB from the Au NC surface. Correlative measurements were also performed on individual nanoparticles, which further validate the method described here as a powerful tool to determine the extent and degree of CTAB removal from nanoparticle surfaces. This AFM-based method is broadly applicable to characterize the presence and removal of ligands from nanomaterial surfaces under hydrated conditions.