期刊
NANO LETTERS
卷 19, 期 9, 页码 6308-6314出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.9b02434
关键词
ligand characterization; ligand binding density; gold nanorods; cetyltrimethylammonium bromide; electron energy loss spectroscopy; scanning transmission electron microscopy
类别
资金
- Packard Foundation Fellowship
- National Science Foundation [DMR-1846206, CHE-1608743, CHE-1503408, DMR-1720633]
A longstanding challenge in nanoparticle characterization is to understand anisotropic distributions of organic ligands at the surface of inorganic nanoparticles. Here, we show that using electron energy loss spectroscopy in an aberration-corrected scanning transmission electron microscope we can directly visualize and quantify ligand distributions on gold nanorods (AuNRs). These experiments analyze dozens of particles on graphene substrates, providing insight into how ligand binding densities vary within and between individual nanoparticles. We demonstrate that the distribution of cetyltrimethylammonium bromide (CTAB) on AuNRs is anisotropic, with a 30% decrease in ligand density at the poles of the nanoparticles. In contrast, the distribution of (16-mercaptohexadecyl)trimethylammonium bromide (MTAB) is more uniform. These results are consistent with literature reported higher reactivity at the ends of CTAB-coated AuNRs. Our results demonstrate the impact of electron spectroscopy to probe molecular distributions at soft-hard interfaces and how they produce spatially heterogeneous properties in colloidal nanoparticles.
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