†Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States.
‡Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States.
Nano Lett. 2015 Jun 10;15(6):4161-9. doi: 10.1021/acs.nanolett.5b01286. Epub 2015 May 7.
Au nanorods are optically tunable anisotropic nanoparticles with built-in catalytic activities. The state-of-the-art seed-mediated nanorod synthesis offers excellent control over the aspect ratios of cylindrical Au nanorods, which enables fine-tuning of plasmon resonances over a broad spectral range. However, facet control of Au nanorods with atomic-level precision remains significantly more challenging. The coexistence of various types of low-index and high-index facets on the highly curved nanorod surfaces makes it extremely challenging to quantitatively elucidate the atomic-level structure-property relationships that underpin the catalytic competence of Au nanorods. Here we demonstrate that cylindrical Au nanorods undergo controlled facet evolution during their overgrowth in the presence of Cu(2+) and cationic surfactants, resulting in the formation of anisotropic nanostructures enclosed by well-defined facets, such as low-index faceting nanocuboids and high-index faceting convex nanocuboids and concave nanocuboids. These faceted Au nanorods exhibit enriched optical extinction spectral features, broader plasmonic tuning range, and enhanced catalytic tunability in comparison to the conventional cylindrical Au nanorods. The capabilities to both fine-tailor the facets and fine-tune the plasmon resonances of anisotropic Au nanoparticles open up unique opportunities for us to study, in great detail, the facet-dependent interfacial molecular transformations on Au nanocatalysts using surface-enhanced Raman scattering as a time-resolved spectroscopic tool.
金纳米棒是具有内置催化活性的光学可调各向异性纳米粒子。目前的种子介导的纳米棒合成技术可以很好地控制圆柱状金纳米棒的纵横比，从而可以在较宽的光谱范围内微调等离子体共振。然而，要实现原子级精度的金纳米棒的晶面控制仍然具有很大的挑战性。高度弯曲的纳米棒表面上存在各种类型的低指数和高指数晶面，这使得定量阐明支撑金纳米棒催化能力的原子级结构-性能关系变得极具挑战性。在这里，我们证明了在 Cu(2+)和阳离子表面活性剂的存在下，金纳米棒在生长过程中会发生受控的晶面演化，从而形成由明确定义的晶面封闭的各向异性纳米结构，例如低指数晶面化的纳米立方体、高指数晶面化的凸纳米立方体和凹纳米立方体。与传统的圆柱形金纳米棒相比，这些具有晶面的金纳米棒表现出丰富的光吸收光谱特征、更宽的等离子体调谐范围和增强的催化可调性。精细调整各向异性金纳米粒子的晶面和精细调整等离子体共振的能力为我们提供了独特的机会，可以使用表面增强拉曼散射作为时间分辨光谱工具，详细研究金纳米催化剂上的界面分子转化。
