Morphological Changes of Silica Shells Deposited on Gold Nanorods: Implications for Nanoscale Photocatalysts
Morphological Changes of Silica Shells Deposited on Gold Nanorods: Implications for Nanoscale Photocatalysts
复制标题
DOI：
10.1021/acsanm.1c00977
复制
发表时间：
2021-07-28
影响因子：
5.9
通讯作者：
Chen，Yu
中科院分区：
文献类型：
--
作者：
Adelt，Milan;MacLaren，Donald A.;Chen，Yu
金纳米棒 (GNR) 支持强大的局部表面等离子体共振，可用于增强相邻分子的荧光或催化特性。用二氧化硅涂覆 GNR 经常用于对其表面进行功能化，但完全封装限制了控制分子空间分布及其相关反应性的能力。例如，将分子定位在 GNR 末端附近将能够利用其强大的纵向等离子共振，但这种选择性具有挑战性。到目前为止，各向异性涂层的研究还很有限，GNR 上的吸附机制仍不清楚。在这里，我们系统地研究了 GNR 末端二氧化硅的各向异性涂层以及生长条件对二氧化硅壳形成的影响。观察到了三种类型的纳米结构并描述了它们的起源：完全封装的核壳 GNR、仅一端涂有二氧化硅的 GNR 以及两端涂有哑铃状 GNR（dGNR）。该研究在室温左右进行，可以调节表面活性剂十六烷基三甲基溴化铵 (CTAB) 的溶解度和胶束化，以影响所得二氧化硅壳的形态、稳定性和密度。优化的参数与适当的 GNR 纵横比相结合，可以显着提高 dGNR 的生长产量，从而成为主导产品。开发了 dGNR 高产率合成方案，最大产率超过 90%。这项研究增进了我们对 GNR 各向异性涂层生长机制的理解，并为优化位点选择性涂层工艺提供了线索。用于荧光/散射放大器的各向异性 GNR 纳米结构的开发对于金属增强荧光、表面增强拉曼散射或等离子体增强催化等应用非常重要。
Gold nanorods (GNRs) support strong localized surface plasmon resonances that can be exploited to enhance the fluorescence or catalytic properties of adjacent molecules. Coating GNRs with silica is frequently used to functionalize their surfaces, but full encapsulation limits the ability to control the spatial distribution of molecules and their related reactivity. For example, locating molecules near the ends of GNRs would enable their strong longitudinal plasmon resonance to be exploited, but such selectivity is challenging. So far, studies of anisotropic coating have been limited and the mechanism of the adsorption onto GNRs remains unclear. Here, we systematically investigated the anisotropic coating of the ends of GNRs with silica and the influence of growth conditions on the formation of silica shells. Three types of nanostructures have been observed and their origins are described: fully encapsulated core–shell GNRs, GNRs with only one end coated with silica, and dumbbell-like GNRs (dGNRs) with both ends coated. The study was performed at around room temperature, where the solubility and micellization of the surfactant cetyltrimethylammonium bromide (CTAB) can be tuned to affect the morphology, stability, and density of resulting silica shells. Optimized parameters, in combination with an appropriate GNR aspect ratio, are shown to significantly improve the growth yield of dGNRs, which become the dominant product. A protocol for a high-yield synthesis of dGNRs was developed, with a maximum yield exceeding 90%. This study advances our understanding of the growth mechanism of anisotropic coating of GNRs and sheds light on the optimization of site-selective coating processes. The development of anisotropic GNR-based nanostructures for fluorescence/scattering amplifiers will be important in applications such as metal-enhanced fluorescence, surface-enhanced Raman scattering or plasmon-enhanced catalysis.