Ag-Ag2S Hybrid Nanoprisms: Structural versus Plasmonic Evolution
Ag-Ag2S Hybrid Nanoprisms: Structural versus Plasmonic Evolution
复制标题
Ag-Ag2S 混合纳米棱镜：结构演化与等离子体演化
DOI：
10.1021/acsnano.6b01532
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发表时间：
2016-05-01
期刊：
影响因子：
17.1
通讯作者：
Mirkin, Chad A.
中科院分区：
文献类型：
--
作者：
Shahjamali, Mohammad M.;Zhou, Yong;Mirkin, Chad A.
最近，Ag-Ag2S杂化纳米结构由于其增强的化学和热稳定性以及其形态和成分依赖性的可调谐局部表面等离子体共振而引起了广泛的关注。虽然 Ag-Ag2S 纳米结构可以通过硫化所制备的各向异性银纳米颗粒来合成，但人们对这一过程知之甚少，通常会导致材料具有异常的成分、尺寸和形状，从而导致光学性能异常。在这项工作中，我们利用理论和实验研究了Ag前驱体硫化过程中Ag-Ag2S纳米棱柱的结构和等离子体演化。先前观察到的 Ag-Ag2S 混合纳米棱柱在硫化时发生红移消光与理论预测相矛盾，表明反应并不像先前推测的那样仅发生在棱柱尖端。我们的实验表明，根据反应条件，硫化可以引起偶极等离子体模式消光的蓝移或红移。通过阐明合成的Ag-Ag2S纳米棱柱与最终结构和形貌的相关性，我们发现，根据反应条件，在棱柱尖端和/或（111）表面上发生硫化，形成核（Ag）-各向异性壳（Ag2S）棱柱纳米结构。此外，我们证明偶极等离子体激元的移动方向是棱镜尖端 Ag2S 相对量和棱镜周围 Ag2S 壳厚度的函数。
Recently, Ag-Ag2S hybrid nanostructures have attracted a great deal of attention due to their enhanced chemical and thermal stability, in addition to their morphology- and composition-dependent tunable local surface plasmon resonances. Although Ag-Ag2S nanostructures can be synthesized via sulfidation of as-prepared anisotropic Ag nanoparticles, this process is poorly understood, often leading to materials with anomalous compositions, sizes, and shapes and, consequently, optical properties. In this work, we use theory and experiment to investigate the structural and plasmonic evolution of Ag-Ag2S nanoprisms during the sulfidation of Ag precursors. The previously observed red-shifted extinction of the Ag-Ag2S hybrid nanoprism as sulfidation occurs contradicts theoretical predictions, indicating that the reaction does not just occur at the prism tips as previously speculated. Our experiments show that sulfidation can induce either blue or red shifts in the extinction of the dipole plasmon mode, depending on reaction conditions. By elucidating the correlation with the final structure and morphology of the synthesized Ag-Ag2S nanoprisms, we find that, depending on the reaction conditions, sulfidation occurs on the prism tips and/or the (111) surfaces, leading to a core(Ag)-anisotropic shell(Ag2S) prism nanostructure. Additionally, we demonstrate that the direction of the shift in the dipole plasmon is a function of the relative amounts of Ag2S at the prism tips and Ag2S shell thickness around the prism.