Department of Chemical Sciences, University of Padova, via Marzolo 1, I-35131 Padova, Italy.
Nanoscale. 2014;6(3):1423-33. doi: 10.1039/c3nr04995g.
Nanoalloys of noble metals with transition metals are crucial components for the integration of plasmonics with magnetic and catalytic properties, as well as for the production of low-cost photonic devices. However, due to synthetic challenges in the realization of nanoscale solid solutions of noble metals and transition metals, very little is known about the composition dependence of plasmonic response in nanoalloys. Here we demonstrate for the first time that the elemental composition of Au-Fe nanoalloys obtained by laser ablation in liquid solution can be tuned by varying the liquid environment. Due to surface passivation and reaction with thiolated ligands, the nanoalloys obtained by our synthetic protocol are structurally and colloidally stable. Hence, we studied the dependence of the surface plasmon resonance (SPR) on the iron fraction and, for the first time, we observed surface enhanced Raman scattering (SERS) in Au-Fe nanoalloys. SPR and SERS performances are strongly affected by the iron content and are investigated using analytical and numerical models. By demonstrating the strong modification of plasmonic properties on the composition, our results provide important insights into the exploitation of Au-Fe nanoalloys in photonics, nanomedicine, magneto-plasmonic and plasmon-enhanced catalysis. Moreover, our findings show that several other plasmonic materials exist beyond gold and silver nanostructures.
贵金属与过渡金属的纳米合金是将等离子体与磁性和催化性能集成以及制造低成本光子器件的关键组成部分。然而，由于在实现贵金属和过渡金属纳米尺度固溶体方面存在合成挑战，对于等离子体响应在纳米合金中的成分依赖性知之甚少。在这里，我们首次证明，通过在液体溶液中激光烧蚀获得的 Au-Fe 纳米合金的元素组成可以通过改变液体环境来调节。由于表面钝化和与巯基配体的反应，我们通过合成方案获得的纳米合金在结构和胶体上都是稳定的。因此，我们研究了表面等离子体共振（SPR）对铁分率的依赖性，并且首次在 Au-Fe 纳米合金中观察到表面增强拉曼散射（SERS）。SPR 和 SERS 性能强烈受铁含量的影响，并使用分析和数值模型进行了研究。通过证明在组成上对等离子体性质的强烈修饰，我们的结果为在光子学、纳米医学、磁等离子体学和等离子体增强催化中利用 Au-Fe 纳米合金提供了重要的见解。此外，我们的研究结果表明，除了金和银纳米结构之外，还有其他几种等离子体材料存在。
