Our paper has been accepted by Journal of the American Chemical Society. 

Title: Fully alloyed Ag/Au nanospheres: Combining the plasmonic property of Ag with the stability of Au

Authors: C. Gao,* Y. Hu, M. Wang, M. Chi, Y. Yin*

Link to the Publisher: http://pubs.acs.org/doi/abs/10.1021/ja502890c

Highlight by XJTU: http://news.xjtu.edu.cn/info/1004/42342.htm

Abstract: In this work we report that fully alloyed Ag/Au nanospheres with high compositional homogeneity ensured by annealing at elevated temperatures show large extinction cross-sections, extremely narrow band-widths and remarkable stability in harsh chemical environments.  As is well known, Ag nanostructures show much stronger surface plasmon resonance than those made of Au.  However, their application in sensing, imaging, therapy, energy harvesting, or many other areas has been very limited due to their poor chemical stability against non-ideal chemical environment.  In this work, we aim to address this issue by producing fully alloyed Ag/Au nanospheres through a surface-protected high-temperature annealing process.  The resulting structure show homogeneous distribution of the Ag and Au elements across a whole nanosphere, minimal crystallographic defects, absence of structural and compositional interfaces, which account for the extremely narrow bandwidths of the surface plasmon resonance.  The Au/Ag alloy nanospheres are thus concluded to have Ag-like plasmonic property and Au-like stability, which may render many plasmonic applications with high performance and long lifetime, especially for those involving corrosive species.  We believe this work may have significant impact to many fields including biomedical engineering, analytical chemistry, materials science, physics, and environmental science.

中文简介：

金、银等贵金属纳米材料具有表面等离子体共振性质，因此在分子检测、生物传感、成像及催化等领域具有广阔的应用价值。长期以来，该类材料的发展受到光学性 能（如金）和化学稳定性（如银）等方面的限制，制约了它们的应用范围及性能的提升。本论文提出了一种新颖的思路，借助二氧化硅的表面保护作用，使金银双金 属纳米粒子中各成分在高温（930℃以上）下实现充分合金化，最终得到了兼具优异的光学性质和化学稳定性的金银合金纳米粒子。该材料可在酸、碱、强氧化性 等多种复杂环境下稳定存在，大大拓展了其应用范围，并在各种基于表面等离子体共振的应用中表现出优异的性能。为此，本论文初步展示了使用该材料通过表面增 强拉曼光谱在工业废水中高效检测特定污染物的能力。

该工作发表在化学材料领域顶级期刊《美国化学会志》（影响因子：13.038）上。