Key Lab of Materials Physics, Anhui Key Lab of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China. University of Science and Technology of China, Hefei 230026, People's Republic of China.
Nanotechnology. 2018 Nov 9;29(45):455604. doi: 10.1088/1361-6528/aade27. Epub 2018 Aug 31.
Surface enhanced Raman scattering (SERS) substrates with both high activity and long term chemical-stability have been expected in the practical application of the SERS-based detection. In this paper, Au-Ag bimetal nanocrystals are fabricated based on the template-etching reaction in the Ag nanocubes-contained cetylpyridinium chloride (CPC) aqueous solution via adding the HAuCl solution. The obtained nanocrystals are Au-Ag alloyed and hollow in structure. Further, it has been found that with the increasing Au/Ag molar ratio, the shape of the alloyed nanocrystals evolve from the truncated nanocubes to the hollow boxes and then nanocages, showing the ever red-shifting surface plasmon resonance from the visible to the infrared region. The formation of the alloyed hollow nanocrystals is attributed to the preferential dissolution of the Ag nanocubes induced by CPC selective adsorption and the three to one galvanic replacement reaction between Ag and Au atoms. Importantly, such Au-Ag alloyed hollow nanocrystals, especially the ones with a low Au/Ag atomic ratio, show both high SERS activity and long term environmental stability compared with pure Ag or Au nanocrystals, and are the ideal candidate for the SERS substrate with practical application value. This work not only demonstrates the nanofabrication route to the alloyed hollow nanocrystals with controllable shapes and tunable optical properties in a large region, but also presents highly active and chemically-stable SERS substrates for the practical SERS-based detection.
表面增强拉曼散射（SERS）基底在基于 SERS 的检测的实际应用中，既需要具有高活性，又需要具有长期的化学稳定性。本文通过在含有 Ag 纳米立方体的十六烷基吡啶氯（CPC）水溶液中添加 HAuCl 溶液，基于模板刻蚀反应制备了 Au-Ag 双金属纳米晶体。所得到的纳米晶体为 Au-Ag 合金且具有中空结构。此外，研究发现，随着 Au/Ag 摩尔比的增加，合金纳米晶体的形状从截顶纳米立方体演变为中空盒体，然后是纳米笼体，其表面等离子体共振从可见光区域逐渐红移到红外区域。合金中空纳米晶体的形成归因于 CPC 选择性吸附诱导的 Ag 纳米立方体的优先溶解，以及 Ag 和 Au 原子之间的三对一的电替换反应。重要的是，与纯 Ag 或 Au 纳米晶体相比，这种 Au-Ag 合金中空纳米晶体，特别是具有低 Au/Ag 原子比的纳米晶体，不仅具有高 SERS 活性和长期环境稳定性，而且是具有实际应用价值的 SERS 基底的理想选择。这项工作不仅展示了在较大区域内可控形状和可调谐光学性质的合金中空纳米晶体的纳米制造途径，而且还为实际的基于 SERS 的检测提供了高活性和化学稳定的 SERS 基底。
