Galvanic Replacement-Free Deposition of Au on Ag for Core-Shell Nanocubes with Enhanced Chemical Stability and SERS Activity
Galvanic Replacement-Free Deposition of Au on Ag for Core-Shell Nanocubes with Enhanced Chemical Stability and SERS Activity
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DOI：
10.1021/ja502472x
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发表时间：
2014-06-11
影响因子：
15
通讯作者：
Qin, Dong
中科院分区：
文献类型：
--
作者：
Yang, Yin;Liu, Jingyue;Qin, Dong
我们报告了通过直接将Au原子沉积在银纳米立方体表面作为保形超薄壳的Ag@Au核壳纳米立方体的稳健合成。我们的成功依赖于引入一种强还原剂来竞争，从而阻止Ag和HAuCl4之间的电替换。厚度为0.6 nm的超薄金壳能够在氧化环境中保护核心中的银。值得注意的是，核壳纳米立方体具有与原始银纳米立方体基本相同的表面等离子体特性，而SERS活性由于化学增强的改进而进一步提高了5.4倍。优异的SERS活性和化学稳定性的结合可能使各种新的应用成为可能。
We report a robust synthesis of Ag@Au core-shell nanocubes by directly depositing Au atoms on the surfaces of Ag nanocubes as conformal, ultrathin shells. Our success relies on the introduction of a strong reducing agent to compete with and thereby block the galvanic replacement between Ag and HAuCl4. An ultrathin Au shell of 0.6 nm thick was able to protect the Ag in the core in an oxidative environment. Significantly, the core shell nanocubes exhibited surface plasmonic properties essentially identical to those of the original Ag nano cubes, while the SERS activity showed a 5.4-fold further enhancement owing to an improvement in chemical enhancement. The combination of excellent SERS activity and chemical stability may enable a variety of new applications.