Ag@SiO2 core-shell nanoparticles on silicon nanowire arrays as ultrasensitive and ultrastable substrates for surface-enhanced Raman scattering
Ag@SiO2 core-shell nanoparticles on silicon nanowire arrays as ultrasensitive and ultrastable substrates for surface-enhanced Raman scattering
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硅纳米线阵列上的 Ag@SiO2 核壳纳米粒子作为表面增强拉曼散射的超灵敏和超稳定基底
DOI：
10.1088/0957-4484/24/33/335501
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发表时间：
2013-08-23
期刊：
影响因子：
3.5
通讯作者：
Sun, Xiao Ming
中科院分区：
文献类型：
--
作者：
Zhang, Chang Xing;Su, Lei;Sun, Xiao Ming
通过简单的化学刻蚀和金属还原工艺，在银纳米颗粒表面修饰二氧化硅纳米层，形成大规模、均匀的硅纳米线阵列。将这样形成的三维Ag/SiNWAs用作表面增强拉曼散射（Sers）的基底，并且获得了低至10 - 16 M的罗丹明6 G的检测限和高达1014的拉曼增强因子。模拟结果表明，两种三维几何形状的银纳米粒子间的间隙形成了大量的Sers“热点”，在这些热点处，电磁场被显著放大，从而提高了Sers的灵敏度，降低了检测限。Ag/SiNWAs优异的Sers稳定性归因于Ag NP周围SiO2纳米层的存在，其防止了Ag NP表面被氧化。罗丹明6 G和福美双的拉曼峰强度的校准允许它们的定量检测。我们的发现是一个重大的进展，在发展Sers基板的快速和定量检测的痕量有机分子。
Ag nanoparticles (NPs) coated with silica nanolayers were decorated onto a large-scale and uniform silicon nanowire array (SiNWA) by simple chemical etching and metal reduction processes. The three-dimensional Ag/SiNWAs thus formed are employed as a substrate for surface-enhanced Raman scattering (SERS), and a detection limit for rhodamine 6G as low as 10−16 M and a Raman enhancement factor as large as 1014 were obtained. Simulation results show that two kinds of inter-Ag-NP nanogaps in three-dimensional geometry create a huge number of SERS ‘hot spots’ where electromagnetic fields are substantially amplified, contributing to the higher SERS sensitivity and lower detection limit. The excellent SERS stability of Ag/SiNWAs is attributed to the presence of the SiO2 nanolayer around Ag NPs that prevented the Ag NP surface from being oxidized. The calibration of the Raman peak intensities of rhodamine 6G and thiram allowed their quantitative detection. Our finding is a significant advance in developing SERS substrates for the fast and quantitative detection of trace organic molecules.