Li Xiaocheng, Tay Beng Kang, Li Junshuai, Tan Dunlin, Tan Chong Wei, Liang Kun
School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
Nanoscale Res Lett. 2012 Apr 3;7(1):205. doi: 10.1186/1556-276X-7-205.
Large-area mildly reduced graphene oxide (MR-GO) monolayer films were self-assembled on SiO2/Si surfaces via an amidation reaction strategy. With the MR-GO as templates, MR-GO-Ag nanoparticle (MR-GO-Ag NP) hybrid films were synthesized by immersing the MR-GO monolayer into a silver salt solution with sodium citrate as a reducing agent under UV illumination. SEM image indicated that Ag NPs with small interparticle gap are uniformly distributed on the MR-GO monolayer. Raman spectra demonstrated that the MR-GO monolayer beneath the Ag NPs can effectively quench the fluorescence signal emitted from the Ag films and dye molecules under laser excitation, resulting in a chemical enhancement (CM). The Ag NPs with narrow gap provided numerous hot spots, which are closely related with electromagnetic mechanism (EM), and were believed to remarkably enhance the Raman signal of the molecules. Due to the co-contribution of the CM and EM effects as well as the coordination mechanism between the MR-GO and Ag NPs, the MR-GO-Ag NP hybrid films showed more excellent Raman signal enhancement performance than that of either Ag films or MR-GO monolayer alone. This will further enrich the application of surface-enhanced Raman scattering in molecule detection.
通过酰胺化反应策略，大面积轻度还原氧化石墨烯（MR-GO）单层膜自组装在SiO2/Si表面上。以MR-GO为模板，通过在紫外光照射下将MR-GO单层浸入含有柠檬酸钠作为还原剂的银盐溶液中，合成了MR-GO-银纳米颗粒（MR-GO-Ag NP）混合膜。扫描电子显微镜图像表明，颗粒间间隙小的Ag NPs均匀分布在MR-GO单层上。拉曼光谱表明，Ag NPs下方的MR-GO单层在激光激发下能有效淬灭Ag膜和染料分子发出的荧光信号，从而产生化学增强（CM）。具有窄间隙的Ag NPs提供了大量热点，这与电磁机制（EM）密切相关，并且被认为能显著增强分子的拉曼信号。由于CM和EM效应的共同作用以及MR-GO与Ag NPs之间的配位机制，MR-GO-Ag NP混合膜表现出比单独的Ag膜或MR-GO单层更优异的拉曼信号增强性能。这将进一步丰富表面增强拉曼散射在分子检测中的应用。
