Bian Juncao, Li Qian, Huang Chao, Guo Yao, Zaw Myowin, Zhang Rui-Qin
Department of Physics and Materials Science and Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR, China.
Phys Chem Chem Phys. 2015 Jun 14;17(22):14849-55. doi: 10.1039/c4cp05803h.
The application of Ag nanostructures to surface-enhanced Raman scattering (SERS) is hindered by their chemical instability. Fabrication of durable Ag-based SERS substrates is therefore of great significance in practical applications. In this work, ultrathin C-layer-encapsulated Ag nanoparticle arrays (UCL-Ag-NAs) are successfully fabricated on the surface of indium-tin-oxide (ITO) glass, using a hydrothermal method, for use as durable SERS substrates. The problem of Ag nanoparticles dissolving during the hydrothermal process is solved by using ZnO powder as a pH-buffering reagent. The SERS signal intensity of UCL-Ag-NAs decreases, accompanied by an improvement in Raman signal stability, as the C-layer thickness increases. Raman spectra show that the SERS signal intensities obtained from UCL-Ag-NAs with C-layers of 4.5 nm and 7.3 nm stored for 180 days are 64.9% and 77.8% of those obtained from as-prepared counterparts. The SERS intensity of the UCL-Ag-NA (C-layer of 4.5 nm) is 152.7% that of the bare Ag NA after 180 days of storage. XPS spectra confirm that the C-layer effectively suppresses the oxidation of the Ag NA. This methodology can be generalized to improve the durability of other dimensional Ag nanostructures for SERS applications.
银纳米结构在表面增强拉曼散射（SERS）中的应用因其化学不稳定性而受到阻碍。因此，制备耐用的银基SERS基底在实际应用中具有重要意义。在这项工作中，采用水热法在氧化铟锡（ITO）玻璃表面成功制备了超薄碳层包裹的银纳米颗粒阵列（UCL-Ag-NAs），用作耐用的SERS基底。通过使用氧化锌粉末作为pH缓冲试剂，解决了水热过程中银纳米颗粒溶解的问题。随着碳层厚度的增加，UCL-Ag-NAs的SERS信号强度降低，同时拉曼信号稳定性提高。拉曼光谱表明，碳层厚度为4.5 nm和7.3 nm的UCL-Ag-NAs储存180天后获得的SERS信号强度分别是刚制备的对应物的64.9%和77.8%。储存180天后，UCL-Ag-NA（碳层厚度为4.5 nm）的SERS强度是裸银纳米阵列的152.7%。X射线光电子能谱（XPS）证实碳层有效地抑制了银纳米阵列的氧化。这种方法可以推广应用于提高其他尺寸银纳米结构在SERS应用中的耐久性。
