Title : Newly developed surface-enhanced Raman scattering active substrates with excellent reproducibility.
As a powerful analytic technique, Raman scattering intensity from molecules in close proximity to the surface of certain finely divided metals, especially for nanostructured Ag, Au and Cu, can be significantly enhanced by a factor of 106 or even higher. Generally, aggregation of Ag or Au nanoparticles (NPs) has emerged as a promising strategy to produce large enhancement of surface-enhanced Raman scattering (SERS). However, the SERS signal reproducibility would be poor due to the unavoidably random field distribution. To hold both high SERS effect and satisfactory reproducibility fabrication of ordered array of SERS-active substrates is most popularly adopted, but the corresponding procedure is always complicated. In this work, we report on an innovative and facile one-step fabrication of SERS-active Au and Ag substrates with improved SERS activity and excellent signal reproducibility by using simple oxidation-reduction cycles (ORC) in 0.1 N KCl. In this new strategy, hot electron transfer-induced activated (HETIA) water is utilized instead of conventional deionized (DI) water. Experimental results indicate that the corresponding SERS effect of Au or Ag substrate prepared in HETIA-based solution is higher than that prepared in DI water-based solution. The SERS-active Au and Ag substrates prepared in AuNT water- based solutions demonstrate large enhancement factors (EFs) of 8.5 ×107 and 6.2 ×108, respectively. More importantly, the excellent reproducibility of the signal intensity of Rhodamine 6G (R6G) is observed on SERS-active both Au and Ag substrates prepared in HETIA water-based solutions. In measuring solid samples, the corresponding relative standard deviations (RSDs) are 6 and 17% for Au and Ag substrates, respectively. In measuring liquid samples, the corresponding RSDs can be significantly reduced to ca. 1.6 and 8.1% for two batches of experiments. These low RSDs, which are comparable to and even more excellent than those shown in the literature, reported in this simple but innovative strategy can promise its reliable application in SERS- related studies.