Plasmonic SERS active nanostructured Ag–SiO2 at optimum volume ratio synthesized via sol-gel technique

Abstract Plasmonic nanostructured silver silica at an optimum volume ratio of silver silica and constant concentration of silver nanoparticles (AgNPs) was successfully synthesized by the sol-gel technique for surface-enhanced Raman scattering (SERS) application. Transmission electron microscopy (TEM) images confirm that the optimum ratio of the nanostructures consists of SiO2 particles partially penetrated and embedded by the Ag NPs with a mean particle size of 35 nm, which are homogeneous and spherical in shape. UV–vis spectroscopy of the optimum ratio shows that the intensity of the Ag–SiO2NCs peak is greatly reduced with a clear and sharp absorption peak. 4-Aminobenzenethiol (4-ABT) as the probe molecule greatly enhances the SERS signal. The results from different pH values confirm that the substrate is stable and gives the strongest SERS enhancements in a highly alkaline environment.