Surface enhanced Raman scattering substrate with high-density hotspots fabricated by depositing Ag film on TiO2-catalyzed Ag nanoparticles

摘要

Surface enhanced Raman scattering (SERS) has been developed as a powerful tool for detection of ultra-trace molecules, thus at foundation of a number of important technologies, such as chemical analysis and biosensor. Photocatalytic growth of Ag nanoparticles (NPs) by TiO2 film is a cost-effective, facile and surfactantless way to fabricate SERS substrates with high stability and reproducibility, but the SERS activity still needs to be improved. In this work, we report a facile way to improve SERS activity of TiO2-catalyzed Ag NPs by additionally depositing a layer of Ag film using magnetron sputtering. Combining with the advantages of liquid and vapor environment, the Ag NPs size increase to the resonance size without decrease of density, so the spacing of Ag NPs decrease and high-density hotspots can be formed. By optimizing the sputtering time of Ag films, the SERS activity of the Ag NPs/films is improved by a factor of similar to 400. This work not only establish a low-cost method for fabricating high-quality SERS substrate, more importantly, propose a novel way to prepare plasmonic nanostructures with high-density hotspots. (C) 2016 Elsevier B.V. All rights reserved.