SERS-active substrates based on Ag-coated TiO2 nanotubes and nanograss

In this work, TiO2 nanotubes (NT) and nanograss (NG) at the edges of nanotubes obtained by electrochemical anodizing followed by the deposition of plasmonic silver (Ag, 30 μg/cm2) nanoparticles were investigated as substrates for surface enhanced Raman scattering (SERS) on methylene blue molecules. The resulting nanotubes have an inner diameter of about 40–80 nm and a wall thickness of ∼10 nm. Synthesis parameters were worked out for the formation of nanograss on the edges of TiO2 nanotubes. The deposition of an active silver layer with respect to surface plasmon resonance on the TiO2 nanostructures makes it possible to use this composite as efficient SERS substrates. It was found that the proposed SERS systems allow to detect the Raman spectrum of methylene blue (MB) at concentrations down to 10−12 M. The values of the analytical enhancement factor for TiO2 NT and NG at the edges of nanotubes were estimated with respect to different reference materials.