Highly sensitive multifunctional recyclable Ag–TiO2 nanorod SERS substrates for photocatalytic degradation and detection of dye molecules

Abstract

We report a facile method to fabricate novel Ag nanoparticle decorated TiO₂ nanorod array substrates using a glancing angle deposition (GLAD) technique for photocatalysis and surface enhanced Raman scattering (SERS) applications. The silver nanoparticles on the TiO₂ nanorods enhances the Raman signal of rhodamine 6G (Rh6G) dye with an enhancement factor ∼10⁵. The photocatalytic degradation of Rh6G molecules present on Ag nanoparticle decorated TiO₂ nanorods (Ag–TiO₂) was also studied. The intensity of the Rh6G peak at 611 cm⁻¹ decreases considerably (∼99%) after UV irradiation for 90 minutes. The change in SERS enhancement with time during ultra-violet (UV) light irradiation was used to track the photocatalytic degradation of the dye present on the Ag–TiO₂ nanorods. The Ag–TiO₂ SERS substrates can be recovered after 150 min in the presence of UV light illumination. The as-prepared Ag–TiO₂ nanorods could be self-regenerated, fully recovered, and recycled after their use in the SERS analysis because of the self-cleaning property of TiO₂ under simple UV light irradiation. This excellent SERS enhancement may be attributed to the formation of high density hotspots on top of the TiO₂ nanorods which is supported by finite difference time domain (FDTD) simulations.