Enhanced SERS performance of cavity-hosting silver dendrites grown over TiO2 nanotubes
Alba Arenas-Hernández, Umapada Pal
Abstract
• The key parameters for electrochemical synthesis of oriented Ag-Ds over TiO 2 nanotubes (TiO 2 -NT) were identified. • Ag-Ds with cavities formed over TiO 2 -NT support were grown at optimized conditions. • Cavity-hosting Ag-Ds deposited over TiO 2 -NT revealed a SERS enhancement factor as high as 10 9 . • The high analytic enhancement factor of the Ag-Ds is associated with the combined effect of chemical enhancement, electromagnetic enhancement, and cavity resonance. Silver nanostructures, utilized as SERS substrates, consistently exhibit exceptional performance in detecting organic compounds through Raman spectroscopy, primarily due to the electromagnetic enhancement mechanism. This study explores an advanced SERS substrate composed of cavities formed by silver dendrites (Ag-Ds) on TiO 2 nanotubes (TiO 2 -NT), demonstrating exceptional performance in detecting organic compounds through Raman spectroscopy. TiO 2 -NT acts as a template, guiding the nucleation and growth of Ag-D to create the cavity structures. The deposition time of silver significantly influences substrate performance in detecting Rhodamine 6G (R6G) and Ibuprofen (IB). It has been observed that an extended deposition time diminishes the enhancement factor. In contrast, a shorter deposition time yields notable enhancement due to the combined effects of electromagnetic and chemical enhancement mechanisms. An optimum deposition time limits dendrite growth, forming cavities where the electric field couples with multiple light reflections, further amplifying the SERS enhancement. The cavity-hosted Ag-D/TiO 2 -NT substrate achieves an impressive analytic SERS enhancement factor of up to 2 × 10 9 , enabling the detection of R6G and IB at a low detection limit of 10 -12 M.