Stimulating Multiple SERS Mechanisms by a Nanofibrous Three-Dimensional Network Structure of Titanium Dioxide (TiO₂)

A unique 3-D nanostructure is generated from pure Ti by a pulsed femtosecond laser. The resulting crystalline TiO2 nanofibers in a 3-D nanonetwork were found to be significant contributors to surface-enhanced Raman spectroscopy (SERS). Overall, the analytical enhancement factor was calculated to be 1.3 × 106 based on a crystal violet dye. Based on our best knowledge as well as SEM, TEM, EDX, and AFM studies, high Raman activity may be occurring by multiple mechanisms including nanogap, nanocluster, and plasmonic hybridization. This important result rivals silver (Ag) and gold (Au) as the most popular SERS substrates. The novelty of our presented work implies a potential approach to prepare traditionally inactive substrates for Raman biomolecular sensing and chemical detection studies.