Three-dimensional TiO2 supported silver nanoparticles as sensitive and UV-cleanable substrate for surface enhanced Raman scattering

A multifunctional TiO2/Ag nanoparticles (AgNPs) complex substrate was prepared via a three-step approach, which included the hydrothermal route on a Ti substrate, the deposition of Ag by photo-reducing method and the annealing treatment under high temperature. The effect of the annealing process on the morphology, structure and surface-enhanced Raman scattering (SERS) performance of the substrate was systematically investigated, and the optimal substrate was obtained. Herein, 4-aminothiophenol (4-ATP), methylene blue (MB) and crystal violet (CV) were employed as probe molecules to test the sensitivity and UV-cleanable property of the hybrid SERS substrate. The results suggested that the substrate exhibited relatively high enhancement ability, good stability, reproducibility, and recyclability. The synthesised SERS-active substrate was further used to detect thiram molecules, a kind of pesticides, and the limitation of detection in ethanol, apple juice and apple peel reached 10−7 M, 10−6 M and 240 ng/cm2, respectively. The detection limit of thiram in the apple juice was below than the maximal residue limit of 7 ppm (2.9 × 10−5 M) in fruit prescribed by the U.S. Environmental Protection Agency (EPA). These results demonstrated that TiO2/AgNPs complex substrate exhibited promising application with respect to its potential use for on-site detection of residual pesticides.