Ag Nanoparticles Synthesized on Black-Titanium Dioxide by Photocatalytic Method as Reusable Substrates of Surface-Enhanced Raman Spectroscopy

The construction of excellent surface-enhanced Raman spectroscopy (SERS) substrates needs rationally designed architectures of noble metals or semiconductors. In this study, Ag nanoparticles (NPs) are densely and uniformly synthesized on the surfaces of black-titanium dioxide (b-TiO2) NPs through a facile two-step photocatalysis method. The b-TiO2 improved the utilization efficiency of natural sunlight by the extension of light absorption from the ultraviolet (UV) to the visible (Vis) region. First, Ag seeds were densely grown in a short time on the surfaces of b-TiO2 NPs under the irradiation of UV light. Then, Ag NPs were grown slowly and uniformly from the Ag seeds under the irradiation of Vis light. The as-prepared Ag/b-TiO2 with high sensitivity achieved a limit of detection as low as 10−12 M for rhodamine 6G. Meanwhile, the substrate showed reusability due to the high photocatalytic ability of b-TiO2. The Ag/b-TiO2 SERS substrate achieves SERS detections of organic pollutants, such as hydroquinone, p-phenylenediamine, and terephthalic acid, indicating that this substrate possesses potential applications in food safety and environmental monitoring.