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

Abstract

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.

Plasmonic-TiO2 Nanohybrid for Environmental and Energy Applications

“…The correspondingly formed Schottky junction promotes the transfer of generated hot-electrons towards the conduction band of TiO 2 from the metal-semiconductor interface. Thus, the SERS activity of Ag/TiO 2 hybrid substrates is mainly governed by the three contributions, namely, the plasmonic NPs, the transition of electrons between the highest occupied molecular orbital (HOMO) energy level, and the lowest unoccupied molecular orbital (LUMO) energy level of analyte molecule and initiation of charge transfer between the Fermi level of Ag nanoparticle and HOMO level of the analyte molecule, as explained by Zhao et al for adsorbed R6G molecules over surface of Ag/TiO 2 nanowire substrates [63].…”