Controllable Charge Transfer in Ag-TiO(2) Composite Structure for SERS Application

The nanocaps array of TiO(2)/Ag bilayer with different Ag thicknesses and co-sputtering TiO(2)-Ag monolayer with different TiO(2) contents were fabricated on a two-dimensional colloidal array substrate for the investigation of Surface enhanced Raman scattering (SERS) properties. For the TiO(2)/Ag bilayer, when the Ag thickness increased, SERS intensity decreased. Meanwhile, a significant enhancement was observed when the sublayer Ag was 10 nm compared to the pure Ag monolayer, which was ascribed to the metal-semiconductor synergistic effect that electromagnetic mechanism (EM) provided by roughness surface and charge-transfer (CT) enhancement mechanism from TiO(2)-Ag composite components. In comparison to the TiO(2)/Ag bilayer, the co-sputtered TiO(2)-Ag monolayer decreased the aggregation of Ag particles and led to the formation of small Ag particles, which showed that TiO(2) could effectively inhibit the aggregation and growth of Ag nanoparticles.