Optical and photocatalytic properties of TiO2/Ag–SiO2 nanocomposite thin films

Abstract

The TiO2/Agx–(SiO2)1−x nanocomposite thin films with a bilayer structure were prepared via a chemical solution approach combined with a sol–gel spin-coating processing. The TiO2/Ag0.15–(SiO2)0.85 thin film is about 200nm in thickness including a top anatase–TiO2 layer approximately 60nm, while the approximately spherical Ag nanoparticles with 10–30nm in diameter were embedded uniformly in the amorphous SiO2 matrix of the sublayer. The UV–Vis absorption peaks appeared in the wavelength of 420nm due to the surface plasmon resonance (SPR) of Ag particles. The SPR peaks manifest a red-shift with increasing Ag content from 6 to 15at.%, whereas blue-shift from 15 to 20at.%. The photocatalytic activity enhanced by increasing Ag content up to 15at.% but reduced by further increasing Ag content. It is found that the optimal Ag loading for achieving the highest photocatalytic activity is 15at.%.