Studies on a possible growth mechanism of silver nanoparticles loaded on TiO2 thin films by photoinduced deposition method

Abstract The TiO 2 thin films loaded with silver nanoparticles were prepared on soda-lime glass substrates by a photoinduced deposition method. The TiO 2 films immersed in AgNO 3 solution were vertically irradiated by UV light with center wavelength of 365 nm for 60 h. The as-produced films were characterized by X-ray diffraction (XRD), UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The studies show that the film after UV excitation is composed of anatase phase TiO 2 and metallic silver with face centered cubic structure. A possible growth mechanism of silver nanoparticles on TiO 2 thin films under UV irradiation was proposed. The charge carriers of TiO 2 semiconductor are generated by photoexcitation. Owing to the conduction band position of TiO 2 which is above the standard potential of Ag + /Ag, the generated electrons could transfer from the conduction band to Ag + adsorbed on the surface of the TiO 2 films. Therefore, the Ag + was finally reduced into a Ag atom, which could preferentially localize in the grain boundaries of TiO 2 particles due to high surface free energy there. With the irradiation time extended, silver nanoparticles were shaped into certain morphologies on the surface of the TiO 2 films.