Changes in the Chemical and Structural Properties of Nanocomposite Ag:TiO2 Films during Photochromic Transitions

Abstract : This study focuses on changes in the oxidation state of silver and in the crystalline phase of TiO2 occurring during the photochromic transitions of amorphous nanocomposite mesoporous Ag:TiO2 films exposed to ultraviolet and visible laser light. The chemical and phase transformations have been investigated by ultraviolet–visible spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, high-angle annular dark field scanning transmission electron microscopy, and high-resolution transmission electron microscopy. The results bring to the fore the presence of both silver nanoparticles in face-centered cubic and hexagonal crystalline phases during the photochromic transitions and a large amount of oxidized silver nanoparticles after visible light exposure, along with nucleation of some TiO2 crystals despite the very low intensity used.