Enhanced visible-light driven photocatalytic activity of ag@tio₂ photocatalyst prepared in chitosan matrix

Ag doped TiO₂ photocatalysts (Ag@TiO₂ ) were prepared with an aim to extend the absorption range of TiO₂ into the visible region, for tentative application under solar irradiation. Photocatalyst synthesized by the novel method using chitosan for reduction of Ag⁺ to Ag⁰ nanoparticles was compared to similar catalysts previously reported. The photocatalytic activity of Ag@TiO₂ obtained by a simple novel method was evaluated based on degradation of salicylic acid as a model compound. The higher activity under visible irradiation can be attributed to the surface plasmon resonance and suppression of the electron-hole recombination when deposition of Ag nanoparticles on TiO₂ was achieved using chitosan. The photocatalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), high resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDXS), selected area diffraction (SAED), and diffuse reflectance spectroscopy (DRS). The photochromism of Ag was observed and explained.