Ag-Doped TiO₂ Composite Films Prepared Using Aerosol-Assisted, Plasma-Enhanced Chemical Vapor Deposition

TiO₂ is a promising photocatalyst, but its large bandgap restricts its light absorption to the ultraviolet region. The addition of noble metals can reduce the bandgap and electron-hole recombination; therefore, we prepared TiO₂-Ag nanoparticle composite films by plasma-enhanced chemical vapor deposition (PECVD) using a mixture of aerosolized AgNO₃, which was used as a Ag nanoparticle precursor, and titanium tetraisopropoxide, which acted as the TiO₂ precursor. Notably, the use of PECVD enabled a low process temperature and eliminated the need for pre-preparing the Ag nanoparticles, thereby increasing the process efficiency. The structures and morphologies of the deposited films were characterized by ultraviolet (UV)—visible spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy, and the effects of the AgNO₃ concentration on the photocatalytic activity of the deposited films were determined by assessing the degradation of methylene blue under UV light irradiation. The Ag ions were successfully reduced to metallic nanoparticles and were embedded in the TiO₂ film. The best photocatalytic activity was achieved for a 1 wt% Ag-loaded TiO₂ composite film, which was 1.75 times that of pristine TiO₂.