Visible-Light-Driven Photocatalytic Activity of Ag-Loaded TiO₂ Nanoparticulate Thin Film Fabricated via PECVD-PVD Method

TiO₂ is known for its strong photocatalytic activity for the degradation of organic pollutants. However, the activity is limited to UV light irradiation. Metal-based nanoparticles have been introduced to enhance the absorbance and activity of TiO₂ in the visible light region. The localized surface plasmon resonance (LSPR) effect of the metal improved the degradation efficiency in the visible light region. In this study, Ag was introduced into TiO₂ nanoparticulate thin films using a simultaneous one-step plasma-enhanced chemical vapor deposition and physical vapor deposition (PECVD-PVD) method. Metal Ag nanoparticles were prepared using a simple gas-phase PVD method. Adding Ag to TiO₂ increases the light absorption for longer wavelengths of light irradiation. The existence of Ag was confirmed by the LSPR absorbance peak originating from the Ag nanoparticles. Further analysis of the Ag nanoparticles was also conducted using X-ray photoelectron spectroscopy, which confirmed the stability of Ag metal upon annealing in N₂ atmosphere. The functionality of the nanoparticulate thin films was tested for the degradation of rhodamine 6 G under visible light irradiation, revealing an optimum concentration of 0.24 wt% Ag content exhibited the best activity compared to our fabricated pristine TiO₂ nanoparticulate thin film and even commercial TiO₂ nanoparticles immobilized on a substrate. This paper presents the potential for producing films composed of nanoparticles through a one-step aerosolized process toward broadening the application scope of photocatalysts in the visible light region.