Effect of Ag loading content on morphology and photocatalytic activity of Ag-TiO2 nanoparticulate films prepared via simultaneous plasma-enhanced chemical and physical vapor deposition

Abstract

Ag loading is known to enhance the photocatalytic performance of TiO2; however, the correlation between Ag and the resulting changes in TiO2 morphology and particle size is not well understood. A plasma-enhanced chemical vapor deposition (PECVD) and physical vapor deposition (PVD) were used to prepare Ag-TiO2 nanoparticulate thin films; the prepared films were annealed at 500 °C under N2 atmosphere. The Ag content was adjusted by the furnace temperature of the PVD system. Well-dispersed Ag nanoparticles on the surface of TiO2 nanoparticles were observed and analyzed using transmission electron microscopy (TEM). The morphology, particle size, and photocatalytic activity of the films were evidently affected by the Ag content. TEM images showed that the TiO2 nanoparticle size increased with increasing Ag content. Evaluation of the photocatalytic activity based on the degradation of methylene blue under ultraviolet (UV) light irradiation demonstrated that an Ag content of 2.2 wt% yielded the highest photocatalytic activity (5.5 times higher than that seen in a pristine TiO2 film). This fabrication method has advantages because it adds Ag in a more controlled manner compared to the liquid-phase methods. Furthermore, our fabrication method can provide a way to vary the Ag content while considering the relationship between the photocatalytic performance and the Ag content.