Effects of the silver nanodots on the photocatalytic activity of mixed-phase TiO2

Abstract

We present the synthesis and photocatalytic properties of mixed-phase TiO2 nanoparticles decorated with silver nanodots obtained by environmental-friendly wet chemical method using low molecular weight chitosan as the silver reducing agent. Structural analysis of synthesized Ag nanoparticles revealed that they crystallized in a rare hexagonal modification. High-resolution transmission electron microscopy study shows that lt 3-nm hexagonal-Ag nanoparticles are implanted on the surface of lt 20-nm anatase grains. Compared to Ag-free TiO2 powders, implantation with Ag results in important increase in visible light absorption. The photocatalytic activity of the samples was measured by monitoring decolorization of concentrated textile dye solution (50 mg L-1 of Reactive Orange 16) under simulated solar irradiation of 280 W m(-2). The optimum photocatalytic properties are achieved with 5 wt% of silver. Based on the collected results, the operating mechanism of the degradation process is suggested, and the effects of the silver addition are explained.