Enhancement of the photocatalytic performance of Ag-modified TiO2 photocatalyst under visible light

A highly visible-light photocatalytic active Ag-modified TiO2 (Ag-TiO2) was prepared by a simple sot gel process using TiOSO4 as the starting material, AgNO3 as a silver doping source, and hydrazine as a reducing agent. The prepared Ag-TiO2 samples were characterized by several techniques such as X-ray powder diffraction (XRD), BET surface area measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), energy dispersive X-ray spectrometry (EDX), X-ray absorption spectroscopy (XAS) and UV-vis diffuse reflectance spectroscopy (DRS). The Ag-TiO2 photocatalyst, a mixture of amorphous and anatase phases, has a high surface area. The silver contents in the Ag-TiO2 samples were determined by ICP measurements. The diffused reflectance UV-vis spectra indicated that the Ag-TiO2 samples exhibited higher red shifts compared with the undoped TiO2 sample. Indigo carmine degradation under visible irradiation indicated that the Ag-TiO2 catalyst gave higher photocatalytic efficiency than those of commercial P25-TiO2 and undoped-TiO2 samples. The Ag-TiO2 catalyst can be reused many times without any additional treatment. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.