The impact of silver modification on the catalytic activity of iodine-doped titania for p-chlorophenol degradation under visible-light irradiation

Iodine-doped titania photocatalysts (I-TiO2) were improved by doping the catalysts with different contents of silver (Ag-I-TiO2) to investigate the effect of silver modification on the structure and activity of the photocatalysts. The chemical and physical properties of the catalysts were determined by X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, transmission electron microscopy (TEM), selected area electron diffraction pattern (SAED). X-ray photoelectron spectroscopy (XPS), and OV-vis diffuse reflectance spectra. The impact of silver modification on the photocatalytic activity was investigated via the photodegradation of p-chlorophenol (PCP) under visible-light irradiation. The significant enhancement of PCP degradation using Ag-I-TiO2, with an optimum silver content of 3% can be ascribed to the fact that the doped silver trapped photogenerated electrons and promoted the formation of Ti3+ and, hence, the inhibition of the recombination of electron-hole pairs. The probable pathway of PCP mineralization was mainly a surface charge process, caused by adsorbed (OH)-O-center dot radicals (center dot OHads), valence band holes (h(vb)(+)) and electrons (e(cb)(-)), which was verified by studying the effects of scavengers and nitrogen purging. (C) 2009 Elsevier B.V. All rights reserved.