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 UV–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 radicals (OHads), valence band holes (hvb+) and electrons (ecb−), which was verified by studying the effects of scavengers and nitrogen purging.

Compared to I-TiO2 and Ag-TiO2, the photocatalytic activity of Ag-I-TiO2 was enhanced markedly under visible-light irradiation owing to the synergistic effect of Ag and I. The PCP removal increased with increased Ag content up to 3% and then decreased, and the TOC that was used to prove the total mineralization of PCP had a similar trend.Figure optionsDownload high-quality image (125 K)Download as PowerPoint slide