Modification Of Iodine Doped Titanium Dioxide For The Photodegradation Of 2-chlorophenol

In the present work, Iodine-doped titania photocatalysts (I-TiO₂) modified by Ga or SnO₂ were synthesized and characterized. The structure and optical properties of the catalysts have been well characterized by X-ray diffraction, the Brunauer-Emmett-Teller method, transmission electron microscopy, UV–visible absorption spectra and X-ray photoelectron spectroscopy. The photocatalytic activity of catalysts were evaluated using 2-chlorophenol (2-CP) as a model compound under visible and/or UV-visible light irradiation.The photoactivities of I-TiO₂ were improved by doping with gallium (Ga,I-TiO₂). We found that Ga probably enters the TiO₂ framework for doping levels <0.5 mol%. A further increase in Ga content probably leads to dispersal of excess Ga on the TiO₂ surface. The results indicate that 0.5 mol% Ga loading and calcination at 400 ?C represent optimal conditions in the calcining temperature range 400–600 ?C and with doping levels from 0.1% to 1 mol%. The effective enhancement of 2-CP degradation might be attributed to the formation of oxygen vacancies by Ga doping, which could decrease the recombination of electron-hole pairs.The photocatalytic degradation of 2-CP irradiated with visible light over I-TiO₂ modified with SnO₂ (SIT) nanoparticles has been investigated in this study. The effects of preparation conditions, such as SnO₂ content and calcination temperature, on the photocatalytic degradation efficiency have been surveyed in detail. The improved photocatalytic activity of SIT is derived from the synergistic effect between the SnO₂ and I-TiO₂, which promoted the efficiency of migration of the photogenerated carriers at the interface of the catalysts and thereby enhanced the efficiency of photon harvesting in the visible region. The action of scavengers (fluoride ion, iodide ion, tert-butyl alcohol, and persulfate ion), as well as N2 purging on the photodegradation rate reveal that the valence band hole is mainly responsible for the effective photocatalytic removal of 2-CP and the corresponding TOC reduction.