The Preparation And Photocatalytic Performance Of Iodine-doped Titanium Dioxide

In this thesis, TiO₂ doped with iodine photocatalysts I-TiO₂ are prepared by a hydrothermal method. The photocatalytic degradation of methyl orange(MO) is used as model reaction to evaluate the visible-light photocatalytic activity of the photocatalysts. The effects of preparation and reaction conditions on the visible-light photocatalytic performances are studied. The structure of catalysts and their photoelectrical performance are systematically studied by using TG/DSC,XRD,Zeta Potential,BET,UV-Vis DRS,HRTEM,EFISPS and XPS. A proposed mechanism of visible-light photocatalysis is also discussed.The results show that: (1)The iodine-doped TiO₂ photocatalysts prepared by the hydrothermal method have small crystalline size, large specific surface area and mesoporous structure, and show good photocatalytic performance under visible light. (2)The photocatalytic degradation of MO on I-TiO₂ is significantly affected by the iodine doping amount and calcination temperature.The optimum doping amount and calcination temperature are 6.8 wt% and 300℃, respectively.(3)The optimum sample (IT300) also shows high photocatalytic activity at degradating salicylic acid and acetone.(4)We propose a visible-light photocatalysis mechanism of IT300. The mechanium includes: iodine doping produced I7+ impurity midgap levels, when the catalyst is illuminated with visible light a electron is promoted from the valence band of TiO₂ into the impurity midgap levels and the electrons are trapped by I7+ which caused the high separation efficiency of electrons and holes. The holes are trapped by surface hydroxyls to form hydroxyl radicals and then the pollutants are degralated by hydroxyl radicals.This work, for the first time, introduces the photocatalyst I-TiO₂ prepared by the hydrothermal method, which shows good photocatalytic activity under visible light. The structural and photoelectric properties of such photocatalyst are studied, and a proposed mechanism of visible-light photocatalysis for I-dopping TiO₂ is also discussed. Keywords:...