Visible-light photocatalytic decolorization of dye using urea doped TiO_2

The photocatalytic N/TiO2 doped with different amount of urea was prepared by sol-gel method.Doped urea has little impact on the sol′s mean particle size which is about 30-50 nm.The doping of urea doesn′t make the absorption threshold wavelength have an obvious red-shift.However,it leads to an increase in optical absorption intensity in the visible-light region.FI-IR spectra indicate that urea involves in the hydrolysis process of tetrabutyl titanate and forms a new covalent bond.TiO2 doped with 0.01% and 0.1% urea can increase visible-light photoactivity of the catalyst.The activity decreases as the doping amount continues to increase.The high initial concentration of the dye solution results in a decrease in the decolorization ratio.0.01% N/TiO2 decolors methylene blue solution(4 mg/L) under visible light and the color removal of 92.8% is reached.