The effects of synthesis temperature on the structure and visible-light-induced catalytic activity of F-N-codoped and S-N-codoped titania

F-N-codoped and S-N-codoped titania photocatalysts have been synthesized at different temperatures by a chemical procedure. Here titanium tetrachloride, NH4F and thiourea were used as precursors of titania, fluorine and nitrogen, sulfur and nitrogen, respectively. The as-prepared codoped titania were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-visible diffuse reflectance spectra (UV-vis DRS). XRD patterns showed the as-synthesized photocatalysts to be anatase. Increasing reactive temperature from 313 to 413 K enhanced the crystallinity and led to an increase in grain size. UV-vis DRS revealed that the visible absorption ability improved in the range of 400-620 nm with decreasing temperature. Photocatalytic decomposition of methyl orange (MO) carried out in the visible region (>= 420 nm) showed that the codoped titania prepared at low temperature possessed over three times of percentage of degradation of MO than that of P25 titania. The mechanism of synthesis of codoped titania at low temperature was also discussed primary. (c) 2008 Elsevier B.V. All rights reserved.