Characterization of iron-doped titania sol-gel materials

Fe/TiO₂ materials at 1 wt% Fe content have been prepared by the addition of aqueous solutions of FeCl₂ to titanium n-tetrabutoxide using hydrochloric acid (pH 3) as a hydrolysis catalyst. The obtained gel was thermally treated at 200, 400, 600 and 800°C. Characterization of the materials was performed by FTIR, UV-Vis, Mössbauer and X-ray powder diffraction. FTIR spectra of the calcined samples showed the presence of highly hydroxylated TiO₂. The XRD patterns show the coexistance of brookite, anatase and rutile TiO₂ phases in samples treated up to 600°C. In the sample treated at 800°C rutile was the only phase observed. UV-Vis spectroscopy revealed that the band gap E_g of the samples increased with increased thermal treatment temperature. Mössbauer spectroscopy showed the coexistance of Fe²⁺ and Fe³⁺ on the TiO₂ samples treated at high temperatures.