Sol-gel synthesis of mesoporous mixed Fe2O3/TiO2 photocatalyst: Application for degradation of 4-chlorophenol

Abstract

Photosensitization of TiO2 with other transition metal oxides can extend its light absorption property in the visible region. Such materials could emerge as excellent catalysts for solar photocatalytic degradation. In the present study mesoporous Fe2O3/TiO2 (10, 30, 50, 70 and 90wt% Fe2O3) photocatalysts were synthesized by sol-gel process and characterized using different techniques. The XRD patterns exhibited the presence of mesoporous structure and isomorphic substitution of Fe3+ in TiO2 at low Fe3+ loading and Ti4+ in Fe2O3 at high Fe3+ loading. The XPS results revealed the presence of Ti4+ and Fe3+ in Fe2O3/TiO2 materials. The DRS UV-vis spectra showed a shift in the band gap excitation of TiO2 to longer wavelength, thus illustrating incorporation of Fe3+ in TiO2. In addition, free TiO2 and Fe2O3 particles were also present. Their photocatalytic activity was tested for the degradation of 4-chlorophenol in aqueous medium using sunlight. The activity of the catalysts followed the order: meso-30wt% Fe2O3/TiO2>meso-10wt% Fe2O3/TiO2>meso-50wt% Fe2O3/TiO2>meso-70 Fe2O3/TiO2>meso-90wt% Fe2O3/TiO2>meso-Fe2O3>meso-TiO2. This order concluded that mesoporous Fe2O3/TiO2 could be an active catalyst for pollutant degradation, as TiO2 with framework Fe3+ and photosensitization with free Fe2O3 were involved in the activity. © 2013 Elsevier B.V.