Visible-light responsive zinc ferrite doped titania photocatalyst for methyl orange degradation

Visible-light responsive zinc ferrite doped titania (ZFDT) photocatalysts were prepared by sol-gel method. Diffuse Reflectance Spectroscopy (DRS) result shows that the absorption edge of ZFDT has moved to the visible spectrum range and a very large redshift occurs in comparison with the undoped titania. X-ray diffraction (XRD) results show that zinc ferrite can prevent the transformation of titania from anatase to rutile when the content of zinc ferrite is above 1.5%; while the phase transformation is promoted when its content is below 1.5%. In the latter case, zinc ferrite was assumed to exist as separate zinc and ferric cations in the lattice of titania in the form of oxides, both of which promote the phase transformation as previously reported in other literatures. Field emission scanning electron micrography (FE-SEM) shows that the average particle size of 1.5%ZnFe2O4/TiO2 calcined at 500 C is about 70 nm. The photocatalytic experimental results exhibit that ZFDT powders can effectively photodegrade methyl orange under visible light irradiation and the maxium photoactivity is achieved when the amount of zinc ferrite is 1.5%.