Abstract: ZnFe₂O₄-TiO₂/SiO₂ photocatalysts were prepared by a sol-gel method. Their crystal structure, surface compositions and photo absorption properties were investigated by techniques of differential thermal-thermal gravimetric analysis (DTA-TG), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, temperature programmed reduction (TPR) and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The results show that ZnFe₂O₄ crystallites are highly dispersed on the surface of photocatalysts; a few of Fe³⁺
ions are embedded in the lattice of TiO₂ through the couple of TiO₂ and ZnFe₂O₄. Simultaneously, the excess Zn²⁺ ions on the surface are gathered to form ZnO. The phase transition of TiO₂ starts from bulk and extends to surface with the increase in content of ZnFe₂O₄. The dispersity of active species, such as TiO₂ and ZnFe₂O₄, is enhanced for the addition of SiO2 and the crystal sizes of TiO₂ are smaller than 10nm. The UV absorption limit of photocatalyst tends to bathochromic shift and the percent absorption of visible light is obviously increased by the coupling effect of TiO₂ and ZnFe₂O₄.

Key words: photocatalysis, ZnFe2O4, TiO2, photo absorption property