Synthesis, optical, and photocatalytic properties of a new visible-light-active ZnFe2O4–TiO2 nanocomposite material

Abstract

The synthesis of new ZnFe2O4-TiO2 crystalline nanocomposites with enhanced visible- light catalytic performance is reported. Zinc ferrite powders were prepared by a wet method through oxalate precursor at 400 8C during 12 h and the nanocomposite materials were obtained through TiO2 incorporation before (ZnFe2O4/TiO2) and after (TiO2/ ZnFe2O4) the ZnFe2O4 synthesis. The influence of the nanocomposite design in the structural, morphologi- cal, and optical properties of the composite oxide materials was studied, by XRD, SEM/TEM, BET measurements, and DRS. New and improved optical features were observed in the ZnFe2O4-TiO2 absorp- tion spectra comparatively with the TiO2 and ZnFe2O4 ones. These results are discussed based on the interface effect and a proposal for the photogenerated electron transitions in the ZnFe2O4-TiO2 is presented. The photocatalytic performance of the prepared sam- ples was evaluated for the methyl orange (MO) degradation process. From all the tested materials, the TiO2/ZnFe2O4 was the one with the best photo- catalytic activity, even superior to the nanocrystalline TiO2 one. 100 % reduction of the MO concentration was achieved after 10 min of UV-Vis irradiation on a 10 ppm dye aqueous solution with 0.43 g L -1 of TiO2/ZnFe2O4 catalyst. By performing visible-light experiments, it was possible to discuss the influence of the visible-light absorption, charge separation, and photogenerated charge-carrier recombination in the TiO2/ZnFe2O4 photocatalytic performance.