Photocatalytic activity of nanocrystalline ZnO, α-Fe2O3 and ZnFe2O4/ZnO

Nanocrystalline powders of ZnO, alpha-Fe2O3 and ZnFe2O4/ZnO were prepared by solution combustion method. The characterization of the nano powders was done by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The ZnO and alpha-Fe2O3 nanopowders exhibited the wurtzite and hexagonal phases, respectively. The PXRD pattern of ZnFe2O4/ZnO indicated the spinel phase of zinc ferrite and wurtzite phase of zinc oxide. The three nanopowders were used as photocatalysts for the removal of the azodye brilliant yellow (BY) from its aqueous solution. A comparison of the results indicated that ZnFe2O4/ZnO showed better photocatalytic activity for the removal of BY than ZnO and alpha-Fe2O3. This was attributed to the synergistic effect between ZnFe2O4 and ZnO resulting in better charge separation and reducing the electron-hole recombination. The photocatalytic activity followed the order: ZnO < alpha-Fe2O3 < ZnFe2O4/ZnO.