High photocatalytic activity of ZnO and ZnO:Al nanostructured films deposited by spray pyrolysis

Zinc oxide and aluminum doped zinc oxide films were produced using the spray pyrolysis technique. The substrate temperature and the solution flow rate were varied to optimize the surface morphology of the films. Different concentrations of aluminum were added to the precursor solution in Al/Zn = 0.05, 0.10, 0.25, and 0.50 to study the effect on the photocatalytic activity of ZnO. The films were characterized by profilometry, scanning electron microscopy (SEM), X-ray diffraction (XRD) and the photocatalytic activity was tested by the decomposition of methyl orange dye under UV illumination. The addition of aluminum did not change the ZnO crystalline structure, but changed the surface morphology and increased the photocatalytic activity of ZnO films reducing the time taken to degrade an 80% of the dye from 4 to only 1.25 h.