Influence of annealing temperature on the photocatalytic efficiency of sol-gel dip-coated ZnO thin films in methyl orange degradation
A.H. Haritha, Manuel E. Cruz, O. Sisman, Alicia Durán, Dušan Galusek, J. J. Velázquez, Yolanda Castro
Abstract
ZnO thin films on glass substrates and silicon wafers were prepared by the sol-gel dipcoating technique and annealed at temperatures ranging from 300 - 550 °C. X-ray diffraction (XRD) and Raman analysis confirm the hexagonal wurtzite structure of ZnO. Scanning electron microscopy (SEM) examination confirmed that the films were homogeneous, crack-free and with a uniform distribution of nano-sized spherical grains. The decomposition of methyl orange (MO) using a solar simulator was used to determine the photocatalytic activity of the thin films . The annealing temperature was found to have a significant influence on the structure, morphology, and photocatalytic performance of ZnO thin films. The best photocatalytic activity under solar irradiation was shown by the ZnO thin film annealed at 450 °C. The enhanced photocatalytic performance of the films can be attributed to their optimized crystallinity, surface roughness and morphology, which provide more active sites for the photocatalytic reactions.