Synthesis, characterization and investigation of optical and photocatalytic properties of zinc oxide nanoparticles in three different rod, spherical and sheet morphologies

In the present study, zinc oxide nanoparticles in three different forms (spherical, rod and sheet) were synthesized by a hydrothermal method. The obtained products were characterized by X-ray diffraction (XRD), filed emission scanning electron microscopy (FESEM), EDX elemental analysis and UV-Vis spectroscopy. The photocatalytic properties were investigated using congo red (CR) degradation under ultraviolet iradiation . ZnO nanorods exhibited higher photocatalytic activity as compared to other morphologies (sheet and spherical) that occurred with a 97% destruction rate within two hours at pH = 8. The energy gap of the synthesized nanoparticles was calculated by tauc method and the relationship between the obtained values ​​and the photocatalytic activity of the particles was investigated. It was found that, the efficiency of the photacatalytic reaction is more dependent on the particle size and morphology than on the band gap. The kinetics results showed the first-order reaction mechanism for the photocatalytic activities of the nanoparticles