Photocatalytic degradation of persistent brilliant green dye in water using CeO2/ZnO nanospheres

Abstract In the present work, ceria/zinc oxide (CeO2/ZnO) nanocomposite has been synthesized by controlled annealing of cerium and zinc precursors. The obtained CeO2/ZnO nanocomposite was characterized using common analytical methods such as Fourier transform infrared spectroscopy (FT-IR), UV-Visible diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectrum (SEM with EDS) and elemental mapping measurements. The band gap energy of CeO2/ZnO nanocomposite was about ∼2.9 eV calculated from the Tauc plot. The XRD pattern of CeO2/ZnO nanocomposite consisted mixed phases of CeO2 and ZnO with crystalline nature. The XPS spectrum of CeO2/ZnO revealed the presence of C, Zn, N, O and Ce elements, where Zn and Ce existed in 2+ and 4+ oxidation states, respectively. The particle size and shape of synthesized CeO2/ZnO nanocomposite was approximately 0.32 µm with a distorted spherical shape identified from the SEM images. The synthesized CeO2/ZnO nanocomposite effectively degraded BG in water and the calculated kinetic rate constant was 0.0471 min-1. The results suggested that CeO2/ZnO nanocomposite behave as a good photocatalyst towards the degradation of BG, identified from the quick degradation as compared with pure ZnO and CeO2. The enhanced catalytic performance of CeO2/ZnO nanocomposite was attributed to the synergistic effect of both CeO2 and ZnO semiconductors, which decrease the bandgap energy and increase the degradation kinetics.