Photo-Fenton degradation of organic pollutants using a zinc oxide decorated iron oxide/reduced graphene oxide nanocomposite

Herein, we report a magnetically-separable tertiary composite, zinc oxide-decorated iron oxide deposited reduced graphene oxide (ZnO-Fe3O4/rGO), as a heterogeneous catalyst for photo-Fenton degradation of organic pollutants in aqueous media under ambient conditions. In this study, zinc oxide nanoparticles were hydrothermally deposited on the surface of Fe3O4/GO composite that was synthesized by a solvothermal process. The physicochemical properties of the as-synthesized composite were explored using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) studies. The as-prepared catalyst showed superior stability and, due to the presence of the magnetic Fe3O4 nanospheres, could be conveniently separated from the reaction system with an external magnet for reuse. The as-synthesized, ZnO-Fe3O4/rGO composite exhibited superior catalytic activity for the degradation of azo-dye compared to pristine ZnO, ZnO/Fe3O4, Fe3O4, and Fe3O4/GO. These results revealed the synergistic effects between the different components of the catalyst and confirmed the rapid redox reaction between Fe2+ and Fe3+. It was also observed that this catalytic behavior could be reproduced in consecutive experiments without a considerable decrease in efficiency. All of these merits indicate that the composite catalyst is a promising candidate for the degradation of organic compounds under visible light in environmental remediation applications.