Co3O4-ZnO/rGO catalyst preparation and rhodamine B degradation by sulfate radical photocatalysis

The development of a combined photocatalytic system with peroxymonosulfate (PMS) has great potential applications in the degradation and treatment of aqueous organic pollutants. Herein, a Co3O4-ZnO/rGO was prepared by a hydrothermal method using cobalt acetate, zinc acetate, and reduced graphene oxide (rGO) as the main raw materials. The physical and chemical characteristics of the obtained catalyst were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). The photocatalytic features and capacities of the catalytic materials to activate PMS were investigated. Co3O4-ZnO/rGO exhibited stronger photocatalytic activity and ability to activate PMS than Co3O4/rGO or ZnO/rGO, and significantly improved the ability of PMS and photocatalysis to synergistically degrade rhodamine B (RhB), with a degradation rate of 90.40% within 40 min. The mechanism of RhB degradation was proposed based on characterization of materials, evaluation of RhB degradation efficiency, and analysis of the active species involved. The unique particle/sheet structure of Co3O4-ZnO/rGO provides a large number of active sites, and the formation of heterojunctions between Co3O4 and ZnO improves carrier separation and transport in the reaction system. Our study offers a reference for designing more effective heterojunction catalysts based on the combination of PMS and photocatalytic technology.