Magnetic recyclable α-Fe2O3–Fe3O4/Co3O4–CoO nanocomposite with a dual Z-scheme charge transfer pathway for quick photo-Fenton degradation of organic pollutants

Abstract

The integration of multiple degradation pathways in a single catalyst is a potential approach to advance the technologies of organic pollutant degradation. To integrate both the heterogeneous photo-Fenton reaction and Z-scheme configuration in a single catalyst, a novel magnetic separable α-Fe₂O₃–Fe₃O₄/Co₃O₄–CoO nanocomposite enriched with oxygen vacancies is fabricated via the solution combustion method by optimizing the fuel and nitrate ion concentration. The Z-scheme configuration along with oxygen vacancies contributes to in situ H₂O₂ generation and simultaneous reactivation with high H₂O₂ performance, which is required for the photo-Fenton process. Oxygen vacancies facilitate the charge carrier transfer in the Z-scheme system and promote interfacial electronic transmission involved in the redox cycle from Co^III/Fe^III to Co^II/Fe^II, inducing the generation of ˙O₂⁻, ¹O₂, ˙SO₄⁻ and ˙OH radicals. Consequently, the transcendental catalyst exhibits excellent photo-Fenton photocatalytic features facilitating highly improved pollutant degradation under sunlight irradiation and Fenton reaction promoting the degradation in the dark as well. The photodegradation rate is enhanced 5.33 times and 3.6 times in the presence of H₂O₂ and persulfate, respectively. This study opens the possibility of designing a single catalyst with different degradation mechanisms.