Characterization and reactivity of Fe3O4/FeMnOx core/shell nanoparticles for methylene blue discoloration with H2O2

A magnetic core/shell Fe3O4/FeMnOx catalyst was prepared by a simple oxidation–precipitation method. The catalyst was characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and cyclic voltammetry. The characterization studies verified that Fe3O4 core was coated with a layer of Fe–Mn oxide. The Fe3O4/FeMnOx was found to be an effective and stable heterogeneous catalyst for the discoloration of methylene blue (MB) in aqueous solution by H2O2. The high catalytic activity is due to the FeMnOx shell, which not only increased the surface hydroxyl groups, but also enhanced the interfacial electron transfer. The discoloration of MB could be due to the decomposition of H2O2 into OH and the adsorption of MB on Fe3O4/FeMnOx.

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► In this manuscript, a magnetic core/shell Fe3O4/FeMnOx catalyst is prepared by a simple oxidation–precipitation method.
► Fe3O4/FeMnOx is an effective and stable heterogeneous catalyst for the discoloration of methylene blue (MB) in aqueous solution at different pH.
► The catalyst shell not only increases the surface hydroxyl groups, but also enhances the electron transfer, resulting in higher activity.
► The discoloration of MB is promoted due to the decomposition of H2O2 into OH and the adsorption of MB on Fe3O4/FeMnOx.