Synthesis, magnetization and photocatalytic activity of LaFeO3 and LaFe0.5Mn0.5−xO3−δ

Perovskite LaFe0.5Mn0.5O3−δ and LaFeO3 were synthesized by stearic acid solution combustion method. The obtained powders were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Vibrating sample magnetometer (VSM), XPS techniques and UV–vis absorption spectra techniques. The magnetic properties of the LaFeO3 and LaFe0.5Mn0.5O3−δ were measured, and they were also evaluated for their photocatalytic activity towards the degradation of methyl orange (MO) under the sunlight irradiation. The experimental results show that the catalytic activities of the LaFe0.5Mn0.5O3−δ were much higher than those of LaFeO3 due to its higher oxygen vacancies, variable valency Mn ions and the strong absorption in visible light. The optimum conditions for photocatalytic degradation MO using LaFe0.5Mn0.5O3−δ were achieved. The ferromagnetism of the LaFe0.5Mn0.5O3−δ could be caused by the Mn3+/Fe3+ and Mn3+/Mn4+double exchange interaction, Mn3+/Mn3+ superexchange interactions as well as the defective state in LaFe0.5Mn0.5O3−δ. The LaFe0.5Mn0.5O3−δ is applicable to the magnetic separation process for its lower coercivity (Hc) and remanent magnetization (Mr), and it can be reusable and maintain relatively high activity.

► The LaFe0.5Mn0.5O3−δ is a bifunctional photocatalyst.
► The origin of the ferromagnetism of the LaFe0.5Mn0.5O3−δ is discussed.
► LaFe0.5Mn0.5O3−δ shows much higher photocatalytic activity than that of LaFeO3.
► LaFe0.5Mn0.5O3−δ can be recycled by an external magnetic field and redispersed again.