Intensifying the photocatalytic degradation of methylene blue by the formation of BiFeO3/Fe3O4 nanointerfaces

A novel highly efficient photocatalyst composite BiFeO3/Fe3O4 has been synthesized by mechanosynthesis and applied to the degradation of Methylene Blue under visible light. Structural, optical and photocatalytic properties of the proposed photocatalyst composites are carefully investigated. The nanointerfaces, associated to ferrous Fe2+ ions of the Fe3O4 nanoparticles, improve the photocatalytic efficiency when compared with pure BiFeO3/Fe3O4. The time required to the complete degradation of Methylene Blue solution is 40 min for the sample with 20% of Fe3O4 which is more than 7 times faster than the time required using BiFeO3 alone. Moreover, with the addition of H2O2 a complete degradation is achieved just after 10 min, which is faster than any other photocatalytic reaction reported for BiFeO3-based materials. This enhancement is assumed to be related to an electron drain process due to the difference between energy levels of the conduction bands of BiFeO3 and Fe3O4 combined with the direct Fenton-like process associated with the Fe2+ ions of the composites.