Corn-like, recoverable γ-Fe₂O₃@SiO₂@TiO₂ photocatalyst induced by magnetic dipole interactions

Corn-like, γ-Fe₂O₃@SiO₂@TiO₂ core/shell heterostructures were synthesized by a modified solvothermal reduction combined with a sol-gel method. SiO₂ shells were first deposited on monodisperse Fe₃O₄ microspheres by a sol-gel method. Fe₃O₄@SiO₂@TiO₂ corn-like heterostructures were then obtained by sequential TiO₂ coating, during which the magnetic dipolar interactions induced the anisotropic self-assembly process. After annealing at 350 °C, the crystalized TiO₂ enhanced photocatalytic activity, while Fe₃O₄ was converted to γ-Fe₂O₃. The corn-like γ-Fe₂O₃@SiO₂@TiO₂ photocatalyst can be recycled and reused by magnet extraction. Despite the photocatalytic activity decreased with each cycle, it can be completely recovered by moderate heating at 200 °C.