High Visible-light Photocatalytic Activity of γ-Fe2O3/TiO2 Nanotube Heterojunction Arrays

This study presents the preparation and the application of γ-Fe2O3/TiO2 nanotube magnetic heterojunction photocatalysts (MHPs) for photodegradation of methylene blue under visible light irradiation. The morphology, the microstructure, the magnetic properties and the photocatalytic activity of γ-Fe2O3/TiO2 (NT) MHPs were studied. Results show that the MHPs are provided with highly ordered TiO2 (titania) nanotube arrays (55 nm in diameter and 10 nm in wall thickness) and nano γ-Fe2O3 (maghemite) particle (approximately 15 nm) co-deposition. The MHPs exhibit a superparamagnetic behavior of γ-Fe2O3/TiO2 (NT) MHPs resulting from the small size of γ-Fe2O3 particles. The photocatalytic activity of γ-Fe2O3/TiO2 (NT) MHPs is greater than that of Fe3O4/TiO2 (NT) MHPs or pure TiO2 (NT) under visible light irradiation. The interaction between γ-Fe2O3 and TiO2 improves charge separation and extends TiO2 response into the visible region. Moreover, the formed heterojunction between γ-Fe2O3 and TiO2 can further prevent the recombination between photoelectrons and holes.