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

Abstract This study presents the preparation and the application of γ -Fe 2 O 3 /TiO 2 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 -Fe 2 O 3 /TiO 2 (NT) MHPs were studied. Results show that the MHPs are provided with highly ordered TiO 2 (titania) nanotube arrays (55 nm in diameter and 10 nm in wall thickness) and nano γ -Fe 2 O 3 (maghemite) particle (approximately 15 nm) co-deposition. The MHPs exhibit a superparamagnetic behavior of γ -Fe 2 O 3 /TiO 2 (NT) MHPs resulting from the small size of γ -Fe 2 O 3 particles. The photocatalytic activity of γ -Fe 2 O 3 /TiO 2 (NT) MHPs is greater than that of Fe 3 O 4 /TiO 2 (NT) MHPs or pure TiO 2 (NT) under visible light irradiation. The interaction between γ -Fe 2 O 3 and TiO 2 improves charge separation and extends TiO 2 response into the visible region. Moreover, the formed heterojunction between γ -Fe 2 O 3 and TiO 2 can further prevent the recombination between photoelectrons and holes.