High photocatalytic activity of Fe₂O₃/TiO₂nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid

Abstract

Two series of Fe₂O₃/TiO₂ samples were prepared via impregnation and photodeposition methods. The effect of preparation method on the properties and performance of Fe₂O₃/TiO₂ for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV light irradiation was examined. The Fe₂O₃/TiO₂ nanocomposites prepared by impregnation showed lower activity than the unmodified TiO₂, mainly due to lower specific surface area caused by heat treatment. On the other hand, the Fe₂O₃/TiO₂ nanocomposites prepared by photodeposition showed higher photocatalytic activity than the unmodified TiO₂. Three times higher photocatalytic activity was obtained on the best photocatalyst, Fe₂O₃(0.5)/TiO₂. The improved activity of TiO₂ after photodeposition of Fe₂O₃ was contributed to the formation of a heterojunction between the Fe₂O₃ and TiO₂ nanoparticles that improved charge transfer and suppressed electron-hole recombination. A further investigation on the role of the active species on Fe₂O₃/TiO₂ confirmed that the crucial active species were both holes and superoxide radicals. The Fe₂O₃(0.5)/TiO₂ sample also showed good stability and reusability, suggesting its potential for water purification applications.