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

Two series of Fe₂O₃/TiO₂samples were prepared via impregnation and photodeposition methods. The effect of preparation method on the properties and performance of Fe₂O₃/TiO₂for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV light irradiation was examined. The Fe₂O₃/TiO₂nanocomposites 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/TiO₂nanocomposites 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 TiO₂after photodeposition of Fe₂O₃was contributed to the formation of a heterojunction between the Fe₂O₃and TiO₂nanoparticles that improved charge transfer and suppressed electron–hole recombination. A further investigation on the role of the active species on Fe₂O₃/TiO₂confirmed that the crucial active species were both holes and superoxide radicals. The Fe₂O₃(0.5)/TiO₂sample also showed good stability and reusability, suggesting its potential for water purification applications.