High photocatalytic activity of Fe(2)O(3)/TiO(2) nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid

Two series of Fe(2)O(3)/TiO(2) samples were prepared via impregnation and photodeposition methods. The effect of preparation method on the properties and performance of Fe(2)O(3)/TiO(2) for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV light irradiation was examined. The Fe(2)O(3)/TiO(2) nanocomposites prepared by impregnation showed lower activity than the unmodified TiO(2), mainly due to lower specific surface area caused by heat treatment. On the other hand, the Fe(2)O(3)/TiO(2) nanocomposites prepared by photodeposition showed higher photocatalytic activity than the unmodified TiO(2). Three times higher photocatalytic activity was obtained on the best photocatalyst, Fe(2)O(3)(0.5)/TiO(2). The improved activity of TiO(2) after photodeposition of Fe(2)O(3) was contributed to the formation of a heterojunction between the Fe(2)O(3) and TiO(2) nanoparticles that improved charge transfer and suppressed electron–hole recombination. A further investigation on the role of the active species on Fe(2)O(3)/TiO(2) confirmed that the crucial active species were both holes and superoxide radicals. The Fe(2)O(3)(0.5)/TiO(2) sample also showed good stability and reusability, suggesting its potential for water purification applications.