TiO 2 /Fe 2 O 3 heterostructures with enhanced photocatalytic reduction of Cr(vi) under visible light irradiation.

We report a study on the synthesis of TiO 2 /Fe 2 O 3 (TF) nanocomposites and their photocatalytic performance under visible-light irradiation. The characterization of structure and morphology shows that hematite Fe 2 O 3 was deposited on anatase TiO 2 nanoparticles with particle sizes in the range of 20-100 nm. In contrast to pure TiO 2 and pure Fe 2 O 3 , the nanocomposites exhibited remarkable photocatalytic activity. For example, the photoreduction efficiency of TF0.5 reaches 100% for a 100 ppm Cr(vi) solution within 160 minutes. The photochemical properties were studied by various methods. Finally, we conclude that the excellent performance of the photocatalysts is mainly attributed to two aspects: the enhanced absorption of visible light and the synergistic effect of an internal electric field at the heterojunction and citric acid for promoting the separation of electron-hole pairs.