Synthesis, photoelectric properties and photocatalytic activity of the Fe2O3/TiO2 heterogeneous photocatalysts.

Fe(2)O(3)/TiO(2) heterogeneous photocatalysts with different mass ratios of Fe(2)O(3)vs. TiO(2) were synthesized by impregnation of Fe(3+) on the surface of TiO(2) microrods and calcination at 300 degrees C. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), photoluminescence spectra and X-ray diffraction (XRD) have been used to characterize the samples. The photocatalytic activities of Fe(2)O(3)/TiO(2) heterocomposites, pure Fe(2)O(3) and pure TiO(2) were evaluated by the photodegrading efficiency of Orange II under visible light (lambda > 420 nm). The experiments demonstrated that Orange II in aqueous solution was more efficiently photodegraded using Fe(2)O(3)/TiO(2) heterogeneous photocatalysts than either pure Fe(2)O(3) or TiO(2) under visible light irradiation. With an optimal mass ratio of 7:3 in Fe(2)O(3)/TiO(2) the highest rate of Orange II photodegradation was achieved under the experimental conditions. We have also compared the photoelectric properties of Fe(2)O(3)/TiO(2) heterogeneous photocatalysts with that of pure Fe(2)O(3) by surface photovoltage (SPV) and transient photovoltage (TPV) techniques. Based on the photovoltage responses, we discussed the influence of the hetero-interface between Fe(2)O(3) and TiO(2) on transfer characteristics of photogenerated charge carriers. We demonstrated that the formation of heterojunctions between Fe(2)O(3) and TiO(2) for Fe(2)O(3)/TiO(2) composites was pivotal for improving the separation and thus restraining the recombination of photogenerated electrons and holes, which accounts for the enhancement of photocatalytic activity.