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

Fe2O3/TiO2 heterogeneous photocatalysts with different mass ratios of Fe2O3vs. TiO2 were synthesized by impregnation of Fe3+ on the surface of TiO2 microrods and calcination at 300 °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 Fe2O3/TiO2 heterocomposites, pure Fe2O3 and pure TiO2 were evaluated by the photodegrading efficiency of Orange II under visible light (λ > 420 nm). The experiments demonstrated that Orange II in aqueous solution was more efficiently photodegraded using Fe2O3/TiO2 heterogeneous photocatalysts than either pure Fe2O3 or TiO2 under visible light irradiation. With an optimal mass ratio of 7 : 3 in Fe2O3/TiO2 the highest rate of Orange II photodegradation was achieved under the experimental conditions. We have also compared the photoelectric properties of Fe2O3/TiO2 heterogeneous photocatalysts with that of pure Fe2O3 by surface photovoltage (SPV) and transient photovoltage (TPV) techniques. Based on the photovoltage responses, we discussed the influence of the hetero-interface between Fe2O3 and TiO2 on transfer characteristics of photogenerated charge carriers. We demonstrated that the formation of heterojunctions between Fe2O3 and TiO2 for Fe2O3/TiO2 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.