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

Abstract

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.