| The photocatalytic technology under visible light is an important field with practical value. Based on reviewing the machanism of photocatalysis under visible light and some new visible-light-induced photocatalysts, SrFeO3-x-based photocatalysts with perovskite crystal phase were prepared and their performances in the photodegradation of methylene blue(MB) were studied systematically under visible light irradiation. The results showed that the SrFeO3-x presented here possessed high photocatalytic activity under visible light, endowing such materials with extensive application prospect in the treatment of waste dye water. The main contents discussed in this dissertation were as follows:1. SrFeO3-x (0＜x＜0.5) with perovskite crystal phase was prepared via a hydrothermal-citrate method and was characterized by X-ray diffraction (XRD), UV-Vis diffusion reflection spectrum (DRS-UV-Vis), transmission electron microscope (TEM), surface photovoltage spectrum (SPS), and electric-field induced surface photovoltage spectroscopy (EFISPS). XRD results indicated that the resulting SrFeO3-x consisted of nanoparticles with cubic perovskite phase, and its band gap was estimated to be ca. 2.0eV from the DRS-UV-Vis spectra. SPS and EFISPS showed that SrFeO3-x had good response to visible light. Photocatalytic degradation of methylene blue (MB) dye was first investigated over SrFeO3-x photocatalyst under visible light irradiation (λ≥430nm). It is found that the SrFeO3-x possessed high photocatalytic activity under visible light irradiation.2. The photocatalytic activities of SrFeO3-x prepared by different method and under various conditions were studied systematically. Compared with the SrFeO3-x synthesized by traditional citrate method, the SrFeO3-x prepared by the hydrothermal-citrate method showed higher photocatalytic activity in the photocatalytic degradation of methylene blue (MB) under visible light irradiation. And the influences of hydrothermal temperature, calcined time, and sintering temperature on the photocatalytic performance of the SrFeO3-x prepared by the hydrothermal-citrate method were investigated.3. Typically, a photocatalytic reaction is conducted in a suspension of photocatalyst. Removal of such fine particles from large volumes of water presents a major drawback to the application of the photocatalytic processes in treating wastewater. The photocatalysts combined with magnetite made them be recycled easily from the treated water by magnetic force without complicated equipment and further processing. So the photocatalyst SrFeO3-x combined with magnetite SrFe12O19 with different composite ratio were prepared, and the magnetic properties and photocatalytic activities of as-prepared composite particles were evaluated. The results indicated that the increase of the SrFeO3-x shell content in the synthesized composite led to the decreased magnetization value and the increased photocatalytic activity. |
