Synthesis And Photocatalytic Properties Of Fe₂O₃/Bi₂O₂CO₃ Nanocomposites

In recent years, bismuth oxide based materials, a novel kind of semiconductor, have been intensively studied due to its special layered structure and outstanding chemical and physical properties. Therefore, the application of bismuth oxide based materials is also very broad, such as solar cells, sensors, ferroelectric materials, nonlinear optical materials and optical catalysis. As a representative member of Aurivillius-related oxide materials, the Bi2O2CO3 is a typical “sillén” phase, in which(Bi2O2)2+ layers and(CO3)2- layers are alternately arranged with the plane of the(CO3)2-group orthogonal to the plane of the layer. The strong intrinsic electric field between the bismuth oxide layer and the carbon oxide layer can effectively promote the separation of photo-generated electron and hole pairs. So, the Bi2O2CO3 photocatalyst shows good photocatalytic activity. In this paper, Bi2O2CO3 photocatalyst has been synthesized by the simply modified hydrothermal method. Then, the effets of the several kinds of organic dyes on its photocatalytic properties have been systematically studied. Afterwards, Bi2O2CO3 has shown good photocatalytic performance in recent years. However, its band gap is relatively large. Therefore, we choose the visible light response Fe2O3 coupled with Bi2O2CO3 to enlarge the light absorb range. Fe2O3/Bi2O2CO3 composite catalyst with the different molar ratios was also synthesized by the facile one-step modified hydrothermal method. The main contents of this paper can be summarized as follows:Bi2O2CO3 photocatalyst has been synthesized by a simply modified hydrothermal method. The as-prepared sample was characterized by XRD, TG-DSC, SEM, TEM, XPS and UV-vis to evaluate the elements, structure, morphology, thermal stability and optical properties. Rhodamine B(Rh B), Methyl Orange(MO) and Methylene Blue(MB) were separately used as the model substance to evaluate the photocatalytic activity of the Bi2O2CO3 photocatalyst under the simulated sunlight. The results indicated that the pure Bi2O2CO3 exhibited much higher photocatalytic activity for degrading Rh B than the MO and MB. In 50 min, 50 m L Rhodamine B solution with the concentration about 2 × 10-5 M can be photodegraded completely.Here, visible light absorbing Fe2O3 semiconductor is chosen as sensitizer to modify wide band-gap Bi2O2CO3 semiconductor in order to enhance its photocatalytic properties by shifting the UV-driven catalytic activ-ity to visible-light-driven catalytic activity. The Fe2O3/Bi2O2CO3 nanosheets with exposed active {001} facet were fabricated by a facile one-step modified hydrothermal method. The as-prepared samples were characterized by XRD, TG-DSC, SEM, TEM, XPS and UV-vis to evaluate the elements, structure, morphology, thermal stability and optical properties. The photocatalytic activities of the Bi2O2CO3 and Fe2O3/Bi2O2CO3 with different molar ratio of Fe2O3 to Bi2O2CO3 were compared. It was found that the Fe2O3/Bi2O2CO3 catalyst displays greatly enhanced photocatalytic activity with respect to the Bi2O2CO3 catalyst. When the amount of Fe2O3 reached the optimal value(5 mol%), the photocatalytic activity of Fe2O3/Bi2O2CO3 is greatly enhanced and exceeds that of other samples. In 25 min, 50 m L Rhodamine B solution with the concentration about 2 × 10-5 M can be photodegraded completely. The photocatalyst shows good photostability and recyclability. A mixture of multi-colored dyes including Rhodamine-B, Methylene Blue and Methyl Orange can be completely degraded by the Fe2O3/Bi2O2CO3 catalyst(5 mol% Fe2O3) within 45 min under the simulated sunlight irradiation. The photocatalytic mechanism was discussed in detail.