Synthesis of polyaniline-modified Fe3O4 /SiO2 /TiO2 composite microspheres and their photocatalytic application

School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, PR China
Materials Letters (Impact Factor: 2.49). 06/2011; 65(19-20):2887-2890. DOI: 10.1016/j.matlet.2011.06.005


Polyaniline-modified Fe3O4 /SiO2 /TiO2 composite microspheres have been successfully synthesized by sol–gel reactions on Fe3O4 microspheres followed by the chemical oxidative polymerization of aniline. The synthesized multilayer-structured composites were characterized by TEM, XRD, TGA, UV–vis diffuse reflectance spectra and magnetometer. The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible light. The effect of polyaniline (PANI) amounts on the photocatalytic activity was investigated. The photocatalytic activity results show that the Fe3O4/SiO2/TiO2 composites with about 2.4 wt.%–4.1 wt.% PANI could show higher photocatalytic efficiency than that of Fe3O4/SiO2/TiO2 . Furthermore, the PANI-Fe3O4/SiO2/TiO2 photocatalyst could be easily recovered using a magnet.

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    • "Sol-gel method for mesoporous silica-titania composite is also reported byShao et al. [2]with TiOCl solution and sodium silicate as precursor in the absence of CTAB surfactant. Meanwhile, Nichi et al.[16]used sol-gel preparation of nanoscale TiO2/SiO2 composite and Huang et al.[17]also used sol-gel method on the synthesis of polyaniline-modified Fe2O3/SiO2/TiO2 composite. A sol-gel route also applied byWang et al. [18]to prepare a polyimide/silica/titania nanohybrids . "
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    • "Also, 80% degradation in 120 min [18], 92% degradation in 120 min [44], 80% degradation in 90 min [45] were achieved by using chemically synthesized PANI/TiO 2 composites. In another study, PANI produced by chemical polymerization in the presence of Fe 3 O 4 /SiO 2 /TiO 2 microsphere, resulted in 45% degradation in 325 min [46]. Only 16% degradation in 6 h was reached in a study in which the SnO x thin films used as photocatalyst [42]. "
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    ABSTRACT: In the present study, Fe3O4@SiO2 core–shell microspheres were prepared via two steps. First, Fe3O4 nanoparticles were synthesized by co-precipitation of Fe+3 and Fe+2 as reaction substrates and NaOH as precipitant. Second, the surface of Fe3O4 was coated with silica by hydrolysis of tetraethylorthosilicate as the silica source. Subsequently, in order to reduce the amount of interaction and the agglomeration of Fe3O4@SiO2 microspheres, the silica shell of these particles was modified by vinyltriethoxysilane as the silane coupling agent. The structural properties of the samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy analyses. The results indicated that the average sizes of Fe3O4 and Fe3O4@SiO2 particles were about 50 and 500 nm, respectively. Also, the surface characterization of Fe3O4@SiO2 microspheres showed that the silane coupling agent was covalently coupled with the silica surface.
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