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Preparation and Photocatalytic Activity of Magnetic Fe3O4/SiO2/TiO2 Composites

DOI: 10.1155/2012/409379

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A simple sol-gel method was used to prepare magnetic Fe3O4/SiO2/TiO2 composites with core-shell structure. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) have been applied to investigate the structure and morphology of the resultant composites. The obtained composites showed excellent magnetism and higher photodegradation ability than pure TiO2. The photocatalytic mechanism was also discussed. The magnetic composites should be extended to various potential applications, such as photodegradation, catalysis, separation, and purification processes. 1. Introduction Currently, there has been great interest in the preparation of core-shell micro- and nanoparticles for their widespread potential applications in catalysis, chromatography separation, drug delivery, chemical reactors, and protection of environmentally sensitive materials [1–4]. Heterogeneous photocatalysis using semiconducting oxide catalysts is an effective way to purify wastewater or gas. TiO2-based semiconductors have attracted considerable attention due to their high efficiency, good stability, availability, and nontoxicity [5–9]. In recent years, in order to enhance the photocatalytic activity, great efforts have been made to prepare ideal structure of TiO2-based semiconductors [10–12]. Magnetic separation provides a very convenient approach for removing and recycling magnetic composites by applying an added magnetic field. The incorporation of Fe3O4 magnetic particles into TiO2 matrix may block the aggregation of nanoparticles during renewal and can increase the durability of the catalysts [13, 14]. Moreover, such catalysts have a high surface area and well-defined pore size, which enhance their photocatalytic activity [15]. However, magnetic nanoparticles would inescapably encounter an hindrance when applied in practice due to the fact that a photocatalytic reaction is conducted in a suspension. It is not allowed to use magneton to agitate the mixed solutions. Therefore, in the experiment, Ar gas is purged so as to make the magnetic particles suspend in the methylene blue (MB) solution. Many efforts have been made in the development of the design and preparation of magnetic core-shell microspheres. Ye et al. and Yu et al. reported the magnetic material/SiO2/TiO2 composites with core-shell-shell structure [16, 17]. Their methods involve superparamagnetic Fe3O4 and γ-Fe2O3 with an inner layer of SiO2 and outer layer of TiO2 [18, 19]. Their resultant samples exhibit

References

[1]  F. Caruso, R. A. Caruso, and H. M?hwald, “Nanoengineering of inorganic and hybrid hollow spheres by colloidal templating,” Science, vol. 282, no. 5391, pp. 1111–1114, 1998.
[2]  R. A. Caruso, A. Susha, and F. Caruso, “Multilayered titania, silica, and Laponite nanoparticle coatings on polystyrene colloidal templates and resulting inorganic hollow spheres,” Chemistry of Materials, vol. 13, no. 2, pp. 400–409, 2001.
[3]  F. Caruso, X. Shi, R. A. Caruso, and A. Susha, “Hollow titania spheres from layered precursor deposition on sacrificial colloidal core particles,” Advanced Materials, vol. 13, no. 10, pp. 740–744, 2001.
[4]  G. Li, Q. Shi, S. J. Yuan, K. G. Neoh, E. T. Kang, and X. Yang, “Alternating silica/polymer multilayer hybrid microspheres templates for double-shelled polymer and inorganic hollow microstructures,” Chemistry of Materials, vol. 22, no. 4, pp. 1309–1317, 2010.
[5]  J. M. Herrmann, “Heterogeneous photocatalysis: fundamentals and applications to the removal of various types of aqueous pollutants,” Catalysis Today, vol. 53, no. 1, pp. 115–129, 1999.
[6]  Z. Xu and J. Yu, “Visible-light-induced photoelectrochemical behaviors of Fe-modified TiO2 nanotube arrays,” Nanoscale, vol. 3, no. 8, pp. 3138–3144, 2011.
[7]  H. Li, Z. Bian, J. Zhu, Y. Huo, H. Li, and Y. Lu, “Mesoporous Au/TiO2 nanocomposites with enhanced photocatalytic activity,” Journal of the American Chemical Society, vol. 129, no. 15, pp. 4538–4539, 2007.
[8]  H. Q. Wang, Z. B. Wu, and Y. Liu, “A simple two-step template approach for preparing carbon-doped mesoporous TiO2 hollow microspheres,” Journal of Physical Chemistry C, vol. 113, no. 30, pp. 13317–13324, 2009.
[9]  X. Chen and S. S. Mao, “Titanium dioxide nanomaterials: synthesis, properties, modifications and applications,” Chemical Reviews, vol. 107, no. 7, pp. 2891–2959, 2007.
[10]  J. C. Lee, T. G. Kim, W. Lee, S. H. Han, and Y. M. Sung, “Growth of CdS nanorod-coated TiO2 nanowires on conductive glass for photovoltaic applications,” Crystal Growth and Design, vol. 9, no. 10, pp. 4519–4523, 2009.
[11]  R. A. Lucky, R. Sui, J. M. H. Lo, and P. A. Charpentier, “Effect of solvent on the crystal growth of one-dimensional ZrO2·TiO2 nanostructures,” Crystal Growth and Design, vol. 10, no. 4, pp. 1598–1604, 2010.
[12]  S. Xuan, W. Jiang, X. Gong, Y. Hu, and Z. Chen, “Magnetically separable Fe3O4/TiO2 hollow spheres: fabrication and photocatalytic activity,” Journal of Physical Chemistry C, vol. 113, no. 2, pp. 553–558, 2009.
[13]  W. Cheng, K. Tang, Y. Qi, J. Sheng, and Z. Liu, “One-step synthesis of superparamagnetic monodisperse porous Fe3O4 hollow and core-shell spheres,” Journal of Materials Chemistry, vol. 20, no. 9, pp. 1799–1805, 2010.
[14]  Z. Liu, H. Bai, and D. D. Sun, “Facile fabrication of porous chitosan/TiO2/Fe3O4 microspheres with multifunction for water purifications,” New Journal of Chemistry, vol. 35, no. 1, pp. 137–140, 2011.
[15]  M. Shokouhimehr, Y. Piao, J. Kim, Y. Jang, and T. Hyeon, “A magnetically recyclable nanocomposite catalyst for olefin epoxidation,” Angewandte Chemie—International Edition, vol. 46, no. 37, pp. 7039–7043, 2007.
[16]  M. M. Ye, Q. Zhang, Y. X. Hu, et al., “Magnetically recoverable core-shell nanocomposites with enhanced photocatalytic activity,” Chemistry—A European Journal, vol. 16, no. 21, pp. 6243–6250, 2010.
[17]  X. Yu, S. Liu, and J. Yu, “Superparamagnetic γ-Fe2O3/SiO2/TiO2 composite microspheres with superior photocatalytic properties,” Applied Catalysis B, vol. 104, no. 1-2, pp. 12–20, 2011.
[18]  W. St?ber, A. Fink, and E. Bohn, “Controlled growth of monodisperse silica spheres in the micron size range,” Journal of Colloid And Interface Science, vol. 26, no. 1, pp. 62–69, 1968.
[19]  J. W. Lee, M. R. Othman, Y. Eom, T. G. Lee, W. S. Kim, and J. Kim, “The effects of sonification and TiO2 deposition on the micro-characteristics of the thermally treated SiO2/TiO2 spherical core-shell particles for photo-catalysis of methyl orange,” Microporous and Mesoporous Materials, vol. 116, no. 1-3, pp. 561–568, 2008.
[20]  J. Zhou, L. Meng, Q. Lu, J. Fu, and X. Huang, “Superparamagnetic submicro-megranates: Fe3O4 nanoparticles coated with highly cross-linked organic/inorganic hybrids,” Chemical Communications, no. 42, pp. 6370–6372, 2009.
[21]  C. Hui, C. Shen, J. Tian et al., “Core-shell Fe3O4/SiO2 nanoparticles synthesized with well-dispersed hydrophilic Fe3O4 seeds,” Nanoscale, vol. 3, no. 2, pp. 701–705, 2011.
[22]  Y. Chen, K. Wang, and L. Lou, “Photodegradation of dye pollutants on silica gel supported TiO2 particles under visible light irradiation,” Journal of Photochemistry and Photobiology A, vol. 163, no. 1-2, pp. 281–287, 2004.
[23]  G. Jiang, X. Zheng, Y. Wang, T. Li, and X. Sun, “Photo-degradation of methylene blue by multi-walled carbon nanotubes/TiO2 composites,” Powder Technology, vol. 207, no. 1–3, pp. 465–469, 2011.
[24]  K. Y. Jung and S. B. Park, “Enhanced photoactivity of silica-embedded titania particles prepared by sol-gel process for the decomposition of trichloroethylene,” Applied Catalysis B, vol. 25, no. 4, pp. 249–256, 2000.
[25]  Z. Ding, G. Q. Lu, and P. F. Greenfield, “Role of the crystallite phase of TiO2 in heterogeneous photocatalysis for phenol oxidation in water,” Journal of Physical Chemistry B, vol. 104, no. 19, pp. 4815–4820, 2000.
[26]  Z. Liu, X. Quan, H. Fu, X. Li, and K. Yang, “Effect of embedded-silica on microstructure and photocatalytic activity of titania prepared by ultrasound-assisted hydrolysis,” Applied Catalysis B, vol. 52, no. 1, pp. 33–40, 2004.
[27]  J. Yu, X. Yu, B. Huang, X. Zhang, and Y. Dai, “Hydrothermal synthesis and visible-light photocatalytic activity of novel cage-like ferric oxide hollow spheres,” Crystal Growth and Design, vol. 9, no. 3, pp. 1474–1480, 2009.
[28]  J. Yu, L. Zhang, B. Cheng, and Y. Su, “Hydrothermal preparation and photocatalytic activity of hierarchically sponge-like macro-/mesoporous Titania,” Journal of Physical Chemistry C, vol. 111, no. 28, pp. 10582–10589, 2007.
[29]  G. Jiang, R. Wang, H. Jin et al., “Preparation of Cu2O/TiO2 composite porous carbon microspheres as efficient visible light-responsive photocatalysts,” Powder Technology, vol. 212, no. 1, pp. 284–288, 2011.
[30]  R. J. Wang, G. H. Jiang, Y. W. Ding, et al., “Photocatalytic activity of heterostructures based on TiO2 and halloysite nanotubes,” ACS Applied Materials and Interfaces, vol. 3, no. 10, pp. 4154–4158, 2011.
[31]  L. Cao, S. Sahu, P. Anilkumar et al., “Carbon nanoparticles as visible-light photocatalysts for efficient CO2 conversion and beyond,” Journal of the American Chemical Society, vol. 133, no. 13, pp. 4754–4757, 2011.
[32]  Q. Xiang, J. Yu, and P. K. Wong, “Quantitative characterization of hydroxyl radicals produced by various photocatalysts,” Journal of Colloid and Interface Science, vol. 357, no. 1, pp. 163–167, 2011.

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