Preparation and Photocatalytic Properties of TiO 2 /SiO 2 Composite Nanofibers
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Preparation and Photocatalytic Properties of TiO2/SiO2 Composite Nanofibers Sung Wook Lee, Tae Ho Lim, Sang Beom Kim, and Dong Ho Hyun Center for Research and Development, Doobon Inc., Cheongwon-gun, 363-893, Korea, Republic of ABSTRACT (1-x)SiO2/(x)TiO2 composite micro/nano scale fibers with various compositions were successfully prepared by electrospinning their sol-gel precursors of titanium(IV) isopropoxide(TiP), and tetraethyl orthosilicate(TEOS), followed by calcinations. Any gelator or binder was not used in this direct preparation process for composite fibers. The surface morphology and structure of sintered composite fibers were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), highresolution transmission electron microscopy (HR-TEM), and Fourier transform infrared (FT-IR). The crystallization behavior and surface morphology of the as-spun fibers were largely influenced by the calcination temperature and the content of TiO2. The photocatalytic activity of SiO2/TiO2 composite fibers was examined by UV/VIS-DRS spectra. The experiments demonstrated that the MB in aqueous solution was successfully photodegraded using SiO2/TiO2 composite nanofibers under UV-visible light irradiation.
INTRODUCTION These one-dimensional structures have also been of interest for many applications including semiconductor industry. Among them, much effort has been concentrated to improve the surface area of inorganic materials which may has large effect of its properties. Nanostructured SiO2/TiO2 materials have widely been used as anti-reflecting coating, optical-chemical sensors, glasses, supporting materials, and catalysts because of their superior optical and thermal properties as well as chemical durability[1-6]. The electrospinning technique, which has been known since the 1930s, is a useful way to producing submicro-scale fibers through the action of an external electric field imposed on a polymeric liquid or solgel precursor solution. The morphologies and properties of nanofibers depend on the properties of materials and the electrospinning parameters, including the solution concentration, viscosity, applied electric field strength, and tip-to-collector distance (TCD). Recently, there are a number of studies related to the photocatalytic activity of metal oxide-TiO2 catalyst for the purpose of improving TiO2 –photocatalytic activity including CdS[7,8], SnO2 [9,10], WO3 [11], ZrO2[12], and SiO2 [13]. Coupled semiconductor photocatalytst may increase the efficiency of photocatalytic process by increasing the charge separation and extending the energy range of photoexcitation.
In the current study, the direct formation of silica/titania, (1-x)SiO2/(x)TiO2 composite nano/micro fibers using sol-gel method and electrospinning technique and their properties are presented. Hence, the silica/titania composite sol in the current study does not contain any gelator or binder to help spinnability and their photocatalytic activity by employing methylene blue(MB) was evaluated, which is widely
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