Simple Route to Monodispersed Silica−Titania Core−Shell Photocatalysts

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• 作者：Suo Hon Lim ; Nopphawan Phonthammachai ; Stevin S. Pramana ; T. J. White
• 刊名：Langmuir
• 出版年：2008
• 出版时间：June 17, 2008
• 年：2008
• 卷：24
• 期：12
• 页码：6226 - 6231
• 全文大小：2561K
• 年卷期：v.24,no.12(June 17, 2008)
• ISSN：1520-5827

文摘

A monodispersed silica−titania core−shell photocatalyst was synthesized via a sol−gel route without the need of pH adjustment, cationic polyelectrolytes, or surfactants in a process where silica spheres were impregnated with hydrolyzed titanium tetrabutoxide, incubated at room temperature, and then condensed using an ethanol/water (1:1) solvent. Four coating cycles in a 10% v/v titania sol produced homogeneous titania shells. The quality of catalysts was assessed quantitatively using Rietveld analysis of powder X-ray diffraction patterns combined with X-ray fluorescence spectrometry. During calcination, the anatase-to-rutile transformation was delayed to 1000 °C, which is ~300 °C higher than usually observed. The thermal stability and surface area of titania were enhanced through the slow crystal growth of anatase. The photocatalytic activity of the core−shell photocatalysts calcined at 400−600 °C was found to be proportional to the thickness of titania but did not directly correlate with the surface area.