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Shvoong Home>Science>Synthesis and Characterization of Metal-doped and Silylated TiO2-SiO2 Aerogels as Photocatalyst Summary

Synthesis and Characterization of Metal-doped and Silylated TiO2-SiO2 Aerogels as Photocatalyst

Article Summary   by:fadzlina     Original Authors: Tan Yin Yin; Mohd. Nazlan Mohd. Muhid; Lee Siew Ling
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Titania silica aerogels with various molar ratios of Ti:Si = 1:25, 1:33 and 1:50 were prepared by sol-gel method. The properties of the semiconductor were also modified by incorporating chromium into the titania silica aerogel with different amount (e.g. 1 wt%, 5 wt% and 10 wt%). Silylation reaction onto the synthesized aerogels was carried out in order to reduce the hydrophilicity of the aerogels. The samples were silylated using tertbutyldimetylchloro silane with molar ratio of SiO2:R = 0.2 (R = tertbutyldimethylchloro silane). All the samples prepared were characterized using XRD, FTIR, and UV-Vis DRS. XRD diffractograms showed no peak, which means all metal was well dispersed in the aerogel. FTIR results did not reveal any significant difference between the silica aerogel and titania silica aerogel due to the overlapping of Si-OH and Si-O-Ti bands at around 960 cm-1. However, two small peaks at 2965 and 2844 cm-1 were observed in the silylated samples typically appointed to the CH3 and CH2 stretchings indicating successful silylation of tertbutlydimethylchloro silane. The upper branch of absorptions in the UV-Vis DRS spectra practically coincides with that of titania exist in the aerogels. However, a weak absorption was found at 420 nm in Cr-doped silica titania aerogel. This is due to the charge transfer from O2- to Cr6+ of the tetrahedrally coordinated Cr-Oxide moieties chromium in the samples. As the amount of dopants increase, the intensity of the peak has become more intense. Photocatalytic testing has been carried out on synthesized titania silica aerogel with molar ratio Ti:Si = 1:33 and 5 wt% Cr-doped titania silica aerogel samples. Cr-doped titania silica sample make up a better conversion value than that of titania silica aerogel. The electron scavenger property possessed by the metal helps to inhibit the recombination rate between the electron hole pairs.
Published: April 27, 2007   
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