Surface Modification of Porous Silica with the Liquid Phase Deposition Process Using Solid Materials for Fluorine Scavenger

TiO2-modified silica-based MCM-41 (Si-MCM-41) was prepared by liquid phase deposition (LPD) without a conventional fluorine scavenger such as H3BO3. TiO2 was deposited on Si-MCM-41 by LPD reactions for 1–48 h. Using Si-MCM-41, TiO2 was deposited on the inner surface of silica with etching phenomena. After the LPD reactions, Si species were detected in the reaction solution as a result of etching phenomena of silica. It was confirmed that Si-MCM-41 also acted as a fluorine scavenger by dissolving and forming hexafluorosilicate in aqueous hexafluorotitanate solution. The deposition behavior was greatly influenced by the volume of the reaction solution. The photocatalytic activity of the modified Si-MCM-41 was much higher than that of conventional catalysts such as TiO2:P25.