Synthesis and characterization of TiO2-coated SiO2 particles by hydrolysis of titanium alkoxide in alcohol solvents

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TiO2-coated SiO2 particles were prepared using industrially-wasted amorphous SiO2 particles by an alkoxide method. The amorphous SiO2 particles were used as support for TiO2 photocatalyst. The mean size of the amorphous SiO2 particle was approximately 100 nm. The major synthesis parameters were a kind of alcohol solvent (methanol, ethanol, and 1-propanol) and calcination temperature. The SiO2 particles and titanium tetraisopropoxide were mixed in an alcohol solvent and an appropriate amount of distilled water was added to the suspension for hydrolysis of the alkoxide. The precipitate was calcined in the temperature range from 600 to 1300°C to crystallize the deposited TiO2. The samples were characterized using XRD, BET and TEM-EDS analyzer. It was found that the use of SiO2 support, methanol solvent in hydrolysis of Ti alkoxide and freeze-drying of product were effective to keep the anatase phase at high calcination temperature even though the crystallite size of anatase increased and the specific surface area decreased. As a result, the maximum decomposition ratio of methylene blue was obtained on the TiO2-coated SiO2 particles synthesized in methanol solution and calcined at 1000°C.