Abstract: A series of TiO₂-XSiO₂[X denotes the molar fraction(%) of silica in the mixed oxides] with different n(Ti)/n(Si) ratios was prepared with ammonia water as a hydrolysis catalyst.The photocatalysts prepared were characterized by XRD, thermal analysis, FTIR, UV-Vis and SPS.The characterization results of FTIR and UV-Vis spectra show that Ti atoms were gradually changed from octahedral coordination to tetrahedral coordination with the addition of silica, which is not beneficial for obtaining strong Brnsted acidity and higher photocatalytic activity.The photocatalytic activity experiments, which were conducted by using heptane(or SO₂) as the model reactant, showed that TiO₂-SiO₂ containing a suitable amount of silica can exhibit much higher photocatalytic activity than pure TiO₂.The enhanced photocatalytic activity can be attributed to three following factors: (1) smaller crystalline size; (2) higher thermal stability;(3) the new strong Brnsted acidity.

Key words: TiO₂-SiO₂ mixed oxide, Basic hydrolysis, Photocatalytic oxidation