(618an) Low-Temperature Synthesis of Titanium Dioxide and Its Characterization

Crystalline titanium dioxide (TiO₂) powders have been prepared by the modified alkoxide method at low temperatures (45-180^OC). In the experiment, the influences of reaction temperature, pH value and type of acid catalyst on the formation of TiO₂ were systematically investigated. The resulting TiO₂ powders were characterized with the X-ray diffraction (XRD), specific surface area measurement, and Field Emission Scanning Electron Microscopy (FE-SEM). The photocatalytic activities of the resulting samples were also evaluated by photocatalytic decomposition of 2, 4-dinitrophenol (DNP). The result indicated that the obtained TiO₂ powders possessed high specific surface area which was about three times greater than commercial photocatalyst, Degussa P-25. The phase composition, morphology, and specific surface area of TiO₂ changed significantly, depending on the pH value, reaction temperature, type of acid catalyst in the preparation process. DNP decomposition experiments showed that photocatalytic activity was affected by the balance between specific surface area and crystallinity. As to the effect of acid catalyst on the DNP decomposition activity, the activity was in the order of: HCl > HNO₃ > no acid catalyst > H₂SO₄.