Study on Microstructure and Photocatalytic Activity of TiO₂ with Surface Modification by SiO₂ and Al₂O₃

Sodium silicate and sodium metaaluminate were used for the inorganic surface modification of TiO₂ matrix to block the electron-hole produced by light irradiation on TiO₂,finally attempting to improve the weatherability and dispersity of TiO₂.The growth of membrane layer on the surface of TiO₂ particles was tested online by focused beam reflectance measurement(FBRM).The phase composition and micro/nano structure of TiO₂ before and after modification were characterized and analyzed by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscope(SEM),transmission electron microscope(TEM) and specific surface area test(BET),respectively.The results show that a uniform and compact amorphous SiO₂ and stable boehmite colloid membrane layer have been formed on the surface of TiO₂ particles,which can fill the oxygen vacancies and make up the defects of photochemical activity for TiO₂.It is also indicated through the test of photodegradation that the photocatalytic activity of TiO₂ samples respectively with single silicon and silicon-aluminum binary modifications decrease with slower degradation rates,proving that TiO₂ has gotten effective protection.