TiO2 nanopowders doped by Si and Zr were prepared by sol-gel method. The effects of Si and Zr doping on the structural, optical, and photo-catalytic properties of titania nanopowders have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis absorption spectroscopy. XRD results suggest that adding impurities has a significant effect on anatase phase stability, crystallinity, and particle size of TiO2. Titania rutile phase formation in ternary system (Ti-Si-Zr) was inhibited by Zr4+ and Si4+ co-doped TiO2 in high temperatures (500 0C–900 0C) and 36 mol% anatase composition is retained even after calcination at 1000 0C . The photocatalyst activity was evaluated by photocatalytic degradation kinetics of aqueous methylen orange (MO) under visible radiation. The results show that the photocatalytic activity of the 20%Si and 15%Zr co-doped TiO2 nanopowders have a larger degradation efficiency than pure TiO2 under visible light.
