In this study, preparation of 20mol% Si, 15mol% Zr and 5mol% Cu doped TiO2 nanopowders via sol–gel process have been investigated. The effects of Si, Zr and Cu doping and calcinations temperature (500–1,000 ◦C) on the structural, and photocatalytic properties of titania nanopowders studied by X-ray diffraction (XRD), scanning electron microscope (SEM-EDX), transmission electron microscope and UV–Vis absorption spectroscope. XRD patterns showed peak of the cristobalite phase at temperature 900 and 1,000 ◦C. Also, XRD results suggest that adding dopants has a significant effect on anatase phase stability, crystallinity, and particle size ofTiO2.Titania rutile phase formation in system (Ti–Si–Zr–Cu)was inhibited by Zr+4 and Si+4 at temperature 500–700 ◦C and promoted by Cu+2 doped TiO2 in high temperatures (800–1,000 ◦C), so that 41 and 15% anatase composition is retained even after calcination at 800, 900 ◦C respectively. The photocatalytic activity was evaluated by photocatalytic degradation kinetics of aqueous methyl orange (MO) under visible radiation. The degradation efficiency of MO reaches 85% of the doped samples after 40min of visible light irradiation at temperature 700 ◦C.
