SiO2 nanoparticles doped by 10 mol% Zr and 10 mol% Cu were prepared via the sol-gel method in a controled process. The effects of doping and calcination temperature on the structural and photo-catalytic properties of SiO2 nanopowders were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-Vis absorption spectroscopy. The phases of cristobalite, quartz and tridymite were found at a calcinations temperature range of 800 to 1000 ◦C and only cristobalite phase was formed at a temperature of 1200 ◦C. The degradation of methyl orange was examined under visible light radiation indicating that the effect of doped elements (Zr, Cu) on SiO2 reduces the band gap effectively.
