TiO2 nanopowders doped by Cu were prepared by sol–gel method. The effects of Cu 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 system (Ti–Cu) was promoted by Cu2+ doped TiO2. The photo-catalytic activity was evaluated by photo-catalytic degradation kinetics of aqueous methylene orange (MO) under visible radiation. The results show that the photo-catalytic activity of the 5 %Cu doped TiO2 nanopowders have a larger degradation efficiency than pure TiO2 under visible light. Also, The minimum band gap was estimated to be ∼ 1.9–2 eV from UV–Vis spectra.
