Effects of metal doping (Cu, Ag, Eu) on the electronic and optical behavior of nanostructured TiO2

The effects of metal doping (M = Cu, Ag and Eu) were investigated in nanostructured (M-TiO2) with the objectives to define the location of metal ions in the host matrices, identifying their stable valence states and environments as well as the incidence on the structural, electronic and optical properties of M-TiO2. Sol-gel method was used for the synthesis based on the reactants as metal-acetate and titanium alkoxide with defined experimental conditions to achieve the formation of nanostructured anatase phase with metallic doping ratios about 1, 2 and 3 mol.%. The investigations of doped structures were carried out by using x-ray diffraction, Raman spectroscopy, UV–Vis absorption and electron paramagnetic resonance (EPR) which contributes to precise insights on the metal behavior in M-TiO2. Correlations of the metal states such as the stable valence and local environments were made with the crystalline domains sizes, stability of anatase phase, electrical conductivity and optical features of the different M-TiO2 samples. The photocatalytic activity of 3 mol.% doped structures was compared through a heterogeneous photocatalysis carried out for the degradation of organic dyes in solutions under Xe-source irradiation. The efficiency of this process was discussed as function of the doping peculiarities. Metal doping of TiO2 by Cu, Ag and Eu leads to the formation of different configurations for the metal environments as function of the metallic element and contribute to modulate the photoinduced electronic and optical responses of the doped structures. [Display omitted] •The work reports a consistent analysis on the physical features of metal doped TiO2 by using Cu, Ag and Eu devoted to realize efficient photocatalysts.