Synthesis, characterization and photocatalytic properties of nanostructured lanthanide doped β-NaYF/TiO composite films.

The photocatalytic approach is known to be one of the most promising advanced oxidation processes for the tertiary treatment of polluted water. In this paper, β-NaYF/TiO composite films have been synthetized through a novel sol-gel/spin-coating approach using a mixture of β-diketonate complexes of Na and Y, and Yb, Tm, Gd, Eu as doping ions, together with the TiO P25 nanoparticles. The herein pioneering approach represents an easy, straightforward and industrially appealing method for the fabrication of doped β-NaYF/TiO composites. The effect of the doped β-NaYF phase on the photocatalytic activity of TiO for the degradation of methylene blue (MB) has been deeply investigated. In particular, the upconverting TiO/β-NaYF: 20%Yb, 2% Gd, x% Tm (x = 0.5 and 1%) and the downshifting TiO/β-NaYF: 10% Eu composite films have been tested on MB degradation both under UV and visible light irradiation. An improvement up to 42.4% in the degradation of MB has been observed for the TiO/β-NaYF: 10% Eu system after 240 min of UV irradiation.