Photoluminescent, self-cleaning titanium oxide nanocomposites with multifunctional properties

Abstract

© The Royal Society of Chemistry 2014.Photoluminescent and self-cleaning properties of an Eu<sup>3+</sup> doped titania-silica-lanthanum phosphate nanocomposite (Eu-TSL) prepared by an aqueous sol-gel process and films fabricated on glass substrates by dip coating are investigated in the present work. These nanocomposites containing Eu<sup>3+</sup> as dopants exhibit red luminescence upon visible light excitation, after heat treatment at 400°C. For an excitation wavelength of 465 nm, the PL spectra of Eu-TSL show intense peaks at 613 nm (<sup>5</sup>D<inf>0</inf>-<sup>7</sup>F<inf>2</inf>), characteristic of Eu<sup>3+</sup> ions. This red emission has a life time of ~0.5 ms. 1 mol% Eu added TSL shows ~96% methylene blue dye degradation after two hours UV light exposure which is attributed to the presence of anatase phase, optimum crystallite size (5.7 nm) and enhanced specific surface area (147 m<sup>2</sup> g<sup>-1</sup>). Eu-TSL was found to be five times more efficient in decolourization of methylene blue than Eu-TiO<inf>2</inf> from the reported literature. Eu-TSL retains all the major properties including photoactivity, transparency (~97%) and low wettability (~80°). In addition, red emission could be integrated at very low europium doping levels (1 mol%). Even though europium doping on titania is reported widely, a multifunctional luminescent and self-cleaning composition based on Eu-TSL synthesized by an aqueous sol-gel route is reported for the first time.