Photoluminescent, self-cleaning titanium oxide nanocomposites with multifunctional properties
Photoluminescent and self-cleaning properties of an Eu3+ 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 Eu3+ 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 (5D0–7F2), characteristic of Eu3+ 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 m2 g−1). Eu-TSL was found to be five times more efficient in decolourization of methylene blue than Eu-TiO2 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.