Smart Mn Sensing via Quenching on Dual Fluorescence of Eu Complex-Modified TiO Nanoparticles.

In this work, titania (TiO) nanoparticles modified by Eu(TTA)Phen complexes (ETP) were prepared by a simple solvothermal method developing a fluorescence Mn pollutant sensing system. The characterization results indicate that the ETP cause structural deformation and redshifts of the UV-visible light absorptions of host TiO nanoparticles. The ETP also reduce the crystallinity and crystallite size of TiO nanoparticles. Compared with TiO nanoparticles modified with Eu (TiO-Eu), TiO nanoparticles modified with ETP (TiO-ETP) exhibit significantly stronger photoluminescence under the excitation of 394 nm. Under UV excitation, TiO-ETP nanoparticles showed blue and red emission corresponding to TiO and Eu. In addition, as the concentration of ETP in TiO nanoparticles increases, the PL intensity at 612 nm also increases. When ETP-modified TiO nanoparticles are added to an aqueous solution containing Mn, the fluorescence intensity of both TiO and ETP decreases. The evolution of the fluorescence intensity ratio (I/I) of TiO and ETP is linearly related to the concentration of Mn. The sensitivity of fluorescence intensity to Mn concentration enables the design of dual fluorescence ratio solid particle sensors. The method proposed here is simple, accurate, efficient, and not affected by the environmental conditions.