Smart Mn 7+ Sensing via Quenching on Dual Fluorescence of Eu 3+ Complex-Modified TiO 2 Nanoparticles.

In this work, titania (TiO 2 ) nanoparticles modified by Eu(TTA) 3 Phen complexes (ETP) were prepared by a simple solvothermal method developing a fluorescence Mn 7+ pollutant sensing system. The characterization results indicate that the ETP cause structural deformation and redshifts of the UV-visible light absorptions of host TiO 2 nanoparticles. The ETP also reduce the crystallinity and crystallite size of TiO 2 nanoparticles. Compared with TiO 2 nanoparticles modified with Eu 3+ (TiO 2 -Eu 3+ ), TiO 2 nanoparticles modified with ETP (TiO 2 -ETP) exhibit significantly stronger photoluminescence under the excitation of 394 nm. Under UV excitation, TiO 2 -ETP nanoparticles showed blue and red emission corresponding to TiO 2 and Eu 3+ . In addition, as the concentration of ETP in TiO 2 nanoparticles increases, the PL intensity at 612 nm also increases. When ETP-modified TiO 2 nanoparticles are added to an aqueous solution containing Mn 7+ , the fluorescence intensity of both TiO 2 and ETP decreases. The evolution of the fluorescence intensity ratio (I 1 /I 2 ) of TiO 2 and ETP is linearly related to the concentration of Mn 7+ . The sensitivity of fluorescence intensity to Mn 7+ 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.