The Synthesis of Eu3+Doped with TiO2Nano-Powder and Application as a Pesticide Sensor

Abstract

Using tetrabutyl titanate as precursor, <TEX>$Eu^{3+}$</TEX> doped <TEX>$TiO_2$</TEX> nano-powder was prepared by sol-gel method, the nature of luminescence of nano-powder was studied. The interaction of chlorpyrifos with <TEX>$Eu^{3+}$</TEX> doped <TEX>$TiO_2$</TEX> was studied by absorption and fluorescence spectroscopy. The results indicated the fluorescence intensity of <TEX>$Eu^{3+}$</TEX> doped <TEX>$TiO_2$</TEX> was quenched by chlorpyrifos and the quenching rate constant (<TEX>$k_q$</TEX>) was <TEX>$1.24{\times}10^{11}\;L/mol{\cdot}s$</TEX> according to the Stern-Volmer equation. The dynamics of photoinduced electron transfer from chlorpyrifos to conduction band of <TEX>$TiO_2$</TEX> nanoparticle was observed and the mechanism of electron transfer had been confirmed by the calculation of free energy change (<TEX>${\Delta}G_{et}$</TEX>) by applying Rehm-Weller equation as well as energy level diagram. A new rapid method for detection of chlorpyrifos was established according to the fluorescence intensity of <TEX>$Eu^{3+}$</TEX> doped <TEX>$TiO_2$</TEX> was proportional to chlorpyrifos concentration. The range of detection was <TEX>$5.0{\times}10^{-10}-2.5{\times}10^{-7}mol/L$</TEX> and the election limit (<TEX>$3{\sigma}$</TEX>) was <TEX>$3.2{\times}10^{-11}$</TEX> mol/L.