Luminescent Rare Earth Ions Doped Materials For Environmental Applications

Contaminant detection and degradation are two important aspects in researching and mitigating environmental pollution.The development of convenient pollutant detection and efficient degradation technologies becomes research hotspots.In recent years,light-responsive pollutant detection and degradation technologies have attracted much attention because of their low cost and environmental friendliness.Especially for lanthanide luminescent materials,due to the unique and stable optical properties of lanthanide ions,it has broad application prospects in light sensing,biomarking and photocatalysis.This essay designs environmentally functional materials based on lanthanide luminescent ions for the visual detection and degradation of environmental pollutants,the main contents are as follows:(1)A series of mixed-crystal lanthanide metal-organic frameworks(MLMOFs)were synthesized by microwave method.In the spectrum of MLMOFs-2,the two characteristic peaks of Tb3+(547 nm)and Eu3+(619 nm)were comparable,thereby it was selected as the sensor for detecting pesticides in the water.The different changes of emission intensity ratio of Tb3+(5D4?7F5,547 nm)to Eu3+(5D0?7F2,619 nm)transitions depending on the guest molecules,which enable MLMOFs-2 to realize visual recognition of diverse pesticides.Moreover,in the concentration of 0.1?1 mmoL/L,the intensity ratio was observed to linearly correlate to the concentration of pretilachlor,lmazethapyr and myclobutanil,with the detection limit of 0.07 mmoL/L.Compared to the traditional detection method,which was based on absolute emission intensity of single lanthanide ion,MLMOFs generated more accurate luminescent signals,which was an excellent candidate of self-calibrating sensor.(2)The nanocomposites NaGdF4:Yb,Tm@NaGdF4@TiO2 has been successfully fabricated by a simply hydrothermal method.The near-infrared-driven photocatalyst was characterized by fluorescence spectrometer,scanning electron microscopy and X-ray diffraction.It is found that NaGdF4:Yb,Tm@NaGdF4@TiO2 consists of uniform hexagonal phase NaGdF4:Yb,Tm@NaGdF4 nanoparticles and anatase TiO2.As a model pollutant,Rhodamine B(Rh B)was used to investigate the photocatalytic activity of photocatalyst under 980 nm laser(3 W)excitation.Results indicated that 97%Rh B degraded in 5 h by using NaGdF4:Yb,Tm@NaGdF4@TiO2 as the photocatalyst.It was four times faster than traditional composites photocatalyst NaYF4:Yb,Tm@NaYF4@TiO2,which confirms that NaGdF4:Yb,Tm@NaGdF4@TiO2 is a more efficient near-infrared light response photocatalyst.