Fabrication Of Fluorophore Molecules/layered Double Hydroxide Thin Films And Their Application In Sensors

In this thesis, the fabrication of fluorophores/LDH ultrathin films（UTFs） via layer-by-layer self-assembly technique has been carried out,and their ratiometric fluorescence response towards Be²⁺and Hg²⁺：wassuccessfully demonstrated, respectively. The UTFs can be potentiallyused as chemosensors in the environmental and biomedical field.The （Beryllon II/LDH）nUTFs were fabricated via alternate assemblyof Beryllon II and MgAl-LDH nanosheets on quartz substrates using thelayer-by-layer （LBL） deposition technique. Scanning electron microscopyshows a uniform and homogenous morphology for the Beryllon II/LDHfilms; X-ray diffraction indicates a periodic layered structureperpendicular to the substrate, in which Beryllon II molecules areaccomodated as double-layer arrangement in the LDH matrix. TheBeryllon II/LDH UTFs display ratiometric fluorescence response for Be²⁺with a linear response range in1.0×10^-71.9×10^-6mol L^–1and adetection limit of4.2×10^-9mol L^–1. Furthermore, the ratiometric sensor exhibits good repeatability, high stability （thermal, storage andmechanical） as well as excellent selectivity towards Be²⁺. XPS andRaman measurements demonstrate that the specific response of the sensoris attributed to the coordination between Be²⁺and Beryllon II in the UTF.The （Primuline/LDH）nUTFs were obtained via alternate assemblyof Primuline and LDH nanosheets on quartz substrates using thelayer-by-layer （LBL） deposition technique. SEM and X-ray diffractionindicate a superlattice structure with the ab-plane of LDH microcrystalsparallel to the substrate. Scanning electron microscopy shows a uniformand homogenous morphology for the Primuline/LDH UTFs. ThePrimuline/LDH UTFs display ratiometric fluorescence response towardsHg2+with a linear response range in2.5100nM and a detection limit of0.13pM. Furthermore, the ratiometric sensor exhibits good repeatability,high stability （storage and mechanical） as well as excellent selectivitytowards Hg²⁺. XPS measurements reveal that the coordination betweenHg²⁺and Primuline in the UTF leads to the specific response of thesensor.