Preparation Of Transition Metal Sulfide Composite And Their Application In Fluorescence Sensing

With the development and progress of society,water quality protection and life and health have attracted more and more attention,and many new materials and technologies have been developed to detect pollutants in water quality.Fluorescence sensing technology stands out among many sensing technologies with its advantages of simple operation,high sensitivity and strong selectivity.Compared with traditional luminescent materials,transition metal sulfide composite materials have excellent luminescence characteristics,biocompatibility and high stability,and are widely used in the field of chemical sensing.In the paper,four highly sensitive and highly selective fluorescent probes were prepared based on transition metal sulfides,and the quantitative detection of heavy metal ions and common antibiotic in water quality was achieved with the help of fluorescent sensing technology.The specific content can be divided into the following four sections:1.A novel fluorescent probe based on Ag₂S QDs/g-C₃N₄ composite was synthesized by loading Ag₂S quantum dots（Ag₂S QDs）on the surface of g-C₃N₄ through in-situ synthesis method and developed to detect Nitrofurazone（NFZ）sensitively.The results showed that the linear detection range of Ag₂S QDs/g-C₃N₄to NFZ was 0.2-30μM,with the low detection limit of 0.054μM.Combining time-fluorescence-resolved spectroscopy,UV-vis absorption spectroscopy and theoretical calculations,we proposed the sensing mechanism of the formation of non-fluorescent ground state complex linked by hydrogen bonds.This work indicated that the Ag₂S QDs/g-C₃N₄composite processed the ability to detect NFZ efficiently and sensitively.2.L-cysteine modified ZnS nanoparticles（L-ZnS NPs）were constructed for highly sensitive and selective detection of copper ions(Cu²⁺).The results showed that after modification with L-cysteine,the fluorescence performance of ZnS was significantly increased,and the fluorescence quenching detection of the target was achieved by forming a complex with Cu²⁺.Under the optimal experimental conditions,L-ZnS exhibited a good linear relationship within the range of 3.5-25.5μM（R²=0.9983）,and the LOD was 7.28 n M.The method was applied to the detection of real samples,and the recovery rate of standard addition was 96.5%-101.6%.3.Cu²⁺doped ZnS microspheres（Zn CuS）was synthesized by a one-step hydrothermal method,and a fluorescent sensing platform for the detection of tetracycline hydrochloride（TC）was constructed.Under the optimal experimental conditions,the proposed"fluorescence quenching method"can detect TC as low as 1.48μM in the concentration range of 4.5-360μM.Time-resolved fluorescence spectroscopy and UV-vis absorption spectroscopy confirmed that Zn CuS can response to TC through the internal filtration effect（IFE）.In addition,the analytical method had excellent selectivity,reproducibility and applicability in actual water samples,providing a new way for the low limit detection of TC in water samples.4.The novel fluorescent probe based on Mn²⁺-doped CuS nanoflower（CuMnS）was successfully constructed and used for the detection of oxytetracycline hydrochloride（OTC）.The experiments results showed that the detection of OTC based on CuMnS sensor had a wide linear detection range（15-200μM）and a low detection limit（1.17μM）,and a satisfactory recovery rate was obtained in the actual water sample detection.In addition,the possible sensing mechanism between the probe and OTC was discussed through time-fluorescence-resolved spectroscopy and UV-vis absorption spectroscopy.