Study On The Preparation And Application Of Au/WS₂ Quantum Dot Composite

Quantum dots?QDs?possess excellent potential application in light,electricity,magnetism,and catalysis with their satisfactory luminescence properties.Zero-dimensional WS₂ quantum dots exhibit ultra-high tunability due to quantum confinement and size effects,and they are widely used in many aspects such as electroluminescence,optical switches,solar cells and biometric imaging.There are mainly two mechanical methods,including the"top-down"and"bottom-up"methods,to obtain low-dimensional semiconductor WS₂ QDs.Since their size and quantum yield is not easy to control by the conventional methods,the prepared WS₂ QDs can't meet our expectations.The complex nanostructures modified by Au nanoparticles?AuNPs?have attracted more and more attention because of their unique optical and electronic properties stimulated from special heterojunction and exciton proton coupling.In recent years,AuNPs-based composite nanomaterials have attracted great attention.In this paper,WS₂ QDs were synthesized by hydrothermal method,and then the Au/WS₂ quantum dot nanocomposites?Au/WS₂ QCs?were prepared by in situ reduction method.On the basis of the unique properties of WS₂ QDs and nano Au,by combining the superior performance and synergistic catalysis of WS₂ QDs with nano Au,the peroxidase activity and its enzymatic catalysis for H₂O₂ were investigated.The applications of Au/WS₂ QCs in the detection of real samples were also explored.The main contents of this thesis are as follows:Chapter 1:Synthesis and characterization of Au/WS₂ QCsIn this paper,a novel water-soluble WS₂ QDs was synthesized by simple hydrothermal method,and Au/WS₂ QCs were prepared by in situ reduction method combined with the advantages of AuNPs.The morphology,structure,composition and valence of Au/WS₂ QCs were characterized,and the optimum synthesis time and the ratio of each component were investigated.The synthesis method of composite materials is low cost,environmentally friendly and simple.This work not only provides an extension method to prepare other transition metal compounds,but also provides a good foundation for the application of Au/WS₂ QCs in environmental chemistry and biomedicine.Chapter 2:Study on the peroxidase properties of Au/WS₂ QCsIn the first chapter,the peroxidase-like activity of the prepapred ultrasmall Au/WS₂ QCs was studied using Au/WS₂ QCs as the research object,TMB as chromogenic substrate,and the synergetic effect of AuNPs and WS₂ QDs was invetigated.Based on their excellent peroxidase-like activity,the Au/WS₂ QCs were successfully applied to labele free,highly selective and sensitive colorimetric detection of H₂O₂ and glucose.The linear range of H₂O₂ was 2?mol/L-1.8 mmol/L,and the detection limit was 0.676?mol/L?S/N=3?under the optimum reaction conditions.The linear range of the glucose detection was 0.02 mmol/L-1.2 mmol/L,the detection limit was 0.879?mol/L?S/N=3?.Due to the above results,the as-prepared Au/WS₂ QCs would play a great potential role in environmental chemistry,biotechnology and clinical diagnosis.Chapter 3:Electrochemical sensors based on Au/WS₂ QCs for detection of H₂O₂released by cellsBased on the good peroxidase-like activity of Au/WS₂ QCs,a novel non-enzymatic amperometric sensor for H₂O₂ was further constructed.The results showd that Au/WS₂ QCs modified electrode possessed good catalytic effect for H₂O₂detection.Under the optimum conditions,the linear range of H₂O₂ detected by Au/WS₂ QCs was 0.05?mol/L³7.6656 mmol/L,and the detection limit was 0.0185?mol/L?S/N=3?.Therefore,Au/WS₂ QCs provided a promising platform for studying the electrocatalytic performance of quantum dot composites for high sensitivity detection of H₂O₂.In addition,because of its good electrocatalytic activity,easy preparation,good stability and selectivity,the sensor was successfully achieved a highly sensitive,fast and accurate detection of H₂O₂ released by PC12 cells without enzyme.Therefore,the enzyme-free sensing platform constructed in this experiment can not only provide a good research basis for studying the performance of other quantum dot composites in electrocatalytic performance and a high sensitivity detection of H₂O₂ by electrochemical method,but also offer an excellent research platform for other fields,such as physiology and pathology study.