Synthesis,Characterization And Application Of Molybdenum Disulfide Quantum Dots

Transition metal chalcogenides(TMCs),especially molybdenum disulfide(MoS2),have recently attracted wide attention as graphene-analogous materials.However,few literatures have reported the synthesis of photoluminescent MoS2 materials and their applications in analytical chemistry.In this paper,two types of MoS2 QDs with different fluorescence characteristics were synthesized.Then fluorescence sensor was constructed based on them and glucose was successfully detected by the sensor.Finally,a study on the interaction between MoS2 QDs and BSA was conducted.This dissertation includes the following aspects:1.Synthesis and characterization of MoS2 QDsTwo kinds of MoS2 QDs were synthesized using sodium molybdate,L-cysteine,ammonium molybdate,N-acetyl-L-cysteine and thiourea as precursors by hydrothermal method.The MoS2 QDs were characterized by FT-IR spectroscopy,UV-vis spectroscopy,transmission electron microscopy(TEM),atomic force microscopy(AFM),energy duspersive spectrometer(EDS),X-ray photoelectron spectroscopy(XPS)and fluorescence spectroscopy(FL).The results showed that after a 36 h of reaction,the synthesized MoS2 QDs were monodispersed,with small sizes,good water solubility,excellent luminescence properties and high resistance to photobleaching;while the product with a reaction time of 4h had quenching ability.Therefore,the as-prepared MoS2 QDs have application potential in the field of analytical chemistry.2.Detection of glucose based on the sensor constructed by MoS2 QDs with photoluminescence and quenching propertiesAccording to the reported hydrothermal method,MoS2 QD4 with a quantum yield of 6.45%and MoS2 QD8 with quenching ability were synthesized respectively and used to construct the sensor for the detection of H2o2.MoS2 QD4 can be quenched by MoS2 QDg.After H2O2 was added to the sensor system,the fluorescence value of MoS2 QD4 was recovered.In fact,H2O2 can be produced during the enzymatic reaction between GOD and glucose.Therefore,glucose can be detected.Under the optimal conditions,a linear relationship between the relative fluorescence intensity(F-F0)/F0 and glucose concentration was obtained in a range from 10-700 μM with a detection limit of 1.0 μM.This method has been successfully applied to the determination of glucose in human serum.In conclusion,MoS2 QDs have potential application value in the field of analysis.3.Research of the interaction between MoS2 QDs and BSAIn this part,the effects of different conditions on the fluorescence intensity of MoS2 QDs were studied,including buffer system,pH,concentration of MoS2 QD4,sample sequence and reaction time.The interaction between MoS2 QD4 and BSA were investigated by using fluorescence spectrum,UV-vis absorption spectrum and circular dichroism spectrum.The results showed that the fluorescence intensity of MoS2 QD4 was enhanced with the increase of BSA.Moreover,the secondary structure of BSA was not be broken down by MoS2 QD4.However the intensities of circular dichroism and ultraviolet absorption of BSA were enhanced.These phenomena confirm that the interaction between MoS2 QD4 and BSA exists,which provides the possibility for MoS2 QDs as a fluorescent label.