Research On The Preparation Of Silver Sulfide Nanocomposite And Its Application In The Field Of Sensors

In order to overcome the shortcomings of some single-component inorganic semiconductor materials,such as easy recombination of electron-hole pairs,low photoelectric conversion efficiency and poor electrochemical performance synergy.The thesis is based on the study of the mutual recombination of inorganic semiconductor materials,thereby improving the photoelectric conversion efficiency between the materials and improving the charge exchange.Therefore,it is more important to improve the electrochemical performance and photoelectrochemical performance of a single inorganic semiconductor material by recombining two or more inorganic semiconductor materials.Firstly,this paper uses sodium gluconate as the electrolyte to prepare multicolor TiO₂films by anodic oxidation,and studies the effects of different oxidation conditions on the photoelectrochemical performance.Secondly,through the composite of TiO₂films and multi-walled carbon nanotubes(MWCNTs).The method of Ag₂S quantum dots deposition is combined to construct a photoelectrochemical sensor to detect 2,4,6-trinitrotoluene(TNT).Finally,based on the same Ag₂S quantum dot constant potential deposition method and MWCNTs to construct an electrochemical sensor to detect 2,4,6-Trinitrotoluene Nitrotoluene.The main research content and results are as follows:(1)Using sodium gluconate as electrolyte,a series of colored TiO₂films were prepared under different anodic oxidation conditions.The TiO₂films were characterized by SEM,XRD and ultraviolet-visible diffuse reflectance absorption spectroscopy,and different oxidation conditions were studied.Under the anodization current and photoelectrochemical performance.The experimental results show that when the anodic oxidation voltage is low,the TiO₂film does not form a crystalline film,and when the anodic oxidation voltage reaches 100 V,forms anatase TiO₂.The ultraviolet-visible diffuse reflectance absorption spectrum shows that with the increase of the anodizing voltage,the number of absorption peaks in the visible range increases;with the extension of the anodization,the band gap of the visible range decreases,which means that the absorption in the visible region is expanded.In addition,when studying its photoelectrochemical performance,it was found that the photocurrent density of TiO₂film increases with the increase of anodizing voltage and time.And it has the potential to be applied to the field of photoelectrochemical sensors due to its relatively good photoelectrochemical performance.(2)First,sodium gluconate and MWCNTs were used as electrolytes,and colored TiO₂films modified with MWCNTs were prepared by anodizing method,and Ag₂S were deposited onto MWCNTs-TiO₂film by constant potential deposition method.Then SEM,XRD,Raman and other characterizations showed that Ag₂S and MWCNTs were successfully modified on the TiO₂film.The photoelectrochemical performance test shows that Ag₂S quantum dots and MWCNTs can better reduce the electron and hole recombination rate of TiO₂film.Finally,using TNT as the test object,the photoelectric detection performance of Ag₂S-MWCNTs-TiO₂film and MWCNTs-TiO₂film was discussed.The results showed that compared with unmodified TiO₂film,Ag₂S-MWCNTs-TiO₂film has the best photoelectric catalytic effect on TNT.In particular,the detection effect of Ag₂S-MWCNTs-TiO₂film with 12cycles,200 s deposition potential and 0.4 V deposition potential is the best.Under the best conditions,the photoelectrochemical sensor has a significant detection sensitivity for TNT.The detection range is 0.5?100?mol L^-1for linear detection,and the detection limit is 0.165?mol L^-1(S/N=3).(3)Based on the same Ag₂S potentiostatic deposition method as the second system,which deposited on MWCNTs and poloxamer(Px)modified glassy carbon electrodes(GCE)to prepare TNT detection sensor.The prepared Px-Ag₂S-MWCNTs-GCE modified electrode has good catalytic performance for TNT reduction reaction.During the electrodeposition process,some influence factors,such as the deposition cycle number,deposition time,and applied potential of silver sulfide,and the deposition time and applied potential of Px have been inspected.Under optimal conditions,the obtained sensor showed good catalytic performance for the reduction reaction of 2,4,6-trinitrotoluene.The proposed sensor also exhibited excellent stability and reproducibility,providing a wide linear ranges from 0.22 to 15.4?mol L^-1and a low detection limit of 3.23 nmol L^-1(S/N=3).Compared with other methods for detecting TNT,this method has better repeatability,stability and selectivity.