Preparation Of Metallic Sulfides And Their Derivatives And Their Applications In Photoelectrocatalysis And Sensing

The rapid development of nano-science and technology has greatly promoted the the application of nanomaterials in detection and catalysis.Among them,sulfide-based nanomaterials have attracted enormous attention due to their narrow band gap and strong absorption of visible light.It is considered to be one of the most attractive semiconductor materials.In this thesis,bismuth sulfide,vanadium doped bismuth sulfide and indium sulfide nanomaterials were successfully prepared by hydrothermal method,and the hydrogen evolution performance of bismuth sulfide and vanadium doped bismuth sulfide when used as photoanode in visible light,and the detection ability of indium sulfide as a photoelectric sensor for thallium ion were also studied.The main research contents and results are listed as follows:?1?preparation of Bi₂S₃ nanowire thin film:the Bi₂S₃ thin film with nanowire crystal was successfully prepared by facile hydrothermal method.SEM indicates that the bismuth sulfide nanowires film exhibit strong anisotropic with a thickness about560 nm.XRD shows that Bi₂O₃ is monoclinic structure while Bi₂S₃ is rhombic structure.The optical current density of Bi₂S₃ nanowire thin film is about 5 mA·cm^-2?-0.2 V vs Ag/AgCl?.The prepared Bi₂S₃ exhibit a low band gap about 1.3-1.7 eV and present strong absorption of visible light.However,there is still a certain gap between the photocurrent density and the theoretical photocurrent value of Bi₂S₃.It can be ascribe to the fast charge recombination rate of Bi₂S_3,and thus reduces the photoelectric conversion efficiency.In addition,the photocurrent value of Bi₂S₃decays to 50.4%of the initial current after 1 hour of continuous illumination,mainly because Bi₂S₃ suffers from severe photocorrosion,which seriously limits its application in photochemistry.?2?preparation of V-Bi₂S₃ nanowires:V-Bi₂S₃ nanowires were prepared by hydrothermal reaction with bismuth nanoparticle film as the bismuth source and thiourea as the sulfur source through the process of solid phase film prebody-solution-solid phase film product.SEM shows the tropism anisotropy of V-Bi₂S₃ generated,and the film thickness is about 582 nm.XRD shows that BiVO₄ is monoclinic structure and V-Bi₂S₃ is rhombic structure.The visible light photocurrent density of V-Bi₂S₃ nanowire thin film is about 12 mA·cm^-2?-0.2 V vs Ag/AgCl?.Hydrogen production after 1 hour is about 70?mol.Compared with the pure Bi₂S₃nanowire,the photocurrent density of the sample has been greatly improved.It is mainly due to a new charge in the lattice of Bi₂S₃ introduced by vanadium doping,and forming a surface or changing the type of lattice defects,and gives raise to a flexible configuration of electronic and thus changing the band structure of the photocatalytic activity of the semiconductor material.V⁵⁺ions can also be used as electron donors to improve the carrier concentration and semiconductor n-type characteristics of Bi₂S₃,and further improve the electron mobility and charge life.In addition,after one hour of continuous illumination,the photocurrent value decreased significantly compared with the pure Bi₂S₃ prepared by the former,and the photocurrent density value after 1 hour remained at 84.6%of the initial current.It may be that doping increases the separation and transmission rate of photogenerated carriers,and more photogenerated holes reach the electrode surface to participate in chemical reactions,rather than the occurrence of bulk self-corrosion.?3?preparation of In₂S₃ nanosheets and the application in Tl⁺detection:In₂S₃nanosheets were prepared by hydrothermal method,and then placed in industrial wastewater with different amounts of Tl⁺.The purpose of Tl⁺detection was achieved through changes in photoelectric chemical signals before and after immersion.The innovation of this work lies in the first attempt to detect Tl⁺by constructing photoelectric chemical sensor,and the sensor has good detection performance.The experimental results show that the photoelectric sensor has good selectivity and anti-interference ability.Moreover,when[Tl⁺]was less than 10?M,the attenuation of photocurrent presented a good linear relationship with the concentration of[Tl⁺]?R²=0.9992?.