Preparation, Characterization And Electrochemical Study Of Sulfide Nanomaterials

Metal sulfides are important narrow-gap semiconductor materials, nanoscale metal sulfides have attracted extensive attention due to their electrical and optical properties. Because of these, nanostructured sulfides have exhibited promising applications in many fields, such as sensing, magnetics, catalysis, optics,batteries. In this dissertation, tentative explorations had been carried out on synthesis nickel sulfide and bismuth sulfide, including their formation mechanisms and electrochemical applications.This graduation thesis includes several sections, as follows:1. In this part, nanomaterials and the recent research progress in electrochemical application of nanomaterials modified electrodes were described. In addition, a comprehensive discussion about the research of the metal sulfides nanomaterials and an explanation of the research status of preparing method were reviewed. And in the end, the research target and research mentality of this thesis were also introduced.2. Single phase cubic NiS2were synthesized by the reaction of nickel nitrate and thioacetamide in ethanol via a solvothermal process in the temperature of150℃. XRD, SEM, EDS were utilized to characterize the products. The results showed that the obtained products were spherical phase with a diameter of about100nm. And the mechanism of hydrothermal process was analysed according to the phenomenon and literatures. The nanostructured NiS2were used to modified the glassy carbon electrode, Electrocatalysis for L-cysteine on the modified electrode was studied by cyclic voltammetry in0.1mol NaOH. The experimental results had shown that sulfide surface was coated with a hydroxide film at the high pH, resulting in the electrokinetic behavior similar to that of nickel hydroxide. L-cysteine was electrocatalyzed indirectly by the Ni(OH)2/NiOOH redox couple in the alkaline solution.3. Nanostructured bismuth sulfide were prepared by hydrothermal method at100℃,using bismuth nitrate and thioacetamide as bismuth source and sulfur source. The products were characterized by XRD, SEM. The results show that bismuth sulfide nanoparticles with a diameter of about40nm were orthorhombic phase. The obtained products were used to modify the glassy carbon electrode. Voltammograms of the modified electrode were carried out in0.1M NaOH containing0.1M Na2S. It showed that the samples exhibited excellent attachment, the redox of Bi3+/Bi2S3depended on the concentration of HS-and H+. But its electrocatalytical performance needed further study.4. Ni and Ag nanoparticles modified glassy carbon electrodes were prepared by cyclic voltammetry in different ratio of AgNO3and Ni(NO3)2in1%NH3solution. The deposition potential range suitable for the deposition had been optimized. The electrochemical signals of L-cysteine on Ni/GCE and Ag-Ni/GCE were compared in pH7.4buffer solution and0.1M NaOH. The electrochemical behavior of modified electrodes was investigated by cyclic voltammetry and potentiostatic method. The results showed that Ni/GCE and Ag-Ni/GCE exhibit excellent catalytic effects on electrochemical reactions of L-cysteine in0.1M NaOH. The oxidation peak current showed a good linear relationship with L-cysteine concentration in the range of1×10-6～5×10-6mol/L. The redox reactions of Ni(OH)2/NiOOH on modified glassy carbon electrode were controlled by diffusion process. The presence of Ag had little advantageous to enhancing the electrocatalysis of Ni toward L-cysteine.