Preparation Of Tungsten Chalcogenide And Their Catalytic&Adsorption Properties

Due to their unique structures,transition metal sulfide compounds have attracted extensive research interest in many fields such as photoelectricity,catalysis,sensing and storage devices.In recent years,the methods of synthesis of transition metal sulphides by vapor deposition,stripping,solvent heating and colloid have become more and more mature.In this thesis,the tungsten chalcogenide were synthesized by colloid method and solvothermal method.Their applications in catalyzed amine coupling reaction and adsorption of methylene blue were studied.The main research contents are as follows:?.Synthesis of ultrathin WSe2 nanosheets and their high-performance catalysis for conversion of amines to iminesWSe2 nanosheets were synthesized from tungsten hexachloride and selenium powder by colloidal method,and its composition,valence,morphologies and properties were characterized.The results showed that the monolayer of the synthesized WSe2 nanosheet was about 0.7 n,,and the nanosheets aggregated to form a flower-like nanostructure.The product was dispersed in N-methyl-2-pyrrolidone with strong blue fluorescence under ultraviolet light.The high performance in the coupling of amines to imines could be due to the typical layered crystal structure of WSe2 with a large surface area,more active sites than counterpart bulks,availing to improve the catalytic performance of the material.In order to explore the generality of catalytic performance,the coupling reactions of various amines were catalyzed and showed good catalytic performance.Further experiments were carried out to research the mechanism of benzylamine coupling reaction by WSe2 nanosheets.Moreover,H2O was used as solvent in catalytic process,avoiding expensive and toxic organic solvents.This work provides a green and economical method for the synthesis of imide.?.Synthesis of WS2 nanosheets and their high-performance catalysis for conversion of amines to iminesThe loosely assembled WS2 nanosheets were prepared by colloidal method,and their composition,morphology and properties were characterized by XRD,TEM,XPS,UV-vis,Raman and other tests.The obtained samples had strong photoluminescence in the visible light range.Imide is an important intermediate of a series of fine chemicals.The preparation of imide by catalytic oxidation of amines has attracted extensive attention due to the use of O2 as a green oxidant and the generation of water as a by-product in the reaction.The synthetic photoactive WS2 was used as a catalyst to convert amines into imines,and the generality of catalytic performance was studied.WS2 nanosheets exhibited great catalytic performance and excellent recyclability.?.Synthesis of W18O49 nanowire and their application in adsorption of methylene blueThree different structures W18O49 nanowires were synthesized by solvothermal method with different solvents.The local surface plasmon resonance caused by a large number of oxygen vacancies on the sample surface makes them have a very wide and strong absorption band from visible light to near infrared.The adsorption capacity of the samples to methylene blue,which is an organic pollutant used in the laboratory measurement model,was studied.The results showed that the adsorbents have high adsorption capacity for methylene blue.At room temperature,the maximum adsorption capacity of the W18O49-E?W18O49-I?W18O49-B is 115.1 mg/g,101.1 mg/g,125.1 mg/g,respectively.The adsorption behavior conforms to the Lamgmuir isotherm model and the pseudo-secondary kinetic model.