The Research About Preparations And Applications Of Two-Dimensional Layered Nanomaterials

Single or a few layers transition-metal dichalcogenides(TMDs)materials had been widely used in electrochemical energy storage device,catalyst,lubricant and antiseptic owing to their unique electronic structure,high redox activity and excellent mechanical and optical properties.In general,two-dimensional solid materials were combined through a weak van der Waals force between layer and layer.Therefore single or few-layer nanosheets could be easily obtained from their bulk crystals via liquid exfoliation.However,most reported liquid exfoliation methods were time consuming,low yield and not easy to prepare on large scales.To overcome the above disadvantages,we tried to develop rapid,highly efficient and low cost preparing methods of TMDs nanomaterials.We investigated the performance of catalytic,electrochemical and antiseptic of obtained TMDs nanomaterials as well.The main contents were as follows:1.We developed a rapid and highly efficient chemical exfoliation method to produce MoS2 nanosheets with the system of nitrate and hydrochloric acid solution in good yields.In the nitrate/HCl exfoliation solution,ultrasonication accelerated the release of NOCl and Cl2 which weakened the interactions between adjacent layers,resulting in the production of MoS2 nanosheets with high crystallinity and thicknesses less than 5 nm.The chemical exfoliation method could be used to prepare WS2 nanosheets in good yields as well.After successfully preparing MoS2 and WS2 nanosheets,we further researched their application in the field of catalytic and antiseptic.The obtained MoS2 nanosheets exhibited significantly unproved catalytic activity toward the oxygen-reduction and excellent anticorrosion properties.2.Thionyl chloride and pyridine could be mixed to form a kind of strong solubility solvent according to the certain proportions.Due to their similar solubility with aqua regia of precious metal gold(Au)?platinum(Pt)and palladium(Pd),etc,the mixture was named as so-called organic aqua regia.In this chapter,we tried to use organic aqua regia as liquid exfoliation medium to prepare MoS2 nanosheets assisted by ultrasonic.Although organic aqua regia could not exfoliated MoS2 similar to aqua regia,we found that the addition of water would improve the exfoliation of MoS2 to form MoS2 nanosheets successfully owing to the release of SO2 gas.Consequently,the exfoliated MoS2 nanosheets were doped into PANI polymer to see if the MoS2 nanosheets could be used for electrochemical energy storage device.Unfortunately,the performance of supercapacitor was not improved obviously.3.A facile strategy was developed to synthesize polyaniline/MoS2(PANI/MoS2)nanocomposites via in situ polymerization.Structural and morphological characterizations of MoS2 nanosheets and the nanocomposites were investigated by scanning electron microscope(SEM),transmission electron microscope(TEM),and X-ray powder diffraction.The results of SEM illustrated that orderly sawtooth polyaniline(PANI)nanoarrays were formed on the surface of MoS2 nanosheets.The nanocomposites displayed good electrochemical performance as a supercapacitor electrode material.The specific capacitance reached 560 F/g at a current density of 1.0 A/g in 1.0 M H2SO4 solution.The good performance was probably ascribed to the MoS2 nanosheets which provided a highly electrolytic accessible surface.