Research On Liquid Exfoliated Few-layered WSe₂ Two-dimensional Materials And Their Properties

As a kind of transition metal dichalcogenide?TMDs?material,WSe₂ has great potential applications in many fields and has received more and more attentions.At present,although there are many studies on two-dimensional materials,the method of obtaining two-dimensional material films is always limited to small-scale preparation in the laboratory.Our research focuses on WSe₂ and tries to find a simple and reproducible method to fabricate large-area films assembled by WSe₂ nanosheets on a large scale.And the WSe₂ film was applied to a thin film transistor and an electrochemical hydrogen evolution reaction?HER?catalyst.In this study,the WSe₂ bulk powders were pretreated by supercritical exfoliation method to expand the WSe₂ layer spacing.Then,during the liquid phase exfoliation,the parameters such as power were adjusted,and sodium deoxycholate?SDO?was selected as the surfactant to stay the dispersion stable.WSe₂ nanosheets with the average size of40.2 nm,about 5-7 layers,were fabricated by this method.Afterwards,the WSe₂ film was assembled on the substrate by the space-confined self-assembly method,and a uniform film with a diameter of about 4 cm was obtained at one time,and successfully loaded on nine 10×10 mm 300 nm Si O₂/Si substrates.The WSe₂ film can then be made into a thin film transistor,and it was measured as a p-type semiconductor.The carrier mobility isconductive glass to prepare an electrochemical hydrogen evolution reaction?HER?catalyst electrode.It was found that the smaller the size and thickness of the WSe₂nanosheet,the higher the measured catalytic activity,since the active sites of WSe₂ are mainly distributed at the edges of the sheets.In summary,this study can prepare WSe₂ nanosheets on a large scale by supercritical exfoliation and liquid exfoliation as a two-step method.And WSe₂ nanosheets were assembled on different substrates by the space-confined self-assembly method.There is great potential for application in thin film transistors and electrochemical hydrogen evolution reaction catalysts.