Preparation Of Vanadium Diselenide And In Situ Study On Its Stability

Since the discovery of graphene,two-dimensional materials have become one of the current research hotspots.As a member of two-dimensional materials,vanadium diselenide（VSe₂）has excellent properties such as two-dimensional magnetism,high electrical conductivity and good electrocatalytic performance.It is widely used in integrated circuits,spintronics,electrocatalytic hydrogen evolution and solar cells.There are broad application prospects.At present,it is still very difficult to realize the controllable growth of high-quality two-dimensional VSe₂ single crystals.In this paper,chemical vapor deposition method is used to prepare two-dimensional VSe₂ single crystals.By optimizing the preparation process,the crystal size can be adjusted.On this basis,in situ transmission electron microscopy was used to study the thermal stability and radiation stability of two-dimensional VSe₂.The specific results of the research are as follows:（1）Realize the controllable preparation of high-quality two-dimensional VSe₂single crystals.Two-dimensional VSe₂ single crystals were synthesized by an optimized chemical vapor deposition method,and the prepared VSe₂ single crystals were confirmed to have high crystal quality through the characterization of structure and composition.In addition,the growth law of VSe₂ single crystal was explored by adjusting the growth process parameters.The growth temperature,the quality of the precursors and the spacing of the precursors affect the size of the VSe₂ film.The higher the temperature,the greater the quality and spacing of the precursors,and the larger the size of the VSe₂.The carrier gas flow rate affects the thickness of the VSe₂ film.The faster the carrier gas flow rate,the thinner the VSe₂ film.（2）In situ transmission electron microscopy was used to study the structural stability of two-dimensional VSe₂ under both heating and irradiation conditions.The VSe₂ TEM samples were first prepared by wet etching.In terms of thermal stability research,the phase transition process of two-dimensional VSe₂ at different heating temperatures was observed in real time using a transmission electron microscope in-situ thermal sample stage,and it was found that the phase transition was irreversible.In terms of radiation stability,the stability of two-dimensional VSe₂ samples prepared by mechanical exfoliation method and chemical vapor deposition method under electron irradiation was compared by in-situ transmission electron microscopy,and it was found that the mechanically exfoliated two-dimensional VSe₂ had higher structural stability.In conclusion,the preparation methods and laws of VSe₂ studied in this paper can provide experimental guidance for the controllable growth of high-quality two-dimensional materials.In addition,the research on the structural stability of two-dimensional VSe₂ based on advanced in situ transmission electron microscopy is helpful in promoting the development of advanced two-dimensional electronic devices.