Preparation And Properties Of Low-dimensional Black Phosphorus

Due to its small size,low-dimensional nanomaterials have some unique properties compared with bulk materials of the same composition,such as surface effects,small size effects and macroscopic quantum tunneling effects,which have become the research hotspots in recent years.Graphene is the most typical two-dimensional material with high carrier mobility,transition metal sulfides represented by molybdenum disulfide have excellent switching ratio,and both materials have attracted attention.However,their inherent defects?low switch ratio of graphene and low mobility of molybdenum disulfide carriers?have limited their application range to a certain extent,and low-dimensional black phosphorus makes up for the shortcomings of the two due to its excellent performance,and has broad application prospects,which has aroused great research interest.The main research work of this thesis includes the preparation,performance characterization and anti-oxidation research of low-dimensional black phosphorus.The specific research work is as follows:?1?Using NMP as solvent and block black phosphorus as raw materials,two-dimensional black phosphorus was prepared by microwave method and characterized by SEM,TEM and AFM.The results show that a uniform size of two-dimensional black phosphorus can be successfully prepared at a temperature of175?and a microwave time of 4 h.?2?Using DMSO as solvent and block black phosphorus as raw materials,black phosphorus quantum dots were prepared by microwave method.The effects of reaction temperature and microwave time on the formation of black phosphorus quantum dots were studied,and TEM,AFM,XRD,Raman,UV-vis and PL characterization.The results show that the size of the prepared black phosphorus quantum dots decreases with increasing temperature within a certain temperature range.With the extension of microwave time,the black phosphorus quantum dots were continuously peeled off from the sheet.When the reaction time was 4 h,the black phosphorus sheets were completely stripped,and the uniformly dispersed black phosphorus quantum dots were obtained.?3?Al₂O₃ protective layers with different thicknesses were deposited on the surface of black phosphorus quantum dots by ALD equipment.The protective effect of film thickness on black phosphorus quantum dots was studied.The surface composition and chemical state of the samples were characterized by XPS.The results show that the Al₂O₃ film with a thickness of 20 nm allows the black phosphorus quantum dots to be exposed to air for 15 days without being oxidized.?4?The effects of annealing temperature on the stability of the two-dimensional black phosphorus samples were investigated by microwave annealing at different temperatures.The results show that when the annealing temperature is too high,easily decomposes the two-dimensional black phosphorus.Annealing at 250?can effectively improve its stability.