Study On The Catalytic Preparation Of Black Phosphorus And Its Catalytic Mechanism

Black phosphorus（BP）is an allotrope of phosphorus with a natural fold structure,which is similar to graphite but have differences.Due to this special structure,black phosphorus has many excellent properties,such as high carrier mobility,adjustable direct band gap,good photoelectric properties and good anisotropy,etc.,and owing to these good properties,black phosphorus have a good prospect in the field of sensing,energy storage,catalysis,medicine and others.Unfortunately,the preparation of black phosphorus limited the development of black phosphorus,therefore,the preparation method has attracted wide attention.For the mineralization method has the advantages of good crystallization,good reproducibility,mild conditions,non-toxic and green,etc.,this paper carried out a series of explorations on the preparation of black phosphorus by the mineralization method and solved some existing problems,moreover,this paper also further explored the catalytic mechanism of black phosphorus.Firstly,in order to increase the single production of black phosphorus,a muffle furnace with a large volume was used to prepare black phosphorus.Analyzed by X-ray diffraction（XRD）,Raman and SEM,the prepared black phosphorus has good crystallinity.Furthermore,In order to solve the problem of low purity of black phosphorus,a method of purifying black phosphorus has been developed.The black phosphorus was purified by hydrogen peroxide,concentrated hydrochloric acid and anhydrous ethanol,characterized by X-ray diffraction,Raman and SEM,the results showed that the impurities,such as red phosphorus,white phosphorus,phosphating substance,metallic tin and iodide,could be effectively removed by purifying treatment,and the original structure of black phosphorus was not destroyed.Secondly,in order to improve the yield of black phosphorus,it is necessary to optimize the process parameters（mainly heating temperature,holding time and calcining method）for the preparation of black phosphorus.X-ray diffraction was used to characterize and analyze the black phosphorus that obtained from different synthesis routes.The results showed that the black phosphorus with good crystallinity,the impurity content was significantly reduced and the conversion rate was improved under the second calcination.Under optimized conditions,the yield of black phosphorus reached 92%.Analyzing the affecting factors of black phosphorus yield so that can lay a foundation for the preparation of black phosphorus by catalytic method.Finally,to complete the catalytic mechanism of black phosphorus,we need prepare the ternary complex Sn₂₄P_19.3I₈.By optimizing experimental conditions,the ternary complexes were successfully prepared.Using the ternary complexation catalysis to prepare black phosphorus and further exploring the catalytic formation mechanism of black phosphorus.The black phosphorus was characterized by X-ray diffraction,Raman spectrum and SEM.The results show that black phosphorus is separated from ternary complex,which is inconsistent with the phenomenon reported in literature.Therefore it is speculated that there exists a gaseous transition state in the process of black phosphorus,so that we prepare a new black phosphorus catalytic mechanism.