The Preparation And Photocatalytic Activities Of Black Phosphorus And Its Composites

Semiconductor photocatalytic technology is considered as a sustainable and renewable way to alleviate energy shortage and solve environmental pollution.The development of efficient photocatalysts,especially the metal-free photocatalysts,is one of the key factors to overcome photocatalytic technology.In recent years,2D materials have developed rapidly,especially in 2014,black phosphorus?BP?was successfully exfoliation into mono-or few layers of phosphorene.This 2D layered metal-free material is widely used in photocatalysis and other fields because of its unique properties such as tunable directly band-gap,ultrahigh charage mobility,strong optical absorption,large specific surface area and anisotropy structure.Unfortunately,the high preparation cost and harsh preparation conditions of black phosphorus crystals limit the large-scale application of black phosphorus.on the other hand,single-or few-layer black phosphorene has limited its application in the field of photocatalysis due to chemical instability and fast photogenerated carrier recombination.The main contents of this paper are as follows:?1?At present,the preparation and sale price of black phosphorus is very high,which brings great obstacles to its application.In this paper,black phosphorus with high yield was prepared by chemical vapor transport reaction with low-cost and high-purity red phosphorus as precursors.the best preparation conditions were found by comparing different phosphorus sources and preparation conditions.In addition,XRD,ICP-OES and other characterization methods were used to analyze the quality of black phosphorus from different phosphorus sources.The results showed that the crystallinity and purity of black phosphorus crystal can reach 98.81%and 99%respectively.The crystal of black phosphorus was further simulated and analyzed by VESTA software,it turned out that the crystal of was orthorhombic,which was consistent with the results of Raman?2?To further improve the stability of the application of phosphenes in the field of photocatalysis,on the basis of the previous preparation work of phosphenes,the phosphenes with excellent structures and morphologies were firstly prepared by ultrasonic-assisted liquid-phase stripping method.Then TiO₂/phosphene heterojunc-tion photocatalysts with different morphologies were prepared by a simple liquid phase mixing process.By means of XRD,XPS,SEM and UV-vis,the physicochemical properties of the composite photocatalyst were analyzed,and then the activity of hydrogen production over the composite photocatalysts were also studied.The results showed that,BP/BN-TiO₂ has the highest hydrogen evolution rate in the full band and visible light??>420 nm?,the values of which were 39.15mol·g^-1·h^-1 and 36.87 mol·g^-1·h^-1 respectively,which were 1.99 times and 2.4 times higher than those of BN-TiO₂.Besides,the photocatalytic hydrogen evolution activity of BP/BN-TiO₂ kept stable after five cycle experiments.