Study On The Preparation Of Black Phosphorus Nanosheets And The Properties Of Their Composites

In this study,bulk black phosphorus was prepared by chemical vapor transfer method,and the bulk black phosphorus was peeled off into black phosphorus nanosheets by electrochemical peeling method assisted by liquid peeling.By loading different nanomaterials onto the black phosphorous nanosheets,photocatalytic hydrogen evolution performance and photothermal loading and exchange performance of the black phosphorous nanosheets are improved.SEM and TEM were used to observe their microscopic morphology and structures,and XRD,Raman,and XPS were employed to characterize crystal structures and element compositions.Finally,photocatalytic hydrogen evolution performance and photothermal conversion performance of different black phosphorus composites were tested respectively,and their improvement mechanisms were analyzed.（1）Red phosphorus is used as phosphorus source,Sn powder and Sn I₄ are used as black phosphorus growth mineralizers,and vacuum quartz tubes are used as reaction ampoules.The metallic bulk black phosphorus is synthesized by chemical vapor transfer method.The synthesized black phosphorus has stable structure,high purity,and large output,which is beneficial to the applications of black phosphorus-based catalysts.Black phosphorus is used as the working electrode of electrochemical systems,platinum wire is used as the auxiliary electrode,TBATFB and DMSO are used as the electrolytes.The sponge-like black phosphorus nanosheet clusters were prepared by electrochemical stripping method,and the phosphorus clusters were liquid stripped using the cell powder extraction machine,and finally the black phosphorus nanosheets with stable morphology and uniform dispersion were obtained.The black phosphorous nanosheets were characterized and tested.The tests found that the nanosheets have characteristics of high purity,less oxidation,smooth surface,clear edges,and stable morphology.The photocatalytic performances of black phosphorous nanosheets were tested,which showed photocatalytic application potential and proved broad development prospects of black phosphorous as photocatalytic hydrogen production catalyst.（2）Using cadmium acetate,zinc acetate and sodium sulfide,CZS nanoparticles were prepared by hydrothermal method.CZS nanoparticles have a clear structure,a stable spherical morphology,and an average particle diameter of about 50 nm.The black phosphorous nanosheets and CZS nanoparticles obtained from the stripping were fully dispersed in the dispersion by ultrasonic cavitation,and then combined to prepare the BP-CZS composite.The composite was characterized and tested for performances.The test found that the composite has an OD/2D structure,the composite structure is stable,and the reduction of surface-active sites caused by the self-aggregation effect of CZS nanoparticles is decreased to effectively increase the catalytic reaction surface area.The photocatalytic hydrogen evolution test showed that the 7%ratio of BP=CZS catalyst has the best photocatalytic hydrogen evolution performance,and its photocatalytic hydrogen evolution yield is 2817μmol h^-1 g^-1,which is much higher than pure black phosphorus nanosheets(147μmol h^-1 g^-1),2.2 times that of pure CZS nanoparticles(1257μmol h^-1g^-1).In summary,the BP-CZS composite exhibits excellent photocatalytic hydrogen evolution performance,which proves its application potential in the field of photocatalytic hydrogen evolution.（3）Using the prepared black phosphorous nanosheets as a support,small-sized GDY nanosheets were loaded by in-situ growth,and the prepared BP-GDY composite material has a stable structure.A variety of methods were used to characterize the morphology and structure of the BP-GDY composite.Performance tests showed that small-sized GDY nanosheets are uniformly attached to the surface of black phosphorus nanosheets,so that the black phosphorus nanosheets that are easy to agglomerate can be dispersed freely,at the same time,the black phosphorous nanosheets still maintain a complete sheet structure after being compounded,and the edges are clearly visible,which proves the stability of the structure.The photothermal performance curves of the samples under different concentrations and different illumination powers were tested.The infrared thermal imager was used to visually observe the heating process of the samples under illumination,and finally their photothermal conversion efficiency was calculated.The results showed that the composite sample has an excellent conversion efficiency of 39.3%,which is higher than the black phosphorus nanosheet and the GDY nanosheet.Excellent photothermal conversion performance indicates potential applications of black phosphorous-based photothermal materials.