Controllable Construction Of Monodisperse Nickel (cobalt) Phosphide Nanocrystals/graphene And Its Electromagnetic Absorption Properties

While electromagnetic waves bring convenience to human life,they are also accompanied by many pollution problems.It is necessary to use some electromagnetic shielding materials to weaken the threat of electromagnetic waves to human health.At the same time,electromagnetic shielding materials are also widely used in stealth fighters and warships to achieve radar stealth.Therefore,it is necessary to develop some electromagnetic absorption materials.Excellent electromagnetic shielding materials need to meet the characteristics of low cost,excellent performance and long life.In-situ growth of monodisperse phosphide nanoparticles on the surface of graphene can greatly enhance the interface polarization effect of composite materials and is an ideal electromagnetic wave absorbing material.However,the dispersibility and size control of nickel phosphide nanoparticles grown in situ on graphene are still very challenging.In this paper,a thin layer of graphene was successfully prepared in the laboratory by an improved hummer method,and then by freeze-drying,an ultra-light graphene aerogel with hydrophobic surface was obtained.The graphene aerogel is added to the phosphide synthesis reaction to obtain in-situ monodisperse transition metal phosphide/graphene composite materials.In this article,we use high-temperature pyrolysis to controllable structure of monodisperse Ni₂P nanoparticles,and make them uniformly dispersed on the surface of rGO.By controlling the amount of rGO added and the reaction time,monodisperse size mosaic nickel phosphide nanoparticles were obtained.The size of the large mosaic particles is about 45 nm,and the size of the small mosaic particles is about 6 nm.By analyzing the electromagnetic wave absorption test data of the material,it can be concluded that it has excellent electromagnetic wave absorption characteristics in the range of 2-18 GHz.When the thickness of the test sample prepared with 30 wt%Ni₂P/rGO mosaic Ni₂P/rGO is 2.5 mm,the minimum R_L reaches-38.3 d B.When the sample thickness is 1.5 mm,the effective absorption bandwidth of 30 wt%Ni₂P/rGO reaches 3.79 GHz.The excellent electromagnetic absorption characteristics of the composite material are attributed to the scattering of electromagnetic waves by the larger mosaic particles grown in situ on the graphene and the large number of interface polarization sites between the smaller mosaic particles and the graphene.This synthesis strategy provides a reference for the future in-situ growth of nanoparticles on the surface of graphene and the design of EMI materials.In addition,we have also synthesized cobalt phosphide nanomaterials with different morphologies for electrocatalysis and electromagnetic shielding research.The test results show that the Co₂P/rGO material we synthesized has good electrocatalytic performance and electromagnetic shielding performance.When the content of the Co₂P nanorod/rGO sample is 30 wt%and the thickness is 2.5 mm,the R_L reaches a minimum of-30.5 d B.When the thickness is 1.5 mm,the effective absorption bandwidth of the 30wt%Co₂P nanorod/rGO sample reaches 3.28 GHz.