Controlled Construction Of Monodisperse Nickel-based Alloy/Graphene And Its Electromagnetic Absorption Properties

With the rapid development and application of electronic products in commercial,industrial,medical and military fields,electromagnetic interference caused by electromagnetic radiation is becoming more and more serious.In order to completely disappear electromagnetic interference and electromagnetic pollution,the key is to develop new high-performance electromagnetic absorbing materials.Graphene is a kind of nanomaterial with the smallest thickness and the strongest electrical and thermal conductivity that has been explored so far.It has obvious advantages such as stable chemical properties,large specific surface area and adjustable dielectric properties.However,its high electrical conductivity limits its application in electromagnetic wave absorption.Metallic nickel is beneficial for research in the field of electromagnetic wave absorption due to its excellent properties of compatible dielectric loss and easy production,but pristine nickel particles cannot provide the desired electromagnetic wave absorption properties.Therefore,the two materials are combined to improve the electromagnetic wave absorption performance of each other.The nickel base alloy/graphene composite studied in this paper is a new kind of electromagnetic wave absorbing material.In this paper,monodisperse nickel(Ni)nanoparticles grown in situ on the surface of reduced graphene oxide(r GO)were controllably synthesized using a high-temperature pyrolysis method.This method can controllably prepare nanoparticles with smaller size and more uniform particle dispersion,and can greatly enhance the polarization sites between the particles and r GO,so that the material has higher electromagnetic wave absorption performance.By controlling the reaction time,the r GO solution was injected into the reaction solution when the color of the reaction solution turned black at 210℃,and the monodisperse small size Ni/r GO composite was obtained.Various characterization results showed that Ni nanoparticles successfully grew on the surface of r GO,presenting a monodisperse state and relatively uniform size,with a particle diameter of about 5.86 nm.Electromagnetic parameter measurement results show that when the coating thickness of Ni/r GO-150 sample is 2.5 mm and the frequency is 9 GHz,the return loss(R_L)value can reach-39.4 d B,which can effectively absorb the electromagnetic wave generated by X band(8～12 GHz),and the electromagnetic wave absorption effect is the best in this band range.When the coating thickness is 1 mm,the maximum effective absorption bandwidth is 3.3 GHz(13.1～16.4 GHz),which can absorb more than 99.9%of electromagnetic waves.Monodisperse cobalt-nickel(Co Ni)alloy nanoparticles grown in situ on the surface of r GO were synthesized by the same method.Various characterization results showed that Co Ni nanoparticles successfully grew on the surface of r GO,presenting a monodisperse state and relatively uniform size,with a particle diameter of about 3.88 nm.When the coating thickness of Co Ni/r GO-100 sample is 2.0 mm and the frequency is 10 GHz,the return loss(R_L)value can reach-36.8 d B,which can effectively absorb the electromagnetic wave generated by X band(8～12 GHz).When the coating thickness is 1.5 mm,the maximum effective absorption bandwidth is 3.4 GHz(12.3～15.7 GHz),which can absorb more than 99.9%of electromagnetic waves.In conclusion,Ni/r GO and Co Ni/r GO nanocomposites have excellent electromagnetic wave absorption performance,which can effectively alleviate electromagnetic interference and electromagnetic pollution,and have potential application value in the field of electromagnetic wave absorption materials.