Study On The Morphology Design And Microwave Absorption Properties Of NiCo₂O₄/Carbon-based Composites

High-performance microwave absorbing materials can reduce or even eliminate useless electromagnetic waves through a variety of energy conversion processes,which is a major measure to solve the problem of electromagnetic pollution.In this paper,a series of Ni Co₂O₄/carbon-based composites with different morphologies were prepared based on the bimetallic oxide Nickel cobaltate（Ni Co₂O₄）and different carbon-based materials,and the microwave absorption properties were studied.The main research results are as follows:（1）A step-by-step hydrothermal method combined with a heat treatment process was used to prepare a rod-like Ni Co₂O₄/reduced graphene oxide（Ni Co₂O₄/RGO）composite.The results show that GO forms a three-dimensional porous structure of RGO foam through the reduction and self-assembly process,in which rod-like Ni Co₂O₄is uniformly wrapped by RGO film.This special structural design improves the microwave absorbing performance of Ni Co₂O₄/RGO composites.Specifically,when the Ni Co₂O₄/RGO filling amount is 30%,the minimum reflection loss(RL_min)is-64.5d B（3.47 mm）,and the effective absorption bandwidth（RL<-10 d B）is 5.3 GHz（1.56mm）.（2）A simple one-step hydrothermal method combined with a heat treatment process was used to prepare a rod-like Ni Co₂O₄/helical carbon nanotube（Ni Co₂O₄/HCNT）composite.The results show that the combination of rod-like Ni Co₂O₄ and one-dimensional helical carbon nanotubes forms an interpenetrating network structure,which optimizes the microwave absorbing properties of the composite.Specifically,when the filling amount is 50%,Ni Co₂O₄/HCNT exhibits the best absorbing performance.When the absorber thickness is only 1.35 mm,the RL_min is-55.9 d B,and the corresponding effective absorption bandwidth is 4.8 GHz.It is worth noting that in the low thickness area（1.35-2.10 mm）,the effective absorption bandwidth can completely cover the X and Ku bands.（3）The needle-like Ni Co₂O₄/carbon cloth fiber（Ni Co₂O₄/CCF）composite was prepared by hydrothermal method and heat treatment process.The results show that a sheath structure composed of needle-like Ni Co₂O₄ is uniformly grown on the surface of the CCF,which is conducive to microwave absorption.Specifically,when the Ni Co₂O₄/CCF filling amount is 25%,the RL_min at 2.96 mm thickness reaches-62.1 d B（C band）,the RL_min at 5.50 mm thickness is-42.4 d B（S band）,and the 1.43 mm thickness The effective absorption bandwidth is 6.0 GHz（Ku band）.Figure[35]Table[6]References[108]...