Preparation And Microwave Absorbing Properties Of Wood-derived Carbon With Ordered Channels Decorated By NiCo₂O₄

Microwave absorption(MA)materials are of great significance for preventing electromagnetic pollution,strengthening communication security,and developing military anti-reconnaissance technology.However,the MA materials developed are too high in density,thicker coatings and poor absorption performance,which are difficult to meet the increasing development requirements of MA materials-"light,thin,wide,strong".Traditional carbon materials are expected to be widely used in the field of absorbing materials due to their excellent dielectric properties,low density and stable chemical properties,but they are also limited by poor impedance matching performance and complex preparation processes.It is proposed that the ordered pore structure of carbonized wood(CW)is used as the skeleton,and NiCo₂O₄ is loaded on the inner wall of the ordered channels by a simple impregnation and calcination method to prepare an ordered pore structure.The wood-derived carbon/NiCo₂O₄(CW/NiCo₂O₄)composite material effectively solves the above-mentioned problems.At the same time,the preparation method uses natural wood with a large natural reserve,and has the advantages of environmental friendliness and low price.The as-prepared materials were characterized by XRD,Raman,XPS,SEM and other characterization methods.SEM showed that the wood-derived carbon has ordered through channels with different pore sizes.The loaded NiCo₂O₄ showed a short cone shape and uniformly distributed in the pores.On the inner wall.Furthermore,the use of XRD,Raman,and XPS demonstrated that there are a large number of defects in wood-derived carbon and NiCo₂O₄.These defects will become the center of the dipole polarization in the electromagnetic field,thereby enhancing the dielectric loss performance.In addition,there are a large number of interfaces between wood-derived carbon and NiCo₂O₄,which may cause interface polarization and enhance microwave absorbing performance.The electromagnetic parameters are adjusted by changing the carbonization temperature of wood-derived carbon,the arrangement direction of ordered pores and the introduction of NiCo₂O₄.It is found that as the carbonization temperature increases,the dielectric constant of the material continues to increase;the introduction of NiCo₂O₄reduces the sensitivity of the dielectric constant of the material to changes in the carbonization temperature;the ordered material structure has a larger dielectric constant than the disordered material And the CW/NiCo₂O₄ composite material achieves excellent absorption performance with strong absorption and wide absorption band when the ordered channels are perpendicular to the incident direction of electromagnetic waves.In addition,COMSOL is used to simulate the distribution of loss power density of ordered CW/NiCo₂O₄ composites at lower carbonization temperatures,which shows that when ordered pores are arranged horizontally relative to the incident direction of electromagnetic waves,they can effectively interact with electromagnetic waves to enhance the absorption performance.Finally,the reflection loss(RL)of the ordered channels in other alignment directions is simulated,and the absorbing performance in other alignment directions is predicted.This simple,efficient,environmentally friendly preparation process and the prepared ordered CW/NiCo₂O₄ composite material provide a new idea for the development and application of a new generation of lightweight and high-performance absorbing materials.