Promoting the microwave absorption performance of hierarchical CF@NiO/Ni composites via phase and morphology evolution

Lightweight and efficient carbon-based microwave absorbents are significant in addressing the increasing severity of electromagnetic pollution.In this study,hierarchical NiO/Ni nanosheets with a tuneable phase and morphology supported on a carbon fiber substrate(CF@NiO/Ni)were fabricated using a hydrothermal approach and post-annealing treatment.As the annealing temperature increases,more metallic Ni is formed,and an apparent porosity appears on the sheet surface.Benefiting from the advantages of a three-dimensional(3D)conducting network,hierarchical porous structure,reinforced dipole/interface polarization,multiple scattering,and good impedance matching,the CF@NiO/Ni-500 composite exhibits an excellent microwave absorption performance even at a filling rate of only 3wt%.Specifically,its minimal reflection loss is-43.92 dB,and the qualified bandwidth is up to 5.64 GHz.In addition,the low radar cross-section area of the CF@NiO/Ni composite coating confirms its strong ability to suppress electromagnetic wave scattering.We expect that this work could contribute to a deeper understanding of the phase and morphology evolution in enhancing microwave absorption.