Controlled formation of multiple core-shell structures in metal-organic frame materials for efficient microwave absorption

Abstract

The design of metal–organic frameworks (MOF) derived composites with multiple loss mechanisms and multi-scale micro/nano structures is an important research direction of microwave absorbing materials. Herein, multi-scale bayberry-like Ni-MOF@N-doped carbon composites (Ni-MOF@NC) are obtained by a MOF assisted strategy. By utilizing the special structure of MOF and regulating its composition, the effective improvement of Ni-MOF@NC's microwave absorption performance has been achieved. The nanostructure on the surface of core–shell Ni-MOF@NC can be regulated and N doping on carbon skeleton by adjusting the annealing temperature. The optimal reflection loss of Ni-MOF@NC is −69.6 dB at 3 mm, and the widest effective absorption bandwidth is 6.8 GHz. This excellent performance can be attributed to the strong interface polarization caused by multiple core–shell structures, the defect and dipole polarization caused by N doping, and the magnetic loss caused by Ni. Meanwhile, the coupling of magnetic and dielectric properties enhances the impedance matching of Ni-MOF@NC. The work proposes a particular idea of designing and synthesizing an applicable microwave absorption material that possesses excellent microwave absorption performance and promising application potential.