Polymetallic MOF-derived corn-like composites for magnetic-dielectric balance to facilitate broadband electromagnetic wave absorption

Abstract

The broadband electromagnetic wave absorption (EMWA) property of a material is governed by its electromagnetic impedance matching, but an effective regulation strategy to enhance the impedance matching is still lacking in the existing literature. A reasonable component composition and micro-structural design are very important for EMWA materials. In this work, through in situ pyrolysis of two polymetallic metal-organic frameworks (MOFs): CoMn-MOF and FeCoMn-MOF, Co and FeCo are subtly introduced into MnO@nanoporous carbon (NPC) composite to improve the permeability and the impedance matching, which leads to broadband EMWA performance. Co/MnO@NPC-8 has an effective absorption bandwidth (EAB; reflection loss ≤ −10 dB) of 5.44 GHz from 12.56 to 18 GHz at 1.58 mm-thickness. FeCo/MnO@NPC has an EAB of 7.72 GHz from 10.28 to 18 GHz at 1.63 mm-thickness, and when the thickness is 2.37 mm, the reflection loss reaches −54.07 dB. The excellent broadband EMWA performances of the corn-like composites are attributed to the conductive network of carbon matrix, the optimized dielectric constant provided by MnO, the dramatically enhanced permeability due to the dispersed Co and FeCo, and the multi-polarization loss among multiple components. Overall, this work provides an effective strategy to improve the impedance matching and broaden the EAB of absorbers.