Metal−organic framework (MOF)-derived magnetic porous carbon not only have excellent magnetic loss, but also can construct various nanostructures through appropriate design to enhance electromagnetic waves (EMWs) absorption. Herein, magnetic porous carbon (Co/Ni@C) derived from rod-shaped Co/Ni-MOFs was selected as magnetic components and MXene was regarded as conductive materials to construct the three-dimensional porous Co/Ni@C/MXene/cellulose-derived carbon foams via a simple solution mixing-regeneration, freeze-drying process and a facile pyrolysis strategy. Due to the electric/magnetic coupling loss and the interfacial polarization loss caused by multi-interface architecture, the synthesized carbon foam achieves an absorption coefficient of 0.54 and a high EMI SE of 70.4 dB, which enhances the electromagnetic shielding performance without damaging the high absorption coefficient. This work provides a basis for the preparation of electromagnetic shielding composite materials with multi-interface structures to achieve efficient EMI SE and superior absorption coefficients.
Metal–organic frameworks (MOFs) exhibit highly adjustable porosity, structure, and versatility, properties that render them promising for electromagnetic wave (EMW) absorption applications. However, the impedance matching of these composites is poor in practical applications, thereby compromising their EMW absorption performance. In this study, a novel EMW absorbing composite was synthesized by a solution-thermal method combined with a subsequent pyrolysis process. Specifically, we introduced heteroatom (N and S) codoped graphene (N, S-Gr) into the Co–Ni MOF, forming N, S-Gr/CoNi/C. Graphene was endowed with abundant defect and disorder sites through the codoping of nitrogen and sulfur, which enhanced interfacial polarization and dipole polarization. When nickel and cobalt were added in a 1:1 ratio, the minimum reflection loss (RLmin) of the N, S-Gr/Co–Ni/C composite reached −47.7 dB at 4.24 GHz, and the resultant material exhibited the best absorption properties. As a result, this composite is considered to be an ideal candidate for the development of highly effective EMW absorbers.
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