MOFs derived multi-scale lamellar network for broadband electromagnetic wave absorber

Abstract

Developing an efficient EM wave absorbing material that can broadband absorb EM waves in a wide thickness range is a significant challenge. Herein, we report a multi-scale heterogeneous Co/C composite foam with a three-dimensional (3D) lamellar network to address this challenge. The internal structure of melamine foam (MF) is engineered via carboxymethyl cellulose (CMC) in-situ lamella formation to guarantee excellent impedance matching. Meanwhile, the CMC lamellar network extends the EM wave transmission path. The MOF-derived particles grow uniformly in the lamellar network, covering channels of EM wave transmission, which significantly enriches the EM wave loss mechanism and enhances attenuation capability. Benefiting from the synergistic effect of the 3D lamellar network and multi-scale heterogeneous carbon source, an EM absorber strikes a balance between impedance matching and absorption efficiency. As a result, Co/C@MC delivers an effective absorption bandwidth (EAB) that is more than 8 GHz in the whole range of thicknesses from 3.5 to 8 mm, Ni/C@MC exhibits an EAB of 8.5 GHz at 3.3 mm and Fe/C@MC shows the optimal reflection loss of −76.9 dB at 2.5 mm. This work provides a lamellar network/regional enhancement unit strategy for preparing ultra-efficient broadband EM wave absorbing materials.