Bimetallic MOF-derived CoZn-C/MWCNTs composite for lightweight and wideband microwave absorption

Achieving high-performance microwave absorbers characterized by wide bandwidth, robust absorption, lightweight properties, and thin profiles remains a critical challenge within modern radar stealth and electromagnetic compatibility domains. In this study, we introduce a straightforward and cost-effective strategy for fabricating lightweight and efficient microwave absorbers utilizing composites derived from bimetallic zeolitic imidazolate frameworks (ZIFs). A variety of ZIF-8@ZIF-67 precursors incorporating multi-walled carbon nanotubes (MWCNTs) were synthesized through a sequential wet-chemical process. These precursors underwent conversion into porous bimetallic MOF-derived CoZn-C/MWCNTs composites via subsequent pyrolysis. The composition, microstructure, and electromagnetic characteristics of the pyrolyzed materials were precisely regulated by varying the Co/Zn molar ratio within the precursors. Due to the synergistic magnetic and dielectric dissipations, the 3:1 Co/Zn composite exhibited the best attenuation constant and impedance matching among all synthesized samples. Thus, the optimized composite provided a significant effective absorption bandwidth of 5.29 GHz at a thickness of 1.9 mm, coupled with an outstanding minimum reflection loss of −23.78 dB at 2.0 mm, even with a minimal filler loading of 20 wt%. The enhanced scattering suppression behavior was additionally verified through radar cross-section simulation. This research provides a novel viewpoint on the rational design of lightweight MOF-based composites for broadband electromagnetic wave absorption performance.