Low-temperature carbonization MOF/CNF aerogel for high-performance microwave absorption and thermal camouflage

Abstract

Developing lightweight, high-performance microwave absorbing materials with multiple functions has become a major challenge in the field of electromagnetic protection. In this study, ZIF-67/cellulose nanofiber (CNF)-derived Co–C/C aerogel with an integrated design for microwave absorption and thermal camouflage functions was prepared. The hierarchical pore structure with coexisting micron-scale skeletal pores and MOF-derived nanopores was constructed through in-situ growth of ZIF-67 on CNF and low-temperature carbonization regulation. Simultaneously, uniformly distributed Co nanoparticles (20–30 nm) and defect-rich graphitized carbon heterointerfaces were obtained. The Co–C/C aerogel exhibited an ultra-low density (16.21–17.35 mg/cm³). In terms of microwave absorption, it achieved an effective absorption bandwidth of 6.87 GHz (covering the Ku band) at a thickness of 2.4 mm. This was attributed to the synergistic mechanisms of multiple scattering from hierarchical pores, enhanced interfacial polarization induced by low-temperature carbonization, and magnetic loss from Co nanoparticles. In addition, the material demonstrated a low thermal conductivity of 0.0492 W m⁻¹ K⁻¹, and infrared imaging revealed its significant thermal signal shielding capability. This study addressed the issues of structural collapse and functional singleness in traditional MOF-derived materials through in-situ growth and low-temperature carbonization strategies, providing new insights for the design of lightweight, broadband, and multifunctional stealth materials.