Graphite encapsulated ZIF-67 derivatives with carbon nanotubes immobilized on carbon aerogels toward superior microwave absorption

Abstract

Exploring the synergistic effects of components and structures has emerged as a pivotal strategy for advancing high-performance electromagnetic wave (EMW) absorbing materials. In this work, we present an approach that integrates magnetic-dielectric components and porous structures by incorporating unidirectionally frozen-drying aramid nanofiber aerogels with ZIF-67 and subsequently preparing Co/Co₃O₄@carbon nanotubes/carbon nanofibers aerogels through heat treatment and catalyst chemical vapor deposition. By combining different functional components, a multiple heterostructure with excellent absorption capacity, wide effective absorption bandwidth (EAB), and thin thickness can be achieved. The inclusion of the magnetic-dielectric component significantly enhances the impedance matching, generating multiple loss mechanisms. Additionally, the three-dimensional porous structure of the aerogel facilitates multiple reflections and scattering of the incident EMWs, thereby enhancing the microwave absorption. Specifically, the obtained samples exhibit outstanding EMW performance, with a minimum reflection loss of −73.50 dB at a thickness of merely 2.08 mm and an EAB of 5.90 GHz. Furthermore, simulations evaluating radar cross-section values, electric field strengths, and energy loss density are conducted to assess the stealth capabilities under radar detection. This study culminates in the preparation of an aerogel characterized by excellent wave-absorbing properties and effective thermal insulation, offering vast potential for practical applications.