Ultrasound-assisted freeze-drying graphitization process for the fabrication of two-dimensional carbon/Fe3O4 composite aerogels for microwave absorption

Abstract

Magnetic Fe3O4 materials have received attention from researchers due to their significant wave absorption potential, but there are limitations to their efficient electromagnetic wave absorption and lightweight applications. Combining materials with dielectric properties to optimize the performance of Fe3O4 has become one of the research directions. In particular, carbon nanomaterials, such as graphene, show great application prospects in the field of microwave absorption due to their physical properties. To improve the impedance mismatch issue of graphene, researchers consider combining it with magnetic nanoparticles. Commercial applications require materials that are cost-effective, easy to produce, and environmentally sustainable, driving research on novel 2D carbon materials. In this study, 2D carbon materials were prepared by ultrasound-assisted freeze-drying/graphitization process using polymers as precursors, which simplifies the preparation process and avoids the use of expensive sacrificial templates and catalysts. The 2D carbon materials prepared by this method were used as the dielectric component in the wave-absorbing composites, and the nano effect was utilized to significantly improve the microwave absorption properties of the materials. The maximum reflection loss of the prepared graphite nano-aerogel reaches −84.16 dB and the EAB reaches 3.74 GHz. In addition, by adding Fe3O4 nanoparticles and applying an ultrasonic field for dispersion in the freeze-drying process, the nanoparticle agglomeration is effectively prevented, which provides a simple and efficient pathway for the preparation of nanocomposites.