Electromagnetic properties and microwave absorption enhancement mechanism of graphene-regulated Fe-Co-Zn-O@C composites

Abstract

With the rapid development of high-frequency electronic technology, pollution caused by electromagnetic radiation has grown more serious. Consequently, creating high-performance microwave absorbing materials featuring “light weight, thin thickness, broad bandwidth, and strong attenuation” has emerged as a major area of interest. In this work, a ternary Fe-Co-Zn-O (FCZO) oxide precursor was synthesized via a sol-gel technique. Subsequently coated it with an epoxy resin, and then subjected to an oxygen-free carbonization process to construct a carbon shell, ultimately yielding Fe-Co-Zn-O@C (FCZO@C) core-shell composite materials. By systematically tuning the graphene content, the influence on the microwave absorption performance and the underlying electromagnetic loss mechanisms of the composites was thoroughly investigated. Findings indicate that with 1.5 wt% graphene, the polylactic acid (PLA)-based FCZO@C-GR/PLA-3 composite reaches an effective absorption bandwidth (EAB) of 5.34 GHz (12.66–18.00 GHz) at a matching thickness of merely 1.95 mm. When the graphene content reaches 2.5 wt%, the FCZO@C-GR/PLA-5 sample achieves a minimum reflection loss (RL min ) of −47.45 dB at an even thinner 1.42 mm, showing excellent microwave absorption capability. This study offers fresh perspectives on the structural design and performance regulation of carbon-based magnetic multicomponent composites, and offers theoretical and experimental foundations for the controllable preparation of highly efficient, lightweight and eco-friendly microwave absorbing materials.