Multilayered graphene foam composites with a gradient distribution of Fe3O4 hollow microspheres for broadband microwave absorption

Three-dimensional (3D) graphene exhibits great potential for microwave absorption due to its ultra-light density, large specific surface area, good conductivity, and mechanical compressibility, integrating material and structural features across different scales to achieve high-efficiency broadband absorption remains a significant challenge. In this study, graphene foam (GF) anchored with different content of Fe 3 O 4 hollow microspheres was initially synthesized via a solvothermal method. Subsequently, multilayer microwave absorbing materials were designed using a genetic algorithm (GA) by combining various Fe 3 O 4 /GF composites with distinct electromagnetic parameters for broadband absorption performance. The as-fabricated multilayer composite possesses an impedance-gradient architecture and exhibits an ultrawide absorption bandwidth of 9.27 GHz at a matching thickness of 2.8 mm, thereby validating the GA design strategy. Moreover, radar cross-section (RCS) simulations demonstrate that the multilayer Fe 3 O 4 /GF composite with a thickness of 2.0 mm achieves a maximum RCS reduction of 48.64 dB m 2 at 10.61 GHz. This work presents an efficient approach for developing high-performance microwave absorbing materials with multilayer gradient structures.