Rational design of lightweight microwave absorbers: synergistic dielectric-magnetic loss in 3D hierarchical graphene/Fe3O4 microflower composites

Abstract

The escalating challenge of electromagnetic pollution demands high-performance microwave absorbers that overcome the typical limitations of narrow bandwidth, high density, and poor impedance matching. Here, we present a rational design of three-dimensional reduced graphene oxide (RGO)/Fe₃O₄ microflower composites via a combined solvothermal, freeze-drying, and thermal treatment process. The optimal composite achieves exceptional microwave absorption with a minimum reflection loss (RL) of −63.2 dB at 2.7 mm and an effective absorption bandwidth (RL ≤ −10 dB) of 6.89 GHz at an ultralow filler loading of 8.0 wt%. This outstanding performance arises from the synergistic integration of dielectric and magnetic losses, optimized impedance matching, and enhanced interfacial polarization within the three-dimensional porous graphene aerogel architecture embedded with Fe₃O₄ microflowers, which effectively suppresses graphene restacking and promotes multiple scattering of incident waves. This work demonstrates an effective strategy for developing lightweight, high-efficiency absorbers through tailored compositional and structural engineering.