Integrated Mechanical and Microwave-Absorbing Properties in the Graphene Oxide/Fe ₃ O ₄ Composite Hydrogel

To address the challenge of balancing mechanical strength and electromagnetic wave absorption in hydrogel-based absorbers, this study presents a strategy for fabricating graphene oxide (GO)/Fe 3 O 4 composite hydrogels with tunable and integrated performance. By systematically adjusting the content of aminated Fe 3 O 4 nanoparticles (Fe 3 O 4 –NH 2 ), we demonstrate that the mechanical properties and microwave absorption capability of the hydrogel can be synergistically enhanced. The optimized hydrogel, containing 0.2 wt % GO and 0.3 wt % Fe 3 O 4 –NH 2, forms a stable three-dimensional hydrogen-bonded network that simultaneously improves tensile strength, fracture strain, toughness, and compressive performance. This integrated structure also facilitates excellent impedance matching and combines multiple electromagnetic loss mechanisms including dielectric, magnetic, and interfacial polarization losses. Consequently, the hydrogel exhibits strong broadband microwave absorption, achieving a minimum reflection loss of −57.0 dB at a thickness of 2.06 mm and an effective absorption bandwidth of 6.4 GHz. This work offers an effective approach for developing flexible, mechanically robust, and high-performance microwave-absorbing materials suitable for advanced electromagnetic compatibility applications.