Controlled self-assembled FeNi alloy/graphene foam composite for lightweight and broadband microwave absorption

The search for lightweight and broadband microwave absorbing materials (MAMs) is crucial to fulfill the demands of practical applications. Herein, an FeNi alloy/graphene foam (FNGF) composite was prepared by a facile one-step hydrothermal method. The microwave-absorbing properties of the FNGF with varying concentrations of FeNi alloy (samples designated as 1#, 2#, 3#, 4#, and 5#) were systematically studied. Remarkably, with an ultra-low filling content of 5 wt%, the composite still achieves excellent microwave absorbing performance. As expected, the effective absorption bandwidth of sample 1# covers the entire Ku band (11.76–18 GHz) at a thickness of only 2.09 mm, and sample 3# reaches a minimum reflection loss of −63.76 dB at 15.68 GHz. FeNi alloys have a significant influence on the microscopic morphology, phase structure, and electromagnetic properties of composites. The superior MA properties can be attributed to the synergistic effect of superior impedance matching, robust dielectric loss, and magnetic loss. Notably, FNGF presents as a promising candidate for lightweight broadband MAMs.