Heterogeneous iron-nickel compound/RGO composites with tunable microwave absorption frequency and ultralow filler loading.

We fabricated heterogeneous iron-nickel compound/reduced graphene oxide (RGO) composites to obtain lightweight and high-efficiency microwave absorption materials with tunable absorption frequency. Using a facile hydrothermal route in combination with calcination at varying temperatures of 500-700 °C, the magnetic components Fe0.64Ni0.36, Fe0.64Ni0.36@Fe2Ni2N, and Fe2Ni2N were obtained. Due to strong interfacial polarization and dipole polarization as well as the conductive network formed by the substantial number of interfaces, all the magnetic RGO hybrids presented remarkable electromagnetic wave attenuation ability even when the filler content was only 5.2 wt%. More importantly, the optimization of reflection loss and tunable absorption frequency could be successfully realized by tuning the hybrid architecture and electromagnetic properties. This work reveals the mechanism of polarization-related dielectric relaxation of RGO, which provides new opportunities for designing lightweight and highly efficient microwave-absorbing materials by fully utilizing the hetero-interfacial effects.