Fabrication of porous graphene-Fe3O4 hybrid composites with outstanding microwave absorption performance

Graphene is a promising lightweight microwave absorption (MA) absorber, but the limited dielectric loss and nonmagnetic characteristic have impeded its further applications. Through the structure modification, porous (1–2.5   μm) graphene was successfully prepared via a simple pyrolysis process, and the minimum reflection loss (RL) value reached −48   dB at 9.8   GHz, which demonstrated that porous graphene (PG) showed outstanding MA performance than the ordinary graphene (OG). In order to strengthen the magnetic loss, and then boost the impedance matching, Fe 3 O 4 nanoparticles (∼10   nm) were deposited uniformly on the surface of PG via in situ precipitation to synthesize porous graphene-Fe 3 O 4 (PG-Fe 3 O 4 ) composites. It was found that the as-prepared PG-Fe 3 O 4 composites showed especially high MA performance, and the minimum RL of −53.0   dB was achieved at 5.4   GHz with the thickness of 6.1   mm. The absorption bandwidth of RL less than −10   dB was from 12.6 to 18.0   GHz (5.4   GHz) with a thin thickness of 2.7   mm. The excellent MA properties of PG-Fe 3 O 4 composites were the consequence of the perfect impedance matching, porous structure as well as the multi-polarization. These results demonstrated that the PG-Fe 3 O 4 composites with excellent MA properties and lightweight should be promising absorbers for practical applications.