Novel rGO/α-Fe2O3 composite hydrogel: synthesis, characterization and high performance of electromagnetic wave absorption

A novel 3D composite hydrogel composed of reduced graphene oxide nanosheets and α-Fe2O3 nanoparticles (rGO/α-Fe2O3) was synthesized via a two-step process in a solution phase technique. The experimental results show the composite has an interconnected 3D porous network with micrometer pores, and the α-Fe2O3 nanoparticles with the size of about 50–100 nm are uniformly dispersed onto the thin graphene nanosheets. The rGO/α-Fe2O3 composite hydrogel exhibits excellent microwave absorbability. Compared to a pristine reduced graphene oxide (rGO) hydrogel, the reported composite hydrogel has both wider and stronger wave absorption achieved in the frequency range of 1–18 GHz. The composite with a coating layer thickness of 5.0 mm exhibits a maximum absorption of −33.5 dB at 7.12 GHz and in particular, the product with a coating layer thickness of only 3.0 mm shows a bandwidth of 6.4 GHz (from a frequency of 10.8–17.2 GHz) corresponding to reflection loss at −10 dB. The excellent microwave absorption properties are ascribed to the improved impedance matching. Our findings pave a way to design and prepare lightweight and high performance electromagnetic wave absorption materials based on 3D graphene and other nanomaterials.