Microwave-assisted synthesis of graphene–Ni composites with enhanced microwave absorption properties in Ku-band

Abstract

Recently, graphene has been applied as a new microwave absorber because of its high dielectric loss and low density. Nevertheless, the high dielectric constant of pristine graphene has caused unbalanced electromagnetic parameters and results in a bad impedance matching characteristic. In this study, we report a facile microwave-assisted heating approach to produce reduced graphene oxide–nickel (RGO–Ni) composites. The phase and morphology of as-synthesized RGO–Ni composites are characterized by XRD, Raman, FESEM and TEM . The results show that Ni nanoparticles with a diameter around 20 nm are grown densely and uniformly on the RGO sheets. In addition, enhanced microwave absorption properties in Ku-band of RGO–Ni composites is mainly due to the synergistic effect of dielectric loss and magnetic loss and the dramatically electron polarizations caused by the formation of large conductive network. The minimum reflection loss of RGO–Ni-2 composite with the thickness of 2 mm can reaches −42 dB at 17.6 GHz. The RGO–Ni composite is an attractive candidate for the new type of high performance microwave absorbing material. • Ni nanoparticles are grown densely and uniformly on the RGO sheets via microwave-assisted heating approach. • Ni resistance effect is proposed to explain the mechanism to decrease the permittivity with the rising combination of Ni and RGO. • The microwave absorption properties in Ku-band of RGO–Ni composites are effectively enhanced. • The mechanism to improve the microwave absorption properties is discussed.