Tailoring Microwave-Absorption Properties of Co x Ni y Alloy/RGO Nanocomposites with Tunable Atomic Ratios

Co (x) Ni (y) nanoparticles anchored on reduced graphene oxide (rGO) composites with different Co(0)/Ni(0) ratios were successfully prepared by a simple hydrothermal method. The morphology, structure, and magnetic and microwave electromagnetic properties of Co (x) Ni (y) /rGO composites were characterized by the x-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, Raman spectroscopy and a vector network analyzer. The Co (x) Ni (y) /rGO composites exhibited enhanced microwave absorption properties, which are attributed to the effective complementarities between dielectric loss and magnetic loss. For the Co3Ni1/rGO composite, the minimum reflection loss (RLmin) is -44.89 dB at 12.22 GHz with absorber thickness of 2.5 mm, and the effective absorption bandwidth of the reflection loss (RL) <-10 dB (indicating 90% attenuation) could achieve 5.61 GHz. It is believed that the Co3Ni1/rGO composite may be a promising candidate as a microwave absorber with the features of low density, strong absorption, wide band and low thickness.