Microwave Absorbing Properties of Nickel-coated Graphene

Graphene sheets were prepared by using chemical reduction of a colloidal suspension of graphene oxide sheets in water. After hydrophilic treatment and chemical plating, a layer of nickel particles was uniformly coated on the surfaces of the graphene sheets. The morphologies of the pure graphene (GF) and Ni-coated graphene (NGF), nickel element content on the graphene surface and magnetic properties of the NGF were examined by SEM, EDX and VSM, respectively. The complex relative permittivity and permeability of the NGF absorber were measured by using a microwave network analyzer in the frequency range of 2-18 GHz. The reflection loss curves of the OF and NGF were calculated using computer simulation technique. It is found that in the frequency range of 2-18 GHz, with the increase of the matching thickness, the maximum absorbing peaks of the OF and NGF shift to lower frequency region, so OF and NGF are dielectric loss microwave absorption materials. When the matching thickness is 1 mm, the maximum absorption peak of the OF is -.5dB at about 7GHz. When the matching thickness is 1.5 mm, the maximum absorption peak of the NGF is -16.5dB at 9.25 GHz and the frequency region in which the maximum reflection loss is more than -10.0 dB is 9.5-14.6 GHz.