Synthesis and microwave absorption properties of nickel nanoparticles-graphene composites with different morphologies

Nickel nanoparticles-graphene (Ni-GNs) composites with two different morphologies were successfully synthesized by in situ chemical reduction, and the morphology-dependent electromagnetic absorption properties of the composites was investigated. By changing the sequence of the reactants are added during preparation, spherical and spinous spherical nickel nanoparticle-graphene composites were obtained. The structure, morphology, and microwave absorption properties of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vector network analysis (VNA). The results indicated that the spinous spherical nickel nanoparticle-graphene composites had better microwave absorption ability than the spherical nickel nanoparticle-graphene composites. This is due to the unique isotropic antenna morphology of the spinous spherical nickel nanoparticles in the composites, arising from the point discharge effect. This facile in situ chemical reduction method for the preparation of nickel nanoparticle-graphene composites to give different morphologies could be used for the preparation of other composites.