▎ 摘　　要

The development of graphene-based magnetic composites with strong absorption, wide bandwidth and thin thickness remains a great challenge. In this work, nitrogen-doped reduced graphene oxide/copper-nickel ferrite (NRGO/Cu0.5Ni0.5Fe2O4) composite was fabricated via a one-step hydrothermal process. Results demonstrated that the microscopic morphology and electromagnetic (EM) absorbing performance of as-synthesized magnetic composites were greatly influenced by the type and composition of spinel ferrites. Significantly, the attained NRGO/Cu0.5Ni0.5Fe2O4 composite showed a good dispersion of particles, and a large number of tetragonal Cu0.5Ni0.5Fe2O4 nanoparticles were almost homogeneously loaded on the rippled and wrinkled surfaces of lamellar NRGO. Compared with NRGO/CuFe2O4 and NRGO/NiFe2O4 composites, the NRGO/Cu0.5Ni0.5Fe2O4 composite presented the notably enhanced EM absorbing performance. It was noteworthy that the optimal minimum reflection loss reached up to - 67.4 dB and maximum effective absorption bandwidth achieved 4.7 GHz under a very thin matching thickness of 1.7 mm and a filler loading content of 50 wt%. Furthermore, the possible EM dissipation mechanism had been proposed. The results of this work would provide a reference for the development of RGO-based composites as thin and high-performance EM wave absorbers.