In the current work, we synthesized Ni/C composites from Ni/cellulose composites and analyzed how well the products absorbed microwaves. The Ni/C composite products showed a maximal reflection loss (RL) of −53.8 dB at 4.72 GHz with a sample thickness of 4.5 mm, and the RL values exceeded −10 dB covers almost the whole tested frequency ranges (2–18 GHz). These results were attributed to a combination of the magnetic loss and the dielectric loss. This work is expected to contribute to the development of materials that absorb a broad region of the electromagnetic wave and to the recycling of cellulose.

•GO and Ni2+ were reduced simultaneously during the reduction process.•The Ni/RGO nanocomposites exhibits enhanced EM absorption performance.•The impedance matching and interfacial polarization could be obtained.•This work provides a typical sample with enhanced electromagnetism.In this work, Ni/reduced graphene oxide (RGO) nanocomposites were prepared via an in-situ reduction step. During the reduction process, graphene oxide (GO) and Ni2+ ions were reduced simultaneously and consequently, the magnetic Ni nanoparticles were dispersed in nonmagnetic RGO matrix homogeneously. Combining the cooperative effect from RGO and Ni, the as-fabricated Ni/RGO composites exhibit enhanced EM absorption performance as compared to the individual compositions due to the improvement of the electromagnetic loss performance and the enhanced electromagnetic impedance matching.