Cobalt nanoparticles decorated on nitrogen-doped graphene as excellent electromagnetic wave absorbent in Ku-band

Carbon-based magnetic composites with enhanced electromagnetic (EM) wave absorption ability have received intensive attention. Herein, a composite of N-graphene and small size magnetic Co nanoparticles (NPs) with advantages of excellent dielectric ability was synthesized through an in situ grown method. Under optimized conditions, Co NPs decorated on NGN (Co/NGN-2) have the best EM wave absorption performance, of which a minimum reflection loss of - 45.8 dB can be achieved at 13.48 GHz with a thin coating of 2 mm at 15 wt% filler loading in paraffin wax. The effective absorption bandwidth is about 4.6 GHz in Ku-band (12.4-18 GHz). Importantly, the effective absorption bandwidth can be extended by changing the thickness of the absorber. In fact, the coupling of NGN with Co NPs can form an effective impedance match, and thus the small size Co NPs with low density and good performance decorated on NGN material make the present method promising for EM applications.