Heterogeneous rod-like Ni@C composites toward strong and stable microwave absorption performance

Intrinsic physical property and unique nanostructures of microwave absorbing materials play an important role in their electromagnetic energy conversion. One-dimensional microstructure has been considered as an idea structure for microwave absorbers. Herein, heterogeneous rod-like Ni@Carbon (Ni@C) composites were synthesized by a handy hydrothermal reaction and a subsequent calcination treatment. Morphology analysis indicated that the resultant nanorods are composed by carbon and uniformly dispersed Ni nanoparticles (NPs). The rod-like carbon-magnetic structure could be adequately regulated via hydrothermal synthesis, resulting in tunable nano-micro structure and electromagnetic parameters. Benefiting from the magnetic–dielectric synergetic effect, the appropriate calcination temperature could improve the electromagnetic energy loss. In addition, the polarizing effect between nickel and carbon is demonstrated by density functional theory calculation. Therefore, this rod-like Ni@C composite reveals a favorable microwave absorption. The Ni@C nanorods (NC-3) possess a minimum reflection loss (RLmin) of −58.7 dB with a thickness of 1.66 mm at 13.9 GHz and achieved an effective absorption bandwidth (EAB) of 4.4 GHz. Furthermore, the carbon matrix of Ni@C acts as protective layer for Ni NPs, which could provide stable microwave absorbing performance even after one year measurement. This work introduces a facile and versatile strategy to design rod-like carbon structure as high-efficiency and stable microwave absorbers.