Synergistic impacts of Fe/Fe3C and Fe-Nx on high-efficiency microwave-absorbing properties of Fe/Fe3C@NC composites.

The construction of multi-component composites has become an attractive strategy for high-performance microwave absorption through balancing the magnetic and dielectric loss. However, the influences of different components on absorption performance are ambiguous, which has inevitably hampered the widespread applications of microwave absorbents. Herein, we rationally designed the multi-component absorbers of N-doped carbon composited with Fe/Fe3C nanoparticles, and systematically investigate the impacts of Fe/Fe3C nanoparticles and Fe-Nx moieties on the microwave-absorbing capacities. It is found that the coexisitence of Fe/Fe3C and Fe-Nx is indispensable to realize the strong microwave absorption ability by simultaneously enhancing the dielectric and magnetic loss in the frequency range of 2-18 GHz. As expected, our optimal absorber dispersed in paraffin with a filler loading of 15 wt% exhibits the minimum reflection loss (RLmin) value of -49 dB and the maximum effective absorption bandwidth (BWeff) value of 4.2 GHz at a low thickness. Our work specifies the importance and influence of the coexistence between the Fe-Nx configurations and Fe/Fe3C nanoparticles in the carbon-based composites for the superior microwave absorption and inspires the future fabrication of extraordinary materials in the electromagnetic field.