Controlling the heterogeneous interfaces of Fe3O4/N-doped porous carbon via facile swelling for enhancing the electromagnetic wave absorption

Bio-derived carbon is considered to be an ideal lightweight electromagnetic waves (EMW) absorbing material. Herein, Fe3O4/N-doped porous carbon (N-Fe3O4@UHPC) is successfully prepared through simple swelling-freeze drying and pyrolysis. The method can introduce evenly distributed Fe3O4 and porous structure into the carbon, which can effectively improve the impedance matching and multiple reflection and scattering of EMW. N-Fe3O4@UHPC-4 exhibits superior electromagnetic wave absorption performance with the minimum reflection loss value of -77.91 dB at 17.21 GHz. Besides, the optimum effective absorption broadband value of N-Fe3O4@UHPC-2 is up to 8.49 GHz from 9.51 to 18 GHz at 3.0 mm, which almost cover the whole X band and Ku band. The excellent EMW performance of N-Fe3O4@UHPC is attributed to the interface polarization, dipole polarization, natural resonance, eddy current, exchange resonance, and the conductive network formed.