Fe₃O₄-decorated single-walled carbon nanohorns with extraordinary microwave absorption property

Single-walled carbon nanohorns (SWCNHs) are seldom used as electromagnetic (EM) wave absorption materials due to their inferior impedance matching resulting from their high dielectric constant. In this work, decorated with 35.6 wt% Fe₃O₄ nanoparticles, the as-prepared composite displays a significantly enhanced EM wave absorption ability because of the improved impedance matching, electric polarization and interfacial polarization. Specifically, the maximum reflection loss of this composite with a thickness of 5.8 mm is -38.84 dB at 3.72 GHz in the S-band. The bandwidth of absorption exceeding -10 dB is 9.2 GHz (from 3.2 GHz to 12.4 GHz) with an absorber thickness of 2-6 mm. What is more, a second absorption peak with a reflection loss no less than -10 dB appears when the absorber thickness is over 4 mm.