Enhanced Electromagnetic Microwave Absorption Property of Peapod-like MnO@carbon Nanowires

Investigating lightweight electromagnetic microwave absorption materials is still urgent because of the issue related to the electromagnetic pollution or military defense. Our findings indicate that core–shell MnO@carbon nanowires (MnO@C NWs) achieve substantially enhanced microwave absorption, suggesting the suitable impedance matching induced by the synergetic effect between MnO and carbon. Furthermore, the peapod-like MnO@C NWs with internal void space can be facially synthesized by partial etching of core–shell MnO@C NWs. The peapod-like MnO@C NWs with internal voids/cavities exhibit dramatically enhanced electromagnetic microwave absorption property when the carbon content is about 64 wt %, a minimum reflection loss (RL) of −55 dB at 10 wt % loading was observed at 13.6 GHz, and the bandwidth of RL less than −10 dB (90% absorption) covers 6.2 GHz at the thickness of 2 mm. The excellent electromagnetic microwave absorption performance is superior to the most of MnOx/C composites in the literatures, which probably benefits from the dielectric polarization among conductive network structure between MnO and carbon, as well as the multiple reflection and absorption induced by internal void space. Our work is expected to pave an effective way to extend the electromagnetic microwave absorption performance of MnO/C composites through partial etching to create a void space.