Nitrogen-doped Co-C/MWCNTs nanocomposites derived from bimetallic metal-organic frameworks for electromagnetic wave absorption in the X-band

Herein, the nitrogen-doped Co-C/MWCNTs (multi-walled carbon nanotubes) nanocomposites derived from bimetallic metal-organic frameworks (MOFs) were fabricated by a facile two-step method: firstly, MWCNTs were used as the templates to in-situ nucleation and growth of Co/Zn-MOFs particles and subsequently converted into the Co-C/MWCNTs nanocomposites by the pyrolysis reactions. The structure, compositions, micromorphology, magnetic properties, and electromagnetic parameters of the obtained nanocomposites were systematically investigated by variously analytical techniques. Results revealed that the bimetallic MOFs derived porous carbon nanocomposites showed obviously enhanced electromagnetic wave absorption properties compared with the monometallic. The Co-C/MWCNTs nanocomposite with addition of 12.5 mg of MWCNTs (S2) exhibited the optimal electromagnetic wave absorption performance. The minimum reflection loss (RLmin) achieved -50.0 dB with a thickness of 2.4 mm and effective absorption bandwidth (EAB, RL <= -10 dB) reached 4.3 GHz with a thin thickness of 1.8 mm at a low filler loading ratio of only 25 wt%. Moreover, the EAB (3.6 GHz, from 8.2 to 11.8 GHz) covered 86% of the X-band (8.2-12.4 GHz) with a thickness of 2.5 mm. Notably, the obtained nanocomposites showed the dual waveband absorption characteristic. Furthermore, the effects of additive amounts of MWCNTs and filler loading ratios on the EMW absorption properties were carefully explored. Besides, the possible EMW absorption mechanism was further proposed. Our results could be helpful for designing and developing novel MOFs-derived porous carbon nanocomposites as the high-performance EMW absorbers.