Super broadband absorbing hierarchical CoFe alloy/porous carbon@carbon nanotubes nanocomposites derived from metal-organic frameworks

The exploitation of electromagnetic wave absorption (EMA) materials has attracted ever-increasing attention, not only because electromagnetic wave (EMW) originated from overuse of electronic products has threatened human' health seriously, but also because EMA materials can effectively protect radar stealth from being detected. However, it is still a challenge to obtain broadband and efficient EMA materials to satisfy practical applications. In this work, we developed a series of hierarchical CoFe alloy/porous carbon@carbon nanotubes (CoFe/PC@CNTs) nanocomposites through revising the proportion of Fe2+ in the metal-organic frameworks (MOFs) (CoFe-ZIF) precursor and one-step simple pyrolysis process. The cross deposition between CoFe alloy, carbon nanotubes (CNTs), and porous carbon (PC) formed a double conductive network, favoring for achieving excellent EMA property. Surprisingly, when the filler mass ratio is only 10 wt%, the optimized CoFe/PC@CNTs nanocomposites display the best EMA capability, whose minimum reflection loss (RLmin) value is -68.94 dB at 13.69 GHz and the effective absorption band (EAB, < -10 dB) reaches up 9.14 GHz with a matching thickness of 2.63 mm. In addition, the largest EAB can achieve up to 11 GHz (3.35-14.35 GHz) during all matching thicknesses. The splendid EMA performance benefits the favorable dielectric loss provided by the double conductive network, the good magnetic loss benefited from the evenly distributed CoFe alloy, the excellent impedance matching, rich transmission paths, and multiple polarization. Therefore, such EMA materials with super broadband absorbing provide desirable candidates for lightweight and high-efficient microwave absorbers. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.