Anchoring porous carbon nanoparticles on carbon nanotubes as a high-performance composite with a unique core-sheath structure for electromagnetic pollution precaution

Abstract

Carbon/carbon composites are becoming promising functional materials with wide applications in many fields. Although they are always considered as qualified candidates for lightweight and durable microwave absorbing materials (MAMs), their electromagnetic (EM) performance still suffers from the imbalance between characteristic impedance and loss capability. With carbon nanotubes (CNTs) as the scaffold, we herein direct the in situ growth of ZIF-8 nanocrystals on their surface and then convert the intermediate into porous carbon nanoparticles/CNTs (PCNs/CNTs) composites with a unique core-sheath structure. Interestingly, the combination of PCNs and CNTs create a positive synergistic effect on the overall EM properties. On the one hand, graphitic CNTs can maintain their powerful intrinsic loss toward incident EM waves, and on the other hand, amorphous PCNs closely anchored on CNTs can regulate the impedance matching effectively and bring sufficient interfacial polarization that is favorable for the consumption of EM energy. By manipulating the relative contents of PCNs and CNTs, the optimal PCNs/CNTs composite produces excellent EM absorption performance, whose strongest reflection loss can reach up to −71.5 dB with the absorber thickness of only 1.1 mm and the integrated effective absorption bandwidth is as broad as 15.1 GHz. Such a performance is superior to those of most of the reported carbon/carbon composites. These results indicate that a precise design of the configuration of carbon/carbon composites will be a valid way to develop novel and high-performance MAMs.