Self-catalyzed growth of Co–N codoped carbon nanotubes for advanced multi-heterointerface engineering in hierarchical carbonaceous microwave absorbers

Abstract

Recently, the rational construction of hierarchical multi-heterointerfaces microstructure is becoming an extremely attractive strategy to obtain lightweight and excellent metal–organic frameworks (MOFs) based electromagnetic wave (EMW) absorbing materials. Herein, hierarchical MOF derived Co–N codoped carbon nanotube modified carbon foam (Co-NC@CF) with multi-heterointerfaces was fabricated via simple in-situ growth of ZIF-67 MOFs nanosheets on the surface of three-dimensional (3D) melamine foam (MF), followed by a pyrolytic self-catalyzed process, where the nitrogenous organic linkers of ZIF-67 were successfully converted into Co nanoparticle encapsulated N-doped carbon nanotubes. In addition to the synergetic effect of dielectric − magnetic dual-loss mechanism, the hierarchical heterogeneous and porous structure of Co-NC@CF also shows good impedance matching, multiple polarization loss, and multiple reflection and scattering. Furthermore, the numerous N-doped atoms and defects are vitally important for the enhancement of interfacial/dipole polarization, thereby enhancing the EMW dissipation properties. As a result, the EMW absorption performance of the prepared Co-NC@CF can be effectively tuned by changing the temperature of pyrolytic autocatalytic Co–N codoped carbon nanotube (CNTs), and the Co-NC@CF calcinated at 800 °C (Co-NC@CF-800) displays the strongest EMW absorption capability with a minimum reflection loss (RL_min) value of − 51.56 dB at a thickness of 2.25 mm at 14.96 GHz with only 5 wt% filler loading, and the maximum effective absorption bandwidth (EAB_max) also reaches 6.88 GHz ranging from 11.12 to 18 GHz. These excellent electromagnetic properties can make Co-NC@CF eligible to be a great promising candidate for high-performance EMW absorbing materials, and this work will provide inspiration more or less for the design of hierarchical heterogeneous absorbing materials in the future.