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

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 degrees C (Co-NC@CF-800) displays the strongest EMW absorption capability with a minimum reflection loss (RLmin) 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 (EABmax) 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.