Designing flower-like MOFs-derived N-doped carbon nanotubes encapsulated magnetic NiCo composites with multi-heterointerfaces for efficient electromagnetic wave absorption

By controlling the Ni/Co ratio in precursor, the microstructure of MOFs with tunable morphology are obtained. The derived N-doped carbon nanotubes tightly connect the adjacent nanosheets to construct the special 3D interconnected conductive network, which effectively accelerates the charge transfer and improves the conduction loss. The flower-like microstructure allows more electromagnetic waves to enter the absorber, which is conducive to improving impedance matching, extending the transmission path of electromagnetic waves, and thus losing electromagnetic energy. In addition, the uniformly dispersed CoNi nanoparticles are conducive to improving the magnetic coupling strength, and the resulting heterogeneous interface enhances the interface polarization. [Display omitted] In order to acquire exceptional electromagnetic wave absorption properties, the microstructure design and component modification of composites are essential. Metal-organic frameworks (MOFs), due to the unique metal–organic crystalline coordination, tunable morphology, high surface area, and well-defined pores, have been regarded as promising electromagnetic wave absorption materials precursors. However, the inadequate contact abilities between adjacent MOFs nanoparticles endow it with undesirable electromagnetic wave dissipation capacity at a low filler loading, which is a great challenge to break size effect of nanoparticles to achieve efficient absorption. Herein, NiCo-MOFs derived N-doped carbon nanotubes encapsulated with NiCo nanoparticles anchored on flowers-like composites (denoted as NCNT/NiCo/C) were successfully prepared through facile hydrothermal method followed by thermal chemical vapor deposition with melamine-assisted catalyst. By controlling the Ni/Co ratio in precursor, the tunable morphology and microstructure of MOFs are achieved. Most importantly, the derived N-doped carbon nanotubes tightly connect the adjacent nanosheets to construct the special 3D interconnected conductive network, which effectively accelerates the charge transfer and improves the conduction loss. And notably, the NCNT/NiCo/C composite delivers excellent electromagnetic wave absorption performance with minimum reflection loss of −66.1 dB and wide effective absorption bandwidth up to 4.64 GHz when the Ni/Co ratio is 1:1. This work provides a novel method for the preparation of morphology controllable MOFs-derived composites and realizes high-performance electromagnetic wave absorption properties.