Nanoconfined Magnetic Network Constructed by a NiCo Alloy Doped Interconnected Carbon Nanotube toward Enhanced Electromagnetic Wave Absorption Performance

Metal–organic framework (MOF)-derived magnetic metal/carbon nanocomposites have evolved as prospective functional materials with application in the electromagnetic wave (EMW) absorption field due to their tailorable dielectric–magnetic characteristic. Nonetheless, a significant challenge remains in regulating the microstructure of MOF-derived nanomaterials to acquire excellent EMW absorption. Herein, NiCo alloy and N-doped bamboo-like carbon nanotube network (NiCo@CNTs/NC) magnetic–dielectric composites were fabricated using a one-dimensional (1D) NiCo-MOF nanobelt as precursor through a one-step melamine-assisted pyrolyzing process. The interconnected carbon nanotube network structure offers multiple electronic migration and hop paths and effectively facilitates conductive loss. The adjustable Ni/Co nodes in the 1D MOFs were effectively transformed into NiCo alloy nanoparticles and confined within the tips of the in situ-generated interconnected CNT networks. Such well-dispersed and nanoconfined magnetic NiCo nanoparticles generate a nanoscale magnetic coupling network and provide a high density of polarized sites, reinforcing the magnetic–dielectric coupling ability as well as triggering interfacial polarization. Consequently, the optimized NiCo@CNTs/NC-20/1 composite achieves glorious EMW absorption with a strong reflection loss (RLmax) of −30.31 dB at only 1.4 mm thickness and an effective absorption bandwidth as wide as 4.5 GHz at 1.6 mm thickness when the filling fraction is 20 wt %. Considering the excellent EMW absorption properties, we believe that this work will provide new insights into the design of magnetic metal/carbon nanocomposites that enhance EMW absorption properties through the reasonable construction of low-dimensional interconnected magnetic–dielectric networks with magnetic nanoparticles in nanoconfined spaces.