Preparation and tunable microwave absorption capacities of tubular NiFe@CN nanocomposites via a self-sacrificed template of NiFe Prussian blue analogs

Magnetic metal/carbon composites derived from metal–organic frameworks (MOFs) are viewed as promising candidates for high-performance microwave absorbers. Despite progress, a persistent challenge remains in expanding the effective absorption bandwidth (EAB) for microwave absorbers based on MOFs. To solve the above problems, in this work, NiFe@CN nanocomposite consisting of nickel–iron alloy nanoparticles (NiFe alloy NPs) embedded into nitrogen-doped carbon nanotubes (NCNTs) were fabricated utilizing a flexible two-step method, including co-precipitation and chemical vapor deposition, where the synthesized precursor NiFe Prussian blue analogs (NiFe-PBA) served as the self-sacrificed template and dicyandiamide (DCDA) served as carbon source. By tailoring the mass ratio of DCDA to NiFe-PBA, the morphology of synthesized NiFe@CN nanocomposites can be precisely controlled to create more tubular structures. These structure features enable NiFe@CN nanocomposites to acquire a synergistic effect of interfacial polarization, defect dipole polarization, conduction loss, eddy current loss, and magnetic resonance, which leads to enhanced dielectric loss, optimized impedance matching, and intense attenuation capability. As a result, the NiFe@CN nanocomposites exhibit excellent microwave absorption performance. At a thickness of 2.04 mm, the minimum reflection loss (RL min ) is − 54.09 dB at 13.41 GHz, and the EAB is 5.78 GHz. This work presents a novel strategy for designing low-cost, lightweight, and broadband frequencies microwave absorbers derived from bimetallic MOFs.