Controllable and lightweight ZIF-67@PAN derived Co@C nanocomposites with tunable and broadband microwave absorption

Metal-organic framework-based carbon–carbon composite represent a novel class of microwave-absorbing materials (MAMs). However, obtaining lightweight and highly efficient absorbers with a lower filling ratio and larger effective absorption bandwidth (EAB) poses a challenge. In this study, we developed a controllable preparation method for ZIF-67 template polyacrylonitrile-wrapped nanocomposite (ZIF-67@PAN) precursor. This was achieved through radical polymerization of acrylonitrile (AN) initiated by azobisisobutyronitrile (AIBN). Subsequent annealing at high temperatures produced a lightweight nitrogen and oxygen-doped graphite layer-wrapped Co@C smart material (Co@C₁, Co@C₂, and Co@C₃) with tunable microwave absorption properties (MAP). The results demonstrate that Co@C₂ achieved a minimum reflection loss (RL_min) value of −50.20 dB at a thickness of 2.0 mm with an EAB of 6.1 only at a filler content of only 13 %. Therefore, this work offers a controllable preparation method and introduces a simple and facile approach for creating efficient, lightweight micro and nano-sized microwave-absorbing materials.