One-dimensional well-defined peapod Co_xNi_y@C nanocomposite hollow nanorod towards enhanced electromagnetic performance

Microwave absorbing materials (MAMs) not only achieve high electromagnetic absorption, but also have the characteristics of lightweight and oxidation resistance. This is a problem that needs to be solved urgently in some special fields. Therefore, we have done a series of experiments and prepared one-dimensional pea pod-like Co_xNi_y@C absorbing material. Through the experimental results and previous work, we find that one-dimensional structure has great potential to achieve high absorption efficiency and lightweight, and can achieve good impedance matching at low filling rate, which is attributed to the enhancement of conductivity of one-dimensional structure and the interface polarization caused by core-shell structure, and the one-dimensional structure will further increase the heterogeneous interface area and enhance the interface polarization loss. The minimum reflection loss (RL_min) and effective absorption width (EABD) of a series of pea pod-like Co_xNi_y@C were − 48.4 dB and 4.8 GHz for Co₂Ni₁@C (12.3 GHz, 2.2 mm), and-43.2 dB and 5.8 GHz for Co₃Ni₁@C (9.5 GHz, 2.1 mm). Because of the addition of Ni, the formed NiO layer protects the alloy particles, which makes Co_xNi_y@C have certain oxidation resistance. After being oxidized at 350 ℃ for 12 h in air, the RL_min and EABD of Co_xNi_y@C remained at -41.2 dB and 5 GHz, respectively. This work shows the important potential of one-dimensional structure in lightweight of MAMs, and provides valuable insights for the subsequent research on oxidation resistance of MAMs.