Biomass-based MnO2 composite for efficient microwave absorption performance: Strong interfacial polarization and electron transition effects

In this study, we explored the effectiveness of enhancing microwave absorption capabilities of biomass-derived porous carbon by introducing MnO 2 through thermochemical techniques. The results showed that the MnO 2 -C exhibited higher values in both the real and imaginary parts of the dielectric constant compared to the Control, indicating that the addition of MnO 2 significantly enhanced the energy storage and dissipation capabilities. Although the magnetic loss properties of the composite were relatively weak, the increase in conductive and dielectric losses compensated for this aspect. Moreover, the loading of MnO 2 optimized the dielectric losses and promoted the reconstruction of charge, enabling MnO 2 -C to demonstrate superior microwave absorption performance, particularly in the high-frequency range. This is attributed to the multiple polarization mechanisms present in MnO 2 -C, including interfacial and dipolar polarization, which play a crucial role in enhancing dielectric losses. Additionally, a multilevel porous structure significantly enhanced the scattering and reflection of microwaves, further improving the absorption effectiveness. Consequently, these characteristics contribute to the MnO 2 -C achieving a minimum reflection loss value of −46.2 dB and an expanded effective absorption bandwidth. Overall, the MnO 2 -C composite, with its optimized electromagnetic properties and complex microstructure, provides valuable insights for the development of new, highly efficient microwave absorption materials.