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

• Published in: Journal of environmental chemical engineering 2024-12, Vol.12 (6), p.114667, Article 114667
• Main Authors: Fan, Qingwen, Song, Chaoyun, Fu, Peng
• Format: Article
• Language: English
• Subjects: Biomass; Interface polarization; Microwave absorption; MnO2; Porous carbon
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.114667

In this study, we explored the effectiveness of enhancing microwave absorption capabilities of biomass-derived porous carbon by introducing MnO2 through thermochemical techniques. The results showed that the MnO2-C exhibited higher values in both the real and imaginary parts of the dielectric constant compared to the Control, indicating that the addition of MnO2 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 MnO2 optimized the dielectric losses and promoted the reconstruction of charge, enabling MnO2-C to demonstrate superior microwave absorption performance, particularly in the high-frequency range. This is attributed to the multiple polarization mechanisms present in MnO2-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 MnO2-C achieving a minimum reflection loss value of −46.2 dB and an expanded effective absorption bandwidth. Overall, the MnO2-C composite, with its optimized electromagnetic properties and complex microstructure, provides valuable insights for the development of new, highly efficient microwave absorption materials. [Display omitted] •MnO2-C achieves high microwave absorption performance with impedance regulation function.•It explains the promoting effect and absorption mechanism of composites on microwave absorption performance.•The minimum reflection loss (RL) of MnO2-C is −46.2 dB at the coating thickness of 6.0 mm.•The MnO2 reduces the thickness of the coating and increases the effective absorption bandwidth.