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In this study, a composite material based on agricultural waste coconut shells was successfully developed as an efficient, lightweight, and sustainable electromagnetic wave (EMW) absorber. Specifically, coconut shells were used as the raw material, and a simple one-step activation charring process was employed to obtain coconut shell porous carbon (CSPC). ZnFe2O4 with a hollow spherical structure was then in situ grown on the surface of CSPC, resulting in a special ZnFe2O4/ CSPC composite material. Due to its unique hollow structure, porous characteristics, and heterogeneous interfaces, the composite material achieved optimized impedance matching, leading to excellent EMW absorption performance. The fabricated ZnFe2O4/ CSPC composite demonstrated a minimum reflection loss ( RLmin) of − 37.32 dB at 10.80 GHz and an effective absorption bandwidth of 2.40 GHz at a thickness of only 2.0 mm. SEM and TEM analyses confirmed that the composite possessed a hollow and porous structure, while the BET specific surface area was measured at 133.709 m2 g⁻1. Based on the synergistic effects of ZnFe2O4 and CSPC, dielectric losses, magnetic losses, and impedance matching, the potential EMW absorption mechanisms were proposed. The ZnFe2O4/ CSPC composite material prepared in this study was a novel, green, and sustainable EMW absorber.
Abstract
1 Introduction
2 Experimental
2.1 Materials
2.2 Preparation of CSPC
2.3 Preparation of hollow ZnFe2O4
2.4 Preparation of hollow ZnFe2O4CSPC composites
2.5 Characterization
3 Result and discussion
3.1 Formation of the ZnFe2O4CSPC composite
3.2 Morphological structure
3.3 Chemical composition analysis
3.4 Microwave absorption performance
3.5 Microwave absorption mechanism
4 Conclusion
Acknowledgements
References
