Structural design and element doping are the research hotspots in the preparation of lightweight absorbers with high absorption performance and low filling rate. This study employs different temperature carbonization and etching techniques to prepare the structure of hollow nitrogen-doped carbon flowers (HNC) and evaluate their microwave absorption performance. At an ultra-low filler loading of 5 wt.%, the microwave absorption intensity of HNC-800 remains stable at -50 dB with a thickness of 3.2 mm. It is noteworthy that the HNC-800 achieved the broadest effective absorption frequency band at a matching thickness of 2 mm, with a bandwidth of 5.36 GHz (ranging from 12.4 to 17.76 GHz). Such remarkable broadband and reflection loss performance can be attributed to the synergistic effects of the hollow porous network structure, interface polarization, and dipole relaxation mechanisms. More significantly, the reduction of the radar cross-section (RCS) amounts to as much as 31.67 dB m2, and it has been attested to possess excellent adsorption efficacy in practical application scenarios. HNC-800, as an absorbing material, holds potential for broad application prospects.

Lightweight flower-like nitrogen-doped carbon materials achieve efficient electromagnetic wave absorption
    Abstract
    1 Introduction
    2 Results and discussion
    3 Conclusion
    Acknowledgements 
    References

• Xianfei Xie(State Key Laboratory of Advanced Processing and Recycling of Non‑Ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China)
• Sheng Wang(State Key Laboratory of Advanced Processing and Recycling of Non‑Ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China)
• Danqiang Huang(State Key Laboratory of Advanced Processing and Recycling of Non‑Ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China)
• Jianfeng Dai(State Key Laboratory of Advanced Processing and Recycling of Non‑Ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China, School of Science, Lanzhou University of Technology, Lanzhou 730050, Gansu, China) Corresponding author
• Qing Wang(School of Science, Lanzhou University of Technology, Lanzhou 730050, Gansu, China)