Multi‐Scale Design of Ultra‐Broadband Microwave Metamaterial Absorber Based on Hollow Carbon/MXene/Mo2C Microtube

Developing various nanocomposite microwave absorbers is a crucial means to address the issue of electromagnetic pollution, but remains a challenge in satisfying broadband absorption at low thickness with dielectric loss materials. Herein, an ultra‐broadband microwave metamaterial absorber (MMA) based on hollow carbon/MXene/Mo2C (HCMM) is fabricated by a multi‐scale design strategy. The microscopic 1D hierarchical microtube structure of HCMM contributes to break through the limit of thickness, exhibiting a strong reflection loss of ‐66.30 dB (99.99997 wave absorption) at the thinnest matching thickness of 1.0 mm. Meanwhile, the strongest reflection loss of ‐87.28 dB is reached at 1.4 mm, superior to most MXene‐based and Mo2C‐based microwave absorbers. Then, the macroscopic 3D structural metasurface based on the HCMM is simulated, optimized, and finally manufactured. The as‐prepared flexible HCMM‐based MMA realizes an ultra‐broadband effective absorption in the range of 3.7‐40.0 GHz at a thickness of 5.0 mm, revealing its potential for practical application in the electromagnetic compatibility field. An ultra‐broadband microwave metamaterial absorber (MMA) based on hollow carbon/MXene/Mo2C (HCMM) is fabricated by a multi‐scale design strategy. The HCMM exhibits highly‐efficient absorption under ultra‐thin matching thicknesses with the strongest reflection loss of ‐87.28 dB and the thinnest matching thickness of 1.0 mm. Meanwhile, the HCMM‐based MMA realizes broadband effective absorption covering 4–18 GHz.