It is highly desirable yet challenging to develop high-performance microwave absorption materials with lightweight, thin thickness, and strong absorption capability over broad frequency ranges by simple and cost-effective methods. Herein, we design an ultralight (~54 mg cm⁻³) magnetic-carbon hybrid material to achieve superior microwave absorption performances. By instantaneous freezing-induced self-assembly of Fe³⁺, Co²⁺-glucose complexes on a cheap and water-removable template (i.e., NaCl), the as-made composite features 3D hierarchical porous structure and nanosheet-like carbon pore walls embedded with nanocrystalline CoFe₂O₄. The chemical composition can be controlled by simply altering the ratio of Co²⁺ (Fe³⁺) and glucose. Benefitting from the structural and compositional advantages, the optimized composite absorber exhibits a minimum reflection loss value of − 52.29 dB at a thin thickness of 2.0 mm and an effective absorption bandwidth reaching 5.36 GHz (12.64–18 GHz) at a low filler loading of 20 wt%. The microwave absorption mechanism survey reveals that the weak surface reflection and strong dissipation capacity induced by nanosheet-like pore walls combined with the multiple internal reflections caused by 3D hierarchical porous structure contribute to robust impedance matching and strong microwave attenuation ability. This work may offer new insights for designing highly effective magnetic-carbon microwave absorbers with low density and wide absorbing frequency.

通过简单且具有成本效益的方法开发具有重量轻、厚度薄且在宽频率范围内具有强吸收能力的高性能微波吸收材料是非常可取但具有挑战性的。在此，我们设计了一种超轻（~54 mg cm ^-3）磁碳混合材料，以实现卓越的微波吸收性能。通过瞬时冷冻诱导 Fe ³⁺、Co ²⁺ -葡萄糖复合物在廉价且可脱水的模板（即 NaCl）上自组装，制成的复合材料具有 3D 分层多孔结构和纳米片状碳孔壁嵌入纳米晶 CoFe ₂ O ₄。化学成分可以通过简单地改变Co的比例来控制²⁺ (Fe ³⁺ ) 和葡萄糖。受益于结构和成分优势，优化的复合吸波材料在 2.0 mm 的薄厚度下表现出 - 52.29 dB 的最小反射损耗值和在 20 的低填料负载下达到 5.36 GHz (12.64-18 GHz) 的有效吸收带宽重量％。微波吸收机制研究表明，纳米片状孔壁引起的弱表面反射和强耗散能力与 3D 分层多孔结构引起的多次内反射相结合，有助于实现稳健的阻抗匹配和强微波衰减能力。这项工作可能为设计具有低密度和宽吸收频率的高效磁碳微波吸收器提供新的见解。