Biomass-derived porous carbon materials have attracted considerable attention as promising electromagnetic (EM) wave absorbers due to their lightweight characteristic, ultra large surface area as well as high dielectric loss. However, the dielectric loss alone is difficult to achieve high EM wave absorption performance. In this work, core-shell Co@Co₃O₄/porous carbon composites are designed and synthesized by a facile hydrothermal and subsequent pyrolysis process through using fish scale as carbon precursor, Co(NO₃)₂·6H₂O as Co source, aiming to offer more loss mechanism and achieve high EM wave absorption performance. As expected, the as-prepared composite showed strong absorption (−89.3 dB at 2.4 mm) with broadened bandwidth (11.92–18 GHz at 2 mm). Such excellent absorption performance could be attributed to the reasonable design of composite. Special porous structure not only is beneficial to the impedance matching to allow EM wave to enter absorber as much as possible, but also could offer a conductive path for electronic, booming conductive loss. Besides, the designed unique core-shell structure provides Co-Co₃O₄ interfaces along with Co₃O₄-C, C-void interfaces are propitious to enhance interface polarization loss. Moreover, Co@Co₃O₄ nanoparticles could also supply the magnetic loss to composites to further absorb EM wave from another point. Although there are many previous works about Co@Co₃O₄ have been reported, little works have been done on the composites of biomass porous carbon with core-shell Co@Co₃O₄ with such excellent EM wave absorption performance. This work indicates that the as-obtained core-shell Co@Co₃O₄/C could be a candidate for dealing with the increasing EM wave pollution.

生物质衍生的多孔碳材料由于其轻量级的特性，超大的表面积以及高的介电损耗而备受瞩目，成为有前途的电磁波（EM）吸收剂。然而，仅介电损耗难以实现高EM波吸收性能。在这项工作中，以鱼鳞为碳前驱体Co（NO ₃）₂ ·6H ₂，通过水热和随后的热解过程，设计并合成了核壳型Co @ Co ₃ O ₄ /多孔碳复合材料。O作为Co源，旨在提供更多的损耗机制并实现高EM波吸收性能。如预期的那样，所制备的复合材料显示出较强的吸收能力（2.4 mm时为−89.3 dB），带宽更宽（2 mm时为11.92–18 GHz）。如此优异的吸收性能可归因于复合材料的合理设计。特殊的多孔结构不仅有利于阻抗匹配，以使EM波尽可能多地进入吸收体，而且还可以为电子爆炸性的导电损耗提供导电路径。此外，设计独特的核-壳结构提供了Co-Co ₃ O ₄界面以及Co ₃ O ₄ -C，C-void界面有利于增强界面极化损耗。而且，Co @ Co ₃O ₄纳米颗粒还可以向复合材料提供磁损耗，以进一步吸收来自另一点的EM波。尽管以前有许多关于Co @ Co ₃ O _4的报道，但是对具有如此优异的EM波吸收性能的生物质多孔碳与核壳Co @ Co ₃ O ₄的复合材料的研究很少。这项工作表明，获得的核壳型Co @ Co ₃ O ₄ / C可能是应对日益严重的EM波污染的候选者。