Transforming in-situ grown chitosan/ZIF-67 aerogels into 3D N-doped Co/CoO/carbon composites for improved electromagnetic wave absorption

Nowadays there is much room for improvement in the designed synthesis of high-performance electromagnetic wave absorbers by combining metal-organic frameworks (MOFs) and biomass components. Herein, 3D N-doped porous carbon cobalt/cobalt oxide (NPC/Co/CoO) composites were successfully prepared by transforming in-situ grown ZIF-67 clusters on a chitosan matrix. Analysis results showed that the N-doped carbonaceous composites obtained had unique porosity, high specific surface area, and defect-enriched structure, which provided numerous paths for electron transfer, leading to big benefits to interfacial polarization and dipole polarization. Most importantly, the ferromagnetic resonance and magnetic coupling were enhanced by ZIF-67-derived Co/CoO nanoparticles. By adjusting the content of metallic cobalt salt, pyrolysis temperature, and sample filling content, the optimal impedance matching properties of the composites could be optimized. When the matching thickness is 2 mm, the RLmin of NPC/Co/CoO-10/700–30 wt% achieved − 48.97 dB at 13.52 GHz, and the effective absorption bandwidth exceeds 5.36 GHz. The composites with excellent performance prepared by a controllable process using chitosan and ZIF-67 might be a promising alternative for the large-scale preparation of high-frequency electromagnetic wave absorbers.