Hierarchically porous N-doped dual-carbon coupled Co5.47N composite with tunable electromagnetic shielding and absorption properties

Electromagnetic interference (EMI) and pollution issues are becoming increasingly prominent. It is of great scientific significance and practical value to develop lightweight, efficient and tunable electromagnetic wave (EMW) attenuating materials. Herein, a three-dimensional (3D) hierarchical porous N-doped dual-carbon (glucose-derived carbon and reduced graphene oxide (rGO)) coupled Co_5.47N (Co_5.47N@HNCF) composite was reasonably designed and prepared via simple and low-cost methods, which exhibited excellent electromagnetic attenuation properties. By appropriately adjusting the filling amount of Co_5.47N@HNCF, tunable EMI shielding and EMW absorption properties could be achieved. At high filling amount (40 wt%), the highly conductive Co_5.47N@HNCF composite had excellent EMI shielding effectiveness (EMI SE) in X-band (8.2~12.4 GHz), with a maximum total electromagnetic shielding effectiveness (SE_T) of 81.6 dB (average EMI SE of 76.8 dB) and a thickness of 2 mm. Particularly, when the thickness is only 0.8 mm, the SE_T could reach 32 dB. While at low filling amount (15 wt%), Co_5.47N@HNCF composite with suitable impedance matching showed remarkable EMW absorption performance, exhibiting high values of reflection loss (RL) of -45.86 dB in 2~18 GHz. The high-performance EMW attenuation in Co_5.47N@HNCF could be ascribed to the construction of stable 3D conductive dual-carbon frameworks and Co_5.47N nanoparticles with abundant N vacancies. The dielectric and magnetic components of the system acted synergistically, possessing abundant heterogeneous interfaces and defects, which could induce various loss modes such as multiple reflections/scattering, conductive loss, magnetic loss and polarization loss to synergistically dissipate EMW. Therefore, this study endeavors to give an effective strategy for the preparation of low-cost, lightweight, and highly efficient tunable EMW attenuation materials.