Biomass-based Co/C@Carbon composites derived from MOF-modified cotton fibers for enhanced electromagnetic attenuation

Recently, highly efficient electromagnetic attenuation materials are crucial for the development of modern electronics and telecommunications. Meanwhile, biomass-derived carbon materials have attracted widespread attention due to their availability and renewable characteristics. In this study, a composite with Co/C particles embedded in carbon networks was synthesized by pyrolysis of cotton fiber coated with ZIF-67, which are showing tunable and higher electromagnetic interference (EMI) shielding effectiveness (SE) than pure carbon networks. The remarkable performance originated from the aligned carbon networks and the Co/C particles connected by the carbon networks. The former can achieve the regulation of EMI SE by changing the angle between the fiber orientation direction and the direction of the incident EM-wave electric field, while the latter can play a role in catalytic graphitization and enhance the shielding performance. When decreasing the pyrolysis temperature and filling the composite powder with 30 wt% in the paraffin matrix, the minimum reflection loss (RLmin) can reach-58.8 dB at 5.12 mm. In addition, the effective absorption band (EAB) of the composite can cover the C-Ku band by adjusting the thickness from 3 to 7 mm. This work provides a potential guideline for efficient biomass-based electromagnetic attenuation materials.