Facile preparation and excellent microwave absorption properties of cobalt-iron/porous carbon composite materials

In this work, a cobalt-iron/biomass porous carbon (CoFe/BPC) composite material is prepared through a facile in situ reduction process using fir wood as the raw material. CoFe₂O₄ is successfully reduced to CoFe alloy by the BPC after the heat treatment process. The morphology characteristics indicate that the CoFe particles are uniformly distributed in the porous carbon matrix. Besides, compared to BPC and CoFe₂O₄/BPC samples, the CoFe/BPC composite material has higher dielectric and magnetic losses due to its carbon graphitization, porous structure, strong magnetism, and multicomponent effect. Electromagnetic (EM) wave absorption properties are determined in the frequency range of 8.2–12.4 GHz. The CoFe/BPC composite material has a minimum reflection loss of −53.6 dB at 10.9 GHz with a thickness of 2.2 mm. The results indicate that the CoFe/BPC composite material is expected to be a superior EM wave absorber. These encouraging findings provide insights into the preparation of promising practical applications of biomass-derived microwave absorbers.