Fabrication of bimetallic metal–organic frameworks derived cobalt iron alloy@carbon–carbon nanotubes composites as ultrathin and high-efficiency microwave absorbers

Developing lightweight and high-efficiency microwave absorbents derived from metal-organic frameworks (MOFs) was proven to be a promising strategy to solve the increasingly serious problem of electromagnetic radiation pollution. In this work, nitrogen-doped cobalt iron alloy@carbon-carbon nanotubes (CoFe alloy@C-CNTs) composites were fabricated through an aging and pyrolysis two-step method. Results revealed that the attained composites presented a unique four-pointed star morphology and lots of CoFe alloy nanoparticles were uniformly embedded into the porous carbon matrix. Moreover, it was found that the pyrolysis temperature had a notable effect on the microwave absorption properties of CoFe alloy@C-CNTs composites. Remarkably, the obtained composite under 700.0 °C pyrolysis treatment showed the optimal minimum reflection loss of -54.5 dB with an ultrathin thickness of 1.4 mm and maximum effective absorption bandwidth of 5.0 GHz at a low thickness of 1.6 mm. Additionally, the possible electromagnetic attenuation loss mechanisms of attained composites were illuminated. It was believed that our results could be helpful for fabricating ultrathin and high-performance microwave absorbing materials derived from MOFs.