Engineering carbon fibers with dual coatings of FeCo and CuO towards enhanced microwave absorption properties

Decorating carbon fibers (CFs) with multiple coatings has attracted great interest in microwave absorption due to their better performance than the CFs with a sole coating. In this work, CFs with dual coatings of FeCo alloy and CuO (CF/FeCo/CuO) were synthesized by facile electrodeposition of FeCo alloy and copper followed by thermal oxidation in air. Morphology, crystalline structure, and magnetic and microwave properties of CF/FeCo/CuO composite fibers were studied as a function of oxidization temperature. The copper coating on CF/FeCo was converted to CuO after oxidization at 300, 350, and 400 °C for 4 h. It was found that the oxidization temperature did not change the crystalline structure of the CF/FeCo/CuO composite fibers. However, the temperature affected the morphology of CuO coating as well as the complex permittivity and permeability of the CF/FeCo/CuO composite fibers. Results showed that the CF/FeCo/CuO composite fibers showed significantly better absorption than the CFs with a sole FeCo coating. Furthermore, the CF/FeCo/CuO composite fibers oxidized at 400 °C (CF/FeCo/CuO-400) exhibited better absorption behavior than CF/FeCo/CuO-300 and CF/FeCo/CuO-350 likely due to the presence of CuO nanorods on the outermost surface. To our knowledge, this is the best microwave absorption performance for composite CFs reported in literature. This work provides an alternative approach for the control of the microwave absorption properties of CFs.