Controlled fabrication and microwave absorption performance of cucurbit-like carbon nanofibers

In this paper, cucurbit-like polymer nanofibers precursor is prepared by a simple and effective method. The extracted and unextracted precursors obtained via hypercrosslinking polymerization are vacuum carbonized at different temperatures to obtain magnetic and non-magnetic tubular carbon nanofibers. The microwave absorption properties of the nanofibers are compared. The effects of filler content, structure, and carbonization temperature on microwave absorption performance are explored. The microwave absorption mechanism is analyzed in depth. It is found that the carbonization temperature has a significant effect on the specific surface area, pore volume, graphitization degree, and magnetism of the nanofibers. The cucurbit-like magnetic nanofibers (CCMFs) carbonized at 750 °C have the best microwave absorption performance with a low filler content of 8 %. The minimum reflection loss (RL_min) is −45 dB@1.8 mm, and the effective absorption bandwidth (EAB) reaches 5.4 GHz. The cucurbit-like nanofibers (CCNFs) carbonized at 700 °C show better microwave absorption properties, the RL_min and EAB are −53 dB@2.4 mm and 7 GHz@2.5 mm, respectively. The prepared carbon nanofibers are light in weight, low in filler content, and have a special cucurbit-shaped microstructure. These advantages enable the nanofibers to exhibit excellent microwave absorption capacity and can be widely used as high-efficiency microwave absorbers.