Preparation of CTCNFs/Co₉S₈ hybrid nanofibers with enhanced microwave absorption performance

A three-step synthesis strategy has been applied to the preparation of Co₉S₈-loaded tubular carbon nanofibers (CTCNFs/Co₉S₈ hybrid nanofibers) with excellent microwave absorbing ability. Firstly, tubular polymer nanofibers (TPNFs) are synthesized using the confined self-condensation method that we developed. Afterwards, TPNFs are converted into surface carboxylated tubular carbon nanofibers (CTCNFs) by carbonization and subsequent acidification processes. Finally, a hydrothermal method is used for the controllable growth of Co₉S₈ nanoparticles on CTCNFs, and a series of CTCNFs/Co₉S₈ hybrid nanofibers with different Co₉S₈ loading are obtained. The prepared CTCNFs/Co₉S₈ hybrid nanofibers possess abundant effective interface and defect dipoles, which will lead to stronger polarization. Using the strategy of enhancing dielectric loss, the microwave dissipation ability of CTCNFs/Co₉S₈ hybrid nanofibers has been significantly improved, showing an excellent low-frequency absorbing performance with a minimum reflection loss of -46.81 dB@5.3 GHz. In addition, the composition, structure and properties of nanofibers have been systematically characterized. The Co₉S₈ loading on CTCNFs and the filler content of CTCNFs/Co₉S₈ hybrid nanofibers in matrix are studied and optimized. The microwave attenuation mechanism is also explained.