Co nanoparticles supported on cotton-based carbon fibers: A novel broadband microwave absorbent

Aiming at the disadvantages of high cost, complex processes, and low yield of carbon-based microwave absorbing materials. In this study, Co/C fibers were successfully prepared by using low-cost cotton as carbon source. The synthetic route was a flexible two-step approach consisting of immersion and subsequent carbothermal reduction in N2 atmosphere. By means of controlling the Co(NO3)2·6H2O concentration and calcination temperature, Co nanoparticles with different loading amount and particle size were uniformly dispersed along the cotton-based carbon fibers. The Co loading amount, calcination temperature, and filling rate on electromagnetic parameters and microwave absorption performance were systematically studied. Among the Co/C fibers obtained at different Co(NO3)2·6H2O concentration and calcination temperatures, the Co/C fibers synthesized at 600 °C with 0.5 M Co(NO3)2·6H2O exhibited the best microwave absorption performance. The reflection loss (RL) values less than −10 dB were obtained in the frequency range of 11.3–18 GHz, which covered the entire Ku-band (from 12 to 18 GHz). Such excellent microwave absorption performance was attributed to the synergistic effect of dielectric loss, magnetic loss, and good impedance matching. Owing to the characteristics of cost-effective synthetic strategy, low density, and good microwave absorption, the Co/C fibers are highly promising as economic and broadband microwave absorbent.