The preparation and modulation of 1D porous nanofibers loaded with Co@NC for efficient microwave absorption through electrospinning

Abstract

1D nanofibers have been extensively applied in field of microwave absorption (MA) by virtue of large specific surface area, low percolation thresholds, and high aspect ratios. Through the modification of its physical properties and components, enhancement of MA capability is expected to be achieved. Herein, we modified the nanofibers by porous structure construction and dielectric/magnetic coupling, and further altered the chemical composition and microstructure of the absorbers through adjustment of annealing temperature and porogen addition, thus leading to effective modulation of electromagnetic properties. Specifically, we first prepared a polyacrylonitrile-based nanofiber by electrospinning. Subsequently, in situ growth of ZIF-67 and the construction of pore structure of the nanofibers were achieved simultaneously in aqueous solution. Ultimately, 1D (ZIF-67 derivatives)@(porous carbon nanofiber) were acquired by thermal field modulation. It suggests that, with the increase of annealing temperature, graphitization degree rises, enhancing conductive loss. Meanwhile, more divalent cobalt is reduced, leading to a rise in polarization loss and the effective modulation of magnetic properties. Besides, the rise in porogen addition is accompanied by a decrease in pore volume and an increase in pore size, enhancing electrical conductivity while increasing the number of defects, thus enhancing dielectric loss. Notably, when annealing temperature is 700 °C and porogen addition is 29 wt%, obtained material exhibits excellent reflection loss (−52.49 dB at 1.53 mm) and broad bandwidth (5.29 GHz at 1.62 mm). This approach offers a novel perspective for the preparation and modulation of electromagnetic properties of 1D nanofibers.