Controlled preparation of lightweight, resilient helical carbon fibers for high-performance microwave absorption and oil-water separation

Helical carbon nanomaterials are highly promising candidates for microwave absorption (MA) and oil-water separation due to their unique geometries and intrinsic carbon properties. This study presents a controlled synthesis of lightweight, resilient helical carbon nanofibers (HCNFs) using chemical vapor deposition. Three structures-straight carbon nanofibers (CNFs), twisted carbon nanofibers (TCNFs), and spring-like carbon nanofibers (SCNFs)-were fabricated, and their MA properties were systematically studied. SCNFs exhibited superior MA, achieving a minimum reflection loss (RLmin) of −50.4 dB at 10.3 GHz with a thickness of 2.5 mm, along with an effective absorption bandwidth of 4.1 GHz at a thickness of 1.74 mm. The improved performance of the material is ascribed to the helical structure and the presence of defects within the fibers, which facilitate enhanced dielectric and magnetic losses, as well as optimized impedance matching. Furthermore, the hydrophobic and oleophilic nature of these nanofibers facilitates efficient oil-water separation. These findings provide valuable insights for the design of multifunctional materials aimed at MA and environmental applications.