Fabrication of ultralight helical porous carbon fibers with CNTs-confined Ni nanoparticles for enhanced microwave absorption

It is extraordinarily difficult to develop low-cost and lightweight microwave absorbing materials that meet the needs of modern technology. Making rational use of biomass to prepare microwave absorbers is a sustainable way. Herein, we develop the catalytic self-deposition (CSD) technology and fabricate ultralight magnetic helical porous carbon fibers (MHPFs) with surface-grown carbon nanotubes (CNTs). There is no need to use expensive, flammable and explosive exogenous gases, avoiding the high energy consumption and potential safety issues faced by traditional energy-intensive catalytic chemical vapor deposition (CCVD) processes. The combined use of in-situ dipping and CSD technology realizes the in-situ growth and morphology control of CNTs encapsulated Ni nanocatalysts. Owing to the sophisticated structure, large specific surface area, complementary loss mechanisms and well-matched impedance, MHPFs exhibit exceptional microwave absorption performance. Notably, under the ultralow filler loading (5%), the strongest reflection loss (RL) exceeds −55.39 dB at 8.4 GHz, and the maximum absorption bandwidth (EAB, RL < −10 dB) reaches 4.7 GHz at the matching thickness of 2.00 mm. The study might shed light on the ultralow filler loadings and low-cost preparation of efficient microwave absorbers.