Ni-Gd competitive growth in helical carbon nanofibers for tunable electromagnetic wave absorption

The widespread use of electronic information technology has increased electromagnetic radiation pollution, information leakage, and radar detection threats. This underscores the need for high-performance microwave absorbing materials to ensure information security, human health, and defense equipment survivability. While helical carbon nanofibers and traditional carbon-based composites have shown progress in microwave absorption, they still face challenges like poor impedance matching and inadequate doping control. To address these issues, this paper presents a strategy that uses helical carbon nanofibers as the conductive skeleton matrix, co-doped with gadolinium (Gd) and nickel (Ni). By controlling the doping concentrations, specific phases are induced, achieving fine regulation of microwave absorption performance. Ni/Gd@HCNFs-1.0 exhibits high absorption intensities at both thin (1.71 mm, -44.92 dB) and medium (3.30 mm, -54.17 dB) thicknesses, with an EAB of 4.96 GHz at 1.56 mm, indicating excellent thickness-frequency adaptability. Ni/Gd@HCNFs-0.5 delivers a strong minimum reflection loss (RL_min) of -62.97 dB at 3.25 mm. This work demonstrates that the Ni/Gd competitive growth synergistically optimizes electromagnetic parameters and impedance matching characteristics of HCNF-based composites, achieving superior microwave absorption with remarkable thickness adaptability. The proposed doping strategy establishes a versatile platform for the rational design of high-performance microwave absorbers with high performance.