1D\nElectromagnetic-Gradient Hierarchical Carbon Microtube\nvia Coaxial Electrospinning Design for Enhanced Microwave Absorption

Abstract

1D\nstructures have been gaining traction in the microwave absorption\n(MA) field benefiting from their electromagnetic (EM) anisotropy.\nHowever, there remain considerable challenges in adjusting EM properties\nby structural design. Herein, using the coaxial electrospinning and\nsolvothermal method, the EM gradient has been achieved in TiO₂@Co/C@Co/Ni multilayered microtubes. From the outer layer\nto the inner one, the impedance matching is gradually worsened, while\nthe EM loss capacity is continuously enhanced, facilitating both the\nincidence and attenuation of microwave. Besides, 1D structural anisotropy\nsimultaneously realizes multilevel magnetic interaction and 3D conductive\ndouble network. Therefore, the 1D EM-gradient hierarchical TiO₂@Co/C@Co/Ni carbon microtube composite exhibits excellent\nMA performance. Its maximum reflection loss (RL) value reaches −53.99\ndB at 2.0 mm and effective absorption bandwidth (EAB, RL ≤\n−10 dB) is as wide as 6.0 GHz, covering most of the Ku band\nwith only 15% filling. The unique design of 1D EM-gradient hierarchical\ncomposites promises great potential in the construction of advanced\nMA materials.