Hierarchical Ti3C2Tx MXene/Carbon Nanotubes Hollow Microsphere with Confined Magnetic Nanospheres for Broadband Microwave Absorption

Hierarchical hollow structure with unique interfacial properties holds great potential for microwave absorption (MA). Ti3C2Tx MXene has been a hot topic due to rich interface structure, abundant defects, and functional groups. However, its overhigh permittivity and poor aggregation‐resistance limit the further application. Herein, a hierarchical MXene‐based hollow microsphere is prepared via a facile spray drying strategy. Within the microsphere, few‐layered MXene nanosheets are separated by dispersed carbon nanotubes (CNTs), exposing abundant dielectric polarization interfaces. Besides, numerous magnetic Fe3O4 nanospheres are uniformly dispersed and confined within nano‐cavities between 1D network and 2D framework. Such a novel structure simultaneously promotes interfacial polarization by ternary MXene/CNTs/Fe3O4 interfaces, enhances magnetic loss by microscale and nanoscale coupling network, enlarges conduction loss by MXene/CNTs dual‐network, and optimizes impedance matching by hierarchical porous structure. Therefore, Fe3O4@Ti3C2Tx/CNTs composite achieves excellent MA property with a maximum reflection loss of −40.1 dB and an effective bandwidth of 5.8 GHz at the thickness of only 2 mm. This work demonstrates a feasible hierarchical structure design strategy for multi‐dimension MXene composite to realize the high‐efficiency MA performance.