Hierarchical Ti₃ C₂ T_x 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). Ti₃ C₂ T_x 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 Fe₃ O₄ 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/Fe₃ O₄ 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, Fe₃ O₄ @Ti₃ C₂ T_x /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.