Magnetized MXene Microspheres with Multiscale Magnetic Coupling and Enhanced Polarized Interfaces for Distinct Microwave Absorption via a Spray-Drying Method.

As a typical 2D (two dimensional) material, Ti3C2Tx, has been used as a promising microwave absorber (MA) because of its massive interface architecture, abundant natural defects, and chemical surface functional groups. However, its single dielectric-type loss and excessive high conductivity seriously restrict the further enhancement of MA performance. Herein, we first describe a simple spray-drying routine to reshape the 2D MXene into a confined and magnetized microsphere with tightly embedded Fe3O4 nanospheres (designated as M/F), contributing to the enhanced specific interfaces and strong dielectric polarization. These Fe3O4 magnetic units are highly dispersed into the dielectric Mxene framework, leading to the optimized impedance balance and electromagnetic coordination capability. This composite way effectively exceeds the conventionally physical mixing, simple loading, and local phase separation method. Meanwhile, strong magnetic loss capability with significantly improved magnetic flux line density is achieved from microscale MXene and nanoscale Fe3O4, confirming our 3D multiscale magnetic coupling network. Accordingly, the M/F composites hold distinct microwave absorption property with the strong reflection loss (-50.6 dB) and effective absorption bandwidth (4.67 GHz) at the thickness as thin as only 2 mm. Our encouraging strategy provides important designable implications for MXene-based functional materials and high-performance absorbers.