Hollow Spheres of Ti₃C₂T_x with a Nanometer-Thick Wall for High-Performance Microwave Absorption

Two-dimensional (2D) Ti3C2Tx MXene has attracted huge attention in the field of electromagnetic wave attenuation, but its poor impedance matching with air leads to weak microwave absorption (MA) capability. Herein, hollow spheres of Ti3C2Tx with a nanometer-thick wall were prepared through a sacrificial template strategy, and their MA performance was investigated for the first time. The unique macroporous structure constructed by Ti3C2Tx hollow spheres benefits excellent MA performance by improving impedance matching, multiple reflections and scattering, and polarization relaxation. With only 10 wt % filler loading in the paraffin, the minimum reflection loss (RLmin) of Ti3C2Tx hollow spheres can reach −49.2 dB at 10.3 GHz at a thickness of 2 mm, which is much superior to that of Ti3C2Tx nanosheets (−7.4 dB). Moreover, the MA performance of Ti3C2Tx hollow spheres can be adjusted in the range of 3.7–16.5 GHz by changing the cavity size and thickness. This study provides a facile and effective strategy for designing lightweight and high-performance MXene-based microwave absorbers.