Study on the electromagnetic wave absorption performance of Ti₃C₂ MXene with different etching states

In this paper, a safe, low-cost and simple operating LiF + HCl etching method combined with freeze-drying was used to prepare Ti₃C₂T_X MXene with different etching states. The results indicated that the morphology of Ti₃C₂T_X gradually changed from stacked to accordion structure and finally to ultra-thin dispersed sheets with increasing etching. We also investigated different surface functionalization and electromagnetic properties of synthesized samples. In 2–18 GHz, the effective absorption bandwidth (EAB) (RL < − 10 dB) of the sample with accordion microstructure reaches 3.92 GHz at thickness of 1.27 mm, while for the ultra-thin dispersed Ti₃C₂T_X sheets, the EAB is increased to 4.40 GHz at thickness of 1.26 mm. To our knowledge, this is the minimum thickness in Ti₃C₂-related reports. We attribute the improved wave absorption performance to the dielectric and magnetic loss induced by termination layer as well as the unique interface effects, which are also beneficial to optimize the impedance matching and achieve multi-mode attenuation even in high frequency band.