Insight into lightweight MXene/Polyimide aerogel with high-efficient microwave absorption

Two-dimensional transition metal carbides and nitrides (MXenes) which enriched with surface functional groups, defects, and considerable interlayer spaces, demonstrate promising prospects in microwave absorption due to that significantly contribute to dielectric loss. However, their limited gelation ability in aqueous solutions and propensity for self-stacking restrict their applications. Addressing this, a lightweight Ti₃C₂T_x MXene/Polyimide (MP) aerogel nanocomposites without magnetic materials has been developed through a straightforward freeze-drying method, where ‘PI chains’ anchor the MXene layers, inhibiting self-stacking and enhancing interactions between the Ti₃C₂T_x nanosheets. The prepared composite aerogels with different MXene contents exhibit exceptional microwave absorption performance. When the thickness of the MP30% is 1.92 mm, the minimum reflection loss (RL_min) is −49.36 dB at 16.28 GHz, and the effective absorption bandwidth (EAB) reaches 6.9 GHz with a matching thickness of 2.5 mm. At 3.8 mm, MP45% achieves an RL_min of −80.4 dB. Additionally, MP aerogels have a notable role in fire protection and insulation. The microwave absorbing mechanism of lightweight MP aerogels from the perspectives of chemical composition and physical structure was deeply explored, which is helpful to the preparation of MXene/PI based aerogels with better microwave absorbing ability in the future. Furthermore, the radar cross section (RCS) reduction value of the optimized MP30% aerogel is simulated as high as 34.775 dBm² when the scattering angle is 90^o using the computer simulation technology (CST). The prepared MP aerogel with extraordinary radar attenuation ability could potentially be applied as efficient absorber candidates in practical applications.