V-Based MXene/MAX Heterostructure Composites with Enhancing Dielectric Loss for Broadband Microwave Absorption.

Electromagnetic wave absorption performance is strictly dependent on attenuation and impedance matching, which are directly influenced by the ratio of MXene/MAX in the multilayer structured MXene/MAX composites. However, there is still a challenge to achieve collaborative optimization of dielectric loss and impedance matching by precisely regulating the proportional relationship of MXene/MAX. Herein, V-based MXene/MAX heterostructure composites with different V 2 C/V 2 AlC ratios were successfully synthesized by rationally controlling the temperature and time of the hydrothermal reaction. Experimental results indicated that V 2 C-100 °C-1 harvested the balance between reduced impedance matching and enhanced dielectric losses, which was attributed to the mildly enhanced conduction loss and polarization loss. The first principles indicated that abundant electrons migrate from the V atoms of the MXene to the C atoms of the MAX phase. The charge redistributed and accumulated at the interface, exciting the increase in the dielectric loss of V 2 C-100 °C-1. As a result, the V 2 C-100 °C-1 heterostructure composite had an excellent electromagnetic absorption effect with a minimum reflection loss of -50.06 dB and a wide effective absorption bandwidth of 4.0 GHz (12.72-16.72 GHz). This work provides a valuable experience for the development of efficient MXene-based microwave absorbing materials.