A hierarchical carbon Fiber@MXene@ZnO core-sheath synergistic microstructure for efficient microwave absorption and photothermal conversion

Continuous 3D hierarchical construction has been proved to serve as a feasible method to prepare high-efficiency microwave absorption (MA) composites. Herein, an innovative hierarchical carbon fiber (CF)@MXene@ZnO core-sheath synergistic structure with tunable and efficient MA performance has been synthesized via a self-assembly (MXene) and hydrothermal (ZnO) process. Because of increased conductivity loss of the interlayer MXene sheath due to synergistic effects and the enhanced impedance matching of the outer ZnO layer, the optimal reflection loss (RL) value of CMZ2 is −67.35 GHz at 9.0 GHz at a thickness of 3.5 mm and the optimal effective absorption bandwidth (EAB) is 5.44 GHz, covering the full X band at a thickness of 4.0 mm. Furthermore, the CMZ microrods can be used as energy transformers and molecular heaters due to the synergistic effects of the high photothermal conversion efficiency of MXene, high photocatalytic activity of ZnO, and high thermal conductivity of CF. When used as wearable CMZ/polyurethane (PU) composite coatings, the surface temperature increases rapidly with a healing efficiency of above 91% for mechanical damage. These results provide a new strategy to fabricate wearable materials with effective MA and photothermal properties for designing safe and wearable devices.