Ultralight Ti3C2Tx-derivative chrysanthemum-like Na2Ti3O7/Ti3C2Tx MXene quantum dots 3D/0D heterostructure with advanced microwave absorption performance

As an outstanding representative of two-dimensional materials, newly emerged Ti3C2Tx MXene has aroused widespread attention in the field of microwave absorption (MA). However, the high conductivity of Ti3C2Tx MXene is prone to lead to impedance mismatch, and the attenuation performance of incident electromagnetic waves in the Ti3C2Tx matrix needs to be further improved. To address these issues, Ti3C2Tx MXene quantum dots (MQDs) were applied in the field of MA for the first time, and combined with Ti3C2Tx derivative chrysanthemumlike Na2Ti3O7 to prepare Na2Ti3O7/MQDs composites with 3D/0D heterostructure. Compared with Ti3C2Tx MXene bulks and nanosheets, Ti3C2Tx MQDs possess larger specific surface area and richer surface-active groups and defects, which are more favorable for interfacial polarization and dipole polarization, while the moderate conductivity of Ti3C2Tx MQDs is conducive to impedance matching. The unique chrysanthemum-like Na2Ti3O7/ MQDs with 3D/0D heterostructure generates abundant heterointerfaces to promote the increase of interfacial polarization, achieves a rational combination of different conductive materials to optimize impedance matching, and facilitates multiple reflections of electromagnetic waves among numerous nanowires in the chrysanthemumlike structure. Benefiting from the good impedance matching and the synergistic effect of multiple loss mechanisms, Na2Ti3O7/MQDs composites show excellent MA performance with a minimum reflection loss of -48.28 dB at a thickness of 2.6 mm. Simultaneously, the effective absorption bandwidth comes up to 6.38 GHz at 2.5 mm thickness. This study demonstrates the potential of MQDs as efficient microwave absorbers and points out the direction for a wide application of various MQDs in the field of MA.