In situ growing CNTs/TiO₂ heterojunction on MXene sheets for enhanced microwave absorption via multiple electron transfer paths and polarization

The novel two-dimensional Ti3C2Tx material exhibits great potential for microwave absorption owing to its 2D layered graphene-like structure and unique physical properties. However, the limited release of absorbing properties due to the low dielectric loss of Ti3C2Tx and its single loss mechanism pose challenges in meeting the functional requirements for microwave absorbers. Herein, carbon nanotubes (CNTs) were grown on the Ti3C2Tx substrates in a tip growth mode under the catalytic influence of Ni using the in situ induced method. Consequently, Ti3C2Tx/CNTs/TiO2 (TCT) structures were successfully prepared through carbonization conditions. It is worth noting that the composite material TCT-800 exhibits excellent absorption performance. The minimum reflection loss (RLmin) value reaches -44.6 dB when the matching thickness is only 1.4 mm, and the corresponding effective absorption bandwidth (EAB, RL < -10 dB) spans from 11.9 GHz to 15.9 GHz, totaling a range of 4.2 GHz. The excellent electromagnetic wave absorption performance of TCT-800 composites is attributed to the polarization phenomenon of more heterogeneous interfaces constructed by Ti3C2Tx nanosheets, CNTs, and TiO2 nanoparticles. This work provides a strategy for synthesizing Ti3C2Tx-based composites with strong electromagnetic attenuation and wide absorption bandwidth performance.