A controllable heterogeneous structure and electromagnetic wave absorption properties of Ti₂CT_{: X} MXene

Herein, Ti₂CT_x MXene and its derivatives with various heterogeneous structures were constructed via etching and a facile oxidation treatment. The effect of different oxidation conditions on their structural evolution and phase composition was studied in detail. Compared with that of pristine Ti₂CT_x MXene, the improvement in the electromagnetic wave absorption capability of the as-prepared Ti₂CT_x/TiO₂ and C/TiO₂ nanocomposites was attributed to their enhanced polarization loss and stronger conductivity loss. The enhanced polarization loss is caused by the generated heterogeneous interfaces and higher specific surface area, and the stronger conductivity loss is due to the completely exfoliated carbon layers. Additionally, the remaining multilayered structure after exfoliation of the carbon layers favors energy dissipation. The C/TiO₂ nanocomposites attain a minimum reflection coefficient of -50.3 dB at 7.1 and 14.2 GHz, and an effective absorption bandwidth of 4.7 GHz (covering the whole X-band) with a matching thickness of 2.1 mm; this indicates their excellent electromagnetic wave absorption properties. We believe that these nanocomposites with a heterogeneous structure also hold great promise for application in the fields of photocatalysis, lithium batteries, water purification, etc.