Fabrication of S-doped Ti₃C₂T_x materials with enhanced electromagnetic wave absorbing properties

Ti₃C₂T_x (MXene) materials with multilayered structures have been widely developed in various academic fields. However, the application of electromagnetic wave (EMW) absorption is limited because of the high conductivity, which leads to impedance mismatch. Herein, the impedance-matching properties were optimized by loading highly defective TiO₂ onto an MXene sheet with S-doping and high-temperature annealing treatment. This treatment enhanced the EMW absorption because of the synergistic effect between the appropriate conductivity and enhanced polarization. The results show that S-doped MXene-300 has a conductivity of 2.70 × 10^–5 S/cm and exhibits the best area of impedance matching among the investigated samples. When the as-prepared S-doped MXene-300 quality ratio with paraffin was 1:1, the minimum reflection loss could reach −44.91 dB with a 4 mm coating thickness. In addition, the widest effective absorption (reflection loss ≤–10 dB) frequency bandwidth was 5.88 GHz when the thickness was 2.5 mm, which indicated that the dipolar polarization is the main positive EMW attenuation pathway for the S-doped MXene absorber. This research provides a new means of developing high-performance MXene EMW absorbers with adjustable conductivity and dielectric loss.