Sulfur-Doped MXene-Based Nanocomposites for Efficient Electromagnetic Wave Absorbers via Polarization and Magnetization

Ti 3 C 2 T x (MXene) materials with multilayered structures have been widely investigated as promising absorption materials. However, the electromagnetic wave absorption performance of a single Ti 3 C 2 T x MXene has always been limited by interface mismatches due to high reflectivity. In this work, sulfur-doped MXene-based nanocomposites were constructed by a mild doping and calcination method and performance was regulated by manipulating chemical composition, loading ratio, electromagnetic parameters, or impedance matching. Here, sulfur-doped MXene and titanium dioxide produced via high-temperature calcination (S-MXene (TiO 2 )) provided abundant defects and functional groups, resulting in dipole polarization relaxation. The introduction of Ag improved the electrical conductivity, and the CoNi alloy could enhance the magnetic loss and improve impedance matching. The electromagnetic wave absorption ability was enhanced thanks to the combined effects of suitable conductivity, dipole polarization, interface polarization, and magnetic loss. The S-MXene (TiO 2 )/Ag/CoNi nanocomposites exhibited a high reflection loss of −63.1 dB at a thickness of 2.1 mm and a wide effective absorption bandwidth of 5.2 GHz at a thickness of 2.0 mm. Moreover, by adjusting the mass ratio of nanocomposites’ components, the minimum reflection loss value was up to −80.9 dB at only 1.5 mm. This mechanism of increasing material loss through doping is of great significance for improving the electromagnetic wave absorption of MXene-based nanocomposites.