Cl-terminated decoration to modulate the permittivity of MXene for enhanced electromagnetic-absorbing performance

The explosive growth of communication technology has given rise to a large number of high-quality electromagnetic wave (EMW) absorbing materials, and single-component materials are often difficult to satisfy the demand. In this study, we propose an etching method of molten chlorine salts under vacuum to prepare Cl-terminated MXene (MX-Cl) which can meet the requirements of "thin, light, wide and strong" and realize the application of single-component absorbing materials. In the X and Ku bands, MX-Cl achieves a strong reflection loss of -42.99 dB and an effective absorption bandwidth of 3.44 GHz with the 1.2 mm matching thickness. The presence of Cl groups restricts the free electron movement of surface-Ti, which controls the conductivity of the MX-Cl and optimizes its permittivity. Dipole polarization induced by Ti-Cl, interfacial polarization between MXene layers and multiple scattering effects inside the layers all significantly increase the dielectric loss of the MX-Cl considerably. This study provides a new approach to investigating the effect of single atoms on the dielectric properties of materials. This work also offers a simple and low-cost process for the preparation of single-component MXene EMW-absorbing materials. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.