Intercalation-Induced Interlayer and Defect Engineering in Ti₃C₂T_<i>x</i> MXene for Ultralow-Reflection Electromagnetic Interference Shielding

Abstract

Interlayer and defect engineering significantly affects the electrical conductivity and electromagnetic interference (EMI) shielding of Ti₃C₂T_<i>x</i> MXene. Previous studies have prioritized the size of the intercalant over its synergy with chemical affinity, limiting the elucidation of the intercalation mechanism and the precise control of the interlayer spacing (<i>d-</i>spacing). Herein, we synthesize MXene aerogels with a tunable <i>d-</i>spacing and defect density using a series of amine molecules of different sizes and chemical affinities as intercalants and cross-linkers. Particularly, the intercalation of <i>p</i>-phenylenediamine (PPD) increases the <i>d-</i>spacing of MXene from 0.960 to 1.642 nm. Simultaneously, the increased <i>d-</i>spacing contributes to an increased defect density within the Ti-Ti layer. Hence, the PPD@MXene aerogel exhibits reduced surface electric field intensity and increased internal polarization loss, resulting in absorption-dominated EMI shielding. The absorptivity reaches 0.92, far exceeding the reported shielding materials, with a shielding effectiveness of 50.4 dB. This study provides a theoretical foundation and preliminary guidance for the development of interlayer-engineered MXene shielding materials.