Intercalation-Induced Interlayer and Defect Engineering in Ti3C2Tx MXene for Ultralow-Reflection Electromagnetic Interference Shielding

Interlayer and defect engineering significantly affects the electrical conductivity and electromagnetic interference (EMI) shielding of Ti3C2Tx 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 (d-spacing). Herein, we synthesize MXene aerogels with a tunable d-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 p-phenylenediamine (PPD) increases the d-spacing of MXene from 0.960 to 1.642 nm. Simultaneously, the increased d-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.