Stabilization and Transformation of MXenes into Flexible and Thermal Oxidation-Resistant Non-van der Waals solids via Vapor-Phase Chemical Intercalation.

Non-van der Waals (non-vdW) solids derived from MXenes exhibit attractive physical and chemical properties but are usually limited by the irreversible phase transformation of MXenes into rocksalt structures at high temperatures. Herein, we develop a vapor-phase chemical intercalation strategy mediated by high-vapor-pressure zinc (Zn) to efficiently stabilize the transition metals (Ti, Nb, and V) with unsaturated d-orbitals in MXenes. This stabilization facilitates subsequent interlayer bonding via reaction with various metal vapors (Al, Ga, and In) at elevated temperatures, yielding a family of well-defined non-vdW solids with ultrathin layered structures. Moreover, this strategy is readily scalable, enabling the fabrication of a continuous non-vdW Al-Ti3C2 film featuring a heterogeneous architecture with a reconstructed MAX-like bonded region and a locally unbonded MXene region. These structural features endow the non-vdW Al-Ti3C2 film with exceptional mechanical flexibility, high-temperature oxidation resistance at 800 °C in air, and an electrical conductivity of ∼10 000 S cm-1. Consequently, the film demonstrates an electromagnetic interference shielding effectiveness of up to 47.9 dB at a thickness of 5 μm, along with durable infrared stealth performance under prolonged exposure at 500 °C for 48 h.