Enhanced Oxidation-Resistant and Conductivity in MXene Films with Seamless Heterostructure.

MXene-based films have garnered significant attention for their remarkable electrical and mechanical properties. Nevertheless, the practical application of MXene is impeded by its intrinsic instability caused by spontaneous oxidation. The traditional anti-oxidative strategies frequently lead to a compromise in stability, electrical conductivity, and mechanical properties. In this study, a novel approach is proposed involving metal nano-armoring, wherein a copper layer with nano thickness is deposited onto MXene film surfaces to establish a uniform and seamless heterogeneous interface (MXene@Cu). The precise tunability and uniformity of this heterostructure are consistently demonstrated through both theoretical calculations and experimental results. The MXene@Cu films exhibit exceptional electrical conductivity of 1.17 × 106 S m-1, electromagnetic interference shielding effectiveness of 77.1 dB, and tensile strength of 43.4 MPa. More importantly, this heterostructure significantly improves MXene's stability against oxidation. After exposure to air for 30 days, the resultant MXene@Cu films exhibit a remarkable conductivity retention of 72.0%, significantly exceeding that of pristine MXene films (44.3%). This scalable synthesis approach holds significant promise for electronic device applications, particularly in electromagnetic shielding and thermal management.

Bridging sheet size controls densification of MXene films for robust electromagnetic interference shielding.

Numerous voids among the incompact layer-structure of MXene films result in their low ambient stability and poor innate conductivity for electromagnetic interference (EMI) shielding. Herein, we report a bridging-sheet-size-controlled densification process of MXene films by applying graphene oxide (GO) as a bridging agent. Specifically, the sheet size of GO is tailored to quantify a negative correlation of sheet size with densification for directing the preparation of most compact MXene-GO films. Benefiting from the shortest electron-transport-distance in the most compact structure, the conductivity of the MXene-GO film achieves 1.7 times (∼1.6 × 105 S/m) that of MXene film. The EMI shielding performance (5.2 × 106 dB/m) reaches the record-value among reported MXene films at 10 µm-scale thickness. Moreover, the compact structure boosts the ambient stability of MXene-GO films where the conductivity and EMI shielding performance remain 88.7% and 90.0% after 15 days, respectively. The findings rationale the structure-activity relationship of compact MXene films for flexible electronics.