To clarify the role of Ti₂SnC surface oxides in the arc erosion resistance of Ag-based electrical contacts, a pre-oxidation strategy is employed to construct a controllable oxide layer at the Ag/Ti₂SnC interface. Results show that pre-oxidation induces surface decomposition of Ti₂SnC, leading to the in-situ formation of a TiO₂-dominated oxide layer, and promoting the diffusion of Sn into the Ag matrix. Although such interfacial reconstruction decreases the initial density, tensile strength, and electrical conductivity, it enhances local solid-solution strengthening and increases interfacial hardness. After 10,000 arc cycles, the pre-oxidized Ag/Ti₂SnC@TiO₂ composite exhibits lower mass loss, average arcing time, and arc energy. Combined with the post-erosion surface morphology, the results suggest that the preformed oxide interface regulates interfacial diffusion behavior, which further affects arc-root attachment and migration, thereby suppressing localized arc action and molten Ag splashing. This study reveals the role of Ti₂SnC surface oxides in regulating interfacial structure and arc erosion behavior, providing insights into the interfacial design of Ag/MAX-phase electrical contact materials.

Since 2019, research into MXene derivatives has seen a dramatic rise; further progress requires a rational design for specific functionality. Herein, through a molecular design by selecting suitable functional groups in the MXene coating, we have implemented the dual N doping of the derivatives, nitrogen-doped TiO₂@nitrogen-doped carbon nanosheets (N-TiO₂@NC), to strike a balance between the active anatase TiO₂ at low temperatures, and carbon activation at high temperatures. The NH₃ reduction environment generated at 400 °C as evidenced by the in situ pyrolysis SVUV-PIMS process is crucial for concurrent phase engineering. With both electrical conductivity and surface Na⁺ availability, the N-TiO₂@NC achieves higher interface capacitive-like sodium storage with long-term stability. More than 100 mAh g⁻¹ is achieved at 2 A g⁻¹ after 5000 cycles. The proposed design may be extended to other MXenes and solidify the growing family of MXene derivatives for energy storage.