Intercomponent stabilizing strategy for oxidation-resistant Ti3C2Tx composites with electrodeposited mesoporous polypyrrole armor

Abstract

Long-term stability of MXenes is essential for their practical applications, which can be potentially realized by coating strategies. Herein, the nanosheets-assembled Ti₃C₂T_x film was armored with p-toluenesulfonic acid-doped polypyrrole (PPy) coating via one-step electrodeposition. The deposition procedure was optimized by evaluating morphology, thickness, wettability, specific surface area, and porosity. Beyond providing protective shield for the surface and edges, PPy coating penetrated interlayer gaps of Ti₃C₂T_x, substituting confined water and expanding interlamellar space. Hence, the resulting Ti₃C₂T_x@PPy₂₀ composite exhibited robust oxidation-resistance, as confirmed by stable electrical conductivity after prolonged exposure to humid environments. Furthermore, PPy served as the conductive binder, effectively adhering Ti₃C₂T_x nanosheets together, thereby endowing mechanical tolerance while preserving its capacitance (357.1 F g⁻¹ at 10 mV s⁻¹). Density functional theory calculations revealed the formation Ti–N bonds between neutral-state N in PPy and Ti vacancies, facilitating electron transfer from Ti₃C₂ toward PPy. This interaction allowed Ti₃C₂T_x to behave as immobile counterions, ensuring the long-lasting electroactivity of PPy coating. Due to the mutually stabilizing effect, Ti₃C₂T_x@PPy₂₀ demonstrated excellent durability after 38 days of exposure to 97 % relative-humidity, while maintaining favorable rate performance. These findings provide a promising pathway for durable application of MXene-based materials.