Gallic Acid-Hybridized Antioxidant MXene Ink for Printable Electronic Devices

Printable two-dimensional (2D) transition metal carbide (MXene) inks have attracted significant attention due to their high intrinsic conductivity, excellent dispersibility in various solvents, and exceptional functional properties, such as high specific capacitance and sensing capabilities. However, susceptibility to oxidation of the existing MXene inks remains one of the key challenges, which severely compromises the long-term stability of printed devices, thereby limiting their broader applications. Herein, we propose an effective and facile strategy to formulate printable oxidation-resistant MXene inks through molecular-level interfacial coordination between MXene and gallic acid. The optimal MXene@gallic acid ink possesses high electrical conductivity (4239 S cm^–1), high oxidation inhibition efficiency (>10 times enhancement), remarkable environmental stability, and tunable rheological properties, which can be printed to create various electronic structures toward diverse applications. Encouragingly, the resulting dielectric-driven Joule heater not only exhibits faster temperature response at relatively low voltage but also shows enhanced cyclic stability as compared to pure MXene. Additionally, the printed wearable temperature sensor displays high sensitivity for temperature sensing, further demonstrating its applicability for printable flexible devices. Our methodology not only provides an effective strategy to address oxidation-degradation issues that exist in MXene-based electronics but also paves the path for the development of other oxidation-vulnerable nanomaterials toward printed electronics.