Interfacial Solvent Engineering Enables Hydrothermally Stable MXene Heterostructures for Printed Wearable Electronics

Water-induced degradation of MXene during hydrothermal synthesis severely limits the construction of MXene-based heterostructures for further applications. Herein, an interfacial solvent-engineering strategy was developed to stabilize MXene under harsh hydrothermal conditions. Solvents with a stronger affinity for reactive Ti sites than water can preferentially adsorb at these sites. This competitive adsorption limits direct water-Ti contact and thereby suppresses subsequent MXene oxidation. DFT calculations were used to screen candidate solvents and support the proposed competitive adsorption mechanism, while the experimental results broadly followed the predicted trend. Deoxygenation experiments further supported the dominant role of water in MXene degradation. Molecular dynamics simulations revealed that preferential interfacial enrichment of DMF persists at 453 K despite enhanced thermal motion. In a 50 vol % DMF/H2O system, the MXene framework remained well preserved even under prolonged or higher-temperature hydrothermal treatment. This regulated solvent environment enabled the in situ growth of 1T-MoS2 on the preserved MXene framework. The conductive MXene framework and abundant active sites of 1T-MoS2 led to enhanced electrochemical performance. The resulting composite was further processed into printed microsupercapacitors and pressure sensors, which were integrated into a self-powered pressure-sensing system. This work establishes interfacial solvent engineering as an effective route to hydrothermally stable MXene heterostructures for printed wearable electronics.