In-Situ formed Titanium-MXene nanomembrane as ultrathin van-der-Waals lubricant

High-performance solid lubricants are pivotal in curbing frictional energy consumption and wear-related emissions under high-temperature and high-load conditions. However, under nanoscale tribological contacts, layered two-dimensional materials may lose their incommensurate van der Waals (vdW) interfacial alignment in extreme environments, leading to frictional degradation. Here, we report the scalable fabrication of large-area, cost-effective Ti-MXene hybrid nanomembranes (<50  nm thick), composed of in-situ chemically bonded metallic Ti and Ti₃C₂T_x MXene nanocrystals. Our nanomembranes exhibit outstanding isotropic tribological properties within a temperature range spanning from room-temperature to 573 K under high contact pressures. They demonstrate near-zero wear with a wear rate below 10^-9 mm³/Nm, and an ultra-low coefficient of friction below 0.01, achieving mesoscale superlubricity even at contact pressures exceeding 10 GPa and elevated temperatures (473–573  K) under atomic force microscopy indentation. These remarkable properties stem from the unique nanostructure, exceptional strength and high ductility of our nanomembranes, along with an in-situ nano-oxidation and carbon migration initiated by MXene decomposition during wear. In-situ experiments and multiscale simulations reveal that the confinement of MXene within the Ti nanocrystals not only imparts self-lubricating behavior but also enhances wear resistance by lowering the energy barrier of the tribochemical protection. Furthermore, these nanomembranes function as ultrathin vdW-enabled solid lubricants, effectively reducing friction and wear on various technologically important engineering materials, such as titanium alloy, stainless steel, and polytetrafluoroethylene (PTFE).