Surface‐Functionalised <scp> Ti ₃ C ₂ T _x </scp> for Stable Dispersion and Tribofilm Reinforcement in <scp>PAO20</scp> Lubrication

ABSTRACT In view of the promising application potential of two‐dimensional MXenes (Ti 3 C 2 T x ) in lubrication, along with the challenge of their poor dispersibility in non‐polar base oil, this work reports the surface functionalisation of Ti 3 C 2 T x through the covalent grafting of alkylphosphonic acid (TDPA). TDPA grafting converts the surface properties of Ti 3 C 2 T x from polar to non‐polar, significantly enhancing its dispersion stability in non‐polar PAO20 base oil. Tribological performance tests showed that as an additive, TDPA‐Ti 3 C 2 T x improved the anti‐wear performance of PAO20 by 38.1%. Its excellent performance is mainly attributed to the high mechanical strength, easy interlayer shear characteristics of the modified nanosheets, and the synergistic effect of the protective tribochemical film formed in situ during the friction process. The TDPA functionalisation strategy is an effective way to realise the efficient application of Ti 3 C 2 T x in non‐polar lubricating systems, and provides a new idea for the design of high‐performance lubricating additives.