Choline amino acid ionic liquid micelles enhance the oxidation resistance and tribological properties of MXene

The unique physicochemical properties and 2D layered structure of MXene make it a promising lubricant additive. However, its chemical instability limits its application in environmentally friendly and sustainable lubrication systems. Although various strategies have been explored to enhance the chemical stability and tribological properties of MXene aqueous solutions, these approaches often compromise MXene's chemical compatibility and require high-viscosity petroleum-based lubricants. In this study, choline hydroxide and amino acids were added to a Ti 3 C 2 T x aqueous solution, leading to the self-assembly of choline hydroxide and amino acids into ionic liquid micelles. These micelles effectively passivated the surface of Ti 3 C 2 T x and improved its chemical stability. The experimental and simulation results showed that the ionic liquid micelles facilitated the formation of hydrogen bonds and coordination bonds between the amino acid and the Ti 3 C 2 T x surface. This interaction increased the binding energy by 2.5 times, preventing oxidation and degradation for over 90 days of storage. Moreover, during frictional processes, a TiN/TiO 2 reaction film formed between choline hydroxide, amino acids, and Ti 3 C 2 T x contributed to improved tribological properties, reducing the friction coefficient by up to 39.18 % and the wear rate by up to 69.79 %, while ensuring long-term friction stability.