Multi-layer Ti3C2Tx-nanoparticles (MXenes) as solid lubricants – Role of surface terminations and intercalated water

MXenes, a new class of 2-dimensional materials, and in particular Ti3C2Tx-nanoparticles, have attracted considerable attention in energy storage and catalysis lately. Despite having a weakly-bounded multi-layered structure with self-lubricating ability, the usage of MXenes for tribological purposes is surprisingly underexplored. Here, we address for the first time the influence of surface terminations and intercalated water in Ti3C2Tx-nanoparticles on friction and wear when used as a solid lubricant. Ball-on-disk experiments at 4% relative humidity reveal excellent tribological properties of these Ti3C2Tx-nanoparticles with a remarkable friction reduction of about 300% coupled with the potential to greatly reduce adhesive, abrasive and tribo-chemical wear. Advanced, complementary materials' characterisation underlines the significant influence of surface terminations and intercalated water, defining them as key parameters to tailor the resulting frictional performance. Consequently, our results highlight Ti3C2Tx-nanoparticles as outstanding, next-generation solid lubricants in nano- and micro-scale systems.