Ab initio methods based on quantum mechanics are here applied to predict both the properties of MXenes and Phosphorene, 2D materials recently applied in tribological applications, and to unveil the functioning mechanisms of ZDDP, a well-established lubricant additive.

Our results on Ti-based MXenes demonstrate increased hydrophilicity with defects, unveiling the impact of terminations kind, layer thickness, and defects on water adsorption. Chemisorption is studied in relation to the surface characteristics, providing key insights into degradative oxidation [1].

Phosphorene, the 2D form of black phosphorus, presents promising tribological properties, but they are influenced by the environment, due to the tendency of phosphorene to oxidate. We calculate the phosphorene phase diagram in the presence of oxygen and water molecules to shed light into the layer stability in ambient conditions. The tendency to fully oxidize, impacting hydrophilicity, is discussed alongside the resistance to water dissociation under tribological conditions [2].

Finally, we investigate the mechanism of function of zinc dialkyldithiophosphates (ZDDPs), which is still debated despite the well-established use of this lubricant additive. Ab initio simulations compare ZDDP fragmentation in vacuum and over an iron substrate, revealing substrate-induced molecular dissociation favorability. Surface oxidation alters the dissociation path, providing valuable insights into the early stages of phosphate-based tribofilm formation [3].

These results are part of the “Advancing Solid Interface and Lubricants by First Principles Material Design (SLIDE)” project that has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant agreement No. 865633).

References

[1] E. Marquis, et al. Nano Convergence 2023, 10.1, 1-13.

[2] F. Benini, et al. Molecules 2023, 28.8, 3570.

[3] F. Benini, et al. Applied Surface Science 2024, 642, 158419.