Atomic Scale Simulation on the Anti-Pressure and Friction Reduction Mechanisms of MoS2 Monolayer

Abstract

MoS2 nanosheets can be used as solid lubricants or additives of lubricating oils to reduce friction and resist wear. However, the atomic scale mechanism still needs to be illustrated. Herein, molecular simulations on the indentation and scratching process of MoS2 monolayer supported by Pt(111) surface were conducted to study the anti-pressure and friction reduction mechanisms of the MoS2 monolayer. Three deformation stages of Pt-supported MoS2 monolayer were found during the indentation process: elastic deformation, plastic deformation and finally, complete rupture. The MoS2 monolayer showed an excellent friction reduction effect at the first two stages, as a result of enhanced load bearing capacity and reduced deformation degree of the substrate. Unlike graphene, rupture of the Pt-supported MoS2 monolayer was related primarily to out-of-plane compression of the monolayer. These results provide a new insight into the relationship between the mechanical properties and lubrication properties of 2D materials.

Effect of Compressive Prestrain on the Anti-Pressure and Anti-Wear Performance of Monolayer MoS2: A Molecular Dynamics Study

“…While the two force-depth curves almost overlap after MoS2 is completely ruptured. The result above is consistent with previous study [48], indicates that monolayer MoS2 improves the load bearing capacity of the Pt substrate. Three stages could be divided for the force-depth relation curve in Figure 3a: elastic stage (the smooth part of force-depth curves, with indentation depth < 3.0 Å for the MoS2/Pt substrate, indentation depth < 2.1 Å for the bare Pt substrate), plastic stage and the complete rupture stage of monolayer MoS2.…”

“…While the two force-depth curves almost overlap after MoS 2 is completely ruptured. The result above is consistent with previous study [48], indicates that monolayer MoS 2 improves the load bearing capacity of the Pt substrate.…”

“…In order to visually compare the friction reduction effect of monolayer MoS2 under various indentation depths, the average friction values have been calculated, as shown in Figure 6g. With increasing indentation depth, the average friction increases correspondingly, which is consistent with a previous study [48]. The results above indicate that the friction reduction effect of monolayer MoS2 depends on the deformation degree of monolayer MoS2.…”

“…While the D(S-S) is out of regularity as the indentation depth increases further. The above phenomenon indicates that the variation of the D(Mo-S) and D(S-S) are related closely to the location of the indentation depth, while the D(Mo-Mo) increases continuously with indentation depth during the indentation process.Therefore, the effect of out-of-plane compression deformation on the rupture of MoS2 is greater than the in-plane tensile deformation[48].…”

Atomic Scale Simulation on the Fracture Mechanism of Black Phosphorus Monolayer under Indentation

“…Compared with bare Pt substrate, load for BP-covered Pt substrate is smaller before rupture as shown in Figure 3 a, which indicates BP coating on Pt surface will not enhance the load bearing capacity of the substrate like graphene and MoS 2 monolayer [ 16 , 48 ]. The maximum load BP/Pt substrate can bear at elastic stage is 52.82 nN, which far exceeds 5.45 nN for the freestanding BP monolayer, hence the stress state in these two cases can be very different.…”