Unraveling the Interfacial Properties of Twisted Single-Crystal Au(111)/MoS2 Heterostructures: A Pathway to Robust Superlubricity

A comprehensive study of monolayer MoS2 on a single-crystal Au(111) surface is reported, combining ultra-high vacuum scanning probe microscopy with advanced computational methods. Kelvin probe force microscopy precisely quantified the work function of the heterointerface, while topographic analysis by contact and non-contact atomic force microscopy revealed a moire superlattice with an interfacial twist angle of 0.45 degrees between MoS2 and Au(111). To accurately model and predict the twist angle and out-of-plane corrugation of these moire superlattices, a semi-anisotropic interlayer force field based on density functional theory is developed. This avoids the limitations of conventional pairwise potentials, and our results show excellent agreement with experiments. Furthermore, friction simulations revealed a non-monotonic dependence on the interfacial twist angle, with small angles exhibiting unexpectedly large shear stress, suggesting that MoS2 could serve as an effective superlubric coating for gold. This work establishes a robust framework for the investigation of van der Waals heterostructures, bridging nanoscale experimental observations with first-principles calculations, and providing insights for the design of novel nanoscale devices with tailored electronic, mechanical, and tribological properties.