Electronic mechanism behind the influence of intercalated heteroatom Sn on the slip energy barrier in layered WS2.

Frictional losses often result in substantial economic costs, and the application of lubricants can markedly mitigate these losses. Recently, layered materials have garnered extensive research interest due to their exceptional lubricating properties. However, the exploration of sliding mechanisms associated with intercalated heteroatoms in layered materials remains a subject of considerable uncertainty. In this work, we employ density functional theory to unravel the friction modulation mechanism of Sn atoms intercalated in layered WS₂. Our findings demonstrate that Sn intercalation significantly reduces the sliding energy barrier (down to 0.96 meV atom^-1), while the friction force and shear strength are minimized to 0.0011 nN atom^-1and 0.0008 GPa, respectively, outperforming conventional two-dimensional materials such as MoS₂and graphene. Furthermore, Sn intercalation enhances interlayer electrostatic repulsion and suppresses dynamic charge density fluctuations. To quantitatively elucidate the energy barrier variation, we propose a novel metric-total charge density difference evolution (Δρ₂). This discovery provides theoretical guidance for designing ultra-low-friction lubricants and is expected to advance energy efficiency in industrial machinery.