Hybridization Directionality Governs the Interaction Strength between MoS2 and Metals.

Gold-assisted exfoliation has emerged as an effective method for producing large-area monolayers of two-dimensional materials, yet its underlying mechanism remains poorly understood. While other metals also hold promise for facilitating large-area exfoliation, their practical application is hindered by oxidation in air. To address this, we fabricate heterostructures of monolayer MoS2 with polycrystalline gold, silver, copper, palladium, cobalt, and nickel via direct mechanical exfoliation of bulk molybdenite under controlled atmospheric conditions. Our photoemission spectroscopy, vibrational spectroscopy, and density functional theory results reveal the metal-dependent modification of monolayer MoS2. We identify the hybridization directionality and, in particular, the asymmetry between the bottom and top sulfur atoms as previously overlooked key factors in weakening the MoS2-MoS2 van der Waals interaction, ultimately enabling selective monolayer exfoliation.