Role of Chemical Potential in Flake Shape and Edge Properties of Monolayer MoS2

The precise control of the edge geometry and crystal shape of monolayer MoS 2 is of particular importance for their application in nanoelectronics and photoelectro catalysts. Here, we reveal a crucial role of chemical potential in the determination of equilibrium shape (ES) and edge structure of monolayer MoS 2 by using density-functional theory calculations. Applying the Wulff construction rule, our results demonstrate the shape evolution of monolayer MoS 2 flake from the dodecagonal shape, then to the hexagonal shape, to the triangular shape with the variation of chemical potential from the Mo-rich to the S-rich condition, and the edge structure of ES changes correspondingly from mixed zigzag/armchair edges to purely zigzag edges. This finding can be applied to explain extensive experimental observations about the morphology of MoS 2 domains. Likewise, the edge magnetism and electronic structures of monolayer MoS 2 domains are found to be dependent on their edge structure, which provides specific guidance for the magnetic modulation of monolayer MoS 2 and the design of more effective MoS 2 -based catalysts.