Anisotropic Etching of Monolayer MoS₂ Flakes for Zigzag Edges in Chemical Vapor Deposition

The edge of two-dimensional (2D) flakes of transition metal dichalcogenide (TMD) profoundly influences their optical, electronic, catalytic, and magnetic properties due to the asymmetric atomic configurations on the edge. As a reverse process of growth, the etching of monolayer MoS₂ flakes can be modulated by tuning the sulfur stoichiometric ratio in chemical vapor deposition. Here, we report studies of the high-density formation of etched pores with defined orientations on MoS₂ flakes. Structural analysis reveals that these pores are bound by zigzag edges. Our measurements show that the saturation magnetization of etched MoS₂ flakes can be up to five times higher than that of unetched counterparts, indicating that increased zigzag edge density enhances the ferromagnetism of MoS₂ flakes. These observations provide valuable insights for tailoring the edge density of 2D TMD flakes to optimize properties for targeted applications.