文摘
Ultrathin two-dimensional (2D) nanosheets (NSs) possess extraordinary properties that are attractive for both fundamental studies and technological devices. Solution-based 鈥渂ottom-up鈥?methods are emerging as promising routes to produce free-standing NSs, but the synthesis of colloidal NSs with well-defined size and shape has remained a major challenge. In this work, we report a novel method that yields 2 nm thick colloidal Cu2鈥?i>xS NSs with well-defined shape (triangular or hexagonal) and size (100 nm to 3 渭m). The key feature of our approach is the use of a synergistic interaction between halides (Br or Cl) and copper-thiolate metal鈥搊rganic frameworks to create a template that imposes 2D constraints on the Cu-catalyzed C鈥揝 thermolysis, resulting in nucleation and growth of colloidal 2D Cu2鈥?i>xS NSs. Moreover, the NS composition can be postsynthetically tailored by exploiting topotactic cation exchange reactions. This is illustrated by converting the Cu2鈥?i>xS NSs into ZnS and CdS NSs while preserving their size and shape. The method presented here thus holds great promise as a route to solution-processable compositionally diverse ultrathin colloidal NSs with well-defined shape and size.