Nanomaterials with unique edge sites have received increasing attention due to their superior performance in various applications. Herein, we employed an effective ethylenediaminetetraacetic acid (EDTA)-assisted method to synthesize a series of exotic Bi₂Se₃ nanostructures with distinct edge sites. It was found that the products changed from smooth nanoplates to half-plate-containing and crown-like nanoplates upon increasing the molar ratio of EDTA to Bi³⁺. Mechanistic studies indicated that, when a dislocation source and relatively high supersaturation exist, the step edges in the initially formed seeds can serve as supporting sites for the growth of epilayers, leading to the formation of half-plate-containing nanoplates. In contrast, when the dislocation source and a suitably low supersaturation are simultaneously present in the system, the dislocation-driven growth mode dominates the process, in which the step edges form at the later stage of the growth responsible for the formation of crown-like nanoplates.

Shape control has proven to be a powerful and versatile means of tailoring the properties of Bi₂Se₃ nanostructures for a wide variety of applications. Here, three different Bi₂Se₃ nanostructures, i.e., spiral-type nanoplates, smooth nanoplates, and dendritic nanostructures, were prepared by manipulating the supersaturation level in the synthetic system. This mechanism study indicated that, at low supersaturation, defects in the crystal growth could cause a step edge upon which Bi₂Se₃ particles were added continuously, leading to the formation of spiral-type nanoplates. At intermediate supersaturation, the aggregation of amorphous Bi₂Se₃ particles and subsequent recrystallization resulted in the formation of smooth nanoplates. Furthermore, at high supersaturation, polycrystalline Bi₂Se₃ cores formed initially, on which anisotropic growth of Bi₂Se₃ occurred. This work not only advances our understanding of the growth mechanism but also offers a new approach to control the morphology of Bi₂Se₃ nanostructures.