Stacked CdTe/CdS Nanodiscs via Intraparticle Migration of CdTe on CdS

Heteronanostructures with anisotropic morphologies have received considerable attention due to their interesting physicochemical properties as well as potential applications in diverse technical areas such as photocatalysis, electrochemical catalysis, photovoltaic devices, and plasmonics. Typically, the heteroepitaxial growth on the preformed nanocrystal would take place on its most unstable facets to lower the overall energy of a nanoparticle. In the case of plate-like nanocrystal morphology, the widest facet is usually most stable, and thus, the heteroepitaxial growth on the widest facet is extremely difficult to induce. Due to this reason, among various heterostructures, the synthesis of stacked heteronanostructures has been particularly challenging. Herein, we demonstrate that the heterostructure of a CdS nanodisc (ND)-{CdTe nanoparticle (NP)}n, formed by partial dissolution of CdS by TOP and reformation of CdTe at the surface on the CdS ND with TOP-Te, slowly evolves into a stacked two-dimensional (2D) ND of CdS/CdTe. This work proves that the heterostructures of 2D stacked NDs do not require the direct heteroepitaxial growth or regiospecific ion exchange on the 2D nanotemplate and can be conveniently produced by a surface energy minimization process for the heteronanostructure, thus pointing to the wide avenue to further structural transformation of existing heteronanostructures into intuitively unlikely ones.