Robust Anion Exchange Realized in Crystalline Metal Cyanamide Nanoparticles

Abstract

Solution-mediated sequential ion exchange has emerged as a powerful yet simple technique to transform nanoparticulates into a complex architecture. However, the state-of-the-art demonstration of such fine-tailored nanostructures greatly relied on cation exchange reaction because it remains to be a great challenge to apply anion exchange without interfering the original morphology and crystallinity of the target particles. Herein, metal cyanamides with a looser cation sublattice enabled by the quasi-linear [NCN]2– anion units are discovered to be ideal parent compounds to accomplish robust anion exchange reactions. The complete conversion from metal cyanamide nanoparticles to metal chalcogenide nanoparticles (CdNCN to CdS, CdNCN to CdSe, and MnNCN to MnS) is successfully realized by low-temperature reaction in colloidal solution. The nanoparticles retain both the morphology and crystallinity throughout the entire exchange process. In-depth study reveals that the structural similarity in cation packing faci...