In Situ Liquid Cell Transmission Electron Microscopy Investigation on the Dissolution-Regrowth Mechanism Dominating the Shape Evolution of Silver Nanoplates

Uniform silver nanostructures with specific geometrical morphologies, such as triangular and hexagonal nanoplates, often exhibit unique physicochemical properties with various potential applications. Despite the current progress in the liquid-phase synthesis of such Ag nanostructures, their growth mechanisms universally remain controversial due to the lack of direct visualization evidence at the nanoscale. Herein, by tracking the evolution trajectory of triangular nanoplates (TNPs) into hexagonal nanoplates (HNPs) in real-time using in situ liquid cell transmission electron microscopy, we reveal that the selective convex etching of chloride ions results in the suborbicular nanoplates (SNPs) as the intermediate shape, rather than the previously recognized truncated TNPs. Subsequently, the atomic-scale {111} stacking faults in TNPs as the driving force induce the side regrowth of the SNPs by the monomer attachment of Ag-0 atoms and the coalescence of preformed Ag clusters that were followed by atomic surface diffusion. Ag monomers preferentially redeposit to the {220} edges that grow rapidly out of existence, resulting in the formation of Ag HNPs with six {422} edges. The dissolution-regrowth evolution process found here sheds new light on the growth mechanisms of anisotropic Ag nanostructures with specific shapes. Our work not only demonstrates a potential route to the synthesis of Ag HNPs with controllable shapes and dimensions but also reveals the detailed nanoscale dissolution-regrowth mechanism during their formation, providing new insight for future rational design of controllable nanocrystal shapes.Y