Controlled synthesis of β-AgI nanoplatelets from selective nucleation of twinned Ag seeds in a tandem reaction

Abstract

Recent research has established the influence of seed nature in determining the final shapes of metallic (Ag, Au) nanocrystals. In this work, we utilize and extend this knowledge to produce anisotropic β-AgI nanoplatelets in high yield: Ag seeds (∼20 nm) with twin defects were first selectively nucleated and then reacted with I- in a one-pot tandem reaction. I- performs multiple roles of oxidative dissolution regulator and reactant and surface stabilizing agent, thereby reducing the complexity of the synthesis. Examination of the nanocrystals at different stages of the reaction via electron microscopy confirmed that the Agi nanoplates grew from twinned Ag seeds and the initial Ag seed formation step was found to be vital to the appearance of the anisotropic platelike AgI nanocrystals. In general, the reaction of preformed metallic seeds with other reactive species may provide a convenient channel for the shape-controlled production of semiconductor nanostructures, with the final shapes being determined by the structure (twinning) of the seed. Aging of the reaction mixture in the presence of light resulted in the dissolution of AgI nanoplates to form Ag dendritic nanostructures. We explained its growth based on a diffusion-limited aggregation model. © 2007 American Chemical Society.