Probing the surface of silver nanocubes during their polyol synthesis, processing, and seed-mediated growth
Silver nanocubes have emerged as a model system for understanding how surface chemistry governs shape-controlled synthesis and shape preservation, in addition to their widespread use in a range of applications. This review discusses our recent progress in directly probing the surface of Ag nanocubes, with emphasis on surface-enhanced Raman scattering studies carried out under actual experimental conditions. We first discuss how the native surface is established during polyol synthesis, where chemisorbed chloride and poly(vinylpyrrolidone) act cooperatively to define and stabilize the cubic shape. We then show that sample collection, washing, and redispersion also reorganize the surface and determine whether the Ag nanocubes can retain their shape during storage. We also examine aqueous seed-mediated growth, in which rapid ligand exchange, transient AgCl formation, interfacial electron transfer, and surface reduction collectively govern the enlargement of Ag nanocubes. Taken together, these studies provide a mechanistic framework for rational synthesis of colloidal metal nanocrystals with controlled sizes and shapes.