Crystallinity Variation in Seeded Growth of Gold Nanocrystals: the Role of Additive Ag+

摘要

abstract_textpA synthetic case is reported that demonstrates the cationic additive, Ag+, can influence the crystallinity and thus shape of final product during seeded growth of Au nanocrystals. Using single-crystal Au seeds as reference, the crystallinity difference between seed and final product could be directly compared. In particular, three different types of crystallinity/morphology can be obtained by varying the concentration of Ag+ in the particle growth solutions: single-crystal quasi-spheres, multiply twinned particles (MTPs), and protruded MTPs, with no Ag+ added and solution Ag+ /Au3+ ratios of 1 : 20 and 1 : 5, respectively. The reaction kinetics are investigated using extinction spectroscopy, indicating the presence of Ag+ leads to a dampened growth of Au nanocrystals. This principle is validated using single-crystal Au seeds with different morphology and amounts. We also test the anti-corrosion performance of as-prepared Au nanocrystals with different crystallinity by treating them with sodium thiosulfate. Interestingly, in addition to reduction in size, the morphology of single-crystal ones varies from quasi-sphere to cube, indicating the anisotropy in oxidative etching of Au nanocrystals./p/abstract_text