Controlled Growth of Ag/Au Bimetallic Nanorods through Kinetics Control

One-dimension noble nanomaterials have promising applications in many fields, and their growth pattern control is significant to property modulation. Herein, we report a facile strategy with which the growth pattern of Ag on the Au nanorod (NR) or decahedral nanoparticle (NP) surface can be precisely controlled and various structured Ag/Au NRs can be synthesized. Achievement of growth pattern control is mainly attributed to the adjustable reaction kinetics of Ag- to Ag-0. Slow and moderate reaction rate favor asymmetrical growth, producing Au-tipped Ag NRs and asymmetrical Ag-Au-Ag NRs, respectively. In the case of a fast reaction rate, symmetrical growth dominates and symmetrical Ag-Au-Ag NRs form. Furthermore, the prepared bimetallic NRs can be used as starting materials to generate other novel nanostructures (nanocups, nanonails, and longer Au-tipped Ag Nits). The result presented here is vital to both exploration of growth theory and constructing nanostructures of not only the Au/Ag bimetallic system but also possibly other noble bimetallic systems. Moreover, these prepared nanostructures could provide model materials for studying the physical properties (such as structure-dependent surface plasmon) or have potential applications in the medical field. For example, hollow nanocups can serve as containers for controlled release of drug, etc.