Templated Synthesis of Monodisperse Single-Crystalline Ag Nanocrystals with Enhanced Optical Properties

Silver nanocrystals (NCs) possess excellent localized surface plasmon resonance features, and recent studies have revealed the great impact of crystallinity on their optical properties. However, the synthesis of highly monodisperse single-crystalline Ag nanocrystals (SC-Ag NCs) still encounters challenges, which require the elimination of undesirable defective NCs. Herein, we present a templated transformation method for the preparation of SC-Ag NCs with the assistance of Cu ions. The evolution from Ag2S to Ag NCs is driven by heterogeneous nucleation of the Ag on the surface of Ag2S NCs with the strong coordination effect of the alkylphosphine. The method is highly applicable for SC-Ag NCs with tunable sizes as well as SC-AgAu-alloyed NCs with an adjustable composition. The as-obtained SC-Ag NCs exhibit superior optical properties and enable enhanced performance in molecular sensing and Raman enhancement, compared to multitwinned counterparts with a similar size. This methodology contributes to the development of SC plasmonic NCs and broadens their applications in sensing, photonics, and catalysis.