Silver Nanoplates with Special Shapes:  Controlled Synthesis and Their Surface Plasmon Resonance and Surface-Enhanced Raman Scattering Properties

Shape-controlled synthesis of metal nanostructures has opened many new possibilities to design ideal building blocks for future nanodevices. In this work, new types of monodisperse silver nanoplates with complex shapes, namely, a disklike shape and flowerlike shapes, were controllably synthesized in high yield by reducing Ag(NH3)2+ with ascorbic acid in the presence of silver seed at room temperature. Unlike previous methods for synthesizing the silver nanoplates in the presence of cetyltrimethylammonium bromide (CTAB) micelles, the use of the precursor Ag(NH3)2+, other than Ag+, provides a flexible strategy to control the procession of the reduction reaction in a mild way. These silver nanoplates with shapes of disk and flower were shown to possess surface plasmon resonance (SPR) that directly relates to their geometric shapes. As a result of their high anisotropy in shape, the flowerlike silver nanoplates exhibit excellent surface-enhanced Raman scattering (SERS) enhancement ability relative to spherical silver nanoparticles and the disklike silver nanoplates. We believe that with the efficient synthesis and excellent SERS enhancement ability, these novel flowerlike silver nanoplates may find potential applications for biological sensing and labeling systems.