Preparation and characterization of Ag@C composites with hexagon silver core and controllable carbon shell for surface-enhanced Raman scattering

Here, novel and stable core-shell silver-carbon nanocomposites (Ag@CSs) were obtained using glucose as the carbon source and stabilizer, silver nitrate as the silver source, and trioctylamine (TOA) as the soft template and extractant. It is worth mentioning that the shape of the silver core shows the hexagon shape, and we consider that TOA and glucose selectively adsorb the Ag (111) crystal face resulting in this growth pattern of the silver core. Owing to the enhanced local field effect around their sharp corners and edges, such structure exhibits superior properties for the surface-enhanced Raman scattering (SERS) enhancement. The hydrothermal carbon shell not only effectively avoids the agglomeration of Ag nanoparticles core, but also serves as a protective layer of the SERS active nanostructure during the whole course of the experiment. In addition, the thickness of the loose shell was significantly reduced after the product was stored in ethanol solution for a period of time. It is found that dropped cast probe molecules onto Ag@CSs have a lower SERS activity, while that immersed in the probe molecular solution for a period of time have a higher SERS activity, indicating that the detection of the probe molecules using this Ag@CSs substrate may require an interactive process. The results show that the as-obtained Ag@CSs hold tremendous potential for SERS applications for its long-term stability and superior SERS performance.