A Simple Route for the Synthesis of Morphology-Controlled and SERS-Active Ag Dendrites with Near-Infrared Absorption

Herein we developed a simple and low-cost route for morphology-controllable synthesis of Ag dendrites based on a facile wet chemical route. The morphology of Ag dendrites was tunable by changing the concentration of capping reagent PVP. It was demonstrated that for higher concentrations of PVP, smaller Ag dendrites with shorter and smoother branches were obtained, while the ratio of the length of the branches to the body diameter of the Ag dendrites (LID) became lower. It was also shown that the concentration of added AgNO3 was very important for the formation of Ag dendrites. The presented method is amenable for extension to large-scale synthesis of Ag dendrites. The prepared Ag dendrites exhibited strong near-infrared absorption proved by UV-visible spectra. Using p-ATP as a probe molecule, the SERS activity of prepared Ag dendrites was estimated. Based on the apparent enhancement factor and the measured diameter and L/D of the morphology-controlled Ag dendrites, the relation between the morphology and the SERS activity of Ag dendrites was investigated. It was shown that the smaller Ag dendrites with a lower L/D exhibited larger SERS activity.