Citrate ions and chloride ions involved in the synthesis of anisotropic silver nanostructures

Anisotropic metal nanoparticles are of considerable interest to researchers because of their unique optical, electronic and catalytic properties compared with spherical nanoparticles. This Letter describes how chloride ions and citrate ions can be added to silver (Ag) nitrate solution to synthesise anisotropic silver nanostructures especially to form the Ag nanowires (AgNWs) without high hydrothermal or solvothermal operating temperatures. The AgCl colloidal precipitates were produced in the initial stage promoting the reduction of free silver ions and helping control silver ions at low concentration for the growth of AgNWs. The synthesis of AgNWs was also temperature and hydroxide radical dependent since the citrate ions could direct the growth of AgNWs at proper temperatures (over 130°C) in the absence of chloride ions. Transmission electron microscopy and UV-vis absorption spectra have been used to investigate the obtained products. The experimental results suggested that the chloride ions played a crucial role in directing the growth of anisotropic Ag nanostructures.