Tuning the aspect ratio of silver nanostructures: the effect of solvent mole fraction and 4-aminothiophenol concentration

Abstract

In this report, we study the role of solvent on controlling the aspect ratio of silver nanostructures during their growth. More specifically, a single-step preparation of different aspect ratio silver nanostructures (R, 1-100) is demonstrated in aqueous acetonitrile using 4-aminothiophenol (ATP) as a reducing as well as surface passivating agent, where the variation of the mole fraction of acetonitrile has a dramatic effect on the morphology. The combined effect of ATP concentration and solvent mole fraction on aspect ratio is investigated by UV-Visible Spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM), Fourier Transform Infra-red Spectroscopy (FTIR) and X-ray Diffraction analysis (XRD). At lower values of mole fraction (i.e. 0.4), high aspect ratio silver nanorods are formed, whereas a mole fraction close to 1 gives no such nanostructures. In comparison, only spherical nanoparticles are formed when the mole fraction is close to 0. High aspect ratio silver nanorods are also favored by higher ATP concentration.