Monodisperse Ag, Au Nanoparticles via Solvated Metal Atom Dispersion and Digestive Ripening in Ionic Liquid.

Digestive ripening (DR) is a postsynthetic protocol for the transformation of a colloid consisting of polydisperse metal nanoparticles (NPs) into a colloid composed of nearly monodisperse metal nanoparticles. This process is brought about by the digestive ripening agent, typically an organic ligand with a long alkyl chain at one end and a functional group at the other, at the boiling point of the solvent in which it is carried out, requiring long periods of time. In this work, digestive ripening of polydisperse Ag and Au nanoparticles brought about by ionic liquids (ILs) under very mild conditions (∼273 K, ∼30 min) to obtain nearly monodisperse nanoparticles has been demonstrated. Herein, the ionic liquid plays a dual role, as a digestive ripening and a stabilizing agent for the nanoparticles. Ionic liquid-assisted digestive ripening under such mild temperatures and short period of time has hitherto not been reported.