Sustained electroless deposition of metallic silver from a choline chloride-based ionic liquid

This work demonstrates that a sustained galvanic coating of silver can be deposited onto copper substrates from a solution of Ag+ ions in an ionic liquid (IL) based on a choline chloride (ChCl) eutectic. The sustained growth of the silver deposit was facilitated by the porous nature of the film and is proven using acoustic impedance spectroscopy on a quartz crystal microbalance (QCM). The silver and copper surfaces were characterised using atomic force microscopy (AFM) and scanning electron microscopy (SEM/EDX). In the commercial process of dip coating silver from ions in aqueous media, deposition does not continue once surface coverage has been achieved, without the use of catalysts. The process reported here using ionic liquids produces silver deposits of several microns by dip coating without the use of catalysts or strong inorganic acids.