The innovation engine for new materials

Yuning Shen

Yuning Shen


Fudan University




Alexandra V. Bayles

Faculty Sponsor(s): 

Matthew E. Helgeson

Faculty Sponsor's Department: 

Chemical Engineering

Project Title: 

Noble Metal Thin Film Stripping by Contact with Ionic Liquids

Project Description: 

Academics and industrialists have widely studied ionic liquids (ILs, salts with melting points below 100 °C) because their unique physical and chemical properties make them potentially useful in advanced electrochemical devices and processes, such as batteries, dye-sensitized solar cells, and green catalysis processes. It is crucial to understand the interaction of ionic liquids with metal surfaces in order to improve device performance and process efficiency. We have found that thin films of noble metals, such as gold and silver, prepared via electron-beam deposition can be stripped off and dispersed into ILs by contacting film surfaces with specific methylimidazolium-based ILs. In this work, we are investigating the process of contacting different ionic liquids with different metal films using dark-field and bright-field microscopy, as well as characterizing the metal dispersion by dynamic light scattering. We have found that the rate of stripping depends on the metal film composition and the anion in the IL. Ionic liquids with chloride or bromide anions can strip silver films while iodide based ILs can strip both gold and silver thin films at a higher stripping rate. We further tested the importance of anions by contacting metal films with aqueous solutions of ionic liquids and salts with halide anions. Both salt and ionic liquid solutions containing I- strip metal films faster than other solutions. Future work will focus on understanding the function of I- in the stripping process, revealing the mechanism of stripping and potentially synthesizing stable metal nanoparticle dispersions using this film contact method.