Scientists in Italy have made ionic liquids more useful for electrochemistry.
Ionic liquids have long been thought promising media for electrochemical reactions, such as metal plating and finishing of a wide range of products, because they are non-volatile and environmentally friendly. However, highly concentrated solutions containing transition metal ions are required. Previously this has not been possible due to the energy cost of disrupting the ionic liquid's highly organised structure.
Now, Cinzia Chiappe at the University of Pisa, Italy and her team have exploited a phenomenon know as the common ion effect to produce highly concentrated ionic liquid solutions. Normally, the common ion effect - where the cations in a mixture of two salt solutions share the same type of anion - has the opposite effect, reducing the concentration of the cation, but Cinzia Chiappe and her team were able to generate much higher concentrations than before for silver, nickel, aluminium, chromium, cobalt, yttrium, and copper ions, by using anions common to the ionic liquid.
Using a common organic anion allows metal ions to dissolve in ionic liquids
Chiappe was taken aback by the results, saying 'We expected our ions to be more soluble, but we were actually surprised by the quantities of salts that the liquids were able to dissolve.' She suggests that the disruption to the solution is minimised by using an organic anion that is common to the existing ionic liquid.
"We expected our ions to be more soluble, but we were actually surprised by the quantities of salts that the liquids were able to dissolve. "
- Cinzia Chiappe, University of Pisa, Italy
Andrew Abbott, an expert on electrodeposition using ionic liquids from the University of Leicester, UK, predicts that this area of research is fast becoming a hot topic. 'The ability to process metals using ionic fluids is a subject that will undoubtedly expand in the near future. The area of concentrated ionic solutions is one that is fascinating and relies undoubtedly on speciation and a lot more work needs to be done to understand this phenomenon.'
Chiappe and colleagues now plan to investigate the electrochemical behaviour of their solutions.
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