Examples of the Superiority of Ionic Liquids and Deep Eutectic Solvents over Aqueous Solutions in Electrodeposition Processes

The current electrolytes used for metal electrodeposition mostly use aqueous solutions that limit the range and quality of possible coatings. Also, some of these solutions may contain toxic and corrosive chemicals. Thus, the importance of ionic liquids (ILs) and deep eutectic solvents (DES) becomes clear, as they can be used as green non-aqueous electrolytes for the electrodeposition of a range of reactive metals that are impossible to deposit in aqueous solutions and for the improved electrodeposition of metals that are deposable in aqueous solutions. This paper presents some examples of electrodeposition in ILs and DESs that are considered specific processes. Aluminum, as an active metal that it is impossible to electrodeposit in aqueous solution, was electrodeposited from a chloroaluminate IL. Moreover, the electrodeposition of Al was carried out in open air using a novel approach. Chromium was electrodeposited from a DES containing the environmentally friendly form of Cr (III) instead of toxic Cr (VI). Magnesium alloys, as water-sensitive substrates, were electroplated in an air and water-stable DES. Also, this paper discloses, for the first time, the procedure of pretreatment of Mg alloys for successful electroplating.