Electrodeposition of Cu–Zn thin films from room temperature ionic liquid

The electrosynthesis of Cu, Zn and Cu–Zn deposits from the 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid has been investigated. Anion of this metallic salt (bis(trifluoromethylsulfonyl)imide) is the same as that used as the solvent. The redox potential sequence of copper and zinc in the used ionic liquid was the same as that of aqueous solvent. The obtained voltammograms for single metal deposition exhibits several electrodeposition steps. In the case of copper, the first step does not lead to metal deposition and is attributed to the Cu(II)→Cu(I) transformation. Rest of the steps result in the Cu(0). Contrary, all the steps in zinc deposition, correspond to growth of metallic deposits. In the case of the copper–zinc alloys, their chemical composition exhibits a surprising evolution versus potential and seems to be greatly dependent on the cathodic steps. The morphology and analysis of copper, zinc and their alloys are reported.