Electrochemical (co)reduction of Ce(III) and Fe(II) ions in a dicyanamide ionic liquid

Ionic liquids (ILs) are believed to be promising media for electrochemical generation of lanthanide-based coatings under ambient conditions. Here, we explore the electrochemical behaviour of Ce(III) and Fe(II) ions in a fluorine-free [BMP][DCA] IL (1-butyl-1-methyl-pyrrolidinium dicyanamide) and describe the peculiarities of electrochemical (co)deposition of Ce and Fe on a Pt substrate. Voltammetric and microscopic data indicate that both Ce(III) and Fe(II) can be electrochemically reduced with the formation of deposits in the IL solution containing respective metal salts. We show that the Ce(III) ion electroreduction can be accelerated in the presence of Fe(II) ions in the IL solution. The acceleration effect consists in a positive shift of the cathodic wave attributed to Ce electroreduction, when it is codeposited with Fe as compared to the case, when Ce deposition occurs in the solution containing only Ce(III) ions. However, such an acceleration effect depends on the Ce(III) and Fe(II) concentrations. X-ray analysis indicates that Ce in the Ce and Ce-Fe deposits exists mostly in oxide forms which can be due to oxidation of deposited Ce by residual water. The results provide new information on the Ce-Fe codeposition that can be useful for preparation of functional coatings for application in catalysis and corrosion protection.